Search

Measuring presence is critical to improving user involvement and performance in Mixed Reality (MR). Presence, a crucial aspect of MR, is traditionally gauged using subjective questionnaires, leading to a lack of time-varying responses and susceptibility to user bias. Inspired by the existing literature on the relationship between presence and human performance, the proposed methodology systematically measures a user's reaction time to a visual stimulus as they interact within a manipulated MR environment. We explore the user reaction time as a quantity that can be easily measured using the systemic tools available in modern MR devices. We conducted an exploratory study (N = 40) with two experiments designed to alter the users’ sense of presence by manipulating place illusion and plausibility illusion. We found a significant correlation between presence scores and reaction times with a correlation coefficient −0.65, suggesting that users with a higher sense of presence responded more swiftly to stimuli. We develop a model that estimates a user's presence level using the reaction time values with high accuracy of up to 80%. While our study suggests that reaction time can be used as a measure of presence, further investigation is needed to improve the accuracy of the model.

A prerequisite to improving the presence of a user in mixed reality (MR) is the ability to measure and quantify presence. Traditionally, subjective questionnaires have been used to assess the level of presence. However, recent studies have shown that presence is correlated with objective and systemic human performance measures such as reaction time. These studies analyze the correlation between presence and reaction time when technical factors such as object realism and plausibility of the object's behavior change. However, additional psychological and physiological human factors can also impact presence. It is unclear if presence can be mapped to and correlated with reaction time when human factors such as conditioning are involved. To answer this question, we conducted an exploratory study ($N=60$) where the relationship between presence and reaction time was assessed under three different conditioning scenarios: control, positive, and negative. We demonstrated that human factors impact presence. We found that presence scores and reaction times are significantly correlated (correlation coefficient of −0.64), suggesting that the impact of human factors on reaction time correlates with its effect on presence. In demonstrating that, our study takes another important step toward using objective and systemic measures like reaction time as a presence measure.

Accuracy of In-Pen Weighing (IPW) Positions, a feature of VYTELLE SENSE (Vytelle LLC, previously GrowSafe Beef), was evaluated using an in-pasture walk-over-weighing (WOW) system (WOW2; Tru-Test Ltd.) as a static-scale proxy. This experiment could provide important information for researchers and producers alike.

Hydrothermal liquefaction (HTL) is a promising technology for the production of biocrude oil from microalgae. Although this catalyst-free technology is efficient under high-temperature and high-pressure conditions, the biocrude yield and quality can be further improved by using heterogeneous catalysts. The design of robust catalysts that preserve their performance under hydrothermal conditions will be therefore very important in the development of biorefinery technologies. In this work, we describe two different synthetic routes (i.e., impregnation and cyclodextrin-assisted one-pot colloidal approach), for the preparation in aqueous phase of six high surface area CoMo/γ-Al2O3catalysts. Catalytic tests performed on the HTL of Nannochloropsis gaditanamicroalga indicate that solids prepared by the one-pot colloidal approach show higher hydrothermal stability and enhanced biocrude yield with respect to the catalyst-free test. The positive effect of the substitution of the block copolymer Tetronic T90R4 for Pluronic F127 in the preparation procedure was evidenced by diffuse reflectance UV–visible spectroscopy, X-ray diffraction, N2-adsorption–desorption, and H2-temperature-programmed reduction measurements and confirmed by the higher quality of the obtained biocrude, which exhibited lower oxygen content and higher-energy recovery equal to 62.5% of the initial biomass.

Temperature plays a primary role in seed germination, and germination under a wide range of temperatures can promote early seedling emergence and stand establishment. The objective of this growth chamber experiment was to determine the effects of temperature (5–35°C) on the germination of eight species using 6 annual and 14 perennial cool‐season grass lots. The greatest germination of annual and perennial cool‐season grasses occurred at 20 and 15°C, respectively. Germination of oat (Avena sativaL.) was typically greatest at 10 to 20°C, whereas rye (Secale cerealeL.) germination was generally greatest at 5 to 20°C and annual ryegrass (Lolium multiflorumLam.) germination was greatest at 10 to 30°C. Germination of orchardgrass (Dactylis glomerataL.) and hardinggrass (Phalaris aquaticaL.) was greatest at 15 to 20°C. Germination of tall fescue [Schedonorus arundinaceus(Schreb.) Dumort.] varied by type: summer‐active tall fescue had optimal germination between 15 and 25°C but summer‐dormant tall fescue had optimal germination between 10 and 20°C, except for ‘NFTF 1800E–’, which was more sensitive to high temperatures (> 5°C). On the basis of these findings, the seeding rates of rye, oat, orchardgrass, hardinggrass, and tall fescue should be increased by ∼30% if planted in early September rather than late September to account for the reduction in germination; summer‐dormant tall fescue should be planted 2 to 3 wk later (1–15 October) than summer‐active types (early September) in the southern Great Plains.

