Search

Suitable air humidity is of great importance for human health, crop growth and the life of buildings. In this work, the polyvinylidene fluoride/calcium chloride (PVDF/Ca[Cl.sub.2]) porous membranes with rich pore structures for adsorption of high-humidity gases were prepared using solvent evaporation-induced phase separation. The results showed that the gap between the PVDF spherical crystals increased with the increase of Ca[Cl.sub.2] content, which increased the porosity of the membrane. When the Ca[Cl.sub.2] content reached 20 wt.%, the water vapor adsorption capacity of the PVDF/Ca[Cl.sub.2] porous membrane was 0.876 [Please download the PDF to view the mathematical expression] and the initial adsorption rate was 0.050 g*[g.sup.-1]*[min.sup.-1]. At this point, the moisture vapor permeance of the membrane was the best at 0.04g*[m.sup.-2]*[h.sup.-1]*[Pa.sup.-1], and the dry strength of the PVDF/Ca[Cl.sub.2] membrane was 0.397 MPa, which was 1.64 times that of the membrane without Ca[Cl.sub.2]. This work provides theoretical and technical guidance for the preparation of air dehumidification materials. Highlights * The porosity of the membranes increased with increasing of calcium chloride content. * The moisture vapor permeance of the M-20 membrane was the best at 0.04 g*[m.sup.-2]*[h.sup.-1]*[Pa.sup.-1]. * The dry strength of the M-20 membrane was 1.64 times that of the M-0 membrane. KEYWORDS Ca[Cl.sub.2], moisture absorption, porous membrane, PVDF, 1 | INTRODUCTION High-humidity gases can be extremely harmful to human health, crop growth and the life of buildings. (1,2) In particular, high-humidity air will speed up the growth and [...]

The objective of this study is to understand how humidity and temperature affect the degradation behavior of polydioxanone (PDO). After changing the degradation environments, we examined the weight loss, pH value, thermal properties, mechanical properties, morphology, and rheological properties of the PDO samples. The specimens were kept in a wet or dry condition for 12 weeks. During degradation, weight retention, pH values, tensile strength, and viscosity decreased, whereas the melting temperature ([T.sub.m]) and degree of crystallinity ([D.sub.c]) increased. Compared with dry samples, wet PDO samples exhibited a higher hydrolysis rate. Also, higher temperatures led to more hydrolysis. Humidity was found to decrease the molecular weight of the samples and increase the degradation rate. KEYWORDS degradation, disk, injection-molding, polydioxanone, rheology, 1 | INTRODUCTION Recently, interest in biodegradable polymers are rising due to the necessity of developing environmentally-friendly polymers. [1] The major advantage of biodegradable polymers is that the products can [...]

Environmental conditions and photoperiod length drive the seasonal variability of gas exchange in plants. Still, little is known about trees' adaptation to climate change, expressed as a delay in decreasing photosynthetic capacity at the end of the growing season. We investigated the effect of elevated air humidity (RH) and sampling period (from July to September) on the variability of net photosynthesis ([A.sub.n]), dark respiration (R), daytime ([g.sub.l_day]) and night-time ([g.sub.l_night]) leaf conductance, an index of leaf chlorophyll content (SPAD), and [A.sub.n]:SPAD ratio in cut shoots of silver birch (Betula pendula Roth). Measurements of cut shoots were conducted in a climate chamber to eliminate the direct effect of field conditions. The [A.sub.n], [A.sub.n]:SPAD ratio, and [g.sub.l_day] were higher in the humidification treatment (H) than in the control (C) (P < 0.05) in autumn. The R was higher in the control than in the humidification treatment across the study period. The [g.sub.l_night] increased considerably in September in both treatments (P < 0.05) and was significantly correlated with R. Our findings suggest that autumnal leaf conductance and gas exchange in silver birch are considerably influenced by long-term exposure to elevated RH and are probably related to a complex of leaf senescence processes, including nitrogen retranslocation. Key words: abscisic acid, global climate change, leaf senescence, night-time, photoperiod. Les conditions environnementales et la duree de la photoperiode influencent la variabilite saisonniere de l'echange gazeux des plantes. Nous en savons toutefois tres peu sur l'adaptation des arbres aux changements climatiques exprimee comme un retard dans la diminution de la capacite photosynthetique a la fin de la saison de croissance. Nous avons examine l'effet de l'humidite elevee de l'air (RH) et la periode d'echantillonnage (de juillet a septembre) sur la variabilite de la photosynthese nette ([A.sub.n]), la respiration nocturne (R), la conductance des feuilles le jour ([g.sub.l_day]) et la nuit ([g.sub.l_night]) et l'indice du contenu de chlorophylle dans les feuilles (SPAD) ainsi que le taux de l'[A.sub.n]:SPAD dans les tiges coupees du bouleau verruqueux (Betula pendula Roth). Les mesures des tiges coupees ont ete effectuees dans une chambre climatique afin d'eliminer l'effet direct des conditions du terrain. L'[A.sub.n], le taux de l'[A.sub.n]:SPAD et le [g.sub.l_day] etaient plus eleves dans l'humidification (H) que dans le traitement (P < 0,05) de controle (C) en automne. La R etait plus elevee dans le controle que dans le traitement d'humidification tout au long de la periode de l'etude. Le [g.sub.l_night] a augmente considerablement en septembre dans les deux traitements (P < 0,05) et etait largement correle avec notre R. Nos conclusions suggerent que la conductance des feuilles automnales et l'echange gazeux dans le bouleau verruqueux sont considerablement influences par l'exposition a long terme a une RH elevee et sont probablement relies a des processus complexes de senescence des feuilles, y compris la retranslocation de l'azote. [Traduit par la Redaction] Mots-cles: acide abscissique, changements climatiques a l'echelle mondiale, senescence des feuilles, periode nocturne, photoperiode., Introduction Global climate change leads to longer growing seasons at high latitudes and is responsible for changes in the functionality and productivity of forest ecosystems. Moreover, climate change creates considerable [...]

