Search

IntroductionThough consistent evidence suggests that physical activity may delay dementia onset, the duration and amount of activity required remains unclear.MethodsWe harmonized longitudinal data of 11,988 participants from 10 cohorts in eight countries to examine the dose-response relationship between late-life physical activity and incident dementia among older adults.ResultsUsing no physical activity as a reference, dementia risk decreased with duration of physical activity up to 3.1 to 6.0hours/week (hazard ratio [HR] 0.88, 95% confidence interval [CI] 0.67 to 1.15 for 0.1 to 3.0hours/week; HR 0.68, 95% CI 0.52 to 0.89 for 3.1 to 6.0hours/week), but plateaued with higher duration. For the amount of physical activity, a similar pattern of dose-response curve was observed, with an inflection point of 9.1 to 18.0 metabolic equivalent value (MET)-hours/week (HR 0.92, 95% CI 0.70 to 1.22 for 0.1 to 9.0 MET-hours/week; HR 0.70, 95% CI 0.53 to 0.93 for 9.1 to 18.0 MET-hours/week).DiscussionThis cross-national analysis suggests that performing 3.1 to 6.0hours of physical activity and expending 9.1 to 18.0/MET-hours of energy per week may reduce dementia risk.

Afrixalus lacustris Greenbaum, Dehling, Kusamba & Portik sp. nov. Great Lakes Spiny Reed Frog urn:lsid:zoobank.org:act: 41D3C41A-4501-4BEC-BFB6-B9C6C1518DC3 Afrixalus laevis (nec Megalixalus laevis Ahl 1930)— Laurent 1950: 24; Laurent 1972: 59 (partim); Laurent 1982: 33 (partim); Schiøtz 1999: 56 (partim); Channing & Howell 2006: 137 (partim); Spawls et al. 2006: 183 (partim); Channing & Rödel 2019: 158 (partim). Holotype. UTEP 20805 (field no. ELI 605), adult male, from the vicinity of Kalundu (03.15552° S, 28.42108° E, 1482 m), South Kivu Province, DRC, collected on 21 December 2010 by Chifundera Kusamba and Félix I. Alonda (Figs. 8D–F, 12A–B). Paratopotype. UTEP 20806 (field no. ELI 606), adult male, collected with the holotype. Referred specimens. Specimens with an asterisk were not included in morphological analyses due to poor quality of preservation, lack of a voucher, or unavailability of specimen(s): UTEP 20807–08 (field nos. ELI 644, 649), vicinity of Kalundu (03.15552° S, 28.42108° E, 1482 m), South Kivu Province, DRC; UTEP 20809, 22422 (field nos. ELI 669–70), Baraka, near shore of Lake Tanganyika (04.10832° S, 29.09705° E, 777 m), South Kivu Province, DRC; UTEP 20810–11 (field nos. EBG 1316, 1319), vicinity of Irangi (01.8873° S, 28.4495° E, 820 m), South Kivu Province, DRC; UTEP 22423 (field no. MUSE 10192), Kahuzi-Biega National Park, Nanwa (02.362138° S, 28.192589° E, 1566 m), South Kivu Province, DRC; UTEP 22424 (field no. MUSE 10137), Itombwe Plateau, Mbandakila (03.47937° S, 28.413049° E, 1135 m), South Kivu Province, DRC; RMCA 77-020 -B-133–136* (four specimens), Itombwe Plateau, Tubutubu (2300 m), South Kivu Province, DRC; RMCA 77-020 -B-89–92 (field nos. MF 14–15 [two specimens]), Kitutu (ca. 03.28° S, 28.11° E, 700 m), South Kivu Province, DRC; RMCA 77-020 - B-0069–71 (1 specimen), Itula (ca. 03.27° S, 28.12° E, 650 m), South Kivu Province, DRC; RMCA 77-020 -B-0081–83, 77-20-B-0086, Kamituga (ca. 03.54° S, 27.69° E, 1050 m), South Kivu Province, DRC; RMCA 77-020 - B-0072–73 (1 specimen), Mwana (ca. 03.15° S, 28.47° E, 1650 m), South Kivu Province, DRC; UTEP 22417 (field no. CRSN 2773), Toyokana (02.02734° N, 030.06653° E, 1294 m), Ituri Province, DRC; (field no. EPLU 395 *, photo and tissue only), ca. 0.5 km E of Epulu, near Mt. Mbiya (01.39594° N, 28.58093° E, 755 m), Ituri Province, DRC; UTEP 22416 (field no. DFH 247), Bwindi Impenetrable National Park, Buhoma (00.99045° S, 29.61884° E, 1523 m), Western Region, Uganda; (field nos. DFH 1102–03 * photos and tissues only), Kibale Forest National Park, Ngogo Research Center (00.49795° N, 30.42262° E, 1363 m), Western Region, Uganda; CAS 202032–36, Bwindi Impenetrable National Park, Buhoma rd., 2 km S (by rd.) of Bizenga River (01.00975° S, 29.620694° E), Western Region, Uganda; CAS 202133, Bwindi Impenetrable National Park, small tributary to Ishasha River (00.905° S, 29.704972° E, 1280 m), Western Region, Uganda; CAS 202109, Bwindi Impenetrable National Park, Bizenga River at Buhoma rd. (00.99275° S, 29.615722° E), Western Region, Uganda; CAS 256035 *, Bwindi Impenetrable National Park, rd. north of Ruhija, Western Region, Uganda; CAS 256128–31 *, Mabira Forest Reserve, marshy area adjacent to unpolluted stream (0.4508° N, 32.9493° E, 1121 m), Mukono District, Central Region, Uganda. Diagnosis. The species is referred to the genus Afrixalus for exhibiting the following characteristics: fingers and toes webbed; tips of fingers and toes enlarged to discs; eye large; pupil vertically elliptical; tympanum indistinct; vomer ridges and teeth absent; dorsal surfaces finely shagreened with minute pointed tubercles; outer metatarsal tubercle distinct; gular gland in males. It is readily distinguished from most other members of the genus by its small size (SVL in males 18.9–22.2 mm, in females 20.8–25.7 mm), being smaller than A. dorsalis (males 25–28 mm, females 26–30 mm), A. fornasini (males 30–38 mm, females 35–40 mm), A. fulvovittatus (males 23–27 mm, females 25–28 mm), A. lacteus (males 22–27 mm, females 25–29 mm), A. leucostictus (males 27–32 mm, females 25–36 mm), A. manengubensis (males to 32 mm), A. nigeriensis (males 28–34 mm, females 32–35 mm), A. osorioi (males 27–31, females 32–35 mm), A. paradorsalis (males 28–34 mm, females 32–35 mm), A. septentrionalis (males 19–21 mm), A. vittiger (males 22–25 mm, females 25–28 mm), and A. wittei (males 27–30 mm, females 29–33 mm); and larger size than A. delicatus (males 15–19 mm, females 17–22 mm) and A. stuhlmanni (males 15–21 mm, females 17–25 mm). Its differs in dorsal coloration and pattern from all species with longitudinal stripes or bands on a yellowish-brown background (A. brachycnemis, A. crotalus, A. delicatus, A. dorsalis, A. enseticola, A. fornasini, A. fulvovittatus, A. knysnae, A. morerei, A. orophilus, A. quadrivittatus, A. schneideri, A. spinifrons, A. stuhlmanni, A. upembae, A. septentrionalis, A. vittiger, and A. wittei); species showing a conspicuous large dark dorsal blotch on a uniform background on anterior dorsum in combination with large blotches on both sides of the hip (A. leucostictus, A. manengubensis, A. osorioi, A. paradorsalis, and A. schneideri) or with longitudinal lateral dark bands (A. equatorialis and A. nigeriensis); species with a uniformly colored dorsum without conspicuous pattern except a dark dorsolateral stripe (A. aureus, A. clarkei, A. delicatus, A. fornasini, A. lacteus, A. leucostictus [dorsum with small white tubercles], A. uluguruensis, and A. weidholzi [might have a black vertebral line and dark brown flanks]); and from all remaining species having either dark stripes running from tip of snout to back, crossing each other and continuing as dorsolateral stripes (A. vibekensis, also males without asperities); anterior part of dorsum yellowish with brown pattern, posterior part of dorsum translucent (A. laevis, also males without asperities); posterior part of dorsum and dorsal sides of limbs semi-translucent with dense small dark white-edged speckles (A. dorsimaculatus); and dark blotches and transverse marks with white speckles (A. sylvaticus). It is most similar to A. phantasma sp. nov. but differs from this species in being smaller (Table 1) and showing an overall darker coloration and more contrasting dorsal pattern that is obvious even in preserved specimens (Figs. 7–8, 12). It is readily distinguished from A. phantasma sp. nov. by the more extensive hand and toe webbing (Fig. 8E–F). Description of holotype. Measurements of the holotype are provided in Table 2. Body very slender, widest at temporal region, slightly tapering to groin (Fig. 8D–F); head small (HL/SVL 0.31, HW/SVL 0.31), about as long as wide (HW/HL 0.99); snout relatively long, rounded in dorsal view and in lateral profile, slightly wider than long; canthus rostralis hardly discernible, slightly concave between eye and nostril in dorsal view; loreal region oblique; nostrils rounded, directed anterolaterally and slightly dorsally; situated much closer to tip of snout and to eye, separated from each other by distance about equal to distance between eye and nostril (IN/EN 1.02); eye directed anterolaterally, strongly protruding, very large (ED/HL 0.39), its diameter shorter than snout (ED/SL 0.90); interorbital distance much wider than upper eyelid (IO/EW 1.61) and wider than internarial distance (IO/IN 1.31); tympanum covered by skin, not visible externally; upper jaw with dentition; teeth on premaxilla larger than teeth on maxilla; choanae small, located far anterolaterally at margins of roof of mouth, its anterior edge covered by maxillary bone, therefore appearing semicircular in ventral view; vomer ridges and teeth absent; tongue heartshaped, longer than broad, bilobed for about one-fourth of its length, free distally for about two-thirds its length; densely covered with minute papillae; median lingual process absent. Dorsal surfaces of head, trunk, and limbs and lateral surfaces of trunk finely shagreened; tiny pointed, widely scattered tubercles on dorsum, more numerous posteriorly than anteriorly; supratympanic fold absent; few tubercles at rear end of mandible without pointed tips; ventral side of head smooth; vocal sac present; gular gland of vocal sac smooth, large and wide, covering about 70 percent of throat width (Fig. 8E); chest smooth, abdomen weakly areolate; ventral side of limbs smooth; short transverse fold above vent. Forelimbs slender; hand large (HaL/SVL 0.28); tips of fingers enlarged into large disks, each with circummarginal groove; relative length of fingers: I I 2-/2 II 2-/3- III 2.25/2 IV; thenar