1,249 research outputs found
EUVE J0425.6-5714: A Newly Discovered AM Herculis Star
We detected a new AM Her star serendipitously in a 25 day observation with
the EUVE satellite. A coherent period of 85.82 min is present in the EUVE Deep
Survey imager light curve of this source. A spectroscopic identification is
made with a 19th magnitude blue star that has H and He emission lines, and
broad cyclotron humps typical of a magnetic cataclysmic variable. A lower limit
to the polar magnetic field of 46 MG is estimated from the spacing of the
cyclotron harmonics. EUVE J0425.6-5714 is also detected in archival ROSAT HRI
observations spanning two months, and its stable and highly structured light
curve permits us to fit a coherent ephemeris linking the ROSAT and EUVE data
over a 1.3 yr gap. The derived period is 85.82107 +/- 0.00020 min, and the
ephemeris should be accurate to 0.1 cycles until the year 2005. A narrow but
partial X-ray eclipse suggests that this object belongs to the group of Am Her
stars whose viewing geometry is such that the accretion stream periodically
occults the soft X-ray emitting accretion spot on the surface of the white
dwarf. A non-detection of hard X-rays from ASCA observations that are
contemporaneous with the ROSAT HRI shows that the soft X-rays must dominate by
at least an order of magnitude, which is consistent with a known trend among AM
Her stars with large magnetic field. This object should not be confused with
the Seyfert galaxy 1H 0419-577 (= LB 1727), another X-ray/EUV source which lies
only 4' away, and was the principal target of these monitoring observations.Comment: 13 pages, 5 figures, to appear in PASP, Dec. 1998 issu
Validity of an enhanced EQ-5D-5L measure with an added cognitive dimension in patients with stroke
Objective: The 5-level EuroQoL (EQ-5D-5L) is a patient-reported outcome measure frequently used in stroke research. However, it does not assess the cognitive problems many patients with stroke experience. The aim of this article is to compare the content validity, internal consistency and discriminative ability of the EQ-5D-5L with and without an additional cognitive domain (EQ-5D-5L+C), administered three months post-stroke. Design: Cross-sectional study. Setting: Six general hospitals in the Netherlands. Subjects: In all, 360 individuals with stroke three months after the event. Interventions: Not applicable. Main measures: The modified Rankin Scale and EQ-5D-5L+C were administered in telephone interviews three months post-stroke. Results: A total of 360 patients with stroke were included. Mean age was 68.8 years (standard deviation (SD) = 11.7), 143 (40%) were female, 334 (93%) had had an ischemic stroke, 165 (46%) had a National Institutes of Health Stroke Scale (NIHSS) score ⩜ 4 at presentation and the Barthel Index was 17.2 (SD = 4) four days post-stroke. Cognitive problems were reported by 199 (55%) patients three months post-stroke. Internal consistencies of the EQ-5D-5L and EQ-5D-5L+C were 0.75 and 0.77, respectively. Adding a cognitive domain resulted in a decrease of the ceiling effect from 22% to 14%. Both EQ-5D-5L and EQ-5D-5L+C showed good discriminative ability, but differences between patients with different modified Rankin Scale scores and with/without reported decrease in health and daily activities were slightly larger with the EQ-5D-5L+C compared to the EQ-5D-5L. Conclusions: The EQ-5D-5L+C, which includes a cognitive domain that is highly significant for stroke patients, showed increased content validity and good discriminative ability, without losing internal consistency
Reduced masticatory function is related to lower satellite cell numbers in masseter muscle
The physiology of masseter muscles is known to change in response to functional demands, but the effect on the satellite cell (SC) population is not known. In this study, the hypothesis is tested that a decreased functional demand of the masseter muscle causes a reduction of SCs. To this end, twelve 5-week-old male Sprague-Dawley rats were put on a soft diet (SD, n = 6) or a hard diet (HD, n = 6) and sacrificed after 14 days. Paraffin sections of the superficial masseter and the m. digastricus (control muscle) were stained with haematoxylin and eosin for tissue survey and with anti-myosin heavy chain (MHC) for slow and fast fibres. Frozen sections of both muscles were double-stained for collagen type IV and Pax7. Slow MHC fibres were equally distributed in the m. digastricus but only localized in a small area of the m. masseter. No differences between HD or SD for the m. digastricus were found. The m. masseter had more SCs per fibre in HD than in SD (0.093 ± 0.007 and 0.081 ± 0.008, respectively; P = 0.027). The m. masseter had more fibres per surface area than the m. digastricus in rats with an SD group (758.1 ± 101.6 and 568.4±85.6, P = 0.047) and a HD group (737.7 ± 32.6 and 592.2 ± 82.2; P = 0.007). The m. digastricus had more SCs per fibre than the m. masseter in the SD group (0.094 ± 0.01 and 0.081 ± 0.008; P = 0.039). These results suggest that reduced masseter muscle function is related to a lower number of SCs. Reduced muscle function might decrease microdamage and hence the requirement of SCs in the muscle fibre
Cyclotron modeling phase-resolved infrared spectroscopy of polars I: EF Eridani
We present phase-resolved low resolution infrared spectra of the polar EF
Eridani obtained over a period of 2 years with SPEX on the IRTF. The spectra,
