1,346 research outputs found

    Autonomic Nerve Activity and Blood Pressure in Ambulatory Dogs

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    Background The relationship between cardiac autonomic nerve activity and blood pressure (BP) changes in ambulatory dogs is unclear. Objective To test the hypotheses that simultaneous termination of stellate ganglion nerve activity (SGNA) and vagal nerve activity (VNA) predisposes to spontaneous orthostatic hypotension and that specific β2 adrenoceptor blockade prevents the hypotensive episodes. Methods We used a radiotransmitter to record SGNA, VNA and blood pressure (BP) in 8 ambulatory dogs. Video imaging was used to document postural changes. Results Out of these 8 dogs, 5 showed simultaneous sympathovagal discharges in which the minute by minute integrated SGNA correlated with integrated VNA in a linear pattern (“Group 1”). In these dogs abrupt termination of simultaneous SGNA-VNA at the time of postural changes (as documented by video imaging) was followed by abrupt (>20 mmHg over 4 beats) drops in BP. Dogs without simultaneous on/off firing (“Group 2”) did not have drastic drops in pressure. ICI 118,551 (ICI, a specific β2-blocker) infused at 3.1 µg/kg/hr for 7 days significantly increased BP from 126 (95% confidence interval, CI: 118 to 133) mmHg to 133 (95% CI 125 to141) mmHg (p=0.0001). The duration of hypotension (mean systolic BP < 100 mmHg) during baseline accounted for 7.1% of the recording. The percentage was reduced by ICI to 1.3% (p = 0.01). Conclusions Abrupt simultaneous termination of SGNA-VNA was observed at the time of orthostatic hypotension in ambulatory dogs. Selective β2 adrenoceptor blockade increased BP and reduced the duration of hypotension in this model

    The fundamental pro-groupoid of an affine 2-scheme

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    A natural question in the theory of Tannakian categories is: What if you don't remember \Forget? Working over an arbitrary commutative ring RR, we prove that an answer to this question is given by the functor represented by the \'etale fundamental groupoid \pi_1(\spec(R)), i.e.\ the separable absolute Galois group of RR when it is a field. This gives a new definition for \'etale \pi_1(\spec(R)) in terms of the category of RR-modules rather than the category of \'etale covers. More generally, we introduce a new notion of "commutative 2-ring" that includes both Grothendieck topoi and symmetric monoidal categories of modules, and define a notion of π1\pi_1 for the corresponding "affine 2-schemes." These results help to simplify and clarify some of the peculiarities of the \'etale fundamental group. For example, \'etale fundamental groups are not "true" groups but only profinite groups, and one cannot hope to recover more: the "Tannakian" functor represented by the \'etale fundamental group of a scheme preserves finite products but not all products.Comment: 46 pages + bibliography. Diagrams drawn in Tik

    The Eco-Epidemiology of Pacific Coast Tick Fever in California

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    Rickettsia philipii (type strain “Rickettsia 364D”), the etiologic agent of Pacific Coast tick fever (PCTF), is transmitted to people by the Pacific Coast tick, Dermacentor occidentalis. Following the first confirmed human case of PCTF in 2008, 13 additional human cases have been reported in California, more than half of which were pediatric cases. The most common features of PCTF are the presence of at least one necrotic lesion known as an eschar (100%), fever (85%), and headache (79%); four case-patients required hospitalization and four had multiple eschars. Findings presented here implicate the nymphal or larval stages of D. occidentalis as the primary vectors of R. philipii to people. Peak transmission risk from ticks to people occurs in late summer. Rickettsia philipii DNA was detected in D. occidentalis ticks from 15 of 37 California counties. Similarly, non-pathogenic Rickettsia rhipicephali DNA was detected in D. occidentalis in 29 of 38 counties with an average prevalence of 12.0% in adult ticks. In total, 5,601 ticks tested from 2009 through 2015 yielded an overall R. philipii infection prevalence of 2.1% in adults, 0.9% in nymphs and a minimum infection prevalence of 0.4% in larval pools. Although most human cases of PCTF have been reported from northern California, acarological surveillance suggests that R. philipii may occur throughout the distribution range of D. occidentalis

    A Threat Assessment and Security Analysis of the Three Sports Facilities of Indiana University-Purdue University, Indianapolis NCAA Softball Fields, Carroll Stadium, and the IU Natatorium

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    This research report provides a security assessment of the Softball Fields, Carroll Stadium, and the Natatorium Complex at Indiana University-Purdue University Indianapolis (IUPUI). The purpose of this report is to prevent and mitigate harm to visitors and these facilities which resulting from human-made or natural disasters. Research is guided by the hypothesis that these facilities- due to their respective importance, locations, and attendance patterns are in harm’s way; and that certain strategies of prevention, protection, and mitigation coupled with effective preparedness, response, and recovery can lessen risk, improve security and provide A THREAT ASSESSMENT AND SECURITY ANALYSIS 5 added resilience. Further, “harm’s way” is considered to be either a natural disaster or a human-made disaster, accident, active provocation, or act of terrorism. Methods of analysis include applied research; predominantly utilizing qualitative data with some quantitative investigation. Results of this assessment illustrate that these venues possess numerous vulnerabilities to both natural and human-made threats that if exposed, could result in serious consequences. The two most likely natural hazards identified include straight-line winds and tornadoes. Further, the most likely human threats to these facilities arise from a potential terrorist vehicle attack (TVA) and an active shooter. This project also identifies a specific need for additional planning to prevent an IED or VBIED attack on the Natatorium. Common themes from the attached three case studies reveal that given theses vulnerabilities, the following safety and security adjustments are recommended: Surveillance equipment Metal detectors Security bollards or other temporary barriers Evacuation routes and shelter in place plans Special event security procedures Weather related technology and protocols Staff training for emergency situation

