8,217 research outputs found
Superfluid-insulator transitions of two-species Bosons in an optical lattice
We consider a realization of the two-species bosonic Hubbard model with
variable interspecies interaction and hopping strength. We analyze the
superfluid-insulator (SI) transition for the relevant parameter regimes and
compute the ground state phase diagram for odd filling at commensurate
densities. We find that in contrast to the even commensurate filling case, the
superfluid-insulator transition occurs with (a) simultaneous onset of
superfluidity of both species or (b) coexistence of Mott insulating state of
one species and superfluidity of the other or, in the case of unit filling, (c)
complete depopulation of one species. The superfluid-insulator transition can
be first order in a large region of the phase diagram. We develop a variational
mean-field method which takes into account the effect of second order quantum
fluctuations on the superfluid-insulator transition and corroborate the
mean-field phase diagram using a quantum Monte Carlo study.Comment: 12 pages, 11 figure
The Distance to the Vela Supernova Remnant
We have obtained high resolution Ca II and Na I absorption line spectra
toward 68 OB stars in the direction of the Vela Supernova Remnant. The stars
lie at distances of 190 -- 2800 pc as determined by Hipparcos and spectroscopic
parallax estimations. The presence of high velocity absorption attributable to
the remnant along some of the sight lines constrains the remnant distance to
250+/-30 pc. This distance is consistent with several recent investigations
that suggest that the canonical remnant distance of 500 pc is too large.Comment: To be published in The Astrophysical Journal Letters Figure 1 y-axis
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Emotional Intelligence is a Protective Factor for Suicidal Behavior
Objective: Little is known about what factors protect against the occurrence of suicide ideation and attempts. We tested whether emotional intelligence (EI)—the ability to perceive, integrate, understand, and manage one’s emotions—decreases the likelihood of suicide ideation and attempts among those at risk. Method: Adolescents (N=54) aged 12-19 were recruited from local psychiatric clinics and the community to participate in this cross-sectional laboratory-based study. Analyses examined whether the relations between childhood sexual abuse (CSA) and suicide ideation and attempts were moderated by adolescents’ EI. These constructs were assessed using self-report, structured interviews, and performance-based tests, respectively. Results: Analyses revealed that EI is a protective factor for both suicide ideation and attempts. Specifically, CSA was strongly predictive of these outcomes among those with low EI, weakly predictive among those with medium EI, and completely unrelated among those with high EI. Follow-up analyses revealed that the protective effect of EI was driven primarily by differences in Strategic EI (i.e., ability to understand and manage emotions) but not Experiential EI (i.e., ability to perceive emotions and integrate emotions into thoughts). Conclusions: This study provides preliminary evidence that EI is a protective factor for suicide ideation and attempts. Important next steps include testing the moderating influence of EI on a wider range of stressful life events and self-injurious behaviors, as well as conducting experimental studies to determine whether enhancing EI decreases the subsequent occurrence of these behavior problems.Psycholog
Learning a Static Analyzer from Data
To be practically useful, modern static analyzers must precisely model the
effect of both, statements in the programming language as well as frameworks
used by the program under analysis. While important, manually addressing these
challenges is difficult for at least two reasons: (i) the effects on the
overall analysis can be non-trivial, and (ii) as the size and complexity of
modern libraries increase, so is the number of cases the analysis must handle.
In this paper we present a new, automated approach for creating static
analyzers: instead of manually providing the various inference rules of the
analyzer, the key idea is to learn these rules from a dataset of programs. Our
method consists of two ingredients: (i) a synthesis algorithm capable of
learning a candidate analyzer from a given dataset, and (ii) a counter-example
guided learning procedure which generates new programs beyond those in the
initial dataset, critical for discovering corner cases and ensuring the learned
analysis generalizes to unseen programs.
