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Background: Eulerian and Lagrangian power‐law formulations are both widely used for computational fluid dynamics (CFD) to predict flow‐induced hemolysis in blood‐contacting medical devices. Both are based on the same empirical power‐law correlation between hemolysis and the shear stress and exposure time. In the Lagrangian approach, blood damage is predicted by tracking both the stress and exposure time along a finite number of pathlines in the domain. In the Eulerian approach, a scalar transport equation is solved for a time‐linearized damage index within the entire domain. Previous analytical work has demonstrated that there is a fundamental problem with the treatment of exposure time in the Eulerian model formulation such that the only condition under which the model correctly represents the true exposure time is in a flow field with no streamwise velocity variation. However, the practical implications of this limitation have yet to be thoroughly investigated. Methods: In this study, we demonstrate the inaccuracy of Eulerian hemolysis power‐law model predictions due to the erroneous treatment of exposure time by systematically considering four benchmark test cases with increasing degrees of flow acceleration: Poiseuille flow through a straight tube, inclined Couette flow, and flow through a converging tube with two different convergence ratios. Results: Compared with Lagrangian predictions, we show that, as flow acceleration becomes more pronounced, the resultant inaccuracy in the Eulerian predictions increases. For the inclined Couette flow case, there is a small degree of flow acceleration that yields a discrepancy in the range of 10% between Lagrangian and Eulerian predictions. For flows with a larger degree of acceleration, as occurs in the converging tube flow cases, the discrepancy is considerably larger (up to 257%). Conclusion: The inaccuracy of hemolysis predictions due to the erroneous treatment of exposure time in the Eulerian power‐law model can be significant when there is streamwise velocity variation in the flow field. These results may partially explain the extremely large variability in CFD hemolysis predictions reported in the literature between Lagrangian and Eulerian models. [ABSTRACT FROM AUTHOR]

Background: The fecal microbiome of healthy horses may be influenced by signalment, diet, environmental factors, and disease. Objectives: To assess the effects of age, breed, sex, geographic location, season, diet, and colitis caused by antibiotic use (antimicrobial‐associated diarrhea [AAD]) and Salmonella infection on fecal microbiota. Animals: Healthy horses (n = 80) were sampled from nonhospital environments across multiple geographical locations in the United States. Horses with AAD (n = 14) were defined as those that developed diarrhea secondary to antimicrobial use. Horses with Salmonella infection (n = 12) were presented with spontaneous onset of colitis and subsequently tested positive on Salmonella quantitative polymerase chain reaction. All horses were >1 year of age and stratified by a dietary scale that included forages (pasture and hay) and concentrates grouped by percentage of fiber and amount. Methods: Illumina sequencing of 16S rRNA genes was performed on fecal DNA. Results: Healthy horses fed higher amounts of grain clustered separately from those fed lower amounts of grain (analysis of similarities [ANOSIM], R = 0.356‐0.385, Q = 0.002). Horses with AAD and Salmonella had decreased richness and evenness compared to healthy horses (P <.05). Univariable analysis of the 3 groups identified increases in Bacteroidetes (Q = 0.002) and Protebacteria (Q = 0.001) and decreases in Verrucomicrobia (Q = 0.001) in AAD horses whereas Salmonella horses had less Firmicutes (Q = 0.001) when compared to healthy horses. Conclusions and Clinical Importance: Although the amount of grain in the diet had some impact on the fecal microbiome, colitis had a significantly larger influence. Horses with ADD have a more severe dysbiosis than do horses with Salmonella. [ABSTRACT FROM AUTHOR]