In humid tropical environments, where soils are characteristically acidic and low in organic matter, lime and organic residues have been used to improve soil quality. A systematic consideration of their interaction is, therefore, crucial for land-based ecosystem management. A 28-day incubation pot study was carried out to investigate the main and interactive effects of lime and organic residue type (corn stover and vermicompost) on aggregate stability under rapid wetting ([WSA.sub.r]), saturated hydraulic conductivity ([K.sub.sat]), and soil water repellency (SWR) on three acidic soils with contrasting clay content from Trinidad: Cunupia (Aquic Hapludalfs), Sangre Grande (Fluvaquentic Endoaquepts), and Talparo (Aquertic Eutrudepts). Organic residue had a significant (P [less than or equal to] 0.001) increasing effect on [WSA.sub.r] and [K.sub.sat] for all three soils, this being highest for corn stover and lowest for no residue. Lime and organic residue interactive effects were only significant (P [less than or equal to] 0.05) for [WSA.sub.r] in the Cunupia soil, where lime significantly reduced [WSA.sub.r] in the vermicompost and no residue, but not in the corn stover treatment. Soil water repellency increased with clay content and was highest in the lime-corn stover treatment of the Talparo soil. Overall, our results suggest that applying crop residue with lime may help minimise the short-term deleterious effects of lime on the structural and hydraulic properties of humid tropical soils. Nonetheless, future experiments with a wider range of soils and organic residues need to be carried out for a longer term to validate our results. Keywords: acid soils, aggregate stability, crop residue, lime, repellency, soil management, soil organic matter, vermicompost., Introduction Soil acidity is a major limitation to crop production throughout the Caribbean and the world. In the humid tropics, where acid soils are abundant, soils are susceptible to slaking [...]