    Status of Muon Collider Research and Development and Future Plans

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    The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides continued work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (CoM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay (π→μνμ\pi \to \mu \nu_{\mu}) channel, muon cooling, acceleration, storage in a collider ring and the collider detector. We also present theoretical and experimental R & D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the R & D since the Feasibility Study of Muon Colliders presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A. Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics (Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].Comment: 95 pages, 75 figures. Submitted to Physical Review Special Topics, Accelerators and Beam

    Scrambling for access: availability, accessibility, acceptability and quality of healthcare for lesbian, gay, bisexual and transgender people in South Africa

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    BACKGROUND: Sexual orientation and gender identity are social determinants of health for people identifying as lesbian, gay, bisexual and transgender (LGBT), and health disparities among sexual and gender minority populations are increasingly well understood. Although the South African constitution guarantees sexual and gender minority people the right to non-discrimination and the right to access to healthcare, homo- and transphobia in society abound. Little is known about LGBT people's healthcare experiences in South Africa, but anecdotal evidence suggests significant barriers to accessing care. Using the framework of the UN International Covenant on Economic, Social and Cultural Rights General Comment 14, this study analyses the experiences of LGBT health service users using South African public sector healthcare, including access to HIV counselling, testing and treatment. METHODS: A qualitative study comprised of 16 semi-structured interviews and two focus group discussions with LGBT health service users, and 14 individual interviews with representatives of LGBT organisations. Data were thematically analysed within the framework of the UN International Covenant on Economic, Social and Cultural Rights General Comment 14, focusing on availability, accessibility, acceptability and quality of care. RESULTS: All interviewees reported experiences of discrimination by healthcare providers based on their sexual orientation and/or gender identity. Participants recounted violations of all four elements of the UN General Comment 14: 1) Availability: Lack of public health facilities and services, both for general and LGBT-specific concerns; 2) Accessibility: Healthcare providers' refusal to provide care to LGBT patients; 3) Acceptability: Articulation of moral judgment and disapproval of LGBT patients' identity, and forced subjection of patients to religious practices; 4) Quality: Lack of knowledge about LGBT identities and health needs, leading to poor-quality care. Participants had delayed or avoided seeking healthcare in the past, and none had sought out accountability or complaint mechanisms within the health system. CONCLUSION: Sexual orientation and gender identity are important categories of analysis for health equity, and lead to disparities in all four dimensions of healthcare access as defined by General Comment 14. Discriminatory and prejudicial attitudes by healthcare providers, combined with a lack of competency and knowledge are key reasons for these disparities in South Africa

    Investigating associations between blood metabolites, later life brain imaging measures, and genetic risk for Alzheimer’s disease

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    BACKGROUND: Identifying blood-based signatures of brain health and preclinical pathology may offer insights into early disease mechanisms and highlight avenues for intervention. Here, we systematically profiled associations between blood metabolites and whole-brain volume, hippocampal volume, and amyloid-β status among participants of Insight 46-the neuroscience sub-study of the National Survey of Health and Development (NSHD). We additionally explored whether key metabolites were associated with polygenic risk for Alzheimer's disease (AD). METHODS: Following quality control, levels of 1019 metabolites-detected with liquid chromatography-mass spectrometry-were available for 1740 participants at age 60-64. Metabolite data were subsequently clustered into modules of co-expressed metabolites using weighted coexpression network analysis. Accompanying MRI and amyloid-PET imaging data were present for 437 participants (age 69-71). Regression analyses tested relationships between metabolite measures-modules and hub metabolites-and imaging outcomes. Hub metabolites were defined as metabolites that were highly connected within significant (pFDR < 0.05) modules or were identified as a hub in a previous analysis on cognitive function in the same cohort. Regression models included adjustments for age, sex, APOE genotype, lipid medication use, childhood cognitive ability, and social factors. Finally, associations were tested between AD polygenic risk scores (PRS), including and excluding the APOE region, and metabolites and modules that significantly associated (pFDR < 0.05) with an imaging outcome (N = 1638). RESULTS: In the fully adjusted model, three lipid modules were associated with a brain volume measure (pFDR < 0.05): one enriched in sphingolipids (hippocampal volume: ß = 0.14, 95% CI = [0.055,0.23]), one in several fatty acid pathways (whole-brain volume: ß =  - 0.072, 95%CI = [- 0.12, - 0.026]), and another in diacylglycerols and phosphatidylethanolamines (whole-brain volume: ß =  - 0.066, 95% CI = [- 0.11, - 0.020]). Twenty-two hub metabolites were associated (pFDR < 0.05) with an imaging outcome (whole-brain volume: 22; hippocampal volume: 4). Some nominal associations were reported for amyloid-β, and with an AD PRS in our genetic analysis, but none survived multiple testing correction. CONCLUSIONS: Our findings highlight key metabolites, with functions in membrane integrity and cell signalling, that associated with structural brain measures in later life. Future research should focus on replicating this work and interrogating causality
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