tubercle oval, small and very low, about one-fourth length of metacarpal of Finger I; inner palmar tubercle and outer palmar tubercle very low, small, rounded, almost indiscernible. Hind limbs slender, moderately long; heel reaching to level of eye when legs adpressed forwardly to body; crus moderately long (TibL/SVL 0.44), slightly shorter than thigh; heels not touching each other when knees flexed and thighs held perpendicularly to median plane; foot subequal in length to crus (FoL/TibL 0.94); relative length of toes: I I 1.5/2+ II 1+/2+ III 1+/2+ IV 2/1+ V (Fig. 8E); inner metatarsal tubercle moderately prominent, elongated, about half length of metatarsus of Toe I; outer metatarsal tubercle small, rounded. Coloration in life. During night, skin on dorsal side of head, trunk, forelimbs, crus and tarsus light brown with more or less regular, locally more densely clustered dark brown speckling; distinct dark brown transverse stripe between upper eyelids, another less distinct one in scapula region, and another narrow one at level of anterior end of pelvis; dorsal skin of thigh largely unpigmented with only a broad stripe of widely scattered brown pigmentation; distinct dark brown band along canthus, continuing behind eye on both sides of trunk to level of pelvis; tubercles below eye and in tympanic region at rear end of jaw white; dark brown stripe running diagonally on middle of tibia, forming interrupted, inverted U-shaped band together with pelvic spots when legs folded against body; skin of ventral side of head, trunk and limbs largely unpigmented and translucent; gular gland bright yellow; fingers and toes yellow (Fig. 12). During day, basic dorsal coloration light brown; dark brown dorsal speckles, spots and stripes in more pronounced contrast to basic coloration, more distinctly visible. Coloration in preservative. Dorsal basic coloration largely faded to light brown; darker dorsal pattern elements dark brown, clearly visible; color of gular gland, fingers and toes faded to white (Fig. 8D–F). Variation. The paratypes match the holotype in general appearance and proportions. Coloration and color pattern varies from light-cream to yellowish-orange with a few relatively large and darker blotches and vermiculation, light speckling and indistinct dorsolateral stripe to an almost reticulated pattern of contrasting bright and dark elements with a broad and conspicuous brown dorsolateral band (Fig. 12). Pedal webbing variation is I 1.5[100]/2+[100] II 1+[100]/2+[100] III 1 +[50],1.25[50]/2+[100] IV 2 [100]/1+[100] V. Bioacoustics. The advertisement call and other vocalizations are unknown. Ecology and natural history. We collected males and females in swamps in forest openings and near forest edges (Fig. 11B), from vegetation at the edge of streams (or on vegetation overhanging them) in forest, and from non-forest vegetation near the shore of Lake Tanganyika. Egg deposition has not been observed and tadpoles are unknown. An adult male (CAS 256035) was found in Bwindi Impenetrable National Park (Uganda) ca. 2 m above ground in a tree fern “either calling or moving to a calling site (similar to ‘running’ of Kassina)” (D. Blackburn, in litt., 22 July 2021). Laurent (1955) noted the species from transitional forest. In his paper on amphibians of Virunga National Park, Laurent (1972) noted the species is most commonly found in swamps with herbaceous vegetation in secondary forest, and more rarely, in primary forest. Laurent (1982) noted that, in general, the species is common in the foliage of shrubs in dense forests. He also recorded it from “une mare sombre” (i.e., a dark pond) in syntopy with Chiromantis at Kitutu (DRC), marshes where it reproduces by sticking its eggs under the leaves of fountain grass (Pennisetum, Shabunda, DRC), a shaded bank of a pond in syntopy with Hyperolius “ tuberculatus ” (likely H. hutsebauti sensu Bell et al. 2017) and H. frontalis; the center of this pond had reeds harboring H. kivuensis and Afrixalus orophilus (Shabunda, DRC). Laurent (1983:352) listed the species (along with Phrynobatrachus petropedetoides and Hyperolius frontalis) from “shadowy puddles of the thick transition forest.” Etymology. The species epithet is the Latin adjective “ lacustris,” meaning belonging to or dwelling in lakes; in allusion to the distribution of the new species in the region of the African Great Lakes. Distribution and conservation. The species is distributed from lowland rainforest of the Congo Basin at 460 m (Omaniundu, DRC, Laurent 1982) to transitional forests of the Albertine Rift at 1650 m (Mwana, DRC) and east as far as Mabira Forest, Uganda (1121 m). As shown in Figure 5, the species has a relatively large distribution, including several national parks and protected areas (e.g., Virunga National Park, Bwindi Impenetrable National Park), and thus is not likely to be threatened based on a limited distribution. Using GeoCAT, its extent of occurrence is estimated as 409,238 km ² and its area of occupancy as 160 km ² (Bachman et al. 2011). We therefore classify this species as Least Concern according to the IUCN Red List criteria (IUCN 2021). Four specimens (RMCA 77-020-B-133–136) from Tubutubu, Itombwe Plateau (2300 m) are problematic because they are morphologically consistent with A. lacustris, but they were collected from a substantially higher elevation than all other known specimens. Coordinates for Tubutubu provided by RMCA (4° S, 28.933° E) suggest the locality is east of the highest point of the plateau at an elevation of about 1400 m on Google Earth. Although it is possible that the specimens were collected at the latter elevation, Laurent (1982) mentions bamboo forest as the habitat, which usually occurs at the highest elevations of the Itombwe Plateau (Doumenge 1998). No clarity is offered by Laurent (1964), because he does not mention any Afrixalus in his study of the ecology and distribution of amphibians of the Itombwe Plateau. Given this conflicting information, we do not include the Tubutubu specimens in our current understanding of the elevational distribution of A. lacustris (see gray triangle in Fig. 5)., Published as part of Greenbaum, Eli, Portik, Daniel M., Allen, Kaitlin E., Vaughan, Eugene R., Badjedjea, Gabriel, Barej, Michael F., Behangana, Mathias, Conkey, Nancy, Dumbo, Bonny, Gonwouo, Legrand N., Hirschfeld, Mareike, Hughes, Daniel F., Igunzi, Félix, Kusamba, Chifundera, Lukwago, Wilber, Masudi, Franck M., Penner, Johannes, Reyes, Jesús M., Rödel, Mark-Oliver, Roelke, Corey E., Romero, Soraya & Dehling, J. Maximilian, 2022, Systematics of the Central African Spiny Reed Frog Afrixalus laevis (Anura Hyperoliidae), with the description of two new species from the Albertine Rift, pp. 201-232 in Zootaxa 5174 (3) on pages 218-223, DOI: 10.11646/zootaxa.5174.3.1, http://zenodo.org/record/6986207, {"references":["Ahl, E. (1930) Ueber die afrikanischen Arten der Baumfroschgattung Megalixalus. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin, 1930, 89 - 102.","Laurent, R. (1950) Genres Afrixalus et Hyperolius (Amphibia Salientia). Exploration du Parc National Albert, Mission G. F. De Witte (1933 - 1935), 64, 5 - 120, 7 pls.","Laurent, R. F. (1972) Amphibiens. Exploration du Parc National des Virunga, Deuxieme Serie, 22, 1 - 125, 11 pls.","Laurent, R. F. (1982) Le genre Afrixalus Laurent (Hyperoliidae) en Afrique Centrale. Annales du Musee Royal de l'Afrique Centrale, Serie in Octavo, Science Zoologique, 235, 1 - 93.","Schiotz, A. (1999) Treefrogs of Africa. Edition Chimaira, Frankfurt am Main, 350 pp.","Channing, A. & Howell, K. M. (2006) Amphibians of East Africa. Cornell University Press, Ithaca, New York, New York, xi + 418 pp.","Spawls, S., Howell, K. M. & Drewes, R. C. (2006) Pocket Guide to the Reptiles and Amphibians of East Africa. A & C Black Publishers, London, 240 pp.","Channing, A. & Rodel, M. - O. (2019) Field Guide to the Frogs & Other Amphibians of Africa. Struik Nature, Cape Town, 408 pp.","Laurent, R. F. (1955) Apercu de la biogeographie des batraciens et des reptiles de la region des grand lacs. Bulletin de la Societe Zoologique de France, 79, 290 - 310.","Bell, R. C., Parra, J. L., Badjedjea, G., Barej, M. F., Blackburn, D. C., Burger, M., Channing, A., Dehling, J. M., Greenbaum, E., Gvozdik, V., Kielgast, J., Kusamba, C., Lotters, S., McLaughlin, P. J., Nagy, Z. T., Rodel, M. - O., Portik, D. M., Stuart, B. L., VanDerWal, J. & Zamudio, K. R. (2017) Idiosyncratic responses to climate-driven forest fragmentation and marine incursions in reed frogs from Central Africa and the Gulf of Guinea Islands. Molecular Ecology, 26 (19), 5223 - 5244. https: // doi. org / 10.1111 / mec. 14260","Laurent, R. F. (1983) About the herpetofauna of Central African montane forest. In: Rhodin, A. G. J. & Miyata, K. (Eds.), Advances in Herpetology and Evolutionary Biology: Essays in Honor of Ernest E. Williams. Museum of Comparative Zoology, Cambridge, Massachusetts, pp. 350 - 358.","Bachman, S., Moat, J., Hill, A., de la Torre, J. & Scott, B. (2011) Supporting Red List threat assessments with GeoCAT: Geospatial Conservation Assessment Tool. ZooKeys, 150, 117 - 126. https: // doi. org / 10.3897 / zookeys. 150.2109","IUCN (2021) IUCN Red List Categories and Criteria: Version 2021 - 3. Available from: https: // www. iucnredlist. org / (accessed 25 May 2022)","Doumenge, C. (1998) Forest diversity, distribution, and dynamique in the Itombwe Mountains, South-Kivu, Congo Democratic Republic. Mountain Research and Development, 18 (3), 249 - 264. https: // doi. org / 10.2307 / 3674036","Laurent, R. F. (1964) Adaptive modifications in frogs of an isolated highland fauna in Central Africa. Evolution, 18 (3), 458 - 467. https: // doi. org / 10.1111 / j. 1558 - 5646.1964. tb 01622. x"]}

