2,973 research outputs found
Temperature Dependent Neutron Scattering Sections for Polyethylene
This note presents neutron scattering cross sections for polyethylene at 296
K, 77 K and 4 K derived from a new scattering kernel for neutron scattering off
of hydrogen in polyethylene. The kernel was developed in ENDF-6 format as a set
of S(alpha,beta) tables using the LEAPR module of the NJOY94 code package. The
polyethylene density of states (from 0 to sub eV) adopted to derive the new
kernel is presented. We compare our calculated room temperature total
scattering cross sections and double differential cross sections at 232 meV at
various angles with the available experimental data (at room temperature), and
then extrapolate the calculations to lower temperatures (77K and 4K). The new
temperature dependent scattering kernel gives a good quantitative fit to the
available room temperature data and has a temperature dependence that is
qualitatively consistent with thermodynamics.Comment: 6 page
Trowelable ablative coating composition and method of use
A trowelable ablative coating composition is disclosed. The composition comprises an epoxy resin, an amide curing agent, glass microspheres and ground cork. A method for protecting a substrate is also disclosed. The method comprises applying the trowelable ablative coating discussed above to a substrate and curing the coating composition
Fabric Parameters and Pesticide Characteristics That Impact on Dermal Exposure of Applicators
Fabric functional finish and formulation of pesticides are factors that contribute to pesticide wicking, wetting, and penetration. Fluorocarbon soil-repellent finishes inhibit contamination of the fabric and of sentinel pads. An undergarment layer offers better protection than does a single layer. Spun-bonded olefin offers protection of the same magnitude as soil-repellent finishes. Methyl parathion residues after laundering were similar for the unfinished fabric, the durable-press finished fabric, and the soil-repellent finished fabric, but the initial contamination of the soil-repellent finished fabric was only 20~ of that of the other two fabrics
Structural associations of symptomatic knee osteoarthritis
Objective
Structural changes of osteoarthritis (OA) may occur in the absence of pain. In this study, we aimed to identify histopathologic features that are associated with symptomatic knee OA.
Methods
Medial tibial plateaus and synovium samples were obtained at the time of total knee replacement (TKR) surgery for OA (advanced OA group) or were obtained postmortem from subjects who had not sought medical attention for knee pain during the last year of life (non-OA control group). To identify features of OA, we compared the patients with advanced OA with the age-matched non-OA controls (n = 26 per group). To identify OA features associated with symptoms, we compared two additional groups of subjects who were matched for severity of chondropathy (n = 29 per group): patients undergoing TKR for symptomatic OA (symptomatic chondropathy group) and postmortem subjects with similar severity of chondropathy who were asymptomatic during the last year of life (asymptomatic chondropathy group). The histologic features of the samples were graded, and immunoreactivities for macrophages (CD68) and nerve growth factor (NGF) in the synovium were quantified. The cellular localization of synovial NGF was determined by double immunofluorescence analysis.
Results
Advanced OA cases displayed more severe changes in the synovium (synovitis, increased synovial NGF, and CD68-immunoreactive macrophages) and cartilage (loss of cartilage surface integrity, loss of proteoglycan, tidemark breaching, and alterations in chondrocyte morphology) than did the non-OA controls. Synovial NGF was localized predominantly to fibroblasts and to some macrophages. The symptomatic chondropathy group displayed greater levels of synovitis, synovial NGF, and loss of cartilage integrity, in addition to alterations in chondrocyte morphology, than did the asymptomatic chondropathy group (P < 0.05 for each comparison).
