628 research outputs found
Superdeformation in Asymmetric NZ Nucleus Ar
A rotational band with five -ray transitions ranging from 2 to
12 states was identified in Ar. This band is linked through
transitions from the excited 2, 4 and 6 levels to
the low-lying states; this determines the excitation energy and the spin-parity
of the band. The deduced transition quadrupole moment of 1.45 indicates that the band has a superdeformed shape. The nature of the band
is revealed by cranked Hartree--Fock--Bogoliubov calculations and a
multiparticle--multihole configuration is assigned to the band
Higher Order Corrections to the Primordial Gravitational Wave Spectrum and its Impact on Parameter Estimates for Inflation
We study the impact of the use of the power series expression for the
primordial tensor spectrum on parameter estimation from future direct detection
gravitational wave experiments. The spectrum approximated by the power series
expansion may give large deviation from the true (fiducial) value when it is
normalized at CMB scale because of the large separation between CMB and direct
detection scales. We derive the coefficients of the higher order terms of the
expansion up to the sixth order within the framework of the slow-roll
approximation and investigate how well the inclusion of higher order terms
improves the analytic prediction of the spectrum amplitude by comparing with
numerical results. Using the power series expression, we consider future
constraints on inflationary parameters expected from direct detection
experiments of the inflationary gravitational wave background and show that the
truncation of the higher order terms can lead to incorrect evaluation of the
parameters. We present two example models; a quadratic chaotic inflation model
and mixed inflaton and curvaton model with a quartic inflaton potential.Comment: 25 pages, 7 figures, revised version accepted by JCA
Large igneous province activity drives oceanic anoxic event 2 environmental change across eastern Asia
During mid-Cretaceous Oceanic Anoxic Event 2, significant increase of atmospheric carbon dioxide concentrations from the eruption of the large igneous provinces is hypothesized to have induced a humid climate and an elevation in nutrient runoff from continents to the oceans, resulting in oxygen depletion in the ocean. However, hitherto there is limited insight into the driving factors of Oceanic Anoxic Event 2 from the Pacific and Asian continental margins, even though the former and the latter were the largest ocean and landmass at that time. Here, a multiproxy analysis for the Oceanic Anoxic Event 2 interval of the Yezo Group –deposited on northwestern Pacific along the active Asian continental margin– is interpretated to identify seven volcanic pulses, five of which may have elevated humidity, weathering intensity, and vegetational change in the eastern margin of Asia. Moreover, oxygen depletion occurred simultaneously in the northwest Pacific. Given that these environmental changes in the eastern margin of Asia were penecontemporaneous with the global carbon burial intervals during Oceanic Anoxic Event 2, the elevated nutrient supply from the Asian continental margin to the Pacific Ocean may have, in part, contributed to the worldwide depletion of oxygen of the ocean during Oceanic Anoxic Event 2
Fox-1 family of RNA-binding proteins
The Fox-1 family of RNA-binding proteins are evolutionarily conserved regulators of tissue-specific alternative splicing in metazoans. The Fox-1 family specifically recognizes the (U)GCAUG stretch in regulated exons or in flanking introns, and either promotes or represses target exons. Recent unbiased bioinformatics analyses of alternatively spliced exons and comparison of various vertebrate genomes identified the (U)GCAUG stretch as a highly conserved and widely distributed element enriched in intronic regions surrounding exons with altered inclusion in muscle, heart, and brain, consistent with specific expression of Fox-1 and Fox-2 in these tissues. Global identification of Fox-2 target RNAs in living cells revealed that many of the Fox-2 target genes themselves encode splicing regulators. Further systematic elucidation of target genes of the Fox-1 family and other splicing regulators in various tissues will lead to a comprehensive understanding of splicing regulatory networks
The Role of Bile in the Regulation of Exocrine Pancreatic Secretion
As early as 1926 Mellanby (1) was able to show that introduction of bile into the duodenum of anesthetized cats produces a copious flow of pancreatic juice. In conscious dogs, Ivy & Lueth (2) reported, bile is only a weak stimulant of pancreatic secretion. Diversion of bile from the duodenum, however, did not influence pancreatic volume secretion stimulated by a meal (3,4). Moreover, Thomas & Crider (5) observed that bile not only failed to stimulate the secretion of pancreatic juice but also abolished the pancreatic response to intraduodenally administered peptone or soap
Study of Kosterlitz-Thouless transition of Bose systems governed by a random potential using quantum Monte Carlo simulations
We perform quantum Monte Carlo simulations to study the 2D hard-core
Bose-Hubbard model in a random potential. Our motivation is to investigate the
effects of randomness on the Kosterlitz--Thouless (KT) transition. The chemical
