278 research outputs found

    Nucleon Resonances and Quark Structure

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    A pedagogical review of the past 50 years of study of resonances, leading to our understanding of the quark content of baryons and mesons. The level of this review is intended for undergraduates or first-year graduate students. Topics covered include: the quark structure of the proton as revealed through deep inelastic scattering; structure functions and what they reveal about proton structure; and prospects for further studies with new and upgraded facilities, particularly a proposed electron-ion collider.Comment: 21 pages, 15 figure

    Scanning Probe Techniques for Characterization of Vertically Aligned Carbon Nanotubes

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    This chapter presents the results of experimental studies of the electrical, mechanical and geometric parameters of vertically aligned carbon nanotubes (VA CNTs) using scanning probe microscopy (SPM). This chapter also presents the features and difficulties of characterization of VA CNTs in different scanning modes of the SPM. Advanced techniques for VA CNT characterization (the height, Young’s modulus, resistivity, adhesion and piezoelectric response) taking into account the features of the SPM modes are described. The proposed techniques allow to overcome the difficulties associated with the vertical orientation and high aspect ratio of nanotubes in determining the electrical and mechanical parameters of the VA CNTs by standard methods. The results can be used in the development of diagnostic methods as well as in nanoelectronics and nanosystem devices based on vertically aligned carbon nanotubes (memory elements, adhesive structures, nanoelectromechanical switches, emission structures, etc.)

    Patient adherence after coronary bypass grafting: different facets of same matter. A systematic review

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    Background. Adherence in cardiological patients is a leading challenge due to a high society burden imposed by cardiovascular diseases (CVDs) through morbidity, reduced life expectancy, disability and high mortality rates in population. Despite the availability of highly effective medicines and high-technology care, the success of CVD treatment remains insufficient. A particular focus should be placed on patients with previous coronary artery bypass grafting (CABG).Objectives. A review of reasoning for non-adherence to medication and non-medication management in post-CABG patients and current methods influencing it.Methods. Russian-language and foreign literature was mined in the eLibrary and PubMed databases with the query keywords “medication adherence” [приверженность терапии], “coronary artery disease” [ишемическая болезнь сердца], “coronary artery bypass surgery” [коронарное шунтирование], “coronary revascularisation” [вторичная профилактика после коронарного шунтирования]. The review included papers published within 2016–2020, as well as selected relevant publications from 2003–2015, to cover 52 sources irrespective of study design and language. Content and descriptive analyses were used as research tools.Results. Coronary heart disease (CHD) poses an important health, social and economic problem worldwide as a leading cause of reduced life expectancy, disability and high mortality. Non-compliance with medication significantly bursts medical expenditures [1]. Coronary artery bypass grafting is used widely to treat multivessel coronary lesions both in stable and acute CHD. Secondary preventive techniques successfully preclude adverse post-CABG events, but adherence to post-CABG treatment is often low. The non-adherence rationale rarely links to a single factor but is rather complex and multifaceted. It includes social and economic reasons, systemic health care or personnel, therapy and patient-related factors. Methods are developing and refining to improve adherence to both non-medication and medication interventions.Conclusion. Clinical trials to improve secondary prevention adherence in patients after coronary artery bypass grafting will allow a wider implementation of relevant methods in outpatient management of this patient category

    Exploring the polarization of gluons in the nucleon

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    We give an overview of the current status of investigations of the polarization of gluons in the nucleon. We describe some of the physics of the spin-dependent gluon parton distribution and its phenomenology in high-energy polarized hadronic scattering. We also review the recent experimental results.Comment: 10 pages, 13 figures. Talk presented at the "Second Meeting of the APS Topical Group on Hadronic Physics", Nashville, Tennessee, October 22-24, 2006. Reference adde

    Dijet production as a centrality trigger for p-p collisions at CERN LHC

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    We demonstrate that a trigger on hard dijet production at small rapidities allows to establish a quantitative distinction between central and peripheral collisions in pbar-p and p-p collisions at Tevatron and LHC energies. Such a trigger strongly reduces the effective impact parameters as compared to minimum bias events. This happens because the transverse spatial distribution of hard partons (x >~ 10^{-2}) in the proton is considerably narrower than that of soft partons, whose collisions dominate the total cross section. In the central collisions selected by the trigger, most of the partons with x >~ 10^{-2} interact with a gluon field whose strength rapidly increases with energy. At LHC (and to some extent already at Tevatron) energies the strength of this interaction approaches the unitarity ('black-body') limit. This leads to specific modifications of the final state, such as a higher probability of multijet events at small rapidities, a strong increase of the transverse momenta and depletion of the longitudinal momenta at large rapidities, and the appearance of long-range correlations in rapidity between the forward/backward fragmentation regions. The same pattern is expected for events with production of new heavy particles (Higgs, SUSY). Studies of these phenomena would be feasible with the CMS-TOTEM detector setup, and would have considerable impact on the exploration of the physics of strong gluon fields in QCD, as well as the search for new particles at LHC.Comment: 17 pages, Revtex 4, 14 EPS figures. Expanded discussion of some points, added 3 new figures and new references. Included comment on connection with cosmic ray physics near the GZK cutoff. To appear in Phys Rev

    Deep structure, tectonics and geodynamics of the Sea of Okhotsk region and structures of its folded frame

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    The use of the zonal-block model of the earth's crust for the construction of regional tectonic schemes and sections of the earth's crust based on a complex of geological and geophysical data makes it possible to consider the resulting maps and sections as tectonic models. The main elements of such models are blocks with an ancient continental base and interblock zones formed by complexes of island arcs, an accretionary prism, or oceanic crust. The developed geotectonic model of the Sea of Okhotsk region reflects the features of the deep structure, tectonics, and geodynamics. The Cimmerian Novosibirsk-Chukotka, Verkhoyansk-Kolyma, Kolyma-Omolon, and Amur folded regions and the Alpides of the Koryak-Kamchatka and Sakhalin-Sikhote-Alin folded regions are developed along the northern, western, and southern boundaries of the Sea of Okhotsk megablock with a continental crust type. From the east, the megablock is limited by oceanic basins and island arcs

    SURGICAL CORRECTION OF INSUFFICIENCY OF CEREBRAL BLOOD FLOW AT THE ATHEROSCLEROSIS OF EXTRACEREBRAL ARTERIES

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    There is more than 1 million people who have had a stroke in Russia; the third part of these people are of working age, and only every fourth patient returned to job. This article discusses one of the most effective methods of stroke prevention - the procedure of carotid endarterectomy. We performed 468 reconstructive operations in 448 patients. 65 % (305) of surgeries were open carotid endarterectomies. In other cases, operations of prosthetics or blood flow switching between extracerebral arteries (ECA) (163) were carried out. Short-term results of reconstructive operations showed that 96 % of outcomes were positive. Perioperative mortality at operations made 1.06 %. The general complications made 4.5 %, minor complications were observed in 21 patients (4.4 %). The five years survival rate of patients operated on ECA made 86 %, the main cause of death in recent follow-up period was a cardiac pathology (58 %), brain disorders made 15 %. Among dominating risk factors are coronary heart disease, previous transient ischemic attacks and residual neurologic impairment
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