162 research outputs found

    Adsorption of Light Alkanes on the Surface of Substrates with Varying Symmetry and Composition

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    Adsorption plays an integral role in a variety of fundamentally and technologically important processes such as lubrication, gas separation and purification, wetting behavior, energy storage, heterogenous catalysis, biologically inspired materials, and the theory of phase transitions. As a result, adsorption phenomena are extensively studied in chemistry, physics, and biology each for uniquely different reasons. The homologous series of normal alkanes represent a class of organic molecules that are important in the fuel industry. From a fundamental perspective, the series of normal alkanes provide a route whereby physical and chemical properties relevant to adsorption can be examined with only subtle changes in molecular size and length. The alkanes also exhibit a well-known odd-even effect in some condensed phase physical properties. In the current study, the physical adsorption properties of the normal alkanes (methane-decane) on MgO, graphite, and boron nitride were investigated using volumetric adsorption isotherms and molecular dynamics simulations. This portion of the study focuses on determining the thermodynamics of adsorption as well as predicting the adsorption structures and dynamics. As a secondary study, the chemical adsorption of ethanol was examined on the surface of transition-phase aluminas using volumetric adsorption, temperature-programmed desorption, and inelastic neutron scattering. The purpose of this work was to observe the surface-catalyzed reaction of chemically bound ethanol with Lewis and Brø[oe]nsted acid sites present on the aluminas in-situ. The results of the projects described have significant implications in the design of new materials for gas separation and purification as well as heterogenous catalysis

    Multimorbidity: constellations of conditions across subgroups of midlife and older individuals, and related Medicare expenditures

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    Introduction: The Department of Health and Human Services’ 2010 Strategic Framework on Multiple Chronic Conditions called for the identification of common constellations of conditions in older adults. Objectives: To analyze patterns of conditions constituting multimorbidity (CCMM) and expenditures in a US representative sample of midlife and older adults (50–64 and ≥65 years of age, respectively). Design: A cross-sectional study of the 2010 Health and Retirement Study (HRS; n=17,912). The following measures were used: (1) count and combinations of CCMM, including (i) chronic conditions (hypertension, arthritis, heart disease, lung disease, stroke, diabetes, cancer, and psychiatric conditions), (ii) functional limitations (upper body limitations, lower body limitations, strength limitations, limitations in activities of daily living, and limitations in instrumental activities of daily living), and (iii) geriatric syndromes (cognitive impairment, depressive symptoms, incontinence, visual impairment, hearing impairment, severe pain, and dizziness); and (2) annualized 2011 Medicare expenditures for HRS participants who were Medicare fee-for-service beneficiaries (n=5,677). Medicaid beneficiaries were also identified based on their self-reported insurance status. Results: No large representations of participants within specific CCMM categories were observed; however, functional limitations and geriatric syndromes were prominently present with higher CCMM counts. Among fee-for-service Medicare beneficiaries aged 50–64 years, 26.7% of the participants presented with ≥10 CCMM, but incurred 48% of the expenditure. In those aged ≥65 years, these percentages were 16.9% and 34.4%, respectively. Conclusion: Functional limitations and geriatric syndromes considerably add to the MM burden in midlife and older adults. This burden is much higher than previously reported. Keywords: comorbidity, functional limitations, geriatric syndromes, multimorbidity, healthcare expenditure

    Multimorbidity: constellations of conditions across subgroups of midlife and older individuals, and related Medicare expenditures

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    Introduction: The Department of Health and Human Services’ 2010 Strategic Framework on Multiple Chronic Conditions called for the identification of common constellations of conditions in older adults. Objectives: To analyze patterns of conditions constituting multimorbidity (CCMM) and expenditures in a US representative sample of midlife and older adults (50–64 and ≥65 years of age, respectively). Design: A cross-sectional study of the 2010 Health and Retirement Study (HRS; n=17,912). The following measures were used: (1) count and combinations of CCMM, including (i) chronic conditions (hypertension, arthritis, heart disease, lung disease, stroke, diabetes, cancer, and psychiatric conditions), (ii) functional limitations (upper body limitations, lower body limitations, strength limitations, limitations in activities of daily living, and limitations in instrumental activities of daily living), and (iii) geriatric syndromes (cognitive impairment, depressive symptoms, incontinence, visual impairment, hearing impairment, severe pain, and dizziness); and (2) annualized 2011 Medicare expenditures for HRS participants who were Medicare fee-for-service beneficiaries (n=5,677). Medicaid beneficiaries were also identified based on their self-reported insurance status. Results: No large representations of participants within specific CCMM categories were observed; however, functional limitations and geriatric syndromes were prominently present with higher CCMM counts. Among fee-for-service Medicare beneficiaries aged 50–64 years, 26.7% of the participants presented with ≥10 CCMM, but incurred 48% of the expenditure. In those aged ≥65 years, these percentages were 16.9% and 34.4%, respectively. Conclusion: Functional limitations and geriatric syndromes considerably add to the MM burden in midlife and older adults. This burden is much higher than previously reported

    Acute involution in the tammar wallaby : identification of genes and putative novel milk proteins implicated in mammary gland function

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    AbstractMarsupials provide a suitable alternative model to studying mammary gland involution. They have evolved a different reproductive strategy from eutherians, giving birth to an altricial young and secreting milk that changes in composition during lactation. In this study, we used a marsupial-specific EST microarray to identify 47 up-regulated genes during mammary gland involution in the tammar wallaby (Macropus eugenii). These include the pro-apoptotic tumour necrosis factor receptor superfamily 21 (TNFRSF21) gene, whose expression in the mammary gland has not previously been reported. Genes encoding putative novel milk proteins which may protect the mammary gland from infection were also found to be up-regulated, such as amiloride binding protein 1 (ABP1), complement component 1QB (C1QB), complement component 4A (C4A) and colony stimulating factor 2 receptor β (CSF2Rβ). Our results show that the marsupial reproductive strategy was successfully exploited to identify genes and putative novel milk proteins implicated in mammary gland involution

