cssi/SciSciGPT-SciSciNet huggingface dataset:
Fuel Cells: Proton Exchange Membranes

Proton exchange membrane, also known as polymer electrolyte membrane, fuel cells (PEMFCs) offer the promise of efficient conversion of chemical energy of fuel, such as hydrogen or methanol, into electricity with minimal pollution. Their widespread use to power zero-emission automobiles as part of a hydrogen economy can contribute to enhanced energy security and reduction in greenhouse gas emissions. However, the commercial viability of PEMFC technology is hindered by high cost associated with the membrane-electrode assembly (MEA) and poor membrane durability under prolonged operation at elevated temperature. Membranes for automotive fuel cell applications need to perform well over a period comparable to the life of an automotive engine and under heavy load cycling including start-stop cycling under subfreezing conditions. The combination of elevated temperature, changes in humidity levels, physical stresses, and harsh chemical environment contribute to membrane degradation. Perfluorinated sulfonic acid (PFSA)-based membranes, such as Nafion®, have been the mainstay of PEMFC technology. Their limitations, in terms of cost and poor conductivity at low hydration, have led to continuing research into membranes that have good proton conductivity at elevated temperatures above 120 °C and under low-humidity conditions. Such membranes have the potential to avoid catalyst poisoning, simplify fuel cell design, and reduce the cost of fuel cells. Hydrocarbon-based membranes are being developed as alternatives to PFSA membranes, but concerns about chemical and mechanical stability and durability remain. Novel anhydrous membranes based on polymer gels infused with protic ionic liquids have also been recently proposed, but considerable fundamental research is needed to understand proton transport in novel membranes and evaluate durability under fuel cell operating conditions. In order to advance this promising technology, it is essential to rationally design the next generation of PEMs on the basis of an understanding of chemistry, membrane morphology, and proton transport obtained from experiment, theory, and computer simulation. Keywords: fuel cells; proton exchange membrane; polymer membrane; ionic liquid; energy efficiency; energy conversion; hydrogen economy; pollution prevention; proton transport
Caffeine and 3-km cycling performance: Effects of mouth rinsing, genotype, and time of day.

We assessed the efficacy of caffeine mouth rinsing on 3-km cycling performance and determined whether caffeine mouth rinsing affects performance gains influenced by the CYP1A2 polymorphism. Thirty-eight recreational cyclists completed four simulated 3-km time trials (TT). Subjects ingested either 6 mg/kg BW of caffeine or placebo 1 h prior to each TT. Additionally, 25 mL of 1.14% caffeine or placebo solution were mouth rinsed before each TT. The treatments were Placebo, caffeine Ingestion, caffeine Rinse and Ingestion+Rinse. Subjects were genotyped and classified as AA homozygotes or AC heterozygotes for the rs762551 polymorphism of the CYP1A2 gene involved in caffeine metabolism. Magnitude-based inferences were used to evaluate treatment differences in mean power output based on a predetermined meaningful treatment effect of 1.0%. AC heterozygotes (4.1%) and AA homozygotes (3.4%) benefited from Ingestion+Rinse, but only AC performed better with Ingestion (6.0%). Additionally, Rinse and Ingestion+Rinse elicited better performance relative to Placebo among subjects that performed prior to 10:00 h (Early) compared with after 10:00 h (Late). The present study provides additional evidence of genotype and time of day factors that affect the ergogenic value of caffeine intake that may allow for more personalized caffeine intake strategies to maximize performance.
Performance characterization of data-intensive kernels on AMD Fusion architectures

The cost of data movement over the PCI Express bus is one of the biggest performance bottlenecks for accelerating data-intensive applications on traditional discrete GPU architectures. To address this bottleneck, AMD Fusion introduces a fused architecture that tightly integrates the CPU and GPU onto the same die and connects them with a high-speed, on-chip, memory controller. This novel architecture incorporates shared memory between the CPU and GPU, thus enabling several techniques for inter-device data transfer that are not available on discrete architectures. For instance, a kernel running on the GPU can now directly access a CPU-resident memory buffer and vice versa. In this paper, we seek to understand the implications of the fused architecture on CPU-GPU heterogeneous computing by systematically characterizing various memory-access techniques instantiated with diverse memory-bound kernels on the latest AMD Fusion system (i.e., Llano A8-3850). Our study reveals that the fused architecture is very promising for accelerating data-intensive applications on heterogeneous platforms in support of supercomputing.
STRUCTURE OF THE VASCULAR PARENCHYMA IN THE STEM OF LYCOPODIUM LUCIDULUM

