4,533 research outputs found
Early optical spectra of nova V1369 Cen show presence of Lithium
We present early high resolution spectroscopic observations of the nova V1369
Cen. We have detected an absorption feature at 6695.6 \AA\, that we have
identified as blue--shifted Li I 6708 \AA. The absorption line,
moving at -550 km/s, was observed in five high-resolution spectra of the nova
obtained at different epochs. On the basis of the intensity of this absorption
line we infer that a single nova outburst can inject in the Galaxy
0.3 - 4.8 M. Given the current estimates of
Galactic nova rate, this amount is sufficient to explain the puzzling origin of
the overabundance of Lithium observed in young star populations.Comment: 6 pages, 5 figures, accepted for publication in ApJLetter
Assessing Physician Response Rate Using a Mixed-Mode Survey
Background. It is important to minimize time and cost of physician surveys while still achieving a reasonable response rate. Mixed-mode survey administration appears to improve response rates and decrease bias. A literature review revealed physician response rates to mixed-mode surveys averaged about 68%. However, no identified studies used the combination of e-mail, fax, and telephone. The purpose of this study was to evaluate physician response rates based on surveys first administered by e-mail, then fax, then telephone. Methods. Surveys initially were administered by e-mail to 149 physicians utilizing SurveyMonkey©. Two follow-up reminder e-mails were sent to non-respondents at two-week intervals. Surveys then were faxed to physicians who had not responded. A follow-up fax was sent to non-respondents one week later. Finally, phone interviews were attempted with physicians who had not responded by e-mail or fax; each physician was called at least twice. Results. Of the 149 eligible physicians, 102 completed the survey for a response rate of 68.5%. Of those who responded, 49 (48%) responded by e-mail, 25 (24.5%) by fax, and 28 (27.5%) by phone. Mode of response did not differ by gender, specialization, or years in practice. In addition, mode of response was not related to the primary study question, physician willingness to use text messaging for immunization reminders. Conclusions. This mix of survey methodologies appeared to be a feasible combination for achieving physician responses and may be more cost effective than other mixed methods
Comparison of work fluctuation relations
We compare two predictions regarding the microscopic fluctuations of a system
that is driven away from equilibrium: one due to Crooks [J. Stat. Phys. 90,
1481 (1998)] which has gained recent attention in the context of nonequilibrium
work and fluctuation theorems, and an earlier, analogous result obtained by
Bochkov and Kuzovlev [Zh. Eksp. Teor. Fiz. 72(1), 238247 (1977)]. Both results
quantify irreversible behavior by comparing probabilities of observing
particular microscopic trajectories during thermodynamic processes related by
time-reversal, and both are expressed in terms of the work performed when
driving the system away from equilibrium. By deriving these two predictions
within a single, Hamiltonian framework, we clarify the precise relationship
between them, and discuss how the different definitions of work used by the two
sets of authors gives rise to different physical interpretations. We then
obtain a extended fluctuation relation that contains both the Crooks and the
Bochkov-Kuzovlev results as special cases.Comment: 14 pages with 1 figure, accepted for publication in the Journal of
Statistical Mechanic
Hinode/Extreme-Ultraviolet Imaging Spectrometer Observations of the Temperature Structure of the Quiet Corona
We present a Differential Emission Measure (DEM) analysis of the quiet solar
corona on disk using data obtained by the Extreme-ultraviolet Imaging
Spectrometer (EIS) on {\it Hinode}. We show that the expected quiet Sun DEM
distribution can be recovered from judiciously selected lines, and that their
average intensities can be reproduced to within 30%. We present a subset of
these selected lines spanning the temperature range T = 5.6 to 6.4 K
that can be used to derive the DEM distribution reliably. The subset can be
used without the need for extensive measurements and the observed intensities
can be reproduced to within the estimated uncertainty in the pre-launch
calibration of EIS. Furthermore, using this subset, we also demonstrate that
the quiet coronal DEM distribution can be recovered on size scales down to the
spatial resolution of the instrument (1 pixels). The subset will therefore
be useful for studies of small-scale spatial inhomogeneities in the coronal
temperature structure, for example, in addition to studies requiring multiple
DEM derivations in space or time. We apply the subset to 45 quiet Sun datasets
taken in the period 2007 January to April, and show that although the absolute
magnitude of the coronal DEM may scale with the amount of released energy, the
shape of the distribution is very similar up to at least T 6.2 K
in all cases. This result is consistent with the view that the {\it shape} of
the quiet Sun DEM is mainly a function of the radiating and conducting
properties of the plasma and is fairly insensitive to the location and rate of
energy deposition. This {\it universal} DEM may be sensitive to other factors
such as loop geometry, flows, and the heating mechanism, but if so they cannot
vary significantly from quiet Sun region to region.Comment: Version accepted by ApJ and published in ApJ 705. Abridged abstrac
Effective bioreduction of hexavalent chromium–contaminated water in fixed-film bioreactors
