High redshift AGNs from the 1Jy catalogue and the magnification bias

We have found a statistically significant (99.1 \%) excess of red ($O-E>2$) galaxies with photographic magnitudes $E<19.5$, $O< 21$ taken from the APM Sky Catalogue around $z \sim 1$ radiosources from the 1Jy catalogue. The amplitude, scale and dependence on galaxy colours of the observed overdensity are consistent with its being a result of the magnification bias caused by the weak gravitational lensing of large scale structures at redshift $z \approx 0.2-0.4$ and are hardly explained by other causes, as obscuration by dust.Comment: uuencoded file containing 3 ps files: the main text, a table and a figure. To appear in ApJ Letter

Weak lensing goes bananas: What flexion really measures

In weak gravitational lensing, the image distortion caused by shear measures the projected tidal gravitational field of the deflecting mass distribution. To lowest order, the shear is proportional to the mean image ellipticity. If the image sizes are not small compared to the scale over which the shear varies, higher-order distortions occur, called flexion. For ordinary weak lensing, the observable quantity is not the shear, but the reduced shear, owing to the mass-sheet degeneracy. Likewise, the flexion itself is unobservable. Rather, higher-order image distortions measure the reduced flexion, i.e., derivatives of the reduced shear. We derive the corresponding lens equation in terms of the reduced flexion and calculate the resulting relation between brightness moments of source and image. Assuming an isotropic distribution of source orientations, estimates for the reduced shear and flexion are obtained; these are then tested with simulations. In particular, the presence of flexion affects the determination of the reduced shear. The results of these simulations yield the amount of bias of the estimators, as a function of the shear and flexion. We point out and quantify a fundamental limitation of the flexion formalism, in terms of the product of reduced flexion and source size. If this product increases above the derived threshold, multiple images of the source are formed locally, and the formalism breaks down. Finally, we show how a general (reduced) flexion field can be decomposed into its four components: two of them are due to a shear field, carrying an E- and B-mode in general. The other two components do not correspond to a shear field; they can also be split up into corresponding E- and B-modes.Comment: 17 pages, 6 figures, submitted to A&

Comment on "Superconducting gap anisotropy vs. doping level in high-T_c cuprates" by C. Kendziora et al, PRL 77, 727 (1996)

In a recent paper Kendziora et al concluded that the superconducting gap in overdoped Bi-2212 is isotropic. From data obtained from electronic Raman scattering measurements, their conclusion was based on the observation that pair breaking peaks occured at approximately the same frequency in different scattering geometries and that the normalized scattering intensity at low energies was strongly depleted. We discuss a different interpretation of the raw data and present new data which is consistent with a strongly anisotropic gap with nodes. The spectra can be successfully described by a model for Raman scattering in a d_{x^{2}-y^{2}} superconductor with spin fluctuations and impurity scattering included.Comment: 1 page revtex plus 1 postscript figur

N-Acetylcysteine enhances cardiac HO-1 protein expression and antioxidant capacity in diabetic rats

INTRODUCTION: The antioxidant N-acetylcysteine (NAC) restores volatile anesthetic isoflurane-induced preconditioning against myocardial infarction in hyperglycemia (1). However, the mechanism whereby NAC restores isoflurane preconditioning cardioprotection is unclear. Elevated heme oxygenase-1 (HO-1) leads to improved postischaemic cardiac function in type 1 diabetes (2), and enhancement of cardiac antioxidant capacity facilitates postischemic myocardial functional recovery (3). Therefore, we hypothesized that NAC …postprin

Studies of regional and global tectonics and the rotation of the earth using very-long-baseline interferometry

Work is continuing on the study of atmospheric gradients. We include a preprint entitled 'The effect of turbulence on atmospheric gradient parameters determined from ground-based radiometric and space geodetic measurements'. Work has begun on a study of solid Earth tidal deformations using the VLBI data set. We have examined deformations at the semi-diurnal tidal period using the IRIS data set

Sleep disturbance at pre-deployment is a significant predictor of post-deployment re-experiencing symptoms.

