1,227 research outputs found
Enhanced velocity overshoot and transconductance in Si/Si(0.64)Ge(0.36)/Si pMOSFETs - predictions for deep submicron devices
No abstract avaliable
Probing the Nature of Short Swift Bursts via Deep INTEGRAL Monitoring of GRB 050925
We present results from Swift, XMM-Newton, and deep INTEGRAL monitoring in
the region of GRB 050925. This short Swift burst is a candidate for a newly
discovered soft gamma-ray repeater (SGR) with the following observational burst
properties: 1) galactic plane (b=-0.1 deg) localization, 2) 150 msec duration,
and 3) a blackbody rather than a simple power-law spectral shape (with a
significance level of 97%). We found two possible X-ray counterparts of GRB
050925 by comparing the X-ray images from Swift XRT and XMM-Newton. Both X-ray
sources show the transient behavior with a power-law decay index shallower than
-1. We found no hard X-ray emission nor any additional burst from the location
of GRB 050925 in ~5 Ms of INTEGRAL data. We discuss about the three BATSE short
bursts which might be associated with GRB 050925, based on their location and
the duration. Assuming GRB 050925 is associated with the H II regions (W 58) at
the galactic longitude of l=70 deg, we also discuss the source frame properties
of GRB 050925.Comment: 13 pages, 13 figures, accepted for publication in ASR special issue
on Neutron Stars and Gamma Ray Bursts, full resolution of Fig 5 is available
at
http://asd.gsfc.nasa.gov/Takanori.Sakamoto/GRB050925/integral_ibis_images.ep
Cooling and the SU(2) Instanton Vaccuum
We present results of an investigation into the nature of instantons in
4-dimensional pure gauge lattice \ obtained from configurations which
have been cooled using an under-relaxed cooling algorithm. We discuss ways of
calibrating the cooling and the effects of different degrees of cooling, and
compare our data for the shapes, sizes and locations of instantons with
continuum results. In this paper we extend the ideas and techniques developed
by us for use in , and compare the results with those obtained by other
groups.Comment: 22 pages, LaTeX, uuencoded compressed tarfile of figures sent
separately. Full (compressed) postscript version (118k)available from
ftp://rock.helsinki.fi/pub/preprints/tft/Year1995/HU-TFT-95-21/paper.ps.
Action-gradient-minimizing pseudo-orbits and almost-invariant tori
Transport in near-integrable, but partially chaotic,
degree-of-freedom Hamiltonian systems is blocked by invariant tori and is
reduced at \emph{almost}-invariant tori, both associated with the invariant
tori of a neighboring integrable system. "Almost invariant" tori with rational
rotation number can be defined using continuous families of periodic
\emph{pseudo-orbits} to foliate the surfaces, while irrational-rotation-number
tori can be defined by nesting with sequences of such rational tori. Three
definitions of "pseudo-orbit," \emph{action-gradient--minimizing} (AGMin),
\emph{quadratic-flux-minimizing} (QFMin) and \emph{ghost} orbits, based on
variants of Hamilton's Principle, use different strategies to extremize the
action as closely as possible. Equivalent Lagrangian (configuration-space
action) and Hamiltonian (phase-space action) formulations, and a new approach
to visualizing action-minimizing and minimax orbits based on AGMin
pseudo-orbits, are presented.Comment: Accepted for publication in a special issue of Communications in
Nonlinear Science and Numerical Simulation (CNSNS) entitled "The mathematical
structure of fluids and plasmas : a volume dedicated to the 60th birthday of
Phil Morrison
Kappa-symmetric deformations of M5-brane dynamics
We calculate the first supersymmetric and kappa-symmetric derivative
deformation of the M5-brane worldvolume theory in a flat eleven-dimensional
background. By applying cohomological techniques we obtain a deformation of the
standard constraint of the superembedding formalism. The first possible
deformation of the constraint and hence the equations of motion arises at cubic
order in fields and fourth order in a fundamental length scale . The
deformation is unique up to this order. In particular this rules out any
induced Einstein-Hilbert terms on the worldvolume. We explicitly calculate
corrections to the equations of motion for the tensor gauge supermultiplet.Comment: 17 pages. Additional comments in section
Thermal Conductivity of Isotopically Enriched 28Si Revisited
The thermal conductivity of isotopically enriched 28Si (enrichment better
than 99.9%) was redetermined independently in three laboratories by high
precision experiments on a total of 4 samples of different shape and degree of
isotope enrichment in the range from 5 to 300 K with particular emphasis on the
range near room temperature. The results obtained in the different laboratories
are in good agreement with each other. They indicate that at room temperature
the thermal conductivity of isotopically enriched 28Si exceeds the thermal
conductivity of Si with a natural, unmodified isotope mixture by 102 %.