Forage nutritive value analysis is typically performed via laboratory methods. Developing a system that provides crude protein (CP) estimates more quickly would be valuable. For evaluating feasibility of this system, N rate experiments containing bermudagrass [Cynodon dactylon(L.) Pers.], tall fescue [Lolium arundinaceum(Schreb.) Darbysh.], and wheat (Triticum aestivum L.) were examined. A hyperspectral passive spectrometer collecting spectral data at 340 to 1030 nm and a sensor system developed for use from a mobile platform were employed to collect data for prediction of CP. The predicted CP from hyperspectral data regressed with those measured by near‐infrared spectroscopy (NIRS) in a laboratory produced R2= 0.80. Bermudagrass CP predictions from data collected using the mobile system showed no seasonal influence and were characterized with R2= 0.85. Wheat predictions from the mobile sensors exhibited R2= 0.27 for both fall and spring wheat when modeled as one data set. When split into two data sets for fall (Feekes 1–7) and spring (Feekes 7–10) growth, wheat model predictions of CP bore R2= 0.65 and 0.01, respectively. Tall fescue exhibited a similar pattern for mobile data, whereas all predictions regressed with measured values exhibited an R2= 0.63, spring and early summer an R2= 0.83, and fall observations an R2= 0.41. The results of this study indicate prediction of CP using hyperspectral data are accurate enough to be used for reporting forage CP for bermudagrass and are seasonally dependent for reporting forage CP in tall fescue and wheat.

Temperature, in addition to moisture, oxygen, and light, plays an important role in seed germination. Early seedling emergence and stand establishment can be promoted by germination of seeds under a wide range of temperatures; therefore, it is desirable for commercial legume cultivars to germinate over a range of temperatures. The objective of this growth chamber experiment was to determine the effects of temperature on seed germination of seven annual warm‐season and 11 annual cool‐season legumes. Greatest germination of warm‐season and cool‐season legumes occurred at 25 and 20°C, respectively. Germination of warm‐season legumes tended to be maximized at 25°C, while cool‐season legume germination was greatest from 10 to 25°C. Cultivars ‘Rio Verde’ lablab [Lablab purpureus(L.) Sweet] and ‘Whitetail Thicket’ soybean [Glycine sojaSiebold and Zucc. × Glycine max(L.) Merr.] had greater germination than the other entries at 35°C, indicating their potential for use in warmer climates or in delayed planting dates. Additionally, Whitetail Thicket had the greatest germination of summer legume entries at 10°C. The germination of ‘Dixie’ crimson clover (Trifolium incarnatumL.), PI 419238 button medic [Medicago orbicularis(L.) All.], and 600RR and ‘Bulldog 505’ alfalfas (Medicago sativaL.) were less sensitive to temperature than the other cool‐season legume entries. Germination of ‘Devine’ little burr medic (Medicago minimaL.), ‘Armadillo’ burr medic (Medicago polymorphaL.), and ‘Apache’ arrowleaf clover (Trifolium vesiculosumSavi) were severely reduced at temperatures above 30°C.

Choice of stocking method may impact soil, plant, and animal responses. This 3‐yr study evaluated stocking method effects on animal behavior and soil nutrient concentration in ‘Pensacola’ bahiagrass (Paspalum notatumFlügge) pastures. Stocking methods were continuous stocking and rotational stocking with 1‐, 3‐, 7‐, and 21‐d grazing periods and a 21‐d resting period. Responses were measured in three zones based on distance from shade and water (Zone 1, 0–8 m; Zone 2, 8–16 m; Zone 3, >16 m). Indices were calculated to weight number of dung and urine events and time spent by cattle in a zone by the proportion of the total pasture and paddock area represented by that zone. Indices were most uniform (∼1) across zones for rotational stocking with short grazing periods and generally increased linearly in Zones 1 and 2 with increasing grazing period. Except for N, soil nutrient concentration was not affected by stocking method. In zones closest to shade and water, soil nutrients accumulated for all methods in the surface 8 cm but not in the 8‐ to 23‐cm layer. Air temperature, wind speed, and temperature–humidity index explained 49% of the variation in time cattle spent under shade, confirming the importance of the environment in animal behavior. In warm environments, structural features of stocking method (e.g., the position of shade and water) have a greater effect on animal behavior and distribution in the landscape than do stocking density‐mediated effects on competition for forage.

