The formation of Uranus and Neptune among Jupiter and Saturn

The outer giant planets, Uranus and Neptune, pose a challenge to theories of planet formation. They exist in a region of the Solar System where long dynamical timescales and a low primordial density of material would have conspired to make the formation of such large bodies ($\sim$ 15 and 17 times as massive as the Earth, respectively) very difficult. Previously, we proposed a model which addresses this problem: Instead of forming in the trans-Saturnian region, Uranus and Neptune underwent most of their growth among proto-Jupiter and -Saturn, were scattered outward when Jupiter acquired its massive gas envelope, and subsequently evolved toward their present orbits. We present the results of additional numerical simulations, which further demonstrate that the model readily produces analogues to our Solar System for a wide range of initial conditions. We also find that this mechanism may partly account for the high orbital inclinations observed in the Kuiper belt.Comment: Submitted to AJ; 38 pages, 16 figure

Structure of the uncomplexed DNA repair enzyme endonuclease VIII indicates significant interdomain flexibility

Escherichia coli endonuclease VIII (Nei) excises oxidized pyrimidines from DNA. It shares significant sequence homology and similar mechanism with Fpg, a bacterial 8-oxoguanine glycosylase. The structure of a covalent Nei–DNA complex has been recently determined, revealing critical amino acid residues which are important for DNA binding and catalysis. Several Fpg structures have also been reported; however, analysis of structural dynamics of Fpg/Nei family proteins has been hindered by the lack of structures of uncomplexed and DNA-bound enzymes from the same source. We report a 2.8 Å resolution structure of free wild-type Nei and two structures of its inactive mutants, Nei-E2A (2.3 Å) and Nei-R252A (2.05 Å). All three structures are virtually identical, demonstrating that the mutations did not affect the overall conformation of the protein in its free state. The structures show a significant conformational change compared with the Nei structure in its complex with DNA, reflecting a ∼50° rotation of the two main domains of the enzyme. Such interdomain flexibility has not been reported previously for any DNA glycosylase and may present the first evidence for a global DNA-induced conformational change in this class of enzymes. Several local but functionally relevant structural changes are also evident in other parts of the enzyme

Polyelectrolyte microcapsules as a tool to enhance photosensitizing effect of chlorin E6

The inclusion of chlorin E6 in polymer capsules reduced dark toxicity and increased the photosensitizing effect compared to the free form of ClE

Оптимизация проведения спинномозговой анестезии для оперативного родоразрешения у женщин с высокой массой тела

Objective: to develop a scheme for calculating the dose of a local anesthetic (LA) for spinal anesthesia (SA) during operative delivery, by taking into account the individual physical characteristics of a female patient. Subjects and methods. The course of SA was analyzed in 35 overweight women. In accordance with the body mass index (BMI), the patients were divided into 3 groups. In each group the authors identified subgroups with no arterial hypotension development (NAHD) and with arterial hypotension development (AHD) until a fetus was extracted. In each specific case, the used dose of a LA was compared with its dose calculated by the height of a patient and the difference between the BMI of a female patient and that taken as the normal value of 25 kg/m2. Results. When the doses of a LA, which were used for SA, were investigated, in all cases the doses of a LA were determined to be smaller than those calculated by the height of a patient. In the NAHD subgroups, the percentage reduction in LA doses was significantly greater than that in the AHD subgroups in all the three groups and the dose was increased as BMI rose from 13.6±1.6% in the NAHD subgroup in Group 1 to 34.7±1.2% in the same subgroup in Group 3. By comparing the percentage reduction in the LA dose and excess BMI, the authors established the correction coefficient for the LA dose calculated by height and derived a formula for calculating the dose of a LA, by taking into account the physical characteristics of a female patient. Conclusion. The LA dose calculation formula considering the individual physical characteristics of a female patient makes the determination of a LA dose more precise in order to optimize the course of anesthesia from the hemodynamic profile. Key words: spinal anesthesia, obesity, cesarean section.Цель исследования . Разработать схему расчета дозы МА для проведения СМА при оперативном родоразрешении с учетом индивидуальных физических характеристик пациентки. Материал и методы. В исследовании анализировали течение СМА у 35 женщин с повышенной массой тела. Женщины с учетом индекса массы тела (ИМТ) были разделены на 3 группы. В каждой из групп были выделены подгруппы с отсутствием развития артериальной гипотонии (ПН) и подгруппы с развитием артериальной гипотонии (НГ) до извлечения плода. В каждом отдельном случае проведения СМА проводили сравнение применяемой дозы местного анестетика (МА) с дозой МА, рассчитанной по росту и разницей между ИМТ пациентки и ИМТ, принятого за норму, равного 25 кг/м2. Результаты. При исследовании доз МА, применяемых для проведения СМА, определено, что во всех случаях дозы МА были ниже доз, рассчитанных по росту пациентки. В подгруппах с отсутствием развития АГ процентное снижение дозы МА было достоверно выше, чем в подгруппах с развитием АГ во всех 3-х группах и увеличивалось по мере нарастания ИМТ с 13,6±1,6% в ПН 1-й группе, до 34,7±1,2% в ПН 3-й. Путем сравнения процентного снижения дозы МА и избытка ИМТ установлен коэффициент коррекции дозы МА, рассчитанной по росту и выведена формула расчета дозы МА с учетом физических характеристик пациентки. Заключение. Формула расчета дозы МА, учитывающая индивидуальные физические характеристики пациентки, способствует более точному определению дозы МА для оптимизации течения анестезии по гемодинамическому профилю. Ключевые слова: спинномозговая анестезия, ожирение, кесарево сечение