This research investigated early hyphal development of cucurbit powdery mildew (Podosphaera xanthii) on leaves of cucumber (Cucumis sativus L.) acclimatized to different relative humidities to clarify the factors that limit it. Cucumber seedlings were acclimatized to a low (10%) or high (90%) relative humidity (RH) at 30 [degrees]C from germination. When the cotyledons had expanded and the first true leaf had begun to emerge, the plants were inoculated, and initial conidial invasion, hyphal development, and secondary haustorial formation were evaluated. The initial invasion of P. xanthii into the epidermis was slower on the low-RH leaves than on the high-RH leaves, suggesting that structural properties, such as greater leaf mass per area, physically limited the development of P. xanthii. The hyphal development and secondary haustoria of conidia that had successfully infected the epidermis were also slower on the low-RH leaves. These post-invasion behaviors indicate that conidial development was also suppressed by nonstructural properties of low-RH leaves such as nutrients, which correlate with nonstructural defense. The reduced leaf N content of the low-RH leaves may in part have inhibited the post-invasion behaviors of P. xanthii. Key words: cucurbit powdery mildew, haustorium formation, initial invasion, leaf structure, leaf nitrogen content, plant--pathogen interactions. Resume : Cette recherche s'est penchee sur le developpement precoce des hyphes de l'oidium des cucurbitacees (Podosphaera xanthii) sur les feuilles de concombres (Cucumis sativus L.) acclimates a differents niveaux d'humidite relative afin de clarifier quels sont les facteurs qui le limitent. Des semis de concombre ont ete acclimates a des niveaux d'humidite relative (HR) faible (10 %) ou eleve (90 %) a 30 [degrees]C pour permettre la germination. Lorsque les cotyledons ont pris de l'expansion et que les premieres feuilles vraies ont commence a emerger, les plants ont ete inocules et l'invasion initiale par les conidies, le developpement des hyphes et la formation des haustories secondaires ont ete evalues. L'invasion initiale de P. xanthii dans l'epiderme etait plus lente chez les feuilles placees sous HR faible que celles placees sous HR elevee, suggerant que les proprietes structurales, comme une masse foliaire par surface plus elevee, limitaient physiquement le developpement de P. xanthii. Le developpement des hyphes et des haustories secondaires des conidies qui avaient infecte avec succes l'epiderme etait aussi plus lent chez les feuilles placees sous HR faible. Ces comportements post-invasion indiquent que le developpement des conidies etait aussi inhibe par des proprietes non-structurales des feuilles placees sous HR faible comme les nutriments, qui correlent avec une defense non-structurale. Le niveau reduit d'azote chez les feuilles placees sous HR faible peut avoir inhibe partiellement les comportements post-invasion de P. xanthii. [Traduit par la Redaction] Mots-cles : oidium des cucurbitacees, formation des haustories, invasion initiale, structure foliaire, contenu foliaire en azote, interactions plante--pathogene., Introduction The development of powdery mildews is influenced by atmospheric humidity, but response to humidity differs among different stages of the life cycle. The colonization, sporulation, and dispersal of powdery [...]

High humidity has a strong influence on the development of numerous diseases affecting the above-ground parts of plants (the phyllosphere) in crop fields and natural ecosystems, but the molecular basis of this humidity effect is not understood. Previous studies have emphasized immune suppression as a key step in bacterial pathogenesis. Here we show that humidity-dependent, pathogen-driven establishment of an aqueous intercellular space (apoplast) is another important step in bacterial infection of the phyllosphere. Bacterial effectors, such as Pseudomonas syringae HopM1, induce establishment of the aqueous apoplast and are sufficient to transform non-pathogenic P. syringae strains into virulent pathogens in immunodeficient Arabidopsis thaliana under high humidity. Arabidopsis quadruple mutants simultaneously defective in a host target (AtMIN7) of HopM1 and in pattern-triggered immunity could not only be used to reconstitute the basic features of bacterial infection, but also exhibited humidity-dependent dyshomeostasis of the endophytic commensal bacterial community in the phyllosphere. These results highlight a new conceptual framework for understanding diverse phyllospherebacterial interactions., Author(s): Xiu-Fang Xin [1]; Kinya Nomura [1]; Kyaw Aung [1, 2]; Andr C. Velsquez [1]; Jian Yao [1]; Freddy Boutrot [3]; Jeff H. Chang [4]; Cyril Zipfel [3]; Sheng Yang [...]

QUESTION: How can camels help us monitor humidity? ANSWER: Camels have an unusual ability to retain water in arid locations, thanks to their specially designed noses. A group of researchers [...]