At maturity the vascular cylinder of the stem of Lycopodium lucidulum contains two distinct types of parenchyma cells, one which is always associated with sieve cells, the other with tracheids. The remaining parenchyma cells have characteristics intermediate between the two extremes. The most conspicuous feature of the sieve cell-associated parenchyma cell is the very dense appearance of its protoplast, due to a high ribosome population and absence of large vacuoles. The large, ramifying nuclei of these cells have numerous connections with the endoplasmic reticulum (ER). The tracheid-associated parenchyma cells, which are light in appearance, contain many small vacuoles and a relatively small ribosome population. These cells also contain relatively small nuclei and considerable ER cisternae. The parenchymatous elements which have characteristics intermediate between sieve celland tracheid-associated parenchyma may or may not be contiguous to the sieve cells or tracheids. An intergradation in wall thickness occurs among parenchyma cells of the vascular cylinder, the thicker-walled cells being adjacent to the sieve cells, the thinner-walled ones next to the tracheids. An intergradation also occurs in the frequency of plasmodesmata between the various parenchyma cells. The closer parenchyma cells are to the sieve cells the greater the number of connections between them. No plasmodesmata were found between the tracheid-associated parenchyma cells.
The Importance of Autonomy in Encouraging Creativity: Managerial Implications from a Study in Fashion Design

Dimensions of autonomy that organizations might consider in initiatives in enhancing creative task performance on an artistic task were examined. Choice of problem and leeway in timing had significant effects on creative performance. The results have strategic implications for managing creativity.
An assessment of the accuracy of a regional economic-demographic projection model.

The purpose in this discussion is to briefly describe and to evaluate the accuracy of the demographic component of 1 regional economic demographic modeling system consisting of 2 structurally similar models. The RED 2 and TAMS models share a common structure represent economic demographic models and are among the most widely used. The accuracy of the models projections are determined by comparing their projections for 106 counties and 553 incorporated places in Texas and North Dakota to 1980 census counts and to projections from widely used alternative models for the counties of interest. The model consists of 6 major modules: economic demographic economic-demographic interface allocation public service and fiscal. The economic module uses a regional input output model to project income gross business volume by sector and by dividing gross business volume by productivity (per worker) employment demands. A cohort survival model is used to project population by age and sex and by the application of projected levels of labor force availability to population by age and sex labor supplies. The interface module links the economic and demographic modules by matching labor demand and supply to determine the migration of labor and applies projected family characteristics for workers to determine in-migrating or out-migrating population. The allocation module uses projected share and gravity allocation techniques to distribute population to incorporated places and counties within the region. On the basis of projected economic and demographic change population based and per capita rates are used to project public service demands and fiscal effects for all areas. The projection of final demand for both historical trends and for specific industrial changes allows the model to be used for baseline and impact projections. Assessment of the accuracy of the models indicates that they provided moderately accurate projections for counties and places in 1980 but reflected biases common to small area projections being least accurate for the smallest and most rapidly growing areas. The results indicated that they were as accurate as the projections from more purely demographic alternative models that had been widely used in the 2 states. Overall the analysis suggests that economic demographic models may merit more attention by demographic analysis and additional analysis of the accuracy of the economic public service fiscal and other projections from such models must be completed.
Racial differences in abdominal depot–specific adiposity in white and African American adults

BACKGROUND There is increasing interest in understanding racial differences in adiposity in specific body depots as a way to explain differential health risks associated with obesity. OBJECTIVE Our aim was to examine the differences in abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) between white and African American adults. DESIGN The sample included 1967 adults aged 18-84 y, including 790 white women, 435 African American women, 606 white men, and 136 African American men. Total body fat was measured by using dual-energy X-ray absorptiometry, whereas abdominal VAT and SAT cross-sectional areas (L4-L5 level) were measured by using computed tomography. Sex-specific differences in SAT and VAT between racial groups were analyzed by the use of general linear models, which controlled for age and total body fat. Additional models tested for racial differences in VAT and SAT and controlled for age, total body fat, smoking, and menopausal status. Statistical significance was accepted at P < 0.05. RESULTS Abdominal VAT was significantly higher in white than in African American men and women, even after adjustment for covariates. White women had significantly lower SAT than did African American women, both before and after adjustment for covariates. White men had significantly higher SAT than did African American men, but after adjustment for covariates, their SAT was lower than that of African American men. CONCLUSIONS Abdominal visceral adiposity is significantly greater in white men and women. After adjustment for covariates, white men and women had significantly lower SAT than did African American men and women. The results of this study highlight the heterogeneity of human body fat distribution across racial groups.This trial was registered at clinicaltrials.gov as NCT00959270.
Prediction of van der waals interactions between plastics in water using the Lifshitz theory

