768 research outputs found
Ladder and zig-zag Feynman diagrams, operator formalism and conformal triangles
We develop an operator approach to the evaluation of multiple integrals for
multiloop Feynman massless diagrams. A commutative family of graph building
operators for ladder diagrams is constructed and investigated. The
complete set of eigenfunctions and the corresponding eigenvalues for the
operators are found. This enables us to explicitly express a wide
class of four-point ladder diagrams and a general two-loop propagator-type
master diagram (with arbitrary indices on the lines) as Mellin-Barnes-type
integrals. Special cases of these integrals are explicitly evaluated. A certain
class of zig-zag four-point and two-point planar Feynman diagrams (relevant to
the bi-scalar -dimensional "fishnet" field theory and to the calculation of
the -function in -theory) is considered. The graph building
operators and convenient integral representations for these Feynman diagrams
are obtained. The explicit form of the eigenfunctions for the graph building
operators of the zig-zag diagrams is fixed by conformal symmetry and these
eigenfunctions coincide with the 3-point correlation functions in
-dimensional conformal field theories. By means of this approach, we exactly
evaluate the diagrams of the zig-zag series in special cases. In particular, we
find a fairly simple derivation of the values for the zig-zag multi-loop
two-point diagrams for . The role of conformal symmetry in this approach,
especially a connection of the considered graph building operators with
conformal invariant solutions of the Yang-Baxter equation is investigated in
detail
Transnational Organized Crime and its Perspectives in Conditions of Global Instability
The article examines transnational organized crime, the ways of it’s classification, its types and subjects. The characteristic of directions, where crime groups have their activities. Also there is a complex of reasons of development of international crime, the solving of which could increase the level of the global security
Contemporary Methods of Treating Children with Autoimmune Nephric Diseases
The review is dedicated to the analysis of contemporary therapies and efficacy thereof for treating children autoimmune nephric diseases. The authors describe peculiarities of using the conventional therapy in children and discuss alternative treatments using cyclosporine, tacrolimus, budesonide and ursodeoxycholic acid, as well as the need in using the second-line drugs for treating patients with resistant autoimmune nephric diseases. The review touches upon the promising approaches to the treatment of this category of patients
Experimental method and statistical analysis to fit tumor growth model using SPECT/CT imaging: A preclinical study
Background: Over the last decade, several theoretical tumor-models have been developed to describe tumor growth. Oncology imaging is performed using various modalities including computed tomography (CT), magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT) and fluorodeoxyglucose-positron emission tomography (FDG-PET). Our goal is to extract useful, otherwise hidden, quantitative biophysical parameters (such as growth-rate, tumor-necrotic-factor, etc.) from these serial images of tumors by fitting mathematical models to images. These biophysical features are intrinsic to the tumor types and specific to the study-subject, and expected to add valuable information on the tumor containment or spread and help treatment plans. Thus, fitting realistic but practical models and assessing parameter-errors and degree of fit is important. Methods: We implemented an existing theoretical ode-compartment model and variants and applied them for the first time, in vivo. We developed an inversion algorithm to fit the models for tumor growth for simulated as well as in vivo experimental data. Serial SPECT/CT scans of mice breast-tumors were acquired, and SPECT data was used to segment the proliferating-layers of tumors. Results: Results of noisy data simulation and inversion show that 5 out of 7 parameters were recovered to within 4.3% error. In particular, tumor growth-rate parameter was recovered to 0.07% error. For model fitting to in vivo mice-tumors, regression analysis on the P-layer volume showed R2 of 0.99 for logistic and Gompertzian while surface area model yielded R2=0.96. For the necrotic layer the R2 values were 0.95, 0.93 and 0.94 respectively for surface-area, logistic and Gompertzian. The Akaike Information Criterion (AIC) weights of the models (giving their relative probability of being the best Kullback-Leibler (K-L) model among the set of candidate models) were 0, 0.43 and 0.57 for surface-area, logistic and Gompertzian models. Conclusions: Model-fitting to mice tumor studies demonstrates feasibility of applying the models to in vivo imaging data to extract features. Akaike information criterion (AIC) evaluations show Gompertzian or logistic growth model fits in vivo breast-tumors better than surface-area based growth model