Afrixalus lacustris Greenbaum, Dehling, Kusamba & Portik sp. nov. Great Lakes Spiny Reed Frog urn:lsid:zoobank.org:act: 41D3C41A-4501-4BEC-BFB6-B9C6C1518DC3 Afrixalus laevis (nec Megalixalus laevis Ahl 1930)— Laurent 1950: 24; Laurent 1972: 59 (partim); Laurent 1982: 33 (partim); Schiøtz 1999: 56 (partim); Channing & Howell 2006: 137 (partim); Spawls et al. 2006: 183 (partim); Channing & Rödel 2019: 158 (partim). Holotype. UTEP 20805 (field no. ELI 605), adult male, from the vicinity of Kalundu (03.15552° S, 28.42108° E, 1482 m), South Kivu Province, DRC, collected on 21 December 2010 by Chifundera Kusamba and Félix I. Alonda (Figs. 8D–F, 12A–B). Paratopotype. UTEP 20806 (field no. ELI 606), adult male, collected with the holotype. Referred specimens. Specimens with an asterisk were not included in morphological analyses due to poor quality of preservation, lack of a voucher, or unavailability of specimen(s): UTEP 20807–08 (field nos. ELI 644, 649), vicinity of Kalundu (03.15552° S, 28.42108° E, 1482 m), South Kivu Province, DRC; UTEP 20809, 22422 (field nos. ELI 669–70), Baraka, near shore of Lake Tanganyika (04.10832° S, 29.09705° E, 777 m), South Kivu Province, DRC; UTEP 20810–11 (field nos. EBG 1316, 1319), vicinity of Irangi (01.8873° S, 28.4495° E, 820 m), South Kivu Province, DRC; UTEP 22423 (field no. MUSE 10192), Kahuzi-Biega National Park, Nanwa (02.362138° S, 28.192589° E, 1566 m), South Kivu Province, DRC; UTEP 22424 (field no. MUSE 10137), Itombwe Plateau, Mbandakila (03.47937° S, 28.413049° E, 1135 m), South Kivu Province, DRC; RMCA 77-020 -B-133–136* (four specimens), Itombwe Plateau, Tubutubu (2300 m), South Kivu Province, DRC; RMCA 77-020 -B-89–92 (field nos. MF 14–15 [two specimens]), Kitutu (ca. 03.28° S, 28.11° E, 700 m), South Kivu Province, DRC; RMCA 77-020 - B-0069–71 (1 specimen), Itula (ca. 03.27° S, 28.12° E, 650 m), South Kivu Province, DRC; RMCA 77-020 -B-0081–83, 77-20-B-0086, Kamituga (ca. 03.54° S, 27.69° E, 1050 m), South Kivu Province, DRC; RMCA 77-020 - B-0072–73 (1 specimen), Mwana (ca. 03.15° S, 28.47° E, 1650 m), South Kivu Province, DRC; UTEP 22417 (field no. CRSN 2773), Toyokana (02.02734° N, 030.06653° E, 1294 m), Ituri Province, DRC; (field no. EPLU 395 *, photo and tissue only), ca. 0.5 km E of Epulu, near Mt. Mbiya (01.39594° N, 28.58093° E, 755 m), Ituri Province, DRC; UTEP 22416 (field no. DFH 247), Bwindi Impenetrable National Park, Buhoma (00.99045° S, 29.61884° E, 1523 m), Western Region, Uganda; (field nos. DFH 1102–03 * photos and tissues only), Kibale Forest National Park, Ngogo Research Center (00.49795° N, 30.42262° E, 1363 m), Western Region, Uganda; CAS 202032–36, Bwindi Impenetrable National Park, Buhoma rd., 2 km S (by rd.) of Bizenga River (01.00975° S, 29.620694° E), Western Region, Uganda; CAS 202133, Bwindi Impenetrable National Park, small tributary to Ishasha River (00.905° S, 29.704972° E, 1280 m), Western Region, Uganda; CAS 202109, Bwindi Impenetrable National Park, Bizenga River at Buhoma rd. (00.99275° S, 29.615722° E), Western Region, Uganda; CAS 256035 *, Bwindi Impenetrable National Park, rd. north of Ruhija, Western Region, Uganda; CAS 256128–31 *, Mabira Forest Reserve, marshy area adjacent to unpolluted stream (0.4508° N, 32.9493° E, 1121 m), Mukono District, Central Region, Uganda. Diagnosis. The species is referred to the genus Afrixalus for exhibiting the following characteristics: fingers and toes webbed; tips of fingers and toes enlarged to discs; eye large; pupil vertically elliptical; tympanum indistinct; vomer ridges and teeth absent; dorsal surfaces finely shagreened with minute pointed tubercles; outer metatarsal tubercle distinct; gular gland in males. It is readily distinguished from most other members of the genus by its small size (SVL in males 18.9–22.2 mm, in females 20.8–25.7 mm), being smaller than A. dorsalis (males 25–28 mm, females 26–30 mm), A. fornasini (males 30–38 mm, females 35–40 mm), A. fulvovittatus (males 23–27 mm, females 25–28 mm), A. lacteus (males 22–27 mm, females 25–29 mm), A. leucostictus (males 27–32 mm, females 25–36 mm), A. manengubensis (males to 32 mm), A. nigeriensis (males 28–34 mm, females 32–35 mm), A. osorioi (males 27–31, females 32–35 mm), A. paradorsalis (males 28–34 mm, females 32–35 mm), A. septentrionalis (males 19–21 mm), A. vittiger (males 22–25 mm, females 25–28 mm), and A. wittei (males 27–30 mm, females 29–33 mm); and larger size than A. delicatus (males 15–19 mm, females 17–22 mm) and A. stuhlmanni (males 15–21 mm, females 17–25 mm). Its differs in dorsal coloration and pattern from all species with longitudinal stripes or bands on a yellowish-brown background (A. brachycnemis, A. crotalus, A. delicatus, A. dorsalis, A. enseticola, A. fornasini, A. fulvovittatus, A. knysnae, A. morerei, A. orophilus, A. quadrivittatus, A. schneideri, A. spinifrons, A. stuhlmanni, A. upembae, A. septentrionalis, A. vittiger, and A. wittei); species showing a conspicuous large dark dorsal blotch on a uniform background on anterior dorsum in combination with large blotches on both sides of the hip (A. leucostictus, A. manengubensis, A. osorioi, A. paradorsalis, and A. schneideri) or with longitudinal lateral dark bands (A. equatorialis and A. nigeriensis); species with a uniformly colored dorsum without conspicuous pattern except a dark dorsolateral stripe (A. aureus, A. clarkei, A. delicatus, A. fornasini, A. lacteus, A. leucostictus [dorsum with small white tubercles], A. uluguruensis, and A. weidholzi [might have a black vertebral line and dark brown flanks]); and from all remaining species having either dark stripes running from tip of snout to back, crossing each other and continuing as dorsolateral stripes (A. vibekensis, also males without asperities); anterior part of dorsum yellowish with brown pattern, posterior part of dorsum translucent (A. laevis, also males without asperities); posterior part of dorsum and dorsal sides of limbs semi-translucent with dense small dark white-edged speckles (A. dorsimaculatus); and dark blotches and transverse marks with white speckles (A. sylvaticus). It is most similar to A. phantasma sp. nov. but differs from this species in being smaller (Table 1) and showing an overall darker coloration and more contrasting dorsal pattern that is obvious even in preserved specimens (Figs. 7–8, 12). It is readily distinguished from A. phantasma sp. nov. by the more extensive hand and toe webbing (Fig. 8E–F). Description of holotype. Measurements of the holotype are provided in Table 2. Body very slender, widest at temporal region, slightly tapering to groin (Fig. 8D–F); head small (HL/SVL 0.31, HW/SVL 0.31), about as long as wide (HW/HL 0.99); snout relatively long, rounded in dorsal view and in lateral profile, slightly wider than long; canthus rostralis hardly discernible, slightly concave between eye and nostril in dorsal view; loreal region oblique; nostrils rounded, directed anterolaterally and slightly dorsally; situated much closer to tip of snout and to eye, separated from each other by distance about equal to distance between eye and nostril (IN/EN 1.02); eye directed anterolaterally, strongly protruding, very large (ED/HL 0.39), its diameter shorter than snout (ED/SL 0.90); interorbital distance much wider than upper eyelid (IO/EW 1.61) and wider than internarial distance (IO/IN 1.31); tympanum covered by skin, not visible externally; upper jaw with dentition; teeth on premaxilla larger than teeth on maxilla; choanae small, located far anterolaterally at margins of roof of mouth, its anterior edge covered by maxillary bone, therefore appearing semicircular in ventral view; vomer ridges and teeth absent; tongue heartshaped, longer than broad, bilobed for about one-fourth of its length, free distally for about two-thirds its length; densely covered with minute papillae; median lingual process absent. Dorsal surfaces of head, trunk, and limbs and lateral surfaces of trunk finely shagreened; tiny pointed, widely scattered tubercles on dorsum, more numerous posteriorly than anteriorly; supratympanic fold absent; few tubercles at rear end of mandible without pointed tips; ventral side of head smooth; vocal sac present; gular gland of vocal sac smooth, large and wide, covering about 70 percent of throat width (Fig. 8E); chest smooth, abdomen weakly areolate; ventral side of limbs smooth; short transverse fold above vent. Forelimbs slender; hand large (HaL/SVL 0.28); tips of fingers enlarged into large disks, each with circummarginal groove; relative length of fingers: I I 2-/2 II 2-/3- III 2.25/2 IV; thenar tubercle oval, small and very low, about one-fourth length of metacarpal of Finger I; inner palmar tubercle and outer palmar tubercle very low, small, rounded, almost indiscernible. Hind limbs slender, moderately long; heel reaching to level of eye when legs adpressed forwardly to body; crus moderately long (TibL/SVL 0.44), slightly shorter than thigh; heels not touching each other when knees flexed and thighs held perpendicularly to median plane; foot subequal in length to crus (FoL/TibL 0.94); relative length of toes: I I 1.5/2+ II 1+/2+ III 1+/2+ IV 2/1+ V (Fig. 8E); inner metatarsal tubercle moderately prominent, elongated, about half length of metatarsus of Toe I; outer metatarsal tubercle small, rounded. Coloration in life. During night, skin on dorsal side of head, trunk, forelimbs, crus and tarsus light brown with more or less regular, locally more densely clustered dark brown speckling; distinct dark brown transverse stripe between upper eyelids, another less distinct one in scapula region, and another narrow one at level of anterior end of pelvis; dorsal skin of thigh largely unpigmented with only a broad stripe of widely scattered brown pigmentation; distinct dark brown band along canthus, continuing behind eye on both sides of trunk to level of pelvis; tubercles below eye and in tympanic region at rear end of jaw white; dark brown stripe running diagonally on middle of tibia, forming interrupted, inverted U-shaped band together with pelvic spots when legs folded against body; skin of ventral side of head, trunk and limbs largely unpigmented and translucent; gular gland bright yellow; fingers and toes yellow (Fig. 12). During day, basic dorsal coloration light brown; dark brown dorsal speckles, spots and stripes in more pronounced contrast to basic coloration, more distinctly visible. Coloration in preservative. Dorsal basic coloration largely faded to light brown; darker dorsal pattern elements dark brown, clearly visible; color of gular gland, fingers and toes faded to white (Fig. 8D–F). Variation. The paratypes match the holotype in general appearance and proportions. Coloration and color pattern varies from light-cream to yellowish-orange with a few relatively large and darker blotches and vermiculation, light speckling and indistinct dorsolateral stripe to an almost reticulated pattern of contrasting bright and dark elements with a broad and conspicuous brown dorsolateral band (Fig. 12). Pedal webbing variation is I 1.5[100]/2+[100] II 1+[100]/2+[100] III 1 +[50],1.25[50]/2+[100] IV 2 [100]/1+[100] V. Bioacoustics. The advertisement call and other vocalizations are unknown. Ecology and natural history. We collected males and females in swamps in forest openings and near forest edges (Fig. 11B), from vegetation at the edge of streams (or on vegetation overhanging them) in forest, and from non-forest vegetation near the shore of Lake Tanganyika. Egg deposition has not been observed and tadpoles are unknown. An adult male (CAS 256035) was found in Bwindi Impenetrable National Park (Uganda) ca. 2 m above ground in a tree fern “either calling or moving to a calling site (similar to ‘running’ of Kassina)” (D. Blackburn, in litt., 22 July 2021). Laurent (1955) noted the species from transitional forest. In his paper on amphibians of Virunga National Park, Laurent (1972) noted the species is most commonly found in swamps with herbaceous vegetation in secondary forest, and more rarely, in primary forest. Laurent (1982) noted that, in general, the species is common in the foliage of shrubs in dense forests. He also recorded it from “une mare sombre” (i.e., a dark pond) in syntopy with Chiromantis at Kitutu (DRC), marshes where it reproduces by sticking its eggs under the leaves of fountain grass (Pennisetum, Shabunda, DRC), a shaded bank of a pond in syntopy with Hyperolius “ tuberculatus ” (likely H. hutsebauti sensu Bell et al. 2017) and H. frontalis; the center of this pond had reeds harboring H. kivuensis and Afrixalus orophilus (Shabunda, DRC). Laurent (1983:352) listed the species (along with Phrynobatrachus petropedetoides and Hyperolius frontalis) from “shadowy puddles of the thick transition forest.” Etymology. The species epithet is the Latin adjective “ lacustris,” meaning belonging to or dwelling in lakes; in allusion to the distribution of the new species in the region of the African Great Lakes. Distribution and conservation. The species is distributed from lowland rainforest of the Congo Basin at 460 m (Omaniundu, DRC, Laurent 1982) to transitional forests of the Albertine Rift at 1650 m (Mwana, DRC) and east as far as Mabira Forest, Uganda (1121 m). As shown in Figure 5, the species has a relatively large distribution, including several national parks and protected areas (e.g., Virunga National Park, Bwindi Impenetrable National Park), and thus is not likely to be threatened based on a limited distribution. Using GeoCAT, its extent of occurrence is estimated as 409,238 km ² and its area of occupancy as 160 km ² (Bachman et al. 2011). We therefore classify this species as Least Concern according to the IUCN Red List criteria (IUCN 2021). Four specimens (RMCA 77-020-B-133–136) from Tubutubu, Itombwe Plateau (2300 m) are problematic because they are morphologically consistent with A. lacustris, but they were collected from a substantially higher elevation than all other known specimens. Coordinates for Tubutubu provided by RMCA (4° S, 28.933° E) suggest the locality is east of the highest point of the plateau at an elevation of about 1400 m on Google Earth. Although it is possible that the specimens were collected at the latter elevation, Laurent (1982) mentions bamboo forest as the habitat, which usually occurs at the highest elevations of the Itombwe Plateau (Doumenge 1998). No clarity is offered by Laurent (1964), because he does not mention any Afrixalus in his study of the ecology and distribution of amphibians of the Itombwe Plateau. Given this conflicting information, we do not include the Tubutubu specimens in our current understanding of the elevational distribution of A. lacustris (see gray triangle in Fig. 5).