Hexavalent chromium (Cr6+) contamination from a dolomite stone mine in Limpopo Province, South Africa, has resulted in extensive groundwater contamination. In order to circumvent any further negative environmental impact at this site, an effective and sustainable treatment strategy for the removal of up to 6.49 mg/. Cr6+ from the groundwater was developed. Laboratory-scale, continuous up-flow bioreactors were constructed to evaluate reduction of Cr6+, with a residence time of 24 h, an efficiency porosity of 44% and a flow rate of 1.5 m./min. Stoichiometrically balancing terminal electron acceptors in the feed water with a selected electron donor, directed reactor balance for complete Cr6+ reduction. The microbial community shifted in relative dominance during operation to establish an optimal metal-reducing community, including Enterobacter cloacae, Flavobacterium sp. and Ralstonia sp., which achieved 100% reduction. Evaluation after reactor termination with SEM-EDX and XRD confirmed the establishment of biofilm on the reactor matrix, as well as trivalent chromium (Cr3+) precipitation within the reactor. Due to gravitational force, high concentrations of Cr3+ were found in the bottom third of the reactor. Based on the results from the laboratory investigation, a 24 000 . fixed-film pilot bioreactor was designed and constructed at this site. Influent flow rates, electron donor injection and automated sampling were remotely controlled by a programmable logic controller (PLC). Similar to the laboratory column study, steady state conditions could be achieved and successful Cr6+ reduction was evident. This is the first up-scaled, effective demonstration of a biological chromium(VI) bioremediation system in South Africa.Keywords: Bioreduction, fixed-film reactor, hexavalent chromium, microbial diversit
Addressing the clumsiness loophole in a Leggett-Garg test of macrorealism
The rise of quantum information theory has lent new relevance to experimental
tests for non-classicality, particularly in controversial cases such as
adiabatic quantum computing superconducting circuits. The Leggett-Garg
inequality is a "Bell inequality in time" designed to indicate whether a single
quantum system behaves in a macrorealistic fashion. Unfortunately, a violation
of the inequality can only show that the system is either (i)
non-macrorealistic or (ii) macrorealistic but subjected to a measurement
technique that happens to disturb the system. The "clumsiness" loophole (ii)
provides reliable refuge for the stubborn macrorealist, who can invoke it to
brand recent experimental and theoretical work on the Leggett-Garg test
inconclusive. Here, we present a revised Leggett-Garg protocol that permits one
to conclude that a system is either (i) non-macrorealistic or (ii)
macrorealistic but with the property that two seemingly non-invasive
measurements can somehow collude and strongly disturb the system. By providing
an explicit check of the invasiveness of the measurements, the protocol
replaces the clumsiness loophole with a significantly smaller "collusion"
loophole.Comment: 7 pages, 3 figure
CCL3 and MMP-9 are induced by TL1A during death receptor 3 (TNFRSF25)-dependent osteoclast function and systemic bone loss
FLC was funded by an Arthritis Research UK PhD studentship (Grant code: 18598) awarded to ASW, ECYW and MDS. JOW was funded by a British Heart Foundation PhD studentship (Reference: FS/11/26/ 28750). ACB's PhD studentship was jointly funded by the School of Medicine and Rheumatology Research Fund (Cardiff University) and LJ's PhD studentship was jointly funded by the School of Medicine and the President's Scholarship Fund (Cardiff University) awarded to ASW. ECYW was additionally funded by MRC Project Grant G0901119.Peer reviewedPublisher PD
Comparison of the Standardized Video Interview and Interview Assessments of Professionalism and Interpersonal Communication Skills in Emergency Medicine
ObjectivesThe Association of American Medical Colleges Standardized Video Interview (SVI) was recently added as a component of emergency medicine (EM) residency applications to provide additional information about interpersonal communication skills (ICS) and knowledge of professionalism (PROF) behaviors. Our objective was to ascertain the correlation between the SVI and residency interviewer assessments of PROF and ICS. Secondary objectives included examination of 1) inter‐ and intrainstitutional assessments of ICS and PROF, 2) correlation of SVI scores with rank order list (ROL) positions, and 3) the potential influence of gender on interview day assessments.MethodsWe conducted an observational study using prospectively collected data from seven EM residency programs during 2017 and 2018 using a standardized instrument. Correlations between interview day PROF/ICS scores and the SVI were tested. A one‐way analysis of variance was used to analyze the association of SVI and ROL position. Gender differences were assessed with independent‐groups t‐tests.ResultsA total of 1,264 interview‐day encounters from 773 unique applicants resulted in 4,854 interviews conducted by 151 interviewers. Both PROF and ICS demonstrated a small positive correlation with the SVI score (r = 0.16 and r = 0.17, respectively). ROL position was associated with SVI score (p < 0.001), with mean SVI scores for top‐, middle‐, and bottom‐third applicants being 20.9, 20.5, and 19.8, respectively. No group differences with gender were identified on assessments of PROF or ICS.ConclusionsInterview assessments of PROF and ICS have a small, positive correlation with SVI scores. These residency selection tools may be measuring related, but not redundant, applicant characteristics. We did not identify gender differences in interview assessments.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150548/1/aet210346_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150548/2/aet210346.pd
Fast approximation of centrality and distances in hyperbolic graphs
We show that the eccentricities (and thus the centrality indices) of all
vertices of a -hyperbolic graph can be computed in linear
time with an additive one-sided error of at most , i.e., after a
linear time preprocessing, for every vertex of one can compute in
time an estimate of its eccentricity such that
for a small constant . We
prove that every -hyperbolic graph has a shortest path tree,
constructible in linear time, such that for every vertex of ,
. These results are based on an
interesting monotonicity property of the eccentricity function of hyperbolic
graphs: the closer a vertex is to the center of , the smaller its
eccentricity is. We also show that the distance matrix of with an additive
one-sided error of at most can be computed in
time, where is a small constant. Recent empirical studies show that
many real-world graphs (including Internet application networks, web networks,
collaboration networks, social networks, biological networks, and others) have
small hyperbolicity. So, we analyze the performance of our algorithms for
approximating centrality and distance matrix on a number of real-world
networks. Our experimental results show that the obtained estimates are even
better than the theoretical bounds.Comment: arXiv admin note: text overlap with arXiv:1506.01799 by other author
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