The main features of the service sector and ways of its improvement on the example of the city Magnitogorsk
В данной статье рассмотрены основные проблемы и трудности, связанные на сегодняшний день со сферой услуг и торговли.This article describes the main problems and difficulties to date with the scope of services and trade
Современные методы лечения детей с аутоиммунными заболеваниями печени
The review is dedicated to the analysis of contemporary therapies and efficacy thereof for treating children autoimmune nephric diseases. The authors describe peculiarities of using the conventional therapy in children and discuss alternative treatments using cyclosporine, tacrolimus, budesonide and ursodeoxycholic acid, as well as the need in using the second-line drugs for treating patients with resistant autoimmune nephric diseases. The review touches upon the promising approaches to the treatment of this category of patients. В обзоре проанализированы современные схемы терапии и их эффективность у детей с аутоиммунными заболеваниями печени. Описаны особенности применения стандартного режима терапии у детей, рассмотрены альтернативные схемы лечения с использованием циклоспорина, такролимуса, будесонида и урсодезоксихолевой кислоты, а также необходимость применения препаратов второй линии для лечения больных с резистентными случаями аутоиммунных заболеваний печени. Освещены перспективные направления лечения этой категории больных.
Long term time variability of cosmic rays and possible relevance to the development of life on Earth
An analysis is made of the manner in which the cosmic ray intensity at Earth
has varied over its existence and its possible relevance to both the origin and
the evolution of life. Much of the analysis relates to the 'high energy' cosmic
rays () and their variability due to the changing
proximity of the solar system to supernova remnants which are generally
believed to be responsible for most cosmic rays up to PeV energies. It is
pointed out that, on a statistical basis, there will have been considerable
variations in the likely 100 My between the Earth's biosphere reaching
reasonable stability and the onset of very elementary life. Interestingly,
there is the increasingly strong possibility that PeV cosmic rays are
responsible for the initiation of terrestrial lightning strokes and the
possibility arises of considerable increases in the frequency of lightnings and
thereby the formation of some of the complex molecules which are the 'building
blocks of life'. Attention is also given to the well known generation of the
oxides of nitrogen by lightning strokes which are poisonous to animal life but
helpful to plant growth; here, too, the violent swings of cosmic ray
intensities may have had relevance to evolutionary changes. A particular
variant of the cosmic ray acceleration model, put forward by us, predicts an
increase in lightning rate in the past and this has been sought in Korean
historical records. Finally, the time dependence of the overall cosmic ray
intensity, which manifests itself mainly at sub-10 GeV energies, has been
examined. The relevance of cosmic rays to the 'global electrical circuit'
points to the importance of this concept.Comment: 18 pages, 5 figures, accepted by 'Surveys in Geophysics
SNP genes of immune response mediators and predisposition to development of socially significant diseases
Allele typing of single-nucleotide polymorphisms (SNPs) may be used in predictive medicine and to determine targets for the most effective treatment strategies for various diseases. The purpose of the present work was to investigate the association between the SNPs of inflammatory genes, e.g., IL10 (C819T; rs1800871; C592A; rs1800872); IL4 (C589T; rs2243250); fibrosis-related factors - TGFβ1 (G915C; rs1800471); MMP1 (1607insG; rs1799750); apoptosis-regulators (TNFRSF11B G1181C; rs2073618); vasoconstricting factors (CRP C3872T; rs1205); CYP1A1 (A2454G; rs1048943), endothelial dysfunction (EDN1 G925T; rs5370); (NOS3 C786T; rs2070744) and development of coronary heart disorders, breast cancer, bronchial asthma (BA) and threatened miscarriage in early pregnancy among population of the Republic of Adygea.DNA samples of unrelated donors and