1,620 research outputs found
The large-scale axisymmetric magnetic topology of avery-low-mass fully-convective star
Understanding how cool stars produce magnetic fields within their interiors
is crucial for predicting the impact of such fields, such as the activity cycle
of the Sun. In this respect, studying fully convective stars enables us to
investigate the role of convective zones in magnetic field generation. We
produced a magnetic map of a rapidly rotating, very-low-mass, fully convective
dwarf through tomographic imaging from time series of spectropolarimetric data.
Our results, which demonstrate that fully convective stars are able to trigger
axisymmetric large-scale poloidal fields without differential rotation,
challenge existing theoretical models of field generation in cool stars.Comment: 17 pages, 4 figures, supplementary online material (including 2
figures
A very faint core-collapse supernova in M85
An anomalous transient in the early Hubble-type (S0) galaxy Messier 85 (M85)
in the Virgo cluster was discovered by Kulkarni et al. (2007) on 7 January 2006
that had very low luminosity (peak absolute R-band magnitude MR of about -12)
that was constant over more than 80 days, red colour and narrow spectral lines,
which seem inconsistent with those observed in any known class of transient
events. Kulkarni et al. (2007) suggest an exotic stellar merger as the possible
origin. An alternative explanation is that the transient in M85 was a type
II-plateau supernova of extremely low luminosity, exploding in a lenticular
galaxy with residual star-forming activity. This intriguing transient might be
the faintest supernova that has ever been discovered.Comment: 7 pages, 2 figures. Submitted to Nature "Brief Communication Arising"
on 18 July 2007, Accepted on 17 August 2007. Arising from: Kulkarni et al.
2007, Nature, 447, 458-46
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Early Observations And Analysis Of The Type Ia SN 2014J In M82
We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (-10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I lambda 1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for OI, Mg II, Si II, S Ca a, and Fell suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from -10d to +29d, in the UBVRIJH and K-s bands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using R-v = 1.46, which is consistent with previous studies, SNooPy finds that A(v) = 1.80 for E(B - V)(host) = 1.23 +/- 0.06 mag. The maximum B-band brightness of -19.19 +/- 0.10 mag was reached on February 1.74 UT +/- 0.13 days and the supernova has a decline parameter, Delta m(15), of 1.12 +/- 0.02 mag.Department of Space, Government of IndiaHungarian OTKA NN-107637NSF AST-1109801, AST-1151462, AST-1211196NSF Astronomy and Astrophysics Postdoctoral Fellowship AST-1302771NASA through a grant from the Space Telescope Science Institute GO-12540NASA NAS5-26555Swedish Research CouncilSwedish National Space BoardDanish Agency for Science and Technology and Innovation realized through a Sapere Aude Level 2 grantAstronom
INFLAMMATORY BREAST NEOPLASMS: A SYSTEMATIC REVIEW
Overview: Inflammatory Breast Cancer (IBC) is a rare and very aggressive type of cancer that tends to develop at a younger age, compared with other subtypes of breast cancer. Because a distinct lump may not be noticeable, correct diagnosis takes longer and, therefore, successful treatment may hinder a patientâs prognostics. This study aims to conduct a systematic review of research articles on IBC. Methods: This is a systematic review of studies in the PubMed database to April 2013, which fit the eligibility criterion of âInflammatory Breast Neoplasmsâ (MeSH Terms), filtered by Languages (English OR Portuguese OR Spanish). Findings: Of the 119studies identified, 25 complied with the eligibility criterion for the disease, diagnostics, treatment and prognostics. Final Considerations :Despite methodological differences, findings evidence that although IBC presents particular features (lower survival rate and worse prognostics than most types of breast cancer), very few studies examine its epidemiology and specific risk factors in depth and use any other therapeutic approaches than those commonly used for other breast cancer subtypes. Therefore, further investigation of the diseaseâs aggressiveness is still necessary
Quantitative cross-species extrapolation between humans and fish: The case of the anti-depressant fluoxetine
This article has been made available through the Brunel Open Access Publishing Fund.Fish are an important model for the pharmacological and toxicological characterization of human pharmaceuticals in drug discovery, drug safety assessment and environmental toxicology. However, do fish respond to pharmaceuticals as humans do? To address this question, we provide a novel quantitative cross-species extrapolation approach (qCSE) based on the hypothesis that similar plasma concentrations of pharmaceuticals cause comparable target-mediated effects in both humans and fish at similar level of biological organization (Read-Across Hypothesis). To validate this hypothesis, the behavioural effects of the anti-depressant drug fluoxetine on the fish model fathead minnow (Pimephales promelas) were used as test case. Fish were exposed for 28 days to a range of measured water concentrations of fluoxetine (0.1, 1.0, 8.0, 16, 32, 64 ÎŒg/L) to produce plasma concentrations below, equal and above the range of Human Therapeutic Plasma Concentrations (HTPCs). Fluoxetine and its metabolite, norfluoxetine, were quantified in the plasma of individual fish and linked to behavioural anxiety-related endpoints. The minimum drug plasma concentrations that elicited anxiolytic responses in fish were above the upper value of the HTPC range, whereas no effects were observed at plasma concentrations below the HTPCs. In vivo metabolism of fluoxetine in humans and fish was similar, and displayed bi-phasic concentration-dependent kinetics driven by the auto-inhibitory dynamics and saturation of the enzymes that convert fluoxetine into norfluoxetine. The sensitivity of fish to fluoxetine was not so dissimilar from that of patients affected by general anxiety disorders. These results represent the first direct evidence of measured internal dose response effect of a pharmaceutical in fish, hence validating the Read-Across hypothesis applied to fluoxetine. Overall, this study demonstrates that the qCSE approach, anchored to internal drug concentrations, is a powerful tool to guide the assessment of the sensitivity of fish to pharmaceuticals, and strengthens the translational power of the cross-species extrapolation
Interpretation of the Veiling of the Photospheric Spectrum for T Tauri Stars in Terms of an Accretion Model
The problem on heating the atmospheres of T Tauri stars by radiation from an
accretion shock has been solved. The structure and radiation spectrum of the
emerging so-called hot spot have been calculated in the LTE approximation. The
emission not only in continuum but also in lines has been taken into account
for the first time when calculating the spot spectrum. Comparison with
observations has shown that the strongest of these lines manifest themselves as
narrow components of helium and metal emission lines, while the weaker ones
decrease significantly the depth of photospheric absorption lines, although
until now, this effect has been thought to be due to the emission continuum
alone. The veiling by lines changes the depth of different photospheric lines
to a very different degree even within a narrow spectral range. Therefore, the
nonmonotonic wavelength dependence of the degree of veiling r found for some
CTTS does not suggest a nontrivial spectral energy distribution of the veiling
continuum. In general, it makes sense to specify the degree of veiling r only
by providing the set of photospheric lines from which this quantity was
determined. We show that taking into account the contribution of lines to the
veiling of the photospheric spectrum can cause the existing estimates of the
accretion rate onto T Tauri stars to decrease by several times, with this being
also true for stars with a comparatively weakly veiled spectrum. Neglecting the
contribution of lines to the veiling can also lead to appreciable errors in
determining the effective temperature, interstellar extinction, radial
velocity, and vsin(i)
Cut Out Complications and Anisomelia of the Lower Limbs In Surgery With Valgus Reduction for Intertrochanteric Fractures
Background: The proximal fractures of the femur are counted among the group of orthopedic and traumatic pathologies which consume most of the financial resources set aside for health worldwide. Surgical treatment continues to be the treatment of choice for intertrochanteric fractures of the femur. However, although the surgical treatment of the proximal fracture of the femur is widely known and accepted in the orthopedic field, it is not without risk with the cut out being the most feared complication. Objective: This paper describes the complications of cut out or the anisomelia of the lower limbs of patients with intertrochanteric fractures who underwent valgus reduction surgery. Method: Sixty-one patients with 3rd and 4th degree, according to Tronzo classification, intertrochanteric fractures underwent surgery with the use of Dynamic hip screw type sliding screw and valgus reduction. The data were analyzed one year after surgery, when a functional assessment was made by scanometry, Tip-Apex Distance index diaphyseal cervical angle and the modified Merle d'AubignĂ© & Postel questionnaire. Kruskal-Wallis and Mann-Whitney tests were used for the statistical analysis, SpearmanĂąâŹâąs correlation test for the quantitative variables and the chi-squared test for the qualitative variables. Results: The correlation between the Tip-Apex Distance index and the diaphyseal cervical angle was statistically significant (rho=0.391, p=0.002), while the correlations between the Tip-Apex Distance index and the scanometry and the diaphyseal cervical angle and the scanometry were not significantly correlated. In accordance with the modified Merle dĂąâŹâąAubignĂ© & Postel questionnaire, 23 patients (37.7%) achieved a very good result, 29 patients (47.5%) had a good result, five patients (8.2%) obtained a moderately good result, one patient (1.6%) presented a reasonable result and three patients (4.9%) obtained a poor result. Conclusion: No cut out complications occurred in the 3rd and 4th degree intertrochanteric fractures with a Baumgaertner index Ăąâ°Â„ 25 mm, when the reduction and valgus fixation of the intertrochanteric fracture was performed with the Dynamic hip screw type sliding pin, as there was also, in the majority of patients, no anisomelia of the lower limbs
First principles electronic structure of spinel LiCr2O4: A possible half-metal?
