3,298 research outputs found
Deciphering the Pulsations of G 29-38 with Optical Time Series Spectroscopy
We present optical time series spectroscopy of the pulsating white dwarf star
G29-38 taken at the Very Large Telescope (VLT). By measuring the variations in
brightness, Doppler shift, and line shape of each spectrum, we explore the
physics of pulsation and measure the spherical degree () of each stellar
pulsation mode. We measure the physical motion of the g-modes correlated with
the brightness variations for three of the eight pulsation modes in this data
set. The varying line shape reveals the spherical degree of the pulsations, an
important quantity for properly modeling the interior of the star with
asteroseismology. Performing fits to the H, H, and H
lines, we quantify the changing shape of the line and compare them to models
and previous time series spectroscopy of G~29-38. These VLT data confirm
several identifications and add four new values, including an additional
=2 and a possible =4. In total from both sets of spectroscopy of
G29-38, eleven modes now have known spherical degrees.Comment: Accepted for publication by MNRA
Anaplasma marginale Actively Modulates Vacuolar Maturation During Intracellular Infection of Its Tick Vector, Dermacentor andersoni
ABSTRACT Tick-borne transmission of bacterial pathogens in the order Rickettsiales is responsible for diverse infectious diseases, many of them severe, in humans and animals. Transmission dynamics differ among these pathogens and are reflected in the pathogen-vector interaction. Anaplasma marginale has been shown to establish and maintain infectivity within Dermacentor spp. for weeks to months while escaping the complex network of vacuolar peptidases that are responsible for digestion ofthe tick blood meal. How this prolonged maintenance of infectivity in a potentially hostile environment is achieved has been unknown. Using the natural vector Dermacentor andersoni, we demonstrated that A. marginale-infected tick vacuoles (AmVs) concurrently recruit markers of the early endosome (Rab5), recycling endosome (Rab4 and Rab11), and late endosome (Rab7), are maintained near neutral pH, do not fuse with lysosomes, exclude the protease cathepsin L, and engage the endoplasmic reticulum and Golgi apparatus for up to 21 days post infection. Maintenance of this safe vacuolar niche requires active A. marginale protein synthesis; in its absence, the AmVs mature into acidic, protease-active phagolysosomes. Identification of this bacterially directed modeling of the tick midgut endosome provides a mechanistic basis for examination of the differences in transmission efficiency observed among A. marginale strains and among vector populations.
IMPORTANCE Ticks transmit a variety of intracellular bacterial pathogens that cause significant diseases in humans and animals. For successful transmission, these bacterial pathogens must first gain entry into the tick midgut digestive cells, avoid digestion, and establish a replicative niche without harming the tick vector. Little is known about how this replicative niche is established and maintained. Using the ruminant pathogen A. marginale and its natural tick vector, D. andersoni, this study characterized the features of the A. marginale niche in the tick midgut and demonstrates that A. marginale protein synthesis is required for the maintenance of this niche. This work opens a new line of inquiry about the pathogen effectors and their targets within the tick that mediate tick pathogen interactions and ultimately serve as the determinants of pathogen success
Incidental Findings on CT Scans in the Emergency Department
Objectives. Incidental findings on computed tomography (CT) scans are common. We sought to examine rates of findings and disclosure among discharged patients who received a CT scan in the ED.
Methods. Retrospective chart review (Aug-Oct 2009) of 600 patients age 18 and older discharged home from an urban Level 1 trauma center. CT reports were used to identify incidental findings and discharge paperwork was used to determine whether the patient was informed of these findings.
Results. There were 682 CT scans among 600 patients: 199 Abdomen & Pelvis, 405 Head, and 78 Thorax. A total of 348 incidental findings were documented in 228/682 (33.4%) of the scans, of which 34 (9.8%) were reported to patients in discharge paperwork. Patients with 1 incidental finding were less likely to receive disclosure than patients with 2 or more (P = .010). Patients age <60 were less likely to have incidental findings (P < .001). There was no significant disclosure or incidental finding difference by gender.
Conclusions. While previous research suggests that CT incidental findings are often benign, reporting to patients is recommended but this is rarely happening
Evaluation of MERRA-2-Based Ozone Profile Simulations with the Global Ozonesonde Network
Chemical transport model (CTM) hindcasts of ozone (O3) are useful for filling in observational gaps and providing context for observed O3 variability and trends. We use global networks of ozonesonde stations to evaluate the O3 profiles in two simulations running versions of the NASA Global Modeling Initiative (GMI) chemical mechanism. Both simulations are tied to the NASA Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) meteorological reanalysis: 1) The GMI CTM, and 2) The MERRA-2 GMI Replay (M2 GMI). Both simulations start in 1980, and are compared against >50,000 ozonesonde profiles from 37 global stations from the tropics to the poles. The comparisons allow us to evaluate how the Replay technique affects modeled O3 distribution, how an updated chemical mechanism in the GMI CTM affects simulated tropospheric O3 amounts, and how observed O3 distributions compare to the full set of model output. In general, M2 GMI O3 is ~10% higher than in the GMI CTM, and shows global near-surface and tropical upper troposphere/lower stratosphere (UT/LS) high biases. The updated chemical mechanism in the GMI CTM reduces these high biases. Both simulations show similar negative biases in tropical free-tropospheric O3, especially during typical biomass burning seasons. The simulations are highly-correlated with ozonesonde measurements, particularly in the UT/LS (r > 0.8), showing the ability of MERRA-2 to capture tropopause height variations. Both simulations show improved correlations with ozonesonde data and smaller O3 biases in recent years. We expect to use the sonde/model comparisons to diagnose causes of disagreement and to gauge the feasibility of calculating multidecadal O3 trends from the model output
Prevention Across the Spectrum: a randomized controlled trial of three programs to reduce risk factors for both eating disorders and obesity
Author version made available in accordance with publisher copyright policy.Background: A randomized-controlled trial (RCT) of 3 school-based programs and a no intervention control group was conducted to evaluate their efficacy in reducing eating disorder and obesity risk factors. Methods: N = 1,316 Grade 7 and 8 girls and boys (M age = 13.21 years) across three Australian states were randomly allocated to: Media Smart; Life Smart; Helping, Encouraging, Listening and Protecting Peers Initiative
(HELPP) or control (usual school class). Risk factors were measured at baseline, post-program (5-weeks later), and 6- and 12-month follow-up. Results: Media Smart girls had half the rate of onset of clinically significant concerns about shape and weight than control girls at 12-month follow-up. Media Smart and HELPP girls reported significantly lower weight and shape concern than Life Smart girls at 12-month follow-up. Media Smart and control girls scored significantly lower than HELPP girls on eating concerns and perceived pressure at 6-month follow-up. Media Smart and HELPP boys experienced significant benefit on media internalization compared to control boys and these were sustained at 12-month follow-up in Media Smart boys. A group x time effect found Media Smart participants reported more physical activity than control and HELPP participants at 6-month follow-up, while a main effect for group found Media Smart participants reported less screen time than controls. Conclusions: Media Smart was the only program to show benefit on both disordered eating and obesity risk factors. Whilst further investigations are indicated, this study suggests that this program is a promising approach to reducing risk factors for both problems
A Mentoring Guide for Female Faculty in Engineering
One widely accepted method for increasing the chances of success of female engineering and science students and faculty alike is to provide access to female role models and mentors. In this article we offer to new female faculty, and to those who would mentor them, an annotated list of text and electronic resources that address most of the most important challenges facing new female faculty in science and engineering
Estimating variance components and predicting breeding values for eventing disciplines and grades in sport horses
Eventing competitions in Great Britain (GB) comprise three disciplines, each split into four grades, yielding 12 discipline-grade traits. As there is a demand for tools to estimate (co)variance matrices with a large number of traits, the aim of this work was to investigate different methods to produce large (co)variance matrices using GB eventing data. Data from 1999 to 2008 were used and penalty points were converted to normal scores. A sire model was utilised to estimate fixed effects of gender, age and class, and random effects of sire, horse and rider. Three methods were used to estimate (co)variance matrices. Method 1 used a method based on Gibbs sampling and data augmentation and imputation. Methods 2a and 2b combined sub-matrices from bivariate analyses; one took samples from a multivariate Normal distribution defined by the covariance matrix from each bivariate analysis, then analysed these data in a 12-trait multivariate analysis; the other replaced negative eigenvalues in the matrix with positive values to obtain a positive definite (co)variance matrix. A formal comparison of models could not be conducted; however, estimates from all methods, particularly Methods 2a/2b, were in reasonable agreement. The computational requirements of Method 1 were much less compared with Methods 2a or 2b. Method 2a heritability estimates were as follows: for dressage 7.2% to 9.0%, for show jumping 8.9% to 16.2% and for cross-country 1.3% to 1.4%. Method 1 heritability estimates were higher for the advanced grades, particularly for dressage (17.1%) and show jumping (22.6%). Irrespective of the model, genetic correlations between grades, for dressage and show jumping, were positive, high and significant, ranging from 0.59 to 0.99 for Method 2a and 0.78 to 0.95 for Method 1. For cross-country, using Method 2a, genetic correlations were only significant between novice and pre-novice (0.75); however, using Method 1 estimates were all significant and low to moderate (0.36 to 0.70). Between-discipline correlations were all low and of mixed sign. All methods produced positive definite 12312 (co)variance matrices, suitable for the prediction of breeding values. Method 1 benefits from much reduced computational requirements, and by performing a true multivariate analysis
