3,131 research outputs found

    Impact of nanosecond proton beam processing on nanoblocks of copper

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    X-ray studies in conjunction with the method of recoil nuclei and electron microscopy of irradiated plates polycrystalline Cu by nanosecond high power density proton beams (E=120 keV; I=80 A/cm{2}, t=50 ns) showed nano block nature of the formation of structure in the surface layer target and condensed-formed film

    Fluctuations of the number of participants and binary collisions in AA interactions at fixed centrality in the Glauber approach

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    In the framework of the classical Glauber approach, the analytical expressions for the variance of the number of wounded nucleons and binary collisions in AA interactions at a given centrality are presented. Along with the optical approximation term, they contain additional contact terms arising only in the case of nucleus-nucleus collisions. The magnitude of the additional contributions, e.g., for PbPb collisions at SPS energies, is larger than the contribution of the optical approximation at some values of the impact parameter. The sum of the additional contributions is in good agreement with the results of independent Monte Carlo simulations of this process. Due to these additional terms, the variance of the total number of participants for peripheral PbPb collisions and the variance of the number of collisions at all values of the impact parameter exceed several multiples of the Poisson variances. The correlator between the numbers of participants in colliding nuclei at fixed centrality is also analytically calculated.Comment: updated version; as published by Phys. Rev.

    Probing the isospin dependent mean field and nucleon nucleon cross section in the medium by the nucleon emissions

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    We study the isospin effects of the mean field and two-body collision on the nucleon emissions at the intermediate energy heavy ion collisions by using an isospin dependent transport theory. The calculated results show that the nucleon emission number NnN_{n} depends sensitively the isospin effect of nucleon nucleon cross section and weakly on the isospin dependent mean field for neutron-poor system in higher beam energy region . In particular, the correlation between the medium correction of two-body collision and the momentum dependent interaction enhances the dependence of nucleon emission number NnN_{n} on the isospin effect of nucleon nucleon cross section. On the contrary, the ratio of the neutron proton ratio of the gas phase to the neutron proton ratio of the liquid phase, i.e., the degree of isospin fractionation b/b_{b}/_{b} depends sensitively on the isospin dependent mean field and weakly on the isospin effect of two-body collision for neutron-rich system in the lower beam energy region. In this case, NnN_{n} and b/b_{b}/_{b} are the probes for extracting the information about the isospin dependent nucleon nucleon cross section in the medium and the isospin dependent mean field,respectively.Comment: 4 pages,4 figure

    Top-mass effects in differential Higgs production through gluon fusion at order \alpha_s^4

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    Effects from a finite top quark mass on differential distributions in the Higgs+jet production cross section through gluon fusion are studied at next-to-leading order in the strong coupling, i.e. O(αs4)O(\alpha_s^4). Terms formally subleading in 1/mt1/m_t are calculated, and their influence on the transverse momentum and rapidity distribution of the Higgs boson are evaluated. We find that, for the differential K-factor, the heavy-top limit is valid at the 2-3% level as long as the transverse momentum of the Higgs remains below about 150 GeV.Comment: 21 pages, 12 figure

    Определение приоритетности в выборе пациентов из листа ожидания для трансплантации печени

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    Objective: to determine the threshold MELD scores when prioritizing for liver transplantation. Materials and methods. We conducted a cohort study of 350 patients who were waitlisted for liver transplantation between 2015 and 2020. Results. A logistic regression model was used to identify the independent predictors of liver transplantation waitlist mortality. MELD scores and serum albumin at the time of listing were significant predictors of mortality (p = 0.001 and p = 0.004, respectively). Their predictive values were confirmed using ROC (Receiver Operating Characteristic) analysis. The area under the ROC curve (AUC) was 0.883 [95% confidence interval (CI) 0.828–0.939; p < 0.001] for MELD, and 0.841 [95% CI 0.775–0.907; p < 0.001] for serum albumin. Mortality odds ratio was 3.7778, 95% CI (1.619–7.765) provided that the listing MELD score was ≥25. Mortality odds ratio was 2.979 (95% CI 1.63–5.95) provided that the listing serum albumin concentration was ≤30.1 g/L. With a threshold MELD score of 25, there were significant differences between patient survival when comparing patient cohorts with MELD ≥25 and with MELD ≤25 (Log-rank, p < 0.0001). Conclusion. The MELD model has a high predictive ability in prioritization of waitlisted candidates for liver transplantation. The threshold MELD score and mortality predictors were determined. There were significant differences between patient survival among patient cohorts with MELD ≥25 and with MELD ≤25.Цель. Определить пороговое значение показателя MELD при оценке приоритетности выбора пациентов в качестве кандидатов на трансплантацию печени. Материалы и методы. Проведено когортное исследование 350 пациентов, находившихся в листе ожидания трансплантации печени в период с 2015-го по 2020 г. Результаты. Для определения независимых предикторов смертности пациентов в листе ожидания трансплантации печени использовалась логистическая регрессионная модель. Значимыми предикторами смертного исхода стали показатели MELD и альбумина плазмы крови при включении в лист ожидания (р = 0,001 и р = 0,004 соответственно). Предсказательная ценность выявленных предикторов была подтверждена с помощью ROC-анализа (Receiver Operating Characteristic). Площадь под ROC-кривой (Area Under Curve – AUC) для показателя MELD оказалась равной 0,883 [95% доверительный интервал (ДИ) 0,828–0,939; p < 0,001]. AUC ROC для показателя альбумина оказалась равной 0,841 [95% ДИ 0,775–0,907; p < 0,001]. Отношение шансов для развития смертного исхода при условии, если показатель MELD при включении в лист ожидания ≥25, оказалось равным 3,778, 95% ДИ (1,619–7,765). Отношение шансов для развития смертного исхода при условии, если концентрация альбумина плазмы крови при включении в лист ожидания ≤30,1 г/л, оказалось равным 2,979 (95% ДИ 1,63–5,95). При пороговом значении MELD, равном 25 баллам, имелись значимые различия между выживаемостью пациентов при сравнении когорт пациентов с показателями MELD ≥25 и MELD ≤25 (Log-rank, р < 0,0001). Заключение. Исследование подтвердило высокую предсказательную способность модели MELD при определении приоритетности пациентов в листе ожидания для выполнения трансплантации печени. Определено пороговое значение этого показателя, предикторы смертного исхода, показаны значимые различия между выживаемостью пациентов при сравнении когорт пациентов с показателями MELD ≥25 и MELD ≤25