Inclusion of warm‐season forage legumes in livestock grazing systems may increase forage quantity by maintaining the grazing season during dry periods and enhancing nutritive value. Two field experiments were conducted to evaluate forage yield and nutritive value of several warm‐season legumes across different environments and soil pH levels in Oklahoma and Texas. Earn 1 CEU in Crop Managementby reading this article and completing the quiz at www.certifiedcropadviser.org/certifications/self‐study/621.

Switchgrass (Panicum virgatumL.) has potential for both bioenergy and forage. The objectives of this experiment were to (i) determine whether switchgrass could be harvested for greater nutritive value during the vegetative stage relative to early reproductive growth (boot stage); (ii) compare biomass yields of switchgrass harvested once vs. twice per year for bioenergy; and (iii) examine effects of N fertilizer rates on harvest systems. The experiment was a randomized complete block design with a split‐plot arrangement of harvest system treatments as main plot (harvest once per year after frost, harvest twice per year first at vegetative or boot stage, and regrowth after frost) and N fertilizer rate as subplots (0, 90, 180, and 270 kg N ha−1). Biomass yield was greatest and nutrient concentrations were least in the one‐cut system. For the two‐cut system, nutritive values and yields were similar. Total annual biomass increased linearly with N fertilization. Across N rates, crude protein (CP) concentration for the two‐cut systems was 50% greater (71 g kg−1) and acid detergent fiber (ADF) and neutral detergent fiber (NDF) concentrations were 20% lesser (465 and 856 g kg−1, respectively) than switchgrass in the one‐cut system. –Switchgrass harvested at vegetative through boot stage and its regrowth could provide forage of acceptable nutritive value to beef cows. However, greater nutrient removal requires appropriate soil fertility evaluation and fertilizer management for sustainable yields.

Forage dry matter harvested (DMH) and nutritive value (NV) are affected by livestock excreta. Efforts to model nutrient cycling in grazed grasslands would benefit from increased understanding of the duration and spatial pattern of excreta effects on grassland patches. These responses were measured on ‘Pensacola’ bahiagrass (Paspalum notatumFlüggé) swards treated with two excreta types (dung and urine) from two excreta source pastures (Average and High management intensities based on N fertilizer and stocking rates) applied at four frequencies (0, 1, 2, 3 per year) during 2 yr. Forage DMH under dung pats decreased, but DMH surrounding the pat was not affected by application frequency. Suppression of DMH by dung was ≥112 d and extent of suppression increased as application frequency increased. In contrast, DMH under urine increased linearly (2950 to 6250 kg ha−1for the Average management intensity and 3480 to 6450 kg ha−1for the High management intensity) as application frequency increased and effects were observed 15 cm beyond the deposit's edge. Forage NV was not affected by dung, but it increased with increasing urine application frequency and for distances up to 30 cm from the edge of the urine deposit. Urine increased DMH for ≥84 d and increased crude protein for ≥28 d following a single urine application and ≥84 d after multiple applications. Data show that duration and spatial patterns of forage response to dung and urine differ, but effects of both can be long lived and are increased by multiple deposits to a patch.

Livestock excreta deposition in grazed grassland is nonuniform and concentrated around shade, water, and supplement feeding locations. The consequences of repeated dung or urine deposition to grassland patches have not been well quantified in terms of effects on forage dry matter harvested (DMH), forage nutritive value, and nutrient recovery. These responses were measured on ‘Pensacola’ bahiagrass (Paspalum notatumFlüggé) swards treated with two excreta types (dung and urine) from two excreta source pastures (the Average and High management intensities based on N fertilizer and stocking rates) applied at four frequencies (0, 1, 2, 3 yr−1) during 2 yr. Responses were measured within a circular quadrat of radius 45 cm whose center was the midpoint of the excreta deposit. Forage DMH decreased linearly from 3040 to 2800 kg ha−1with increasing dung application frequency and increased from 3040 to 4820 kg ha−1as urine application frequency increased. Forage nutritive value did not differ among dung application frequencies but generally increased with urine application frequency. Nitrogen recovery relative to an untreated control was negative for dung, positive for urine, and decreased with increasing urine application frequency. Forage DMH was suppressed by dung, but urine increased forage DMH, nutritive value, and nutrient removal. Decreasing nutrient recovery with increasing excreta application frequency supports use of grazing strategies that increase uniformity of deposition.