Abstract According to the rigorous theory of Lifshitz, the old concept of a characteristic Hamaker Constant, used in the classical theory of van der Waals interactions between macroscopic bodies must be replaced by that of a Hamaker Function of the separation distance. This is evident from computations of interactions between slabs of plastics across water. The requisite dielectric polarizabilities of four plastics—polystyrene, polypropylene, polyethylene, and polytetrafluoroethylene—have been modeled using tabulated static dielectric constants, indices of refraction, absorption spectra, and ionization potentials. In the limit of large separations (⪆ 10,000 A), the Hamaker function goes to 3.2 × 10 −14 erg for all four plastics; in the opposite limit, as separations approach zero, H.F. values range from 9 × 10 −14 erg for polystyrene to 3.6 × 10 −14 erg for polytetrafluoroethylene. Furthermore, the Hamaker functions defined as coefficients of force vs those defined as coefficients of energy can differ by 13% for the materials examined here.
Role of subdermal current shunts in the failure of frogs to regenerate

Large, uniform, skin-driven currents (20-40 muamp/cm2) leave the ends of limb stumps of post-metamorphic frogs (Rana pipiens) from about the first through the tenth day after amputation. However, right after amputation, while currents of comparable density may leave the periphery of the cut surface, current densities are greatly depressed in the center of this surface. We suggest that this depression is brought about by shunting through the subdermal lymph space (characteristic of anurans but not urodeles); continues in covert form after formation of a wound epithelium; and helps explain the ability of small, imposed currents to initiate frog limb regeneration.
Tura´n theorems with repeated degrees

Abstract The maximum number of edges in a graph with no constant degree clique of a fixed size is determined asymptotically.
Rheology of synthetic latex VII. Flow behavior of synthetic rubber latex at low shear stress

Abstract The flow properties of low temperature GR-S X-667 latex have been investigated in a new low shear stress viscometer at 30.0°C. The range of shear stresses covered was 0.08 to 20.0 dynes/cm.2. The concentration was varied from 5% to 59% solids in approximately 5% increments. The latex was found to be completely Newtonian below a volume fraction of v = 0.246. Above v = 0.246 the latex flow was Newtonian at low shear stresses, changing to non-Newtonian as Fm was increased. Furthermore, the range of Fm over which the flow was Newtonian proved to be a linear function of the concentration between v = 0.320 and v = 0.544. Above 0.544 the flow behavior was non-Newtonian over the entire range of Fm covered in this study. It was found possible to express the flow behavior of this latex as a function of Fm and v in terms of the modified Eilers equation involving two parameters α and β; α was found to be a constant, while β was a function of Fm. This equation predicts that at infinite dilution 2α should equal the Einstein 2.50 for suspensions of spheres. When the observed values of 2α were corrected for the volume occupied by the layer of adsorbed soap on the latex particles, the value obtained for this factor was 2.52 ± 0.01. Again β, which is the volume fraction at which the viscosity becomes infinite, was found at the lower shear stresses to be of an order of magnitude expected for spheres with a mixture of orthorhombic and tetragonal packing. With increasing Fm the packing became tighter, and appeared to approach the densest, or rhombohedral, packing. The equation was used also to obtain an expression for the deviation of the latex from Newtonian behavior as a function of Fm and v. At any given shear stress the deviation was the greater the higher the volume fraction. Again, at volume fractions above v = 0.246, and below v = 0.544 the degree of non-Newtonian behavior decreased regularly with decrease in Fm, reaching a Newtonian limit at some low shear stress. However, no Newtonian limit was found above v = 0.544.
Discordance of oral-facial-digital syndrome type 1 in monozygotic twin girls

The oral-facial-digital syndrome type 1 (OFD1) includes limb, facial, intraoral malformations and the gene for the disorder was recently mapped to Xp22.3-p22.2. We report on monozygotic twin girls discordant for OFD1. Monozygosity is supported by placental pathology (monochorionic diamniotic) and molecular studies with probability of dizygosity <1 x 10(-6). The affected twin has oral cavity abnormalities including median cleft lip, cleft palate, lobulated hamartomatous tongue, aberrant hyperplastic oral frenula, alveolar notches, and absent lateral incisors. Facial manifestations include telecanthus, hypoplastic alae nasi, and transient neonatal facial milia. The patient also has short and deviated fingers with partial cutaneous syndactyly. At 10 years, she has not had central nervous system or kidney problems. X-inactivation study revealed similar X-inactivation patterns in the lymphoblasts of both twins. We conclude that skewed X-inactivation is an unlikely cause for the discordance, which is more likely due to a postzygotic mutation in the affected twin.
Coordinating with each other in a material world

In everyday joint activities, people coordinate with each other by means not only of linguistic signals, but also of material signals – signals in which they indicate things by deploying material objects, locations, or actions around them. Material signals fall into two main classes: directing-to and placing-for. In directing-to, people request addressees to direct their attention to objects, events, or themselves. In placing-for, people place objects, actions, or themselves in special sites for addressees to interpret. Both classes have many subtypes. Features of material signals were examined in pairs of people who were videotaped as they assembled TV stands, built Lego models, planned furnishings for a house, played piano duets, or bought coffee at Starbucks. In these activities, the pointing and placements were often sustained, creating three phases of signals – initiation, maintenance, and termination – each with its own interpretation.
RESEARCH: Perceptions of Risk Associated with Use of Farm Chemicals: Implications for Conservation Initiatives

