Longitudinal magnetic excitation in KCuCl3 studied by Raman scattering under hydrostatic pressures

We measure Raman scattering in an interacting spin-dimer system KCuCl3 under hydrostatic pressures up to 5 GPa mediated by He gas. In the pressure-induced quantum phase, we observe a one-magnon Raman peak, which originates from the longitudinal magnetic excitationand is observable through the second-order exchange interaction Raman process. We report the pressure dependence of the frequency, halfwidth and Raman intensity of this mode.Comment: 4 pages, 3 figures, inpress in JPCS as a proceeding of LT2

Raman and fluorescence contributions to resonant inelastic soft x-ray scattering on LaAlO3_3/SrTiO3_3 heterostructures

We present a detailed study of the Ti 3$d$ carriers at the interface of LaAlO$_3$/SrTiO$_3$ heterostructures by high-resolution resonant inelastic soft x-ray scattering (RIXS), with special focus on the roles of overlayer thickness and oxygen vacancies. Our measurements show the existence of interfacial Ti 3$d$ electrons already below the critical thickness for conductivity and an increase of the total interface charge up to a LaAlO$_3$ overlayer thickness of 6 unit cells before it levels out. By comparing stoichiometric and oxygen deficient samples we observe strong Ti 3$d$ charge carrier doping by oxygen vacancies. The RIXS data combined with photoelectron spectroscopy and transport measurements indicate the simultaneous presence of localized and itinerant charge carriers. However, it is demonstrated that the relative amount of localized and itinerant Ti $3d$ electrons in the ground state cannot be deduced from the relative intensities of the Raman and fluorescence peaks in excitation energy dependent RIXS measurements, in contrast to previous interpretations. Rather, we attribute the observation of either the Raman or the fluorescence signal to the spatial extension of the intermediate state reached in the RIXS excitation process.Comment: 9 pages, 6 figure

Simulating the Mammalian Blastocyst - Molecular and Mechanical Interactions Pattern the Embryo

Mammalian embryogenesis is a dynamic process involving gene expression and mechanical forces between proliferating cells. The exact nature of these interactions, which determine the lineage patterning of the trophectoderm and endoderm tissues occurring in a highly regulated manner at precise periods during the embryonic development, is an area of debate. We have developed a computational modeling framework for studying this process, by which the combined effects of mechanical and genetic interactions are analyzed within the context of proliferating cells. At a purely mechanical level, we demonstrate that the perpendicular alignment of the animal-vegetal (a-v) and embryonic-abembryonic (eb-ab) axes is a result of minimizing the total elastic conformational energy of the entire collection of cells, which are constrained by the zona pellucida. The coupling of gene expression with the mechanics of cell movement is important for formation of both the trophectoderm and the endoderm. In studying the formation of the trophectoderm, we contrast and compare quantitatively two hypotheses: (1) The position determines gene expression, and (2) the gene expression determines the position. Our model, which couples gene expression with mechanics, suggests that differential adhesion between different cell types is a critical determinant in the robust endoderm formation. In addition to differential adhesion, two different testable hypotheses emerge when considering endoderm formation: (1) A directional force acts on certain cells and moves them into forming the endoderm layer, which separates the blastocoel and the cells of the inner cell mass (ICM). In this case the blastocoel simply acts as a static boundary. (2) The blastocoel dynamically applies pressure upon the cells in contact with it, such that cell segregation in the presence of differential adhesion leads to the endoderm formation. To our knowledge, this is the first attempt to combine cell-based spatial mechanical simulations with genetic networks to explain mammalian embryogenesis. Such a framework provides the means to test hypotheses in a controlled in silico environment

Effects of macroscopic polarization in III-V nitride multi-quantum-wells

Huge built-in electric fields have been predicted to exist in wurtzite III-V nitrides thin films and multilayers. Such fields originate from heterointerface discontinuities of the macroscopic bulk polarization of the nitrides. Here we discuss the background theory, the role of spontaneous polarization in this context, and the practical implications of built-in polarization fields in nitride nanostructures. To support our arguments, we present detailed self-consistent tight-binding simulations of typical nitride QW structures in which polarization effects are dominant.Comment: 11 pages, 9 figures, uses revtex/epsf. submitted to PR

Collective motion of active Brownian particles in one dimension

We analyze a model of active Brownian particles with non-linear friction and velocity coupling in one spatial dimension. The model exhibits two modes of motion observed in biological swarms: A disordered phase with vanishing mean velocity and an ordered phase with finite mean velocity. Starting from the microscopic Langevin equations, we derive mean-field equations of the collective dynamics. We identify the fixed points of the mean-field equations corresponding to the two modes and analyze their stability with respect to the model parameters. Finally, we compare our analytical findings with numerical simulations of the microscopic model.Comment: submitted to Eur. Phys J. Special Topic

Relationships among internal fat depots and subcutaneous fat in sheep.

