Scientific Findings of the Neskak Gora Project on Second Generation Immigrant Girls and Young Women from North African and South Asian Families in Europe

Research project “Neskak Gora” on discrimination against young second generation female migrants in six European countrie

Transport of interacting electrons in arrays of quantum dots and diffusive wires

We develop a detailed theoretical investigation of the effect of Coulomb interaction on electron transport in arrays of chaotic quantum dots and diffusive metallic wires. Employing the real time path integral technique we formulate a new Langevin-type of approach which exploits a direct relation between shot noise and interaction effects in mesoscopic conductors. With the aid of this approach we establish a general expression for the Fano factor of 1D quantum dot arrays and derive a complete formula for the interaction correction to the current which embraces all perturbative results previously obtained for various quasi-0D and quasi-1D disordered conductors and extends these results to yet unexplored regimes.Comment: 12 pages, 2 figure

Dark and Baryonic Matter in Bright Spiral Galaxies: I.Near-infrared and Optical Broadband Surface Photometry of 30 Galaxies

We present photometrically calibrated images and surface photometry in the B, V, R, J, H, and K-bands of 25, and in the g, r, and K-bands of 5 nearby bright (Bo_T<12.5 mag) spiral galaxies with inclinations between 30-65 degrees spanning the Hubble Sequence from Sa to Scd. Data are from The Ohio State University Bright Spiral Galaxy Survey, the Two Micron All Sky Survey, and the Sloan Digital Sky Survey Second Data Release. Radial surface brightness profiles are extracted, and integrated magnitudes are measured from the profiles. Axis ratios, position angles, and scale lengths are measured from the near-infrared images. A 1-dimensional bulge/disk decomposition is performed on the near-infrared images of galaxies with a non-negligible bulge component, and an exponential disk is fit to the radial surface brightness profiles of the remaining galaxies.Comment: 28 page

A Look At Three Different Scenarios for Bulge Formation

In this paper, we present three qualitatively different scenarios for bulge formation: a secular evolution model in which bulges form after disks and undergo several central starbursts, a primordial collapse model in which bulges and disks form simultaneously, and an early bulge formation model in which bulges form prior to disks. We normalize our models to the local z=0 observations of de Jong & van der Kruit (1994) and Peletier & Balcells (1996) and make comparisons with high redshift observations. We consider model predictions relating directly to bulge-to-disk properties. As expected, smaller bulge-to-disk ratios and bluer bulge colors are predicted by the secular evolution model at all redshifts, although uncertainties in the data are currently too large to differentiate strongly between the models.Comment: 19 pages, 6 figures, accepted for publication in the Astrophysical Journa

Split-gate quantum point contacts with tunable channel length

We report on developing split-gate quantum point contacts (QPCs) that have a tunable length for the transport channel. The QPCs were realized in a GaAs/AlGaAs heterostructure with a two- dimensional electron gas (2DEG) below its surface. The conventional design uses 2 gate fingers on the wafer surface which deplete the 2DEG underneath when a negative gate voltage is applied, and this allows for tuning the width of the QPC channel. Our design has 6 gate fingers and this provides additional control over the form of the electrostatic potential that defines the channel. Our study is based on electrostatic simulations and experiments and the results show that we developed QPCs where the effective channel length can be tuned from about 200 nm to 600 nm. Length-tunable QPCs are important for studies of electron many-body effects because these phenomena show a nanoscale dependence on the dimensions of the QPC channel

Self-Regulation of Star Formation in Low Metallicity Clouds

We investigate the process of self-regulated star formation via photodissociation of hydrogen molecules in low metallicity clouds. We evaluate the influence region's scale of a massive star in low metallicity gas clouds whose temperatures are between 100 and 10000 Kelvin. A single O star can photodissociate hydrogen molecules in the whole of the host cloud. If metallicity is smaller than about 10^{-2.5} of the solar metallicity, the depletion of coolant of the the host cloud is very serious so that the cloud cannot cool in a free-fall time, and subsequent star formation is almost quenched. On the contrary, if metallicity is larger than about 10^{-1.5} of the solar metallicity, star formation regulation via photodissociation is not efficient. The typical metallicity when this transition occurs is about 1/100 of the solar metallicity. This indicates that stars do not form efficiently before the metallicity becomes larger than about 1/100 of the solar metallicity and we considered that this value becomes the lower limit of the metallicity of luminous objects such as galaxies.Comment: 14 pages, including 5 figures, To appear in ApJ, Vol. 53

The "quasi-stable" lipid shelled microbubble in response to consecutive ultrasound pulses

Controlled microbubble stability upon exposure to consecutive ultrasound exposures is important for increased sensitivity in contrast enhanced ultrasound diagnostics and manipulation for localised drug release. An ultra high-speed camera operating at 13 × 10 6 frames per second is used to show that a physical instability in the encapsulating lipid shell can be promoted by ultrasound, causing loss of shell material that depends on the characteristics of the microbubble motion. This leads to well characterized disruption, and microbubbles follow an irreversible trajectory through the resonance peak, causing the evolution of specific microbubble spectral signatures. © 2012 American Institute of Physics

Morphological Evolution of Distant Galaxies from Adaptive Optics Imaging

We report here on a sample of resolved, infrared images of galaxies at z~0.5 taken with the 10-m Keck Telescope's Adaptive Optics (AO) system. We regularly achieve a spatial resolution of 0.05'' and are thus able to resolve both the disk and bulge components. We have extracted morphological information for ten galaxies and compared their properties to those of a local sample. The selection effects of both samples were explicitly taken into account in order to derive the unbiased result that disks at z~0.5 are ~0.6 mag arcsec^-2 brighter than, and about the same size as, local disks. The no-luminosity-evolution case is ruled out at 90% confidence. We also find, in a more qualitative analysis, that the bulges of these galaxies have undergone a smaller amount of surface brightness evolution and have also not changed significantly in size from z~0.5 to today. This is the first time this type of morphological evolution has been measured in the infrared and it points to the unique power of AO in exploring galaxy evolution.Comment: 27 pages, 7figures, 2 tables. Accepted for publication in the Astrophysical Journa