patients (n = 74) with verified diagnoses of bronchial asthma (n = 13), coronary heart disease (n = 10), breast cancer (n = 10) and threatened miscarriage in the first trimester of pregnancy (n = 8) were isolated from peripheral blood leukocytes and typed by allele-specific polymerase chain reaction with electrophoretic detection of results using commercial tests-systems of NPF “Litech”, Moscow.The study in a group of Adygea residents has revealed the statistical significance for the “normal” Arg25-allelic variant of the TGFβ1 gene (p < 0.05; F = 0.038; OR = 3.231; 95% CI = 1.081-9.656) in the development of bronchial asthma. There were no significant differences in SNP rs1800471 of the TGFβ1 gene in the groups with cardiovascular, oncological diseases and gestational disorders (p > 0.05). The frequency distribution of allelic variants NOS3 C786T; TNFRSF11B G1181C; 1607insG of the MMP1 gene; G925T of the EDN1 gene, and CYP1A1 2454G in the examined patients with cardiovascular disease and breast cancer did not significantly differ from the control group (p > 0.05). The statistical significance for the frequency of allelic variants rs1799750 (MMP1 gene) in cases of threatened early miscarriage and in women with a physiological course of pregnancy (F = 0.096; p < 0.05%: OR = 6.0) was close to reliable, but with a confidence interval > 1.0 (95% CI = 0,98036,716), thus requiring further research.The obtained data could be sufficient in order to suggest predisposition for bronchial asthma, as well as to develop a set of preventive measures taking into account the individual characteristics of each patient
Gene polymorphisms of IL-1β (C511T), IL-17A (G197A), IL-12B (A1188C), TNFα (G308A) and IL-4 (C589T) associated with threat of early reproductive losses
Prevalence of threatened miscarriage is 16-25% of all pregnancies. The symptomatics of the threatened miscarriage in the first trimester may develop due to conversion of initial inflammatory reaction that disturbs the intersystemic and local interactions in the endometrium, followed by placental insufficiency, intrauterine fetal affection and spontaneous abortion. The aim of our work was to study the association between single nucleotide polymorphisms (SNPs) of some cytokine genes, e.g., IL-1β (C511T, rs16944), IL-17A (G197A, rs2275913), IL-12B (A1188C, rs3212227), TNFα (G308A, rs1800629), and IL-4 (C589T, rs2243250) and the risk of early reproductive losses among residents of Adyghe Republic (RA). The work was carried out at the Immunogenetic Laboratory of our Research Institute of Complex Problems. The allelic variants of cytokine genes were detected by SNP-method in 106 samples of genomic DNA in women with the threatened abortion in 1st trimester (n = 58) and the uncomplicated gestation (n = 48). SNP-typing of polymorphic variants of cytokine genes IL-1β, IL-17A, IL-12B, TNFα and IL-4 was carried out by PCR (polymerase chain reaction) with allele-specific primers and electrophoretic detection of results on test systems of (Litech, Moscow). Statistical analysis of experimental data was carried out by SPSS Statistical program 17.0. The correspondence of SNP distributions to expected values at Hardy—Weinberg equilibrium and comparison of allelic variants/ genotypes frequencies were performed using the χ2 criterion (Chi-square with Yates correction), odd ratios (OR) detected at significance level p < 0.05 and 95% confidence interval (95% CI). Reliability of the differences for the SNP frequencies for small samples was evaluated using the Fisher’s exact criterion. Heterozygous variant (C511T; OR = 3.46; 95% Cl: 1.04-11.54) and homozygous “mutant” genotypes (T511T; OR = 5.71; 95% Cl: 1.12-29.09) of the main proinflammatory IL-1β was significantly associated (p < 0.05) with the risk of developing threatening miscarriage in the Adygea residents. The -511Т allele of IL-1β gene, and -1188C variant of IL-12B gene increase the risk of the early termination of pregnancy, respectively, 5.8-fold (95% Cl: 2.4213.92; p = 0.00004), and 2.97-fold (95% Cl: 1.23-7.19; p = 0.01). The “mutant” -511T allelic variant of the IL-1 p gene is associated with the risk of developing a symptome complex of threatening miscarriage in Russian ethnic group (p = 0.0001; OR = 14.09), and in Adygea ethnic group (p = 0.02; OR = 8.17), which is almost undetectable in women with normal pregnancy in the first trimester. Thus, only С511Т (rs16944) in IL-1β gene and A1188C (rs3212227) in IL-12B gene of the five typed cytokine genes may be used as marker polymorphisms of gestational distress for the women in Adygea
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