The study investigated the effects of exposure to increased relative air humidity (RH) on stomatal morphology and sensitivity to stomata closure inducing stimulus (low RH) in hybrid aspen (Populus tremula L. x P. tremuloides Michx.) coppice growing in field conditions. Artificially elevated RH reduced air vapour pressure deficit by 5%-10% and altered stomatal sensitivity; trees grown under high RH exhibited stronger stomatal response to decreasing air humidity. We found no difference in mean stomatal pore length between treatments and a small decline in stomatal density under humidification. The lack of correlation between stomatal sensitivity and morphological traits suggests that stomatal sensitivity was unaffected by stomatal morphology. In light of rising atmospheric humidity predicted for high latitudes, strict stomatal control over water loss might be beneficial for trees if drought events become more frequent in the future. However, our experiment revealed that about two-thirds of the leaf-to-air vapour pressure difference ([VPD.sub.L]) response curves demonstrated the opposite pattern, i.e., stomatal opening in response to increasing [VPD.sub.L]. Strict stomatal regulation is probably not beneficial to fast-growing aspen coppice under low RH, as this trait may restrict their carbon gain and growth rate. Key words: climate change, coppice, free air humidity manipulation, isohydric behaviour, stomatal sensitivity, vapour pressure difference. L'etude a examine les effets d'une exposition a une humidite relative (HR) de l'air accrue sur la morphologie des stomates et leur sensibilite a un stimulus qui induit leur fermeture (faible HR) chez le tremble hybride (Populus tremula L. x P. tremuloides Michx.) en taillis, cultive en conditions de terrain. Une HR elevee artificiellement reduisait le deficit en pression de vapeur de l'air de 5-10 % et modifiait la sensibilite des stomates; les stomates des arbres cultives en presence d'une HR elevee repondaient davantage a une diminution de l'humidite de l'air. Les auteurs ont trouve qu'il n'y avait pas de difference de la longueur moyenne des stomates entre les traitements et une legere diminution de la densite des stomates lors d'une humidification. L'absence de correlation entre la sensibilite des stomates et les traits morphologiques suggere que la sensibilite des stomates n'est pas affectee par leur morphologie. Dans la perspective d'un accroissement de l'humidite atmospherique predit dans les latitudes elevees, un controle strict des stomates en fonction de la perte en eau pourrait etre benefique aux arbres si des periodes de secheresse deviennent plus frequentes dans l'avenir. Cependant, les experiences des auteurs ont revele qu'environ les deux tiers des courbes de reponse feuille vs. difference de pression de vapeur dans l'air ([VPD.sub.L]) presentaient le patron oppose, c'est-a-dire une ouverture des stomates en reponse a une augmentation de la [VPD.sub.L]. Une regulation stricte des stomates n'est probablement pas benefique aux taillis de trembles a croissance rapide en condition de HR faible, car ce trait pourrait limiter leur gain en carbone et leur taux de croissance. [Traduit par la Redaction] Mots-cles: changement climatique, taillis, manipulation de l'humidite libre de l'air, comportement iso-hydrique, sensibilite des stomates, difference de pression de vapeur., Introduction Short-rotation coppice of fast-growing woody plants is an efficient cultivation practice with many positive features (Hartwich et al. 2014). As the need for renewable energy increases, we can expect [...]

The ecological nesting requirements of Northern Black Swifts (Cypseloides niger borealis) have been well documented, but little information exists regarding the microclimate at Black Swift nests. We placed 42 data loggers at 10 occupied Black Swift colonies between 2006 and 2010 to measure and record temperature and relative humidity, resulting in 19,181 usable records. Median temperature and relative humidity at nine Colorado and New Mexico sites were 9.4°C and 89.7%, respectively, and at one California site were 13.4°C and 92.8%, respectively. Values were quite stable throughout the breeding season with slight changes reflecting the ambient temperature and humidity of the surrounding macroclimate. These baseline data may prove useful for conservation of this species, especially if predicted global climate changes occur., The microclimate at Northern Black Swift (Cypseloides niger borealis) nests is believed to be an important requirement for nest-site selection but there is a paucity of information on temperature and, [...]

The effects of upstream relative humidity (RH) on low-level wind and precipitation patterns for low-speed, statically stable flows over a mountain are investigated using idealized two- and three-dimensional numerical-simulation experiments in which RH is increased from 0% to 100%. For RH less than some critical threshold, the flow upstream becomes less decelerated as RH is increased; for RH greater than this threshold, the flow upstream becomes more decelerated as RH is increased. This increasing deceleration with RH is due to locally enhanced static stability resulting from enhanced condensation near the freezing level. Analyses from the simulations indicate that the lifted condensation level and the height of the freezing level are significant control parameters for the upstream-flow deceleration in the steady-state solutions. Dimensional analysis using these control parameters (as well as others) brings forth new nondimensional parameters that are shown to enter into analytic formulas for the orographic upstream-flow deceleration in a moist atmosphere.

