An efficient approximate factorization implicit scheme for the equations of gasdynamics

An efficient implicit finite-difference algorithm for the gas dynamic equations utilizing matrix reduction techniques is presented. A significant reduction in arithmetic operations is achieved while maintaining the same favorable stability characteristics and generality found in the Beam and Warming approximate factorization algorithm. Steady-state solutions to the conservative Euler equations in generalized coordinates are obtained for transonic flows about a NACA 0012 airfoil. The theoretical extension of the matrix reduction technique to the full Navier-Stokes equations in Cartesian coordinates is presented in detail. Linear stability, using a Fourier stability analysis, is demonstrated and discussed for the one-dimensional Euler equations. It is shown that the method offers advantages over the conventional Beam and Warming scheme and can retrofit existing Beam and Warming codes with minimal effort

Formation mechanism of the O-induced added-row reconstruction on Ag(110): A low-temperature STM study

The formation of the O-induced added-row reconstruction on Ag(110) was studied by scanning tunneling microscopy at 190 K. At this temperature critical surface processes are slow enough to be followed on the atomic scale. Ag atoms, which are required for the formation of the reconstruction, detach from steps in a row-wise fashion, starting from kink sites. The growth rate of the added rows is constant and controlled by the detachment rate of Ag atoms from the steps. The data provide evidence for a reconstruction mechanism in which the release of the metal atoms from the steps and the formation of lateral oxygen metal bonds are independent processes

Model for Cumulative Solar Heavy Ion Energy and Linear Energy Transfer Spectra

A probabilistic model of cumulative solar heavy ion energy and LET spectra is developed for spacecraft design applications. Spectra are given as a function of confidence level, mission time period during solar maximum and shielding thickness. It is shown that long-term solar heavy ion fluxes exceed galactic cosmic ray fluxes during solar maximum for shielding levels of interest. Cumulative solar heavy ion fluences should therefore be accounted for in single event effects rate calculations and in the planning of space missions

Transient and Highly Polarized Double-Peaked H-alpha Emission in the Seyfert 2 Nucleus of NGC 2110

We have discovered an extremely broad, double-peaked H-alpha emission line in the polarized flux spectrum of NGC 2110, establishing that this well-studied Seyfert 2 galaxy contains a disk-like hidden broad-line region (BLR). Several properties of NGC 2110 suggest that it is an obscured twin of Arp 102B, the prototypical double-peaked emission-line active galactic nucleus (AGN). A comparison between our data and previous spectra of NGC 2110 indicates that the double-peaked H-alpha feature is transient. The presence of a disk-like BLR in NGC 2110 has important implications for AGNs: it expands the range of properties exhibited by Seyfert 2 galaxies, and the fact that the BLR is obscured by a torus-like structure provides the first evidence that double-peaked emitters and classical Seyfert nuclei may have the same basic parsec-scale geometry.Comment: 5 pages, including 3 postscript figures. Uses emulateapj. Accepted for publication in ApJ Letter

Direct observation of mobility and interactions of oxygen molecules chemisorbed on the Ag(110) surface

The energetics of thermal motions and interactions of oxygen molecules chemisorbed on a Ag(110) surface were investigated by scanning tunneling microscopy at 60–100 K. Surface mobility is anisotropic, preferably in the [1̅10] direction with an activation energy of 0.22±0.05 eV and a preexponential factor of 1×1013±3 s−1. Along the [1̅10] direction a repulsive interaction between nearest neighbors of about 0.02 eV and an attraction of 0.04±0.01 eV between next nearest neighbors were derived. Along [001] appreciable repulsion exists between nearest neighbors, while a ''diagonal'' arrangement of molecules is associated with an attraction of 0.02±0.01 eV. The data are indicative for the operation of indirect, substrate-mediated molecule-molecule interactions

Policy Recommendations for Meeting the Grand Challenge to Stop Family Violence

This brief was created forSocial Innovation for America’s Renewal, a policy conference organized by the Center for Social Development in collaboration with the American Academy of Social Work & Social Welfare, which is leading theGrand Challenges for Social Work initiative to champion social progress. The conference site includes links to speeches, presentations, and a full list of the policy briefs

The current prevalence of child sexual abuse worldwide: a systematic review and meta-analysis

Objectives: Systematic reviews on prevalence estimates of child sexual abuse (CSA) worldwide included studies with adult participants referring on a period of abuse of about 50years. Therefore we aimed to describe the current prevalence of CSA, taking into account geographical region, type of abuse, level of country development and research methods. Methods: We included studies published between 2002 and 2009 that reported CSA in children below 18years. We performed a random effects meta-analysis and analyzed moderator variables by meta-regression. Results: Fifty-five studies from 24 countries were included. According to four predefined types of sexual abuse, prevalence estimates ranged from 8 to 31% for girls and 3 to 17% for boys. Nine girls and 3 boys out of 100 are victims of forced intercourse. Heterogeneity between primary studies was high in all analyses. Conclusions: Our results based on most recent data confirm results from previous reviews with adults. Surveys in children offer most recent estimates of CSA. Reducing heterogeneity between studies might be possible by standardized measures to make data more meaningful in international comparison

Validation of the inverted adsorption structure for free-base tetraphenyl porphyrin on Cu(111)

Utilising normal incidence X-ray standing waves we rigourously scrutinise the “inverted model” as the adsorption structure of free-base tetraphenyl porphyrin on Cu(111). We demonstrate that the iminic N atoms are anchored at near-bridge adsorption sites on the surface displaced laterally by 1.1 ± 0.2 Å in excellent agreement with previously published calculations