Adult Pacific salmon Oncorhynchus spp. undertake energetically demanding migrations where they must have adequate energy reserves to survive to reach spawning locations and reproduce. Lethal proximate analysis provides insight into available energy stores (e.g., lipids), but the ability to monitor energetic status nonlethally may be useful for managers. Nonlethal monitoring may be more cost effective, reduce harm to sensitive populations, allow for more fish to be sampled, and assessments can be done relatively quickly. Chinook Salmon Oncorhynchus tshawytscha (N = 129) were sampled for proximate analysis from four populations in Alaska to examine variation in energetic status before and after spawning migration and to create predictive bioelectrical impedance analysis (BIA) models for this species. In addition to proximate analysis we tested the variability between two BIA devices (Q2 and CQR), whether BIA models were generalizable to a congener, Chum Salmon Oncorhynchus keta, and the feasibility of integrating BIA into field studies. The populations that were sampled at prespawning migration had higher %lipid (N = 77; mean = 43%) than those that were collected at postspawning migration (N = 52; mean = 20%). Total %lipid and %water was more accurately predicted based on BIA measurements that were made by using the Q2 device (RMSE = 5.33 and RMSE = 2.43, respectively) than on those that were made by using the CQR device measurements (RMSE = 6.27; RMSE = 2.66). The between‐species (Chinook Salmon to Chum Salmon RMSE = 19.47; Chum to Chinook RMSE = 7.69) models were less accurate than species‐specific models that were created for Chinook Salmon and Chum Salmon, suggesting that single‐species models should be used. We field‐tested the BIA model to predict %lipid and %water for Chinook Salmon on a remote Southeast Alaska river. The range of predicted values of %lipid and %water was similar to the results that are obtained via proximate composition from the other populations. Our results indicate that BIA could be a valuable tool for assessing the spatial and temporal patterns of energetic status for Chinook Salmon populations. [ABSTRACT FROM AUTHOR]

Two limitations have been discovered in the derivation of the Eulerian method of hemolysis prediction using a linearized blood damage function. First is that in the transformation from the Lagrangian material volume of the original power‐law model to a fixed Eulerian control volume, the spatial dependence of duration of exposure to fluid stress was neglected. This omission has the implication that the Eulerian method as reported is valid only for steady, uniaxial flow in which velocity is constant along streamlines. The second issue is related to linearization, which involves distributing an exponent across an integral. This operation is valid only for limited conditions that include the exponent being unity (which is not the case for any power‐law hemolysis models) or the blood damage function being constant throughout the flow regime. These constraints severely restrict the applicability of the Eulerian method. An example problem is presented that demonstrates that the source term of the Eulerian method as reported does not account for differences in velocity between 2 similar flows. Correcting the source term to match the hemolysis prediction to that of the original, unlinearized method requires an analytical description of the flow field that may not be easily obtained for the complex flows in some cardiovascular devices. [ABSTRACT FROM AUTHOR]

Particle image velocimetry (PIV) and an extended solution of Stokes' second problem were used to validate a computational fluid dynamics (CFD) model of flow in an orbiting dish. Velocity vector components throughout one complete orbit differed between CFD and PIV by less than 5%. Computational velocity magnitudes averaged over the interior 20% radius, the region where the analytical solution is most applicable, were 0.3% higher than the analytical values, while the experimental values in the same region were 2.4% higher. Velocity profiles in the center of the dish across normalized heights that most influence wall shear stress varied on average by ∼-0.00046 for the normalized radial component and by ∼0.0038 for the normalized tangential component compared to the analytical solution. These results represent the most comprehensive validation to date for computational models of the orbiting dish system. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4233-4242, 2017 [ABSTRACT FROM AUTHOR]

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The proliferation of saltcedar ( Tamarix spp.) along regulated rivers in the western United States has transformed riparian plant communities. It is commonly assumed that transpiration by these alien plants has led to large losses of water that would otherwise contribute to streamflow. Control of saltcedar, therefore, has been considered a viable strategy for conserving water and increasing streamflow in these regions. In an effort to better understand the linkage between transpiration by saltcedar and streamflow, we monitored transpiration, stream stage, and groundwater elevations within a saltcedar stand along the Pecos River during June 2004. Transpiration, as determined by sap flow measurements, exhibited a strong diel pattern; stream stage did not. Diel fluctuations in groundwater levels were observed, but only in one well, which was located in the center of the saltcedar stand. In that well, the correlation between maximal transpiration and minimal groundwater elevation was weak (R2 = 0.16). No effects of transpiration were detected in other wells within the saltcedar stand, nor in the stream stage. The primary reason, we believe, is that the saltcedar stand along this reach of the Pecos River has relatively low sapwood area and a limited spatial extent resulting in very low transpiration compared with the stream discharge. Our results are important because they provide a mechanistic explanation for the lack of increase in streamflow following large-scale control of invasive trees along semiarid rivers. [ABSTRACT FROM AUTHOR]

