A Regular Demand System with Commodity-Specific Demographic Effects

Regular consumer demand systems almost invariably employ specifications that involve common functional forms in all equations. When applications involve crosssectional data it is often the case that demographic effects are important. However it is plausible that demographic effects are commodity-specific. In this case, there may be a loss of efficiency if a common functional form across commodities is imposed artificially by entering redundant explanators in demand equations for which specific demographic influences are unwarranted. This paper explores an approach to specifying a complete system of demand equations which is fully regular but which nevertheless allows for commodity-specific variation in the functional form of the demand equations.Consumer Economics: Theory, Consumer Economics: Empirical Analysis, Demographic Economics

Genomic Approaches to the Study of HIV-1 Acquisition

Host genome studies are increasingly available for the study of infectious disease susceptibility. Current technologies include large-scale genotyping, genome-wide screens such as transcriptome and silencing (silencing RNA) studies, and increasingly, the possibility to sequence complete genomes. These approaches are of interest for the study of individuals who remain uninfected despite documented exposure to human immunodeficiency virus type 1. The main limitation remains the ascertainment of exposure and establishing large cohorts of informative individuals. The pattern of enrichment for CCR5 Δ32 homozygosis should serve as the standard for assessing the extent to which a given cohort (of white subjects) includes a large proportion of exposed uninfected individual

Dispositional optimism and suicide among trans and gender diverse adults

Trans and gender diverse adults are at increased suicide risk. Optimism protects against suicide across multiple populations. Applying the Interpersonal-Psychological Theory of Suicide (IPTS), we examined both factors among 237 adults recruited via social media and online platforms, 79.3% of whom reported serious suicide ideation. Dispositional optimism predicted suicidal ideation and behaviors (SIB), but did not moderate the relationship between the IPTS components and SIB. After controlling for depressive symptoms, hormone therapy and gender-affirming surgery did not predict SIB. Promoting dispositional optimism within a therapeutic framework may reduce SIB in this vulnerable population

Artificial grass: A conceptual model for degradation in performance

AbstractArtificial grass pitches (AGPs), with long fibres and sand and rubber infill, have seen growth within many sports at both professional and community levels. Academic research has tended to focus on athleticism, injuries and the development of equipment and test standards, while research and development for the turf, infill and shockpad layers has generally been undertaken by the manufacturers. This has led to an under researching and / or reporting of the factors influencing AGP degradation and the subsequent effects on pitch performance. Long term testing has shown that as rubber filled AGPs age their performance worsens; they generally become harder and play faster with ball roll often reported as one of the first standards to be affected. This paper presents a hypothesised model to describe the numerous factors causing degradation and their effects on performance. It is designed as a useful tool for research aimed at assessing and improving current maintenance operations which will ultimately lead to increasing the useful life of AGPs

Prevalence of iron deficiency in 62,685 women of seven race/ethnicity groups: The HEIRS Study.

BackgroundFew cross-sectional studies report iron deficiency (ID) prevalence in women of different race/ethnicity and ages in US or Canada.Materials and methodsWe evaluated screening observations on women who participated between 2001-2003 in a cross-sectional, primary care-based sample of adults ages ≥25 y whose observations were complete: race/ethnicity; age; transferrin saturation; serum ferritin; and HFE p.C282Y and p.H63D alleles. We defined ID using a stringent criterion: combined transferrin saturation <10% and serum ferritin <33.7 pmol/L (<15 μg/L). We compared ID prevalence in women of different race/ethnicity subgrouped by age and determined associations of p.C282Y and p.H63D to ID overall, and to ID in women ages 25-44 y with or without self-reported pregnancy.ResultsThese 62,685 women included 27,079 whites, 17,272 blacks, 8,566 Hispanics, 7,615 Asians, 449 Pacific Islanders, 441 Native Americans, and 1,263 participants of other race/ethnicity. Proportions of women with ID were higher in Hispanics and blacks than whites and Asians. Prevalence of ID was significantly greater in women ages 25-54 y of all race/ethnicity groups than women ages ≥55 y of corresponding race/ethnicity. In women ages ≥55 y, ID prevalence did not differ significantly across race/ethnicity. p.C282Y and p.H63D prevalence did not differ significantly in women with or without ID, regardless of race/ethnicity, age subgroup, or pregnancy.ConclusionsID prevalence was greater in Hispanic and black than white and Asian women ages 25-54 y. p.C282Y and p.H63D prevalence did not differ significantly in women with or without ID, regardless of race/ethnicity, age subgroup, or pregnancy

