3,913 research outputs found
Higher Descent Data as a Homotopy Limit
We define the 2-groupoid of descent data assigned to a cosimplicial
2-groupoid and present it as the homotopy limit of the cosimplicial space
gotten after applying the 2-nerve in each cosimplicial degree. This can be
applied also to the case of -groupoids thus providing an analogous
presentation of "descent data" in higher dimensions.Comment: Appeared in JHR
Simulation of gain stability of THGEM gas-avalanche particle detectors
Charging-up processes affecting gain stability in Thick Gas Electron
Multipliers (THGEM) were studied with a dedicated simulation toolkit.
Integrated with Garfield++, it provides an effective platform for systematic
phenomenological studies of charging-up processes in MPGD detectors. We
describe the simulation tool and the fine-tuning of the step-size required for
the algorithm convergence, in relation to physical parameters. Simulation
results of gain stability over time in THGEM detectors are presented, exploring
the role of electrode-thickness and applied voltage on its evolution. The
results show that the total amount of irradiated charge through electrode's
hole needed for reaching gain stabilization is in the range of tens to hundreds
of pC, depending on the detector geometry and operational voltage. These
results are in agreement with experimental observations presented previously
Formal Hecke algebras and algebraic oriented cohomology theories
In the present paper we generalize the construction of the nil Hecke ring of
Kostant-Kumar to the context of an arbitrary algebraic oriented cohomology
theory of Levine-Morel and Panin-Smirnov, e.g. to Chow groups, Grothendieck's
K_0, connective K-theory, elliptic cohomology, and algebraic cobordism. The
resulting object, which we call a formal (affine) Demazure algebra, is
parameterized by a one-dimensional commutative formal group law and has the
following important property: specialization to the additive and multiplicative
periodic formal group laws yields completions of the nil Hecke and the 0-Hecke
rings respectively. We also introduce a deformed version of the formal (affine)
Demazure algebra, which we call a formal (affine) Hecke algebra. We show that
the specialization of the formal (affine) Hecke algebra to the additive and
multiplicative periodic formal group laws gives completions of the degenerate
(affine) Hecke algebra and the usual (affine) Hecke algebra respectively. We
show that all formal affine Demazure algebras (and all formal affine Hecke
algebras) become isomorphic over certain coefficient rings, proving an analogue
of a result of Lusztig.Comment: 28 pages. v2: Some results strengthened and references added. v3:
Minor corrections, section numbering changed to match published version. v4:
Sign errors in Proposition 6.8(d) corrected. This version incorporates an
erratum to the published versio
Cost-effectiveness analysis of 3-D computerized tomography colonography versus optical colonoscopy for imaging symptomatic gastroenterology patients.
BACKGROUND: When symptomatic gastroenterology patients have an indication for colonic imaging, clinicians have a choice between optical colonoscopy (OC) and computerized tomography colonography with three-dimensional reconstruction (3-D CTC). 3-D CTC provides a minimally invasive and rapid evaluation of the entire colon, and it can be an efficient modality for diagnosing symptoms. It allows for a more targeted use of OC, which is associated with a higher risk of major adverse events and higher procedural costs. A case can be made for 3-D CTC as a primary test for colonic imaging followed if necessary by targeted therapeutic OC; however, the relative long-term costs and benefits of introducing 3-D CTC as a first-line investigation are unknown. AIM: The aim of this study was to assess the cost effectiveness of 3-D CTC versus OC for colonic imaging of symptomatic gastroenterology patients in the UK NHS. METHODS: We used a Markov model to follow a cohort of 100,000 symptomatic gastroenterology patients, aged 50 years or older, and estimate the expected lifetime outcomes, life years (LYs) and quality-adjusted life years (QALYs), and costs (£, 2010-2011) associated with 3-D CTC and OC. Sensitivity analyses were performed to assess the robustness of the base-case cost-effectiveness results to variation in input parameters and methodological assumptions. RESULTS: 3D-CTC provided a similar number of LYs (7.737 vs 7.739) and QALYs (7.013 vs 7.018) per individual compared with OC, and it was associated with substantially lower mean costs per patient (£467 vs £583), leading to a positive incremental net benefit. After accounting for the overall uncertainty, the probability of 3-D CTC being cost effective was around 60 %, at typical willingness-to-pay values of £20,000-£30,000 per QALY gained. CONCLUSION: 3-D CTC is a cost-saving and cost-effective option for colonic imaging of symptomatic gastroenterology patients compared with OC
Measuring Cosmic Defect Correlations in Liquid Crystals
From the theory of topological defect formation proposed for the early
universe, the so called Kibble mechanism, it follows that the density
correlation functions of defects and anti-defects in a given system should be
completely determined in terms of a single length scale , the relevant
domain size. Thus, when lengths are expressed in units of , these
distributions should show universal behavior, depending only on the symmetry of
the order parameter, and space dimensions. We have verified this prediction by
analyzing the distributions of defects/anti-defects formed in the
isotropic-nematic phase transition in a thin layer of nematic liquid crystals.