covering the wavelength range 0.8 to 2.4 microns, are dominated by cyclotron
emission at all phases. We use a ``Constant Lambda'' prescription to attempt to
model the changing cyclotron features seen in the spectra. A single cyclotron
emission component with B = 12.6 MG, and a plasma temperature of kT = 5.0 keV,
does a reasonable job in matching the features seen in the H and K bands, but
fails to completely reproduce the morphology shortward of 1.6 microns. We find
that a two component model, where both components have similar properties, but
whose contributions differ with viewing geometry, provides an excellent fit to
the data. We discuss the implications of our models and compare them with
previously published results. In addition, we show that a cyclotron model with
similar properties to those used for modeling the infrared spectra, but with a
field strength of B = 115 MG, can explain the GALEX observations of EF Eri.Comment: 25 pages, 5 figures, to appear in Ap
Diagnosis of Kawasaki disease using a minimal whole blood gene expression signature
Importance There is no diagnostic test for Kawasaki disease (KD). Diagnosis is based on clinical features shared with other febrile conditions, frequently resulting in delayed or missed treatment and an increased risk of coronary artery aneurysms. Objective To identify a whole blood gene expression signature that distinguishes children with KD in the first week of illness from other febrile conditions. Design Case-control discovery study groups comprising training, test, and validation groups of children with KD or comparator febrile illness. Setting Hospitals in the UK, Spain, Netherlands and USA. Participants The training and test discovery group comprised 404 children with infectious and inflammatory conditions (78 KD, 84 other inflammatory diseases, 242 bacterial or viral infections) and 55 healthy controls. The independent validation group included 130 febrile children and 102 KD patients, including 72 in the first 7 days of illness. Exposures Whole blood gene expression was evaluated using microarrays, and minimal transcript sets distinguishing KD were identified using a novel variable selection method (Parallel Deterministic Model Search). Main outcomes and measures The ability of transcript signatures - implemented as Disease Risk Scores - to discriminate KD cases from controls, was assessed by Area Under the Curve (AUC), sensitivity, and specificity at the optimal cut-point according to Youdenâs index. Results A 13-transcript signature identified in the discovery training set distinguished KD from other infectious and inflammatory conditions in the discovery test set with AUC, sensitivity, and specificity (95% confidence intervals (CI)) of 96.2% (92.5-99.9), 81.7% (60.0-94.8), and 92.1% (84.0-97.0), respectively. In the validation set, the signature distinguished KD from febrile controls with AUC, sensitivity, and specificity (95% CI) of 94.6% (91.3-98.0), 85.9% (76.8-92.6), and 89.1% (83.0-93.7) respectively. The signature was applied to clinically defined categories of Definite, Highly Probable and Possible KD resulting in AUCs of 98.1%, 96.3% and 70.0% respectively, mirroring clinical certainty. Conclusions and relevance A 13-transcript blood gene expression signature distinguished KD from other febrile conditions. Diagnostic accuracy increased with certainty of clinical diagnosis. A test incorporating the 13-transcript Disease Risk Score may enable earlier diagnosis and treatment of KD, and reduce inappropriate treatment in those with other diagnoses
The Three Dimensional Structure of EUV Accretion Regions in AM Herculis Stars: Modeling of EUV Photometric and Spectroscopic Observations
We have developed a model of the high-energy accretion region for magnetic
cataclysmic variables and applied it to {\it Extreme Ultraviolet Explorer}
observations of 10 AM Herculis type systems. The major features of the EUV
light curves are well described by the model. The light curves exhibit a large
variety of features such as eclipses of the accretion region by the secondary
star and the accretion stream, and dips caused by material very close to the
accretion region. While all the observed features of the light curves are
highly dependent on viewing geometry, none of the light curves are consistent
with a flat, circular accretion spot whose lightcurve would vary solely from
projection effects. The accretion region immediately above the WD surface is a
source of EUV radiation caused by either a vertical extent to the accretion
spot, or Compton scattering off electrons in the accretion column, or, very
likely, both. Our model yields spot sizes averaging 0.06 R, or the WD surface area, and average spot heights of 0.023
R. Spectra extracted during broad dip phases are softer than spectra
during the out-of-dip phases. This spectral ratio measurement leads to the
conclusion that Compton scattering, some absorption by a warm absorber,
geometric effects, an asymmetric temperature structure in the accretion region
and an asymmetric density structure of the accretion columnare all important
components needed to fully explain the data. Spectra extracted at phases where
the accretion spot is hidden behind the limb of the WD, but with the accretion
column immediately above the spot still visible, show no evidence of emission
features characteristic of a hot plasma.Comment: 30 Pages, 11 Figure
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