/ Data were collected from 245 farmers within the Darby Creek hydrologic unit in central Ohio to assess perceptions of risk associated with use of farm chemicals. Farmers were asked to evaluate the level of risk associated with use of agricultural chemicals for water quality, food safety, food quality, health of applicator, health of farm animals, wildlife, beneficial plants, beneficial insects, and human health. Study findings revealed that respondents perceived use of farm chemicals posed little or no threat to any of the assessed items. A composite index was formulated from the responses to the nine items and was titled Perceived Risk. Variance in the Perceived Risk index was regressed against social learning variables. The findings revealed that approximately 32% of the variance was explained by the predictive variables included in the model. It was concluded that the theoretical perspective was somewhat useful for understanding perceptions held about agricultural chemical use at the farm level. The findings are discussed in the context of future conservation and educational-information programs within the study region.KEY WORDS: Risk perception; Risk assessment; Groundwater; Pesticide contamination; Food safety; Environmental quality Language: en
Test and Evaluation Procedures for the GPS User Equipment

Three Major Contractors, Collins Avionics and Missiles Division of Rockwell International, Magnavox, and Texas Instruments are currently involved in the development of a number of GPS user equipments. These will be flight tested to obtain a comprehensive evaluation of the GPS concept in the first phase of the program. However, prior to flight testing, a complete performance evaluation of these systems in the laboratory has been planned and for some systems, it is already in progress. To accomplish this objective, a number of SV signal generators and simulators have been designed and built, either under contract from the various administrative agencies or by the user equipment developers with private funding. These signal simulator systems provide a precise simulation of the satellite signals as received by the user equipment at its antenna. The effects of user vehicle dynamics, satellite motion and the atmospheric anomalies are precisely simulated. In the case of testing the high performance user equipment like the Generalized Development Model (GDM) system, the signal simulator also provides simulation of other auxiliary subsystems such as the INS system of the user vehicle. This paper describes the requirements and procedures employed in the pre-flight laboratory testing of the various user systems.
Analysis and Numerical Evaluation of the Drift Function of Darwin and Lighthill for Axisymmetric Flows

Darwin and Lighthill have studied the deformation or drift of material surfaces produced in the course of steady irrotational flows past cylinders and spheres. This paper is devoted to a reconsideration of the same problem for axisymmetric inviscid flows produced by arbitrary shaped bodies. Such problems cannot be solved by analytical techniques and, therefore, a recently developed algorithm has been brought into consideration to obtain the drift function numerically. First, the case of a sphere is considered to check and compare with the results obtained by Lighthill. Second, the developed algorithm has been used to obtain the drift functions in chosen patches of the stream surfaces produced by a prolate ellipsoid.
Racial bias in prediction with the MMPI for a juvenile delinquent population

Relationships between MMPI scales and criteria were evaluated to determine if the MMPI is racially biased with a juvenile delinquent population. The MMPI was administered to 333 white and 107 black male juvenile delinquents, and criterion data were collected. The regression equations developed for Blacks and whites resulted in similar accuracies. However, the weights of the regression equations tended to differ for the two races. How they differed depended on the criterion predicted by the equations. Consequently, it was impossible to state unconditionally that the use of the MMPI with Black delinquents will have an adverse impact. In fact, one interpretation of the results suggested that the MMPI may not be racially biased for predictions with juvenile delinquents because the amount of constant error in prediction for a racial group decreased toward zero as the apparent objectivity of the criteria increased.
Sound from Apollo Rockets in Space

Low-frequency sound has been recorded on at least two occasions in Bermuda with the passage of Apollo rocket vehicles 188 kilometers aloft. The signals, which are reminiscent of N-waves from sonic booms, are (i) horizontally coherent; (ii) have extremely high (supersonic) trace velocities across the tripartite arrays; (iii) have nearly identical appearance and frequencies; (iv) have essentially identical arrival times after rocket launch; and (v) are the only coherent signals recorded over many hours. These observations seem to establish that the recorded sound comes from the rockets at high elevation. Despite this high elevation, the values of surface pressure appear to be explainable on the basis of a combination of a kinetic theory approach to shock formation in rarefied atmospheres with established gas-dynamics shock theory.
A Random Forest Model Based on Lidar and Field Measurements for Parameterizing Surface Roughness in Coastal Modeling

