39 research outputs found
SGR J1550-5418 bursts detected with the Fermi Gamma-ray Burst Monitor during its most prolific activity
We have performed detailed temporal and time-integrated spectral analysis of
286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor
(GBM) in January 2009, resulting in the largest uniform sample of temporal and
spectral properties of SGR J1550-5418 bursts. We have used the combination of
broadband and high time-resolution data provided with GBM to perform
statistical studies for the source properties. We determine the durations,
emission times, duty cycles and rise times for all bursts, and find that they
are typical of SGR bursts. We explore various models in our spectral analysis,
and conclude that the spectra of SGR J1550-5418 bursts in the 8-200 keV band
are equally well described by optically thin thermal bremsstrahlung (OTTB), a
power law with an exponential cutoff (Comptonized model), and two black-body
functions (BB+BB). In the spectral fits with the Comptonized model we find a
mean power-law index of -0.92, close to the OTTB index of -1. We show that
there is an anti-correlation between the Comptonized Epeak and the burst
fluence and average flux. For the BB+BB fits we find that the fluences and
emission areas of the two blackbody functions are correlated. The
low-temperature BB has an emission area comparable to the neutron star surface
area, independent of the temperature, while the high-temperature blackbody has
a much smaller area and shows an anti-correlation between emission area and
temperature. We compare the properties of these bursts with bursts observed
from other SGR sources during extreme activations, and discuss the implications
of our results in the context of magnetar burst models.Comment: 13 pages, 10 figures, 2 tables; minor changes, ApJ in pres
The Swift Deep Galactic Plane Survey (DGPS) Phase-I Catalog
The \textit{Swift} Deep Galactic Plane Survey is a \textit{Swift} Key Project
consisting of 380 tiled pointings covering 40 deg of the Galactic Plane
between longitude \,\,\,\, deg and latitude
\,\, deg. Each pointing has a ks exposure, yielding a total of
1.9 Ms spread across the entire survey footprint. Phase-I observations were
carried out between March 2017 and May 2021. The Survey is complete to depth
\,\, erg s to the edge of the Galaxy. The main Survey
goal is to produce a rich sample of new X-ray sources and transients, while
also covering a broad discovery space. Here, we introduce the Survey strategy
and present a catalog of sources detected during Phase-I observations. In
total, we identify 928 X-ray sources, of which 348 are unique to our X-ray
catalog. We report on the characteristics of sources in our catalog and
highlight sources newly classified and published by the DGPS team.Comment: Submitted to ApJ
A Chirality-Based Quantum Leap
There is increasing interest in the study of chiral degrees of freedom occurring in matter and in electromagnetic fields. Opportunities in quantum sciences will likely exploit two main areas that are the focus of this Review: (1) recent observations of the chiral-induced spin selectivity (CISS) effect in chiral molecules and engineered nanomaterials and (2) rapidly evolving nanophotonic strategies designed to amplify chiral light-matter interactions. On the one hand, the CISS effect underpins the observation that charge transport through nanoscopic chiral structures favors a particular electronic spin orientation, resulting in large room-temperature spin polarizations. Observations of the CISS effect suggest opportunities for spin control and for the design and fabrication of room-temperature quantum devices from the bottom up, with atomic-scale precision and molecular modularity. On the other hand, chiral-optical effects that depend on both spin- and orbital-angular momentum of photons could offer key advantages in all-optical and quantum information technologies. In particular, amplification of these chiral light-matter interactions using rationally designed plasmonic and dielectric nanomaterials provide approaches to manipulate light intensity, polarization, and phase in confined nanoscale geometries. Any technology that relies on optimal charge transport, or optical control and readout, including quantum devices for logic, sensing, and storage, may benefit from chiral quantum properties. These properties can be theoretically and experimentally investigated from a quantum information perspective, which has not yet been fully developed. There are uncharted implications for the quantum sciences once chiral couplings can be engineered to control the storage, transduction, and manipulation of quantum information. This forward-looking Review provides a survey of the experimental and theoretical fundamentals of chiral-influenced quantum effects and presents a vision for their possible future roles in enabling room-temperature quantum technologies.ISSN:1936-0851ISSN:1936-086
Serum calcium level is related to both intima-media thickness and carotid atherosclerosis: a neglect risk factor in obese/overweight subjects
Pathology supported genetic testing and treatment of cardiovascular disease in middle age for prevention of Alzheimer’s disease
Penetration of 14C-methisoprinol into rabbit eyes with experimentally induced herpetic keratitis.
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Consistent approximate Q-conditional symmetries of PDEs: application to a hyperbolic reaction-diffusion-convection equation
Language dominance in the previously acquired languages modulates rate of third language (L3) development over time: a longitudinal study
The 894G > T (Glu298Asp) variant in the endothelial NOS gene and MTHFR polymorphisms influence homocysteine levels in patients with cognitive decline
The presence and severity of cerebrovascular pathological findings have been shown to increase the risk and stage of cognitive decline observed in Alzheimer's disease and vascular dementia. Thus, the modification of vascular risk factors seems useful to reduce the risk of dementia regardless of type. Hyperhomocysteinemia has long been known as a major independent risk factor for vascular dysfunction. In this study, we evaluated the relationships between plasma homocysteine levels and genetic risk factors for hyperhomocysteinemia, i.e., the presence of gene variants for methylenetetrahydrofolate reductase (MTHFR) and endothelial nitric oxide synthase (eNOS) in patients with cognitive impairment. Genotyping for MTHFR C677T and eNOS 894G > T polymorphisms was carried out in 69 patients with probable diagnosis of AD and anamnestic mild cognitive impairment, matched for age and gender with 69 healthy volunteers. Patients with MTHFR TT677 genotype showed higher plasma Hcy levels than controls, even after adjustment for folate levels (P < 0.05). Moreover, Hcy plasma levels were higher in cases than controls for any given eNOS genotype. In particular, the presence of eNOS TT894 genotype in patients with cognitive decline resulted significantly associated with increased plasma Hcy levels when compared with controls having the same genotype or patients having other eNOS genotypes (P = 0.02). These data suggest that both MTHFR C677T and eNOS G894T variants should be regarded as genetic risk factors for hyperhomocysteinemia in patients with cognitive decline