The understanding of the relationships among the different adipose tissue depots as well as accurately predicting their masses is critical for animal growth modeling. Thus, the aims of this study were 1) to evaluate the phenotypic correlations among internal fat masses and subcutaneous fat thickness in sheep and 2) to predict the internal total fat mass using KPH fat weight and subcutaneous fat thickness information.Edição dos trabalhos do: ADSA-PSA-AMPA-ASAS-CSAS-WSASAS JOINT ANNUAL MEETING, 2012, Phoenix-AR. Small Ruminant: Production.T370

Performance and carcass traits of crossbred cattle raised in pastures supplemented or not with virginiamycin.

he aim of this study was to assess performance and carcass traits of crossbred cattle raised grazing tropical grasses, receiving supplement with or without virginiamycin (VM). Steers (n = 49) and heifers (n = 56) produced from matting Nellore, ½ Nellore x ½ Angus and ½ Nellore x ½ Caracu dams with Braford, Charbray and Caracu sires were raised grazing tropical grasses ( Brachiaria brizantha cv. Marandu) from 9 to 20 mo of age. The animals were divided into eight paddocks of eight hectares each, with care to form groups containing individuals of all genetic groups and balanced in age and average body weight (BW). During the dry season (July to October) cattle received protein supplements containing (n = 52) or not VM (n = 53), formulated for intake of 1 g kg -1 of BW and during the rainy season (November to June) cattle received mineral mixtures containing (n = 52) or not VM (n = 53). The VM was included in the supplements to provide an intake of 45 mg 100 kg -1 of BW. Supplements were provided in open troughs ad libitum and intake was evaluated by weighing monthly leftovers

Evaluation of contraceptive methods in women with congenital heart disease in Germany, Hungary and Japan

Aims For women with congenital heart defects (CHD), pregnancy may pose a health risk. Sexually active women with CHD without the desire for own children or for whom pregnancy would imply considerable health risks require adequate counselling regarding appropriate contraception. This study gathers data on the contraceptive behaviour of women with CHD from three different cultural regions. Methods and results 634 women with CHD from Germany, Hungary and Japan were surveyed regarding contraception and contraceptive methods (CM) used. The patients were divided into groups according to different criteria such as pregnancy associated cardiovascular risk or "safety" of the contraceptive methods used. 59% of the study participants had already gained experience with CM. The average age at the first time of use was 18.4 years; the German patients were significantly younger at the first time of using a CM than those from Hungary and Japan. Overall the condom was the method used the most (38%), followed by oral contraceptives (30%) and coitus interruptus (11%). The range of CM used in Japan was much smaller than that in Germany or Hungary. Unsafe contraceptives were currently, or had previously been used, by 29% of the surveyed patients (Germany: 25%, Hungary: 37%, Japan: 32%). Conclusion Most women with CHD use CM. There are differences between the participating countries. Adequate contraceptive counselling of women with CHD requires considering the individual characteristics of each patient, including potential contraindications. For choosing an appropriate CM, both the methods' "safety", as well as the maternal cardiovascular risk, are important. © 2015 Elsevier Ireland Ltd

Remodelling of human atrial K+ currents but not ion channel expression by chronic β-blockade

Chronic β-adrenoceptor antagonist (β-blocker) treatment in patients is associated with a potentially anti-arrhythmic prolongation of the atrial action potential duration (APD), which may involve remodelling of repolarising K+ currents. The aim of this study was to investigate the effects of chronic β-blockade on transient outward, sustained and inward rectifier K+ currents (ITO, IKSUS and IK1) in human atrial myocytes and on the expression of underlying ion channel subunits. Ion currents were recorded from human right atrial isolated myocytes using the whole-cell-patch clamp technique. Tissue mRNA and protein levels were measured using real time RT-PCR and Western blotting. Chronic β-blockade was associated with a 41% reduction in ITO density: 9.3 ± 0.8 (30 myocytes, 15 patients) vs 15.7 ± 1.1 pA/pF (32, 14), p < 0.05; without affecting its voltage-, time- or rate dependence. IK1 was reduced by 34% at −120 mV (p < 0.05). Neither IKSUS, nor its increase by acute β-stimulation with isoprenaline, was affected by chronic β-blockade. Mathematical modelling suggested that the combination of ITO- and IK1-decrease could result in a 28% increase in APD90. Chronic β-blockade did not alter mRNA or protein expression of the ITO pore-forming subunit, Kv4.3, or mRNA expression of the accessory subunits KChIP2, KChAP, Kvβ1, Kvβ2 or frequenin. There was no reduction in mRNA expression of Kir2.1 or TWIK to account for the reduction in IK1. A reduction in atrial ITO and IK1 associated with chronic β-blocker treatment in patients may contribute to the associated action potential prolongation, and this cannot be explained by a reduction in expression of associated ion channel subunits