24,240 research outputs found

    Critical exponents for 3D O(n)-symmetric model with n > 3

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    Critical exponents for the 3D O(n)-symmetric model with n > 3 are estimated on the base of six-loop renormalization-group (RG) expansions. A simple Pade-Borel technique is used for the resummation of the RG series and the Pade approximants [L/1] are shown to give rather good numerical results for all calculated quantities. For large n, the fixed point location g_c and the critical exponents are also determined directly from six-loop expansions without addressing the resummation procedure. An analysis of the numbers obtained shows that resummation becomes unnecessary when n exceeds 28 provided an accuracy of about 0.01 is adopted as satisfactory for g_c and critical exponents. Further, results of the calculations performed are used to estimate the numerical accuracy of the 1/n-expansion. The same value n = 28 is shown to play the role of the lower boundary of the domain where this approximation provides high-precision estimates for the critical exponents.Comment: 10 pages, TeX, no figure

    A MMT/Hectospec Redshift Survey of 24 Micron Sources in the Spitzer First Look Survey

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    We present a spectroscopic survey using the MMT/Hectospec fiber spectrograph of 24 micron sources selected with the Spitzer Space Telescope in the Spitzer First Look Survey. We report 1296 new redshifts for 24 micron sources, including 599 with f(24micron) > 1 mJy. Combined with 291 additional redshifts for sources from the Sloan Digital Sky Survey (SDSS), our observing program was highly efficient and is ~90% complete for i' 1 mJy, and is 35% complete for i' < 20.5 mag and 0.3 mJy < f(24micron) < 1 mJy. Our Hectospec survey includes 1078 and 168 objects spectroscopically classified as galaxies and QSOs, respectively. Combining the Hectospec and SDSS samples, we find 24 micron-selected galaxies to z < 0.98 and QSOs to z < 3.6, with mean redshifts of = 0.27 and =1.1. As part of this publication, we include the redshift catalogs and the reduced spectra; these are also available online (http://mips.as.arizona.edu/~papovich/fls) and through the NASA/IPAC Infrared Science Archive (http://irsa.ipac.caltech.edu).Comment: Accepted for publication in the Astronomical Journal, AASTEX format, 23 pages, 7 figures (some in color). This replacement is the accepted version, and includes minor changes from previous version. Data tables and spectra available at http://mips.as.arizona.edu/~papovich/fls or at http://irsa.ipac.caltech.ed

    Toward high-precision values of the self energy of non-S states in hydrogen and hydrogen-like ions

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    The method and status of a study to provide numerical, high-precision values of the self-energy level shift in hydrogen and hydrogen-like ions is described. Graphs of the self energy in hydrogen-like ions with nuclear charge number between 20 and 110 are given for a large number of states. The self-energy is the largest contribution of Quantum Electrodynamics (QED) to the energy levels of these atomic systems. These results greatly expand the number of levels for which the self energy is known with a controlled and high precision. Applications include the adjustment of the Rydberg constant and atomic calculations that take into account QED effects.Comment: Minor changes since previous versio

    Vacuum Stability Bound on Extended GMSB Models

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    Extensions of GMSB models were explored to explain the recent reports of the Higgs boson mass around 124-126 GeV. Some models predict a large mu term, which can spoil the vacuum stability of the universe. We study two GMSB extensions: i) the model with a large trilinear coupling of the top squark, and ii) that with extra vector-like matters. In both models, the vacuum stability condition provides upper bounds on the gluino mass if combined with the muon g-2. The whole parameter region is expected to be covered by LHC at sqrt{s} = 14 TeV. The analysis is also applied to the mSUGRA models with the vector-like matters.Comment: 22 pages, 4 figure

    Probing EWSB Naturalness in Unified SUSY Models with Dark Matter

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    We have studied Electroweak Symmetry Breaking (EWSB) fine-tuning in the context of two unified Supersymmetry scenarios: the Constrained Minimal Supersymmetric Model (CMSSM) and models with Non-Universal Higgs Masses (NUHM), in light of current and upcoming direct detection dark matter experiments. We consider both those models that satisfy a one-sided bound on the relic density of neutralinos, Ωχh2<0.12\Omega_{\chi} h^2 < 0.12, and also the subset that satisfy the two-sided bound in which the relic density is within the 2 sigma best fit of WMAP7 + BAO + H0 data. We find that current direct detection searches for dark matter probe the least fine-tuned regions of parameter-space, or equivalently those of lowest Higgs mass parameter ÎŒ\mu, and will tend to probe progressively more and more fine-tuned models, though the trend is more pronounced in the CMSSM than in the NUHM. Additionally, we examine several subsets of model points, categorized by common mass hierarchies; M_{\chi_0} \sim M_{\chi^\pm}, M_{\chi_0} \sim M_{\stau}, M_{\chi_0} \sim M_{\stop_1}, the light and heavy Higgs poles, and any additional models classified as "other"; the relevance of these mass hierarchies is their connection to the preferred neutralino annihilation channel that determines the relic abundance. For each of these subsets of models we investigated the degree of fine-tuning and discoverability in current and next generation direct detection experiments.Comment: 26 pages, 10 figures. v2: references added. v3: matches published versio

    Mortality of Patients with Hematological Malignancy after Admission to the Intensive Care Unit

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    Background: The admission of patients with malignancies to an intensive care unit (ICU) still remains a matter of substantial controversy. The identification of factors that potentially influence the patient outcome can help ICU professionals make appropriate decisions. Patients and Methods: 90 adult patients with hematological malignancy (leukemia 47.8%, high-grade lymphoma 50%) admitted to the ICU were analyzed retrospectively in this single-center study considering numerous variables with regard to their influence on ICU and day-100 mortality. Results: The median simplified acute physiology score (SAPS) II at ICU admission was 55 (ICU survivors 47 vs. 60.5 for non-survivors). The overall ICU mortality rate was 45.6%. With multivariate regression analysis, patients admitted with sepsis and acute respiratory failure had a significantly increased ICU mortality (sepsis odds ratio (OR) 9.12, 95% confidence interval (CI) 1.1-99.7, p = 0.04; respiratory failure OR 13.72, 95% CI 1.39-136.15, p = 0.025). Additional factors associated with an increased mortality were: high doses of catecholamines (ICU: OR 7.37, p = 0.005; day 100: hazard ratio (HR) 2.96, p < 0.0001), renal replacement therapy (day 100: HR 1.93, p = 0.026), and high SAPS II (ICU: HR 1.05, p = 0.038; day 100: HR 1.2, p = 0.027). Conclusion: The decision for or against ICU admission of patients with hematological diseases should become increasingly independent of the underlying malignant disease

    Renormalization Group Functions for Two-Dimensional Phase Transitions: To the Problem of Singular Contributions

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    According to the available publications, the field theoretical renormalization group (RG) approach in the two-dimensional case gives the critical exponents that differ from the known exact values. This fact was attempted to explain by the existence of nonanalytic contributions in the RG functions. The situation is analysed in this work using a new algorithm for summing divergent series that makes it possible to analyse dependence of the results for the critical exponents on the expansion coefficients for RG functions. It has been shown that the exact values of all the exponents can be obtained with a reasonable form of the coefficient functions. These functions have small nonmonotonities or inflections, which are poorly reproduced in natural interpolations. It is not necessary to assume the existence of singular contributions in RG functions.Comment: PDF, 11 page

    A hybrid constructed wetland for organic-material and nutrient removal from sewage: Process performance and multi-kinetic models

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    © 2018 Elsevier Ltd A pilot-scale hybrid constructed wetland with vertical flow and horizontal flow in series was constructed and used to investigate organic material and nutrient removal rate constants for wastewater treatment and establish a practical predictive model for use. For this purpose, the performance of multiple parameters was statistically evaluated during the process and predictive models were suggested. The measurement of the kinetic rate constant was based on the use of the first-order derivation and Monod kinetic derivation (Monod) paired with a plug flow reactor (PFR) and a continuously stirred tank reactor (CSTR). Both the Lindeman, Merenda, and Gold (LMG) analysis and Bayesian model averaging (BMA) method were employed for identifying the relative importance of variables and their optimal multiple regression (MR). The results showed that the first-order–PFR (M2) model did not fit the data (P > 0.05, and R2 0.5). The pollutant removal rates in the case of M1 were 0.19 m/d (CODCr) and those for M3 were 25.2 g/m2∙d for CODCr and 2.63 g/m2∙d for NH4-N. By applying a multi-variable linear regression method, the optimal empirical models were established for predicting the final effluent concentration of five days' biochemical oxygen demand (BOD5) and NH4-N. In general, the hydraulic loading rate was considered an important variable having a high value of relative importance, which appeared in all the optimal predictive models

    Assessment of potential cardiotoxic side effects of mitoxantrone in patients with multiple sclerosis

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    Previous studies showed that mitoxantrone can reduce disability progression in patients with multiple sclerosis (MS). There is, however, concern that it may cause irreversible cardiomyopathy with reduced left ventricular (LV) ejection fraction (EF) and congestive heart failure. The aim of this prospective study was to investigate cardiac side effects of mitoxantrone by repetitive cardiac monitoring in MS patients. The treatment protocol called for ten courses of a combined mitoxantrone (10 mg/m(2) body surface) and methylprednisolone therapy. Before each course, a transthoracic echocardiogram was performed to determine the LV end-diastolic diameter, the end-systolic diameter and the fractional shortening; the LV-EF was calculated. Seventy-three patients participated (32 males; age 48 +/- 12 years, range 20-75 years; 25 with primary progressive, 47 with secondary progressive and 1 with relapsing-remitting MS) who received at least four courses of mitoxantrone. Three of the 73 patients were excluded during the study (2 patients discontinued therapy; 1 patient with a previous history of ischemic heart disease developed atrial fibrillation after the second course of mitoxantrone). The mean cumulative dose of mitoxantrone was 114.0 +/- 33.8 mg. The mean follow-up time was 23.4 months (range 10-57 months). So far, there has been no significant change in any of the determined parameters (end-diastolic diameter, end-systolic diameter, fractional shortening, EF) over time during all follow-up investigations. Mitoxantrone did not cause signs of congestive heart failure in any of the patients. Further cardiac monitoring is, however, needed to determine the safety of mitoxantrone after longer follow-up times and at higher cumulative doses. Copyright (C) 2005 S. Karger AG, Basel
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