Background Macrolide-resistant isolates of Rhodococcus equi are emerging, prompting the search for clinically effective alternative antimicrobials. Hypothesis The proportion of foals with ultrasonographic evidence of pneumonia presumed to be caused by R. equi that had a successful outcome when administered gallium maltolate (GaM) PO would not be more than 10% inferior (ie, lower) than that of foals receiving standard treatment. Animals Fifty-four foals with subclinical pulmonary abscesses among 509 foals at 6 breeding farms in Kentucky. Methods Controlled, randomized, prospective noninferiority study. Foals with ultrasonographic lesions >1 cm in diameter (n = 54) were randomly allocated to receive per os either clarithromycin combined with rifampin ( CLR+R) or GaM, and followed up for 28 days by daily physical inspections and weekly (n = 1 farm) or biweekly (n = 4 farms) thoracic ultrasound examinations by individuals unaware of treatment-group assignments. Treatment success was defined as resolution of ultrasonographically identified pulmonary abscesses within 28 days of initiating treatment. Noninferiority was defined as a 90% confidence interval for the observed difference in CLR+R minus GaM that was ≤10%. Results The proportion of GaM-treated foals that resolved (70%; 14/20) was similar to that of foals treated with CLR+R (74%; 25/34), but we failed to demonstrate noninferiority for GaM relative to CLR+R; however, GaM was noninferior to CLR+R treatment when results from a noncompliant farm were excluded. Conclusions and Clinical Importance Gallium maltolate is not inferior to macrolides for treating foals with subclinical pneumonia. Use of GaM might reduce pressure for macrolide-resistance in R. equi. [ABSTRACT FROM AUTHOR]

Purpose To validate conventional phase-contrast MRI (PC-MRI) measurements of steady and pulsatile flows through stenotic phantoms with various degrees of narrowing at Reynolds numbers mimicking flows in the human iliac artery using stereoscopic particle image velocimetry (SPIV) as gold standard. Materials and Methods A series of detailed experiments are reported for validation of MR measurements of steady and pulsatile flows with SPIV and CFD on three different stenotic models with 50%, 74%, and 87% area occlusions at three sites: two diameters proximal to the stenosis, at the throat, and two diameters distal to the stenosis. Results Agreement between conventional spin-warp PC-MRI with Cartesian read-out and SPIV was demonstrated for both steady and pulsatile flows with mean Reynolds numbers of 130, 160, and 190 at the inlet by evaluating the linear regression between the two methods. The analysis revealed a correlation coefficient of > 0.99 and > 0.96 for steady and pulsatile flows, respectively. Additionally, it was found that the most accurate measures of flow by the sequence were at the throat of the stenosis (error < 5% for both steady and pulsatile mean flows). The flow rate error distal to the stenosis was primarily found to be a function of narrowing severity including dependence on proper Venc selection. Conclusion SPIV and CFD provide excellent approaches to in vitro validation of new or existing PC-MRI flow measurement techniques. J. Magn. Reson. Imaging 2014;39:1477-1485. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Hemolysis caused by flow in hypodermic needles interferes with a number of tests on blood samples drawn by venipuncture, including assays for metabolites, electrolytes, and enzymes, causes discomfort during dialysis sessions, and limits transfusion flow rates. To evaluate design modifications to address this problem, as well as hemolysis issues in other cardiovascular devices, computational fluid dynamics ( CFD)-based prediction of hemolysis has potential for reducing the time and expense for testing of prototypes. In this project, three CFD-integrated blood damage models were applied to flow-induced hemolysis in 16- G needles and compared with experimental results, which demonstrated that a modified needle with chamfered entrance increased hemolysis, while a rounded entrance decreased hemolysis, compared with a standard needle with sharp entrance. After CFD simulation of the steady-state velocity field, the time histories of scalar stress along a grid of streamlines were calculated. A strain-based cell membrane failure model and two empirical power-law blood damage models were used to predict hemolysis on each streamline. Total hemolysis was calculated by weighting the predicted hemolysis along each streamline by the flow rate along each streamline. The results showed that only the strain-based blood damage model correctly predicted increased hemolysis in the beveled needle and decreased hemolysis in the rounded needle, while the power-law models predicted the opposite trends. [ABSTRACT FROM AUTHOR]