The influence of land surface heterogeneity on potential cloud formation is investigated using relative humidity as an indicator. This is done by performing numerical experiments using a large-eddy simulation model (LES). The land surface in the model was divided into two patches that had the same sum of latent and sensible heat flux but different Bowen ratios to simulate heterogeneous land surfaces. For heterogeneity in the meso-[gamma] scale (2-20 km), sensitivity analyses were carried out on the heterogeneity amplitude (Bowen ratio difference between contrasting areas) and the inversion strength of potential temperature and specific humidity. The competition between absolute temperature decrease by ABL growth and dry air entrainment in heterogeneous conditions is analyzed using the LES results. First, it is shown that entrainment is located and enhanced over patches with higher Bowen ratios (warm patches) than their surroundings (cold patches). The heterogeneity-induced strong thermals can further penetrate the inversion at the ABL top, thereby reaching lower absolute temperatures than in homogeneous conditions. Second, because of the heterogeneity-induced circulations the moisture is located over the warm patch, and higher timeaveraged RH values at the ABL top ([RH.sub.zi]) than over the cold patches are found here, even for dry atmospheres. These [RH.sub.zi] exceed values found over homogeneous land surfaces and are an indication that surface heterogeneity may facilitate cloud formation. In vertical profiles of RH, few differences are found between the homogeneous and heterogeneous cases, but the essential heterogeneity-induced modifications are within the domain variability.

Two experiments were conducted to investigate the physiological responses of Bos taurus (Angus cross, n = 6) and Bos indicus (Brahman, n = 6) cattle to prolonged heat and humidity, as can occur during live export by sea. Each experiment was carried out in climate-controlled rooms, where heifers were exposed to 15 d of sustained heat and humidity. The treatment was designed to be representative of a long-haul, live-export voyage leaving a southern Australian winter and traveling to a Middle Eastern summer. Wet bulb temperature (WBT) was used to give a combined measure of dry bulb temperature and relative humidity and was increased over several days, culminating in 5 d at 32[degrees]C WBT between d 7 and 11. By d 11, the respiratory rate and core body temperature increased (P < 0.001) compared with values at lower ambient temperature on d 1 and 2 when climate-controlled rooms were not operating. Feed intake of Bos taurus was reduced (P < 0.001) by d 11, whereas that of Bos indicus did not change (P = 0.14). Despite no diurnal variation in climatic conditions, core body temperature of both Bos taurus and Bos indicus continued to show a circadian amplitude of approximately 1[degrees]C throughout the hottest period. This amplitude increased during the recovery period after heat was removed (up to 1.8[degrees]C for Bos indicus and 1.6[degrees]C for Bos taurus). Water intake for both Bos taurus and Bos indicus increased when WBT increased (P < 0.01 on d 11). Significant acid-base and blood electrolyte imbalances occurred in both Bos taurus and Bos indicus, with changes in Bos taurus being more substantial and prolonged. The increase in respiratory rate coincided with a decrease in the partial pressures of carbon dioxide and bicarbonate in venous blood. However, during the hottest period, average daily venous blood pH remained unchanged. When the heat load was reduced after d 11, the blood pH decreased, indicating metabolic acidosis. Blood pH declined from 7.44 to 7.36 for Bos taurus (P < 0.001) and from 7.44 to 7.38 for Bos indicus (P < 0.001). Other parameters measured include heart rate; packed cell volume; plasma and urine Na, K, and Cl; urine pH; and specific gravity. Our results suggest that Bos taurus cattle experience significant physiological changes during exposure to prolonged and continuous high heat and humidity, with alterations persisting for some days after the heat-stress conditions subside. Bos indicus experience similar but less pronounced physiological changes. Key words: acid-base, Bos indicus, Bos taurus, electrolyte, heat stress, temperature

