96 research outputs found

    Pulsar Magnetospheric Emission Mapping: Images and Implications of Polar-Cap Weather

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    The beautiful sequences of ``drifting'' subpulses observed in some radio pulsars have been regarded as among the most salient and potentially instructive characteristics of their emission, not least because they have appeared to represent a system of subbeams in motion within the emission zone of the star. Numerous studies of these ``drift'' sequences have been published, and a model of their generation and motion articulated long ago by Ruderman & Sutherland (1975); but efforts thus far have failed to establish an illuminating connection between the drift phemomenon and the actual sites of radio emission. Through a detailed analysis of a nearly coherent sequence of ``drifting'' pulses from pulsar B0943+10, we have in fact identified a system of subbeams circulating around the magnetic axis of the star. A mapping technique, involving a ``cartographic'' transform and its inverse, permits us to study the character of the polar-cap emission ``map'' and then to confirm that it, in turn, represents the observed pulse sequence. On this basis, we have been able to trace the physical origin of the ``drifting-subpulse'' emission to a stably rotating and remarkably organized configuration of emission columns, in turn traceable possibly to the magnetic polar-cap ``gap'' region envisioned by some theories.Comment: latex with five eps figure

    Observations of Non-radial Pulsations in Radio Pulsars

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    We introduce a model for pulsars in which non-radial oscillations of high spherical degree (l) aligned to the magnetic axis of a spinning neutron star reproduce the morphological features of pulsar beams. In our model, rotation of the pulsar carries a pattern of pulsation nodes underneath our sightline, reproducing the longitude stationary structure seen in average pulse profiles, while the associated time-like oscillations reproduce "drifting subpulses"--features that change their longitude between successive pulsar spins. We will show that the presence of nodal lines can account for observed 180 degree phase jumps in drifting subpulses and their otherwise poor phase stability, even if the time-like oscillations are strictly periodic. Our model can also account for the "mode changes" and "nulls" observed in some pulsars as quasiperiodic changes between pulsation modes of different l or radial overtone n, analogous to pulsation mode changes observed in oscillating white dwarf stars. We will discuss other definitive and testable requirements of our model and show that they are qualitatively supported by existing data. While reserving judgment until the completion of quantitative tests, we are inspired enough by the existing observational support for our model to speculate about the excitation mechanism of the non-radial pulsations, the physics we can learn from them, and their relationship to the period evolution of pulsars.Comment: 28 pages, 9 figures (as separate png files), Astrophysical Journal, in pres

    An Empirical Model for the Radio Emission from Pulsars

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    A model for slow radio pulsars is proposed which involves the entire magnetosphere in the production of the observed radio emission. It is argued that observations of pulsar profiles suggest that a feedback mechanism exists between the star surface and the null charge surface, requiring particle flow in both directions. In their flow to and from the surface the particles execute an azimuthal drift around the magnetic pole, thereby creating a ring of discrete `emission nodes' close to the surface. Motion of the nodes is observed as the well-known subpulse `drift', but is interpreted here as a small residual component of the real particle drift. The nodes can therefore move in either direction, or even remain stationary. A precise fit is found for the pulsar PSR0943+10. Azimuthal interactions between different regions of the magnetosphere depend on the angle between the magnetic and rotation axes and influence the conal type, as observed. The requirement of intermittent weak pair-production in an outergap suggests a natural evolutionary link between radio and gamma-ray pulsars.Comment: 17 pages 8 figure

    Organizational and pedagogical conditions for training teachers under distance education framework

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    © Author(s).Distance education in a professional higher school is of particular importance in terms of fundamental changes in modern educational institutions. This form of training together with the expansion of information technologies can effectively solve the problem of training students and life-long learning. Distance education is able to solve the problem of teacher training more effectively than any other method of education. In the same context, the opportunities of distance education to develop verbal and cogitative activities and information culture are considered. As a result of the use of network principles, the integrity of educational institutions can be effectively guaranteed and realized in continuity of principles and approaches to the management of different functional and territorial subsystems, and in the more distant future - its equitable integration into the world community

    Toward An Empirical Theory of Pulsar Emission VIII: Subbeam Circulation and the Polarization-Modal Structure of Conal Beams

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    The average polarization properties of conal single and double profiles directly reflect the polarization-modal structure of the emission beams which produce them. These average properties require that the circulating subbeam systems which produce conal beams entail paired PPM and SPM emission elements which are offset from each other in both magnetic azimuth and magnetic colatitude. A clear delineation of the modal polarization topology of the conal beam promises to address fundamental questions about the nature and origin of this modal emission--and the modal parity at the outer beam edges is a fact of considerable significance. The different angular dependences of the modal ``beamlets'' suggests that the polarization modes are generated via propagation effects. This argument may prove much stronger if the modal emission is fundamentally only partially polarized. Several theories now promise quantitative comparison with the observations.Comment: Submitted to Astrophysical Journa

    Performance of a plastic scintillator developed using styrene monomer polymerization

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    This paper presents a newly developed plastic scintillator produced in collaboration with Turkiye Energy, Nuclear and Mineral Research Agency (TENMAK). The scintillator is manufactured using thermal polymerization of commercially available styrene monomer. The absorption spectrum of the scintillator exhibited two absorption bands at 225 nm and 340 nm, with an absorption edge observed at 410 nm. The wavelength of the emitted light was measured in the range of 400-800 nm, with a maximum intensity at 427 nm. Monoenergetic electrons from the 137Cs source were used to evaluate the characteristics of the new scintillator, particularly its light yield. As the light readout the MAPD-3NM type silicon photomultiplier array (4 x 4) with an active area of 15 x 15 mm2, assembled using single MAPDs with an active area of 3.7 x 3.7 mm2, was used. The light yield of the scintillator was determined to be 6134 photons/MeV. In addition, the efficiency of the scintillator for gamma rays with an energy of 662 keV was found to be approximately 1.8 %. A CmBe neutron source was employed to evaluate its fast neutron detection performance. However, neutron/gamma discrimination using pulse shape discrimination (charge integration) method was not observed. The results demonstrate the potential of a newly produced plastic scintillator for various applications, particularly in radiation monitoring and detection systems.Comment: 7 pages, 7 figure

    The effect of platinum compounds on the viability of cultured malignant neoplasm cells

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    The aim of the study – to study the effect of cycloplatinated complexes on the viability of tumor cells and the detection of chemical compounds for the creation of new antitumor drugs.Цель исследования – изучить влияние циклоплатинированных комплексов на жизнеспособность опухолевых клеток и синтезировать химические соединения для создания новых противоопухолевых препаратов

    Апробация методики «Bayley Scales of Infant and Toddler Development – Third Edition»

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    Introduction. There is currently no universal comprehensive measurement tool for the assessment of children development in the Russian Federation (RF). The Bayley-III scales developed by American researchers are widely used as such a tool. Numerous research groups recognize the need to modify the original scales before using them in a new linguistic and socio-cultural environment. Methods. The authors (a) translated the original Bayley-III manual into Russian, (b) tested the tool by assessing cognitive, language, and motor development of 163 Russian children aged 2–11 months, and (c) made an indirect comparison of the mean scale scores of neuropsychological development and those obtained from the original American sample of children using Student’s t-test. Results. The modified version of the Bayley-III manual has been successfully tested in the RF. The indices of language and motor development of the children examined in this study did not statistically differ from the original American data (10 points). Higher scores were obtained for the cognitive scale (10.7 versus 10; p = 0.003). However, this effect was not very pronounced (Cohen’s d = 0.25). Discussion. The indices of neuropsychological development of Russian children fully comply with the original Bayley-III norms, which opens up new possibilities for its use in the RF. Slightly higher scores of the cognitive scale among Russian children do not generally affect the compliance with the original tool, since the difference was not significant. The results of this study can be extrapo-lated to full-term Caucasian children aged 2–11 months, whose parents have at least secondary education and average level of earnings. The widespread use of Bayley-III requires its further adaptation in larger and more representative samples of children from different regions of the RF with the additional assessment of social-emotional development as well as adaptive behavior. © 2020, Russsian Psychological Society. All rights reserved

