Vortex Rings in two Component Bose-Einstein Condensates

We study the structure of the vortex core in two-component Bose-Einstein condensates. We demonstrate that the order parameter may not vanish and the symmetry may not be restored in the core of the vortex. In this case such vortices can form vortex rings known as vortons in particle physics literature. In contrast with well-studied superfluid $^4He$, where similar vortex rings can be stable due to Magnus force only if they move, the vortex rings in two-component BECs can be stable even if they are at rest. This beautiful effect was first discussed by Witten in the cosmic string context, where it was shown that the stabilization occurs due to condensation of the second component of the field in the vortex core. This second condensate trapped in the core may carry a current along the vortex ring counteracting the effect of string tension that causes the loop to shrink. We speculate that such vortons may have been already observed in the laboratory. We also speculate that the experimental study of topological structures in BECs can provide a unique opportunity to study cosmology and astrophysics by doing laboratory experiments.Comment: 21 pages, 2 figure

Genomic Diversity Using Copy Number Variations in Worldwide Chicken Populations

Recently, many studies in livestock have focused on the identification of Copy Number Variants (CNVs) using high-density Single Nucleotide Polymorphism (SNP) arrays, but few have focused on studying chicken ecotypes coming from many locations. CNVs are polymorphisms, which may influence phenotype and are an important source of genetic variation in populations. The aim of this study was to explore the genetic difference and structure, using a high density SNP chip in 936 individuals from seven different countries (Brazil, Italy, Egypt, Mexico, Rwanda, Sri Lanka and Uganda). The DNA was genotyped with the Affymetrix Axiom®600k Chicken Genotyping Array and processed with stringent quality controls to obtain 559,201 SNPs in 915 individuals. The Log R Ratio (LRR) and the B Allele Frequency of SNPs were used to perform the CNV calling with PennCNV software based on a Hidden Markov Model analysis and the LRR was used to perform CNV detection with SVS Golden Helix software.After filtering, a total of 19,027 CNVs were detected with the SVS software, while 9,065 CNVs were identified with the Penn CNV software. The CNVs were summarized in 7,001 Copy Number Variant Regions (CNVRs) and 4,414 CNVRs, using the software BedTool.The consensus analysis across the CNVRs allowed the identification of 2,820 consensus CNVR, of which 1,721 were gain, 637 loss and 462 complex, for a total length of 53 Mb corresponding to the 5 % of the GalGal5 chicken autosomes. Only the consensus CNV regions obtained from both detections were considered for further analysis.The intersection analysis performed between the chicken gene database (Gallus_gallus-5.0) and the 1,927 consensus CNVRs allowed the identification (within or partial overlap) of a total of 2,354 unique genes with an official gene ID.  The CNVRs identified here represent the first comprehensive mapping in several worldwide populations, using a high-density SNP chip

Beef Feedlots In Southwestern Kansas: Local Change, Perceptions, And The Global Change Context

Cattle feedlots, some of which have a capacity of tens of thousands of head, have become a major driving force in the local economy and changing landscape of southwestern Kansas. The feedlot industry also is one of the region’s most important sources of carbonequivalent greenhouse gases. Changes to the beef industry are described, and the perceptions and attitudes of feedlot operators regarding climatic change issues and industrial change are analyzed based on a 1998 survey. The results indicate that a majority of feedlot respondents believe ‘global warming’ is mostly an unproven theory, and efforts to mitigate it are unwarranted

Optical second-harmonic investigations of the kinetics of elementary surface reactions on Si(001) and Si(111)

Resonant enhancement of optical second-harmonic generation (SHG) from silicon surfaces by dangling-bond-derived surface states makes this technique a very sensitive and versatile in situ monitor for surface coverage of hydrogen and other adsorbates. The ability to monitor hydrogen adsorption in real time allowed to distinguish between different reaction channels for dissociative adsorption of H_2 on vicinal Si(001) and Si(111) surfaces in the temperature range between 450 and 650 K. Whereas the presence of steps on Si(111) leads only to a moderate increase in reactivity, the initial sticking coefficients for step adsorption on misoriented Si(001) exceed those determined for terrace adsorption by several orders of magnitude. For double height-steps on Si(001) the values increase from 10"-"8 to 10"-"4 in the investigated temperature range from 90 to 600 K. In contrast to terrace adsorption this is a weak dependence on temperature and corresponds to an activation energy of 0.09 eV. The pronounced rise of the sticking coefficient from below 10"-"1"0 at 400 K to nearly 10"-"4 at 1000 K for the terrace sites indicates the presence of an adsorption barrier of at least 0.75 eV. Within the range of misorientations investigated the sticking coefficients attributed to terrace adsorption and their temperature dependence agree with each other and with previously reported values from the flat surface. Density functional theory calculations of Kratzer, Pehlke, and Scheffler indicate the presence of a direct adsorption path for monohydride formation, but with a dramatically reduced barrier for step adsorption due to efficient rehybridization of dangling-bond orbitals. (orig.)252 refs.Available from TIB Hannover: RN 5339(246) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

A source of high-velocity white dwarfs

SIGLEAvailable from: http://www.mpa-garching.mpg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Formation of the binary pulsars J1141-6545 and B2023+46

SIGLEAvailable from: http://www.mpa-garching.mpg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman