30 research outputs found
Quantum Interference Effects in Slowly Rotating NUT Space-time
General relativistic quantum interference effects in the slowly rotating NUT
space-time as the Sagnac effect and the phase shift effect of interfering
particle in neutron interferometer are considered. It was found that in the
case of the Sagnac effect the influence of NUT parameter is becoming important
due to the fact that the angular velocity of the locally non rotating observer
must be larger than one in the Kerr space-time. In the case of neutron
interferometry it is found that due to the presence of NUT-parameter an
additional term in the phase shift of interfering particle emerges. This term
can be, in principle, detected by sensitive interferometer and derived results
can be further used in experiments to detect the gravitomagnetic charge.
Finally, as an example, we apply the obtained results to the calculation of the
UCN (ultra-cold neutrons) energy level modification in the slowly rotating NUT
space-time.Comment: 11 pages, 1 figure, accepted for publication in Int. J. Mod. Phys. D;
added reference
Atom interferometer as a selective sensor of rotation or gravity
In the presence of Earth gravity and gravity-gradient forces, centrifugal and
Coriolis forces caused by the Earth rotation, the phase of the time-domain atom
interferometers is calculated with accuracy up to the terms proportional to the
fourth degree of the time separation between pulses. We considered double-loop
atom interferometers and found appropriate condition to eliminate their
sensitivity to acceleration to get atomic gyroscope, or to eliminate the
sensitivity to rotation to increase accuracy of the atomic gravimeter.
Consequent use of these interferometers allows one to measure all components of
the acceleration and rotation frequency projection on the plane perpendicular
to gravity acceleration. Atom interference on the Raman transition driving by
noncounterpropagating optical fields is proposed to exclude stimulated echo
processes which can affect the accuracy of the atomic gyroscopes. Using
noncounterpropagating optical fields allows one to get a new type of the Ramsey
fringes arising in the unidirectional Raman pulses and therefore centered at
the two-quantum line center. Density matrix in the Wigner representation is
used to perform calculations. It is shown that in the time between pulses, in
the noninertial frame, for atoms with fully quantized spatial degrees of
freedom, this density matrix obeys classical Liouville equations.Comment: 21 pages, 4 figures, extended references, discussion, and motivatio
The chemokine CXCL13 is elevated in the cerebrospinal fluid of patients with neurosyphilis
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The tenth data release of the Sloan digital sky survey: First spectroscopic data from the SDSS-iii apache point observatory galactic evolution experiment
The Sloan Digital Sky Survey (SDSS) has been in operation since 2000 April. This paper presents the tenth public data release (DR10) from its current incarnation, SDSS-III. This data release includes the first spectroscopic data from the Apache Point Observatory Galaxy Evolution Experiment (APOGEE), along with spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS) taken through 2012 July. The APOGEE instrument is a near-infrared R ~ 22,500 300-fiber spectrograph covering 1:514-1:696 ÎŒm. The APOGEE survey is studying the chemical abundances and radial velocities of roughly 100,000 red giant star candidates in the bulge, bar, disk, and halo of the Milky Way. DR10 includes 178,397 spectra of 57,454 stars, each typically observed three or more times, from APOGEE. Derived quantities from these spectra (radial velocities, effective temperatures, surface gravities, and metallicities) are also included.
DR10 also roughly doubles the number of BOSS spectra over those included in the ninth data release. DR10 includes a total of 1,507,954 BOSS spectra, comprising 927,844 galaxy spectra; 182,009 quasar spectra; and 159,327 stellar spectra, selected over 6373.2 deg2.This is an author-created, un-copyedited version of an article accepted for publication in The Astrophysical Journal Supplement Series. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0067-0049/211/2/17. The accepted version will be under embargo until the 18th March 2015
The DSIF Subunits Spt4 and Spt5 Have Distinct Roles at Various Phases of Immunoglobulin Class Switch Recombination
Class-switch recombination (CSR), induced by activation-induced cytidine deaminase (AID), can be divided into two phases: DNA cleavage of the switch (S) regions and the joining of the cleaved ends of the different S regions. Here, we show that the DSIF complex (Spt4 and Spt5), a transcription elongation factor, is required for CSR in a switch-proficient B cell line CH12F3-2A cells, and Spt4 and Spt5 carry out independent functions in CSR. While neither Spt4 nor Spt5 is required for transcription of S regions and AID, expression array analysis suggests that Spt4 and Spt5 regulate a distinct subset of transcripts in CH12F3-2A cells. Curiously, Spt4 is critically important in suppressing cryptic transcription initiating from the intronic SΌ region. Depletion of Spt5 reduced the H3K4me3 level and DNA cleavage at the Sα region, whereas Spt4 knockdown did not perturb the H3K4me3 status and S region cleavage. H3K4me3 modification level thus correlated well with the DNA breakage efficiency. Therefore we conclude that Spt5 plays a role similar to the histone chaperone FACT complex that regulates H3K4me3 modification and DNA cleavage in CSR. Since Spt4 is not involved in the DNA cleavage step, we suspected that Spt4 might be required for DNA repair in CSR. We examined whether Spt4 or Spt5 is essential in non-homologous end joining (NHEJ) and homologous recombination (HR) as CSR utilizes general repair pathways. Both Spt4 and Spt5 are required for NHEJ and HR as determined by assay systems using synthetic repair substrates that are actively transcribed even in the absence of Spt4 and Spt5. Taken together, Spt4 and Spt5 can function independently in multiple transcription-coupled steps of CSR
Analysis of Biological Features Associated with Meiotic Recombination Hot and Cold Spots in Saccharomyces cerevisiae
Meiotic recombination is not distributed uniformly throughout the genome. There are regions of high and low recombination rates called hot and cold spots, respectively. The recombination rate parallels the frequency of DNA double-strand breaks (DSBs) that initiate meiotic recombination. The aim is to identify biological features associated with DSB frequency. We constructed vectors representing various chromatin and sequence-based features for 1179 DSB hot spots and 1028 DSB cold spots. Using a feature selection approach, we have identified five features that distinguish hot from cold spots in Saccharomyces cerevisiae with high accuracy, namely the histone marks H3K4me3, H3K14ac, H3K36me3, and H3K79me3; and GC content. Previous studies have associated H3K4me3, H3K36me3, and GC content with areas of mitotic recombination. H3K14ac and H3K79me3 are novel predictions and thus represent good candidates for further experimental study. We also show nucleosome occupancy maps produced using next generation sequencing exhibit a bias at DSB hot spots and this bias is strong enough to obscure biologically relevant information. A computational approach using feature selection can productively be used to identify promising biological associations. H3K14ac and H3K79me3 are novel predictions of chromatin marks associated with meiotic DSBs. Next generation sequencing can exhibit a bias that is strong enough to lead to incorrect conclusions. Care must be taken when interpreting high throughput sequencing data where systematic biases have been documented
Desigualdades sociais, polĂticas de saĂșde e formação de mĂ©dicos, enfermeiros e dentistas no Brasil e em Portugal
Theoretical approaches to laser spectroscopy in the presence of gravitational fields
We present a general framework in which non-linear optical phenomena for an ensemble of accelerated atoms can be studied. We show the equivalence of various approaches through frame transformations. This equivalence is understood within the context of a covariant formalism which is briefly sketched. The choice of the frame, in which the atoms are not accelerated but where the light spectrum and the atomic source term are correspondingly modified, leads to the simplest calculation. It enables one to use the usual density matrix diagrams and associated rules. Explicit examples are given in the case of a sinusoidal gravitational wave. Finally a brief discussion of the signal-to-noise ratio of the sidebands induced by gravitational waves on saturation resonances is outlined.Nous prĂ©sentons un cadre thĂ©orique gĂ©nĂ©ral pour l'Ă©tude des processus d'optique non-linĂ©aire relatifs Ă un ensemble d'atomes accĂ©lĂ©rĂ©s. Nous montrons l'Ă©quivalence de diffĂ©rentes approches grĂące Ă des changements de systĂšme de rĂ©fĂ©rence. Cette Ă©quivalence est manifeste dans le cadre d'un formalisme covariant qui est briĂšvement exposĂ©. Le choix du systĂšme de rĂ©fĂ©rence dans lequel les atomes ne sont pas accĂ©lĂ©rĂ©s, mais oĂč le contenu spectral de la lumiĂšre et le terme de pompage atomique sont modifiĂ©s en consĂ©quence, conduit aux calculs les plus simples. Ce choix permet l'utilisation des diagrammes de matrice densitĂ© habituels ainsi que des rĂšgles diagrammatiques associĂ©es. Des exemples sont explicitement calculĂ©s dans le cas d'une onde de gravitation sinusoidale. Finalement, on prĂ©sente une brĂšve discussion du rapport signal sur bruit des raies latĂ©rales induites par les ondes de gravitation sur les rĂ©sonances de saturation
A quantum trampoline for ultra-cold atoms
We have observed the interferometric suspension of a free-falling Bose-Einstein condensate periodically submitted to multiple-order diffraction by a vertical 1D standing wave. This scheme permits simultaneously the compensation of gravity and coherent splitting/recombination of the matter waves. It results in high-contrast interference in the number of atoms detected at constant height. For long suspension times, multiple-wave interference is revealed through a sharpening of the fringes. We characterize our atom interferometer and use it to measure the acceleration of gravity