12,164 research outputs found
The Resistivity of Microorganisms to Thermal Inactivation by Dry Heat Final Report
Microorganism resistivity to thermal inactivation by dry heat - glass fibers and membrane filter
Spatial Corrections of ROSAT HRI Observations
X-ray observations with the ROSAT High Resolution Imager (HRI) often have
spatial smearing on the order of 10 arcsec (Morse 1994). This degradation of
the intrinsic resolution of the instrument (5 arcsec) can be attributed to
errors in the aspect solution associated with the wobble of the space craft or
with the reacquisition of the guide stars. We have developed a set of IRAF/PROS
and MIDAS/EXSAS routines to minimize these effects. Our procedure attempts to
isolate aspect errors that are repeated through each cycle of the wobble. The
method assigns a 'wobble phase' to each event based on the 402 second period of
the ROSAT wobble. The observation is grouped into a number of phase bins and a
centroid is calculated for each sub-image. The corrected HRI event list is
reconstructed by adding the sub-images which have been shifted to a common
source position. This method has shown approx. 30% reduction of the full width
half maximum (FWHM) of an X-ray observation of the radio galaxy 3C 120.
Additional examples are presented.Comment: AandA latex (6 pages with 7 embedded postscript figures). Scheduled
for publication in the 1 Dec issue of Astron. Astrophys. Suppl. Serie
Possible detection of singly-ionized oxygen in the Type Ia SN 2010kg
We present direct spectroscopic modeling of 11 high-S/N observed spectra of
the Type Ia SN 2010kg, taken between -10 and +5 days with respect to B-maximum.
The synthetic spectra, calculated with the SYN++ code, span the range between
4100 and 8500 \r{A}. Our results are in good agreement with previous findings
for other Type Ia SNe. Most of the spectral features are formed at or close to
the photosphere, but some ions, like Fe II and Mg II, also form features at
~2000 - 5000 km s above the photosphere. The well-known high-velocity
features of the Ca II IR-triplet as well as Si II 6355 are also
detected.
The single absorption feature at ~4400 \r{A}, which usually has been
identified as due to Si III, is poorly fit with Si III in SN 2010kg. We find
that the fit can be improved by assuming that this feature is due to either C
III or O II, located in the outermost part of the ejecta, ~4000 - 5000 km
s above the photosphere. Since the presence of C III is unlikely,
because of the lack of the necessary excitation/ionization conditions in the
outer ejecta, we identify this feature as due to O II. The simultaneous
presence of O I and O II is in good agreement with the optical depth
calculations and the temperature distribution in the ejecta of SN 2010kg. This
could be the first identification of singly ionized oxygen in a Type Ia SN
atmosphere.Comment: Submitted to MNRA
Multidimensional optical fractionation with holographic verification
The trajectories of colloidal particles driven through a periodic potential
energy landscape can become kinetically locked in to directions dictated by the
landscape's symmetries. When the landscape is realized with forces exerted by a
structured light field, the path a given particle follows has been predicted to
depend exquisitely sensitively on such properties as the particle's size and
refractive index These predictions, however, have not been tested
experimentally. Here, we describe measurements of colloidal silica spheres'
transport through arrays of holographic optical traps that use holographic
video microscopy to track individual spheres' motions in three dimensions and
simultaneously to measure each sphere's radius and refractive index with
part-per-thousand resolution. These measurements confirm previously untested
predictions for the threshold of kinetically locked-in transport, and
demonstrate the ability of optical fractionation to sort colloidal spheres with
part-per-thousand resolution on multiple characteristics simultaneously.Comment: 4 pages, 2 figures. Accepted for publication in Physical Review
Letter
Programmable telemetry system Patent
Time division multiplexed telemetry transmitting system controlled by programmed memor
Searching for the expelled hydrogen envelope in Type I supernovae via late-time H-alpha emission
We report the first results from our long-term observational survey aimed at
discovering late-time interaction between the ejecta of hydrogen-poor Type I
supernovae and the hydrogen-rich envelope expelled from the progenitor star
several decades/centuries before explosion. The expelled envelope, moving with
a velocity of ~10 -- 100 km s, is expected to be caught up by the
fast-moving SN ejecta several years/decades after explosion depending on the
history of the mass-loss process acting in the progenitor star prior to
explosion. The collision between the SN ejecta and the circumstellar envelope
results in net emission in the Balmer-lines, especially in H-alpha. We look for
signs of late-time H-alpha emission in older Type Ia/Ibc/IIb SNe having
hydrogen-poor ejecta, via narrow-band imaging. Continuum-subtracted H-alpha
emission has been detected for 13 point sources: 9 SN Ibc, 1 SN IIb and 3 SN Ia
events. Thirty-eight SN sites were observed on at least two epochs, from which
three objects (SN 1985F, SN 2005kl, SN 2012fh) showed significant temporal
variation in the strength of their H-alpha emission in our DIAFI data. This
suggests that the variable emission is probably not due to nearby H II regions
unassociated with the SN, and hence is an important additional hint that
ejecta-CSM interaction may take place in these systems. Moreover, we
successfully detected the late-time H-alpha emission from the Type Ib SN 2014C,
which was recently discovered as a strongly interacting SN in various (radio,
infrared, optical and X-ray) bands.Comment: 8 pages, 7 figures, accepted in Ap
Reproductive Coercion and Relationship Abuse Among Adolescents and Young Women Seeking Care at School Health Centers.