Switchgrass (Panicum virgatumL.) is typically slow and difficult to establish. Field experiments evaluated switchgrass establishment and the response of warm‐season grass weeds (large crabgrass [Digitaria sanguinalis(L.) Scop.], broadleaf signalgrass [Urochloa platyphylla(Munro ex C. Wright) R.D. Webster], Johnsongrass [Sorghum halepense(L.) Pers.], and Texas panicum [Urochloa texana(Buckley) R.D. Webster]) to a preemergence (cloransulam) or postemergence (foramsulfuron, pendimethalin, quinclorac, foramsulfuron + pendimethalin + quinclorac, nicosulfuron, nicosulfuron + pendimethalin + quinclorac, nicosulfuron + quinclorac + atrazine, and monosodium methanearsonate [MSMA]) herbicides. Experimental design was a split‐split‐plot design with presence/absence of preemergence herbicide cloransulam as main plot, weed species as subplot treatment, and postemergence herbicides as sub‐subplot treatments. Herbicides foramsulfuron + pendimethalin + quinclorac was applied at the 1‐ to 2‐ and 2‐ to 3‐leaf stage, whereas nicosulfuron was applied at 2‐ to 3‐leaf stage and nicosulfuron combinations and MSMA were applied at 3‐ to 4‐leaf stage. Using cloransulam as a preemergence herbicide resulted in lower switchgrass seedling numbers and generally did not improve establishment. Interseeding Johnsongrass allowed for the greatest number of switchgrass seedlings and was the least competitive weed, whereas interseeding large crabgrass resulted in the least amount of switchgrass and proved to be the most competitive weed. Foramsulfuron + pendimethalin + quinclorac resulted in effective weed control (>70%) for all four species evaluated and improved switchgrass establishment (13–26%) compared to the untreated control (0–3%); however, greater improvement in stand establishment is needed.

Transportation behavior appears to have shifted in recent years. Between the 2001 and 2009 National Household Travel Surveys, the average annual vehicle miles traveled for all age brackets fell. This reduction in driving is likely to be related to a number of factors, one of which may be the rapid introduction and adoption of information and communication technologies (ICTs) over this period. This paper builds a framework that analyzes the extent to which recent studies and reports have been able to establish a link between the use of new technologies and changes in transportation behavior. The paper also attempts to establish whether there is a difference in the intensity and manner of technology use between age cohorts and in the manner in which technology use affects transportation behavior. Finally, the paper assesses major gaps in the current understanding of how ICTs may affect travel behavior.

Cool‐season legumes have potential to replace N fertilizer in annual cool‐season grass pastures, thus improving returns to producers. The objective of this 3‐yr study was to compare the performance and economics of stocker cattle (Bosspp.) grazing rye (Secale cerealeL.)–annual ryegrass (Lolium multiflorumLam.) under two N systems. Paddocks were planted in early September 2008 through 2010 and contained rye–annual ryegrass with 112 kg N ha−1(fertilized so that a total of soil residual N plus fertilizer N would equal 112 kg N ha−1) (RR‐N) or contained a rye–annual ryegrass with annual legume mixture (arrowleaf clover [Trifolium vesiculosumSavi], field pea [Pisum sativumL.], and hairy vetch [Vicia villosaRoth]) (RR‐Leg). Steers (307 ± 55 kg initial body weight) were weighed every 28 d and stocking rates were adjusted based on forage mass with put‐and‐take steers. Forage mass, forage allowance, and stocker average daily gain (ADG) and total gain (TG) were measured every 28 d. Results show similar performance between RR‐N and RR‐Leg systems in grazing days (average 367 d ha−1), ADG (average 1.065 kg per head d−1), and TG (average 390 kg ha−1). While the 3‐yr average total cost associated with the RR‐N system (US$569.88 ha−1) was greater than the RR‐Leg system ($550.57 ha−1), there were no differences in gross revenue (average $815.91 ha−1) or expected net returns (average $255.68 ha−1) between systems. Annual legumes could be a viable replacement for commercial N fertilizer in rye–annual ryegrass pastures although adoption may be limited due to ease of N fertilizer application.

Use of cool‐season forage legumes may decrease production costs and improve returns to beef cattle (Bosspp.) producers. The objective of this 3‐yr field study was to compare the performance and economics of stocker cattle grazing tall fescue {Festuca arundinaceaSchreb. [syn. Schedonorus arundinaceus(Schreb.) Dumort] ‘Texoma MaxQ II’} under two N systems. Paddocks (0.81 ha) were either a tall fescue with 112 kg N ha−1(fertilized so that a total of soil residual N plus fertilizer would equal 112 kg N ha−1) (TF‐N) or contained a tall fescue with annual legume mixture (arrowleaf clover [Trifolium vesiculosumSavi], hairy vetch [Vicia villosaRoth], and field pea [Pisum sativumL.] (TF‐Leg). Steers (Bos taurus; 282 ± 67 kg initial body weight) were weighed every 28 d during each grazing season, and stocking rates were adjusted based on forage mass with put‐and‐take steers. In each 28‐d grazing period, forage mass, forage allowance, and stocker average daily gain (ADG) and total gain (TG) were measured. Results show a greater number of grazing days (429 and 334 d ha−1, respectively; p= 0.03) were associated with the TF‐N system than the TF‐Leg system while animal performance (ADG of 0.70 kg per head d−1; p= 0.61) and TG (296 and 237 kg ha−1; p= 0.10) were similar. The 3‐yr average total cost with establishment and gross revenue were similar between the TF‐N (US$460.67 and $691.16 ha−1, respectively) and TF‐Leg systems ($466.79 and $553.33 ha−1, respectively). However, the TF‐N system showed a tendency toward greater expected net return than the TF‐Leg system ($224.35 and $92.67 ha−1, respectively; p= 0.08).

