New Mechanism of Magnetoresistance in Bulk Semiconductors: Boundary Condition Effects

We consider the electronic transport in bounded semiconductors in the presence of an external magnetic field. Taking into account appropriate boundary conditions for the current density at the contacts, a change in the magnetoresistance of bulk semiconductors is found as compared with the usual theory of galvanomagnetic effects in boundless media. New mechanism in magnetoresistance connected with the boundary conditions arises. In particular, even when the relaxation time is independent of the electron energy, magnetoresistance is not vanish.Comment: 7 pages, Elsart macro package (LaTeX2e edition

Порівняльна характеристика антропометричних показників, рівня фізичної та технічної підготовленості юних футболістів 12 та 15 років різних ігрових амплуа

Purpose: To develop model characteristics of physical and technical fitness of players of 12 and 15 years of different playing roles.Material and methods. The study was attended by football players of 12 and 15 years of sport school "Areal" Kharkiv, in which the developed technologies were applied in the educational process. In total, 23 forvards, 28 midfielders, 30 defenders and 15 goalkeepers were invited for the survey. Indicators of the running time of segments of 15 m from the course, 30 m from the course and 60 m from the course were determined; shuttle running time 5 to 20 m. Determined the length and weight of the body; Heart rate at rest and heart rate after a shuttle run. From the technical readiness indicators were determined: the time of holding the soccer ball on the foot; juggling, that is, the number of shots of the ball with the foot without losing the ball; time to run a soccer ball on a mission; goal kicks for accuracy; strikes the ball at flight range.Results. Young players of 12 and 15 years of different game specializations differ in terms of physical and technical fitness. The largest number of significant differences were found in the technical readiness of football players for 15 years. Field players at speed capabilities are significantly superior to goalkeepers. Goalkeepers, on the contrary, have lower running speeds. The level of speed endurance is relatively high for defenders and midfielders, as opposed to goalkeepers. The obtained data allowed us to build models of physical development, physical and technical readiness of players of 12 and 15 years of different playing fields, on the basis of which training programs for representatives of different playing roles can be developed.Conclusions. The data obtained indicate the need for a differentiated approach in the training process of young football players, taking into account their playing role. The differentiated approach is more relevant at the age of 15 compared to the age of 12.Цель: разработать модельные характеристики физической и технической подготовленности футболистов 12 и 15 лет разных игровых амплуа.Материал и методы. В исследовании приняли участие футболисты 12 та15 лет ДЮСШ «Ареал» г.. Харькова, в учебно-тренировочном процессе которых применялись разработаны технологии. Всего для обследования были приглашены 23 нападающих, 28 полузащитников, 30 защитников и 15 вратарей. Определялись показатели времени пробегания отрезков 15 м с ходу, 30 м с ходу и 60 м с хода; время челночного бега 5 по 20 м. Определяли длину и массу тела ЧСС покоя и ЧСС после челночного бега. Из показателей технической подготовленности определяли: время содержания футбольного мяча на стопе; жонглирование, то есть количество набивок мяча стопой без потери мяча; время выполнения ведения футбольного мяча по заданию; удары по воротам на точность попадания; удары мяча на дальность полета.Результаты. Юные футболисты 12 и 15 лет разных игровых специализаций различаются между собой по показателям физической и технической подготовленности. Наибольшее количество достоверных различий обнаружено в показателях технической подготовленности футболистов 15 лет.Полевые игроки по скоростным возможностям существенно превосходят вратарей. Вратари, наоборот, имеют более низкие показатели скорости бега. Уровень скоростной выносливости относительно высокий у защитников и полузащитников в отличие от вратарей.Выводы. Полученные данные свидетельствуют о необходимости дифференцированных устных подхода в тренировочном процессе юных футболистов с учетом их игрового амплуа. Дифференцированных устных подход приобретает большую актуальность в 15 лет по сравнению с возрастом 12 лет.Мета: розробити модельні характеристики фізичної та технічної підготовленості футболістів 12 та 15 років різних ігрових амплуа.Матеріал і методи. У дослідженні узяли участь футболісти 12 та15 років ДЮСШ «Ареал» м. Харкова, в навчально-тренувальному процесі яких застосовувалися розроблені технології. Всього для обстеження було запрошено 23 нападаючих, 28 півзахисників, 30 захисників і 15 воротарів. Визначалися показники часу пробігання відрізків15 м з ходу,30 м з ходу та 60 м з ходу; час човникового бігу 5 по20 м. Визначали довжину та масу тіла; ЧСС спокою та ЧСС після човникового бігу. З показників технічної підготовленості визначали: час тримання футбольного м’ча на стопі; жонглювання, тобто кількість набивань м’яча стопою без втрати м’яча; час виконання ведення футбольного м’яча за завданням; удари по воротам на точність влучення; удари м’яча на дальність польоту.Результати. Юні футболісти 12 і 15 років  різних ігрових спеціалізацій розрізняються між собою за показниками фізичної і технічної підготовленості. Найбільша кількість достовірних відмінностей виявлена у показниках технічної підготовленості футболістів 15 років.Польові гравці по швидкісних можливостях істотно перевершують воротарів. Воротарі, навпаки, мають нижчі показники швидкості бігу. Рівень швидкісної витривалості відносно високий у захисників і напівпівзахисників на відміну від воротарів. Отримані дані дозволили побудувати моделі фізичного розвитку, фізичної та технічної підготовленості футболістів 12 та 15 років різних ігрових амплуа, на основі яких можуть бути розроблені програми тренувань для представників різних ігрових амплуа.Висновки. Отримані дані свідчать про необхідність діференційованого підходу в тренувальному процесі юних футболістів з урахуванням їх ігрового амплуа. Діференційований підхід набуває більшу актуальність у 15 років у порівнянні з віком 12 років

