71 research outputs found

    requirements for naive CD4+ T cell stimulation

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    Human primary dendritic cells (DCs) are heterogeneous by phenotype, function, and tissue localization and distinct from inflammatory monocyte-derived DCs. Current information regarding the susceptibility and functional role of primary human DC subsets to Mycobacterium tuberculosis (Mtb) infection is limited. Here, we dissect the response of different primary DC subsets to Mtb infection. Myeloid CD11c+ cells and pDCs (C-type lectin 4C+ cells) were located in human lymph nodes (LNs) of tuberculosis (TB) patients by histochemistry. Rare CD141hi DCs (C-type lectin 9A+ cells) were also identified. Infection with live Mtb revealed a higher responsiveness of myeloid CD1c+ DCs compared to CD141hi DCs and pDCs. CD1c+ DCs produced interleukin (IL)-6, tumor necrosis factor α, and IL-1β but not IL-12p70, a cytokine important for Th1 activation and host defenses against Mtb. Yet, CD1c+ DCs were able to activate autologous naïve CD4+ T cells. By combining cell purification with fluorescence-activated cell sorting and gene expression profiling on rare cell populations, we detected in responding CD4+ T cells, genes related to effector-cytolytic functions and transcription factors associated with Th1, Th17, and Treg polarization, suggesting multifunctional properties in our experimental conditions. Finally, immunohistologic analyses revealed contact between CD11c+ cells and pDCs in LNs of TB patients and in vitro data suggest that cooperation between Mtb-infected CD1c+ DCs and pDCs favors stimulation of CD4+ T cells

    Colour reconnection in e+e- -> W+W- at sqrt(s) = 189 - 209 GeV

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    The effects of the final state interaction phenomenon known as colour reconnection are investigated at centre-of-mass energies in the range sqrt(s) ~ 189-209 GeV using the OPAL detector at LEP. Colour reconnection is expected to affect observables based on charged particles in hadronic decays of W+W-. Measurements of inclusive charged particle multiplicities, and of their angular distribution with respect to the four jet axes of the events, are used to test models of colour reconnection. The data are found to exclude extreme scenarios of the Sjostrand-Khoze Type I (SK-I) model and are compatible with other models, both with and without colour reconnection effects. In the context of the SK-I model, the best agreement with data is obtained for a reconnection probability of 37%. Assuming no colour reconnection, the charged particle multiplicity in hadronically decaying W bosons is measured to be (nqqch) = 19.38+-0.05(stat.)+-0.08 (syst.).Comment: 30 pages, 9 figures, Submitted to Euro. Phys. J.

    Search for R-Parity Violating Decays of Scalar Fermions at LEP

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    A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data collected with the OPAL detector at LEP. The data samples analysed correspond to an integrated luminosity of about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle is expected to be unstable. Searches of R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield final states consisting of leptons, jets, or both with or without missing energy. No significant single-like excess of events has been observed with respect to the Standard Model expectations. Limits on the production cross- section of scalar fermions in R-parity violating scenarios are obtained. Constraints on the supersymmetric particle masses are also presented in an R-parity violating framework analogous to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.

    Measurement of the Hadronic Photon Structure Function F_2^gamma at LEP2

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    The hadronic structure function of the photon F_2^gamma is measured as a function of Bjorken x and of the factorisation scale Q^2 using data taken by the OPAL detector at LEP. Previous OPAL measurements of the x dependence of F_2^gamma are extended to an average Q^2 of 767 GeV^2. The Q^2 evolution of F_2^gamma is studied for average Q^2 between 11.9 and 1051 GeV^2. As predicted by QCD, the data show positive scaling violations in F_2^gamma. Several parameterisations of F_2^gamma are in agreement with the measurements whereas the quark-parton model prediction fails to describe the data.Comment: 4 pages, 2 figures, to appear in the proceedings of Photon 2001, Ascona, Switzerlan

