Sweeping a molecular Bose-Einstein condensate across a Feshbach resonance

We consider the dissociation of a molecular Bose-Einstein condensate during a magnetic-field sweep through a Feshbach resonance that starts on the molecular side of the resonance and ends on the atomic side. In particular, we determine the energy distribution of the atoms produced after the sweep. We find that the shape of the energy distribution strongly depends on the rate of the magnetic-field sweep, in a manner that is in good agreement with recent experiments.Comment: 4.2 pages, 4 figure

Trapped fermionic clouds distorted from the trap shape due to many-body effects

We present a general approach for calculating densities and other local quantities of trapped Fermi gases, when the cloud shape is distorted with respect to the trap shape due to global energy considerations. Our approach provides a consistent way to explore physics beyond the local density approximation, if this is necessary due to the distortion. We illustrate this by analyzing in detail experimentally observed distortions in an imbalanced Fermi mixture in an elongated trap. In particular, we demonstrate in that case dramatic deviations from ellipsoidal cloud shapes arising from the competition between surface and bulk energies.Comment: 4+ pages, 3 figures. Formalism for distorted trapped fermi systems + treatment of polarized fermion experiments. Version 2: slightly shortened, published versio

Experimental investigations in epitaxial growth of crystalline layers final report

Epitaxial growth of crystalline layer

Ultracold Superstrings in atomic boson-fermion mixtures

We propose a setup with ultracold atomic gases that can be used to make a nonrelativistic superstring in four spacetime dimensions. In particular, we consider for the creation of the superstring a fermionic atomic gas that is trapped in the core of a vortex in a Bose-Einstein condensate. We explain the required tuning of experimental parameters to achieve supersymmetry between the fermionic atoms and the bosonic modes describing the oscillations in the vortex position. Furthermore, we discuss the experimental consequences of supersymmetry.Comment: 4 pages, 4 figures; published versio

Development and Characterization of Monoclonal Antisperm Antibodies: Potential for Contraception

There is an expressed need to develop a greater variety of safe contraceptive methods which would find acceptance worldwide, particularly in developing countries. Immunization against spermatozoa might be such a method as judged by the accumulated evidence from studies on human females and in a number of female animal species. Two extraction techniques were used for sperm membrane antigen isolation. The first technique involved NP-40 detergent for antigen extraction from human motile sperm and the second technique employed homogenized human testis for antigen extraction. Using these immunogens, sperm membrane-specific monoclonal antibodies (MAbs) were developed. When these antisperm MAbs were subjected to evaluation against an extensive panel of human tissues, no cross-reactivity to somatic tissues was observed, but staining was seen on sperm cells in testis, caput- and cauda epididymis, and vas deferens. Four of these antisperm MAbs were against epididymal antigens, three were against seminal vesicle factors, and seven were against testis specific antigens. These evaluations indicated sperm specificity of these antibodies, fulfilling one of the important criteria for contraceptive vaccine development set forth in a World Health Organization (WHO) monoclonal antibody workshop report. The results of immunofluorescence (IF) and immunochemical staining (ICS) studies on methanol-fixed sperm indicated that these antibodies recognized antigens on the plasma membrane overlaying different regions of the sperm, i.e., acrosome, postacrosome, equatorial, midpiece, and tail. When these anti-sperm MAbs were tested on fresh, capacitated, and acrosome reacted spermatozoa, a differential reactivity with fresh sperm as compared to acrosome reacted sperm was observed. The wide species cross-reactivity of these antisperm antibodies indicated shared antigens in these species, raising the possibility of employing experimental animal models to test contraceptive vaccines. These antisperm MAbs demonstrated the multiplicity of antigens having a role in the process of fertilization. Eight of these antisperm MAbs were able to inhibit at least one sperm functional test in vitro, which satisfied another criterion for immunocontraceptive vaccine development. Since one MAb (DH22) was capable of binding to the acrosomal cap region of acrosome reacted sperm, this MAb could be used as a marker to identify acrosomal reacted sperm among the different matured stages found in a sperm population. Purification and biochemical characterization of these sperm antigens to which these antisperm MAbs were directed, would be of interest to better understand their immunocontraceptive potential

Hypoxic Culture Conditions as a Solution for Mesenchymal Stem Cell Based Regenerative Therapy

Cell-based regenerative therapies, based on in vitro propagation of stem cells, offer tremendous hope to many individuals suffering from degenerative diseases that were previously deemed untreatable. Due to the self-renewal capacity, multilineage potential, and immunosuppressive property, mesenchymal stem cells (MSCs) are considered as an attractive source of stem cells for regenerative therapies. However, poor growth kinetics, early senescence, and genetic instability during in vitro expansion and poor engraftment after transplantation are considered to be among the major disadvantages of MSC-based regenerative therapies. A number of complex inter-and intracellular interactive signaling systems control growth, multiplication, and differentiation of MSCs in their niche. Common laboratory conditions for stem cell culture involve ambient O-2 concentration (20%) in contrast to their niche where they usually reside in 2-9% O-2. Notably, O-2 plays an important role in maintaining stem cell fate in terms of proliferation and differentiation, by regulating hypoxia-inducible factor-1 (HIF-1) mediated expression of different genes. This paper aims to describe and compare the role of normoxia (20% O-2) and hypoxia (2-9% O-2) on the biology of MSCs. Finally it is concluded that a hypoxic environment can greatly improve growth kinetics, genetic stability, and expression of chemokine receptors during in vitro expansion and eventually can increase efficiency of MSC-based regenerative therapies.Article Link: http://www.hindawi.com/journals/tswj/2013/632972

Far-Field Plasmonic Resonance Enhanced Nano-Particle Image Velocimetry within a Micro Channel

In this paper, a novel far-field plasmonic resonance enhanced nanoparticle-seeded Particle Image Velocimetry (nPIV) has been demonstrated to measure the velocity profile in a micro channel. Chemically synthesized silver nanoparticles have been used to seed the flow in the micro channel. By using Discrete Dipole Approximation (DDA), plasmonic resonance enhanced light scattering has been calculated for spherical silver nanoparticles with diameters ranging from 15nm to 200nm. Optimum scattering wavelength is specified for the nanoparticles in two media: water and air. The diffraction-limited plasmonic resonance enhanced images of silver nanoparticles at different diameters have been recorded and analyzed. By using standard PIV techniques, the velocity profile within the micro channel has been determined from the images.Comment: submitted to Review of Scientific Instrument