Background: Insomnia is common in service members and associated with many mental and physical health problems. Recently, longitudinal data have been used to assess the impact of disturbed sleep on mental health outcomes. These studies have consistently shown relationships between sleep disturbance and development of mental illness. Objective: The present study examined the longitudinal relationship between sleep disturbance and PTSD symptomatology in a cohort of Marines and Navy Corpsmen deployed to Iraq and Afghanistan (n = 2,404) assessed prior to deployment, as well as at -3 and 6 months post-deployment. Additionally, we aimed to investigate the extent to which these relationships are moderated by combat-stress severity, and to what extent these findings are replicated in a second, separate cohort of Marines and Navy corpsmen (n = 938) assessed with identical measures prior to deployment and within 3 months of return. Method: The present study employed latent variable path models to examine the relationships between pre-deployment sleep disturbance and post-deployment re-experiencing symptoms. Initial cross-lagged path models were conducted on discovery and replication samples to validate the hypothesized predictive relationships. Follow up moderation path models were then conducted to include the effect of combat-stress severity on these relationships. Results: Initial cross-lagged models supported a significant relationship between pre-deployment sleep disturbance and future re-experiencing PTSD symptoms at all time points. Initial moderation models showed a small moderator effect of combat-stress severity, though the main predictive relationship between pre-deployment sleep disturbance and PTSD symptoms remained significant. The moderator effect was not significant in the replication sample. Conclusions: The results of this study support pre-deployment sleep disturbance as a risk factor for development of post-deployment PTSD symptoms. Interventions aimed at normalizing sleep may be important in preventive measures for PTSD

Infrared Spectra and Spectral Energy Distributions of Late-M- and L-Dwarfs

We have obtained 1.0-2.5um spectra at R~600 of 14 disk dwarfs with spectral types M6 to L7. For four of the dwarfs we have also obtained infrared spectra at R~3000 in narrow intervals. In addition, we present new L' photometry for four of the dwarfs in the sample, which allows improved determinations of their bolometric luminosities. We resolve the L-dwarf Denis-P J 0205-1159 into an identical pair of objects separated by 0.35". The spectra, with the published energy distribution for one other dwarf, are compared to synthetic spectra generated by upgraded model atmospheres. Good matches are found for 2200> Teff K>1900 (spectral types around M9 to L3), but discrepancies exist at Teff> 2300 K (M8) and for Teff<1800 K (L4-L7). At the higher temperatures the mismatches are due to incompleteness in the water vapor linelist. At the lower temperatures the disagreement is probably due to our treatment of dust: we assume a photospheric distribution in equilibrium with the gas phase. We derive effective temperatures for the sample from the comparison with synthetic spectra and also by comparing our observed total intrinsic luminosities to structural model calculations (which are mostly independent of the atmosphere but are dependent on the unknown masses and ages of the targets). The two derivations agree to ~200 K except for the faintest object in the sample where the discrepancy is larger. Agreement with other temperature determinations is also ~200 K, except for the L7 dwarf.Comment: 31 pages incl. 5 Tables and 12 Figures, accepted by ApJ for Feb 2001 issu

Evidence for Two Superconducting Gaps in MgB2MgB_2

We have measured the Raman spectra of polycrystalline MgB$_{2}$ from 25 {\cm} to 1200 {\cm}. When the temperature was decreased below the superconducting transition temperature $T_c$, we observed a superconductivity-induced redistribution in the electronic Raman continuum. Two pair-breaking peaks appear in the spectra, suggesting the presence of two superconducting gaps. Furthermore, we have analyzed the measured spectra using a quasi two-dimensional model in which two s-wave superconducting gaps open on two sheets of Fermi surface. For the gap values we have obtained $\Delta_1 = 22 cm^{-1}$ (2.7 meV) and $\Delta_2 = 50 cm^{-1}$ (6.2 meV). Our results suggest that a conventional phonon-mediated pairing mechanism occurs in the planar boron $\sigma$ bands and is responsible for the superconductivity of MgB$_{2}$.Comment: 3 figure