223 research outputs found

    Homology class of a Lagrangian Klein bottle

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    It is shown that an embedded Lagrangian Klein bottle represents a non-trivial mod 2 homology class in a compact symplectic four-manifold (X,ω)(X,\omega) with c1(X)[ω]>0c_1(X)\cdot[\omega]>0. (In versions 1 and 2, the last assumption was missing. A counterexample to this general claim and the first proof of the corrected result have been found by Vsevolod Shevchishin.) As a corollary one obtains that the Klein bottle does not admit a Lagrangian embedding into the standard symplectic four-space.Comment: Version 3 - completely rewritten to correct a mistake; Version 4 - minor edits, added references; AMSLaTeX, 6 page

    CEM03 and LAQGSM03 - new modeling tools for nuclear applications

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    An improved version of the Cascade-Exciton Model (CEM) of nuclear reactions realized in the code CEM2k and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) have been developed recently at LANL to describe reactions induced by particles and nuclei for a number of applications. Our CEM2k and LAQGSM merged with the GEM2 evaporation/fission code by Furihata have predictive powers comparable to other modern codes and describe many reactions better than other codes; therefore both our codes can be used as reliable event generators in transport codes for applications. During the last year, we have made a significant improvements to the intranuclear cascade parts of CEM2k and LAQGSM, and have extended LAQGSM to describe photonuclear reactions at energies to 10 GeV and higher. We have produced in this way improved versions of our codes, CEM03.01 and LAQGSM03.01. We present a brief description of our codes and show illustrative results obtained with CEM03.01 and LAQGSM03.01 for different reactions compared with predictions by other models, as well as examples of using our codes as modeling tools for nuclear applications.Comment: 12 pages, 10 figures, to be published in Journal of Physics: Conference Series: Proc. Europhysics Conf. on New Trends in Nuclear Physics Applications and Technologies (NPDC19), Pavia, Italy, September 5-9, 200

    Estimated Inpatient Hospital Stay in Individual Wards: Guidelines on Radiation Safety after Radioiodine Therapy

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    Radionuclide therapy safety requirements are regulated by the Russian Radiation Safety Standards (RRSS), which state the maximum allowed radionuclide activity in the body and the equivalent dose rate (EDR) of gamma radiation. Therefore, it is necessary to estimate the time of an inpatient hospital stay in specially designed radionuclide therapy wards. The article presents the findings of individual 131I biokinetics studies in 64 patients admitted to radioiodine therapy of thyrotoxicosis and differentiated thyroid cancer. We developed a method to calculate the time interval to reach the EDR of 20μSv/h and the recommended EDR of 3 and 0.3μSv/h for adults and children, respectively. It is based on the measurement of the 131I excretion constant. Keywords: Radioiodine therapy, Radiation safety, Guidelin

    Composite slab numerical strength test method under partial connection approach

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    The present uneconomic strength determination approach for profiled composite slab (PCS) constitutes a serious challenge that contributed significantly to design conservatism. This study seeks to address this challenge by developing and a subsequent experimental validation of a numerical strength determination function for PCS through implementing a rational-based approach. Hence, a procedural algorithm lead to the development of PCS determination function using longitudinal shear estimation method by considering section slenderness and deck characteristics. The strength test performance between the developed scheme and the experiment-based test results indicates high similarity, demonstrating the viability of the proposed strength determination methodology developed

    Effectiveness of Disinsection and Deratization in Gorno-Altai High-Mountain Natural Plague Focus

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    Epidemic complications in the territory of Gorno-Altai high-mountain natural plague focus, associated with increase in numbers of carriers and vectors of the dangerous diseases, entailed strengthening of preventive element in the system of epidemiological surveillance. Objective of the study was to assess the efficiency of disinsection and deratization during anti-epidemic campaign. Materials and methods. Investigations were performed in 2014-2017 in the territory of Kosh-Agach district of the Republic of Altai, based on the archival and operational records from Altai Plague Control Station, Rospotrebnadzor Administration in the Republic of Altai, and our own data. “Interactive Map on Management of Health Promotion Measures in Gorno-Altai high-mountain natural plague focus” was used as an assessment tool. Results and conclusions. The most hard-hitting sections of preventive complex as regards plague are still disinsection and deratization. Application of advanced methods and means of control over numbers of carriers and vectors of the infection testify to their high anti-epidemic effectiveness. Insecticide and rodenticide treatments of encampments situated in epizootic areas, disinsection and deratization in major population centers in the territory of the focus allowed for the reduction in risk of population infection. Technical efficiency of the field disinsection amounted to 96.7 %, community deratization and disinsection varied from 91.6 to 100 %. Emergency insecticide and rodent treatments in epizootic areas alongside other measures provided for epidemiological welfare on plague

    Nitazoxanide Stimulates Autophagy and Inhibits mTORC1 Signaling and Intracellular Proliferation of Mycobacterium tuberculosis

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    Tuberculosis, caused by Mycobacterium tuberculosis infection, is a major cause of morbidity and mortality in the world today. M. tuberculosis hijacks the phagosome-lysosome trafficking pathway to escape clearance from infected macrophages. There is increasing evidence that manipulation of autophagy, a regulated catabolic trafficking pathway, can enhance killing of M. tuberculosis. Therefore, pharmacological agents that induce autophagy could be important in combating tuberculosis. We report that the antiprotozoal drug nitazoxanide and its active metabolite tizoxanide strongly stimulate autophagy and inhibit signaling by mTORC1, a major negative regulator of autophagy. Analysis of 16 nitazoxanide analogues reveals similar strict structural requirements for activity in autophagosome induction, EGFP-LC3 processing and mTORC1 inhibition. Nitazoxanide can inhibit M. tuberculosis proliferation in vitro. Here we show that it inhibits M. tuberculosis proliferation more potently in infected human THP-1 cells and peripheral monocytes. We identify the human quinone oxidoreductase NQO1 as a nitazoxanide target and propose, based on experiments with cells expressing NQO1 or not, that NQO1 inhibition is partly responsible for mTORC1 inhibition and enhanced autophagy. The dual action of nitazoxanide on both the bacterium and the host cell response to infection may lead to improved tuberculosis treatment

    WNT/β-catenin signaling regulates mitochondrial activity to alter the oncogenic potential of melanoma in a PTEN-dependent manner

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    Aberrant regulation of WNT/β-catenin signaling has a crucial role in the onset and progression of cancers, where the effects are not always predictable depending on tumor context. In melanoma, for example, models of the disease predict differing effects of the WNT/β-catenin pathway on metastatic progression. Understanding the processes that underpin the highly context-dependent nature of WNT/β-catenin signaling in tumors is essential to achieve maximal therapeutic benefit from WNT inhibitory compounds. In this study, we have found that expression of the tumor suppressor, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), alters the invasive potential of melanoma cells in response to WNT/β-catenin signaling, correlating with differing metabolic profiles. This alters the bioenergetic potential and mitochondrial activity of melanoma cells, triggered through regulation of pro-survival autophagy. Thus, WNT/β-catenin signaling is a regulator of catabolic processes in cancer cells, which varies depending on the metabolic requirements of tumors
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