Alfalfa (Medicago sativaL.) is a high‐quality forage legume that may have potential to improve net returns to stocker cattle producers in the southern Great Plains. The objective of this 3‐yr field study was to compare the agronomic and economic performance of alfalfa grazing systems under two management strategies. Treatments were (i) continuous stocking for the entire growing season, referred to as full‐season grazing; and (ii) a late‐season rest, which was continuous stocking of alfalfa until 1 August. Steers (250 ± 25 kg initial body weight) were weighed every 28 d during each grazing season, and stocking rates were adjusted with put‐and‐take steers based on forage mass. In each 28‐d grazing period, forage mass and total gain (TG) were measured, allowing calculation of average daily gain (ADG). Animals had ADG of 0.93 and 1.05 kg d−1and TG of 449 and 379 kg ha−1on alfalfa for the full‐season grazing treatment and the late‐season rest (August termination), respectively. The 3‐yr average production cost ($278 ha−1) did not differ between the two management treatments; however, expected net return was greater (P< 0.01) for the full‐season alfalfa grazing treatment ($314 ha−1) compared to the 1 August termination date ($145 ha−1). Therefore, a late‐season rest from grazing was not economically beneficial to grazing alfalfa in this 3‐yr experiment, and grazing alfalfa with summer stockers may be a viable option for producers in the southern Great Plains.

We report cross-linked polycarbosilane (CLPCS) films with superior mechanical properties and insensitivity to moisture. CLPCS are prepared by spin-coating and thermal curing of hexylene-bridged disilacyclobutane (DSCB) rings. The resulting films are siloxane-free and hydrophobic, and present good thermal stability and a low dielectric constant of k= 2.5 without the presence of supermicropores and mesopores. The elastic stiffness and fracture resistance of the films substantially exceed those of traditional porous organosilicate glasses because of their unique molecular structure. Moreover, the films show a remarkable insensitivity to moisture attack, which cannot be achieved by traditional organosilicate glasses containing siloxane bonds. These advantages make the films promising candidates for replacing traditional organosilicate glasses currently used in numerous applications, and for use in emerging nanoscience and energy applications that need protection from moisture and harsh environments.

In previous work, we have found significant differences in the accuracy with which people make initial spatial judgments in different types of head-mounted, display-based immersive virtual environments (IVEs; Phillips, Interrante, Kaeding, Ries, & Anderson, 2010). In particular, we have found that people tend to less severely underestimate egocentric distances in a virtual environment that is a photorealistic replica of a real place that they have recently visited than when the virtual environment is either a photorealistic replica of an unfamiliar place, or a nonphotorealistically (NPR) portrayed version of a familiar space. We have also noted significant differences in the effect of environment type on distance perception accuracy between individual participants. In this paper, we report the results of two experiments that seek further insight into these phenomena, focusing on factors related to depth of presence in the virtual environment. In our reported first experiment, we immersed users (between-subjects) in one of the three different types of IVEs and asked them to perform a series of well-defined tasks along a delimited path, first in a control version of the environment, and then in a stressful variant in which the floor around the marked path was cut away to reveal a 20-ft drop. We assessed participants' sense of presence during each trial using a diverse set of measures, including: questionnaires, recordings of heart rate and galvanic skin response, and gait metrics derived from tracking data. We computed the differences in each of these measures between the stressful and nonstressful versions of each environment, and then compared the changes due to stress between the different virtual environment conditions. Pooling the data over all participants in each group, we found significant physiological indications of stress after the appearance of the pit in all three environments, but we did not find significant differences in the magnitude of the stress response between the different virtual environment locales. We also did not find any significant difference in the level of subjective presence reported in each environment. However, we did find significant differences in gait: participants in the photorealistic replica room showed a significantly greater reduction in stride speed and stride length between the control and pit version of the room than did participants in either the photorealistically rendered nonreplica environment or the NPR replica environment conditions. Our second experiment, conducted with a new set of participants, sought to more directly investigate potential correlations between distance estimation accuracy and personality, stress response, and reported sense of presence, comparatively across different immersive virtual environment conditions. We used pretest questionnaires to assess a variety of personality measures, and then randomly immersed participants (between-subjects) in either the photorealistic replica or photorealistic non-replica environment and assessed the accuracy of their egocentric distance judgments in that IVE, followed by control trials in a neutral, real-world location. We then had participants go through the same set of tasks as in our first experiment while we collected physiological measures of their stress level and tracked their gait, and we compared the changes in these measures between the neutral and pit-enhanced versions of the environment. Finally, we had people fill out a brief presence questionnaire.Analyzing all of these data, we found that participants made significantly greater distance estimation errors in the unfamiliar room environment than in the replica room environment, but no other differences between the two environments were significant. We found significant positive correlation between several of the personality measures, but we did not find any notable significant correlations between personality and presence, or between either personality or presence and gait changes or distance estimation accuracy. These results suggest to us that the relationship between personality, presence, and performance in IVEs is complicated and not easily captured by existing measures.