We implemented and instantiated our approach to the task of learning
JavaScript static analysis rules for a subset of points-to analysis and for
allocation sites analysis. These are challenging yet important problems that
have received significant research attention. We show that our approach is
effective: our system automatically discovered practical and useful inference
rules for many cases that are tricky to manually identify and are missed by
state-of-the-art, manually tuned analyzers
Spacecraft System Integration and Test: SSTI Lewis critical design audit
The Critical Design Audit package is the final detailed design package which provides a comprehensive description of the SSTI mission. This package includes the program overview, the system requirements, the science and applications activities, the ground segment development, the assembly, integration and test description, the payload and technology demonstrations, and the spacecraft bus subsystems. Publication and presentation of this document marks the final requirements and design freeze for SSTI
N_pN_n dependence of empirical formula for the lowest excitation energy of the 2^+ states in even-even nuclei
We examine the effects of the additional term of the type on the recently proposed empirical formula for the lowest excitation
energy of the states in even-even nuclei. This study is motivated by the
fact that this term carries the favorable dependence of the valence nucleon
numbers dictated by the scheme. We show explicitly that there is not
any improvement in reproducing by including the extra
term. However, our study also reveals that the excitation energies
, when calculated by the term alone (with the mass number
dependent term), are quite comparable to those calculated by the original
empirical formula.Comment: 14 pages, 5 figure
Localized ferromagnetic resonance force microscopy in permalloy-cobalt films
We report Ferromagnetic Resonance Force Microscopy (FMRFM) experiments on a
justaposed continuous films of permalloy and cobalt. Our studies demonstrate
the capability of FMRFM to perform local spectroscopy of different
ferromagnetic materials. Theoretical analysis of the uniform resonance mode
near the edge of the film agrees quantitatively with experimental data. Our
experiments demonstrate the micron scale lateral resolution in determining
local magnetic properties in continuous ferromagnetic samples.Comment: 7 pages, 3 figure
MicroRNA in autoimmunity and autoimmune diseases
MicroRNAs (miRNAs) are small conserved non-coding RNA molecules that post-transcriptionally regulate gene expression by targeting the 3′ untranslated region (UTR) of specific messenger RNAs (mRNAs) for degradation or translational repression. miRNA-mediated gene regulation is critical for normal cellular functions such as the cell cycle, differentiation, and apoptosis, and as much as one-third of human mRNAs may be miRNA targets. Emerging evidence has demonstrated that miRNAs play a vital role in the regulation of immunological functions and the prevention of autoimmunity. Here we review the many newly discovered roles of miRNA regulation in immune functions and in the development of autoimmunity and autoimmune disease. Specifically, we discuss the involvement of miRNA regulation in innate and adaptive immune responses, immune cell development, T regulatory cell stability and function, and differential miRNA expression in rheumatoid arthritis and systemic lupus erythematosus
Salt stress induced ion accumulation, ion homeostasis, membrane injury and sugar contents in salt-sensitive rice (Oryza sativa L. spp. indica) roots under isoosmotic conditions
Excess salt induced ionic and osmotic stresses that disturbed metabolism and led to reduction of plant development. Previous studies reported that sugars in stressed plants were involved in stress tolerance. However, the role of sugars in salt-stressed plants against only ionic effects is still unclear. The objective of this research was to investigate accumulation and homeostasis of ions, membrane injury, water content, growth characters and sugar contents in roots, in-response to salt stress under iso-osmotic conditions. Salt-sensitive rice, Pathumthani1 (PT1) was grown on MS culture medium for 7 days and was adjusted to salt stress under iso-osmotic conditions (-1.75 ± 0.20 MPa) by mannitol for 4 days. An increase in NaCl increased Na+ and Na+:K+ in PT1 roots leading to increased membrane injury, while the water content was decreased. Additionally, growth characters, including number, length, fresh weight and dry weight of roots, were inhibited. Sugar accumulations in PT1 roots were enhanced by increases in NaCl. The increase in Na+ was positively related to total soluble sugars, resulting in an osmotic adjustment of the membrane that maintained water availability. The accumulation of sugars in PT1 roots may be a primary salt-defense mechanism and may function as an osmotic control.Key words: Mannitol, membrane injury, oligosaccharides, sodium ion, potassium ion, sodium chloride
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