Longitudinal Spin Asymmetry and Cross Section of Inclusive pi0 Production in Polarized p+p Collisions at RHIC

We present the first measurement of the cross section and the double longitudinal spin asymmetry of inclusive pi0 production in polarized p+p collisions at Sqrt(s) = 200 GeV at mid-rapidity with the STAR detector, using the barrel electromagnetic calorimeter. The measured cross section is compared to NLO pQCD calculations and can provide constraints on the pion fragmentation functions. Fragmentation is studied directly by measuring the momentum fraction of pi0 in jets, a quantity that is affected by the fragmentation process and jet reconstruction effects. The double longitudinal spin asymmetry is compared to NLO pQCD calculations based on different assumptions for the gluon polarization in the nucleon to provide constraints on delta g/g. At the present level of statistics the measured asymmetry disfavors a large positive gluon polarization, but can not yet distinguish between other scenarios.Comment: 4 pages, 2 figures, submitted to the proceedings of the 17th International Spin Physics Symposium (SPIN2006), Kyoto, Japan, October 2 to 7, 200

Spectroscopic Abundances in Cool Pleiades Dwarfs and NGC 2264 Stars

We derive parameters and abundances of several elements in two cool Pleiades dwarfs, four cool NGC 2264 pre-main-sequence stars, and a probable NGC 2264 nonmember from high-resolution, moderate signal-to-noise ratio, Keck/HIRES spectra. Our Pleiades Fe abundance agrees with previous spectroscopic and photometric values of hotter stars and does not resolve the 0.3 mag distance modulus discrepancy between main-sequence fitting and Hipparcos parallaxes. Abundances of Cr-Ca-Ti-Al are subsolar, mimicking the pattern of interstellar medium abundances. While modest temperature errors may contribute, the results (particularly for Al) could suggest an association with ionization potential; such effects might be related to the Pleiades Li scatter. The cluster Fe scatter and its relation to Li scatter is discussed. Three NGC 2264 members suggest [Fe/H] = -0.15 and near-solar ratios of other elements. Mildly supersolar abundances for another object support its probable nonmembership. A fourth member exhibits an Mg-Si-Fe-Ni and Cr-Ti-Ca-Al dichotomy opposite to that of the Pleiades stars; a relation to ionization potential is again suggested. A 0.15-0.20 dex scatter or steep decline, neither well accommodated by stellar models, in the NGC 2264 Li abundances with Teff is indicated. We note the surprising presence of the λ7774 O I triplet in our Pleiades stars, one of the cool NGC 2264 stars, and the K6 field dwarf GL 241. The inferred LTE O abundances are enhanced by 0.23-0.85 dex over solar, suggesting that even non-LTE calculations of the O I triplet are incomplete and perhaps implicating the influence of an overlying chromosphere. Our results demonstrate the utility of cluster abundances besides Fe and Li in addressing fundamental issues concerning stellar evolution and systematic errors in the analysis of cool young stars

Influence of speed of sample processing on placental energetics and signalling pathways: implications for tissue collection.

INTRODUCTION: The placenta is metabolically highly active due to extensive endocrine and active transport functions. Hence, placental tissues soon become ischaemic after separation from the maternal blood supply. Ischaemia rapidly depletes intracellular ATP, and leads to activation of stress-response pathways aimed at reducing metabolic demands and conserving energy resources for vital functions. Therefore, this study aimed to elucidate the effects of ischaemia ex vivo as may occur during tissue collection on phosphorylation of placental proteins and kinases involved in growth and cell survival, and on mitochondrial complexes. METHODS: Eight term placentas obtained from normotensive non-laboured elective caesarean sections were kept at room-temperature and sampled at 10, 20, 30 and 45 min after delivery. Samples were analyzed by Western blotting. RESULTS: Between 10 and 45 min the survival signalling pathway intermediates, P-AKT, P-GSK3α and β, P-4E-BP1 and P-p70S6K were reduced by 30-65%. Stress signalling intermediates, P-eIF2α increased almost 3 fold after 45 min. However, other endoplasmic reticulum stress markers and the Heat Shock Proteins, HSP27, HSP70 and HSP90, did not change. Phosphorylation of AMPK, an energy sensor, was elevated 2 fold after 45 min. Contemporaneously, there was an ∼25% reduction in mitochondrial complex IV subunit I. DISCUSSION AND CONCLUSIONS: These results suggest that for placental signalling studies, samples should be taken and processed within 10 min of caesarean delivery to minimize the impact of ischaemia on protein phosphorylation

Liver regeneration in dogs: Morphologic and chemical changes

Forty-four percent and 72% hepatectomy were carried out in dogs and the animals were sacrificed for biochemical and pathologic studies from 0.5 to 6 days later. Compensatory hypertrophy and hyperplasia ("regeneration") were evident within 1 day, reached a maximum in 3 days, and were almost complete by 6 days. Coincident with the histologic events of regeneration were decreases in responsiveness of receptor adenyl cyclase to glucagon stimulation, increases of cyclic AMP, inconsistent changes in plasma insulin, and increases in plasma glucagon. These studies have standardized hepatic resection in dogs and they have focused attention upon some possible mechanisms that will require further study. © 1978 Academic Press, Inc. All rights of reserved

