135 research outputs found
Magnetic field in atypical prominence structures: Bubble, tornado and eruption
Spectropolarimetric observations of prominences have been obtained with the
THEMIS telescope during four years of coordinated campaigns. Our aim is now to
understand the conditions of the cool plasma and magnetism in `atypical'
prominences, namely when the measured inclination of the magnetic field
departs, to some extent, from the predominantly horizontal field found in
`typical' prominences. What is the role of the magnetic field in these
prominence types? Are plasma dynamics more important in these cases than the
magnetic support? We focus our study on three types of `atypical' prominences
(tornadoes, bubbles and jet-like prominence eruptions) that have all been
observed by THEMIS in the He I D_3 line, from which the Stokes parameters can
be derived. The magnetic field strength, inclination and azimuth in each pixel
are obtained by using the Principal Component Analysis inversion method on a
model of single scattering in the presence of the Hanle effect. The magnetic
field in tornadoes is found to be more or less horizontal, whereas for the
eruptive prominence it is mostly vertical. We estimate a tendency towards
higher values of magnetic field strength inside the bubbles than outside in the
surrounding prominence. In all of the models in our database, only one magnetic
field orientation is considered for each pixel. While sufficient for most of
the main prominence body, this assumption appears to be oversimplified in
atypical prominence structures. We should consider these observations as the
result of superposition of multiple magnetic fields, possibly even with a
turbulent field component.Comment: 13 pages, 9 figure
A role of biomarkers in systemic lupus erythematous: a comprehensive review
Systemic lupus erythematous (SLE) is an auto immune disease that can involve almost all body organs. Lupus erythematous may be classified in to several subtypes according to clinical features including systemic and cutaneous lupus erythematous, drug induced lupus and neonatal lupus. SLE progression includes in the immune system. Pathological manifestation of SLE are due to antibody formation and deposition of immune complexes in different organs of the body. Due to formation or disposition of immune complex in different body tissues and vessels, which may lead to complement activation and more organ damage. Other factors include genetic factors, hormonal abnormalities and environmental factors. There is a challenge in establishing a diagnosis, determining disease activity. Therefore, an important needs is a repertoire of biomarkers that can accurately with prediction, diagnosis, and disease, activity monitoring and stratifying patient. SLE can be diagnosed by using different biomarkers as anti-smith antibodies (ANAS), antibodies to double stand deoxyribonucleic acid (DNA) and level of complement components C3 C4, and CH50. More immunological biomarkers are needed to be better understanding of disease SLE. SLE is an autoimmune disease which can travel to any organ or a system i.e. biomarkers for cardiovascular involvement in SLE, biomarkers for respiratory involvement in SLE, biomarkers for lupus arthritis
Helioseismology with PICARD
PICARD is a CNES micro-satellite launched in June 2010 (Thuillier at al.
2006). Its main goal is to measure the solar shape, total and spectral
irradiance during the ascending phase of the activity cycle. The SODISM
telescope onboard PICARD also allows us to conduct a program for
helioseismology in intensity at 535.7 nm (Corbard et al. 2008). One-minute
cadence low-resolution full images are available for a so-called medium-
program, and high-resolution images of the limb recorded every 2 minutes are
used to study mode amplification near the limb in the perspective of g-mode
search. First analyses and results from these two programs are presented here.Comment: 6 pages, 6 figures, Eclipse on the Coral Sea: Cycle 24 Ascending,
GONG 2012 / LWS/SDO-5 / SOHO 27, November 12 - 16, 2012, Palm Cove,
Queensland. Accepted for publication in Journal of Physics Conference Series
on March 1st 201
Three-dimensional interferometric, spectrometric, and planetary views of Procyon
We used a new realistic 3D radiative-hydrodynamical model atmosphere of
Procyon generated with the Stagger Code and synthetic spectra computed with the
radiative transfer code Optim3D to re-analyze interferometric and spectroscopic
data from the optical to the infrared of Procyon. We compute intensity maps in
two optical filters centered at 500 and 800 nm (MARK III) and one infrared
filter centered at 2200 nm (VINCI). We constructed stellar disk images
accounting for the center-to-limb variations and used them to derive visibility
amplitudes and closure phases. We provide 3D limb-darkening coefficients in the
optical as well as in the infrared. We show that visibility curves and closure
phases show clear deviations from circular symmetry from the 3rd lobe on. These
deviations are detectable with current interferometers using closure phases. We
derive new angular diameters at different wavelengths with two independent
methods based on 3D simulations. We find a diameter_Vinci = 5.390 \pm 0.03 mas
that this is confirmed by an independent asteroseismic estimation. The
resulting Teff is 6591 K, which is consistent with the infrared flux method
determinations. We find also a value of the surface gravity log g = 4.01 \pm
0.03 that is larger by 0.05 dex from literature values. Spectrophotometric
comparisons with observations provide very good agreement with the spectral
energy distribution and photometric colors, allowing us to conclude that the
thermal gradient of the simulation matches fairly well Procyon. Finally, we