A novel technique for parameterizing surface roughness in coastal inundation models using airborne laser scanning (lidar) data is presented. Two important parameters to coastal overland flow dynamics, Manning’s ${\bm {n}}$ (bottom friction) and effective aerodynamic roughness length (wind speed reduction), are computed based on a random forest (RM) regression model trained using field measurements from 24 sites in Florida fused with georegistered lidar point cloud data. The lidar point cloud for each test site is separated into ground and nonground classes and the z-dimensional (height or elevation) variance from the least squares regression plane is computed, along with the height of the nonground regression plane. These statistics serve as the predictor variables in the parameterization model. The model is then tested using a bootstrap subsampling procedure consisting of removal without replacement of one record and using the surviving records to train the model and predict the surface roughness parameter of the removed record. When compared with the industry standard technique of assigning surface roughness parameters based on published land use/land cover type, the RM regression models reduce the parameterization error by 93% (0.086–0.006) and 53% (1.299–0.610 m) for Manning’s ${\bm {n}}$ and effective aerodynamic roughness length, respectively. These improvements will improve water level and velocity predictions in coastal models.
Testicular effects on food intake, body weight, and body composition in male hamsters

Abstract Castration significantly increased body weight gain in male hamsters. Treatment with testosterone propionate (TP), 5α-dihydrotestosterone propionate (DHTP), or estradiol benzoate (EB) prevented the castration-induced weight gains. All of these body weight changes were seen in the absence of significant changes in food intake, suggesting an important role for metabolic actions of testicular steriods. Castration increased carcass lipid content and decreased protein content. Both of these effects were prevented by TP treatment. DHTP treatment prevented only the decrease in carcass protein, and EB treatment prevented only the increase in carcass lipid. The adiposity-reducing action of testosterone may be mediated by aromatized (estrogenic) metabolites, and 5α-reduced metabolites could have some anabolic effects. There was a highly-significant negative correlation between carcass lipid content and epididymal fat pad lipoprotein lipase activity, raising the possibility that in male hamsters testicular effects on adiposity may not be mediated via changes in lipoprotein lipase activity. Some other possible metabolic effects of testicular hormones are considered.
Initial mechanisms for the decomposition of electronically excited energetic materials: 1,5'-BT, 5,5'-BT, and AzTT.

Decomposition of nitrogen-rich energetic materials 1,5′-BT, 5,5′-BT, and AzTT (1,5′-Bistetrazole, 5,5′-Bistetrazole, and 5-(5-azido-(1 or 4)H-1,2,4-triazol-3-yl)tetrazole, respectively), following electronic state excitation, is investigated both experimentally and theoretically. The N2 molecule is observed as an initial decomposition product from the three materials, subsequent to UV excitation, with a cold rotational temperature (<30 K). Initial decomposition mechanisms for these three electronically excited materials are explored at the complete active space self-consistent field (CASSCF) level. Potential energy surface calculations at the CASSCF(12,8)/6-31G(d) level illustrate that conical intersections play an essential role in the decomposition mechanism. Electronically excited S1 molecules can non-adiabatically relax to their ground electronic states through (S1/S0)CI conical intersections. 1,5′-BT and 5,5′-BT materials have several (S1/S0)CI conical intersections between S1 and S0 states, related to different tetrazole ring opening positions, all of which lead to N2 product formation. The N2 product for AzTT is formed primarily by N–N bond rupture of the –N3 group. The observed rotational energy distributions for the N2 products are consistent with the final structures of the respective transition states for each molecule on its S0 potential energy surface. The theoretically derived vibrational temperature of the N2 product is high, which is similar to that found for energetic salts and molecules studied previously.
The Tryptophan Bridge Is a Critical Feature of the Papillomavirus E2 DNA Binding Domain

Abstract The papillomavirus E2 protein is a DNA binding protein that regulates viral transcription and replication. E2 binds DNA as a dimer. Recent crystallographic data for E2 complexed to DNA revealed that novel peptide structures in E2 mediated dimerization and DNA binding. To identify important features of these motifs we have used limited proteolysis and urea denaturation as biochemical probes for structure, applying these techniques to E2 alone, E2 bound to DNA, cross-linked products, and mutants that were targeted at Trp360, a contact point along the dimer interface. DNA binding stabilized E2 structure, shifting the point at which it denatures from 5 to 7.6 M urea. In contrast, Trp360 mutant proteins, while dimeric, were more sensitive to denaturation by urea when bound to DNA. The most striking results came from uv cross-linking studies in which Trp360 was targeted as the site of cross-linking. Ultraviolet cross-linking dramatically increased the resistance of E2 to proteolysis regardless of the protease tested and with no deleterious effect on the affinity of E2 for DNA. Cross-linking through Cys356 with bismaleimidohexane did not promote stabilization. The ability to stabilize or destabilize E2 by Trp360-targeted modifications demonstrates the importance of the Trp360-Trp360 interaction, which may represent a general feature of the β-barrel motif.
Calculating the Ecosystem Service of Water Storage in Isolated Wetlands using LiDAR in North Central Florida, USA

