Heat transport across interfaces is often discussed in terms of the transmission probability of the heat-carrying phonons through the contact zone. Although interface roughness influences the true ...contact area and affects phonon scattering within the contact zone, its effect on nanoscale heat transport remains poorly understood. Here, we report experimental data on the pressure dependence of thermal transport across polished nanoscale contacts. The data can be quantitatively explained by a model of thermal conductance across interfaces that incorporates the effect of nanoscale roughness through the quantized thermal conductance across individual atomic-scale contacts within the contact zone.
Individual level response to natural and anthropogenic disturbance represents an increasingly important, but as yet little understood, component of animal behavior. Disturbance events often alter ...habitat, which in turn can modify behaviors of individuals in affected areas, including changes in habitat use and associated changes in social structure. To better understand these relationships, we investigated aspects of habitat selection and social connectivity of a small passerine bird, the red-backed fairywren (Malurus melanocephalus), before vs. after naturally occurring fire disturbance in Northern Territory, Australia. We utilized a social network framework to evaluate changes in social dynamics pre- vs. post-fire. Our study covered the non-breeding season in two consecutive years in which fires occurred, and individuals whose habitat was affected and those that were not affected by fire. Individuals in habitat affected by fires had stronger social ties (i.e. higher weighted degree) after fires, while those that were in areas that were not affected by fire actually had lower weighted degree. We suggest that this change in social connections may be linked to habitat. Before fires, fairywrens used habitat that had similar grass cover to available habitat plots randomly generated within our study site. Fire caused a reduction in grass cover, and fairywrens responded by selecting habitat with higher grass cover relative to random plots. This study demonstrates how changes in habitat and/or resource availability caused by disturbance can lead to substantive changes in the social environment that individuals experience.
MeV-scale energy depositions by low-energy photons produced in neutrino-argon interactions have been identified and reconstructed in ArgoNeuT liquid argon time projection chamber (LArTPC) data. ...ArgoNeuT data collected on the NuMI beam at Fermilab were analyzed to select isolated low-energy depositions in the TPC volume. The total number, reconstructed energies, and positions of these depositions have been compared to those from simulations of neutrino-argon interactions using the fluka Monte Carlo generator. Measured features are consistent with energy depositions from photons produced by deexcitation of the neutrino’s target nucleus and by inelastic scattering of primary neutrons produced by neutrino-argon interactions. This study represents a successful reconstruction of physics at the MeV scale in a LArTPC, a capability of crucial importance for detection and reconstruction of supernova and solar neutrino interactions in future large LArTPCs.
The novel coronavirus pandemic has set in high relief the entrenched health, social, racial, political, and economic inequities within American society as the incidence of severe morbidity and ...mortality from the disease caused by the virus appears to be much greater in black and other racial/ethnic minority populations, within homeless and incarcerated populations, and in lower-income communities in general. The reality is that the United States is ill equipped to realize health equity in prevention and control efforts for any type of health outcome, including an infectious disease pandemic. In this article, the authors address an important question: When new waves of the current pandemic emerge, or another novel pandemic emerges, how can the United States be better prepared and also ensure a rapid response that reduces rather than exacerbates social and health inequities? The authors argue for a health equity framework to pandemic preparedness that is grounded in meaningful community engagement and that, while recognizing the fundamental causes of social and health inequity, has a clear focus on upstream and midstream preparedness and downstream rapid response efforts that put social and health equity at the forefront.
Descriptive data have revealed significant racial/ethnic disparities in coronavirus disease 2019 (COVID-19) cases in the US, but underlying mechanisms of disparities remain unknown.
To examine the ...association between county-level sociodemographic risk factors and US COVID-19 incidence and mortality.
This cross-sectional study analyzed the association between US county-level sociodemographic risk factors and COVID-19 incidence using mixed-effects negative binomial regression, and COVID-19 mortality using zero-inflated negative binomial regression. Data on COVID-19 incidence and mortality were collected from January 20 to July 29, 2020. The association of social risk factors with weekly cumulative incidence and mortality was also examined by interacting time with the index measures, using a random intercept to account for repeated measures.
Sociodemographic data from publicly available data sets, including the US Centers for Disease Control and Prevention's Social Vulnerability Index (SVI), which includes subindices of socioeconomic status, household composition and disability, racial/ethnic minority and English language proficiency status, and housing and transportation.
As of July 29, 2020, there were a total of 4 289 283 COVID-19 cases and 147 074 COVID-19 deaths in the US. An increase of 0.1 point in SVI score was associated with a 14.3% increase in incidence rate (incidence rate ratio IRR, 1.14; 95% CI, 1.13-1.16; P < .001) and 13.7% increase in mortality rate (IRR, 1.14; 95% CI, 1.12-1.16; P < .001), or an excess of 87 COVID-19 cases and 3 COVID-19 deaths per 100 000 population for a SVI score change from 0.5 to 0.6 in a midsize metropolitan county; subindices were also associated with both outcomes. A 0.1-point increase in the overall SVI was associated with a 0.9% increase in weekly cumulative increase in incidence rate (IRR, 1.01; 95% CI, 1.01-1.01; P < .001) and 0.5% increase in mortality rate (IRR, 1.01; 95% CI, 1.01-1.01; P < .001).
In this cross-sectional study, a wide range of sociodemographic risk factors, including socioeconomic status, racial/ethnic minority status, household composition, and environmental factors, were significantly associated with COVID-19 incidence and mortality. To address inequities in the burden of the COVID-19 pandemic, these social vulnerabilities and their root causes must be addressed.