Finiteness and children with specific language impairment: an exploratory study
Children with specific language impairment (SLI) are well known for their difficulties in mastering the inflectional paradigms; in the case of learning German they also have problems with the appropriate verb position, in particular with the verb in second position. This paper explores the possibilities of applying a broader concept of finiteness to data from children with SLI in order to put their deficits, or rather their skills, into a wider perspective. The concept, as developed by Klein (1998, 2000), suggests that finiteness is tied to the assertion that a certain state of affairs is valid with regard to some topic time; that is, finiteness relates the propositional content to the topic component. Its realization involves the interaction of various grammatical devices and, possibly, lexical means like temporal adverbs. Furthermore, in the acquisition of finiteness it has been found that scope particles play a major role in both first- and second-language learning. The purpose of this paper is to analyze to what extent three German-learning children with SLI have mastered these grammatical and lexical means and to pinpoint the phase in the development of finiteness they have reached. The data to be examined are mostly narrative and taken from conversations and experiments. It will be shown that each child chooses a different developmental path to come to grips with the interaction of these devices
Measuring Transit Signal Recovery in the Kepler Pipeline II: Detection Efficiency as Calculated in One Year of Data
The Kepler planet sample can only be used to reconstruct the underlying
planet occurrence rate if the detection efficiency of the Kepler pipeline is
known, here we present the results of a second experiment aimed at
characterising this detection efficiency. We inject simulated transiting planet
signals into the pixel data of ~10,000 targets, spanning one year of
observations, and process the pixels as normal. We compare the set of
detections made by the pipeline with the expectation from the set of simulated
planets, and construct a sensitivity curve of signal recovery as a function of
the signal-to-noise of the simulated transit signal train. The sensitivity
curve does not meet the hypothetical maximum detection efficiency, however it
is not as pessimistic as some of the published estimates of the detection
efficiency. For the FGK stars in our sample, the sensitivity curve is well fit
by a gamma function with the coefficients a = 4.35 and b = 1.05. We also find
that the pipeline algorithms recover the depths and periods of the injected
signals with very high fidelity, especially for periods longer than 10 days. We
perform a simplified occurrence rate calculation using the measured detection
efficiency compared to previous assumptions of the detection efficiency found
in the literature to demonstrate the systematic error introduced into the
resulting occurrence rates. The discrepancies in the calculated occurrence
rates may go some way towards reconciling some of the inconsistencies found in
the literature.Comment: 13 pages, 7 figures, 1 electronic table, accepted by Ap
Drought-induced biomass burning as a source of black carbon to the central Himalaya since 1781 CE as reconstructed from the Dasuopu ice core
Himalayan glaciers are melting due to atmospheric warming, with the potential to limit access to water for more than 25 % of the global population that resides in these glacier meltwater catchments. Black carbon has been implicated as a factor that is contributing to Himalayan glacier melt, but its sources and mechanisms of delivery to the Himalayas remain controversial. Here, we provide a 211-year ice core record spanning 1781–1992 CE for refractory black carbon (rBC) deposition from the Dasuopu glacier ice core that has to date provided the highest-elevation ice core record (7200 m). We report an average rBC concentration of 1.5 µg L−1 (SD=5.0, n=1628) over the 211-year period. An increase in the frequency and magnitude of rBC deposition occurs after 1877 CE, accompanied by decreased snow accumulation associated with a shift in the North Atlantic Oscillation Index to a positive phase. Typically, rBC is deposited onto Dasuopu glacier during the non-monsoon season, and short-lived increases in rBC concentration are associated with periods of drought within neighboring regions in northwestern India, Afghanistan, and Pakistan. Using a combination of spectral and back-trajectory analyses, as well as a comparison with a concurrent analysis of trace metals at equivalent depths in the same ice core, we show that biomass burning resulting from dry conditions is a source of rBC to the central Himalaya and is responsible for deposition that is up to 60 times higher than the average rBC concentration over the time period analyzed. We suggest that biomass burning is a significant source of rBC to the central Himalaya and that the rBC record can be used to identify periods of drought in nearby regions that are upwind of Dasuopu glacier
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