potential is assumed to be random, by site, with a Gaussian distribution. The
KT transition is confirmed by a finite-size analysis of the superfluid density
and the power-law decay of the correlation function. By varying the variance of
the Gaussian distribution, we find that the transition temperature decreases as
the variance increases. We obtain the phase diagram showing the superfluid and
disordered phases, and estimate the quantum critical point (QCP). Our results
on the ground state reveal the existence of the Bose glass phase. Finally, we
discuss what the value of the variance at the QCP indicates from the viewpoint
of percolation.Comment: 7 pages, 9 figures, accepted for publication in JPS
Coordinated and Cohesive Movement of Two Small Conspecific Fish Induced by Eliciting a Simultaneous Optomotor Response
BACKGROUND: In animal groups such as herds, schools, and flocks, a certain distance is maintained between adjacent individuals, allowing them to move as a cohesive unit. Proximate causations of the cohesive and coordinated movement under dynamic conditions, however, have been poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: We established a novel and simple behavioral assay using pairs of small fish (medaka and dwarf pufferfish) by eliciting a simultaneous optomotor response (OMR). We demonstrated that two homospecific fish began to move cohesively and maintained a distance of 2 to 4 cm between them when an OMR was elicited simultaneously in the fish. The coordinated and cohesive movement was not exhibited under a static condition. During the cohesive movement, the relative position of the two fish was not stable. Furthermore, adult medaka exhibited the cohesive movement but larvae did not, despite the fact that an OMR could be elicited in larvae, indicating that this ability to coordinate movement develops during maturation. The cohesive movement was detected in homospecific pairs irrespective of body-color, sex, or albino mutation, but was not detected between heterospecific pairs, suggesting that coordinated movement is based on a conspecific interaction. CONCLUSIONS/SIGNIFICANCE: Our findings demonstrate that coordinated behavior between a pair of animals was elicited by a simultaneous OMR in two small fish. This is the first report to demonstrate induction of a schooling-like movement in a pair of fish by an OMR and to investigate the effect of age, sex, body color, and species on coordination between animals under a dynamic condition
Upregulation of human autophagy-initiation kinase ULK1 by tumor suppressor p53 contributes to DNA-damage-induced cell death
In yeast, activation of ATG1/ATG13 kinase complex initiates autophagy. This mechanism of autophagy initiation is conserved, as unc-51-like kinase 1 (ULK1) and unc-51-like kinase 2 (ULK2) are two mammalian functional homologues of ATG1 and form similar complex with mammalian ATG13. Here, we report that both ULK1 and ULK2 are transcriptional targets of tumor suppressor p53. In response to DNA damage, ULK1 and ULK2 are upregulated by p53. The upregulation of ULK1 (ULK2)/ATG13 complex by p53 is necessary for the sustained autophagy activity induced by DNA damage. In this context, elevated autophagy contributes to subsequent cell death. These findings suggest that ULK1 and ULK2 may mediate part of tumor suppression activity in mammalian cells and contribute to the efficacy of genotoxic chemotherapeutic drugs
Evaluation of A2BP1 as an Obesity Gene
OBJECTIVE-A genome-wide association study (GWAS) in Pima Indians (n = 413) identified variation in the ataxin-2 binding protein 1 gene (A2BP1) that was associated with percent body fat. On the basis of this association and the obese phenotype of ataxin-2 knockout mice, A2BP1 was genetically and functionally analyzed to assess its potential role in human obesity. RESEARCH DESIGN AND METHODS-Variants spanning A2BP1 were genotyped in a population-based sample of 3,234 full-heritage Pima Indians, 2,843 of whom were not part of the initial GWAS study and therefore could serve as a sample to assess replication. Published GWAS data across A2BP1 were additionally analyzed in French adult (n = 1,426) and children case/control subjects (n = 1,392) (Meyre et al. Nat Genet 2009;41:157-159). Selected variants were genotyped in two additional samples of Caucasians (Amish, n = 1,149, and German children case/control subjects, n = 998) and one additional Native American (n = 2,531) sample. Small interfering RNA was used to knockdown A2bp1 message levels in mouse embryonic hypothalamus cells. RESULTS-No single variant in A2BP1 was reproducibly associated with obesity across the different populations. However, different variants within intron 1 of A2BP1 were associated with BMI in full-heritage Pima Indians (rs10500331, P = 1.9 x 10(-7)) and obesity in French Caucasian adult (rs4786847, P = 1.9 x 10(-10)) and children (rs8054147, P = 9.2 x 10(-6)) case/control subjects. Reduction of A2bp1 in mouse embryonic hypothalamus cells decreased expression of Atxn2, Insr, and Mc4r. CONCLUSIONS-Association analysis suggests that variation in A2BP1 influences obesity, and functional studies suggest that A2BP1 could potentially affect adiposity via the hypothalamic MC4R pathway. Diabetes 59:2837-2845, 201
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