We used remotely-sensed Light Detection and Ranging (LiDAR) data to estimate potential water storage capacity of isolated wetlands in north central Florida. Data were used to calculate the water storage potential of >8500 polygons identified as isolated wetlands. We found that isolated wetlands in this area stored 1619 m3/ha on average, with a median measure of 876 m3/ha. Significant differences in average storage capacity were found depending on wetland type, ranging from 1283 m3/ha in palustrine scrub-shrub wetlands to 2906 m3/ha in palustrine aquatic bed wetlands. Our study tested LiDAR-derived volume measures and volumes calculated using currently available equations in landscapes with differing surficial geology formations (e.g., clayey sand, limestone) and found that accuracy improved when basin morphology, a function of near-surface geology, was included. An exponential equation was developed that accurately correlated isolated wetland area and volume in our study area, but overestimated volume by an average of 45% when tested with a small independent dataset from the same ecoregion. Results from this study can be used in hydrologic modeling at the landscape scale to estimate ecosystem services and may prove useful in determining the significant nexus between isolated wetlands and navigable waters.
Referrals to Allergists

Excerpt To the editor: As a primary care internist, I object to the tone and language of the editorial by Patterson and Fink (1), in which they tell us which patients we are "required" to refer to ...
Rubberlike materials, their internal damping and role in vibration isolation

Abstract The manner in which the internal damping and the dynamic elastic moduli of rubberlike materials depend upon frequency and temperature is described in detail. Examples are presented of the frequency dependence of the dynamic shear modulus and shear damping factor of low- and high-damping rubbers in the range 1 c/s through 10 kc/s at the temperatures 5, 2o and 35° C. These results have been deduced by the method of reduced variables from the experimental data of other workers. They relate to the low-damping materials natural rubber, natural rubber reinforced with carbon black, and SBR rubber; and to the high-damping materials Thiokol RD rubber, butyl rubber reinforced with carbon black, and plasticized polyvinyl acetate. The principles of vibration isolation are reviewed briefly. A simple general equation is derived from which the transmissibility any rubberlike material may be estimated, provided the frequency dependence of the dynamic shear modulus and the associated damping factor of the material are known. From this equation, the desirable physical characteristics of an effective vibration isolator are readily made apparent. Representative computations made from the general transmissibility equation are described; these computations incorporate numerical data that have been presented graphically for several of the foregoing low- and high-damping rubbers. The possible influence upon the transmissibility curves of nonlinear rubberlike behavior is discussed briefly. Detailed consideration is given to so-called wave effects that may occur at high frequencies, when the dimensions of the vibration isolator become comparable with multiples of the half-wavelength of the elastic wave traveling through the component rubberlike material. Thus, computations of transmissibility have been made from an expression derived with the assumption that the rubberlike materials obey the wave equation for the longitudinal vibration of a “long” rod of uniform cross-section. The results of these computations, which relate to the same rubbers as considered previously, are compared with the results obtained from the simple transmissibility equation. In the case of high-damping rubbers, the simple and more complex theories are found to be in good agreement. In the case of rubbers with relatively small damping, the effectiveness of the isolators at high frequencies is overestimated by the simple theory although, at these frequencies, the transmissibility of the isolators will normally remain a small quantity.
Inhibition of Three Pathogens on Bologna and Summer Sausage Using Antimicrobial Edible Films

Whey protein isolate (WPI) films (pH 5.2) containing 0.5 to 1.0% p-aminobenzoic acid (PABA) and/or sorbic acid (SA) were assessed for antimicrobial and mechanical properties while in contact with sliced bologna and summer sausage that were inoculated with Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica subsp. enterica serovar Typhimurium DT104. WPI films containing SA or PABA decreased L. monocytoge- nes, E. coli, and S. Typhimurium populations by 3.4 to 4.1, 3.1 to 3.6, and 3.1 to 4.1 logs, respectively, on both products after 21 d at 4 °C. Background flora was inhibited compared with controls. Film tensile strength decreased while % elongation remained unchanged following 72 h of product contact.
Relationship of structure to properties in surfactants. III. Adsorption at the solid‐liquid interface from aqueous solution

Surfactants adsorb onto solid substrates from aqueous solution by a number of different mechanisms: ion exchange, ion pairing, hydrogen bonding, physical adsorption by polarization or dispersion forces. The relationship of the mechanism of adsorption to such factors as the nature of the solid substrate, the molecular structure of the surface active adsorbate, and the pH, electrolyte content, or other additive content of the aqueous phase is discussed. The effect of structural groups in the surfactant molecule on the efficiency, effectiveness, and rate of adsorption onto various types of solid substrates, charged, polar, and nonpolar, is reviewed and explained, and typical adsorption isotherms are presented. Adsorption of surfactant affects the properties of the solid substrate, such as hydrophilic or hydrophobic character, dispersibility, and reactivity towards reagents and dyes. These effects are discussed and explained.
Cell-free synthesis of Rauscher murine leukemia virus "gag" and "gag-pol" precursor polyproteins from virion 35 S RNA in a mRNA-dependent translation system derived from mouse tissue culture cells.