Selection and identification of better‐adapted annual medics with an appropriate rhizobia inoculum is crucial for improved forage quality and yield. The objectives of this study were to characterize 11 rhizobial strains used for an effectiveness study on annual medics and generate an inoculum blend suitable for annual medic species adapted to the southern Great Plains. Each strain was compared to reference rhizobia strains by polymerase chain reaction (PCR) based on repetitive sequences (rep‐PCR) and ribosomal gene sequences and analyzed for plant growth promoting (PGP) activities. Genetic characterization separated the strains into two groups belonging to Sinorhizobium medicae(seven isolates) and Sinorhizobium meliloti(four isolates). Three of the 11 strains tested positive for the PGP activities of indole acetic acid production and phosphate solubilization. A blend of three strains (NFmix3, consisting of WSM1115, 102F85, and M49), of which two were positive for PGP activities, was used in an effectiveness study for the annual medics Medicago minima(L.) Bartal., Medicago orbicularis(L.) Bartal., Medicago rigidula(L.) All., and Medicago rigiduloidesE. Small. The NFmix3 association with three of the four annual medic species resulted in equivalent biomass production as that of the single specific strain. The NFmix3 blend would be suitable and more economic for use with a mixture of medic species that may provide expansion of the grazing season.

Rhizoma peanut (Arachis glabrataBenth.) has potential to provide high quality forage during summer months; however, establishment of the stand is slow and cold tolerance is limited. During the three growing seasons from 2006 to 2010, a randomized complete block design experiment was initiated at four locations, near Tifton, GA (2006, 2007, and 2008), Gene Autry, OK (2006), Burneyville, OK (2007 and 2008), and Vashti, TX (2007 and 2008), evaluating 16 rhizoma peanut genotypes for better establishment characteristics and cold tolerance. At the end of the establishment year, genotype A6 (PI 210555) had the greatest coverage (74%), followed by genotypes A156 and A160 (51 and 56%, respectively), while genotypes A10 and A42 had the least coverage (9 and 13%, respectively). The remaining genotypes were intermediate and generally did not differ from the released cultivars Florigraze, Arbrook, and Latitude 34, which had 25, 25, and 30% coverage, respectively. In the second season after establishment, genotypes Latitude 34 and A160 produced the greatest yields (1000 and 1360 kg ha−1, respectively). In the third season after establishment, Latitude 34 (3630 kg ha−1) outyielded all genotypes except A156 and A160 (2610 and 2260 kg ha−1, respectively). Therefore genotypes A160 and Latitude 34 consistently had the greatest coverage and production and may have greater cold tolerance. However, in the final year (2010), there were no genotypes that survived the winter.

Annual medics (Medicagospp.) have potential to be important forage legumes in the southern Great Plains of the United States. Currently there are no commercial medic species‐specific rhizobia strains identified for their inoculation. However, commercially available alfalfa (Medicago sativaL.) inoculants may be effective at successfully nodulating annual medics. The objective of this study was to determine the relevant symbiotic rhizobial partner in association with seven annual medics. A greenhouse experiment arranged in three replications of a randomized complete block design quantified rhizobium effectiveness index and shoot and root dry matter (DM) of Medicago arabica(L.) Huds., Medicago lupulinaL., Medicago minima(L.) Bartal., Medicago orbicularis(L.) Bartal., Medicago polymorphaL., Medicago rigidula(L.) All., and Medicago rigiduloidesE. Small when inoculated with five Sinorhizobiumspp. strains (M2, M49, Nitragin A, Nitragin N [a blend of three isolates], and WSM1115) and an untreated control (UTC). Strain M49 was the only strain that effectively nodulated M. rigiduloides, while Nitragin A commercial alfalfa strain was only effective on M. rigidula. Inoculants M2, Nitragin N, and WSM1115 were able to effectively nodulate M. polymorpha, M. arabica, M. minima, and M. orbicularis. To a lesser extent, M. lupulina, M. minima, and M. orbiculariswere also effectively nodulated by Nitragin A alfalfa strain. These data indicate that there are differences in rhizobia specificity of annual medic species, and further research is warranted to improve nodulation of these legumes in the field.