We have employed first-principles electronic structure calculations to
examine the hypothetical (but plausible) oxide spinel, LiCr2O4 with the d^{2.5}
electronic configuration. The cell (cubic) and internal (oxygen position)
structural parameters have been obtained for this compound through structural
relaxation in the first-principles framework. Within the one-electron band
picture, we find that LiCr2O4 is magnetic, and a candidate half-metal. The
electronic structure is substantially different from the closely related and
well known rutile half-metal CrO2. In particular, we find a smaller conduction
band width in the spinel compound, perhaps as a result of the distinct topology
of the spinel crystal structure, and the reduced oxidation state. The magnetism
and half-metallicity of LiCr2O4 has been mapped in the parameter space of its
cubic crystal structure. Comparisons with superconducting LiTi2O4 (d^{0.5}),
heavy-fermion LiV2O4 (d^{1.5}) and charge-ordering LiMn2O4 (d^{3.5}) suggest
the effectiveness of a nearly-rigid band picture involving simple shifts of the
position of E_F in these very different materials. Comparisons are also made
with the electronic structure of ZnV2O4 (d^{2}), a correlated insulator that
undergoes a structural and antiferromagnetic phase transition.Comment: 9 pages, 7 Figures, version as published in PR
Effects of a multidisciplinary program on autonomic modulation in overweight or obese children and adolescents
Purpose: this study evaluated the effects of a multidisciplinary program on autonomic modulation in overweight or obese children and adolescents. Methods: fi fteen individuals with 10,93±2,28 years were submitted to autonomic evaluation using heart rate variability before and after a program based on physical exercises for three months, three times a week, 60 minutes per session and psychological and nutritional counseling. Data was analyzed using the paired t-test or Wilcoxon test and the level of signifi cance was set at P < 0.05. Results: multidisciplinary program was able to promote benefi ts in autonomic modulation observed thought temporal (SDNN: 39,96 ± 10,33 x 49,44 ± 12,31; p = 0,019; rMSSD: 28,97 ± 11,50 x 37,26 ± 11,17; p = 0,018), spectral (LFnu: 64,49 ± 12,21 x 56,74 ± 11,18; p = 0,014; HFnu: 35,50 ± 12,21 x 43,25 ± 11,18; p = 0,014) and geometrical (SD1: 20,51 ± 8,13 x 26,36 ± 7,90; p = 0,018 SD2: 52,31 ± 13,04 x 64,58 ± 16,33; p = 0,031) indices in overweigh and obese children and adolescents. Also, after the intervention there was a reduction on resting heart rate (88,53 ± 9,24 x 83,09 ± 7,93; p = 0,023) and there were changes in the classifi cation of overweigh 26,67% x 46,66% and obesity 73,33% x 53,33%, although not significant changes in body mass index. Conclusions: exercise program together with nutritional and psychological counseling is able to promote benefi ts in autonomic modulation in children and adolescents who are overweight or obese
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