Afrixalus phantasma Dehling, Greenbaum, Kusamba & Portik sp. nov. Ghost Spiny Reed Frog urn:lsid:zoobank.org:act: 1B2DBF26-5B0A-4DA8-B65E-0BC01704C1B4 Afrixalus laevis (nec Megalixalus laevis Ahl 1930)— Laurent 1972: 59 (partim); Laurent 1982: 33 (partim); Schiøtz 1999: 56 (partim); Channing & Howell 2006: 137 (partim); Spawls et al. 2006: 183 (partim); Channing & Rödel 2019: 158 (partim). Holotype. ZFMK 103454 (field no. JMD 723), adult male, from Gishwati Forest (01.823745° S, 29.360373° E, 2084 m), now part of Gishwati-Mukura National Park, Western Province, Rwanda, collected on 5 April 2011 by J. Maximilian Dehling and Bonny Dumbo (Figs. 7A, 8A–C). Paratypes. ZFMK 103455 (field no. JMD 722), adult female, collected with the holotype; ZFMK 103456 (field no. JMD 2015-30), adult male, ZFMK 103457 (field no. JMD 2015-31), adult female, from the type locality in Gishwati Forest, both collected on 27 September 2015 by J. Maximilian Dehling and Bonny Dumbo; ZFMK 103458–60 (field nos. JMD 677–679), three adult males, collected on 19 March 2011 by J. Maximilian Dehling, ZFMK 103461–62 (field nos. JMD 954–955), two adult males, collected on 16 February 2013 by J. Maximilian Dehling, all from Kamiranzovu Swamp (02.477165° S, 29.158243° E, 1962 m), Nyungwe National Park, Western Province, Rwanda; UTEP 20791–20792 (field nos. EBG 2838, 2843), two adult males, collected on 21 December 2009 by Chifundera Kusamba, Wandege M. Muninga, Mwenebatu M. Aristote, and Maurice Luhumyo from Nyakasanza Swamp near Tshibati (02.22886° S, 28.78017° E, 1979 m), South Kivu Province, DRC. Referred specimens. UTEP 20802 (field no. EBG 1198), forest ca. 4 km NW of Lwiro (02.2226° S, 28.7754° E, 2077 m), South Kivu Province, DRC; UTEP 20803, 22418–20 (field nos. EBG 1232, 1238–40), Kahuzi-Biega National Park, Mugaba (02.2750° S, 28.6631° E, 2298 m), South Kivu Province, DRC; UTEP 20804 (field no. EBG 1283), Kahuzi-Biega National Park, Chinya (02.2671° S, 28.6455° E, 2267 m), South Kivu Province, DRC; UTEP 20793–94 (field nos. EBG 2844–45), Nyakasanza Swamp near Tshibati (02.22886° S, 28.78017° E, 1979 m), South Kivu Province, DRC; UTEP 20795–20800, 22421 (field nos. ELI 414–20), Nyakasanza Swamp near Tshibati (02.22829° S, 28.77972° E, 1979 m), South Kivu Province, DRC; UTEP 20801 (field no. ELI 425), Chanjoka (02.21261° S, 28.77644° E, 2115 m), South Kivu Province, DRC. Diagnosis. The species is referred to the genus Afrixalus by exhibiting the following characteristics: fingers and toes webbed; tips of fingers and toes enlarged to discs; eye large; pupil vertically elliptical; tympanum indistinct; vomer ridges and teeth absent; dorsal surfaces finely shagreened with minute pointed tubercles; outer metatarsal tubercle distinct; gular gland in males. It is readily distinguished from most other members of the genus by its small size (SVL in males 20.1–24.6 mm, in females 22.6–26.4 mm), being smaller than A. dorsalis (males 25–28 mm, females 26–30 mm), A. fornasini (males 30–38 mm, females 35–40 mm), A. lacteus (males 22–27 mm, females 25– 29 mm), A. leucostictus (males 27–32 mm, females 25–36 mm), A. manengubensis (males to 32 mm), A. nigeriensis (males 28–34 mm, females 32–35 mm), A. osorioi (males 27–31 mm, females 32–35 mm), A. paradorsalis (males 28–34 mm, females 32–35 mm), A. septentrionalis (males 19–21 mm), and A. wittei (males 27–30 mm, females 29–33 mm); and larger than A. brachycnemis (males 18–21 mm, females 20–22 mm), A. delicatus (males 15–19 mm, females 17–22 mm), A. spinifrons (males to 20 mm, females to 25 mm), and A. stuhlmanni (males 15–21 mm, females 17–25 mm). Its differs in dorsal coloration and pattern from all species with longitudinal stripes or bands on a yellowish-brown background (A. brachycnemis, A. crotalus, A. delicatus, A. dorsalis, A. enseticola, A. fornasini, A. fulvovittatus, A. knysnae, A. morerei, A. orophilus, A. quadrivittatus, A. schneideri, A. spinifrons, A. stuhlmanni, A. upembae, A. septentrionalis, A. vittiger, and A. wittei); species with a conspicuous large dark dorsal blotch on a uniform background on anterior dorsum in combination with large blotches on both sides of the hip (A. leucostictus, A. manengubensis, A. osorioi, A. paradorsalis, and A. schneideri) or with longitudinal lateral dark bands (A. equatorialis and A. nigeriensis); species with a uniformly colored dorsum without conspicuous pattern except a dark dorsolateral stripe (A. aureus, A. clarkei, A. delicatus, A. fornasini, A. lacteus, A. leucostictus [dorsum with small white tubercles], A. uluguruensis, and A. weidholzi [might have a black vertebral line and dark brown flanks]); and from all remaining species having either dark stripes running from tip of snout to back, crossing each other and continuing as dorsolateral stripes (A. vibekensis, also males without asperities); anterior part of dorsum yellowish with brown pattern, posterior part of dorsum translucent (A. laevis, also males without asperities); posterior part of dorsum and dorsal sides of limbs semi-translucent with dense small dark white-edged speckles (A. dorsimaculatus); and dark blotches and transverse marks with white speckles (A. sylvaticus). The advertisement calls of the following species of Afrixalus consist of a long series of clicks, often initiated by a long buzzing note, and thus differ from the call of A. phantasma: A. aureus, A. brachycnemis, A. clarkei, A. crotalus, A. delicatus, A. dorsalis, A. fornasini, A. fulvovittatus, A. knysnae, A. nigeriensis, A. morerei, A. osorioi, A. quadrivittatus, A. septentrionalis, A. spinifrons, A. vibekensis, A. vittiger, A. weidholzi, and A. wittei. The advertisement calls of the remaining species for which information is available differ from the call of A. phantasma in the following characteristics (in parentheses): A. dorsimaculatus (soft, short buzzing rattle, usually repeated three times), A. equatorialis (series of five notes, repeated at 15–20/s and initiated by a long buzz, energy maximum at 2000–2500 Hz), A. lacteus (8–9 notes, 14–15 pulses,>300 pulses/s), A. paradorsalis (2–3 notes, energy maximum at 2700 Hz), A. stuhlmanni (2–9 notes, energy maximum at 4200–5100 Hz), and A. sylvaticus (2–5 notes, energy maximum at 4000–4500 Hz). The new species is most similar to A. lacustris sp. nov. from which it differs by a number of characteristics (see below). Description of holotype. Measurements of the holotype are provided in Table 2. Body very slender, widest at temporal region, slightly tapering to groin (Fig. 8A–C); head small (HL/SVL 0.31, HW/SVL 0.30), about as long as wide (HW/HL 0.98); snout relatively long, rounded in dorsal view and in lateral profile, slightly longer than wide; canthus rostralis hardly distinct, straight between eye and nostril; loreal region oblique; nostrils rounded, directed anterodorsally and slightly laterally; situated much closer to tip of snout and to eye, separated from each other by distance larger than distance between eye and nostril (IN/EN 1.15); eye directed anterolaterally, strongly protruding, very large (ED/HL 0.41), its diameter shorter than snout (ED/SL 0.84); interorbital distance much wider than upper eyelid and wider than internarial distance (IO/IN 1.21); tympanum covered by skin, not visible externally; upper jaw with dentition; teeth on premaxilla larger than teeth on maxilla; choanae small, located far anterolaterally at margins of roof of mouth, its anterior edge covered by maxillary bone, therefore appearing semicircular in ventral view; vomer ridges and teeth absent; tongue short and moderately broad, bilobed for about one-sixth of its length, free distally for about half its length; densely covered with minute papillae; median lingual process absent. Dorsal surfaces of head, trunk, and limbs and lateral surfaces of trunk finely shagreened; minute pointed, widely scattered tubercles on dorsum, more numerous posteriorly than anteriorly; supratympanic fold absent; small, subcircular, elevated glandular area in tympanic region posterior to eye and rear end of mandible, bearing large tubercles with pointed keratinous tips; ventral side of head smooth; vocal sac present; gular gland of vocal sac smooth, large and wide, covering about 70 percent of throat width (Fig. 8B); chest smooth, abdomen weakly areolate; ventral side of limbs smooth; short transverse fold above vent. Forelimbs slender;hand large (HND/SVL 0.32); tips of fingers enlarged into large disks, each with circummarginal groove; relative length of fingers: I I 2+/2.25 II 2/3+ III 2.75/2.25 IV; thenar tubercle oval, small and low, about one-fourth length of metacarpal of Finger I; palmar tubercles indiscernible. Hind limbs slender, moderately long; heel reaching to level of eye when legs adpressed forwardly to body; crus moderately long (TibL/SVL 0.48), about as long as thigh; heels meeting each other when knees flexed and thighs held perpendicularly to median plane; foot subequal in length to crus (FoL/TibL 0.96); relative length of toes: I I 2/2.25 II 1.5/3- III 1.75/3 IV 3-/1.75 V (Fig. 8C); inner metatarsal tubercle moderately prominent, elongated, about twothirds length of metatarsus of Toe I; outer metatarsal tubercle small, rounded. Coloration in life. During night, skin on dorsal side of head, trunk, forelimbs, crus and tarsus light yellowishbrown with more or less regular dark brown speckling; indistinct darker brown transverse stripe between upper eyelids; large dark brown, irregularly shaped spot in scapula region, two less distinct, somewhat lighter brown, irregularly shaped spots at level of anterior end of pelvis, separated from each other by half their width; cloacal region with dark brown mottling; dorsal skin of thigh largely unpigmented with only a broad stripe of widely scattered brown pigmentation; weak brown stripe along canthus, continuing behind eye on anterior half of trunk on both sides; tubercles below eye, and in tympanic region at rear end of jaw white; indistinct dark brown stripe running diagonally on middle of tibia, forming interrupted, inverted U-shaped band together with pelvic spots when legs folded against body; ventral side of head, trunk and limbs largely unpigmented and translucent; gular gland bright yellow; fingers and toes yellow (Fig. 7A). During day, basic dorsal coloration brighter, very light brown to bright cream-colored; dark brown dorsal speckles, spots and stripes in more pronounced contrast to basic coloration, more distinctly visible (Fig. 7B). Coloration in preservative. Dorsal basic coloration largely faded to yellowish white; darker dorsal pattern elements light to dark brown, clearly visible; yellow color of gular gland, fingers and toes faded to white (Fig. 8A–C). Variation. The paratypes match the holotype in general appearance, proportions, coloration and color pattern. Mensural variation within the species is shown in Table 1. Pedal webbing variation is I 2+[100]/2.5[90],2.25[10] II 2[50],2+[40],2.25[10]/3[10],3+[40],3.5[50] III 1.75 [80],2-[20]/3[100] IV 3 -[40],3[60]/1.75[100] V. Bioacoustics. Series of advertisement calls of six different males were recorded at the following ambient temperatures: 10.9°C (N = 1), 13.6°C (N = 3), and 16.2°C (N = 2). The advertisement call consisted of five to six, rarely four pulse groups (notes) (Fig. 9). Depending on the ambient temperature, notes were repeated at a rate of 7.1–10.0/s (10.9°C), 8.2–11.7/s (13.6°C), and 10.2–11.4/s (16.2°C). The highest repetition rate was always between the first three notes of a series, the lowest at the end of the series. Each note consisted of 10–11 pulses (Fig. 9). Probably due to echo effects, pulsation was often veiled in the waveforms, especially towards the end of the note. Pulse repetition rate varied from 190–210/s at 10.9°C, 222–250/s at 13.6°C, and 277–292/s at 16.2°C, resulting in a note length of 72–94 ms, 55–70 ms, and 36–50 ms, respectively. Amplitude modulation was prominent within individual notes (Fig. 9). Total call length showed linear temperature dependence and varied from 388–397 ms at 16.2°C, 472–499 ms at 13.6°C, and 572–620 ms at 10.9°C for five-note calls (Fig. 10). Energy maximum showed linear temperature dependence, with 3020–3150 Hz at 10.9°C, 3370–3550 Hz at 13.6°C, and 3660–3810 Hz at 16.2°C (Figs. 9–10). There was no marked frequency modulation. Prominent harmonics were at about 6000–7000 Hz and 9000–11000 Hz (Fig. 9). Ecology and natural history. We collected males and females in swamps in forest openings, or at forest edges (Fig. 11A). Males were found calling above standing bodies of water with thick lower vegetation cover. In Gishwati Forest and Kamiranzovu Swamp in Nyungwe Forest, the species was found calling in syntopy with Hyperolius castaneus and H. discodactylus. One adult male (UTEP 20802) from Kahuzi-Biega National Park (DRC) was found 3.5 meters above ground in montane forest. Tadpoles are unknown. Laurent (1955, 1983) listed the species from bushes in montane forest. Laurent (1982) noted that, in general, the species is common in the foliage of shrubs in dense forests. He also recorded it in banana trees in a deep valley (Nyungwe, Rwanda) and “des trous de prospection” (i.e., prospecting holes likely for gold mining, Upper Lubitshako, Kabobo Plateau, DRC). Etymology. The species epithet derives from the Greek noun φάντασμα (phántasma), meaning ghost or phantom, in allusion to the coloration and general appearance of the new species. The epithet is used as an invariable noun in apposition. Distribution and conservation. The occurrence of the species has been confirmed for several locations in western Rwanda (Nyungwe and Gishwati Forest) and eastern DRC (in and near Kahuzi-Biega National Park, Itombwe Plateau and Kabobo Plateau [Laurent 1982], Fig. 5). We expect the species to be eventually found in the AR of southwestern Uganda and northwestern Burundi. So far, the species has been recorded from only a narrow elevation range between 1962 m (Kamiranzovu Swamp, Rwanda) and ca. 2400 m (May ya Moto [and possibly Luemba], Itombwe Plateau, Laurent 1982). Given the relatively limited overall geographic distribution of the species with an estimated extent of occurrence of 19,088 km 2 (Fig. 5), an estimated area of occupancy of 52 km 2 (both calculated with GeoCAT; Bachman et al. 2011), the detection of the amphibian chytrid fungus in one adult male (UTEP 20791, Greenbaum et al. 2015), and the conservation challenges facing natural areas of the AR (Greenbaum 2017; Ayebare et al. 2018), we categorize this species as Vulnerable under the IUCN Red List criteria (IUCN 2021).