Our experimental results confirm this prediction and are in reasonable
agreement with the results of numerical simulations.Comment: 15 pages, 4 figures, minor changes, few new references adde
Asymmetric function theory
The classical theory of symmetric functions has a central position in
algebraic combinatorics, bridging aspects of representation theory,
combinatorics, and enumerative geometry. More recently, this theory has been
fruitfully extended to the larger ring of quasisymmetric functions, with
corresponding applications. Here, we survey recent work extending this theory
further to general asymmetric polynomials.Comment: 36 pages, 8 figures, 1 table. Written for the proceedings of the
Schubert calculus conference in Guangzhou, Nov. 201
Dark matter search results from the complete exposure of the PICO-60 C3F8 bubble chamber
[EN] Final results are reported from operation of the PICO-60 C3F8 dark matter detector, a bubble chamber filled with 52 kg of C3F8 located in the SNOLAB underground laboratory. The chamber was operated at thermodynamic thresholds as low as 1.2 keV without loss of stability. A new blind 1404-kg-day exposure at 2.45 keV threshold was acquired with approximately the same expected total background rate as the previous 1167-kg-day exposure at 3.3 keV. This increased exposure is enabled in part by a new optical tracking analysis to better identify events near detector walls, permitting a larger fiducial volume. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.2 x 10(-41) cm(2) for a 25 GeV WIMP, improving on previous PICO results for 3-5 GeV WIMPs by an order of magnitude.The PICO Collaboration wishes to thank SNOLAB and its staff for support through underground space, logistical and technical services. SNOLAB operations are supported by the Canada Foundation for Innovation and the Province of Ontario Ministry of Research and Innovation, with underground access provided by Vale at the Creighton mine site. We are grateful to Genevieve Belanger and Alexander Pukhov of the Universit e de Savoie for their useful correspondence regarding the interpretation of PICO results. We wish to acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation (CFI) for funding. We acknowledge the support from the National Science Foundation (NSF) (Grants No. 0919526, No. 1506337, No. 1242637, No. 1205987, and No. 1806722). We acknowledge that this work is supported by the U.S. Department of Energy (DOE) Office of Science, Office of High Energy Physics (under Award No. DE-SC-0012161), by the DOE Office of Science Graduate Student Research (SCGSR) award, by DGAPA-UNAM (PAPIIT No. IA100118) and Consejo Nacional de Ciencia y Tecnologia (CONACyT, Mexico, Grants No. 252167 and No. A1-S-8960), by the Department of Atomic Energy (DAE), Government of India, under the Centre for AstroParticle Physics II project (CAPP-II) at the Saha Institute of Nuclear Physics (SINP), European Regional Development FundProject "Engineering applications of microworld physics" (No. CZ. 02.1.01/0.0/0.0/16_019/0000766), and the Spanish (Ministry of Science, Innovation and Universities) Ministerio de Ciencia, Innovacion y Universidades (Red Consolider MultiDark, FPA2017-90566-REDC). This work is partially supported by the Kavli Institute for Cosmological Physics at the University of Chicago through NSF Grant No. 1125897, and an endowment from the Kavli Foundation and its founder Fred Kavli. We also wish to acknowledge the support from Fermi National Accelerator Laboratory under Contract No. DE-AC02-07CH11359, and from Pacific Northwest National Laboratory, which is operated by Battelle for the U.S. Department of Energy under Contract No. DE-AC05-76RL01830. We also thank Compute Canada (www.computecanada.ca) and the Centre for Advanced Computing, ACENET, Calcul Quebec, Compute Ontario and WestGrid for computational support.Amole, C.; Ardid Ramírez, M.; Arnquist, I.; Asner, DM.; Baxter, D.; Behnke, E.; Bressler, M.... (2019). Dark matter search results from the complete exposure of the PICO-60 C3F8 bubble chamber. Physical Review D: covering particles, fields, gravitation, and cosmology. 100(2):1-9. https://doi.org/10.1103/PhysRevD.100.022001191002Olive, K. A. (2014). Review of Particle Physics. Chinese Physics C, 38(9), 090001. doi:10.1088/1674-1137/38/9/090001Komatsu, E., Dunkley, J., Nolta, M. R., Bennett, C. L., Gold, B., Hinshaw, G., … Wright, E. L. (2009). FIVE-YEAR
