408,241 research outputs found
ratios in relativistic heavy-ion collisions
We study ratios as a function of centrality (participant nucleon
number), transverse mass (), and rapidity, in heavy-ion collisions at beam
energies between 1A and 2A GeV. We use the relativistic transport model that
includes expicitly the strangeness degrees of freedom and consider two
scenarios for kaon properties in dense matter, one with and one without medium
modifications of their properties. In both scenarios, The ratio does
not change very much with the centrality, while the and
ratios increase with increasing centrality. Significant differences are
predicted, both in magnitudes and shapes, for the spectra and rapidity
distributions of ratio. Experimental measurement of these ratios,
currently under investigation by the FOPI, KaoS, E866, and E895 collaborations,
will be useful in revealing the kaon in-medium properties.Comment: RevTex, 10 pages, including 17 postscript figures, submitted to Phys.
Rev.
Conversion of K-Rb mixtures into stable molecules
We study the conversion of K and Rb atoms into stable molecules
through the stimulated Raman adiabatic passage (STIRAP) in photoassociation
assisted with Feshbach resonance. Starting with the mean-field Langrange
density, we show that the atom-to-molecule conversion efficiency by STIRAP
aided by Feshbach resonance is much larger than that by bare Feshbach
resonance. We also study the influence of the population imbalance on the
atom-to-molecule conversion.Comment: Revtex, 5 pages, 3 figures; version to appear in PRA (some content
changed
Using Microsatellites to Assess Genetic Variation in a Selective Breeding Program of Chinese Bay Scallop (Argopecten irradians irradians)
This study aimed to improve our understanding of the genetics of the Chinese bay scallop (Argopecten irradians irradians), one of the most important maricultured shellfish in China. Ten polymorphic microsatellite loci were examined to assess the allelic diversity, heterozygosity, and genetic variation between two domesticated populations selected for fast growth in breeding programs, and their base population. Forty-one alleles were found throughout the loci and the mean number of alleles per locus ranged 3.30-3.50. The average heterozygosity ranged 0.38-0.45, whereas the polyamorphic information content ranged 0.1504-0.7518. Genetic differences between the three populations were detected based on the number of alleles per locus, effective number of alleles, Shannon index, inbreeding coefficient (Fis), p values, genetic distance, and pairwise Fst values. There was no significant loss of genetic variability in the breeding program but changes in gene frequencies were detectable over the populations, implying that thea loci were saffected by the pressures of selective culture
Dynamical decoupling of superconducting qubits
We show that two superconducting qubits interacting via a fixed transversal
coupling can be decoupled by appropriately-designed microwave feld excitations
applied to each qubit. This technique is useful for removing the effects of
spurious interactions in a quantum processor. We also simulate the case of a
qubit coupled to a two-level system (TLS) present in the insulating layer of
the Josephson junction of the qubit. Finally, we discuss the qubit-TLS problem
in the context of dispersive measurements, where the qubit is coupled to a
resonator.Comment: 4 figures, 6 page
On the accuracy of the S/N estimates obtained with the exposure time calculator of the Wide Field Planetary Camera 2 on board the Hubble Space Telescope
We have studied the accuracy and reliability of the exposure time calculator
(ETC) of the Wide Field Planetary Camera 2 (WFPC2) on board the Hubble Space
Telescope (HST) with the objective of determining how well it represents actual
observations and, therefore, how much confidence can be invested in it and in
similar software tools. We have found, for example, that the ETC gives, in
certain circumstances, very optimistic values for the signal-to-noise ratio
(SNR) of point sources. These values overestimate by up to a factor of 2 the
HST performance when simulations are needed to plan deep imaging observations,
thus bearing serious implications on observing time allocation. For this
particular case, we calculate the corrective factors to compute the appropriate
SNR and detection limits and we show how these corrections vary with field
crowding and sky background. We also compare the ETC of the WFPC2 with a more
general ETC tool, which takes into account the real effects of pixel size and
charge diffusion. Our analysis indicates that similar problems may afflict
other ETCs in general showing the limits to which they are bound and the
caution with which their results must be taken.Comment: 14 pages, 13 figures, to be published in PASP on July 200
- âŠ