1,445 research outputs found
The white dwarf in dwarf nova SDSS J080434.20+510349.2: Entering the instability strip?
SDSS J080434.20+510349.2 is the WZ type binary that displayed rare outburst
in 2006 (Pavlenko et al., 2007). During the long-lasting tail of the late stage
of the outburst binary shown the two-humped or four-humped profile of the
orbital light modulation. The amplitude of orbital light curve decreased while
the mean brightness decreased, more over that occurred 10 times faster
during the fast outburst decline in respect to the late quiet state of slow
outburst fading. There were no white dwarf pulsations detected neither 1 - 1.5
months prior to the outburst nor in 1.5 - 2 months after the 2006 outburst in
this system. However the strong non-radial pulsations with period 12.6 minutes
and mean amplitude of 0.05^m were first detected in V band with 2.6-m Shajn
mirror telescope of the Crimean astrophysical observatory in ~ 8 months after
the outburst. The evolution of pulsations over two years in 2006 - 2008 is
considered. It is supposed that pulsations first appeared when the cooling
white dwarf (after the outburst) entered the instability strip although the
possibility of temporary lack of pulsations at some occasions also could not be
excluded.Comment: Submitted to Proceedings of 16th European White Dwarf Workshop
(EUROWD08
Superconductivity Controlled by Polarization in Field-Effect Devices of Confined Geometry
We propose a concept for superconducting electric field-effect devices based
on superconducting films sandwiched between ferroelectric layers. We provide
theoretical calculations that indicate how the field effect in these devices
could be amplified, which can be experimentally probed even at the current
stage of film fabrication techniques.Comment: to appear in Applied Physics Letters, 3 pages RevTeX4, 3 figure
Jet-induced gauge field instabilities in the quark-gluon plasma: A kinetic theory approach
We discuss the properties of the collective modes of a system composed by a
thermalized quark-gluon plasma traversed by a relativistic jet of partons. The
transport equations obeyed by the components of the plasma and of the jet are
studied in the Vlasov approximation. Assuming that the partons in the jet can
be described with a tsunami-like distribution function we derive the
expressions of the dispersion law of the collective modes. Then the behavior of
the unstable gauge modes of the system is analyzed for various values of the
velocity of the jet, of the momentum of the collective modes and of the angle
between these two quantities. We find that the most unstable modes are those
with momentum orthogonal to the velocity of the jet and that these
instabilities appear when the velocity of the jet is higher than a threshold
value, which depends on the plasma and jet frequencies. The results obtained
within the Vlasov approximation are compared with the corresponding results
obtained using a chromohydrodynamical approach.The effect we discuss here
suggests a possible collective mechanism for the description of the jet
quenching phenomena in heavy ion collisions.Comment: 13 pages, 6 figure
Modulation of Superconducting Properties by Ferroelectric Polarization in Confined FE-S-FE Films
We show that the electric polarization at the interface with ultrathin
superconducting (S) films sandwiched between ferroelectric (FE) layers allows
achievement of substantially stronger modulation of inner carrier density and
superconducting transition temperature as compared to FE-S bilayers typically
used in superconducting FETs. We find that not only the larger penetration
depths but also the pairing symmetry should be responsible for the fact that
the electric field effect in high temperature superconductors is much stronger
than in conventional systems. Discussing the advantages of multilayers, we
propose a novel design concept for superconducting electric field-effect
transistors based on ferroelectric films.Comment: 5 pages RevTex4, 6 figure
A catalogue of bright (K <9) M dwarfs
Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL's low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method to that of previous work to produce 8479 K <9 M dwarfs. Low-resolution spectroscopy was obtained of a sample of the objects found using this selection method to gain statistics on their spectral type and physical properties. Results show a spectral-type range of K7-M4V. This catalogue is the most complete collection of K <9 M dwarfs currently available and is made available here.Peer reviewe
Temporal logic model of performance in high school = Темпорально-логическая модель деятельности обучаемого в вузе
Pavlenko V. N., Tkachenko Y. M. Temporal logic model of performance in high school = Темпорально-логическая модель деятельности обучаемого в вузе. Journal of Education, Health and Sport. 2015;5(7):258-270. ISSN 2391-8306. DOI 10.5281/zenodo.19970http://ojs.ukw.edu.pl/index.php/johs/article/view/2015%3B5%287%29%3A258-270https://pbn.nauka.gov.pl/works/584328http://dx.doi.org/10.5281/zenodo.19970Formerly Journal of Health Sciences. ISSN 1429-9623 / 2300-665X. Archives 2011 – 2014 http://journal.rsw.edu.pl/index.php/JHS/issue/archive Deklaracja.Specyfika i zawartość merytoryczna czasopisma nie ulega zmianie.Zgodnie z informacją MNiSW z dnia 2 czerwca 2014 r., że w roku 2014 nie będzie przeprowadzana ocena czasopism naukowych; czasopismo o zmienionym tytule otrzymuje tyle samo punktów co na wykazie czasopism naukowych z dnia 31 grudnia 2014 r.The journal has had 5 points in Ministry of Science and Higher Education of Poland parametric evaluation. Part B item 1089. (31.12.2014).© The Author (s) 2015;This article is published with open access at Licensee Open Journal Systems of Kazimierz Wielki University in Bydgoszcz, Poland and Radom University in Radom, PolandOpen Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited.This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercialuse, distribution and reproduction in any medium, provided the work is properly cited.The authors declare that there is no conflict of interests regarding the publication of this paper.Received: 15.06.2015. Revised 05.07.2015. Accepted: 12.07.2015. TEMPORAL LOGIC MODEL OF PERFORMANCE IN HIGH SCHOOLТЕМПОРАЛЬНО-ЛОГИЧЕСКАЯ МОДЕЛЬ ДЕЯТЕЛЬНОСТИ ОБУЧАЕМОГО В ВУЗЕ V. N. Pavlenko, Y. M. TkachenkoВ. Н. Павленко, Ю. М. Ткаченко National Aerospace University «Kharkiv Aviation Institute», UkraineНациональный аэрокосмический университет им. Н. Е. Жуковского «ХАИ», Украина V.N. Pavlenko,NationalAerospaceUniversity«Kharkiv Aviation Institute», Ukraine Chkalova str. 17,Kharkiv,Ukraine, 61070E-mail: [email protected] Y.M. Tkachenko,NationalAerospaceUniversity«Kharkiv Aviation Institute», Ukraine Chkalova str. 17,Kharkiv,Ukraine, 61070E-mail: [email protected] Abstract: The one of the stages of the approach to the organization of computer decision support to determine the trajectory of training of students in universities, namely the synthesis of model student. For the synthesis of the student model used mathematical apparatus of temporal logic. The form of a software implementation, the student model is representation in the form of an intelligent agent. Further stages of developing a new approach based on the development of the model of the student group as a community of intelligent agents, and on the notion of the learning process of students in the form of multi-agent system. A multi-agent system will be used to support decision-making by different levels (deans, vice-rector for scientific and pedagogical work) in the event of disputes in the learning process of individual students and student groups. Keywords: student, student group, the trajectory of education, educational process, process model, multi-agent systems, intelligent agents, temporal logic. Аннотация: изложен один из этапов реализации подхода к организации компьютерной поддержки принятия решений по определению траектории обучения студентов в ВУЗах, а именно синтез модели обучаемого. Для синтеза модели обучаемого использован математический аппарат темпоральной логики. Формой программной реализации модели обучаемого является его представление в виде интеллектуального агента. Дальнейшие этапы разрабатываемого подхода основаны на разработке модели студенческой группы как сообщества интеллектуальных агентов, и на представлении процесса обучения студентов в форме мультиагентной системы. Мультиагентная система будет использоваться для поддержки принятия решений руководителями разных уровней (деканами, проректорами по научно-педагогической работе) при возникновении спорных ситуаций в процессе обучения как отдельных студентов, так и студенческих групп. Ключевые слова: студент, студенческая группа, траектория обучения, образовательный процесс, процессная модель, мультиагентные системы, интеллектуальные агенты, темпоральная логика
Masses, Oxygen and Carbon abundances in CHEPS dwarf stars
Reproduced with permission from Astronomy & Astrophysics. © 2019 ESOContext. We report the results from the determination of stellar masses, carbon, and oxygen abundances in the atmospheres of 107 stars from the Calan-Hertfordshire Extrasolar Planet Search (CHEPS) programme. Our stars are drawn from a population with a significantly super-solar metallicity. At least 10 of these stars are known to host orbiting planets. Aims. In this work, we set out to understand the behaviour of carbon and oxygen abundance in stars with different spectral classes, metallicities, and V sin i within the metal-rich stellar population. Methods. Masses of these stars were determined using data from Gaia DR2. Oxygen and carbon abundances were determined by fitting the absorption lines. We determined oxygen abundances with fits to the 6300.304 Å O I line, and we used 3 lines of the C I atom and 12 lines of the C 2 molecule for the determination of carbon abundances. Results. We determine masses and abundances of 107 CHEPS stars. There is no evidence that the [C/O] ratio depends on V sin i or the mass of the star within our constrained range of masses, i.e. 0.82 5 km s -1) are massive stars.Peer reviewedFinal Published versio
- …