    Massive blood loss during highly traumatic surgical intervention in pediatric oncology (clinical case)

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    Introduction. Massive perioperative blood loss that accompanies major surgical interventions is a specific critical condition, the  pathogenesis of which is dominated by severe hypovolemia, anemia, and threatening coagulopathy in combination with powerful shockogenic sympathoadrenal stress. Both massive blood loss itself and massive transfusion are associated with a significant risk of serious complications, including death. It is worth noting that information on the survival of patients after replacement of several circulating blood volume (CBV) is limited, and most of the articles are devoted to adult patients with highly traumatic surgical interventions.The objective was to present the experience in managing the patient with blood loss of more than 5.5 CBV according to the MT protocol adopted at the Research Institute of Pediatric Oncology and Hematology. The 3-year-old patient underwent surgical intervention in the following volume: median laparotomy, nephradrenalectomy on the right (lesion 10–15–20 cm in size), paracaval and aortocaval lymph node dissection (conglomerate 7–8 cm in size), resection of S5-S6-S7 liver segments, resection of the right domes of the diaphragm. During the surgical  intervention of 440 minutes (7.3 hours), the total blood loss was 5.5 CBV (5.500 ml).Results. After surgery, he was transferred to prolonged assisted ventilation of the lungs, the duration of which was 2 days. On the 3rd day after the operation, adjuvant polychemotherapy was started. 17 days after the operation, the patient was transferred to the specialized department for further treatment. The patient was alive for a year after surgery.Conclusion. Maintenance of homeostasis, normothermia, normocoagulation through basic infusion therapy with balanced crystalloid solutions, targeted transfusion therapy with the introduction of fresh frozen plasma, transfusion of donor platelets and donor  erythrocytes/autoerythrocytes during anesthesia in the child with extremely massive blood loss, contributed to early post-anesthetic rehabilitation,  provided the opportunity to continue special treatment in the intensive care unit

    The structure of the oropharyngeal genus Candida fungi community in HIVinfected patients

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    At the present time virtually no data are available about the structure of the genus Candida fungus able to target HIV-infected patients and serve as an etiological factor of candidiasis. The aforementioned shaped the aim of the study: to examine structure of the Candida genus community colonizing the oropharynx in HIV-infected patients with clinical manifestations of oropharyngeal candidiasis. There was conducted a microbiological study of the oropharynx in 31 HIV-infected patients (51.6% males and 48.4% females) with clinical manifestations of oropharyngeal candidiasis treated at Moscow Infectious Clinic No. 2 inpatient department in the years 2015–2017. We confirmed the diversity of the oropharyngeal Candida spp. community found in HIV-infected patients. Total 52 isolates of the genus Candida were isolated. C. albicans dominated in 57.7% cases, whereas C. glabrata prevailed (21.1%) among non-albicans species. Minor components were represented by C. tropicalis (11.5%) and C. krusei (9.6%). C. albicans and C. glabrata were sensitive to polyenes, whereas minor community components — to itroconazole and clotrimazole. The vast majority of fungal strains were resistant to fluconazole. The genus Candida community reveals a unique architecture so that any member may exist in the oropharyngeal biotope of HIV-infected patients as a monoculture or in association: homogeneous, consisting of a single species strains, or heterogeneous, formed by several species. Candida fungi in 18 patients (58.1%) were isolated as a monoculture, whereas in 13 (41.9%) subjects — in association consisting of 34 isolates (65.4% of total number), of which 16 (30.8%) and 18 (34.6%) were isolated from homogeneous and heterogeneous associations, respectively. There were identified 9 two-component associations (69.2%), and 4 (30.8%) consisting of three or more components. It turned out that pattern of the examined community was mainly determined by species composition that agrees with previous data. Most common associations were presented by C. krusei (100%) and C. albicans (73.3%). Upon that, most often C. albicans (72.7%) formed a homogeneous type of associations. Sensitivity of Candida fungi to antimycotic drugs also depended on the architecture of related community. C. albicans isolates in heterogeneous associations revealed a wide range of resistance acquired by contact with non-albicans species
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