BACKGROUND: Chikungunya virus (CHIKV) outbreaks were previously restricted to parts of Africa, Indian Ocean Islands, South Asia, and Southeast Asia. In 2007, however, the first autochthonous CHIKV trans-mission was reported in Europe. High-level viremia, a mosquito vector that is also present in large urban areas of Europe and America, and uncertainty around the resistance of this Alphavirus toward physiochemical inactivation processes raised concerns about the safety of plasma derivatives. To verify the safety margins of plasma products with respect to CHIKV, commonly used virus inactivation steps were investigated for their effectiveness to inactivate this newly emerging virus. STUDY DESIGN AND METHODS: Pasteurization for human serum albumin (HSA), vapor heating for Factor VIII inhibitor bypassing activity, solvent/detergent (S/D) treatment for intravenous immunoglobulin (IVIG), and incubation at low pH for IVIG were investigated for their capacity to inactivate CHIKV and the closely related Sindbis virus (SINV). The obtained results were com-pared to previous studies with West Nile virus and the commonly used model virus bovine viral diarrhea virus. RESULTS: The data generated demonstrate the effec-tive inactivation of CHIKV as well as SINV by the inacti-vation steps investigated and thereby support results from earlier validation studies in which model viruses were used. CONCLUSION: High inactivation capacities with respect to CHIKV were demonstrated. This provides solid reassurance for the safety of plasma products and the results verify that the use of model viruses is appro-priate to predict the inactivation characteristics of newly emerging viruses when their physicochemical properties are well characterized. [ABSTRACT FROM AUTHOR]

The invasive tree, Tamarix sp., was introduced to the United States in the 1800s to stabilize stream banks. The riparian ecosystem adjacent to the middle Rio Grande River in central New Mexico consists of mature cottonwood ( Populus fremontii) gallery forests with a dense Tamarix understory. We hypothesized that Populus would compensate for reduced competition by increasing its water consumption in restored riparian plots following selective Tamarix removal, resulting in similar transpiration ( T) among stands. The northern study site included a Populus stand invaded by Tamarix (INVN) and a restored Populus-only stand (RESN), as did a southern site (INVS and RESS) approximately 80 miles south. At each site, 20 × 20-m plots were established where up to 16 stems were monitored throughout the 2004 growing season using thermal dissipation sapflow sensors. Populus sapflux rates were greater in restored stands, suggesting those trees compensated for understory removal by using more water. Sapflow was scaled to estimate stand-level T based on a quantitative assessment of sapwood basal area ( Asw) by species. Although exotic species represented 85 and 91% of the total stems in the invaded stands, it amounted to only 3% (INVS) and 4% (INVN) of the total Asw, contributing proportionately less to T compared to Populus. Our results indicate that removing Tamarix from the Populus understory in this riparian forest had a minimal impact on stand water balance. Riparian restoration of the type discussed herein should focus primarily on enhancing riparian health rather than generating water. [ABSTRACT FROM AUTHOR]

Wall shear stress (WSS) on anchored cells affects their responses, including cell proliferation and morphology. In this study, the effects of the directionality of pulsatile WSS on endothelial cell proliferation and morphology were investigated for cells grown in a Petri dish orbiting on a shaker platform. Time and location dependent WSS was determined by computational fluid dynamics (CFD). At low orbital speed (50 rpm), WSS was shown to be uniform (0-1 dyne/cm2) across the bottom of the dish, while at higher orbital speed (100 and 150 rpm), WSS remained fairly uniform near the center and fluctuated significantly (0-9 dyne/cm2) near the side walls of the dish. Since WSS on the bottom of the dish is two-dimensional, a new directional oscillatory shear index (DOSI) was developed to quantify the directionality of oscillating shear. DOSI approached zero for biaxial oscillatory shear of equal magnitudes near the center and approached one for uniaxial pulsatile shear near the wall, where large tangential WSS dominated a much smaller radial component. Near the center (low DOSI), more, smaller and less elongated cells grew, whereas larger cells with greater elongation were observed in the more uniaxial oscillatory shear (high DOSI) near the periphery of the dish. Further, cells aligned with the direction of the largest component of shear but were randomly oriented in low magnitude biaxial shear. Statistical analyses of the individual and interacting effects of multiple factors (DOSI, shear magnitudes and orbital speeds) showed that DOSI significantly affected all the responses, indicating that directionality is an important determinant of cellular responses. Biotechnol. Bioeng. 2012; 109:695-707. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The starry sky hepatic pattern is an unusual ultrasonographic appearance of equine liver characterized by numerous small, hyperechoic foci, some of which cast an acoustic shadow, distributed randomly throughout the hepatic parenchyma. Our objectives were to describe the signalment, clinical signs, clinicopathological findings, primary disease process, and ultrasonographic findings of horses with this ultrasonographic pattern, as well as determine the associated gross and histologic changes. The starry sky pattern was identified in 18 adult horses of mixed gender and breed. The horses had various clinical signs, with weight loss and anorexia reported most commonly. Liver size and parenchymal echogenicity were normal in most horses. The hyperechoic foci frequently caused acoustic shadowing. Biliary dilation was noted rarely. The ultrasonographic pattern was the result of numerous fibrosing hepatic granulomas in all horses evaluated histologically. γ-Glutamyltransferase was the most commonly elevated hepatic enzyme, though it was increased in fewer than half the horses. Fifteen horses had an additional disease that was identified as the apparent cause of clinical signs. Three horses had primary hepatic disease while 12 had diseases of other body systems. Therefore, the starry sky ultrasonographic pattern is likely incidental in most horses and not clinically significant. Improved recognition of this pattern and further investigation of affected horses may help refine the etiology and clinical significance of the granulomas. [ABSTRACT FROM AUTHOR]