WILKINSON MICROWAVE ANISOTROPY PROBE
OBSERVATIONS: COSMOLOGICAL INTERPRETATION. The Astrophysical Journal Supplement Series, 180(2), 330-376. doi:10.1088/0067-0049/180/2/330Jungman, G., Kamionkowski, M., & Griest, K. (1996). Supersymmetric dark matter. Physics Reports, 267(5-6), 195-373. doi:10.1016/0370-1573(95)00058-5Goodman, M. W., & Witten, E. (1985). Detectability of certain dark-matter candidates. Physical Review D, 31(12), 3059-3063. doi:10.1103/physrevd.31.3059Amole, C., Ardid, M., Arnquist, I. J., Asner, D. M., Baxter, D., Behnke, E., … Campion, P. (2017). Dark Matter Search Results from the
PICO−60 C3F8
Bubble Chamber. Physical Review Letters, 118(25). doi:10.1103/physrevlett.118.251301Amole, C., Ardid, M., Asner, D. M., Baxter, D., Behnke, E., Bhattacharjee, P., … Broemmelsiek, D. (2016). Dark matter search results from the PICO-60CF3Ibubble chamber. Physical Review D, 93(5). doi:10.1103/physrevd.93.052014McLure, I. A., Soares, V. A. M., & Edmonds, B. (1982). Surface tension of perfluoropropane, perfluoro-n-butane, perfluoro-n-hexane, perfluoro-octane, perfluorotributylamine and n-pentane. Application of the principle of corresponding states to the surface tension of perfluoroalkanes. Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, 78(7), 2251. doi:10.1039/f19827802251Baxter, D., Chen, C. J., Crisler, M., Cwiok, T., Dahl, C. E., Grimsted, A., … Zhang, J. (2017). First Demonstration of a Scintillating Xenon Bubble Chamber for Detecting Dark Matter and Coherent Elastic Neutrino-Nucleus Scattering. 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Physical Review Letters, 121(7). doi:10.1103/physrevlett.121.071801Cowan, G., Cranmer, K., Gross, E., & Vitells, O. (2011). Asymptotic formulae for likelihood-based tests of new physics. The European Physical Journal C, 71(2). doi:10.1140/epjc/s10052-011-1554-0Lewin, J. D., & Smith, P. F. (1996). Review of mathematics, numerical factors, and corrections for dark matter experiments based on elastic nuclear recoil. Astroparticle Physics, 6(1), 87-112. doi:10.1016/s0927-6505(96)00047-3Fitzpatrick, A. L., Haxton, W., Katz, E., Lubbers, N., & Xu, Y. (2013). The effective field theory of dark matter direct detection. Journal of Cosmology and Astroparticle Physics, 2013(02), 004-004. doi:10.1088/1475-7516/2013/02/004Anand, N., Fitzpatrick, A. L., & Haxton, W. C. (2014). Weakly interacting massive particle-nucleus elastic scattering response. Physical Review C, 89(6). doi:10.1103/physrevc.89.065501Gresham, M. I., & Zurek, K. M. (2014). Effect of nuclear response functions in dark matter direct detection. Physical Review D, 89(12). doi:10.1103/physrevd.89.123521Gluscevic, V., Gresham, M. I., McDermott, S. D., Peter, A. H. G., & Zurek, K. M. (2015). Identifying the theory of dark matter with direct detection. Journal of Cosmology and Astroparticle Physics, 2015(12), 057-057. doi:10.1088/1475-7516/2015/12/057Amole, C., Ardid, M., Arnquist, I. J., Asner, D. M., Baxter, D., Behnke, E., … Brice, S. J. (2016). Improved dark matter search results from PICO-2L Run 2. Physical Review D, 93(6). doi:10.1103/physrevd.93.061101Behnke, E., Besnier, M., Bhattacharjee, P., Dai, X., Das, M., Davour, A., … Zacek, V. (2017). Final results of the PICASSO dark matter search experiment. Astroparticle Physics, 90, 85-92. doi:10.1016/j.astropartphys.2017.02.005Felizardo, M., Girard, T. A., Morlat, T., Fernandes, A. C., Ramos, A. R., Marques, J. G., … Marques, R. (2014). The SIMPLE Phase II dark matter search. Physical Review D, 89(7). doi:10.1103/physrevd.89.072013Aprile, E., Aalbers, J., Agostini, F., Alfonsi, M., Althueser, L., Amaro, F. D., … Baudis, L. (2019). Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T. Physical Review Letters, 122(14). doi:10.1103/physrevlett.122.141301Fu, C., Cui, X., Zhou, X., Chen, X., Chen, Y., … Fang, D. (2017). Spin-Dependent Weakly-Interacting-Massive-Particle–Nucleon Cross Section Limits from First Data of PandaX-II Experiment. Physical Review Letters, 118(7). doi:10.1103/physrevlett.118.071301Aartsen, M. G., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., … Ansseau, I. (2017). Search for annihilating dark matter in the Sun with 3 years of IceCube data. The European Physical Journal C, 77(3). doi:10.1140/epjc/s10052-017-4689-9Tanaka, T., Abe, K., Hayato, Y., Iida, T., Kameda, J., Koshio, Y., … Nakahata, M. (2011). AN INDIRECT SEARCH FOR WEAKLY INTERACTING MASSIVE PARTICLES IN THE SUN USING 3109.6 DAYS OF UPWARD-GOING MUONS IN SUPER-KAMIOKANDE. The Astrophysical Journal, 742(2), 78. doi:10.1088/0004-637x/742/2/78Choi, K., Abe, K., Haga, Y., Hayato, Y., Iyogi, K., Kameda, J., … Nakahata, M. (2015). Search for Neutrinos from Annihilation of Captured Low-Mass Dark Matter Particles in the Sun by Super-Kamiokande. Physical Review Letters, 114(14). doi:10.1103/physrevlett.114.141301Akerib, D. S., Araújo, H. M., Bai, X., Bailey, A. J., Balajthy, J., Beltrame, P., … Boulton, E. M. (2016). Results on the Spin-Dependent Scattering of Weakly Interacting Massive Particles on Nucleons from the Run 3 Data of the LUX Experiment. Physical Review Letters, 116(16). doi:10.1103/physrevlett.116.161302Adrián-Martínez, S., Albert, A., André, M., Anton, G., Ardid, M., Aubert, J.-J., … Basa, S. (2016). Limits on dark matter annihilation in the sun using the ANTARES neutrino telescope. Physics Letters B, 759, 69-74. doi:10.1016/j.physletb.2016.05.019Adrián-Martínez, S., Albert, A., André, M., Anton, G., Ardid, M., Aubert, J.-J., … Basa, S. (2016). A search for Secluded Dark Matter in the Sun with the ANTARES neutrino telescope. Journal of Cosmology and Astroparticle Physics, 2016(05), 016-016. doi:10.1088/1475-7516/2016/05/016Agnes, P., Albuquerque, I. F. M., Alexander, T., Alton, A. K., Araujo, G. R., Asner, D. M., … Batignani, G. (2018). Low-Mass Dark Matter Search with the DarkSide-50 Experiment. Physical Review Letters, 121(8). doi:10.1103/physrevlett.121.081307Aprile, E., Aalbers, J., Agostini, F., Alfonsi, M., Althueser, L., Amaro, F. D., … Bauermeister, B. (2018). Dark Matter Search Results from a One Ton-Year Exposure of XENON1T. Physical Review Letters, 121(11). doi:10.1103/physrevlett.121.111302Akerib, D. S., Alsum, S., Araújo, H. M., Bai, X., Bailey, A. J., Balajthy, J., … Biesiadzinski, T. P. (2017). Results from a Search for Dark Matter in the Complete LUX Exposure. Physical Review Letters, 118(2). doi:10.1103/physrevlett.118.021303Tan, A., Xiao, M., Cui, X., Chen, X., Chen, Y., Fang, D., … Gong, H. (2016). Dark Matter Results from First 98.7 Days of Data from the PandaX-II Experiment. Physical Review Letters, 117(12). doi:10.1103/physrevlett.117.121303Agnese, R., Anderson, A. J., Aramaki, T., Asai, M., Baker, W., Balakishiyeva, D., … Billard, J. (2016). New Results from the Search for Low-Mass Weakly Interacting Massive Particles with the CDMS Low Ionization Threshold Experiment. Physical Review Letters, 116(7). doi:10.1103/physrevlett.116.071301Angloher, G., Bento, A., Bucci, C., Canonica, L., Defay, X., Erb, A., … Zöller, A. (2016). Results on light dark matter particles with a low-threshold CRESST-II detector. The European Physical Journal C, 76(1). doi:10.1140/epjc/s10052-016-3877-3Aprile, E., Aalbers, J., Agostini, F., Alfonsi, M., Amaro, F. D., Anthony, M., … Bauermeister, B. (2016). XENON100 dark matter results from a combination of 477 live days. Physical Review D, 94(12). doi:10.1103/physrevd.94.122001Agnese, R., Anderson, A. J., Asai, M., Balakishiyeva, D., Basu Thakur, R., Bauer, D. A., … Bowles, M. A. (2014). Search for Low-Mass Weakly Interacting Massive Particles with SuperCDMS. Physical Review Letters, 112(24). doi:10.1103/physrevlett.112.241302Agnese, R., Anderson, A. J., Asai, M., Balakishiyeva, D., Barker, D., Basu Thakur, R., … Bowles, M. A. (2015). Improved WIMP-search reach of the CDMS II germanium data. Physical Review D, 92(7). doi:10.1103/physrevd.92.072003Hehn, L., Armengaud, E., Arnaud, Q., Augier, C., Benoît, A., Bergé, L., … Yakushev, E. (2016). Improved EDELWEISS-III sensitivity for low-mass WIMPs using a profile likelihood approach. The European Physical Journal C, 76(10). doi:10.1140/epjc/s10052-016-4388-