‘Tifton 85’ bermudagrass (Cynodonspp.) is an important forage in the southern United States, but its responses to the interaction of grazing frequency and intensity have not been studied. Sward persistence, herbage accumulation, and nutritive value were measured during 3 yr. Treatments were all combinations of three postgraze stubble heights (SH; 8, 16, and 24 cm) and three regrowth intervals (RI; 14, 21, and 28 d). Short SH (8 cm) with long RI (28 d) or tall SH (24 cm) with short RI (14 d) produced greatest herbage accumulation (11–15 Mg ha−1yr−1). Lowest or nearly lowest herbage accumulation occurred with 14‐d RI and 8‐cm SH or 28‐d RI with 24‐cm SH (7.4–12 Mg ha−1yr−1). Intermediate levels of RI (21 d) or SH (16 cm) produced consistent herbage accumulation regardless of level of the other factor. Nutritive value was primarily affected by RI, and P (3.1 to 2.8 g kg−1), crude protein (CP; 150 to 108 g kg−1), and in vitro digestible organic matter (IVDOM; 602 to 582 g kg−1) concentrations decreased as RI increased. Organic matter and nutrient mass of storage organs increased with increasing SH, but the 24‐cm SH treatment exhibited greater reduction in percentage cover (∼43% units) than the other SH treatments (∼22% units) after 3 yr of grazing. These data indicate that intermediate levels of SH (16 cm) and RI (21 d) provided relatively high Tifton 85 herbage accumulation and nutritive value while minimizing negative impacts on persistence‐related responses.

New bahiagrass (Paspalum notatumFlügge) genotype PCA Cycle 4 is more productive than existing bahiagrass cultivars during the cool season, but it may not persist as well when defoliated frequently or to short stubble. Characterizing tiller dynamics forms a basis for understanding mechanisms of grass yield and persistence responses to defoliation. A 2‐yr field experiment studied the effects of two stubble heights (4 and 8 cm) and two harvest frequencies (7 and 21 d) on tiller dynamics of diploid (PCA Cycle 4, ‘Pensacola’, and ‘Tifton 9’) and tetraploid (‘Argentine’ and Tifton 7) bahiagrass. Tiller number of highly persistent Argentine and Pensacola was unaffected by defoliation treatment and generally greatest among cultivars. Tiller number of Tifton 9 and PCA Cycle 4 varied by up to 970 and 730 tillers m−2, respectively, among defoliation treatments and was greatest with frequent harvests at short stubble. PCA Cycle 4 tiller mass was relatively low. Net tiller appearance rate was positive in spring and early summer, and was nearly zero or negative throughout the remainder of the growing season. This study showed that Tifton 9 and PCA Cycle 4 responded to frequent, close defoliation by increasing tiller number, but tiller mass was the least or not different from the least among entries tested. Very small tillers may indicate a weakening stand under frequent, close defoliation, and management practices such as rotational stocking may be necessary for PCA Cycle 4 to persist.

Differential scanning calorimetry studies of the reaction of a cyclolinear polycarbosilane [cyclo-(CH3Si(CH2)2SiCH3)-(CH2)6]non air-exposed Cu surfaces reveal a substantial enhancement of the cross-linking rate compared to noncatalytic surfaces, e.g., Au, Ag, Al, Si. The increased rate is attributed to surface Cu(II)-catalyzed opening of the embedded disilacyclobutane rings in the polymer. This rate enhancement is used to selectively deposit a cross-linked polycarbosilane on copper patterns in exclusion to the silicon substrate surface. These results could be attractive for realizing metal-dielectric interfaces for applications in nanodevice wiring and packaging.

Integrating low dielectric permittivity (low-k) polymers to metals is an exacting fundamental challenge because poor bonding between low-polarizability moieties and metals precludes good interfacial adhesion. Conventional adhesion-enhancing methods such as using intermediary layers are unsuitable for engineering polymer/metal interfaces for many applications because of the collateral increase in dielectric permittivity. Here, we demonstrate a completely new approach without surface treatments or intermediary layers to obtain an excellent interfacial fracture toughness of >13 J/m2in a model system comprising copper and a cross-linked polycarbosilane with k∼ 2.7 obtained by curing a cyclolinear polycarbosilane in air. Our results suggest that interfacial oxygen catalyzed molecular ring-opening and anchoring of the opened ring moieties of the polymer to copper is the main toughening mechanism. This novel approach of realizing adherent low-kpolymer/metal structures without intermediary layers by activating metal-anchoring polymer moieties at the interface could be adapted for applications such as device wiring and packaging, and laminates and composites.