Rotational velocities of low-mass stars in the Pleiades and Hyades

We have obtained high-resolution spectra of 89 M dwarf members of the Pleiades and Hyades and have derived radial velocities, H-alpha equivalent widths, and spectroscopic rotational velocities for these stars. Typical masses of the newly-observed Pleiades and Hyades stars are ~ 0.4 M_{\sun} and ~ 0.2 M_{\sun}, respectively. We combine our new observations with previously published data to explore the rotational evolution of young stars with M < 0.4 M_\sun. The average rotation rate in the Hyades (age 600 Myr) is about 0.4 that of the Pleiades (110 Myr), and the mean equivalent widths of H-alpha are also lower. As found in previous studies, the correlation between rotation and chromospheric activity is identical in both clusters, implying that the lower activity in the Hyades is a result of the lower rotation rates. We show that a simple scaling of the Pleiades rotational distribution for M \leq 0.4 M_{\sun}, corrected for the effects of structural evolution, matches that of the Hyades if the average angular momentum loss from the Pleiades to the Hyades age is factor of \approx 6. This suggests that the distribution of initial angular momenta and disk-locking lifetimes for the lowest mass stars was similar in both clusters. We argue that this result provides further evidence for a saturation of the angular momentum loss rate at high rotational velocities.Comment: 22 pages, 11 figures, accepted for publication in The Astronomical Journal, tentatively scheduled for March 200

Spectral imaging of the central molecular zone in multiple 7-mm molecular lines

We have imaged 24 spectral lines in the central molecular zone (CMZ) around the Galactic Centre, in the range 42–50 GHz. The lines include emission from the CS, CH3OH, HC3N, SiO, HNCO, HOCO+, NH2CHO, OCS, HCS+, CCS, C34S, 13CS, 29SiO, H13CCCN, HCC13CN and HC5N molecules, and three hydrogen recombination lines. The area covered is Galactic longitude −0.7 to 1.8and latitude −0.3 to 0.2, including the bright cores around Sgr A, Sgr B2, Sgr C and G1.6-0.025. This work used the 22-m Mopra radio telescope in Australia, obtaining ~1.8 km s−1 spectral and ~ 65 arcsec spatial resolutions. We present peak images from this study and conduct a principal component analysis on the integrated emission from the brightest 10 lines, to study similarities and differences in the line distribution. We examine the integrated line intensities and line ratios in selected apertures around the bright cores, as well as for the complete mapped region of the CMZ. We compare these 7-mm lines to the corresponding lines in the 3-mm band, for five molecules, to study the excitation. There is a variation in 3 to 7-mm line ratio across the CMZ, with relatively higher ratio in the centre around Sgr B2 and Sgr A. We find that the lines are sub-thermally excited, and from modelling with RADEX find that non-Local Thermodynamic Equilibrium conditions apply, with densities of the order of 104 cm−3

Molecular line mapping of the giant molecular cloud associated with RCW 106 - II. Column density and dynamical state of the clumps

We present a fully sampled C^{18}O (1-0) map towards the southern giant molecular cloud (GMC) associated with the HII region RCW 106, and use it in combination with previous ^{13}CO (1-0) mapping to estimate the gas column density as a function of position and velocity. We find localized regions of significant ^{13}CO optical depth in the northern part of the cloud, with several of the high-opacity clouds in this region likely associated with a limb-brightened shell around the HII region G333.6-0.2. Optical depth corrections broaden the distribution of column densities in the cloud, yielding a log-normal distribution as predicted by simulations of turbulence. Decomposing the ^{13}CO and C^{18}O data cubes into clumps, we find relatively weak correlations between size and linewidth, and a more sensitive dependence of luminosity on size than would be predicted by a constant average column density. The clump mass spectrum has a slope near -1.7, consistent with previous studies. The most massive clumps appear to have gravitational binding energies well in excess of virial equilibrium; we discuss possible explanations, which include magnetic support and neglect of time-varying surface terms in the virial theorem. Unlike molecular clouds as a whole, the clumps within the RCW 106 GMC, while elongated, appear to show random orientations with respect to the Galactic plane.Comment: 17 pages, to appear in MNRA

A Survey of Volunteered Open Geo-Knowledge Bases in the Semantic Web

Over the past decade, rapid advances in web technologies, coupled with innovative models of spatial data collection and consumption, have generated a robust growth in geo-referenced information, resulting in spatial information overload. Increasing 'geographic intelligence' in traditional text-based information retrieval has become a prominent approach to respond to this issue and to fulfill users' spatial information needs. Numerous efforts in the Semantic Geospatial Web, Volunteered Geographic Information (VGI), and the Linking Open Data initiative have converged in a constellation of open knowledge bases, freely available online. In this article, we survey these open knowledge bases, focusing on their geospatial dimension. Particular attention is devoted to the crucial issue of the quality of geo-knowledge bases, as well as of crowdsourced data. A new knowledge base, the OpenStreetMap Semantic Network, is outlined as our contribution to this area. Research directions in information integration and Geographic Information Retrieval (GIR) are then reviewed, with a critical discussion of their current limitations and future prospects