This finding is in disagreement with an earlier report by Ruf et al. At
26 K the thermal conductivity of 28Si reaches a maximum. The maximum
value depends on sample shape and the degree of isotope enrichment and exceeds
the thermal conductivity of natural Si by a factor of 8 for a 99.982%
28Si enriched sample. The thermal conductivity of Si with natural isotope
composition is consistently found to be 3% lower than the values
recommended in the literature
Prepregnancy Diabetes and Breastfeeding Cessation among Black Women in the United States
The incidence of diabetes is rising, and with it, the number of pregnancies affected by diabetes. U.S. black women have a disproportionately high prevalence of diabetes and lower rates of breastfeeding. Objective: The objective of this study was to quantify the relationship between diabetes before pregnancy and breastfeeding duration among black women in the United States. Materials and Methods: We analyzed women from the Black Women's Health Study (N = 59,000) to assess the relationship between prepregnancy diabetes and time to breastfeeding cessation occurring up to 24 months postdelivery using Kaplan-Meier survival curves, log rank tests, and Cox proportional hazards models. The study population included primiparous women with births between 1995 and 2009 (N = 3,404). Obesity, hypertension before pregnancy, and family history of diabetes were examined for effect modification. Results: Survival curves demonstrated a markedly reduced duration of breastfeeding in women who had been diagnosed with prepregnancy diabetes (p < 0.01). The hazard ratio for breastfeeding cessation for women with prepregnancy diabetes was 1.5 (95% confidence interval 1.1-2.0) compared with women without prepregnancy diabetes after control for age, body mass index (BMI) at age 18, prepregnancy BMI, other metabolic factors, demographics, and health behaviors. Conclusions: Our results suggest that prepregnancy diabetes is a strong predictor of curtailed breastfeeding duration, even after control for BMI. This underscores the need for targeted lactation support for diabetic women
Distinctive diets of eutherian predators in Australia
Introduction of the domestic cat and red fox has devastated Australian native fauna. We synthesized Australian diet analyses to identify traits of prey species in cat, fox and dingo diets, which prey were more frequent or distinctive to the diet of each predator, and quantified dietary overlap. Nearly half (45%) of all Australian terrestrial mammal, bird and reptile species occurred in the diets of one or more predators. Cat and dingo diets overlapped least (0.64 ± 0.27, n = 24 location/time points) and cat diet changed little over 55 years of study. Cats were more likely to have eaten birds, reptiles and small mammals than foxes or dingoes. Dingo diet remained constant over 53 years and constituted the largest mammal, bird and reptile prey species, including more macropods/potoroids, wombats, monotremes and bandicoots/bilbies than cats or foxes. Fox diet had greater overlap with both cats (0.79 ± 0.20, n = 37) and dingoes (0.73 ± 0.21, n = 42), fewer distinctive items (plant material, possums/gliders) and significant spatial and temporal heterogeneity over 69 years, suggesting the opportunity for prey switching (especially of mammal prey) to mitigate competition. Our study reinforced concerns about mesopredator impacts upon scarce/threatened species and the need to control foxes and cats for fauna conservation. However, extensive dietary overlap and opportunism, as well as low incidence of mesopredators in dingo diets, precluded resolution of the debate about possible dingo suppression of foxes and cats
Dissociable cognitive impairments in two strains of transgenic Alzheimer\u27s disease mice revealed by a battery of object-based tests
Object recognition tasks detect cognitive deficits in transgenic Alzheimer\u27s disease (AD) mouse models. Object recognition, however, is not a unitary process, and there are many uncharacterized facets of object processing with relevance to AD. We therefore systematically evaluated object processing in 5xFAD and 3xTG AD mice to clarify the nature of object recognition-related deficits. Twelve-month-old male and female 5xFAD and 3xTG mice were assessed on tasks for object identity recognition, spatial recognition, and multisensory object perception. Memory and multisensory perceptual impairments were observed, with interesting dissociations between transgenic AD strains and sex that paralleled neuropathological changes. Overreliance on the widespread object recognition task threatens to slow discovery of potentially significant and clinically relevant behavioural effects related to this multifaceted cognitive function. The current results support the use of carefully designed object-based test batteries to clarify the relationship between object recognition impairments and specific aspects of AD pathology in rodent models
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