17 research outputs found
Electron acceleration sites in a large-scale coronal structure
Radio observations and interplanetary particle measurements have
shown that even in the absence of conspicuous violent processes in the low
atmosphere (such as Hα ïŹares) electrons are accelerated in the corona, most
likely at higher altitudes than during ïŹares (â„0.5 R above the
photosphere). The paper presents direct evidence on the acceleration sites from
a case study of radio, visible light and soft X-ray observations: electrons are
repeatedly accelerated in a large-scale coronal structure which is identiïŹed
with a streamer in coronographic observations. Energy is simultaneously
released in an active region near the base of the structure and at a height of
âŒ1 R , over several hours before the large-scale structure erupts. Energy
input is observed in at least two emerging active regions underneath the
streamer. The coronal conïŹguration is three-dimensional, overlying a whole
quadrant of the Sun. It is argued that the observations trace multiple sites of
energy release presumably in current sheets embedded within the streamer, in
agreement with scenarios developed for the acceleration of electrons seen in
the corona and at 1 AU, and for the evolution of large-scale coronal structures
towards eruption
Analysis and interpretation of a fast limb CME with eruptive prominence, C-flare and EUV dimming
Coronal Mass ejections or CMEs are large dynamical solar-corona events. The
mass balance and kinematics of a fast limb CME, including its prominence
progenitor and the associated flare, will be compared with computed magnetic
structures to look for their origin and effect.
Multi-wavelength ground-based and space-borne observations are used to study
a fast W-limb CME event of December 2, 2003, taking into account both on and
off disk observations. Its erupting prominence is measured at high cadence with
the Pic du Midi full H-alpha line-flux imaging coronagraph. EUV images from
space instruments are processed including difference imaging. SOHO/LASCO images
are used to study the mass excess and motions. A fast bright expanding coronal
loop is identified in the region recorded slightly later by GOES as a C7.2
flare, followed by a brightening and an acceleration phase of the erupting
material with both cool and hot components. The total coronal radiative flux
dropped by 5 percent in the EUV channels, revealing a large dimming effect at
and above the limb. The typical 3-part structure observed 1 hour later shows a
core shaped similarly to the eruptive filament/prominence. The total measured
mass of the escaping CME (1.5x10to16 g from C2 LASCO observations) definitely
exceeds the estimated mass of the escaping cool prominence material although
assumptions made to analyse the Ha erupting prominence, as well as the
corresponding EUV darkening of the filament observed several days before, made
this evaluation uncertain by a factor of 2. From the current free extrapolation
we discuss the shape of the magnetic neutral surface and a possible scenario
leading to an instability, including the small scale dynamics inside and around
the filament.Comment: 11 pages, 9 figure
Risk of Myocardial Infarction in Parents of HIV-infected Individuals: a population-based Cohort Study
<p>Abstract</p> <p>Background</p> <p>Previous studies have indicated an increased risk of myocardial infarction (MI) in HIV infected individuals especially after start of highly active antiretroviral therapy (HAART). It is however controversial whether the increased risk of atherosclerotic disease is exclusively associated with the HIV disease and HAART or whether life-style related or genetic factors also increase the risk in this population. To establish whether the increased risk of myocardial infarction in HIV patients partly reflects an increased risk of MI in their families, we estimated the relative risk of MI in parents of HIV-infected individuals.</p> <p>Methods</p> <p>From the Danish HIV Cohort Study and the Danish Civil Registration System we identified the parents of all HIV-infected patients born in Denmark after 1952 in whom a Danish born mother was identifiable. For each HIV patient, 4 matched population controls and their parents were identified. Cumulative incidence functions were constructed to illustrate time to first MI of the parents as registered in the Danish National Hospital Registry. Incidence rate ratios (IRR) were estimated by Cox's regression analyses. Due to the confidential type of the analysed data the study was approved by the Danish Data Protection Agency.</p> <p>Results</p> <p>2,269 mothers and 2,022 fathers of HIV patients as well as 9,076 mothers and 8,460 fathers of control subjects were identified. We observed an increased risk of MI in mothers of HIV patients (adjusted IRR, 1.31; 95% CI: 1.08-1.60). The strongest association was seen in case the offspring was infected heterosexually (adjusted IRR, 1.59; 95% CI: 1.07-2.35) or by IV drug abuse (IVD) (adjusted IRR, 1.63; 95% CI: 1.02-2.60). In fathers of HIV patients the risk of MI was only increased if the offspring was infected by IVD (adjusted IRR, 1.42; 95% CI: 1.01-2.00).</p> <p>Conclusion</p> <p>Mothers of HIV-infected patients have an increased risk of MI. We presume that this stems from family related life style risk factors, some of which may also influence the risk of MI in HIV-infected patients.</p
Low immunogenicity of quadrivalent meningococcal vaccines in solid organ transplant recipients.
International audienceImmunization against meningococcal disease is recommended for solid organ transplant (SOT) recipients at high risk for meningococcal disease or travelling to an endemic country. However, the immunogenicity of meningococcal vaccines has not been studied in this population. We analyzed the immune response of quadrivalent (against Neisseria meningitidis serogroups A, C, Y, and W) polysaccharidic non-conjugate and conjugate meningococcal vaccines in kidney- and liver-transplant patients using bactericidal assays against the targeted serogroups. Upon vaccination with a non-conjugate (n = 5) or a conjugate vaccine (n = 10), respectively, 40% and 50% of patients were able to mount an immune response, achieving at least the threshold correlated with protection defined as human serum bactericidal antibody titers of â„4. Responders showed only partial and low responses (titers â€64), thus predicting a rapid decline in bactericidal response. Only 1 patient developed a booster response to preexisting immunity. Our data argue for the need of additional measures for SOT recipients, when they are at risk of meningococcal disease
Clearance of carbapenem-resistant Enterobacteriaceae vs vancomycin-resistant enterococci carriage after faecal microbiota transplant: a prospective comparative study
International audienc