Vortex phases in mesoscopic cylinders with suppressed surface superconductivity

Vortex structures in mesoscopic cylinder placed in external magnetic field are studied under the general de Gennes boundary condition for the order parameter corresponding to the suppression of surface superconductivity. The Ginzburg-Landau equations are solved based on trial functions for the order parameter for vortex-free, single-vortex, multivortex, and giant vortex phases. The equilibrium vortex diagrams in the plane of external field and cylinder radius and magnetization curves are calculated at different values of de Gennes "extrapolation length" characterizing the boundary condition for the order parameter. The comparison of the obtained variational results with some available exact solutions shows good accuracy of our approach.Comment: RevTex, 11 pages, 10 figure

Topological mirror symmetry with fluxes

Motivated by SU(3) structure compactifications, we show explicitly how to construct half--flat topological mirrors to Calabi--Yau manifolds with NS fluxes. Units of flux are exchanged with torsion factors in the cohomology of the mirror; this is the topological complement of previous differential--geometric mirror rules. The construction modifies explicit SYZ fibrations for compact Calabi--Yaus. The results are of independent interest for SU(3) compactifications. For example one can exhibit explicitly which massive forms should be used for Kaluza--Klein reduction, proving previous conjectures. Formality shows that these forms carry no topological information; this is also confirmed by infrared limits and old classification theorems.Comment: 35 pages, 5 figure

Late Permian magnetostratigraphy on the eastern Russian platform

The Late Permian is characterized palaeomagnetically by the transition from the long-lasting Permo-Carboniferous reversed polarity superchron (PCRS; also called: Kiaman reversed superchron) to the subsequent Permo-Triassic mixed polarity superchron, often called Illawarra mixed polarity superchron. Many discussions have been devoted to the exact time of the onset of the Illawarra reversals. Apparently contradictory data have been obtained from magnetostratigraphic sediment successions formed in different environments in many regions of the world. These sediments have been dated using classical geological or palaeontological correlation methods without the possibility of absolute age control because volcanogenic materials are missing. Application of the local or regional stratigraphic schemes leads to difficulties and apparent diachronous age estimates of the end of the PCRS. This paper shows that in agreement with earlier investigations, the continental red beds of the Upper Permian Tatarian stage on the eastern Russian platform record the Kiaman/Illawarra boundary. The Illawarra reversal sequence measured in a type section at the Volga river can be correlated well with the corresponding polarity pattern found in the Tethyan realm if one assumes a longer duration of the Tatarian than previously suggested

Relativistic theory of inverse beta-decay of polarized neutron in strong magnetic field

The relativistic theory of the inverse beta-decay of polarized neutron, $\nu _{e} + n \to p + e ^{-}$, in strong magnetic field is developed. For the proton wave function we use the exact solution of the Dirac equation in the magnetic filed that enables us to account exactly for effects of the proton momentum quantization in the magnetic field and also for the proton recoil motion. The effect of nucleons anomalous magnetic moments in strong magnetic fields is also discussed. We examine the cross section for different energies and directions of propagation of the initial neutrino accounting for neutrons polarization. It is shown that in the super-strong magnetic field the totally polarized neutron matter is transparent for neutrinos propagating antiparallel to the direction of polarization. The developed relativistic approach can be used for calculations of cross sections of the other URCA processes in strong magnetic fields.Comment: 41 pages in LaTex including 11 figures in PostScript, discussion on nucleons AMM interaction with magnetic field is adde

Cohomology Groups of Deformations of Line Bundles on Complex Tori

The cohomology groups of line bundles over complex tori (or abelian varieties) are classically studied invariants of these spaces. In this article, we compute the cohomology groups of line bundles over various holomorphic, non-commutative deformations of complex tori. Our analysis interpolates between two extreme cases. The first case is a calculation of the space of (cohomological) theta functions for line bundles over constant, commutative deformations. The second case is a calculation of the cohomologies of non-commutative deformations of degree-zero line bundles.Comment: 24 pages, exposition improved, typos fixe

The origin of paramagnetic magnetization in field-cooled YBa2Cu3O7 films

Temperature dependences of the magnetic moment have been measured in YBa_2Cu_3O_{7-\delta} thin films over a wide magnetic field range (5 <= H <= 10^4 Oe). In these films a paramagnetic signal known as the paramagnetic Meissner effect has been observed. The experimental data in the films, which have strong pinning and high critical current densities (J_c ~ 2 \times 10^6 A/cm^2 at 77 K), are quantitatively shown to be highly consistent with the theoretical model proposed by Koshelev and Larkin [Phys. Rev. B 52, 13559 (1995)]. This finding indicates that the origin of the paramagnetic effect is ultimately associated with nucleation and inhomogeneous spatial redistribution of magnetic vortices in a sample which is cooled down in a magnetic field. It is also shown that the distribution of vortices is extremely sensitive to the interplay of film properties and the real experimental conditions of the measurements.Comment: RevTex, 8 figure