    Fecal calprotectin and microbiota of the gut

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    Analysis of the literature and our research showed that an imbalance of the intestinal microbiota is associated with many diseases. We present some of the mechanisms of disease. Using non-invasive, simple, affordable method of determination of fecal calprotectin reveals the presence and progression of chronic non-specific inflammatory bowel disease, and can be widely used in clinical practic

    Color Reflection Invariance and Monopole Condensation in QCD

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    We review the quantum instability of the Savvidy-Nielsen-Olesen (SNO) vacuum of the one-loop effective action of SU(2) QCD, and point out a critical defect in the calculation of the functional determinant of the gluon loop in the SNO effective action. We prove that the gauge invariance, in particular the color reflection invariance, exclude the unstable tachyonic modes from the gluon loop integral. This guarantees the stability of the magnetic condensation in QCD.Comment: 28 pages, 3 figures, JHEP styl

    Increase the strength characteristics of polymer films by radiation graft polymerization

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    The possibility of increasing the strength characteristics of polymer films based on polyethylene and polyamide by radiation graft polymerization was investigated. Two methods of graft polymerization (direct method and the method of polymer mixtures cross-linking) on the PMMA films surface were studied. The possibility of increasing the strength and elasticity of polymeric films by radiation modification of polymethyl methacrylate was shown

    Higgs production in gluon fusion at next-to-next-to-leading order QCD for finite top mass

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    The inclusive Higgs production cross section from gluon fusion is calculated through NNLO QCD, including its top quark mass dependence. This is achieved through a matching of the 1/mtop expansion of the partonic cross sections to the exact large s-hat limits which are derived from k_T-factorization. The accuracy of this procedure is estimated to be better than 1% for the hadronic cross section. The final result is shown to be within 1% of the commonly used effective theory approach, thus confirming earlier findings.Comment: 28 pages, 14 figure

    The Path Integral Quantization And The Construction Of The S-matrix In The Abelian And Non-Abelian Chern-Simons Theories

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    The cvariant path integral quantization of the theory of the scalar and spinor particles interacting through the abelian and non-Abelian Chern-Simons gauge fields is carried out and is shown to be mathematically ill defined due to the absence of the transverse components of these gauge fields. This is remedied by the introduction of the Maxwell or the Maxwell-type (in the non-Abelian case)term which makes the theory superrenormalizable and guarantees its gauge-invariant regularization and renormalization. The generating functionals are constructed and shown to be formally the same as those of QED (or QCD) in 2+1 dimensions with the substitution of the Chern-Simons propagator for the photon (gluon) propagator. By constructing the propagator in the general case, the existence of two limits; pure Chern-Simons and QED (QCD) after renormalization is demonstrated. By carrying out carefully the path integral quantization of the non-Abelian Chern-Simons theories using the De Witt-Fadeev-Popov and the Batalin-Fradkin- Vilkovisky methods it is demonstrated that there is no need to quantize the dimensionless charge of the theory. The main reason is that the action in the exponent of the path integral is BRST-invariant which acquires a zero winding number and guarantees the BRST renormalizability of the model. The S-matrix operator is constructed, and starting from this S-matrix operator novel topological unitarity identities are derived that demand the vanishing of the gauge-invariant sum of the imaginary parts of the Feynman diagrams with a given number of intermediate on-shell topological photon lines in each order of perturbation theory. These identities are illustrated by an explicit example.Comment: LaTex file, 31 pages, two figure
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