show that the granulation pattern of a planet hosting Procyon-like star has a
non-negligible impact on the detection of hot Jupiters in the infrared using
interferometry closure phases. It is then crucial to have a comprehensive
knowledge of the host star to directly detect and characterize hot Jupiters. In
this respect, RHD simulations are very important to reach this aim.Comment: Accepted for publication on Astronomy and Astrophysics, 14 pages, 12
figure
Asteroseismology of Procyon with SOPHIE
This paper reports a 9-night asteroseismic observation program conducted in
January 2007 with the new spectrometer Sophie at the OHP 193-cm telescope, on
the F5 IV-V target Procyon A. This first asteroseismic program with Sophie was
intended to test the performance of the instrument with a bright but demanding
asteroseismic target and was part of a multisite network. The Sophie spectra
have been reduced with the data reduction software provided by OHP. The Procyon
asteroseismic data were then analyzed with statistical tools. The asymptotic
analysis has been conducted considering possible curvature in the echelle
diagram analysis. These observations have proven the efficient performance of
Sophie used as an asteroseismometer, and succeed in a clear detection of the
large spacing. An \'echelle diagram based on the 54-Hz spacing shows clear
ridges. Identification of the peaks exhibits large spacings varying from about
52 Hz to 56 Hz.Comment: 7 pages, 7 figure
Optimizing structural modeling for a specific protein scaffold: knottins or inhibitor cystine knots
<p>Abstract</p> <p>Background</p> <p>Knottins are small, diverse and stable proteins with important drug design potential. They can be classified in 30 families which cover a wide range of sequences (1621 sequenced), three-dimensional structures (155 solved) and functions (> 10). Inter knottin similarity lies mainly between 15% and 40% sequence identity and 1.5 to 4.5 Å backbone deviations although they all share a tightly knotted disulfide core. This important variability is likely to arise from the highly diverse loops which connect the successive knotted cysteines. The prediction of structural models for all knottin sequences would open new directions for the analysis of interaction sites and to provide a better understanding of the structural and functional organization of proteins sharing this scaffold.</p> <p>Results</p> <p>We have designed an automated modeling procedure for predicting the three-dimensionnal structure of knottins. The different steps of the homology modeling pipeline were carefully optimized relatively to a test set of knottins with known structures: template selection and alignment, extraction of structural constraints and model building, model evaluation and refinement. After optimization, the accuracy of predicted models was shown to lie between 1.50 and 1.96 Å from native structures at 50% and 10% maximum sequence identity levels, respectively. These average model deviations represent an improvement varying between 0.74 and 1.17 Å over a basic homology modeling derived from a unique template. A database of 1621 structural models for all known knottin sequences was generated and is freely accessible from our web server at <url>http://knottin.cbs.cnrs.fr</url>. Models can also be interactively constructed from any knottin sequence using the structure prediction module Knoter1D3D available from our protein analysis toolkit PAT at <url>http://pat.cbs.cnrs.fr</url>.</p> <p>Conclusions</p> <p>This work explores different directions for a systematic homology modeling of a diverse family of protein sequences. In particular, we have shown that the accuracy of the models constructed at a low level of sequence identity can be improved by 1) a careful optimization of the modeling procedure, 2) the combination of multiple structural templates and 3) the use of conserved structural features as modeling restraints.</p
Replication for Web Hosting Systems
Replication is a well-known technique to improve the accessibility of Web sites. It generally offers reduced client latencies and increases a site’s availability. However, applying replication techniques is not trivial, and various Content Delivery Networks (CDNs) have been created to facilitate replication for digital content providers. Th
The magnetism of the solar interior for a complete MHD solar vision
The solar magnetism is no more considered as a purely superficial phenomenon.
The SoHO community has shown that the length of the solar cycle depends on the
transition region between radiation and convection. Nevertheless, the internal
solar (stellar) magnetism stays poorly known. Starting in 2008, the American
instrument HMI/SDO and the European microsatellite PICARD will enrich our view
of the Sun-Earth relationship. Thus obtaining a complete MHD solar picture is a
clear objective for the next decades and it requires complementary observations
of the dynamics of the radiative zone. For that ambitious goal, space
prototypes are being developed to improve gravity mode detection. The Sun is
unique to progress on the topology of deep internal magnetic fields and to
understand the complex mechanisms which provoke photospheric and coronal
magnetic changes and possible longer cycles important for human life. We
propose the following roadmap in Europe to contribute to this "impressive"
revolution in Astronomy and in our Sun-Earth relationship: SoHO (1995-2007),
PICARD (2008-2010), DynaMICS (2009-2017) in parallel to SDO (2008-2017) then a
world-class mission located at the L1 orbit or above the solar poles.Comment: 10 pages, 8 figures, will appear in the proceedings of 2005 ESLAB
symposium 19-21 April 200
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