The effect of heat stress (HS) and grain challenge (GC) on acid-base balance and rumen tissue histology in lambs was investigated using 24 yearling wether lambs (58 [+ or -] 4.5 kg of BW) in a 2 x 2 factorial experiment with repeated measures for day (10, 14, and 17) of sampling. The factors were temperature [thermoneutral zone (TN) vs. HS] and diet (control vs. GC). Lambs were blocked by BW and assigned to 1 of 4 treatments in temperature-controlled rooms: 1) TN (temperature = 18 to 20[degrees]C; relative humidity = 30%; 2) TN + GC; 3) HS (temperature = 35[degrees]C for 9 h/d, 20[degrees]C for 15 h/d; relative humidity = 40%); and 4) HS + GC. Venous blood samples were collected at 1800 on the first day of GC (d 10), in the middle of GC (d 14), and at the end of the trial (d 17) by jugular venipuncture and analyzed for pH, gases, hematocrit, plasma ions, and total protein. After all measurements in live animals were taken on d 17, lambs were slaughtered, and tissue samples were obtained from the ventral sac of the rumen for histological assessment. Except for the concentration of plasma glucose (P = 0.04) and total protein (P < 0.01), there were no (P > 0.05) diet x temperature interactions. With HS, the concentration of [Na.sup.+] and [Cl.sup.- in the control group decreased at d 14 and then increased by d 17, and respiration rates in the control group decreased linearly (P < 0.05). Compared with the control group, respiration rates and the concentration of [Cl.sup.-] in the GC lambs increased linearly over time, whereas the concentration of [Na.sup.+] decreased linearly (P < 0.05) across time. Under HS, the partial pressure of carbon dioxide, total carbon dioxide, the partial pressure of oxygen and oxygen saturation, and the concentration of [Mg.sup.2+], glucose, and HC[O.sup.-.sub.3] showed quadratic (P < 0.05) responses with time. In both treatments, DMI, base excess of extracellular fluid, base excess of blood, and standard bicarbonate increased linearly (P < 0.05), and hematocrit, plasma protein, [Ca.sup.2+], anion gap, and plasma strong ion difference decreased linearly (P < 0.05) across day. Compared with the control group, the GC group had decreased papillae count in the ruminal ventral sac (1.3 vs. 1.5; P < 0.05). These results suggest that under HS the acidifying effects of GC on acid-base balance in lambs were counteracted in the short-term through respiratory adaptation. Key words: acid-base balance, grain challenge, heat stress, rumen tissue histology, sheep

From December 1998 through May 2000, seasonal use and selection of caves by salamanders were documented in 93 small caves in Crawford County, Arkansas. Caves were surveyed seasonally between winter 1998-1999 and spring 2000, and the numbers and species of all salamanders present were documented. Cave ambient temperature and relative humidity were recorded. Also, each cave entrance was georeferenced using GPS (Global Positioning System) and landscape-level variables around each entrance were quantified using ArcView GIS (Geographic Information System) data layers. Using salamander and ArcView data, relations between salamander occurrence based upon landscape-level variables (dominant overstory vegetation, geology, slope, aspect, solar radiation and distance to perennial stream) and cave characteristics (ambient temperature, relative humidity, cave length and entrance size) were examined. Six species of salamanders were found during the survey. Eurycea lucifuga (cave salamander), Plethodon albagula (western slimy salamander) and P. angusticlavius (Ozark salamander) were commonly observed. Eurycea lucifuga salamanders were active in caves during spring, summer and autumn. Plethodon albagula were most frequently encountered during the summer and P. angusticlavius were most frequently encountered during spring surveys. Few salamanders of any species were detected during winter surveys. The use of caves by the various species of salamanders was influenced by the landscape-level variables and cave characteristics. However, cave ambient temperature and relative humidity appear to have the most influences of salamander use of caves. Both E. lucifuga and P. albagula were significantly more likely to be found in caves with cooler temperatures in summer and higher relative humidities in autumn. In addition to these factors, the probability of finding E. lucifuga significantly decreased with increasing distance to permanent streams, whereas P albagula was significantly more likely to be found in caves with south and west facing aspects, especially during summer and autumn surveys. There were no significant patterns for P angusticlavius use of caves. Seasonal and spatial patterns of cave use by salamanders were primarily influenced by environmental (temperature and relative humidity) factors and the ecological requirements of the salamanders.

A new derivation of local available energy for a compressible, multicomponent fluid that allows for frictional, diabatic, and chemical (e.g., phase changes) processes is presented. The available energy is defined relative to an arbitrary isothermal atmosphere in hydrostatic balance with uniform total chemical potentials. It is shown that the available energy can be divided into available potential, available elastic, and available chemical energies. Each is shown to be positive definite. The general formulation is applied to the specific case of an idealized, moist, atmospheric sounding with liquid water and ice. The available energy is dominated by available potential energy in the troposphere but available elastic energy dominates in the upper stratosphere. The available chemical energy is significant in the lower troposphere where it dominates the available elastic energy. The total available energy increases with increasing water content.