ObjectiveTo investigate demographic differences and evaluate how reproductive coercion and relationship abuse influences young females' care-seeking and sexual health behaviors.MethodsWe conducted a secondary analysis of cross-sectional baseline survey data from sexually active female students (aged 14-19 years) who sought care from school health centers. Outcomes included recent (previous 3 months) reproductive coercion, physical or sexual adolescent relationship abuse, and nonpartner sexual violence victimization. Cluster-adjusted χ tests compared demographics and generalized linear mixed models estimated associations among reproductive coercion, adolescent relationship abuse (physical and sexual abuse in romantic relationships), and care-seeking and sexual health behaviors.ResultsOf 550 sexually active high school females, 12% reported recent reproductive coercion and 17% reported physical or sexual adolescent relationship abuse, with no significant demographic differences. Prevalence of recent nonpartner sexual violence was 17%. There were no observed significant differences in care-seeking behaviors among those with recent reproductive coercion compared with those without. Physical or sexual adolescent relationship abuse was associated with increased odds of seeking testing or treatment for sexually transmitted infections (adjusted odds ratio [aOR] 2.08, 95% CI 1.05-4.13). Females exposed to both adolescent relationship abuse and reproductive coercion had higher odds of having a partner who was 5 or more years older (aOR 4.66, 95% CI 1.51-14.4), having two or more recent sexual partners (aOR 3.86, 95% CI 1.57-9.48), and using hormonal contraception only (aOR 3.77, 95% CI 1.09-13.1 vs hormonal methods with condoms).ConclusionAlmost one in eight females experienced recent reproductive coercion. We did not observe significant demographic differences in reproductive coercion. Partner age and number of sexual partners may elevate risk for abusive relationships. Relationship abuse is prevalent among high school students seeking care, with no clear pattern for case identification. By failing to identify factors associated with harmful partner behaviors, our results support universal assessment for reproductive coercion and relationship abuse among high school-aged adolescents, involving education, resources, and harm-reduction counseling to all patients.Clinical trial registrationClinicalTrials.gov, NCT01678378
Nonlocal Phases of Local Quantum Mechanical Wavefunctions in Static and Time-Dependent Aharonov-Bohm Experiments
We show that the standard Dirac phase factor is not the only solution of the
gauge transformation equations. The full form of a general gauge function (that
connects systems that move in different sets of scalar and vector potentials),
apart from Dirac phases also contains terms of classical fields that act
nonlocally (in spacetime) on the local solutions of the time-dependent
Schr\"odinger equation: the phases of wavefunctions in the Schr\"odinger
picture are affected nonlocally by spatially and temporally remote magnetic and
electric fields, in ways that are fully explored. These contributions go beyond
the usual Aharonov-Bohm effects (magnetic or electric). (i) Application to
cases of particles passing through static magnetic or electric fields leads to
cancellations of Aharonov-Bohm phases at the observation point; these are
linked to behaviors at the semiclassical level (to the old Werner & Brill
experimental observations, or their "electric analogs" - or to recent reports
of Batelaan & Tonomura) but are shown to be far more general (true not only for
narrow wavepackets but also for completely delocalized quantum states). By
using these cancellations, certain previously unnoticed sign-errors in the
literature are corrected. (ii) Application to time-dependent situations
provides a remedy for erroneous results in the literature (on improper uses of
Dirac phase factors) and leads to phases that contain an Aharonov-Bohm part and
a field-nonlocal part: their competition is shown to recover Relativistic
Causality in earlier "paradoxes" (such as the van Kampen thought-experiment),
while a more general consideration indicates that the temporal nonlocalities
found here demonstrate in part a causal propagation of phases of quantum
mechanical wavefunctions in the Schr\"odinger picture. This may open a direct
way to address time-dependent double-slit experiments and the associated causal
issuesComment: 49 pages, 1 figure, presented in Conferences "50 years of the
Aharonov-Bohm effect and 25 years of the Berry's phase" (Tel Aviv and
Bristol), published in Journ. Phys. A. Compared to the published paper, this
version has 17 additional lines after eqn.(14) for maximum clarity, and the
Abstract has been slightly modified and reduced from the published 2035
characters to the required 1920 character
High-Velocity Features of Calcium and Silicon in the Spectra of Type Ia Supernovae
"High-velocity features" (HVFs) are spectral features in Type Ia supernovae
(SNe Ia) that have minima indicating significantly higher (by greater than
about 6000 km/s) velocities than typical "photospheric-velocity features"
(PVFs). The PVFs are absorption features with minima indicating typical
photospheric (i.e., bulk ejecta) velocities (usually ~9000-15,000 km/s near
B-band maximum brightness). In this work we undertake the most in-depth study
of HVFs ever performed. The dataset used herein consists of 445 low-resolution
optical and near-infrared (NIR) spectra (at epochs up to 5 d past maximum
brightness) of 210 low-redshift SNe Ia that follow the "Phillips relation." A
series of Gaussian functions is fit to the data in order to characterise
possible HVFs of Ca II H&K, Si II {\lambda}6355, and the Ca II NIR triplet. The
temporal evolution of the velocities and strengths of the PVFs and HVFs of
these three spectral features is investigated, as are possible correlations
with other SN Ia observables. We find that while HVFs of Ca II are regularly
observed (except in underluminous SNe Ia, where they are never found), HVFs of
Si II {\lambda}6355 are significantly rarer, and they tend to exist at the
earliest epochs and mostly in objects with large photospheric velocities. It is
also shown that stronger HVFs of Si II {\lambda}6355 are found in objects that
lack C II absorption at early times and that have red ultraviolet/optical
colours near maximum brightness. These results lead to a self-consistent
connection between the presence and strength of HVFs of Si II {\lambda}6355 and
many other mutually correlated SN~Ia observables, including photospheric
velocity.Comment: 48 pages (22 of which are tables), 15 figures, 5 tables, re-submitted
to MNRAS (after first referee report
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