    Western Bumble Bee: Declines in the Continental United States and Range-Wide Information Gaps

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    In recent decades, many bumble bee species have declined due to changes in habitat, climate, and pressures from pathogens, pesticides, and introduced species. The western bumble bee (Bombus occidentalis), once common throughout western North America, is a species of concern and will be considered for listing by the U.S. Fish and Wildlife Service (USFWS) under the Endangered Species Act (ESA). We attempt to improve alignment of data collection and research with USFWS needs to consider redundancy, resiliency, and representation in the upcoming species status assessment. We reviewed existing data and literature on B. occidentalis, highlighting information gaps and priority topics for research. Priorities include increased knowledge of trends, basic information on several life‐history stages, and improved understanding of the relative and interacting effects of stressors on population trends, especially the effects of pathogens, pesticides, climate change, and habitat loss. An understanding of how and where geographic range extent has changed for the two subspecies of B. occidentalis is also needed. We outline data that could be easily collected in other research projects that would increase their utility for understanding range‐wide trends of bumble bees. We modeled the overall trend in occupancy from 1998 to 2018 of Bombus occidentalis within the continental United States using existing data. The probability of local occupancy declined by 93% over 21 yr from 0.81 (95% CRI = 0.43, 0.98) in 1998 to 0.06 (95% CRI = 0.02, 0.16) in 2018. The decline in occupancy varied spatially by landcover and other environmental factors. Detection rates vary in both space and time, but peak detection across the continental United States occurs in mid‐July. We found considerable spatial gaps in recent sampling, with limited sampling in many regions, including most of Alaska, northwestern Canada, and the southwestern United States. We therefore propose a sampling design to address these gaps to best inform the ESA species status assessment through improved assessment of how the spatial distribution of stressors influences occupancy changes. Finally, we request involvement via data sharing, participation in occupancy sampling with repeated visits to distributed survey sites, and complementary research to address priorities outlined in this paper

    The correlation between reading and mathematics ability at age twelve has a substantial genetic component

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    Dissecting how genetic and environmental influences impact on learning is helpful for maximizing numeracy and literacy. Here we show, using twin and genome-wide analysis, that there is a substantial genetic component to children’s ability in reading and mathematics, and estimate that around one half of the observed correlation in these traits is due to shared genetic effects (so-called Generalist Genes). Thus, our results highlight the potential role of the learning environment in contributing to differences in a child’s cognitive abilities at age twelve

    Genome-wide association study identifies a variant in HDAC9 associated with large vessel ischemic stroke

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    Genetic factors have been implicated in stroke risk but few replicated associations have been reported. We conducted a genome-wide association study (GWAS) in ischemic stroke and its subtypes in 3,548 cases and 5,972 controls, all of European ancestry. Replication of potential signals was performed in 5,859 cases and 6,281 controls. We replicated reported associations between variants close to PITX2 and ZFHX3 with cardioembolic stroke, and a 9p21 locus with large vessel stroke. We identified a novel association for a SNP within the histone deacetylase 9(HDAC9) gene on chromosome 7p21.1 which was associated with large vessel stroke including additional replication in a further 735 cases and 28583 controls (rs11984041, combined P = 1.87×10−11, OR=1.42 (95% CI) 1.28-1.57). All four loci exhibit evidence for heterogeneity of effect across the stroke subtypes, with some, and possibly all, affecting risk for only one subtype. This suggests differing genetic architectures for different stroke subtypes

    Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis.

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    Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis

    Temporal trends in the initiation of dialysis among patients with heart failure with or without diabetes: a nationwide study from 2002 to 2016

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    Background The incidence and distribution of acute and chronic dialysis among patients with heart failure (HF), stratified by diabetes, remain uncertain. We hypothesized that with improved survival and rising comorbidities, the demand for dialysis would increase over time. Methods and Results Patients with incident HF, aged 18 to 100 years, between 2002 and 2016, were identified using Danish nationwide registers. Primary outcomes included acute and chronic dialysis initiation, HF‐related hospitalization, and all‐cause mortality. These outcomes were assessed in 2002 to 2006, 2007 to 2011, and 2012 to 2016, stratified by diabetes. We calculated incidence rates (IRs) per 1000 person‐years and hazard ratios (HR) using multivariable Cox regression. Of 115 533 patients with HF, 2734 patients received acute dialysis and 1193 patients received chronic dialysis. The IR was 8.0 per 1000 and 3.5 per 1000 person‐years for acute and chronic dialysis, respectively. Acute dialysis rates increased significantly among patients with diabetes over time, while no significant changes occurred in those without diabetes, chronic dialysis, HF‐related hospitalization, or overall mortality. Diabetes was associated with significantly higher HRs of acute and chronic dialysis, respectively, compared with patients without diabetes (HR, 2.07 [95% CI, 1.80–2.39] and 2.93 [95% CI, 2.40–3.58] in 2002 to 2006; HR, 2.45 [95% CI, 2.14–2.80] and 2.86 [95% CI, 2.32–3.52] in 2007 to 2011; and 2.69 [95% CI, 2.33–3.10] and 3.30 [95% CI, 2.69–4.06] in 2012 to 2016). Conclusions The IR of acute and chronic dialysis remained low compared with HF‐related hospitalizations and mortality. Acute dialysis rates increased significantly over time, contrasting no significant trends in other outcomes. Diabetes exhibited over 2‐fold increased rates of the outcomes. These findings emphasize the importance of continued monitoring and renal care in patients with HF, especially with diabetes, to optimize outcomes and prevent adverse events
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