Eur J Clin Invest 2011; 41 (8): 807-819 Abstract Background Of the many possible factors that may contribute to orthostatic intolerance, the loss of circulating blood because of capillary filtration is one of the few that can explain the gradual decline of arterial pressure during stand tests. This study used a computer model to investigate the relative importance of haemodynamic parameters, including capillary filtration, as potential contributors to orthostatic intolerance. Simulated orthostatic tolerance times were compared to previous experiments combining head-up tilt and lower body negative pressure graded orthostatic stress, which provided haemodynamic data, in particular haematocrit measurements that allowed subject-specific modelling of capillary transport. Materials and methods The cardiovascular system was simulated using a seven-compartment model with measured heart rate, stroke volume, total peripheral resistance, mean arterial pressure and haematocrit data for 12 subjects. Simulations were controlled by decreasing the total blood volume at the measured rates of capillary filtration until cerebral pressure dropped below a threshold for consciousness. Predicted times to syncope were compared to actual times to presyncope, and sensitivity of arterial pressure and cardiac output to independent system parameters were determined. Results There was no statistical difference in modelled times to syncope and actual times to presyncope. Both arterial pressure and cardiac output were most sensitive to total blood volume and least sensitive to caudal compliance parameters. Conclusions The feasibility of subject-specific simulations of cardiovascular response to orthostatic stress was demonstrated, providing stronger evidence that capillary filtration is a prominent mechanism in causing orthostatic intolerance. These results may have clinical and spaceflight applications. [ABSTRACT FROM AUTHOR]

It is well documented that physiological and morphological properties of anchored cells are influenced by fluid shear stress. Common orbital shakers provide a means of simultaneously applying shear stress to cells for tens to hundreds of cases by loading the shaker with multiple dishes. However, the complex flow in orbiting dishes is amenable to analytical solution for resolving shear created by the fluid motion only for simplified conditions. The only existing quantification of shear in this flow is an equation that estimates a constant scalar value of shear for the entire surface of the dish. In practice, wall shear stress (WSS) will be oscillatory rather than steady due to the travelling waveform and will vary across the surface of the dish at any instant in time. This article presents a computational model that provides complete spatial and temporal resolution of WSS over the bottom surface of a dish throughout the orbital cycle. The model is reasonably well validated by the analytical solution, with resultant WSS magnitudes that are within 0.99 ± 0.42 dyne/cm. The model results were compared to tangential WSS magnitudes obtained using one-dimensional optical velocimetry at discreet locations on the bottom of an orbiting dish. The experimental minimum and maximum WSS at 1 mm from the center of the dish were 6 and 7 dyne/cm, respectively, whereas WSS generated from the computational model ranged from 0.5 to 8.5 dyne/cm. The experimental minimum and maximum WSS at 12 mm from the center of the dish were 6 and 16 dyne/cm, respectively, whereas WSS generated from the computational model ranged from 0.5 to 14 dyne/cm. Discrepancies between the experimental and computational data may be attributed to a sparse sampling rate for the experimental probe, a sharp gradient at the sample area which could cause the unidirectional probe to be inaccurate if its location were not precise, and too few particles to track and a scattering of the signal by the free surface when the liquid is shallow. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011 [ABSTRACT FROM AUTHOR]