Afrixalus phantasma Dehling, Greenbaum, Kusamba & Portik sp. nov. Ghost Spiny Reed Frog urn:lsid:zoobank.org:act: 1B2DBF26-5B0A-4DA8-B65E-0BC01704C1B4 Afrixalus laevis (nec Megalixalus laevis Ahl 1930)— Laurent 1972: 59 (partim); Laurent 1982: 33 (partim); Schiøtz 1999: 56 (partim); Channing & Howell 2006: 137 (partim); Spawls et al. 2006: 183 (partim); Channing & Rödel 2019: 158 (partim). Holotype. ZFMK 103454 (field no. JMD 723), adult male, from Gishwati Forest (01.823745° S, 29.360373° E, 2084 m), now part of Gishwati-Mukura National Park, Western Province, Rwanda, collected on 5 April 2011 by J. Maximilian Dehling and Bonny Dumbo (Figs. 7A, 8A–C). Paratypes. ZFMK 103455 (field no. JMD 722), adult female, collected with the holotype; ZFMK 103456 (field no. JMD 2015-30), adult male, ZFMK 103457 (field no. JMD 2015-31), adult female, from the type locality in Gishwati Forest, both collected on 27 September 2015 by J. Maximilian Dehling and Bonny Dumbo; ZFMK 103458–60 (field nos. JMD 677–679), three adult males, collected on 19 March 2011 by J. Maximilian Dehling, ZFMK 103461–62 (field nos. JMD 954–955), two adult males, collected on 16 February 2013 by J. Maximilian Dehling, all from Kamiranzovu Swamp (02.477165° S, 29.158243° E, 1962 m), Nyungwe National Park, Western Province, Rwanda; UTEP 20791–20792 (field nos. EBG 2838, 2843), two adult males, collected on 21 December 2009 by Chifundera Kusamba, Wandege M. Muninga, Mwenebatu M. Aristote, and Maurice Luhumyo from Nyakasanza Swamp near Tshibati (02.22886° S, 28.78017° E, 1979 m), South Kivu Province, DRC. Referred specimens. UTEP 20802 (field no. EBG 1198), forest ca. 4 km NW of Lwiro (02.2226° S, 28.7754° E, 2077 m), South Kivu Province, DRC; UTEP 20803, 22418–20 (field nos. EBG 1232, 1238–40), Kahuzi-Biega National Park, Mugaba (02.2750° S, 28.6631° E, 2298 m), South Kivu Province, DRC; UTEP 20804 (field no. EBG 1283), Kahuzi-Biega National Park, Chinya (02.2671° S, 28.6455° E, 2267 m), South Kivu Province, DRC; UTEP 20793–94 (field nos. EBG 2844–45), Nyakasanza Swamp near Tshibati (02.22886° S, 28.78017° E, 1979 m), South Kivu Province, DRC; UTEP 20795–20800, 22421 (field nos. ELI 414–20), Nyakasanza Swamp near Tshibati (02.22829° S, 28.77972° E, 1979 m), South Kivu Province, DRC; UTEP 20801 (field no. ELI 425), Chanjoka (02.21261° S, 28.77644° E, 2115 m), South Kivu Province, DRC. Diagnosis. The species is referred to the genus Afrixalus by exhibiting the following characteristics: fingers and toes webbed; tips of fingers and toes enlarged to discs; eye large; pupil vertically elliptical; tympanum indistinct; vomer ridges and teeth absent; dorsal surfaces finely shagreened with minute pointed tubercles; outer metatarsal tubercle distinct; gular gland in males. It is readily distinguished from most other members of the genus by its small size (SVL in males 20.1–24.6 mm, in females 22.6–26.4 mm), being smaller than A. dorsalis (males 25–28 mm, females 26–30 mm), A. fornasini (males 30–38 mm, females 35–40 mm), A. lacteus (males 22–27 mm, females 25– 29 mm), A. leucostictus (males 27–32 mm, females 25–36 mm), A. manengubensis (males to 32 mm), A. nigeriensis (males 28–34 mm, females 32–35 mm), A. osorioi (males 27–31 mm, females 32–35 mm), A. paradorsalis (males 28–34 mm, females 32–35 mm), A. septentrionalis (males 19–21 mm), and A. wittei (males 27–30 mm, females 29–33 mm); and larger than A. brachycnemis (males 18–21 mm, females 20–22 mm), A. delicatus (males 15–19 mm, females 17–22 mm), A. spinifrons (males to 20 mm, females to 25 mm), and A. stuhlmanni (males 15–21 mm, females 17–25 mm). Its differs in dorsal coloration and pattern from all species with longitudinal stripes or bands on a yellowish-brown background (A. brachycnemis, A. crotalus, A. delicatus, A. dorsalis, A. enseticola, A. fornasini, A. fulvovittatus, A. knysnae, A. morerei, A. orophilus, A. quadrivittatus, A. schneideri, A. spinifrons, A. stuhlmanni, A. upembae, A. septentrionalis, A. vittiger, and A. wittei); species with a conspicuous large dark dorsal blotch on a uniform background on anterior dorsum in combination with large blotches on both sides of the hip (A. leucostictus, A. manengubensis, A. osorioi, A. paradorsalis, and A. schneideri) or with longitudinal lateral dark bands (A. equatorialis and A. nigeriensis); species with a uniformly colored dorsum without conspicuous pattern except a dark dorsolateral stripe (A. aureus, A. clarkei, A. delicatus, A. fornasini, A. lacteus, A. leucostictus [dorsum with small white tubercles], A. uluguruensis, and A. weidholzi [might have a black vertebral line and dark brown flanks]); and from all remaining species having either dark stripes running from tip of snout to back, crossing each other and continuing as dorsolateral stripes (A. vibekensis, also males without asperities); anterior part of dorsum yellowish with brown pattern, posterior part of dorsum translucent (A. laevis, also males without asperities); posterior part of dorsum and dorsal sides of limbs semi-translucent with dense small dark white-edged speckles (A. dorsimaculatus); and dark blotches and transverse marks with white speckles (A. sylvaticus). The advertisement calls of the following species of Afrixalus consist of a long series of clicks, often initiated by a long buzzing note, and thus differ from the call of A. phantasma: A. aureus, A. brachycnemis, A. clarkei, A. crotalus, A. delicatus, A. dorsalis, A. fornasini, A. fulvovittatus, A. knysnae, A. nigeriensis, A. morerei, A. osorioi, A. quadrivittatus, A. septentrionalis, A. spinifrons, A. vibekensis, A. vittiger, A. weidholzi, and A. wittei. The advertisement calls of the remaining species for which information is available differ from the call of A. phantasma in the following characteristics (in parentheses): A. dorsimaculatus (soft, short buzzing rattle, usually repeated three times), A. equatorialis (series of five notes, repeated at 15–20/s and initiated by a long buzz, energy maximum at 2000–2500 Hz), A. lacteus (8–9 notes, 14–15 pulses,>300 pulses/s), A. paradorsalis (2–3 notes, energy maximum at 2700 Hz), A. stuhlmanni (2–9 notes, energy maximum at 4200–5100 Hz), and A. sylvaticus (2–5 notes, energy maximum at 4000–4500 Hz). The new species is most similar to A. lacustris sp. nov. from which it differs by a number of characteristics (see below). Description of holotype. Measurements of the holotype are provided in Table 2. Body very slender, widest at temporal region, slightly tapering to groin (Fig. 8A–C); head small (HL/SVL 0.31, HW/SVL 0.30), about as long as wide (HW/HL 0.98); snout relatively long, rounded in dorsal view and in lateral profile, slightly longer than wide; canthus rostralis hardly distinct, straight between eye and nostril; loreal region oblique; nostrils rounded, directed anterodorsally and slightly laterally; situated much closer to tip of snout and to eye, separated from each other by distance larger than distance between eye and nostril (IN/EN 1.15); eye directed anterolaterally, strongly protruding, very large (ED/HL 0.41), its diameter shorter than snout (ED/SL 0.84); interorbital distance much wider than upper eyelid and wider than internarial distance (IO/IN 1.21); tympanum covered by skin, not visible externally; upper jaw with dentition; teeth on premaxilla larger than teeth on maxilla; choanae small, located far anterolaterally at margins of roof of mouth, its anterior edge covered by maxillary bone, therefore appearing semicircular in ventral view; vomer ridges and teeth absent; tongue short and moderately broad, bilobed for about one-sixth of its length, free distally for about half its length; densely covered with minute papillae; median lingual process absent. Dorsal surfaces of head, trunk, and limbs and lateral surfaces of trunk finely shagreened; minute pointed, widely scattered tubercles on dorsum, more numerous posteriorly than anteriorly; supratympanic fold absent; small, subcircular, elevated glandular area in tympanic region posterior to eye and rear end of mandible, bearing large tubercles with pointed keratinous tips; ventral side of head smooth; vocal sac present; gular gland of vocal sac smooth, large and wide, covering about 70 percent of throat width (Fig. 8B); chest smooth, abdomen weakly areolate; ventral side of limbs smooth; short transverse fold above vent. Forelimbs slender;hand large (HND/SVL 0.32); tips of fingers enlarged into large disks, each with circummarginal groove; relative length of fingers: I I 2+/2.25 II 2/3+ III 2.75/2.25 IV; thenar tubercle oval, small and low, about one-fourth length of metacarpal of Finger I; palmar tubercles indiscernible. Hind limbs slender, moderately long; heel reaching to level of eye when legs adpressed forwardly to body; crus moderately long (TibL/SVL 0.48), about as long as thigh; heels meeting each other when knees flexed and thighs held perpendicularly to median plane; foot subequal in length to crus (FoL/TibL 0.96); relative length of toes: I I 2/2.25 II 1.5/3- III 1.75/3 IV 3-/1.75 V (Fig. 8C); inner metatarsal tubercle moderately prominent, elongated, about twothirds length of metatarsus of Toe I; outer metatarsal tubercle small, rounded. Coloration in life. During night, skin on dorsal side of head, trunk, forelimbs, crus and tarsus light yellowishbrown with more or less regular dark brown speckling; indistinct darker brown transverse stripe between upper eyelids; large dark brown, irregularly shaped spot in scapula region, two less distinct, somewhat lighter brown, irregularly shaped spots at level of anterior end of pelvis, separated from each other by half their width; cloacal region with dark brown mottling; dorsal skin of thigh largely unpigmented with only a broad stripe of widely scattered brown pigmentation; weak brown stripe along canthus, continuing behind eye on anterior half of trunk on both sides; tubercles below eye, and in tympanic region at rear end of jaw white; indistinct dark brown stripe running diagonally on middle of tibia, forming interrupted, inverted U-shaped band together with pelvic spots when legs folded against body; ventral side of head, trunk and limbs largely unpigmented and translucent; gular gland bright yellow; fingers and toes yellow (Fig. 7A). During day, basic dorsal coloration brighter, very light brown to bright cream-colored; dark brown dorsal speckles, spots and stripes in more pronounced contrast to basic coloration, more distinctly visible (Fig. 7B). Coloration in preservative. Dorsal basic coloration largely faded to yellowish white; darker dorsal pattern elements light to dark brown, clearly visible; yellow color of gular gland, fingers and toes faded to white (Fig. 8A–C). Variation. The paratypes match the holotype in general appearance, proportions, coloration and color pattern. Mensural variation within the species is shown in Table 1. Pedal webbing variation is I 2+[100]/2.5[90],2.25[10] II 2[50],2+[40],2.25[10]/3[10],3+[40],3.5[50] III 1.75 [80],2-[20]/3[100] IV 3 -[40],3[60]/1.75[100] V. Bioacoustics. Series of advertisement calls of six different males were recorded at the following ambient temperatures: 10.9°C (N = 1), 13.6°C (N = 3), and 16.2°C (N = 2). The advertisement call consisted of five to six, rarely four pulse groups (notes) (Fig. 9). Depending on the ambient temperature, notes were repeated at a rate of 7.1–10.0/s (10.9°C), 8.2–11.7/s (13.6°C), and 10.2–11.4/s (16.2°C). The highest repetition rate was always between the first three notes of a series, the lowest at the end of the series. Each note consisted of 10–11 pulses (Fig. 9). Probably due to echo effects, pulsation was often veiled in the waveforms, especially towards the end of the note. Pulse repetition rate varied from 190–210/s at 10.9°C, 222–250/s at 13.6°C, and 277–292/s at 16.2°C, resulting in a note length of 72–94 ms, 55–70 ms, and 36–50 ms, respectively. Amplitude modulation was prominent within individual notes (Fig. 9). Total call length showed linear temperature dependence and varied from 388–397 ms at 16.2°C, 472–499 ms at 13.6°C, and 572–620 ms at 10.9°C for five-note calls (Fig. 10). Energy maximum showed linear temperature dependence, with 3020–3150 Hz at 10.9°C, 3370–3550 Hz at 13.6°C, and 3660–3810 Hz at 16.2°C (Figs. 9–10). There was no marked frequency modulation. Prominent harmonics were at about 6000–7000 Hz and 9000–11000 Hz (Fig. 9). Ecology and natural history. We collected males and females in swamps in forest openings, or at forest edges (Fig. 11A). Males were found calling above standing bodies of water with thick lower vegetation cover. In Gishwati Forest and Kamiranzovu Swamp in Nyungwe Forest, the species was found calling in syntopy with Hyperolius castaneus and H. discodactylus. One adult male (UTEP 20802) from Kahuzi-Biega National Park (DRC) was found 3.5 meters above ground in montane forest. Tadpoles are unknown. Laurent (1955, 1983) listed the species from bushes in montane forest. Laurent (1982) noted that, in general, the species is common in the foliage of shrubs in dense forests. He also recorded it in banana trees in a deep valley (Nyungwe, Rwanda) and “des trous de prospection” (i.e., prospecting holes likely for gold mining, Upper Lubitshako, Kabobo Plateau, DRC). Etymology. The species epithet derives from the Greek noun φάντασμα (phántasma), meaning ghost or phantom, in allusion to the coloration and general appearance of the new species. The epithet is used as an invariable noun in apposition. Distribution and conservation. The occurrence of the species has been confirmed for several locations in western Rwanda (Nyungwe and Gishwati Forest) and eastern DRC (in and near Kahuzi-Biega National Park, Itombwe Plateau and Kabobo Plateau [Laurent 1982], Fig. 5). We expect the species to be eventually found in the AR of southwestern Uganda and northwestern Burundi. So far, the species has been recorded from only a narrow elevation range between 1962 m (Kamiranzovu Swamp, Rwanda) and ca. 2400 m (May ya Moto [and possibly Luemba], Itombwe Plateau, Laurent 1982). Given the relatively limited overall geographic distribution of the species with an estimated extent of occurrence of 19,088 km 2 (Fig. 5), an estimated area of occupancy of 52 km 2 (both calculated with GeoCAT; Bachman et al. 2011), the detection of the amphibian chytrid fungus in one adult male (UTEP 20791, Greenbaum et al. 2015), and the conservation challenges facing natural areas of the AR (Greenbaum 2017; Ayebare et al. 2018), we categorize this species as Vulnerable under the IUCN Red List criteria (IUCN 2021)., Published as part of Greenbaum, Eli, Portik, Daniel M., Allen, Kaitlin E., Vaughan, Eugene R., Badjedjea, Gabriel, Barej, Michael F., Behangana, Mathias, Conkey, Nancy, Dumbo, Bonny, Gonwouo, Legrand N., Hirschfeld, Mareike, Hughes, Daniel F., Igunzi, Félix, Kusamba, Chifundera, Lukwago, Wilber, Masudi, Franck M., Penner, Johannes, Reyes, Jesús M., Rödel, Mark-Oliver, Roelke, Corey E., Romero, Soraya & Dehling, J. Maximilian, 2022, Systematics of the Central African Spiny Reed Frog Afrixalus laevis (Anura Hyperoliidae), with the description of two new species from the Albertine Rift, pp. 201-232 in Zootaxa 5174 (3) on pages 213-218, DOI: 10.11646/zootaxa.5174.3.1, http://zenodo.org/record/6986207, {"references":["Ahl, E. (1930) Ueber die afrikanischen Arten der Baumfroschgattung Megalixalus. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin, 1930, 89 - 102.","Laurent, R. F. (1972) Amphibiens. Exploration du Parc National des Virunga, Deuxieme Serie, 22, 1 - 125, 11 pls.","Laurent, R. F. (1982) Le genre Afrixalus Laurent (Hyperoliidae) en Afrique Centrale. Annales du Musee Royal de l'Afrique Centrale, Serie in Octavo, Science Zoologique, 235, 1 - 93.","Schiotz, A. (1999) Treefrogs of Africa. Edition Chimaira, Frankfurt am Main, 350 pp.","Channing, A. & Howell, K. M. (2006) Amphibians of East Africa. Cornell University Press, Ithaca, New York, New York, xi + 418 pp.","Spawls, S., Howell, K. M. & Drewes, R. C. (2006) Pocket Guide to the Reptiles and Amphibians of East Africa. A & C Black Publishers, London, 240 pp.","Channing, A. & Rodel, M. - O. (2019) Field Guide to the Frogs & Other Amphibians of Africa. Struik Nature, Cape Town, 408 pp.","Laurent, R. F. (1955) Apercu de la biogeographie des batraciens et des reptiles de la region des grand lacs. Bulletin de la Societe Zoologique de France, 79, 290 - 310.","Laurent, R. F. (1983) About the herpetofauna of Central African montane forest. In: Rhodin, A. G. J. & Miyata, K. (Eds.), Advances in Herpetology and Evolutionary Biology: Essays in Honor of Ernest E. Williams. Museum of Comparative Zoology, Cambridge, Massachusetts, pp. 350 - 358.","Bachman, S., Moat, J., Hill, A., de la Torre, J. & Scott, B. (2011) Supporting Red List threat assessments with GeoCAT: Geospatial Conservation Assessment Tool. ZooKeys, 150, 117 - 126. https: // doi. org / 10.3897 / zookeys. 150.2109","Greenbaum, E., Meece, J., Reed, K. & Kusamba, C. (2015) Extensive occurrence of the amphibian chytrid fungus in the Albertine Rift, a Central African amphibian hotspot. The Herpetological Journal, 25 (2), 91 - 100.","Greenbaum, E. (2017) Emerald Labyrinth: A Scientist's Adventures in the Jungles of the Congo. ForeEdge, Lebanon, New Hampshire, xv + 329 pp. https: // doi. org / 10.2307 / j. ctv 1 xx 9 krm","Ayebare, S., Plumptre, A. J., Kujirakwinja, D. & Segan, D. (2018) Conservation of the endemic species of the Albertine Rift under future climate change. Biological Conservation, 220, 67 - 75. https: // doi. org / 10.1016 / j. biocon. 2018.02.001","IUCN (2021) IUCN Red List Categories and Criteria: Version 2021 - 3. Available from: https: // www. iucnredlist. org / (accessed 25 May 2022)"]}