Fans in the once-glaciated, mountainous landscape of humid-temperate New England preserve a long and unique record of deposition and, thus, of hillslope erosion. By using multiple backhoe trenches and radiocarbon dating of wood and charcoal, we determined the history of five small fans (1900-14,850 [m.sup.3]) that range in age from historic to [greater than or equal to] 13,320 calibrated (cal.) [sup.C] yr B.P. Three fans located on river terraces have depositional records whose ages are limited by the age of the terrace on which they are situated. Two other fans, located in glacial valleys, preserve records that extend back nearly to deglaciation. The stratigraphy of all five fans contains evidence suggesting episodic activity, including scoured surfaces and layers of gravel and cobbles. Periods of little or no activity are indicated by development of now-buried soils. Dated sand and gravel strata in several fans suggest correlative periods of increased sediment yield and by inference, runoff, at ca. 9650-9340 and 69006020 cal. [sup.14]C yr B.P. Soils preserved within at least two of the five fans suggest lower sediment yield at ca. 12,900, ca. 5500, ca. 4300, and ca. 3200 cal. [sup.14]C yr B.P. At least three of the fans aggraded rapidly during the past several hundred years in response to land clearance and disturbance; however, many aggradation and scour events in the Holocene cannot be correlated definitively between fans because of the discontinuous nature of gravel beds and the lack of radiocarbon-datable material in the coarsest strata. Drainage-basin sediment yields implied by the fan volumes and integrated over the Holocene are quite low, [greater than or equal to] 4-11 x [10.sup.3] [kg*km.sup.-2.yr-1]. Sediment yields since settlement by European and other immigrants are several to hundreds of times higher, demonstrating the connections among forest clearance, agriculture, and increased erosion rates of New England hillslopes. Keywords: erosion, fans, New England, radiocarbon dating, Vermont.

The willow-feeding leaf beetle (Galerucella lineola F.) attacks its host plant, tea-leafed willow (Salix phylicifolia L.), heavily in damp habitats, but less so in well-drained soils. To confirm this general observation and to explore the factors affecting habitat and host-plant use by this beetle, we collected data from 12 study sites in Finland during two consecutive years. All sites included three habitats: (1) water, where the willows were growing in permanently waterlogged soils, (2) flood zone, where the willows underwent periods of flooding, and (3) dry zone, where the willows grew in well-drained soils. G. lineola was, on average, 16 times more abundant on willows growing directly from water as compared to willows in well-drained soils nearby. To explain this, we proposed three general hypotheses. (1) The food-quality hypothesis states that the apparently stressed willows growing in waterlogged soils provide superior food for the beetles. (2) The predation hypothesis states that open water surface around the willows in wetlands impedes dispersal of predators providing enemy-free space for the beetles. (3) The climate hypothesis states that wetlands provide better abiotic conditions for the adults, eggs, or larvae of this leaf beetle. These hypotheses were tested by using observational data and by performing both laboratory and field experiments. Contrary to the food-quality hypothesis, adult beetles preferred S. phylicifolia grown in dry habitats both for food and oviposition medium in the laboratory, and produced fewer eggs when fed on willow leaves from wetlands. Consistently, larvae performed poorly on leaves from wetland willows in the laboratory, most probably due to low water content of the leaves, also rich in phenolic secondary compounds and poor in nitrogen. The densities of crawling predators did not differ between the habitats, and the predation experiments revealed no difference in predation pressure between the habitats. However, during a rainless period, the first-instar larvae performed relatively poorly in drier habitats despite the high quality of food. When ramets of S. phylicifolia were exchanged between the habitats the first-instar larvae performed best in sunny wetland habitats on willows originally from dry sites. Spraying with water improved the performance of neonate larvae more on willows growing in dry habitat than on wetland willows. The results show that G. lineola does not attack S. phylicifolia growing in wetlands because of the superior food quality or lower predation pressure, but because of the strong affinity by adult beetles to the moist habitat where also the first-instar larvae, vulnerable to desiccation, usually perform best. An apparently ancestral physiological constraint hinders the beetles from using the best food resources and restricts their occurrence primarily to moist habitat patches with poor quality food and high risk of intraspecific competition. Key words: abiotic habitat; desiccation; enemy-free space; food quality; habitat selection; herbivory; humidity; predation; Salix phylicifolia; secondary chemistry; waterlogging; wetlands;

A semidistributed watershed model is applied over the Mahantango Creek catchment in Pennsylvania to estimate future changes in direct runoff under 22 different climate scenarios. It is shown how different subcatchments of the watershed may respond to possible changes in the precipitation and temperature regimes. Subcatchments with the most unfavorable future runoff responses can be identified where possible changes in land use management practices may be suggested. CE Database keywords: Watersheds; Humidity; Surface runoff; Climatic changes; Land usage; Sensitivity analysis.