Hemolysis is caused by fluid stresses in flows within hypodermic needles, blood pumps, artificial hearts, and other cardiovascular devices. Developers of cardiovascular devices may expend considerable time and effort in testing of prototypes, because there is currently insufficient understanding of how flow-induced cell damage occurs to accurately predict hemolysis. The objective of this project was to measure cell deformation in response to a range of flow conditions, and to develop a constitutive model correlating cell damage to fluid stresses. An experimental system was constructed to create Poiseuille flow under a microscope with velocities up to 4 m/s, Reynolds number to 200, and fluid stresses to 5000 dyn/cm. Pulsed laser illumination and a digital camera captured images of cells deformed by the flow. Equilibrium equations were developed to relate fluid stresses to cell membrane tension, and a viscoelastic membrane model was used to predict cell strain. Measurements of aspect ratio as a function of shear stress and duration of shear were used to calibrate the cell deformation model. Hemolysis prediction was incorporated with a threshold strain value for cell rupture. The new model provides an improved match to experimentally observed hemolytic stress thresholds, particularly at long exposure times, and may reduce the empiricism of hemolysis prediction. [ABSTRACT FROM AUTHOR]

A potential application for conductive resins is in bipolar plates for use in fuel cells. The addition of carbon filler can increase the electrical and thermal conductivities of the polymer matrix but will also have an effect on the tensile and flexural properties, important for bipolar plates. In this research, three different types of carbon carbon black, synthetic graphite, and carbon nanotubes were added to polypropylene and the effects of these single fillers on the flexural and tensile properties were measured. All three carbon fillers caused an increase in the tensile and flexural modulus of the composite. The ultimate tensile and flexural strengths decreased with the addition of carbon black and synthetic graphite, but increased for carbon nanotubespolypropylene composites due to the difference in the aspect ratio of this filler compared to carbon black and synthetic graphite. Finally, it was found that the Nielsen model gave the best prediction of the tensile modulus for the polypropylene based composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

The brook trout is an important species across North America, being the focus of restoration and conservation efforts in the eastern United States and considered a threat to native salmonids in the western part of the country. Bioenergetics models have emerged as useful tools for studying the ecology and management of fish species, but these models should be critically evaluated prior to widespread application. We conducted laboratory experiments to refine model parameters (metabolism and the activity multiplier) and to test a model for brook trout. Brook trout metabolic rates increased with temperature up to 20°C, then declined sharply. Specific metabolism declined with increasing fish size. Validation experiments conducted for 7, 21, and 31 d at 12-16°C showed that the model predicted consumption within 1.6 ± 3.6%, growth within 2.3 ± 12.5%, and final weight within 1.7 ± 5.1% of measured values. The results of this study will allow biologists to better use bioenergetics models to study the trophic dynamics of brook trout throughout their range. [ABSTRACT FROM AUTHOR]

Electrically conductive resins may have applications as fuel cell bipolar plates. The current trend in this technology is a thermosetting polymer as the matrix containing high concentrations of various types of fillers. These fillers are carbon based and electrically conductive powders, particles, or fibers. In this study, we utilized two composite formulations of polyacrylonitrile fibers (Fortafil 243 and Panex 30) in a liquid crystal polymer (Vectra A950RX) with increasing concentrations. Electrical conductivity tests were performed and modified Mamunya and additive models were applied to the experimental data. These models fit the entire range of data for each composite tested. Four alternate models were also produced: linear, quadratic, exponential, and geometric, with a restricted range of electrical conductivity data greater than 10−2 S/cm. The exponential and the geometric resulted in the best fits over this restricted data range. These particular models may allow researchers to extrapolate beyond the maximum filler concentrations studied here. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [ABSTRACT FROM AUTHOR]

There is an emerging market for conductive resins for use in fuel cell bipolar plates. This research focuses on developing a finite element model of a capillary rheometer. Comsol Multiphysics 3.2b was used to model the flow of a remeltable thermoplastic matrix material, Vectra A950RX Liquid Crystal Polymer, with varying amounts of either a carbon black or synthetic graphite filler, to obtain the velocity profile and pressure drop of these composites within the capillary. Previous experimental results have shown that the molten composites obey a shear‐thinning power law behavior. When comparing the model predicted pressure drops from the model with the experimental data, very good agreement was obtained. This signifies that the rheological behavior of the composites can be described by a power law relationship, using parameters specific to each composite. When comparing the modeled velocity profile with the theoretical profile, it was found for all composite formulations that the velocity becomes fully developed within a length of 0.05 times the diameter of the tube, independent of the power law parameters n and m. This work is a necessary first step in developing 2D or 3D mold filling simulations for fuel cell bipolar plate applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [ABSTRACT FROM AUTHOR]