Additional file 2: Fig. S1. Structure and RNA-seq analysis of human, chimpanzee, and rhesus PRSSLY pseudogenes. Fig. S2. Phylogenetic analysis of PRSSLY nucleotide sequences. Fig. S3. Confirmation of X-linkage of PRSSLY in marsupials. Fig. S4. Phylogenetic analyses of PRSS family amino acid sequences. Fig. S5. Sequence conservation across PRSSLY gene sequences. Fig. S6. Analysis of synonymous (Ks) and non-synonymous (Ka) substitution rates across PRSSLY. Fig. S7. Expression of human PRSS homologs across tissues. Fig. S8. Gene expression analysis of PRSSLY in purified male germ cells and germ-cell-depleted testis. Fig. S9. Four CRISPR-induced mutations in mouse PRSSLY. Fig. S10. Testis weights of control and Prssly mutant mice. Fig. S11. Testis histology of control and Prssly mutant mice. Fig. S12. Litter sizes in Prssly mutants and controls.

Additional file 5. Sequences used for Ka-Ks analysis of PRSSLY and homologs.

Additional file 9. Sequences and GenBank accession numbers for PRSSLY sequences.

Additional file 1: Table S1 General study characteristics by NANS and TUDA cohorts. Table S2 Blood pressure and use of antihypertensive drugs in adults 18–70 years by MTHFR genotype.

We propose a taxonomy and terminology for rendering engineers to use in describing the main categories of mathematical lobes that are combined to implement bidirectional scattering distribution functions (BSDFs). Bringing consistent language to this area will increase clarity in API names, textbooks, and scholarly publications. We developed this taxonomy and terminology for consistency across our own upcoming works. The taxonomy corresponds to the major BSDF implementation branches in a renderer, rather than surface appearance, and is consistent with physical considerations. The terminology aligns as closely as possible with previous work in rendering and adjacent fields, while resolving inconsistencies among them. The taxonomy is not intended for art direction, machine vision research, optics, material/lighting engineering, or other areas where the critical distinctions between materials differ from those needed by a renderer., Workshop on Material Appearance Modeling, Material Appearance Modeling Community Infrastructure, 25, 28, Morgan McGuire, Julie Dorsey, Eric Haines, John F. Hughes, Steve Marschner, Matt Pharr, and Peter Shirley

Let $k,n \geq 2$ be integers. A compact complex manifold $M$ of dimension $d \geq 1$ is called a generalized Fermat manifold of type $(d;k,n)$ if there is a Galois holomorphic branched covering $π:M \to {\mathbb P}^{d}$, with deck group ${\mathbb Z}_{k}^{n} \cong H2$, it is known that $H$ is the unique generalized Fermat group of type $(1;k,n)$. If $2 \leq n \leq d$, then we observe that $n=d$ and that $M={\mathbb P}^{d}$. If $n \geq d+1$ and $d \geq 2$, then (i) we provide explicit equations for $M$, in terms of the branch hyperplanes (as a suitable fiber product of Fermat hypersurfaces of degree $k$ and dimension $d$) and (ii) we prove that $M$ has a unique generalized Fermat group of type $(d;k,n)$, for $(d;k,n) \notin \{(2;2,5), (2;4,3)\}$. This also permits us to describe the (coarse) moduli space as a complex orbifold, this is of dimension $d(n-d-1)$ given as a quotient $X_{n}/{\mathfrak S}_{n+1}$, where $X_{n}$ is a domain in ${\mathbb C}^{d(n-d-1)}$., minor corrections from previous version

Hughes, Daniel F., Meshaka, Jr, Walter E. (2018): Life history of the Rio Grande leopard frog (Lithobates berlandieri) in Texas. Journal of Natural History 52 (33-34): 2221-2242, DOI: 10.1080/00222933.2018.1526983, URL: http://dx.doi.org/10.1080/00222933.2018.1526983

n/a

Exposure to the metalloid arsenic is a daily occurrence because of its environmental pervasiveness. Arsenic, which is found in several different chemical forms and oxidation states, causes acute and chronic adverse health effects, including cancer. The metabolism of arsenic has an important role in its toxicity. The metabolism involves reduction to a trivalent state and oxidative methylation to a pentavalent state. The trivalent arsenicals, including those methylated, have more potent toxic properties than the pentavalent arsenicals. The exact mechanism of the action of arsenic is not known, but several hypotheses have been proposed. At a biochemical level, inorganic arsenic in the pentavalent state may replace phosphate in several reactions. In the trivalent state, inorganic and organic (methylated) arsenic may react with critical thiols in proteins and inhibit their activity. Regarding cancer, potential mechanisms include genotoxicity, altered DNA methylation, oxidative stress, altered cell proliferation, co-carcinogenesis, and tumor promotion. A better understanding of the mechanism(s) of action of arsenic will make a more confident determination of the risks associated with exposure to this chemical.

BACKGROUND: With no effective treatments for cognitive decline or dementia, improving the evidence base for modifiable risk factors is a research priority. This study investigated associations between risk factors and late-life cognitive decline on a global scale, including comparisons between ethno-regional groups. METHODS AND FINDINGS: We harmonized longitudinal data from 20 population-based cohorts from 15 countries over 5 continents, including 48,522 individuals (58.4% women) aged 54-105 (mean = 72.7) years and without dementia at baseline. Studies had 2-15 years of follow-up. The risk factors investigated were age, sex, education, alcohol consumption, anxiety, apolipoprotein E ε4 allele (APOE*4) status, atrial fibrillation, blood pressure and pulse pressure, body mass index, cardiovascular disease, depression, diabetes, self-rated health, high cholesterol, hypertension, peripheral vascular disease, physical activity, smoking, and history of stroke. Associations with risk factors were determined for a global cognitive composite outcome (memory, language, processing speed, and executive functioning tests) and Mini-Mental State Examination score. Individual participant data meta-analyses of multivariable linear mixed model results pooled across cohorts revealed that for at least 1 cognitive outcome, age (B = -0.1, SE = 0.01), APOE*4 carriage (B = -0.31, SE = 0.11), depression (B = -0.11, SE = 0.06), diabetes (B = -0.23, SE = 0.10), current smoking (B = -0.20, SE = 0.08), and history of stroke (B = -0.22, SE = 0.09) were independently associated with poorer cognitive performance (p < 0.05 for all), and higher levels of education (B = 0.12, SE = 0.02) and vigorous physical activity (B = 0.17, SE = 0.06) were associated with better performance (p < 0.01 for both). Age (B = -0.07, SE = 0.01), APOE*4 carriage (B = -0.41, SE = 0.18), and diabetes (B = -0.18, SE = 0.10) were independently associated with faster cognitive decline (p < 0.05 for all). Different effects between Asian people and white people included stronger associations for Asian people between ever smoking and poorer cognition (group by risk factor interaction: B = -0.24, SE = 0.12), and between diabetes and cognitive decline (B = -0.66, SE = 0.27; p < 0.05 for both). Limitations of our study include a loss or distortion of risk factor data with harmonization, and not investigating factors at midlife. CONCLUSIONS: These results suggest that education, smoking, physical activity, diabetes, and stroke are all modifiable factors associated with cognitive decline. If these factors are determined to be causal, controlling them could minimize worldwide levels of cognitive decline. However, any global prevention strategy may need to consider ethno-regional differences.

Analytic and computational micromechanics techniques based on the composite cylinders method and the finite element method, respectively, have been used to determine the effective coefficient of thermal expansion (CTE) of carbon nanotube-epoxy nanocomposites containing aligned nanotubes. Both techniques have been used in a parametric study of the influence of interphase stiffness and interphase CTE on the effective CTE of the nanocomposites. For both the axial and transverse CTE of aligned nanotube nanocomposites with and without interphase regions, the computational and analytic micromechanics techniques were shown to give similar results. The Mori-Tanka method has been used to account for the effect of randomly oriented fibers. Analytic and computational micromechanics techniques have also been used to assess the effects of clustering and clustering with interphase on the effective CTE components. Clustering is observed to have a minimal impact on the effective axial CTE of the nanocomposite and a 3-10%. However, there is a combined effect with clustering and one of the interphase layers. Master of Science

Studies of Y chromosome evolution often emphasize gene loss, but this loss has been counterbalanced by addition of new genes. The DAZ genes, which are critical to human spermatogenesis, were acquired by the Y chromosome in the ancestor of Old World monkeys and apes. We and our colleagues recently sequenced the rhesus macaque Y chromosome, and comparison of this sequence to human and chimpanzee enables us to reconstruct much of the evolutionary history of DAZ. We report that DAZ arrived on the Y chromosome about 38 million years ago via the transposition of at least 1.1 megabases of autosomal DNA. This transposition also brought five additional genes to the Y chromosome, but all five genes were subsequently lost through mutation or deletion. As the only surviving gene, DAZ experienced extensive restructuring, including intragenic amplification and gene duplication, and has been the target of positive selection in the chimpanzee lineage., Charles A. King Trust, Howard Hughes Medical Institute, National Institutes of Health (U.S.)

A coupled solution approach is presented for numerically simulating a near-field underwater explosion (UNDEX). An UNDEX consists of a complicated sequence of events over a wide range of time scales. Due to the complex physics, separate simulations for near/far-field and early/late-time are common in practice. This work focuses on near-field early-time UNDEX simulations. Using the assumption of compressible, inviscid and adiabatic flow, the fluid flow is governed by a set of Euler fluid equations. In practical simulations, we often encounter computational difficulties that include large displacements, shocks, multi-fluid flows with cavitation, spurious waves reflecting from boundaries and fluid-structure coupling. Existing methods and codes are not able to simultaneously consider all of these characteristics. A robust numerical method that is capable of treating large displacements, capturing shocks, handling two-fluid flows with cavitation, imposing non-reflecting boundary conditions (NRBC) and allowing the movement of fluid grids is required. This method is developed by combining numerical techniques that include a high-order accurate numerical method with a shock capturing scheme, a multi-fluid method to handle explosive gas-water flows and cavitating flows, and an Arbitrary Lagrangian Eulerian (ALE) deformable fluid mesh. These combined approaches are unique for numerically simulating various near-field UNDEX phenomena within a robust single framework. A review of the literature indicates that a fully coupled methodology with all of these characteristics for near-field UNDEX phenomena has not yet been developed. A set of governing equations in the ALE description is discretized by a Runge Kutta Discontinuous Galerkin (RKDG) method. For multi-fluid flows, a Direct Ghost Fluid (DGF) Method coupled with the Level Set (LS) interface method is incorporated in the RKDG framework. The combination of RKDG and DGF methods (RKDG-DGF) is the main contribution of this work which improves the quality and stability of near-field UNDEX flow simulations. Unlike other methods, this method is simpler to apply for various UNDEX applications and easier to extend to multi-dimensions. Ph. D.