Leaders-cheaters in male group cooperation: differences in nonverbal communication and genetic factors

Here we report on the results of an experimental study investigating "who?" emerges as a leader in the context of male group cooperation and "how?" they do that. The study was designed based on the iterated Public Goods Game, played face-to-face in groups composed of four male strangers. The game involved interactions both with and without communication to allow the assessment of individual cooperative strategies, leadership potential, and individual features of positive nonverbal expressiveness during interactions. Along with the individual behavioural characteristics we have addressed personality traits (the Big Five) and an oxytocin receptor gene polymorphism (OXTR: SNP rs53576; A/G) as putative markers of individual sociability. Our results revealed that emergent leaders most often employed the strategy of unconditional cooperation ("altruism") and were characterized by enhanced positive facial expressiveness and extraversion compared to non-leaders. However, a fraction of emergent leaders (25%) turned out to be occasional free-riders ("cheaters"). Their distinctive features were the highest scores on extraversion, exaggerated activity in negotiations, and over-expression of positive nonverbal elements. Given the high efficiency of leaders-cheaters' behaviour, we consider this result as the evidence for supernormal stimuli functioning in humans. Moreover, leaders-cheaters were characterized by a specific allelic frequency of OXTR rs53576 (heterozygosity: AG). The homozygous GG variant of this SNP is argued to be associated with prosociality, and the AA, on the contrary, with poor sociability. The heterozygous variant (AG) probably is a compromise that enables its carriers to successfully combine high social skills with anti-social behavior (free-riding). This finding supports existing evidence on the role of OXTR rs53576 in human social behaviour

On two superintegrable nonlinear oscillators in N dimensions

We consider the classical superintegrable Hamiltonian system given by $H=T+U={p^2}/{2(1+\lambda q^2)}+{{\omega}^2 q^2}/{2(1+\lambda q^2)}$, where U is known to be the "intrinsic" oscillator potential on the Darboux spaces of nonconstant curvature determined by the kinetic energy term T and parametrized by {\lambda}. We show that H is Stackel equivalent to the free Euclidean motion, a fact that directly provides a curved Fradkin tensor of constants of motion for H. Furthermore, we analyze in terms of {\lambda} the three different underlying manifolds whose geodesic motion is provided by T. As a consequence, we find that H comprises three different nonlinear physical models that, by constructing their radial effective potentials, are shown to be two different nonlinear oscillators and an infinite barrier potential. The quantization of these two oscillators and its connection with spherical confinement models is briefly discussed.Comment: 11 pages; based on the contribution to the Manolo Gadella Fest-60 years-in-pucelandia, "Recent advances in time-asymmetric quantum mechanics, quantization and related topics" hold in Valladolid (Spain), 14-16th july 201

