3,131 research outputs found
Impact of nanosecond proton beam processing on nanoblocks of copper
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
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
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 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 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 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, and 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
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. . Terms
formally subleading in 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
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
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
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
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
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
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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