465 research outputs found

    Instrument of Improvement or Degradation: Contemporary University Rankings and Their Problems

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    The paper is devoted to the analyses of current situation in the area of theory and methodology of university rankings. The author identifies three main problems in this area. First of all, it is the problem of relation of measurable and non-measurable dimensions of university activities and the relevant limitation of possibility to use ranking as the universal technology of evaluation. Secondly, it is the relations between objective and subjective data in elaboration of relevant indicators. Thirdly, is the problem of necessity of exclusive and authentic methodology for university ranking or possibility to apply universal methodology. The results of main international and Ukrainian university rankings in 2017 are also presented

    Observation of inverse diproton photodisintegration at intermediate energies

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    The reaction pp->{pp}_s\gamma, where {pp}_s is a proton pair with an excitation energy E_{pp}<3 MeV, has been observed with the ANKE spectrometer at COSY-Juelich for proton beam energies of T_p=0.353, 0.500, and 0.550 GeV. This is equivalent to photodisintegration of a free 1S_0 diproton for photon energies E\gamma ~ T_p/2. The differential cross sections measured for c.m. angles 0 deg.<\theta_{pp}<20 deg. exhibit a steep increase with angle that is compatible with E1 and E2 multipole contributions. The ratio of the measured cross sections to those of np->d\gamma is on the 10^{-3}-10^{-2} level. The increase of the pp->{pp}_s\gamma cross section with T_p might reflect the influence of the Delta(1232) excitation.Comment: 4 pages + 4 figure

    Constrained minimization in the C# # environment

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    Abstract On the basis of the ideas, proposed by one of the authors (I.N. Silin), a suitable software has been developed for constrained data &quot;tting. Constraints may be of arbitrary type; i.e. equalities and inequalities. The simplest possible way has been used. The widely known program FUMILI was re-written in the C# # language. Constraints in the form of inequalities ( )5a were taken into account by changing them into equalities ( )&quot;t and simple inequalities of type t5a. The equalities were taken into account by means of quadratic penalty functions. The suitable software was tested on the model data for the ANKE setup (COSY accelerator, Forschungszentrum JuK lich, Germany)

    Resonance-like coherent production of a pion pair in the reaction pdpdππpd \rightarrow pd\pi\pi in the GeV region

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    The reaction p+dp+d+Xp + d \rightarrow p + d + X was studied at 0.8-2.0 GeV proton beam energies with the ANKE magnetic spectrometer at the COSY synchrotron storage ring. The proton-deuteron pairs emerging with high momenta, 0.6-1.8 GeV/cc, were detected at small angles with respect to the proton beam. Distribution over the reaction missing mass MxM_x reveals a local enhancement near the threshold of the pion pair production specific for the so-called ABC effect. The enhancement has a structure of a narrow bump placed above a smooth continuum. The invariant mass of the dππd\pi\pi system in this enhancement region exhibits a resonance-like peak at Mdππ2.36M_{d\pi\pi} \approx 2.36 GeV/c2c^2 with the width Γ0.10\Gamma \approx 0.10 GeV/c2c^2. A possible interpretation of these features is discussed.Comment: 14 pages, 16 figures, submitted to Eur. Phys. J. A. v2: Added references [42,43] in section IV.A. v3: revised version according to referee remarks v4: revised version according to referee remark

    Mathematical modeling of groundwaters pressure distribution in the underground structures by cylindrical form zone

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    A mathematical model is developed for studying the distribution of groundwater pressure and its variation in the zone of underground structures of a cylindrical shape. Based on the created model, the influence of the thickness of the aquifer, the soil porosity, the filtration coefficient, the viscosity coefficient and the piezoelectric conductivity coefficient on the pressure that groundwater exerts on the lower part of the underground structure is investigated. The analysis of the possibility of pushing the structure and breaking the foundation under the influence of pressure caused by groundwater is analyzed. Analytical formulas are obtained for estimating the stresses in the foundation and predicting the possibility of its destruction

    Determination of unknown parameters of mathematical model using the experimental design theory

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    The range of problems that can be solved with the help of mathematical modeling is constantly increasing, which creates new theoretical problems. One of them is connected with identification of unknown parameters of models. The problem of parameters determination belongs to the class of inverse problems. They are usually considered within the optimization theory. In the present paper, we propose a fundamentally new approach. The method is based on the theory of planning and processing of experiments developed by American scientists Box and Wilson. To evaluate the adequacy of model, a numerical criterion W is formulated depending only on the model parameters a1, a2,... ak. It is shown that the maximum adequacy is achieved for the minimum value of W. Therefore, solving the problem of calculating the parameters is reduced to determination of such values of a1, a2,... ak that provide the minimum value of the criteria W. This problem is solved by the steep ascent method due to Box and Wilson

    Stimulation of spermatogenesis by combined therapy with follicle-stimulating hormone and chorionic gonadotropin for azoospermia and infertility in cases of previous ineffective monotherapy with chorionic gonadotropin and antiestrogen

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    Often there is a need of application of the methods of treatment, directed on increase in quantity of spermatozoa in an ejaculate. In the research efficiency of the combined therapy by preparation follicle-stimulating hormone was estimated and a chorionic gonadotrophin in cases of the previous inefficiency monotherapy a chorionic gonadotrophin and an anti-estrogen. The efficiency of treatment concerning an oligoteratozoospermiya made 65 %. Positive changes of morphology of spermatozoa included improvement of condensation of a chromatin and decrease of the degrading forms. At the same time this treatment was safe and didn»t lead to development of side effects

    First measurements of spin correlations in the np -> d pi^0 reaction

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    The transverse spin correlations Axx and Ayy in the np-> d pi^0 reaction have been measured for the first time in quasi-free kinematics at the COSY-ANKE facility using a polarised deuteron beam incident on a polarised hydrogen cell target. The results obtained for neutron energies close to 353 MeV and 600 MeV are in good agreement with the partial wave analysis of data on the isospin-related pp-> d pi^+ reaction, though the present results cover also the small-angle region, which was largely absent from these data

    Chemical Composition of Fresh Snow from Glaciar Marinelli, Tierra Del Fuego, Chile

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    A fresh-snow sampling campaign was conducted during the late austral summer of 2006 in the accumulation zone of Glaciar Marinelli, located in the Cordillera Darwin, Tierra del Fuego, Chile. Snow samples were analyzed for stable isotopes (delta(18)O, major soluble ions (Na\u27, K\u27, Ca, Mg, a NO(3)(-), SO(4)(2-), MS(-)) and major and trace elements (Na, Mg, Al, Fe, Ca, Sr, Cd, Cs, Ba, La, Ce, Pr, Dy, Ho, Er, Bi, U, As, Ti, V, Cr, Mn). The dominance of marine chemistry resembles that in studies from Patagonian glaciers. Snow chemistry was dominantly loaded by marine species (Cl(-), Na(+) and ssSO(4)(2-)), while contributions of crustal species (e.g. Al and Fe) were very low. Empirical orthogonal function analysis suggests two possible dust sources, one represented by Al and Fe and the other by La, Ce and Pr. Enrichment-factor calculations suggest the majority of elements are within average upper-crustal ratios, but major enrichments of Bi and Cd (hundreds of times) suggest possible anthropogenic sources. Linear correlation of delta(18)O and barometric pressure (r = 0.60, p \u3c 0.007) suggests a potential \u27amount effect\u27 relationship between depleted delta(18)O ratios and stronger storm conditions (e.g. greater precipitation). The snow-chemistry records from Glaciar Marinelli are the first measured in Tierra del Fuego, the southernmost glaciated region outside Antarctica
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