Bahiagrass (Paspalum notatumFlügge) cultivars are valued for their persistence under grazing and low management inputs. However, they are daylength‐sensitive and have minimal cool‐season production, resulting in high winter feeding costs in forage‐based livestock systems. New germplasm is less daylength‐sensitive, possesses greater cold tolerance, and is more productive during the cool season, but its persistence under defoliation is unknown. A field experiment quantified cover and persistence‐related responses of photoperiod‐sensitive bahiagrass (diploids ‘Pensacola’ and ‘Tifton 9’ and tetraploids ‘Argentine’ and Tifton 7) and a less photoperiod‐sensitive, cold‐adapted (PCA) diploid bahiagrass (Cycle 4) at two stubble heights (4 and 8 cm) and two harvest frequencies (7 and 21 d). Argentine cover was unaffected by defoliation treatments, but harvesting every 7 d to 4 cm for 3 yr resulted in <40% cover for both Tifton 9 and Cycle 4. Averaging over defoliation treatments, stem base mass of Pensacola and Argentine was 60% greater than Cycle 4. At 4‐ and 8‐cm stubble heights, the advantage was 86 and 41%, respectively. When defoliated every 7 d, Pensacola and Argentine stem base mass was 125% greater than Cycle 4, while the difference was 23% for the 21‐d treatment. Similar but less‐pronounced responses were observed for N and total nonstructural carbohydrate (TNC) content of stem base and root + rhizome fractions. Defoliation management of PCA Cycle 4 is more critical than for Pensacola and Argentine bahiagrass, and longer regrowth intervals and taller residual heights may be required to ensure its persistence.

Animal excreta return to pastures plays a major role in nutrient cycling. Improvement in excreta distribution may increase nutrient recovery by pasture plants. Pasture management may modify animal behavior and excreta distribution. This study evaluated the effects of management intensity on animal behavior and soil nutrient concentration in continuously stocked ‘Pensacola’ bahiagrass (Paspalum notatumFlügge) pastures. The three management intensities were: Low (40 kg N ha−1yr−1and 1.4 animal units [AU, one AU = 500 kg live weight] ha−1stocking rate [SR]), Moderate (120 kg N ha−1yr−1and 2.8 AU ha−1SR), and High (360 kg N ha−1yr−1and 4.2 AU ha−1SR). Management intensity did not affect animal behavior (P> 0.05), but it did affect soil nutrient concentration (P≤ 0.10). Surface‐soil N, K, and Mg concentrations were greater at the greatest intensity (P≤ 0.10), but intensity had no effect deeper in the profile (P≥ 0.10). Soil nutrient concentration after 3 yr was generally greatest (P≤ 0.10) closer to shade and water and was associated with a greater proportional time spent and return of excreta by cattle. Increasing air temperature and temperature‐humidity index increased time spent under shade and affected patterns of excreta return (P≤ 0.10). Efforts to increase uniformity of excreta distribution, e.g., movement of portable shade and water troughs, are likely to have greatest impact in warm‐climate areas or during warm seasons in temperate zones.

Bahiagrass (Paspalum notatumFlügge) cultivars are daylength sensitive and have minimal cool‐season production. A new bahiagrass breeding line is less daylength sensitive and more cold tolerant, but its dry matter (DM) yield and nutritive value responses to defoliation treatments are unknown. A 3‐yr field experiment studied effects of two stubble heights (4 and 8 cm) and two harvest frequencies (7 and 21 d) on diploids ‘Pensacola’, ‘Tifton 9’, and the less photoperiod‐sensitive, cold‐adapted (PCA) Cycle 4 bahiagrass; and the tetraploids ‘Argentine’ and Tifton 7. Stubble height had minimal effect on responses measured. When harvested every 7 d, Cycle 4 had the lowest and Argentine the greatest yield (8.4 vs. 11.8 Mg DM ha−1). When harvested every 21 d, Cycle 4 yield was similar to the other diploids (10.6 Mg DM ha−1) and less than the tetraploids (12.6 Mg DM ha−1). Cycle 4 yield distribution was similar to other diploids and generally greater in spring but less in summer than the tetraploids. Across defoliation treatments, Cycle 4 in vitro digestible organic matter (IVDOM) averaged 546 to 562 g kg−1and was greater than all entries in 2006 and all but Tifton 9 in 2005. These data indicate that Cycle 4 was less productive than other bahiagrasses when harvested every 7 d during the warm season, as productive as other diploids at 21‐d harvest intervals, and slightly more digestible than other currently used bahiagrasses. Inferior yield under frequent harvest may imply less defoliation tolerance, thus persistence of PCA Cycle 4 should be studied further.