Time-course changes associated with PA Lumbar Mobilizations on Lumbar and Hamstring Range of Motion:A Randomized Controlled Crossover Trial

Objective: We aimed to compare the post-intervention time-course changes in active knee extension (AKE) and active lumbar flexion (ALF) range of motion in response to unilateral posterior–anterior (UPA) mobilizations of the lumbar spine (L4/5 zygapophyseal). Methods: Twenty-four asymptomatic participants (maleness: 0.58, age [mean ± standard deviation]: 32 ± 8 years, body mass index 25.9 ± 2.6 kg m2) were recruited to a fully controlled crossover trial. Following either the intervention (L4/5 zygapophyseal mobilizations) or control, participants immediately performed the AKE and ALF tests, which were also performed at baseline. Subsequent tests were made at intervals of 5, 10, 15, 20, 25, 30, 45 and 60 min. Results: After adjustment for baseline (mean AKE: 37.2° from full extension, mean ALF: 14.37 cm), sex and age, UPA lumbar mobilizations had a most likely moderate effect on AKE (9.8° closer to full extension; ±1.9) and a likely moderate effect on ALF (1.34 cm; ±90% confidence limits 0.43). The magnitude of the AKE effect became most likely small 20-min posttreatment (5.3; ±1.7) and possibly small/possibly trivial 60-min posttreatment (2.1; ±1.4). For ALF, the magnitude of the effect became most likely small 15-min posttreatment (0.76; ±0.25), possibly small/possibly trivial 25-min posttreatment (0.38; ±0.18) and likely trivial 60-min posttreatment (0.26; ±1.8). Discussion: UPA lumbar mobilizations increased lumbar Range of Motion and hamstring extensibility by a moderate magnitude, with the effect reducing after 10–20-min posttreatment. Clinicians should consider these time-course changes when applying UPA lumbar mobilizations

Artificial grass: a longitudinal study on ball roll and free pile height

Ball roll is seen as one of the first criterion which cause artificial grass pitches to fail performance standards. Previous research has demonstrated that the ball roll distance increased after a seven-year period. However, there is a lack of understanding in the mechanisms causing the ball roll distance to increase with time. During this study, the ball roll distance and free pile height were measured over a twelve-month period on an indoor pitch. The aim was to evaluate the early-life pitch performance and to determine if a correlation existed between ball roll distance and free pile height. The indoor environment protected the measurements from the confounding effects of wind and precipitation, providing a controlled environment in which to assess the effects of mechanical wear from player usage on both ball roll and free pile height. There was a general trend for the ball roll distance to increase and the free pile height to reduce with time. There was a strong, negative correlation (R= -0.967) between ball roll distance and free pile height. The ball roll distance increased above the FIFA 2* limit within the first twelve months of pitch life, however intervening drag brushing the surface was found to reduce ball roll distance to within the requirements, signifying the importance of regular drag brushing. Significant spatial variation (P<0.001) existed in ball roll and free pile height between high use and low use areas of the pitch. The study provides strong evidence on the effects of free pile height on the ball roll distance, indicating that pitch owners need effective maintenance to ensure the carpet pile remains upright to maintain ball roll distance to meet performance standards

Understanding the effects of decompaction maintenance on the infill state and play performance of third-generation artificial grass pitches