    Search for the Standard Model Higgs Boson with the OPAL Detector at LEP

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    This paper summarises the search for the Standard Model Higgs boson in e+e- collisions at centre-of-mass energies up to 209 GeV performed by the OPAL Collaboration at LEP. The consistency of the data with the background hypothesis and various Higgs boson mass hypotheses is examined. No indication of a signal is found in the data and a lower bound of 112.7GeV/C^2 is obtained on the mass of the Standard Model Higgs boson at the 95% CL.Comment: 51 pages, 21 figure

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Стартап выведения на внутриигровой рынок IT-продукта на базе платформы Steam

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    Анализ способов ведения коммерческой деятельности в рамках платформы Steam и игры Counter-Strike: Global Offensive. Разработка it-продукта для повышения эффективности работы на платформе Steam. Оформление разработки в качестве стартапа.Analysis of ways of doing business within the Steam platform and the game Counter-Strike: Global Offensive. Development of an it-product to improve the efficiency of work on the Steam platform. Registration of development as a startup

    Оценка воздействия социальных медиа на политические и социокультурные взгляды молодежи в условиях глобальной трансформации общества (на примере видеоблогинга)

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    Исследование социальных медиа - одна из самых динамично развивающихся областей современной социологии. Актуальность исследования обусловлена трансформацией общественных ценностей, формированием глобальной политической и культурной среды и значительным влиянием современных информационных технологий на всю социокультурную систему. Целью исследования является оценка воздействия социальных медиа на социокультурную трансформацию общества и анализ влияния видеоблогинга как формы социальных медиа на молодых людей в возрасте от 17 до 30 лет. Методы. В процессе исследования был использован абстрактно-логический подход на основе системного анализа существующих эмпирических данных и онлайн-опроса, проведенного в социальной сети «ВКонтакте» среди студентов МГУ им. М.В. Ломоносова и студентов Национального исследовательского университета «Высшая школа экономики». Опрос содержал большое количество вариантов ответов (перечисление имен известных блогеров) и возможность добавления респондентом собственных вариантов ответов и комментариев. Результаты. Выяснилось, что воздействие блогеров на мировоззрение зрителей молодого поколения значительно. Половина опрошенных респондентов в возрасте от 17 до 30 лет интересуются политическими блогами, что говорит о возрастающей роли видеоблогинга среди молодежи в сети Интернет. Этот вид социальных медиа становится ареной политической борьбы за влияние на мировоззрение молодежи. Большинство участников опроса уделяют внимание политизированным блогерам, в частности Алексею Навальному. Значительная часть респондентов также следит за научно-популярными блогами, что может говорить о желании получать новые знания в сжатом и упрощенном виде.The study of social media is one of the most dynamically developing areas of modern sociology. The relevance of the study is caused by transformation of social values, emergence of global political and cultural environment, and significant impact of modern information technologies on the entire socio-cultural system. The aim of the study is to assess the impact of social media on the socio-cultural transformation of society and to analyze the impact of video blogging as a form of social media on young people aged 17 to 30 years. The method. The abstract-logical approach based on the system analysis of existing empirical data and an online-survey was used. The survey was conducted in the social network Vkontakte among students of the Lomonosov Moscow State University and National Research University «Higher School of Economics». The survey had a large number of answers and the possibility for respondents to add their own answers and comments. Results. It was found that the impact of bloggers on the worldview of the younger generation is significant. Half of the respondents aged 17 to 30 are interested in political blogs, which indicates the increasing role of video blogging among young people on the internet. This type of social media becomes battleground for political struggle for influence on the worldview of young people. The majority of respondents pay attention to politicized bloggers, in particular Alexei Navalny. A significant part of respondents also follows popular science blogs, which may indicate a desire to gain new knowledge in a concise and simplified form

    Measurements of top-quark pair differential cross-sections in the eμe\mu channel in pppp collisions at s=13\sqrt{s} = 13 TeV using the ATLAS detector

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