Ship motions in a seaway have long been of great importance, and today with advanced hull forms and higher speeds they are as important as ever. While one can now often adequately predict heave, pitch, sway, yaw and even surge, roll motions are much more difficult. Roll is the one motion that is very dependent upon viscous effects of the fluid. Recently, at David Taylor Model Basin, there have been model experiments where the bilge keels were instrumented in order to directly measure their damping force upon the vessel. To build upon this work and to validate it when applied to full scale vessels, a trial using the Italian naval vessel Nave Bettica was performed. The objective of this thesis is to describe the experiment, present and analyze the results, and offer some conclusions based upon these results. The process of instrumenting the port bilge keel using strain gages and correlating their output to pressures and total forces is described. Selected results for different forward speeds are presented, with full results in the appendices. Particle image velocimetry (PIV) was also performed during the test and was used to measure the flow field in a three foot by three foot area under the aft end of the same bilge keel. Selected image series are presented, as is a methodology for using these images to calculate the center of pressure and the corresponding results. Master of Science

An efficient interaction formula and a semi-analytical method are developed for calculating the ultimate strength of steel-elastomer sandwich panels under combined in-plane compression and lateral pressure. By using the Galerkin method and extending the semi-analytical method to clamped sandwich panels, the governing equations of sandwich panels have been solved by the Galerkin method. The material nonlinearity is treated by iteration and a three-dimensional mesh. For the load case of pure lateral pressure, the ultimate strength from the semi-analytical method is similar to that from hinge line theory and finite element analysis (FEA). However, the semi-analytical method requires about as much computation as FEA, and it is therefore not suitable for design. Finite element modeling and nonlinear analysis are performed to calculate the ultimate strength of sandwich panels under combined load. The results agree with experimental results. This verifies the accuracy of the current finite element model. The verified finite element model is used to obtain the results for a large set of sandwich panels with various dimensions and load combinations. The FEA results for pure lateral pressure load cases are used to derive a correction factor for the hinge line formula. Statistical analysis confirms that the generalized hinge line formula gives accurate values of ultimate strength of sandwich panels under pure lateral pressure. Except for the pressure-only FEA data points, the other FEA data points are corrected so as not to count the in-plane load carried by the elastomer core. Based on the corrected FEA data points, a general expression is developed for an interaction equation. The resulting equation has a bias of -0.003 and a standard deviation of 0.029. Since the radius of the interaction curve is close to 1, this standard deviation is of the order of 3%, which shows that the ultimate strength given by the equation is very close to the FEA results. The interaction equation is so simple that the ultimate strength of clamped sandwich panels under combined in-plane compression and lateral pressure can be easily calculated. Ph. D.

This thesis investigates the characteristics of a close proximity underwater explosion and its effect on a ship-like structure. Finite element model tests are conducted to verify and validate the propagation of a pressure wave generated by an underwater explosion through a fluid medium, and the transmission of the pressure wave in the fluid to a structure using the Multi-Material Arbitrary Lagrangian/Eulerian method. A one dimensional case modeling the detonation of a spherical TNT charge underwater is investigated. Three dimensional cases modeling the detonation of an underwater spherical TNT charge, and US Navy Blast Test cases modeling a shape charge and a circular steel plate, and a shape charge and a Sandwich Plate System (SPS) are also investigated. This thesis provides evidence that existing tools and methodologies have some capability for predicting early-time/close proximity underwater explosion effects, but are insufficient for analyses beyond the arrival of the initial shock wave. This thesis shows that a true infinite boundary condition, a modified Gruneisen equation of state near the charge, and the ability to capture shock without a very small element size is needed in order to provide a sufficient means for predicting early-time/close proximity underwater explosion effects beyond the arrival of the initial shock wave. Master of Science

Multi-disciplinary ship synthesis models and multi-objective optimization techniques are increasingly being used in ship design. Multi-disciplinary models allow designers to break away from the traditional design spiral approach and focus on searching the design space for the best overall design instead of the best discipline-specific design. Complex design problems such as these often have high levels of uncertainty associated with them, and since most optimization algorithms tend to push solutions to constraint boundaries, the calculated "best" solution might be infeasible if there are minor uncertainties related to the model or problem definition. Consequently, there is a need to address uncertainty in optimization problems to produce effective and reliable results. This thesis focuses on adding a third objective, uncertainty, to the effectiveness and cost objectives already present in a multi-disciplinary ship synthesis model. Uncertainty is quantified using a "confidence of success" (CoS) calculation based on the mean value method. CoS is the probability that a design will satisfy all constraints and meet performance objectives. This work proves that the CoS concept can be applied to synthesis models to estimate uncertainty early in the design process. Multiple sources of uncertainty are realistically quantified and represented in the model in order to investigate their relative importance to the overall uncertainty. This work also presents methods to encourage a uniform distribution of points across the Pareto front. With a well defined front, designs can be selected and refined using a gradient based optimization algorithm to optimize a single objective while holding the others fixed. Master of Science

This thesis studies the present methods used to predict the ultimate tripping strength of stiffened panels under compressive axial stress. The current methods involve the use of a bifurcation, or eigenvalue, approach to predicting failure stress. The effects of initial transverse eccentricity of the stiffener are ignored using such a method. Six panels were modeled and tested with ABAQUS, a finite element software package, and the results were compared to output from ULSAP, a closed-form ultimate strength analysis program. The ultimate strengths predicted by ABAQUS changed with the influence of initial deflection of the stiffener flange, while the results from ULSAP did not change. This thesis attempts to use beam-column analysis on the imperfect stiffener flange to predict the tripping strength. It was determined that the procedure presented in this thesis does not accurately model the true failure mode of stiffeners in tripping. The resulting ultimate strengths are extremely conservative and neglect the importance of the stiffener web's role in tripping. Future work is recommended to expand on these findings and to incorporate the influence of the stiffener web into a beam-column solution. Master of Science

This thesis investigates the use of the numerical modeling tools LS-DYNA and USA in modeling general far-field underwater explosions (UNDEX) by modeling a three-dimensional box barge that is subjected to a far-field underwater explosion. Past UNDEX models using these tools have not been validated by experiment and most are limited to very specific problems because of the simplifying assumptions they make. USA is a boundary element code that requires only the structural model of the box barge. LS-DYNA is a dynamic finite element code and requires both the structural model and the surrounding fluid model, which is modeled with acoustic pressure elements. Analysis of the box barge problem results finds that the program USA is a valid tool for modeling the initial shock response of surface ships when cavitation effects are not considered. LS-DYNA models are found to be very dependent on the accuracy of the fluid mesh. The accuracy of the fluid mesh is determined by the ability of the mesh to adequately capture the peak pressure and discontinuity of the shock wave. The peak pressure captured by the model also determines the accuracy of the cavitation region captured in the fluid model. Assumptions made in the formulation of the fluid model causes potential inaccurate fluid-structure interaction and boundary condition problems cause further inaccuracies in the box barge model. These findings provide a base of knowledge for the current capabilities of UNDEX modeling in USA and LS-DYNA from which they can be improved in future work. Master of Science

This thesis presents the results of 67 ABAQUS elasto-plastic Riks ultimate strength analyses of cross-stiffened panels. These panels cover a wide range of typical geometries. Uniaxial compression is applied to the panels, and in some cases combined with lateral pressure. For eight of the panels full-scale experimental results are available, and these verified the accuracy of the ABAQUS results. The 67 ABAQUS results were then compared to the ultimate strength predictions from the computer program ULSAP. In all but 10 cases the ULSAP predicted strength is within 30% of the ABAQUS value, and in all but 4 cases the predicted failure mode also agrees with that of ABAQUS. In one case the ULSAP predicted ultimate strength is 51% below the experimental value, and so this case is studied in detail. The discrepancy is found to be caused by the method which ULSAP uses for panels that experience overall collapse initiated by beam-column-type failure. The beam-column method program ULTBEAM is used to predict the ultimate strength of the 61 panels that ULSAP predicts to fail due to overall collapse of the stiffeners and plating which may or may not be triggered by yielding of the plate-stiffener combination at the midspan (Mode III or III-1). ULTBEAM is found to give more accurate results than ULSAP for Mode III or III-1 failure. Future work is recommended to incorporate ULTBEAM into ULSAP to predict the ultimate strength of panels that fail in Mode III or III-1. Master of Science

The overall objective of this thesis is to develop, validate and assess a probabilistic collision damage model to support ongoing work by the Society of Naval Architecture and Marine Engineering (SNAME) Ad Hoc Panel #6 and IMO working groups. It is generally agreed that structural design has a major influence on tanker oil outflow and damaged stability in grounding and collision, but crashworthiness is not considered in present regulations. The proposed methodology provides a practical means of considering structural design in a regulatory framework, and when implemented would improve the safety and environmental performance of ships. This thesis continues the development and applies a Simplified Collision Model (SIMCOL) to calculate damage extent (transverse, vertical and longitudinal) and oil outflow in ship collisions. The primary contribution of this thesis is the development and validation of a theory for the determination of energy absorbed in longitudinal extent of damage, and the implementation of the theory within SIMCOL. SIMCOL is sufficiently fast to be applied to thousands of collision cases as is required for a probabilistic analysis. The following specific tasks were completed using SIMCOL in support of this project: Completed the development of SIMCOL Version 3.0 including: 1) Deformable Bow sub model 2) Implementation and validation of theory for the determination of energy absorbed in longitudinal extent of damage. • Developed the capability to model collision events using LSDYNA. • Validated Virginia Tech LSDYNA ship collision modeling procedure. • Validated SIMCOL using real collision data, and probabilistic collision data for penetrating collisions. Ph. D.

In this thesis improved expressions for elastic local plate buckling and overall panel buckling of uniaxially compressed T-stiffened panels are developed and validated with 55 ABAQUS eigenvalue buckling analyses of a wide range of typical panel geometries. These two expressions are equated to derive a new expression for the rigidity ratio (EIx/Db)CO that uniquely identifies ¡°crossover¡± panels ¨C those for which local and overall buckling stresses are the same. The new expression for (EIx/Db)CO is also validated using the 55 FE models. Earlier work by (Chen, 2003) had produced a new step-by-step beam-column method for predicting stiffener-induced compressive collapse of stiffened panels. An alternative approach is to use orthotropic plate theory. As part of the validation of the new beam-column method, ABAQUS elasto-plastic Riks ultimate strength analyses were made for 107 stiffened panels ¨C the 55 crossover panels and 52 others. The beam-column and orthotropic approaches were also used. A surprising result was that the orthotropic approach has a large error for crossover panels whereas the beam-column method does not. Some possible reasons for this are suggested. Collapse patterns for the crossover panels are studied and classified from von Mises stress distribution at collapse. The collapse mechanism and load-deflection diagrams suggest stable inelastic post collapse behavior for most panels and an abrupt drop in load carrying capacity in only nine of the 55. Master of Science

An efficient beam-column approach, using an improved step-by-step numerical method, is developed in the current research for studying the ultimate strength problems of stiffened panels with two load cases: 1) under longitudinal compression, and 2) under transverse compression. Chapter 2 presents an improved step-by-step numerical integration procedure based on (Chen and Liu, 1987) to calculate the ultimate strength of a beam-column under axial compression, end moments, lateral loads, and combined loads. A special procedure for three-span beam-columns is also developed with a special attention to usability for stiffened panels. A software package, ULTBEAM, is developed as an implementation of this method. The comparison of ULTBEAM with the commercial finite element package ABAQUS shows very good agreement. The improved beam-column method is first applied for the ultimate strength analysis of stiffened panel under longitudinal compression. The fine mesh elasto-plastic finite element ultimate strength analyses are carried out with 107 three-bay stiffened panels, covering a wide range of panel length, plate thickness, and stiffener sizes and proportions. The FE results show that the three-bay simply supported model is sufficiently general to apply to any panel with three or more bays. The FE results are then used to obtain a simple formula that corrects the beam-column result and gives good agreement for panel ultimate strength for all of the 107 panels. The formula is extremely simple, involving only one parameter: the product λΠorth2. Chapter 4 compares the predictions of the new beam-column formula and the orthotropic-based methods with the FE solutions for all 107 panels. It shows that the orthotropic plate theory cannot model the "crossover" panels adequately, whereas the beam-column method can predict the ultimate strength well for all of the 107 panels, including the "crossover" panels. The beam-column method is then applied for the ultimate strength analysis of stiffened panel under transverse compression, with or without pressure. The method is based on a further extension of the nonlinear beam-column theory presented in Chapter 2, and application of it to a continuous plate strip model to calculate the ultimate strength of subpanels. This method is evaluated by comparing the results with those obtained using ABAQUS, for several typical ship panels under various pressures. Ph. D.