Prevalence and Predictors of Herbal Medicine Use Among Adults in the United States
Objective: To describe the prevalence of herbal medicine use among US adults and to assess factors associated with and predictors of herbal use. Design: The data for herbal products use were collected from the 2015 National Consumer Survey on the Medication Experience and Pharmacists’ Roles. Chi-square test was used to analyz factors associated with herbal use, and predictors of herbal use were assessed with logistic regression analysis. Results: Factors associated with herbal supplement use include age older than 70, having a higher than high school education, using prescription medications or over-thecounter (OTC) medications, and using a mail-order pharmacy.” All Disease state associated significantly with herbal use. Approximately thirty-eight percent of those who used herbals used prescription medications and 42% of those who used herbals also used an OTC medication. The most frequent conditions associated with herbal supplement use were a stroke (48.7%), cancer (43.1%), and arthritis (43.0%). Among herbal product users, factors that predicted use included having higher than school education, using OTC medications, using mail-order pharmacy, stroke, obesity, arthritis, and breathing problems. Conclusions: More than one-third of respondents reported using herbal supplements. Older age and higher education were associated with a higher use of herbal supplements. People with chronic diseases are more likely to use herbal medicines than others. OTC drug users and patients with stroke are more likely to use herbal medicines than others
Midlife Determinants of Healthy Cardiovascular aging: the atherosclerosis Risk in Communities (Aric) Study
BACKGROUND AND AIMS: Risk factor cutoffs are derived from associations with clinical cardiovascular disease (CVD), but how these risk factors associate with preserved cardiovascular health into old age is not well studied. We investigated midlife determinants of healthy versus nonhealthy cardiovascular aging in the Atherosclerosis Risk in Communities (ARIC) study.
METHODS: ARIC participants were categorized by cardiovascular status in older age (mean age 75.8 ± 5.3 years, range 66-90): healthy, subclinical disease (assessed by biomarkers and left ventricular function), clinical CVD (coronary heart disease, stroke, or heart failure), or prior death. We examined associations of midlife (mean age 52.1 ± 5.1 years) systolic and diastolic blood pressure (SBP, DBP), low-density lipoprotein cholesterol (LDL-C), triglycerides, hemoglobin A1c (HbA1c), and body mass index (BMI) with cardiovascular status in older age using multinomial logistic regression analyses.
RESULTS: Compared with healthy status, odds for subclinical disease (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.09-1.55) and clinical CVD (OR 1.87, 95% CI 1.53-2.29) at older age increased starting with midlife SBP 120-129 mmHg, whereas odds for death increased starting with SBP 110-119 mmHg (OR 1.29, 95% CI 1.10-1.52); findings were similar for DBP. Odds for subclinical disease increased for HbA1c ≥ 6.5% and BMI starting at 30-/m
CONCLUSIONS: More-stringent levels of modifiable risk factors in midlife beyond current clinical practice and guidelines were associated with preserved cardiovascular health in older age
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