Thermally conductive resins are needed for bipolar plates in fuel cells. Currently, the materials used for these bipolar plates often contain a single type of graphite in a thermosetting resin. In this study, varying amounts of four different types of polyacrylonitrile carbon fillers (Ketjenblack carbon black, Thermocarb synthetic graphite, Fortafil 243 carbon fiber, and Panex 30 carbon fiber) were added to a thermoplastic matrix (Vectra A950RX Liquid Crystal Polymer), with the resulting resins tested for through‐plane and in‐plane thermal conductivity. There are two unique contributions of this work. The first contribution is the use of the Nielsen model for the through‐plane thermal conductivity as a function of the single filler volume fraction. The model fits the data for all composites well. The second contribution is the development of a new, accurate, empirical model to predict the in‐plane thermal conductivity for all resins containing synthetic graphite or carbon fiber. Both of these models will form the basis for the development of new thermal conductivity models for composites with multiple fillers for fuel cell bipolar plate applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [ABSTRACT FROM AUTHOR]

In this paper, we examine the linkage between woody plants and the water budget for three important woody plant communities in Texas, USA: saltcedar (Tamarix chinensis, Tamarix ramosissima), Ashe juniper (Juniperus ashei Buchholz), and mesquite (Prosopis glandulosa Ton. var. glandulosa). In most cases, these species are found in distinct physiographic and soil settings. Saltcedar is restricted to stream channels and floodplains; Ashe juniper is found mostly on karst limestone outcrops with shallow soils; and mesquite is found on deep soils. Because of these differences, changes in woody plant cover in each community will have a different effect on the water budget. For each type, we review the available literature and explicitly report the scale of observation (tree, stand, catchment, or landscape). A simple framework called the shrub-streamfiow framework, which recognizes differences in response due to differences in physiographic setting, climate, and potential for deep drainage or subsurface flow, enables us to generalize the results. The fundamental premise of the framework is simple: for shrublands to be hydrologically sensitive to changes in woody plant cover, soil water or groundwater must be accessible to deep-rooting plants but too deep for shallow-rooting ones. Such a situation exists if groundwater is close to the surface (within 3–5 m and/or if deep drainage occurs (because of either high precipitation input or bypass flow in the soil). We argue that on an area basis, conversion of saltcedar stands to herbaceous plants in riparian regions has a much greater potential for increasing water yield than does conversion of woodlands to grasslands in upland regions where deep drainage does not occur. On upland sites where deep drainage does occur, conversion from woody to herbaceous vegetation may result in a savings of 40–80 mm year-1 of water. But such savings have been observed only up to the small-catchment scale, and until further work is done it is uncertain whether they can be achieved at larger scales. [ABSTRACT FROM AUTHOR]

Partitioning bulk rainfall into canopy interception, litter interception, stemfiow and throughfall allows an estimate of the physical impact of trees on the local hydrologic budget. Despite recognition of the potentially large effect of interception and associated processes on the hydrologic budget, few, if any, studies have quantitatively evaluated the multiple components simultaneously in semiarid savannas, nor have the effects of rainfall intensity within storms been rigorously evaluated. We monitored interception and rainfall partitioning in individual Ashe juniper (Juniperus ashei Buchholz) canopies at ten sites over a 3-year period. Averaged over all ten sites for 2700 total rain events, about 35% of the bulk rainfall falling on juniper trees was intercepted by the tree canopy, 5% was intercepted by the coarse litter and duff beneath the tree, 55% reached the ground surface as direct and released throughfall, and 5% was redirected to the base of the tree as stemflow. Small amounts of rainfall (<2.5 mm) were entirely captured by the canopy and evaporated to the atmosphere, contributing nothing to soil water under juniper trees. Low intensity rainfall (e.g. 13 mm over a 19-h period) that could conceivably benefit the local plant community was largely intercepted by the tree canopy (>60% interception). High intensity rainfall was less influenced by juniper canopies. At high intensities (e.g. >70 mm over a 15-h period) only 20% of the bulk precipitation was intercepted by the canopy and litter. The hourly pattern of rainfall within extended storms demonstrated periods with low intensity and periods with high intensity. The interception rates during these periods closely mimic the rates seen in similar intensity short duration storms. Canopy and litter interception effectively reduced the beneath-canopy precipitation from 600 to 360 mm in the western region and from 900 to 540 mm in the eastern region. [ABSTRACT FROM AUTHOR]

The article presents a study of woody plants and their possible effect on streamflow of semiarid karst rangelands. It highlights the impact of human population growth on the ecosystems and water supply leading the significance of comprehending the link between the plants and water yield in drylands. An overview of ecohydrology and analysis of runoff is also presented.