Conclusion
Synovitis, increased synovial NGF, alterations in chondrocyte morphology, and loss of cartilage integrity are features of knee OA that may be associated with symptoms
Behaviour and the safety of older people on stairs
Behaviour and the safety of older people on stair
A simple method to derive speed for the endurance shuttle walk test
Background: The original method for determining endurance shuttle walk test (ESWT) speed involves components that are time consuming for clinicians. We sought to determine: (i) whether components described in the original method for determining ESWT speed held true and; (ii) the agreement between speeds derived using the original method and that equivalent to 85% of the peak speed achieved during the incremental shuttle walk test (ISWT). Methods: Patients with chronic obstructive pulmonary disease (COPD) performed two ISWTs and one ESWT on separate days, wearing a calibrated portable gas analysis unit. A retrospective analysis of these data allowed us to determine whether: (i) the peak rate of oxygen uptake (VO2peak) can be accurately estimated from the incremental shuttle walk distance (ISWD) and; (ii) ESWTs performed at a speed derived using the original method elicited 85% of VO2peak. Agreement between walks speeds was determined using BlandâAltman analysis. Results: Twenty-two participants (FEV1 48 ± 13% predicted, age 66 ± 8 yr) completed the study. The VO2peak estimated from the ISWD was less than that measured during the ISWT (mean difference â4.4; 95% confidence interval (CI), â6.0 to â2.9 mlâą kgâ1âąminâ1). The ESWT and ISWT elicited similar VO2peak (mean difference â0.2; 95% CI, â1.5 to 1.2 mlâąkgâ1âąminâ1). The mean difference (±limits of agreement) between ESWT speeds was 0.15 (±0.34) kmâąhâ1. Conclusions: Components of the original method for determining the ESWT speed did not hold true in our sample. ESWT speed can be derived by calculating 85% of the peak speed achieved during the ISWT
Safety of older people on stairs : behavioural factors
Falling on steps and stairs in the home is a serious problem for older people aged 65 and
over, both in terms of the high frequency with which these accidents occur and their
consequences. Although previous research has increased knowledge of personal and
environmental factors involved in falls on stairs, behavioural aspects have received less
attention. The aini of this investigation, therefore, was to improve understanding of how
older people keep and use their stairs, and to assess the iniplications for stair safety.
Interviews were conducted with 157 older people, aged between 65-96 years, in their own
homes. Using a conibination of open and closed questions, participants were asked about
their behaviour on and around thc stairs, awareness of safety factors and any history of
falling on stairs. During each visit, information was collected about the stairs in the home
including design and repair of stair coverings, number of handrails and thcir condition,
objects on and around the stairs, lighting, and position of windows. Standard
mthropometric dimensions of interviewees were recorded, along with other measurements
including grip strength, ability to get up from a stool without using hands, and measures of
visual acuity and depth perception
Dielectric Screening in a Spherical Cavity
In this work we examine the electrostatic screening potential due to a point
charge located off-centre in a spherical dielectric cavity. This potential is
expanded for the case in which the dielectric constant is large,
several methods of finding the terms in the expansion are investigated, and
closed-form expressions are found through third order in along with
error bounds. Finally, possible uses of these expressions in molecular dynamics
simulations of isolated charged molecules is discussed.Comment: 15 Pages, 5 Figures, To be submitted to J. Phys. A. Uses iopart.cl
Middle Jurassic fossils document an early stage in salamander evolution
Salamanders are an important group of living amphibians and model organisms for understanding locomotion, development, regeneration, feeding, and toxicity in tetrapods. However, their origin and early radiation remain poorly understood, with early fossil stem-salamanders so far represented by larval or incompletely known taxa. This poor record also limits understanding of the origin of Lissamphibia (i.e., frogs, salamanders, and caecilians). We report fossils from the Middle Jurassic of Scotland representing almost the entire skeleton of the enigmatic stem-salamander Marmorerpeton. We use computed tomography to visualize high-resolution three-dimensional anatomy, describing morphologies that were poorly characterized in early salamanders, including the braincase, scapulocoracoid, and lower jaw. We use these data in the context of a phylogenetic analysis intended to resolve the relationships of early and stem-salamanders, including representation of important outgroups alongside data from high-resolution imaging of extant species. Marmorerpeton is united with Karaurus, Kokartus, and others from the Middle JurassicâLower Cretaceous of Asia, providing evidence for an early radiation of robustly built neotenous stem-salamanders. These taxa display morphological specializations similar to the extant cryptobranchid âgiantâ salamanders. Our analysis also demonstrates stem-group affinities for a larger sample of Jurassic species than previously recognized, highlighting an unappreciated diversity of stem-salamanders and cautioning against the use of single species (e.g., Karaurus) as exemplars for stem-salamander anatomy. These phylogenetic findings, combined with knowledge of the near-complete skeletal anatomy of Mamorerpeton, advance our understanding of evolutionary changes on the salamander stem-lineage and provide important data on early salamanders and the origins of Batrachia and Lissamphibia
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