CNS development under altered gravity: cerebellar glial and neuronal protein expression in rat neonates exposed to hypergravity.

The future of space exploration depends on a solid understanding of the developmental process under microgravity, specifically in relation to the central nervous system (CNS). We have previously employed a hypergravity paradigm to assess the impact of altered gravity on the developing rat cerebellum. The present study addresses the molecular mechanisms involved in the cerebellar response to hypergravity. Specifically, the study focuses on the expression of selected glial and neuronal cerebellar proteins in rat neonates exposed to hypergravity (1.5 G) from embryonic day (E)11 to postnatal day (P)6 or P9 (the time of maximal cerebellar changes) comparing them against their expression in rat neonates developing under normal gravity. Proteins were analyzed by quantitative Western blots of cerebellar homogenates; RNA analysis was performed in the same samples using quantitative PCR. Densitometric analysis of Western blots suggested a reduction in glial (glial acidic protein, GFAP) and neuronal (neuronal cell adhesion molecule, NCAM-L1, synaptophysin) proteins, but the changes in individual cerebellar proteins in hypergravity-exposed neonates appeared both age- and gender-specific. RNA analysis suggested a reduction in GFAP and synaptophysin mRNAs on P6. These data suggest that exposure to hypergravity may interfere with the expression of selected cerebellar proteins. These changes in protein expression may be involved in mediating the effect of hypergravity on the developing rat cerebellum.     

Stability analysis of parallel DC-DC converters

We develop analytic methodologies for stability analyses (using nonlinear and linear methodologies) of parallel dc-dc converters (under unsaturated and saturated operating conditions) using their switching model, discrete model (based on nonlinear map), and averaged model. We describe the approach for investigating the behavior of the stable and unstable equilibrium solutions of a parallel dc-dc converter under parametric variations and illustrate the methodology using a load-sharing dc-dc buck converter. For unsaturated operating condition, using bifurcation analysis and Floquet theory, we predict the stability boundary of the nominal solution, determine its postinstability dynamics, and investigate the dependence of the converter dynamics on its initial conditions. Subsequently, we demonstrate the differences in the predictions of the instabilities and instability boundaries using (conventional) linearized averaged (small-signal) and discrete and switching models.     

High resolution X-ray spectrum of AM Her

We present the analysis of archival Chandra high resolution X-ray spectra of AM Her. Emission lines from several hydrogen-like ions, helium-like ions, Fe-L shell transitions and Fe-K fluorescent are identified. Using the resonance, intercombination and forbidden lines of the few prominent helium-like ions, we infer a density greater than 2 × 10¹² cm⁻³ and a temperature of 2 MK for the oxygen and neon line emitting regions in the accretion column of AM Her.     

Theory of angle estimation using a multiarm spiral antenna

An analysis of angle estimation using a single aperture, multimode spiral is presented. It is demonstrated that in addition to the classical Comparison method, modern parameter estimation techniques such as Multiple Signal Classification (MUSIC) and MLM (Maximum Likelihood Method) can be applied to multimode antenna technology for angle estimation. These techniques, coupled with the advent of digital receivers make possible the elimination of the mode-forming network. Results of computer simulations show that these new approaches give lower bias and variance, and also extend coverage toward boresight compared with the traditional Comparison method     

High resolution spectroscopy of Seyfert warm absorbers with XMM-Newton

We present results from the analysis of an XMM-Newton observation of the Seyfert 1 galaxy NGC 7469, the first high resolution X-ray spectrum of this source. The Reflection Grating Spectrometer (RGS) spectrum has several narrow absorption and emission lines of O, N, C and Ne, originating from gas at a range of ionisation parameters, from log ξ1.6 to log ξ−2 (where ξ has the units erg cm s⁻¹). We demonstrate that the ionisation state of the warm emitter is consistent with that of the high-ionisation phase of the warm absorber, and compare the warm absorber in this object with those in other sources.     

Biomass recycle as a means to improve the energy efficiency of CELSS algal culture systems.

Algal cultures can be very rapid and efficient means to generate biomass and regenerate the atmosphere for closed environmental life support systems. However, as in the case of most higher plants, a significant fraction of the biomass produced by most algae cannot be directly converted to a useful food product by standard food technology procedures. This waste biomass will serve as an energy drain on the overall system unless it can be efficiently recycled without a significant loss of its energy content. We report experiments in which cultures of the algae Scenedesmus obliquus were grown in the light and at the expense of an added carbon source, which either replaced or supplemented the actinic light. As part of these experiments we tested hydrolyzed waste biomass from these same algae to determine whether the algae themselves could be made part of the biological recycling process. Results indicate that hydrolyzed algal (and plant) biomass can serve as carbon and energy sources for the growth of these algae, suggesting that the efficiency of the closed system could be significantly improved using this recycling process.     

The Need for a Wholistic Design Approach when using Gallium Arsenide Technology

The emerging Gallium Arsenide digital integrated circuit technology is rapidly becoming well enough established that designers of signal and data processors are planning its incorporation into advanced computational engines of all types. An examination of the characteristics of present and future generation GaAs integrated circuits indicates that they will emphasize moderate on-chip gate counts and high gate speeds. Complete advantage can be taken of GaAs digital technology only if traditional signal processor architectures are completely recast at the memory layout, logic design, arithmetic implementation, and system architecture levels, and if these issues are considered in combination with system, logic board, and chip layout and packaging constraints in a single integrated approach.     

On the physical state in the narrow-line region of the classical Seyfert galaxy NGC 7469

Based on the spectrophotometric data, by decomposition of the observed continuum, the power - law continuum characteristics of the central source are obtained. The behaviour of both electron temperature T_e and density n_e in the Narrow - Line Region (NLR) of NGC 7469 is discussed on the thermal and ionization equilibria calculations. T_e in NLR of the Sy1 galaxies are higher than the Sy2 ones, and the possible explanation is the lack of the dense (n_e 10¹⁰ cm⁻³) zone close to the central source in the Sy2 galaxies.     

Verification of IRI plasma temperature at great altitude by satellite data

Electron temperature data obtained aboard two satellites are compared with the IRI model. Our comparison may serve as an input to a future version of IRI. HINOTORI data show IRI90 to predict night time T_e quite well with the exception of a few peculiar phenomena, in particular a morning overshoot at height around 600 km and anomalous T_e observations of AKEBONO for the first time allowed to extend reliably the temperature profile up to − 8000km. This profile clearly depends on local time at all invariant latitudes. The data suggest strong influence of solar activity on electron temperature.