Exposure to radon is the second leading cause of lung cancer, and the risk is significantly higher for smokers than for nonsmokers. More than 85% of radon-induced lung cancer deaths are among ...smokers. The most powerful approach for reducing the public health burden of radon is shaped by 2 overarching principles: public communication efforts that promote residential radon testing and remediation will be the most cost effective if they are primarily directed at current and former smokers; and focusing on smoking prevention and cessation is the optimal strategy for reducing radon-induced lung cancer in terms of both public health gains and economic efficiency. Tobacco control policy is the most promising route to the public health goals of radon control policy.
Population health, defined broadly as the distribution of health‐related risks and outcomes within and across populations, has been developing as a subject of scientific inquiry and public health ...practice for more than two centuries. More recent attention has been fueled by the growing understanding of both upstream (macro‐level) and downstream (micro‐level) social determinants of health, and increased recognition of the limits of medical care in reducing socially driven health disparities. A robust finding from population health research is that the United States spends a much greater percentage of its GDP on medical care than any other developed country, yet ranks quite low in broad population‐level indicators of health status, including life expectancy and infant mortality. In response, the Institute for Healthcare Improvement introduced the Triple Aim framework in 2007 to optimize health care system performance: reduce costs, improve quality, and improve population health.
This article overviews previously published and ongoing research from the Americans' Changing Lives (ACL) Study, a longitudinal study of a nationally representative sample of 3,617 adults aged 25 ...years and older when first interviewed in 1986, focusing on socioeconomic disparities in the way health changes with age during middle and later life, especially in terms of compression of morbidity/functional limitations.
A variety of descriptive and multivariate regression and growth curve analyses are done on the ACL sample, now surveyed over four waves spanning 15.5 years between 1986 and 2001/2002 with continuing mortality ascertainment via the National Death Index, death certificate searches, and informant reports.
Both cross-sectional and longitudinal analyses indicate that socioeconomic disparities in health are small in early adulthood, increase through middle and early old age, and then lessen again in later old age. In other terms, compression of morbidity/functional limitations into the later stages of the life course is realized to a much greater degree among the better educated compared with the less educated. Cross-sectional evidence suggests that this reflects differential exposure to or experience of a wide range of psychosocial, environmental, and biomedical risk factors for health (and perhaps their differential impact at different ages and life stages), as well as variations in biological robustness and frailty and also perhaps in the strength of social welfare supports for health at different life stages. Longitudinal analyses reveal several new insights: (a) The flow of causality is much greater from socioeconomic position to health than vice versa; (b) education plays a greater role relative to income in the onset of functional limitations, whereas income has much stronger effects on their progression or course; and (c) educational disparities in the onset and hence of compression of functional limitations over the life course have increased strikingly in later middle and early old age (ages 55-84 years) since 1986.
The results indicate that understanding and alleviating social disparities in health are both theoretically and methodologically quintessential problems of life course analysis and research.
The current report examines the interactions of silver nanoparticles (Ag-NPs) with the cerebral microvasculature to identify the involvement of proinflammatory mediators that can increase blood-brain ...barrier (BBB) permeability. Primary rat brain microvessel endothelial cells (rBMEC) were isolated from adult Sprague-Dawley rats for an in vitro BBB model. The Ag-NPs were characterized by transmission electron microscopy (TEM), dynamic light scattering, and laser Doppler velocimetry. The cellular accumulation, cytotoxicity (6.25–50 μg/cm3) and potential proinflammatory mediators (interleukin IL-1β, IL-2, tumor necrosis factor TNF α, and prostaglandin E2 PGE2) of Ag-NPs (25, 40, or 80 nm) were determined spectrophotometrically, cell proliferation assay (2,3-bis2-methoxy-4-nitro-5-sulfophenyl-2H-tetrazolium-5-carboxanilide) and ELISA. The results show Ag-NPs–induced cytotoxic responses at lower concentrations for 25 and 40 nm when compared with 80-nm Ag-NPs. The proinflammatory responses in this study demonstrate both Ag-NPs size and time-dependent profiles, with IL-1B preceding both TNF and PGE2 for 25 nm. However, larger Ag-NPs (40 and 80 nm) induced significant TNF responses at 4 and 8 h, with no observable PGE2 response. The increased fluorescein transport observed in this study clearly indicates size-dependent increases in BBB permeability correlated with the severity of immunotoxicity. Together, these data clearly demonstrate that larger Ag-NPs (80 nm) had significantly less effect on rBMEC, whereas the smaller particles induced significant effects on all the end points at lower concentrations and/or shorter times. Further, this study suggests that Ag-NPs may interact with the cerebral microvasculature producing a proinflammatory cascade, if left unchecked; these events may further induce brain inflammation and neurotoxicity.
Many demographic, socioeconomic, and behavioral risk factors predict mortality in the United States. However, very few population-based longitudinal studies are able to investigate simultaneously the ...impact of a variety of social factors on mortality. We investigated the degree to which demographic characteristics, socioeconomic variables and major health risk factors were associated with mortality in a nationally-representative sample of 3617 U.S. adults from 1986 to 2005, using data from the 4 waves of the Americans' Changing Lives study. Cox proportional hazard models with time-varying covariates were employed to predict all-cause mortality verified through the National Death Index and death certificate review. The results revealed that low educational attainment was not associated with mortality when income and health risk behaviors were included in the model. The association of low income with mortality remained after controlling for major behavioral risks. Compared to those in the “normal” weight category, neither overweight nor obesity was significantly associated with the risk of mortality. Among adults age 55 and older at baseline, the risk of mortality was actually reduced for those were overweight (hazard rate ratio = 0.83) and those who were obese (hazard rate ratio = 0.68), controlling for other health risk behaviors and health status. Having a low level of physical activity was a significant risk factor for mortality (hazard rate ratio = 1.58). The results from this national longitudinal study underscore the need for health policies and clinical interventions focusing on the social and behavioral determinants of health, with a particular focus on income security, smoking prevention/cessation, and physical activity.
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