Decreased Neuron Density and Increased Glia Density in the Ventromedial Prefrontal Cortex (Brodmann Area 25) in Williams Syndrome.

Williams Syndrome (WS) is a neurodevelopmental disorder caused by a deletion of 25⁻28 genes on chromosome 7 and characterized by a specific behavioral phenotype, which includes hypersociability and anxiety. Here, we examined the density of neurons and glia in fourteen human brains in Brodmann area 25 (BA 25), in the ventromedial prefrontal cortex (vmPFC), using a postmortem sample of five adult and two infant WS brains and seven age-, sex- and hemisphere-matched typically developing control (TD) brains. We found decreased neuron density, which reached statistical significance in the supragranular layers, and increased glia density and glia to neuron ratio, which reached statistical significance in both supra- and infragranular layers. Combined with our previous findings in the amygdala, caudate nucleus and frontal pole (BA 10), these results in the vmPFC suggest that abnormalities in frontostriatal and frontoamygdala circuitry may contribute to the anxiety and atypical social behavior observed in WS

Dynamics of a nanowire superlattice in an ac electric field

With a one-band envelope function theory, we investigate the dynamics of a finite nanowire superlattice driven by an ac electric field by solving numerically the time-dependent Schroedinger equation. We find that for an ac electric field resonant with two energy levels located in two different minibands, the coherent dynamics in nanowire superlattices is much more complex as compared to the standard two-level description. Depending on the energy levels involved in the transitions, the coherent oscillations exhibit different patterns. A signature of barrier-well inversion phenomenon in nanowire superlattices is also obtained.Comment: 14 pages, 4 figure

Real space tests of the statistical isotropy and Gaussianity of the WMAP CMB data

ABRIDGED: We introduce and analyze a method for testing statistical isotropy and Gaussianity and apply it to the WMAP CMB foreground reduced, temperature maps, and cross-channel difference maps. We divide the sky into regions of varying size and shape and measure the first four moments of the one-point distribution within these regions, and using their simulated spatial distributions we test the statistical isotropy and Gaussianity hypotheses. By randomly varying orientations of these regions, we sample the underlying CMB field in a new manner, that offers a richer exploration of the data content, and avoids possible biasing due to a single choice of sky division. The statistical significance is assessed via comparison with realistic Monte-Carlo simulations. We find the three-year WMAP maps to agree well with the isotropic, Gaussian random field simulations as probed by regions corresponding to the angular scales ranging from 6 deg to 30 deg at 68% confidence level. We report a strong, anomalous (99.8% CL) dipole ``excess'' in the V band of the three-year WMAP data and also in the V band of the WMAP five-year data (99.3% CL). We notice the large scale hemispherical power asymmetry, and find that it is not highly statistically significant in the WMAP three-year data (<~ 97%) at scales l <= 40. The significance is even smaller if multipoles up to l=1024 are considered (~90% CL). We give constraints on the amplitude of the previously-proposed CMB dipole modulation field parameter. We easily detect the residual foregrounds in cross-band difference maps at rms level <~ 7 \mu K (at scales >~ 6 deg) and limit the systematical uncertainties to <~ 1.7 \mu K (at scales >~ 30 deg).Comment: 20 pages, 20 figures; more tests added; updated to match the version to be published in JCA

Asymmetrical domain wall propagation in bifurcated PMA wire structure due to the Dzyaloshinskii-Moriya interaction

Controlling domain wall (DW) motion in complex magnetic network structures is of paramount significance for the development of spin-based devices. Here, we report on the dynamics of a propagating DW in a bifurcated ferromagnetic wire with perpendicular magnetic anisotropy (PMA). The Dzyaloshinskii-Moriya interaction (DMI) in the wire structure induces a tilt angle to the injected DW, which leads to a quasi-selective propagation through the network branch. The DW tilting causes a field interval between DWs to arrive at Hall bars in the individual branches. Micromagnetic results further show that by tailoring the strength of the DMI, the control of DW dynamics in the PMA complex network structures can be achieved

Model for a Light Z' Boson

A model of a light $Z'$ boson is constructed and phenomenological bounds are derived. This $Z'$ boson arises from a very simple extension to the Standard Model, and it is constrained to be light because the vacuum expectation values which generate its mass also break the electroweak gauge group. It is difficult to detect experimentally because it couples exclusively or primarily (depending on symmetry breaking details) to second and third generation leptons. However, if the $Z'$ boson is sufficiently light, then there exists the possibility of the two-body decay $\tau \rightarrow \mu Z'$ occuring. This will provide a striking signature to test the model.Comment: 20 pages + 5 pages of figures (appended as postscipt files), LaTeX, OITS-53

Fabrication and Qualification of Coated Chip-on-Board Technology for Miniaturized Space Systems

The results of a study carried out in order to manufacture and verify the quality of chip-on-board (COB) packaging technology are presented. The COB, designed for space applications, was tested under environmental stresses, temperature cycling, and temperature-humidity-bias. Both robustness in space applications and in environmental protection on the ground-complete reliability without hermeticity were searched for. The epoxy-parylene combinations proved to be superior to other materials tested

FRET imaging of hemoglobin concentration in Plasmodium falciparum-infected red cells.

BACKGROUND: During its intraerythrocytic asexual reproduction cycle Plasmodium falciparum consumes up to 80% of the host cell hemoglobin, in large excess over its metabolic needs. A model of the homeostasis of falciparum-infected red blood cells suggested an explanation based on the need to reduce the colloid-osmotic pressure within the host cell to prevent its premature lysis. Critical for this hypothesis was that the hemoglobin concentration within the host cell be progressively reduced from the trophozoite stage onwards. METHODOLOGY/PRINCIPAL FINDINGS: The experiments reported here were designed to test this hypothesis by direct measurements of the hemoglobin concentration in live, infected red cells. We developed a novel, non-invasive method to quantify the hemoglobin concentration in single cells, based on Förster resonance energy transfer between hemoglobin molecules and the fluorophore calcein. Fluorescence lifetime imaging allowed the quantitative mapping of the hemoglobin concentration within the cells. The average fluorescence lifetimes of uninfected cohorts was 270+/-30 ps (mean+/-SD; N = 45). In the cytoplasm of infected cells the fluorescence lifetime of calcein ranged from 290+/-20 ps for cells with ring stage parasites to 590+/-13 ps and 1050+/-60 ps for cells with young trophozoites and late stage trophozoite/early schizonts, respectively. This was equivalent to reductions in hemoglobin concentration spanning the range from 7.3 to 2.3 mM, in line with the model predictions. An unexpected ancillary finding was the existence of a microdomain under the host cell membrane with reduced calcein quenching by hemoglobin in cells with mature trophozoite stage parasites. CONCLUSIONS/SIGNIFICANCE: The results support the predictions of the colloid-osmotic hypothesis and provide a better understanding of the homeostasis of malaria-infected red cells. In addition, they revealed the existence of a distinct peripheral microdomain in the host cell with limited access to hemoglobin molecules indicating the concentration of substantial amounts of parasite-exported material

Substellar companions and the formation of hot subdwarf stars

"Copyright 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics."We give a brief review over the observational evidence for close substellar companions to hot subdwarf stars. The formation of these core helium-burning objects requires huge mass loss of their red giant progenitors. It has been suggested that besides stellar companions substellar objects in close orbits may be able to trigger this mass loss. Such objects can be easily detected around hot subdwarf stars by medium or high resolution spectroscopy with an RV accuracy at the km s(-1)-level. Eclipsing systems of Vir type stick out of transit surveys because of their characteristic light curves. The best evidence that substellar objects in close orbits around sdBs exist and that they are able to trigger the required mass loss is provided by the eclipsing system SDSS J0820+0008, which was found in the course of the MUCHFUSS project. Furthermore, several candidate systems have been discovered.Final Accepted Versio

Antioxidant-mediated protective role of Hericium erinaceus (Bull.: Fr.) Pers. against oxidative damage in fibroblasts from Friedreich’s ataxia patient

Friedreich’s ataxia (FRDA) is a progressive neuromuscular disorder caused by substantial decrease of mitochondrial protein frataxin responsible for biogenesis of iron-sulphur clusters and protection from oxidative damage. In this study, we investigated the antioxidant activities of a standardized aqueous extract from fruiting bodies of Hericium erinaceus mushroom (HESAE) and its protective effects against oxidative damage induced by L-Buthionine sulfoximine (BSO) in fibroblasts derived from FRDA patient. The lactate dehydrogenase-based viability assay showed that FRDA fibroblast was sensitive to 12.5 mM BSO with a reduction of viability to 52.51 ± 13.92% after 24 h of BSO exposure. Interestingly, co-incubation with 32 mg/mL HESAE increased the viability to 85.35 ± 3.4%. Further, 12.5 mM BSO caused a decrease in the ratio of cellular reduced glutathione (GSH) to oxidised GSH (GSSG) that leads to cell death. Nevertheless, the damage was reduced by co-incubation with 32 mg/mL HESAE. Nuclear fluorescence staining revealed that 12.5 mM BSO induced cell death and the apoptosis was decreased by co-incubation with HESAE. These findings suggest the ability of HESAE in attenuating BSO-mediated cytotoxicity through maintenance of membrane integrity and optimal GSH/GSSG ratio, that are closely linked to its antioxidant activities. Further in vivo trials are highly warranted to clarify its potential benefits in management of FRDA

Consequences of local gauge symmetry in empirical tight-binding theory

A method for incorporating electromagnetic fields into empirical tight-binding theory is derived from the principle of local gauge symmetry. Gauge invariance is shown to be incompatible with empirical tight-binding theory unless a representation exists in which the coordinate operator is diagonal. The present approach takes this basis as fundamental and uses group theory to construct symmetrized linear combinations of discrete coordinate eigenkets. This produces orthogonal atomic-like "orbitals" that may be used as a tight-binding basis. The coordinate matrix in the latter basis includes intra-atomic matrix elements between different orbitals on the same atom. Lattice gauge theory is then used to define discrete electromagnetic fields and their interaction with electrons. Local gauge symmetry is shown to impose strong restrictions limiting the range of the Hamiltonian in the coordinate basis. The theory is applied to the semiconductors Ge and Si, for which it is shown that a basis of 15 orbitals per atom provides a satisfactory description of the valence bands and the lowest conduction bands. Calculations of the dielectric function demonstrate that this model yields an accurate joint density of states, but underestimates the oscillator strength by about 20% in comparison to a nonlocal empirical pseudopotential calculation.Comment: 23 pages, 7 figures, RevTeX4; submitted to Phys. Rev.