Third generation artificial grass pitches have been observed to get harder over time. The maintenance technique of rubber infill decompaction is intended to help slow, or reverse, this process. At present, little is understood about either the science of the infill compaction process or the efficacy of decompaction maintenance. The objective of this study was to measure the changes in rubber infill net bulk density, force reduction (impact absorption) and vertical ball rebound under various levels of compactive effort in controlled laboratory-based testing. The assessments were repeated after the systems had been raked to simulate the decompaction maintenance techniques. These tests defined the limits of compaction (loose to maximally compacted) in terms of the change in rubber infill net bulk density, force reduction and vertical ball rebound. Site testing was also undertaken at four third generation pitches immediately pre and post decompaction, to determine the measurable effects in the less well controlled field environment. Rubber infill net bulk density was found to increase as compactive effort increased, resulting in increased hardness. Decompacting the surface was found to approximately fully reverse these effects. In comparison, the site measurements demonstrated similar but notably smaller magnitudes of change following the decompaction process suggesting that the field state pre and post decompaction did not reach the extremes obtained in the laboratory. The findings suggest that rubber infill net bulk density is an important parameter influencing the hardness of artificial grass and that decompactions can be an effective method to reverse compaction related hardness changes

Artificial grass: a longitudinal study on ball roll and free pile height

Ball roll is seen as one of the first criterion which cause artificial grass pitches to fail performance standards. Previous research has demonstrated that the ball roll distance increased after a seven-year period. However, there is a lack of understanding in the mechanisms causing the ball roll distance to increase with time. During this study, the ball roll distance and free pile height were measured over a twelve-month period on an indoor pitch. The aim was to evaluate the early-life pitch performance and to determine if a correlation existed between ball roll distance and free pile height. The indoor environment protected the measurements from the confounding effects of wind and precipitation, providing a controlled environment in which to assess the effects of mechanical wear from player usage on both ball roll and free pile height. There was a general trend for the ball roll distance to increase and the free pile height to reduce with time. There was a strong, negative correlation (R= -0.967) between ball roll distance and free pile height. The ball roll distance increased above the FIFA 2* limit within the first twelve months of pitch life, however intervening drag brushing the surface was found to reduce ball roll distance to within the requirements, signifying the importance of regular drag brushing. Significant spatial variation (P<0.001) existed in ball roll and free pile height between high use and low use areas of the pitch. The study provides strong evidence on the effects of free pile height on the ball roll distance, indicating that pitch owners need effective maintenance to ensure the carpet pile remains upright to maintain ball roll distance to meet performance standards

Interaction of the Host and Viral Genome and Their Influence on HIV Disease

The course of Human Immunodeficiency Virus type 1 (HIV) infection is a dynamic interplay in which both host and viral genetic variation, among other factors, influence disease susceptibility and rate of progression. HIV set-point viral load (spVL), a key indicator of HIV disease progression, has an estimated 30% of variance attributable to common heritable effects and roughly 70% attributable to environmental factors and/or additional non-genetic factors. Genome-wide genotyping and sequencing studies have allowed for large-scale association testing studying host and viral genetic variants associated with infection and disease progression. Host genomics of HIV infection has been studied predominantly in Caucasian populations consistently identifying human leukocyte antigen (HLA) genes and C-C motif chemokine receptor 5 as key factors of HIV susceptibility and progression. However, these studies don’t fully assess all classes of genetic variation (e.g., very rare polymorphisms, copy number variants etc.) and do not inform on non-European ancestry groups. Additionally, viral sequence variability has been demonstrated to influence disease progression independently of host genetic variation. Viral sequence variation can be attributed to the rapid evolution of the virus within the host due to the selective pressure of the host immune response. As the host immune system responds to the virus, e.g., through recognition of HIV antigens, the virus is able to mitigate this response by evolving HLA-specific escape mutations. Diversity of viral genotypes has also been correlated with moderate to strong effects on CD4+ T cell decline and some studies showing weak to no correlation with spVL. There is evidence to support these viral genetic factors being heritable between individuals and the evolution of these factors having important consequences in the genetic epidemiology of HIV infection on a population level. This review will discuss the host-pathogen interaction of HIV infection, explore the importance of host and viral genetics for a better understanding of pathogenesis and identify opportunities for additional genetic studies