Newtonian and Pseudo-Newtonian Hill Problem

A pseudo-Newtonian Hill problem based on the Paczynski-Wiita pseudo-Newtonian potential that reproduces general relativistic effects is presented and compared with the usual Newtonian Hill problem. Poincare maps, Lyapunov exponents and fractal escape techniques are employed to study bounded and unbounded orbits. In particular we consider the systems composed by Sun, Earth and Moon and composed by the Milky Way, the M2 cluster and a star. We find that some pseudo-Newtonian systems - including the M2 system - are more stable than their Newtonian equivalent.Comment: 12 pages, 4 figures, 1 tabl

Ассоциация полиморфизма гена IL12Bс предрасположенностью к псориазу в популяцииСеверо-Западного региона России

The IL12B gene encodes protein р40 being a common subunit of interleukin-12 and interleukin-23 playing an important part in the pathogenesis of psoriasis. The IL12B gene has polymorphism rs12188300, which can be associated with the risk of psoriasis development. The goal of the study was to assess the distribution of alleles of polymorphism rs12188300 in psoriatic patients in the Northwestern region of Russia. Genotyping was carried out using the real-time allele-specific polymerase chain reaction. An increased occurrence of a rare allele T in psoriatic patients as compared to healthy people was observed (OR = 1.96, р = 0.0007). The occurrence of the rare allele T in patients with psoriatic arthritis was higher than in the control group (OR = 3.49, р = 0.005). These results suggest that rs12188300 polymorphism of the IL12B gene is a new genetic marker of psoriasis and psoriatic arthritis.Ген IL12B кодирует белок р40, являющийся общей субъединицей интерлейкина-12 и интерлейкина-23, играющих важную роль в патогенезе псориаза. Ген IL12B содержит полиморфизм rs12188300, который может быть ассоциирован с риском развития псориаза. Целью работы явилось изучение распределения аллелей полиморфизма rs12188300 у больных псориазом Северо-Западного региона России. Генотипирование проводилось методом аллельспецифической полимеразной цепной реакции в режиме реального времени. Выявлено повышение встречаемости редкого аллеля Т среди больных псориазом по сравнению со здоровыми лицами (OR = 1,96, р = 0,0007). Частота редкого аллеля Т среди больных псориатическим артритом была выше, чем в группе контроля (OR = 3,49, р = 0,005). Полученные результаты позволяют предположить, что полиморфизм rs12188300 гена IL12B является новым генетическим маркером псориаза и псориатического артрита

A molecular dynamics study on the equilibrium magnetization properties and structure of ferrofluids

We investigate in detail the initial susceptibility, magnetization curves, and microstructure of ferrofluids in various concentration and particle dipole moment ranges by means of molecular dynamics simulations. We use the Ewald summation for the long-range dipolar interactions, take explicitly into account the translational and rotational degrees of freedom, coupled to a Langevin thermostat. When the dipolar interaction energy is comparable with the thermal energy, the simulation results on the magnetization properties agree with the theoretical predictions very well. For stronger dipolar couplings, however, we find systematic deviations from the theoretical curves. We analyze in detail the observed microstructure of the fluids under different conditions. The formation of clusters is found to enhance the magnetization at weak fields and thus leads to a larger initial susceptibility. The influence of the particle aggregation is isolated by studying ferro-solids, which consist of magnetic dipoles frozen in at random locations but which are free to rotate. Due to the artificial suppression of clusters in ferro-solids the observed susceptibility is considerably lowered when compared to ferrofluids.Comment: 33 pages including 12 figures, requires RevTex

Semileptonic B decays into even parity charmed mesons

By using a constituent quark model we compute the form factors relevant to semileptonic transitions of B mesons into low-lying p-wave charmed mesons. We evaluate the q^2 dependence of these form factors and compare them with other model calculations. The Isgur-Wise functions tau(1/2) and tau(3/2) are also obtained in the heavy quark limit of our results.Comment: 11 pages, 2 figure

Measurement of plasma density formed at passing of a sequeence of relativistic electron bunches through the neutral gas

Using an open barrel-shaped resonator (OBR) plasma density, produced by a sequence of duration 2 μs of relativistic electron bunches, each of energy 4.5 MeV and charge 0.16 nC, in air at pressure of 10…60 Torr was measured. The plasma density was determined from the shift of the OBR resonant frequency estimated after measuring the reduction of oscillations amplitude in plasma loaded OBR at the initial frequency of OBR. It was shown that the maximum density of the produced plasma reaches 3·10¹⁰ cm⁻³ at wakefield excitation in a semi-infinite plasma waveguide and 10¹¹ – in plasma resonatorС помощью открытого бочкообразного резонатора (ОБР) измерена плотность плазмы, образуемая последовательностью релятивистских электронных сгустков длительностью 2 мкс, с энергией 4.5 MэВ, зарядом 0.16 нК каждого в воздухе с давлением 10...60 Торр. Плотность плазмы определялась по сдвигу резонансной частоты ОБР, оцененного по измерению уменьшения амплитуды колебаний в нагруженном плазмой ОБР на исходной резонансной частоте ОБР. Показано, что максимальная плотность образуемой плазмы достигает 3·10¹⁰cм⁻³ для возбуждения кильватерного поля в полуоткрытом волноводе и 10¹¹ см⁻³ – в плазменном резонаторе.За допомогою відкритого бочкоподібного резонатора (ВБР) виміряна густина плазми, яка утворюється послідовністю релятивістських електронних згустків тривалістю 2 мкс, з енергією 4.5 МеВ, зарядом 0.16 нК кожного в повітрі з тиском 10...60 Торр. Густина плазми визначалася по зсуву резонансної частоти ВБР, яка оцінювалася по вимірюванню зменшення амплітуди коливань у навантаженому плазмою ВБР на вихідній резонансній частоті ВБР. Показано, що максимальна густина утворюваної плазми досягає 3·10¹⁰ cм⁻³ при збудженні кільватерного поля в напіввідкритому хвилеводі і 10¹¹ см⁻³ – у плазмовому резонаторі

One-pion transitions between heavy baryons in the constituent quark model

Single pion transitions of S wave to S wave, P wave to S wave and P wave to P wave heavy baryons are analyzed in the framework of the Heavy Quark Symmetry limit (HQS). We use a constituent quark model picture for the light diquark system with an underlying SU(2N_{f}) X O(3) symmetry to reduce the number of the HQS coupling factors required to describe these transitions. We also use the quantum theory of angular momentum to rewrite the one-pion transitions constituent quark model results in a more general form using the 6j- and 9j-symbols. We finally estimate the decay rates of some single pion transitions between charm baryon states.Comment: Latex, 33 pages including 2 figures (Postscript). Some typos are corrected with minor changes. Two references were added to the final version which will appear in Phy. Rev.

Experimental investigation of the current plasma lens in the non-uniform magnetic field

The ion focusing by the uniform (along the radius and length) current lens was investigated elsewhere. In this work the more complicated, strongly non-uniform (in z-direction) case is considered when parameters of the focusing channel (the current channel radius, current density, focusing azimuthal magnetic field) are changed sufficiently on the focusing distance by the external magnetic field. Theoretically the problem is being solved in details in Ref. [4]. In this work the numerical calculations and experimental investigations are presented