743 research outputs found

    Technology evaluation professional competencies of students of secondary vocational education

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    The article touches upon the issue of experience in the development and implementation of technology of the assessment of professional competencies of students of secondary vocational educational establishments based on the rating system. The author suggests the principle of formation of the final decision at the examination (qualification) according to the professional module: whether the student mastered or not the professional module and the solution for process automationВ статье рассматривается опыт разработки и внедрения технологии оценивания профессиональных компетенций студента СПО на основе рейтинговой системы. Предлагается принцип формирования итогового решения на экзамене (квалификационном) по профессиональному модулю: освоил или не освоил студент профессиональный модуль, а также решение для автоматизации процесс

    Feynman Diagrams and Differential Equations

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    We review in a pedagogical way the method of differential equations for the evaluation of D-dimensionally regulated Feynman integrals. After dealing with the general features of the technique, we discuss its application in the context of one- and two-loop corrections to the photon propagator in QED, by computing the Vacuum Polarization tensor exactly in D. Finally, we treat two cases of less trivial differential equations, respectively associated to a two-loop three-point, and a four-loop two-point integral. These two examples are the playgrounds for showing more technical aspects about: Laurent expansion of the differential equations in D (around D=4); the choice of the boundary conditions; and the link among differential and difference equations for Feynman integrals.Comment: invited review article from Int. J. Mod. Phys.

    CASTOR: Centauro and Strange Object Research in nucleus-nucleus collisions at LHC

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    We describe the CASTOR detector designed to probe the very forward, baryon-rich rapidity region in nucleus-nucleus collisions at the LHC. We present a phenomenological model describing the formation of a QGP fireball in a high baryochemical potential environment, and its subsequent decay into baryons and strangelets. The model explains Centauros and the long-penetrating component and makes predictions for the LHC. Simulations of Centauro-type events were done. To study the response of the apparatus to new effects different exotic species (DCC, Centauros, strangelets etc.) were passed through the deep calorimeter. The energy deposition pattern in the calorimeter appears to be a new clear signature of the QGP.Comment: Talk given by E. Gladysz-Dziadus for the CASTOR group, Intern. Workshop on Nuclear Theory, 10-15 June, 2002, Bulgaria, Rila Mountains, 15 pages, 14 figure

    Absorption of phi mesons in near-threshold proton-nucleus reactions

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    In the framework of the nuclear spectral function approach for incoherent primary proton--nucleon and secondary pion--nucleon production processes we study the inclusive ϕ\phi meson production in the interaction of 2.83 GeV protons with nuclei. In particular, the A-dependences of the absolute and relative ϕ\phi meson yields are investigated within the different scenarios for its in-medium width as well as for the cross section ratio σpnpnϕ/σppppϕ\sigma_{pn \to pn{\phi}}/{\sigma_{pp \to pp{\phi}}}. Our model calculations take into account the acceptance window of the ANKE facility used in a recent experiment performed at COSY. They show that the pion--nucleon production channel contributes distinctly to the ϕ\phi creation in heavy nuclei in the chosen kinematics and, hence, has to be taken into consideration on close examination of the dependences of the phi meson yields on the target mass number with the aim to get information on its width in the medium. They also demonstrate that the experimentally unknown ratio σpnpnϕ/σppppϕ\sigma_{pn \to pn{\phi}}/{\sigma_{pp \to pp{\phi}}} has a weak effect on the A-dependence of the relative ϕ\phi meson production cross section at incident energy of present interest, whereas it is found to be appreciably sensitive to the phi in-medium width, which means that this relative observable can indeed be useful to help determine the above width from the direct comparison the results of our calculations with the future data from the respective ANKE-at-COSY experiment.Comment: 16 pages, 9 figure

    Ultraviolet crosslinking of corneal collagen in patients with thin cornea. Literature review

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    For the treatment of progressive keratoconus in the early stages, corneal collagen crosslinking is currently actively used. This technique is based on the stabilization of the pathological process by increasing the biomechanical properties of the own cornea. The thickness of the cornea less than 400 microns significantly limits the possibility of a standard cross-linking procedure performing.The article analyzes the literature data on the use of various methods of corneal crosslinking with a corneal thickness of less than 400 microns, which signifi cantly limits the possibilities of the standard procedure.It is known, that during crosslinking, at the initial stage, de-epithelialization of the cornea is performed, which, in the postoperative period, leads to a pronounced corneal syndrome. This determined the direction of the fi rst modifi cations of the technique associated with the use of partial de-epithelialization or its complete absence. Later, during cross-linking of “thin” corneas, techniques with the use of additional covering materials were actively used in order to replenish the missing corneal tissue of the patient during the UV irradiation procedure. Among them are the use of a soft contact lens without an ultraviolet fi lter, the use of a corneal lenticule obtained after SMILE surgery, the use of a protective fl ap of the donor cornea obtained using a femtosecond laser from the residual stroma of the corneal disc after descemet membrane transplantation or posterior lamellar keratoplasty. The variety of the proposed modifications and the ongoing search for better options indicate the demand for this technology and the need for further research, taking into account the individual characteristics of the patient’s ectasia

    Near-threshold production of omega mesons in the pn -> d omega reaction

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    The first measurement of the p n -> d omega total cross section has been achieved at mean excess energies of Q = 28 and 57 MeV by using a deuterium cluster-jet target. The momentum of the fast deuteron was measured in the ANKE spectrometer at COSY-Juelich and that of the slow "spectator" proton p(sp) from the p d -> p(sp) d omega reaction in a silicon telescope placed close to the target. The cross sections lie above those measured for p p -> p p omega but seem to be below theoretical predictions.Comment: 7 pages, 8 figures; second approach to describe the background has been added; results changed insignificantly, EPJ in pres

    e^+e^- Pair Production from γ\gamma A Reactions

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    We present a calculation of e^+e^- production in γA\gamma A reactions at MAMI and TJNAF energies within a semi-classical BUU transport model. Dilepton invariant mass spectra for γ\gammaC, γ\gammaCa and γ\gammaPb are calculated at 0.8, 1.5 and 2.2 GeV. We focus on observable effects of medium modifications of the ρ\rho and ω\omega mesons. The in-medium widths of these mesons are taken into account in a dynamical, consistent way. We discuss the transport theoretical treatment of broad resonances.Comment: 42 pages including 16 figure
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