A Laser Frequency Comb System for Absolute Calibration of the VTT Echelle Spectrograph

A wavelength calibration system based on a laser frequency comb (LFC) was developed in a co-operation between the Kiepenheuer-Institut f\"ur Sonnenphysik, Freiburg, Germany and the Max-Planck-Institut f\"ur Quantenoptik, Garching, Germany for permanent installation at the German Vacuum Tower Telescope (VTT) on Tenerife, Canary Islands. The system was installed successfully in October 2011. By simultaneously recording the spectra from the Sun and the LFC, for each exposure a calibration curve can be derived from the known frequencies of the comb modes that is suitable for absolute calibration at the meters per second level. We briefly summarize some topics in solar physics that benefit from absolute spectroscopy and point out the advantages of LFC compared to traditional calibration techniques. We also sketch the basic setup of the VTT calibration system and its integration with the existing echelle spectrograph.Comment: 9 pages, 2 figures; Solar Physics 277 (2012

Microscopic mechanisms of spin-dependent electric polarization in 3d oxides

We present a short critical overview of different microscopic models for nonrelativistic and relativistic magnetoelectric coupling including the so-called "spin current scenario", ab-initio calculations, and several recent microscopic approaches to a spin-dependent electric polarization in 3d oxides.Comment: 8 pages, 3 figure

Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios

The decays of massive gravitinos into neutralino dark matter particles and Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may alter the primordial light-element abundances. We present here details of a new suite of codes for evaluating such effects, including a new treatment based on PYTHIA of the evolution of showers induced by hadronic decays of massive, unstable particles such as a gravitino. We also develop an analytical treatment of non-thermal hadron propagation in the early universe, and use this to derive analytical estimates for light-element production and in turn on decaying particle lifetimes and abundances. We then consider specifically the case of an unstable massive gravitino within the constrained minimal supersymmetric extension of the Standard Model (CMSSM). We present upper limits on its possible primordial abundance before decay for different possible gravitino masses, with CMSSM parameters along strips where the lightest neutralino provides all the astrophysical cold dark matter density. We do not find any CMSSM solution to the cosmological Li7 problem for small m_{3/2}. Discounting this, for m_{1/2} ~ 500 GeV and tan beta = 10 the other light-element abundances impose an upper limit m_{3/2} n_{3/2}/n_\gamma < 3 \times 10^{-12} GeV to < 2 \times 10^{-13} GeV for m_{3/2} = 250 GeV to 1 TeV, which is similar in both the coannihilation and focus-point strips and somewhat weaker for tan beta = 50, particularly for larger m_{1/2}. The constraints also weaken in general for larger m_{3/2}, and for m_{3/2} > 3 TeV we find a narrow range of m_{3/2} n_{3/2}/n_\gamma, at values which increase with m_{3/2}, where the Li7 abundance is marginally compatible with the other light-element abundances.Comment: 74 pages, 40 Figure

Measurement of the photon+b+b-jet production differential cross section in ppˉp\bar{p} collisions at \sqrt{s}=1.96~\TeV

We present measurements of the differential cross section dsigma/dpT_gamma for the inclusive production of a photon in association with a b-quark jet for photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is the photon transverse momentum. The b-quark jets are required to have pT>15 GeV and rapidity |y_jet| < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider at sqrt(s)=1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the Sherpa and Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.

Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV

We present final searches of the anomalous gammaWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wgamma, WW, and WZ production with leptonic final states. The analyzed data correspond to up to 8.6/fb of integrated luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96 TeV. We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2 TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154, -0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization, and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL

Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV

We present a search for the production of neutral Higgs bosons decaying into tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tautau pairs, and we then interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL