Superlens made of a metamaterial with extreme effective parameters

We propose a superlens formed by an ultra-dense array of crossed metallic wires. It is demonstrated that due to the anomalous interaction between crossed wires, the structured substrate is characterized by an anomalously high index of refraction and supports strongly confined guided modes with very short propagation wavelengths. It is theoretically proven that a planar slab of such structured material makes a superlens that may compensate for the attenuation introduced by free-space propagation and restore the subwavelength details of the source. The bandwidth of the proposed device can be quite significant since the response of the structured substrate is non-resonant. The theoretical results are fully supported by numerical simulations.Comment: Accepted for publication in Phys. Rev. B (in press

Evaluating the employment impact of a mandatory job search assistance program

This paper exploits area based piloting and age-related eligibility rules to identify treatment effects of a labor market program – the New Deal for Young People in the UK. A central focus is on substitution/displacement effects and on equilibrium wage effects. The program includes extensive job assistance and wage subsidies to employers. We find that the program significantly raised transitions to employment by about five percentage points (about 20 percent over the pre-program base). The impact is robust to a wide variety of non-experimental estimators. However we present some evidence suggesting that this effect may not be as large in the longer run

Evaluating the employment impact of a mandatory job search program

This paper exploits area-based piloting and age-related eligibility rules to identify treatment effects of a labor market program—the New Deal for Young People in the U.K. A central focus is on substitution/displacement effects and on equilibrium wage effects. The program includes extensive job assistance and wage subsidies to employers. We find that the impact of the program significantly raised transitions to employment by about 5 percentage points. The impact is robust to a wide variety of nonexperimental estimators. However, we present some evidence that this effect may not be as large in the longer run

Evaluating the employment effects of a mandatory job search program

This paper exploits area based piloting and age-related eligibility rules to identify treatment effects of a labor market program – the New Deal for Young People in the UK. A central focus is on substitution/displacement effects and on equilibrium wage effects. The program includes extensive job assistance and wage subsidies to employers. We find that the initial impact of the program significantly raised transitions to unsubsidized employment by about five percentage points. The impact is robust to a wide variety of non-experimental estimators. However we present some evidence that this effect may not be as large in the longer run

PAIRWISE VELOCITIES OF GALAXIES IN THE CFA AND SSRS2 REDSHIFT SURVEYS

(compressed version) We combine the CfA Redshift Survey (CfA2) and the Southern Sky Redshift Survey (SSRS2) to estimate the pairwise velocity dispersion of galaxies \sig12 on a scale of \sim 1 \hmpc. Both surveys are complete to an apparent magnitude limit $B(0)=15.5$. Our sample includes 12,812 galaxies distributed in a volume 1.8 \times 10^6 \hmpc3. We conclude: 1) The pairwise velocity dispersion of galaxies in the combined CfA2+SSRS2 redshift survey is \sig12=540 \kms \pm 180 \kms. Both the estimate and the variance of \sig12 significantly exceed the canonical values \sig12=340 \pm40 measured by Davis \& Peebles (1983) using CfA1. 2) We derive the uncertainty in \sig12 from the variation among subsamples with volumes on the order of $7 \times 10^5$ \hmpc3. This variation is nearly an order of magnitude larger than the formal error, 36 \kms, derived using least-squares fits to the CfA2+SSRS2 correlation function. This variation among samples is consistent with the conclusions of Mo \etal (1993) for a number of smaller surveys and with the analysis of CfA1 by Zurek \etal (1994). 3) When we remove Abell clusters with $R\ge1$ from our sample, the pairwise velocity dispersion of the remaining galaxies drops to 295 \pm 99 \kms. Thus the dominant source of variance in \sig12 is the shot noise contributed by dense virialized systems. 4) The distribution of pairwise velocities is consistent with an isotropic exponential with velocity dispersion independent of scale.Comment: 61 pages uuencoded, compressed postscript in 5 pieces. Also available in one piece at http://www.dao.nrc.ca/DAO/SCIENCE/science.htm

Spin waves in ultrathin ferromagnetic overlayers

The influence of a non-magnetic metallic substrate on the spin wave excitations in ultrathin ferromagnetic overlayers is investigated for different crystalline orientations. We show that spin wave dumping in these systems occur due to the tunneling of holes from the substrate into the overlayer, and that the spin wave energies may be considerably affected by the exchange coupling mediated by the substrate.Comment: RevTeX 4, 7 pages, 5 figures; submitted to Phys. Rev.

O mini-cavalo (Equus caballus) puruca da ilha de Marajó - Brasil.

O mini-cavalo Puruca em conservação no BAGAM - Banco de Germoplasma Animal da Amazônia Oriental constitui uma pequena população, sendo resultado do cruzamento do cavalo Marajoara com o pônei da raça francesa ?Shetland?, que foi selecionado até atingir a altura padrão de 1,18m. A Associação Brasileira de Criadores da Raça Puruca ? ABCRP cita que a raça possui inúmeras características morfológicas que o tornam um grupo diferenciado. Os animais são criados em Salvaterra, ilha de Marajó, PA. Os descritores estudados são: Altura da Cernelha (AC), Altura do Dorso (AD), Altura da Garupa (AG), Altura de Costados (ACo), Comprimento da Cabeça (CCa), Comprimento do Pescoço (CP), Comprimento Dorso-Lombo (CDL), Comprimento da Garupa (CG), Comprimento da Espádua (CE), Comprimento do Corpo (CC), Largura da Cabeça (LC), Largura do Peito (LP), Largura das Ancas (LA), Perímetro do Tórax (PT) e Perímetro da Canela (PC), além dos pesos nas idades padrões. A raça, com base em marcadores microssatélites, é uma variedade da raça Marajoara, em função de cruzamentos entre os dois grupos genéticos e seleção para o menor porte. Este trabalho apresenta resultados parciais dos principais descritores, além de avaliar o comportamento e o desempenho da raça em conservação