Evaporation pans [Class A pan, U.S. Weather Bureau (USWB)] are used extensively throughout the world to measure free-water evaporation and to estimate reference evapotranspiration (E[T.sub.0]). However, reliable estimation of E[T.sub.0] using pan evaporation ([E.sub.pan]) depends on the accurate determination of pan coefficients ([K.sub.pan]). Two equations developed by Frevert et al. in 1983 and Snyder in 1992 to estimate daily [K.sub.pan] values were evaluated using a 23-year climate dataset in a humid location (Gainesville, Florida). The E[T.sub.0] data, calculated using daily [K.sub.pan] values from these equations, were compared to the Food and Agricultural Organization (FAO)-Penman-Monteith (FAO56-PM) method. The two equations resulted in significantly different daily [K.sub.pan] values that produced different daily, monthly, and annual total E[T.sub.0] estimates. The E[T.sub.0] values calculated using Frevert et al.'s 1983 [K.sub.pan] coefficients were in very good agreement with the FAO56-PM method with daily, monthly, and annual mean percent errors (PE) of 5.8, 5.5, and 5.7%, respectively. The daily and annual mean-root-mean-square error (RMSE) of the estimates using this method were as low as 0.33 and 7.3 mm, respectively. Snyder's 1992 equation overestimated FAO56-PM E[T.sub.0] with daily, monthly, and annual mean PEs of 16.3, 13.8, and 13.2%, respectively. The daily and annual mean RMSEs for this method were higher (0.6 and 18 mm) than those obtained with Frevert et al.'s 1983 coefficients. The overestimations with Snyder's 1992 method were highest in the peak E[T.sub.0] month of May and in summer months. The performances of the [K.sub.pan] equations were also evaluated using randomly selected individual years (1979, 1988, 1990, and 1994) of climate data that had different climate characteristics than the 23-year average dataset. Frevert et al.'s 1983 coefficients resulted in good E[T.sub.0] estimates with lower annual mean PEs of 7.0, 0.1, 15.7, and 1.3% for 1979, 1988, 1990, and 1994, respectively, compared to Snyder's 1992 equation, which resulted in considerably higher PEs of 17.6, 9.1, 26.2, and 14.3% in 1979, 1988, 1990, and 1994, respectively. It was concluded that using Frevert et al.'s 1983 equation to calculate daily [K.sub.pan] provided more accurate E[T.sub.0] estimates, relative to the FAO56-PM method, from [E.sub.pan] data compared to Snyder's 1992 equation under the humid-region climatic conditions in this study. The method is very useful in computer calculations of E[T.sub.0] since it does not require 'table lookup' for [K.sub.pan] values. CE Database keywords: Evapotranspiration; Humidity; Evaporation.

A numerical model is developed to estimate global solar irradiance from upper-air humidity. In this model, solar radiation under clear skies is calculated through a simple model with radiation-damping processes under consideration. A sky clearness indicator is parameterized from relative humidity profiles within three atmospheric sublayers, and the indicator is used to connect global solar radiation under clear skies and that under cloudy skies. Model inter-comparisons at 18 sites in Japan suggest (1) global solar radiation strongly depends on the sky clearness indicator, (2) the new model generally gives better estimation to hourly-mean solar irradiance than the other three methods used in numerical weather predictions, and (3) the new model may be applied to estimate long-term solar radiation. In addition, a study at one site in the Tibetan Plateau shows vigorous convective activities in the region may cause some uncertainties to radiation estimations due to the small-scale and short life of convective systems.

Phenotypic plasticity and its contribution to adaptation in Lacerta vivipara are discussed. Reciprocal transplants of juveniles were carried out to test for the genetic or plastic origin of greater body length, lower age at maturity, higher fecundity and smaller neonatal size in humid habitats vs dry ones. Gravid females were taken from four populations that differed in the humidity of the habitats and in the last 2-4 weeks of gestation heat and water availability were varied. Juveniles were released into different populations and families divided. Adaptation to the habitat through genetic specialization was not seen. More study is needed to find out about genetic and long-term maternal effects.