A retrospective study of 25 patients with severe soft tissue injuries to the perineum from the last 14 years was performed to determine the most appropriate management strategy for these problematic wounds. There were 20 (80%) men and 5 (20%) women with an average age of 29 years. Six (24%) patients died of exsanguination from their pelvic injuries within the first few hours of presentation. The remaining 19 patients were taken to the operating room for sigmoidoscopy, diverting colostomy, distal rectal washout, and radical debridement and irrigation of any devitalized tissue. Enteral access by jejunostomy was obtained in six patients. Most patients underwent daily debridement and pulsatile irrigation for at least three days, but usually longer, until the treating surgeon deemed the wound to be clean. None of the patients managed in this fashion developed pelvic sepsis. However, pelvic sepsis did occur in all four patients who did not receive early mandatory daily debridement. Total parenteral nutrition was required in eight patients because there were significant delays in the ability of these patients to resume oral intake. In most previously published series in which daily debridement was not performed, a pelvic sepsis rate of 40% to 80% was reported. Therefore, to optimize the clinical course and recovery from these complex wounds, we conclude that mandatory daily debridement with pulsatile irrigation should be instituted in conjunction with sigmoidoscopy, diversion of the fecal stream, distal rectal irrigation, enteral access, and initial radical debridement of devitalized tissue. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined the tooth replacement and wear in aging white-tailed deer in south-central Oklahoma. Methodology; Results and discussion; Conclusions.

Probabilistic knowledge is an important input to the analysis of many decisions, and may be required for long-range forecasting, classical decision analysis, influence diagrams, fault tree analysis, and expert systems. If objective probabilities cannot be calculated, it is vital that decision makers use the best available subjective measures of probability. Standard mathematical theory allows the analyst several choices in framing subjective probability assessments. When assessing cause-effect probabilities, the three choices are causal, diagnostic, and joint probabilities. Choosing among these is difficult in light of conflicting reports that, due to cognitive heuristics, probability judgment may be biased in various poorly understood ways. For example, it has been reported that, when judging causal probabilities, people are subject to the causal information bias, and thus upwardly revise their prior probabilities more than when judging diagnostic probabilities. On the other hand, it has also been reported that in some cases, people do not take proper account of new evidence, which results in under-revision of prior probabilities. Furthermore it has been reported that, when assessing joint probabilities, people are subject to the conjunction fallacy, and thus often judge a joint probability to be higher than one of the two corresponding marginal probabilities. Our research compares the relative effects of these biases in a laboratory setting: we present new empirical results comparing the test-retest reliabilities and under(over) revision rates of causal, diagnostic, and joint probabilities. Our results suggest that the tendency to both under-revise and over-revise prior probabilities is greatest when judging diagnostic probabilities, as opposed to either causal or joint probabilities. Furthermore our results suggest that joint probability judgment is more reliable than either causal or diagnostic probability judgment [ABSTRACT FROM AUTHOR]

Mature canoia (Brassica napus cv. Westar) seeds contain large quantities of the storage proteins cruciferin and napin and storage lipids rich in C18:1 and C18:2 fatty acids. Both the quantity and quality of these products are altered by freezing during development. Further, the response to freezing changes during seed development. The effects include decreased fatty acid chain elongation, altered fatty acid unsaturation, higher lipid levels and lower protein levels. In addition, seeds in the pivotal moisture range (55%) may be predisposed to precocious germination, which is then inhibited by a lack of adequate seed moisture. The results indicate that freezing imparts its effect in two ways. Initially, there is a freezing (low temperature) component and this is followed by rapid desiccation of the seeds. Although most responses probably result from a combination of the stresses, it appears that inhibition of fatty acid chain elongation is caused by the freezing component and the gradual inhibition of storage protein accumulation is a result of accelerated seed desiccation. [ABSTRACT FROM AUTHOR]

Focuses on the cost efficiency of forage plantings for white-tailed deers in the United States. Important factor for the timing of forage production; Average annual cost of establishing and maintaining individual forages.