The serious consequence of ship collisions necessitates the development of regulations and requirements for the subdivision and structural design of ships so that damage and environmental pollution is reduced, and safety is improved. A simplified collision model (SIMCOL) is currently being developed at Virginia Tech to conduct probabilistic analysis of damage in ship collisions and ultimately optimize ship structural designs to improve crashworthiness. Collision data for validation of SIMCOL is very difficult to obtain, and model testing is very costly. Finite Element Analysis (FEA) provides an alternative to physical validation that can be used to increase confidence and insight in simplified model results. This thesis develops a complete methodology for ship-to-ship collision simulations using the explicit non-linear FE code LS-DYNA3D. Various modeling alternatives are considered. The ability to model a complete ship-to-ship collision is developed incrementally starting with bow collisions with a rigid wall. A super-element (intersection model) approach is considered to increase the calculation speed of bow models. A conventional fine mesh finite element bow model is also developed. Results from both models are compared with each other, and with a closed-form calculation from Pedersen. A fine mesh model is developed for a struck tanker cargo section and integrated in a total ship framework modeling external dynamics and ship-to-ship contact. A series of collision scenarios is simulated using the conventional bow model and a rigid bow model striking a double hull tanker. Results are compared with SIMCOL, DAMAGE, DTU and ALPS/SCOL models. LS-DYNA provides detailed and reasonable results for ship collision analysis and comparison to increase confidence in simplified models. Master of Science

The serious consequences of ship collisions necessitate the development of regulations and requirements for the subdivision and structural design of ships to reduce damage and environmental pollution, and improve safety. Differences in striking ship bow stiffness, draft, bow height and shape have an important influence on the allocation of absorbed energy between striking and struck ships. The energy absorbed by the striking ship may be significant. The assumption of a "rigid" striking bow may no longer hold good and typical simplifying assumptions may not be sufficient. The bow collision process is simulated by developing a striking ship bow model that uses Pedersen's super-element approach and the explicit non-linear FE code LS-DYNA. This model is applied to a series of collision scenarios. Results are compared with conventional FE model results, closed-form calculations, DAMAGE, DTU, ALPS/SCOL and SIMCOL. The results demonstrate that the universal assumption of a rigid striking ship bow is not valid. Bow deformation should be included in future versions of SIMCOL. A simplified bow model is proposed which approximates the results predicted by the three collision models, closed-form, conventional and intersection elements, to a reasonable degree of accuracy. This simplified bow model can be used in further calculations and damage predictions. A single stiffness can be defined for all striking ships in collision, irrespective of size. Master of Science

The serious consequence of ship collisions necessitates the development of regulations and requirements for the subdivision and structural design of ships to reduce damage and environmental pollution from collision, and improve safety. The on-going revision of IMO regulations on oil outflow performance and damage stability in grounding and collision is focused on a transition to probabilistic performance-based standards. This thesis addresses one aspect of this problem, a simplified collision model sufficient to predict collision damage, and fast enough to be used in probabilistic analysis requiring thousands of collision simulations. The simplified collision model (SIMCOL) developed and evaluated in this thesis is based on a time domain simultaneous solution of external dynamics and internal deformation mechanics. The external sub-model uses a three-degree of freedom system for ship dynamics. The internal sub-model determines reacting forces from side and bulkhead structures using mechanisms adapted from Rosenblatt and McDermott, and absorbed energy by decks, bottoms and stringers calculated using the Minorsky correlation as modified by Reardon and Sprung. SIMCOL is applied to a series of collision scenarios. Results are compared with MIT's DAMAGE, a Danish Technical University (DTU) model and ALPS/SCOL. SIMCOL provides a fast, consistent and reasonable result for ship collision analysis. An actual collision case is used in an initial attempt to validate the model. This research is sponsored by the Society of Naval Architects and Marine Engineers (SNAME) and the Ship Structure Committee (SSC). Master of Science

The goal of this thesis is to develop nontraditional strategies to provide motion control for different engineering applications. We focus our attention on three topics: 1) roll reduction of ships in a seaway; 2) response reduction of buildings under seismic excitations; 3) new training strategies and neural-network configurations. The first topic of this research is based on a multidisciplinary simulation, which includes ship-motion simulation by means of a numerical model called LAMP, the modeling of fins and computation of the hydrodynamic forces produced by them, and a neural-network/fuzzy-logic controller. LAMP is based on a source-panel method to model the flowfield around the ship, whereas the fins are modeled by a general unsteady vortex-lattice method. The ship is considered to be a rigid body and the complete equations of motion are integrated numerically in the time domain. The motion of the ship and the complete flowfield are calculated simultaneously and interactively. The neural-network/fuzzy-logic controller can be progressively trained. The second topic is the development of a neural-network-based approach for the control of seismic structural response. To this end, a two-dimensional linear model and a hysteretic model of a multistory building are used. To control the response of the structure a tuned mass damper is located on the roof of the building. Such devices provide a good passive reduction. Once the mass damper is properly tuned, active control is added to improve the already efficient passive controller. This is achieved by means of a neural network. As part of the last topic, two new flexible and expeditious training strategies are developed to train the neural-network and fuzzy-logic controllers for both naval and civil engineering applications. The first strategy is based on a load-matching procedure, which seeks to adjust the controller in order to counteract the loads (forces and moments) which generate the motion that is to be reduced. A second training strategy provides training by means of an adaptive gradient search. This technique provides a wide flexibility in defining the parameters to be optimized. Also a novel neural-network approach called modal neural network is designed as a suitable controller for multiple-input multiple output control systems (MIMO). Ph. D.

This thesis describes a multidisciplinary design optimization approach to containership design. The method employs widely accepted regression equations for computing resistance, weights, building costs and operating costs. The current regulations governing freeboard and the Coast Guard wind heel criterion are included. The measures of merit used are the required freight rate and the return on investment. The system is flexible enough to allow changes in trade routes, shipyard and port parameters, and fuel costs. The weight-displacement balance is maintained by including draft as a design variable and imposing an equality constraint on weight and displacement rather than introducing an internal loop to calculate draft at each iteration. This speeds up the optimization process. The process takes into account the discrete container stowage issue. The carrying capacity (number of containers) is expressed as a continuous function of the principal dimensions by using a linear response surface fit that in turn makes the objective function continuous. Speed is a design variable. The optimum speed takes into account the compromise required between higher speeds that imply higher revenue and lower speeds that imply lower fuel costs. The optimizer used is the Design Optimization Tools (DOT) program from Vanderplaats Research and Development, Inc. Results employing the three different techniques provided in DOT have been obtained and compared. The optimum ship tends to be the largest ship in terms of length and beam. An optimum speed is identified. The three techniques provided in DOT give fairly consistent results, but once a good optimum point is identified in the design space, the sequential linear programming algorithm is found to be the most consistent method to converge to a local optimum. The objective function is found to be flat in the vicinity of the optimum that indicates that the designer is not confined to a severely restricted design space and has some freedom in designing the optimum ship. Master of Science

To develop a computer tool that will give the best ship design using an optimization technique is one of the objects of the FIRST project. Choosing a containership design as a test case, the Design Optimization Tools (DOT) package is used as the optimization tool. The problem is tackled from the ship owner's point of view. The required freight rate is chosen as the objective function because the most important thing that concerns the ship owner is whether the ship will make a profit or not, and if so, how much profit it can make. DOT, as well as any other numerical optimization tool, only gives an approximation of the optimum design and uses numerical approximation during the optimization. It is very important for the users to formulate carefully the optimization problem so that it will give a stable and reasonable solution. Development of a geometric module and choosing suitable empirical formulas for performance evaluation are also major issues of the project. Master of Science

A hierarchical approach is typically followed in design of consumer products. First, a manufacturer sets performance targets for the whole system according to customer surveys and benchmarking of competitors' products. Then, designers cascade these targets to the subsystems or the components using a very simplified model of the overall system. Then, they try to design the components so that they meet these targets. It is important to have efficient tools that check if a set of performance targets for a component corresponds to a feasible design and determine the dimensions and mass of this design. This dissertation presents a methodology for developing two tools that link performance targets for a design to design variables that specify the geometry of the design. The first tool (called translator A) predicts the stiffness and mass of an automotive joint, whose geometry is specified, almost instantaneously. The second tool (called translator B) finds the most efficient, feasible design whose performance characteristics are close to given performance targets. The development of the two translators involves the following steps. First, an automotive joint is parameterized. A set of physical parameters are identified that can completely describe the geometry of the joint. These parameters should be easily understood by designers. Then, a parametric model is created using a CAD program, such as Pro/Engineer or I-Deas. The parametric model can account for different types of construction, and includes relations for styling, packaging, and manufacturing constraints. A database is created for each joint using the results from finite element analysis of hundreds or thousands of joint designs. The elements of the database serve as examples for developing Translator A. Response surface polynomials and neural networks are used to develop translator A. Stepwise regression is used in this study to rank the design variables in terms of importance and to obtain the best regression model. Translator B uses optimization to find the most efficient design. It analyzes a large number of designs efficiently using Translator A. The modified feasible direction method and sequential linear programming are used in developing translator B. The objective of translator B is to minimize the mass of the joint and the difference of the stiffness from a given target while satisfying styling, manufacturing and packaging constraints. The methodologies for Translators A and B are applied to the B-pillar to rocker and A-pillar to roof rail joints. Translator B is demonstrated by redesigning two joints of actual cars. Translator B is validated by checking the performance and mass of the optimum designs using finite element analysis. This study also compares neural networks and response surface polynomials. It shows that they are almost equally accurate when they are used in both analysis and design of joints. Ph. D.

Finite element analysis of laminated shells using a three-noded flat triangular shell element is presented. The flat shell element is obtained by combining the Discrete Kirchhoff Theory (DKT) plate bending element and a membrane element similar to the Allman element, but derived from the Linear Strain Triangular (LST) element. Though this combination has been employed in the literature for linear static analysis of laminated plates, the results presented are not adequate to ascertain that the element would perform well in the case of static and dynamic analysis of general shells. The element is first thoroughly tested for linear static analysis of laminated plates and shells and is extended for free vibration, thermal, and geometrically nonlinear analysis. The major drawback of the DKT plate bending element is that the transverse displacement is not explicitly defined within the interior of the element. Hence obtaining the consistent mass matrix or the derivatives of the transverse displacement that are required for forming the geometric stiffness matrix is not straight forward. This problem is alleviated by borrowing shape functions from other similar elements or using simple displacement fields. In the present research, free vibration analysis is performed both by using a lumped mass matrix and a so called consistent mass matrix, obtained by borrowing shape functions from an existing element, in order to compare the performance of the two methods. The geometrically nonlinear analysis is performed using an updated Lagrangian formulation employing Green strain and Second Piola-Kirchhoff (PK2) stress measures. A linear displacement field is used for the transverse displacement in order to compute the derivatives of the transverse displacement that are required to compute the geometric stiffness or the initial stress matrix. Several numerical examples are solved to demonstrate the accuracy of the formulation for both small and large rotation analysis of laminated plates and shells. The results are compared with those available in the existing literature and those obtained using the commercial finite element package ABAQUS and are found to be in good agreement. The element is employed for two main applications involving large flexible structures. The first application is the control of thermal deformations of a spherical mirror segment, which is a segment of a multi-segmented primary mirror used in a space telescope. The feasibility of controlling the surface distortions of the mirror segment due to arbitrary thermal fields, using discrete and distributed actuators, is studied. This kind of study was required for the design of a multi-segmented primary mirror of a next generation space telescope. The second application is the analysis of an inflatable structure, being considered by the US Army for housing vehicles and personnel. The tent structure is made up of membranes supported by arches stiffened by internal pressure. The updated Lagrangian formulation of the flat shell element has been developed primarily for the nonlinear analysis of the tent structure, since such a structure is expected to undergo large deformations and rotations under the action of environmental loads like the wind and snow loads. The wind load is modeled as a nonuniform pressure load and the snow load as lumped concentrated loads. Since the direction of the pressure load is assumed to be normal to the current configuration of the structure, it changes as the structure undergoes deformation. This is called the follower action. As a result, the pressure load is a function of the displacements and hence contributes to the tangent stiffness matrix in the case of geometrically nonlinear analysis. The thermal load also contributes to the system tangent stiffness matrix. In the case of the thermal load this contribution is similar to the initial stress matrix and hence no additional effort is required to compute this contribution. In the case of the pressure load, this contribution (called the pressure stiffness) is in general unsymmetric but can be systematically derived from the principle of virtual work. The follower effects of the pressure load have been included in the updated Lagrangian formulation of the flat shell element and have been validated using standard examples in the literature involving deformation-dependent pressure loads. The element can be used to obtain the nonlinear response of the tent structure under wind and snow loads. Ph. D.

A procedure for generating a customized weight function for wing bending material weight of a High Speed Civil Transport (HSCT) is described. The weight function is based on HSCT configuration parameters. A response surface methodology is used to fit a quadratic polynomial to data gathered from a large number of structural optimizations. To reduce the time of performing a large number of structural optimizations, coarse-grained parallelization with a master-slave processor assignment on an Intel Paragon computer is used. The results of the structural optimization are noisy. Noise reduction in the structural optimization results is discussed. It is shown that the response surface filters out this noise. A statistical design of experiments technique is used to minimize the number of required structural optimizations and to maintain accuracy. Simple analysis techniques are used to find regions of the design space where reasonable HSCT designs could occur, thus customizing the weight function to the design requirements of the HSCT, while the response surface itself is created employing detailed analysis methods. Analysis of variance is used to reduce the number of polynomial terms in the response surface model function. Linear and constant corrections based on a small number of high fidelity results are employed to improve the accuracy of the response surface model. Configuration optimization of the HSCT employing a customized weight function is compared to the configuration optimization of the HSCT with a general weight function. Ph. D.