Ultralow threshold laser action from toroidal polymer microcavity

Cataloged from PDF version of article.We report laser action from a toroidal microcavity coated with pi-conjugated polymer. An ultralow threshold value of similar to 200 pJ/pulse is achieved by free space excitation in ambient conditions. This is the lowest threshold energy obtained in microtoroid lasers by free space excitation. The effective refractive index of the polymer, extracted from Fourier analysis of emission spectra, is 1.787, which is very close to measured value of 1.790 indicating that laser modes are located around the circumference of the cavity as whispering gallery resonances

Intergenerational persistence of health: Do immigrants get healthier as they remain in the U.S. for more generations?

AbstractIt is well known that a substantial part of income and education is passed on from parents to children, generating substantial persistence in socioeconomic status across generations. In this paper, we examine whether another form of human capital, health, is also largely transmitted from generation to generation. Using data from the NLSY, we first present new evidence on intergenerational transmission of health outcomes in the U.S., including weight, height, the body mass index (BMI), asthma and depression for both natives and immigrants. We show that between 50% and 70% of the mothers’ health status persists in both native and immigrant children, and that, on average, immigrants experience higher persistence than natives in BMI. We also find that the longer immigrants remain in the U.S., the less intergenerational persistence there is and the more immigrants look like native children. Unfortunately, the more generations immigrant families remain in the U.S., the more children of immigrants resemble natives’ higher BMI

Scattering Lens Resolves sub-100 nm Structures with Visible Light

The smallest structures that conventional lenses are able to optically resolve are of the order of 200 nm. We introduce a new type of lens that exploits multiple scattering of light to generate a scanning nano-sized optical focus. With an experimental realization of this lens in gallium phosphide we have succeeded to image gold nanoparticles at 97 nm optical resolution. Our work is the first lens that provides a resolution in the nanometer regime at visible wavelengths.Comment: 4 pages, 3 figure

Polypyrrole grafts with poly[(methyl methacrylate)-CO-(2-(N-pyrrolyl)ethyl methacrylate)]

Cataloged from PDF version of article.Conducting polymer grafts of pyrrole and poly[(methyl methacrylate)-co-(2- (N-pyrrolyl) ethyl methacrylate)] containing 0.7% PEMA units were prepared by potentiostatic anodic polymerization of pyrrole in different electrolytic media. Grafting between copolymer and pyrrole was achieved in media where tetrabutylammonium fluoroborate and sodium perchlorate were used as the supporting electrolytes. Characterizations were made by using IT-IR, DSC, TGA, SEM, CV, and elemental analysis. The conductivities of the resultant polymers seemed to be in the order of pure polypyrrole prepared under the same conditions. Copyright o 1997 Elsevier Scienc

Brieskorn manifolds as contact branched covers of spheres

We show that Brieskorn manifolds with their standard contact structures are contact branched coverings of spheres. This covering maps a contact open book decomposition of the Brieskorn manifold onto a Milnor open book of the sphere.Comment: 8 pages, 1 figur

Constructions of generalized complex structures in dimension four

Four-manifold theory is employed to study the existence of (twisted) generalized complex structures. It is shown that there exist (twisted) generalized complex structures that have more than one type change loci. In an example-driven fashion, (twisted) generalized complex structures are constructed on a myriad of four-manifolds, both simply and non-simply connected, which are neither complex nor symplectic

Synthesis and Characterization of ZnO Nanopowders and ZnO-CNT Nanocomposites Prepared by Chemical Precipitation Route

The aims of this work are synthesis of ZnO nanopowders and producing nanocomposites by mixing with carbon nanotubes. ZnO nanopowders have been synthesized by chemical precipitation route. Dierent amount of collected nanosized Zn-based precipitates and chemically oxidized carbon nanotubes powder have been mix together and annealed at 400 • C. Characterization of produced nanopowders and nanocomposites have been carried out by X-ray diractometer and scanning electron microscope

Generation of new frequencies in toroid microcavities

Microtoroid cavities with ultra high Q-factor have been fabricated using a combined process of photolithography and reflow technique for observing non-linear effects such as generation of new frequency components. For this purpose SiO2 material was used to form the toroidal cavity shape, and chalcogenide material of As2S3 maintaining very high nonlinear refractive index was thermally evaporated on top with varying thicknesses. Simulation results of the fabricated structure have exhibited new frequency components around the excitation window of 1520 nm produced by non-linear interactions. ©2008 IEEE

Intergenerational Persistence of Health in the U.S.: Do Immigrants Get Healthier as they Assimilate?

It is well known that a substantial part of income and education is passed on from parents to children, generating substantial persistence in socio-economic status across generations. In this paper, we examine whether another form of human capital, health, is also largely transmitted from generation to generation, contributing to limited socio-economic mobility. Using data from the NLSY, we first present new evidence on intergenerational transmission of health outcomes in the U.S., including weight, height, the body mass index (BMI), asthma and depression for both natives and immigrants. We show that both native and immigrant children inherit a prominent fraction of their health status from their parents, and that, on average, immigrants experience higher persistence than natives in weight and BMI. We also find that mothers’ education decreases children’s weight and BMI for natives, while single motherhood increases weight and BMI for both native and immigrant children. Finally, we find that the longer immigrants remain in the U.S., the less intergenerational persistence there is and the more immigrants look like native children. Unfortunately, the more generations immigrant families remain in the U.S., the more children of immigrants resemble natives’ higher weights, higher BMI and increased propensity to suffer from asthma