Abstract Using a mRNA-dependent cell-free protein synthesis sytem derived from mouse tissue culture cell extracts by treatment with micrococcal nuclease, we have examined the capacity of 35S genomic RNA from Rauscher leukemia virus (RLV) to code for the synthesis of viral proteins. Analysis of the polypeptide product by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that RLV 358 RNA directed the synthesis of RLV-specific polypeptides of 55,000, 65,000, 75,000, and 200,000 apparent molecular weights, identical in size to the known intracellular precursors of the RLV mature polypeptides. None of the individual mature virus proteins appeared to be synthesized. If canavanine, an arginine analogue, was substituted for arginine under conditions for cell-free protein synthesis, a RLV-specific polypeptide with a molecular weight of approximately 80,000 was synthesized at the expense of the 65,000 and 75,000 MW polypeptides. Monospecific antisera directed against p30, p15, p12, and p10 recognized the 65,000, 75,000, 80,000 and 200,000 MW polypeptides, indicating that each shared antigenic determinants with all of these “gag” proteins. Using the appropriate authentic RLV precursor polypeptides as standards, comparative tryptic maps were performed with the [ 3 H]tyrosine or [ 35 Snine-labeled in vitro -synthesized 65,000 and 200,000 MW polypeptides. The 65,000 MW polypeptide was found to be identical to Pr658 gag , 2 a 65,000 MW RLV gag protein precursor obtained from infected cells by immunoprecipitation and gel electrophoresis. The 200,000 MW in vitro -synthesized polypeptide was found to contain methionine-labeled tryptic peptides characteristic of the RLV reverse transcriptase (“pol”) and p30.
PAU: PARSING AND UNDERSTANDING WITH UNIFORM SYNTACTIC, SEMANTIC, AND IDIOMATIC REPRESENTATIONS

PAU is an all-paths chart-based unification parser that uses the same uniform representation for regular syntax, irregular syntax such as idioms, and semantics. PAU's representation has very little redundancy, simplifying the task of adding new semantics and syntax fo PAU's knowledge base. PAU uses relations between the syntax and semantics to avoid the proliferation of rules found in semantic grammars. By encoding semantics at the same level of representation as syntax, PAU is able to use semantic constraints early in the parse to eliminate semantically anomalous syntactic interpretations. Examples are given to show how PAU can handle the many eccentricities of different idioms using the same mechanisms as are used to handle regular syntax and semantics. These include the ability of some idioms, but not other idioms of the same syntactic form to undergo passivization, particle movement, action nominalization, indirect object movement, modification by adjectives, gerundive nominalization, prepositional phrase preposing, and topicalization. PAU's representation is bidirectional and is also used by a companion generator. PAU is designed to be efficient, runs in real time on typical workstations, and is being used in a number of natural language systems.
An Illustration of Household Energy-Conservation Modeling Using the Search-List Decision-Heuristic

Much debate has focused on the appropriateness of the rational paradigm and its mathematical manifestation—utility theory—as a foundation for descriptive models of human behavior. Comparative discussion has been hampered by a lack of mathematically based noneconomic decision models. Such a model is presented in this paper, derived from the search-list decision-heuristic, that describes household decisions concerning energy-conservation investments. The model was estimated with energy use, demographic, and energy audit data collected in 1982 from households in the state of Connecticut, USA.
Acute, Symptomatic Atrial Fibrillation after Sildenafil Citrate Therapy in a Patient with Hypertrophic Obstructive Cardiomyopathy

This case report describes a patient with hypertrophic cardiomyopathy who developed symptomatic atrial fibrillation on two occasions after ingesting sildenafil citrate (Viagra). Sildenafil citrate should be withheld or used with extreme caution in persons with hypertrophic obstructive cardiomyopathy.
Quantitative magnetic resonance imaging of the mdx mouse model of Duchenne muscular dystrophy.

ABSTRACT: The mdx mouse has a genetically homologous disease toDuchenne muscular dystrophy in humans. The disease progression, how-ever, is not accompanied by the same level of fatty infiltration and muscledegeneration as occurs in humans. Thus, the presence of histological/pathological changes in living mdx mice has been difficult to monitor. Wequantified proton density and the T2 relaxation time of protons with a reso-lution of 195 × 195 × 1000 µm using multiecho magnetic resonance (MR)imaging at 7 Tesla. These relaxation data were correlated with water contentin both muscle and brain of mdx and controls. No differences were observedin brain. The mdx muscles had increased water content and proton densityand decreased T2 relative to controls. These data indicate that there areintrinsic changes in T2 (opposite to that which would be induced by fattyinfiltration) and suggest that T2 imaging could be used to monitor progres-sion and treatment in this animal model. © 1999 John Wiley & Sons, Inc. Muscle Nerve22: 1367–1371, 1999
DFBA-LQR: An Optimal Control Approach to Flux Balance Analysis

Systems biology is becoming an emerging field, as systems science is demonstrated as an essential tool in untangling biocomplexity. While various steady-state-based methods have been developed for study of metabolic networks, the study of the network dynamics is a less explored area, as it is inherently related to the regulatory network. The difficulty of regulatory network inference opens up the possibility of employing control techniques and methods for analysis of metabolic networks. In this work, the potential for application of optimal control theory to metabolic control problems is investigated. Considering that the regulatory network in essence is a cascade control structure, the proposed modeling approach relies on the postulate that evolution is a genetic optimization scheme leading to “optimal” regulatory networks. Thus the approach utilizes a modified linear quadratic regulator formulation to evaluate the optimal regulatory network for a given flux model. Utilizing a homeostasis-type objective,...
New CAD issues and considerations for the design of mixed-signal SOCs

By 2006, close to 75% of system on a chip (SOC) designs will be mixed-signal in nature with digital, analog and possibly RF circuitry all integrated on a single chip. This paper will cover recommended design flows and the design methodology challenges facing current mixed signal SOC designers. It also addresses the CAD tool interoperability issues for these types of mixed-signal designs and identifies the work and solution that need to be done to enable their fast design turnaround.
Structure of trifunctional THI20 from yeast

In a recently characterized thiamin-salvage pathway, thiamin-degradation products are hydrolyzed by thiaminase II, yielding 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP). This compound is an intermediate in thiamin biosynthesis that, once phosphorylated by an HMP kinase, can be used to synthesize thiamin monophosphate. Here, the crystal structure of Saccharomyces cerevisiae THI20, a trifunctional enzyme containing an N-terminal HMP kinase/HMP-P kinase (ThiD-like) domain and a C-terminal thia­min­ase II (TenA-like) domain, is presented. Comparison to structures of the monofunctional enzymes reveals that while the ThiD-like dimer observed in THI20 resembles other ThiD structures, the TenA-like domain, which is tetrameric in all previously reported structures, forms a dimer. Similarly, the active site of the ThiD-like domain of THI20 is highly similar to other known ThiD enzymes, while the TenA-like active site shows unique features compared with previously structurally characterized TenAs. In addition, a survey of known TenA structures revealed two structural classes, both of which have distinct conserved features. The TenA domain of THI20 possesses some features of both classes, consistent with its ability to hydrolyze both thiamin and the thiamin-degradation product 2-methyl-4-amino-5-aminomethylpyrimidine.
Ámbitos sociales compartidos: convergencia evolutiva en la Prehistoria y la práctica contemporánea

In this article, I distinguish between evolutionary and historica1 perspectives on the past, adopting the concept of “social fields” to argue for a macrohistorical interpretation of the archaeological record. The unit of analysis is not an archaeological culture or civilization but social groups inextricably involved with other groups in weblike interconnections in which technologies are diffused and modified by other groups caught up in these same processes. Such interconnections can best be traced archaeologically by examining the spread of technologies and subsistence practices. Other macrohistorical perspectives on the past, such as world systems analysis, often demand too much of the archaeological record and are used anachronistically. Prehistory documents the ever-increasing participation of groups in social fields that ultimately converge. I conclude by emphasizing the need for a perspective on the past that emphasizes its shared nature in which all peoples have contributed and benefited from interactions with their neighbours.
Vaccination with different HSV-1 glycoproteins induces different patterns of ocular cytokine responses following HSV-1 challenge of vaccinated mice.

Abstract We previously reported that vaccination of BALB/c mice with different baculovirus expressed HSV-1 glycoproteins induced varying degrees of protection against HSV-1 ocular challenge, ranging from complete protection to no protection, to exacerbation of eye disease. To correlate specific local immune responses with protection and exacerbation of corneal scarring, we examined immune cell infiltrates in the cornea after ocular HSV-1 challenge of vaccinated mice. Mice were vaccinated with gD, which completely protects against corneal scarring, gG, which produces no protection against corneal scarring, or gK, which exacerbates corneal scarring. Cryostat sections of cornea were taken at different times after challenge and examined for infiltrating cells containing IL-2, IL-4, IFN- γ , IL-6, or TNF- α . No corneal infiltrates were seen before challenge or 1 day after ocular challenge in any groups. By days 3–7, many cells containing IL-4 and IFN- γ , but few cells containing IL-2, had infiltrated into the corneas of gG or mock vaccinated mice. At the same times, many cells containing IL-2, but few cells containing IL-4 or IFN- γ , were seen in the corneas of gD vaccinated mice. In contrast, the corneas of mice vaccinated with gK contained large amounts of IL-2, IFN- γ , and IL-4. Our results suggest that: (1) corneas from gD vaccinated mice had no corneal disease and developed a response highly biased toward IL-2 responses; (2) corneas from gG or mock vaccinated eyes had significant corneal disease and developed a mostly IL-4 and IFN- γ cytokine response; and (3) corneas from gK vaccinated mice had exacerbated corneal disease and developed strong IL-2, IL-4 and IFN- γ cytokine responses.