619 research outputs found
Testing reflection features in 4U 1705-44 with XMM-Newton, BeppoSAX and RXTE in the hard and soft state
We use data of the bright atoll source 4U 1705-44 taken with XMM-Newton,
BeppoSAX and RXTE both in the hard and in the soft state to perform a
self-consistent study of the reflection component in this source. Although the
data from these X-ray observatories are not simultaneous, the spectral
decomposition is shown to be consistent among the different observations, when
the source flux is similar. We therefore select observations performed at
similar flux levels in the hard and soft state in order to study the spectral
shape in these two states in a broad band (0.1-200 keV) energy range, with good
energy resolution, and using self-consistent reflection models. These
reflection models provide a good fit for the X-ray spectrum both in the hard
and in the soft state in the whole spectral range. We discuss the differences
in the main spectral parameters we find in the hard and the soft state,
respectively, providing evidence that the inner radius of the optically thick
disk slightly recedes in the hard state.Comment: Accepted for publication in A&A, 20 pages, 12 figure
Mononeuritis multiplex: an uncommon neurological manifestation of cytomegalovirus reactivation in an HIV-infected patient
BACKGROUND: Cytomegalovirus (CMV) reactivation with neurological involvement in patients with acquired immunodeficiency syndrome (AIDS) is increasingly rare since the introduction of antiretroviral therapy (ART). Manifestations include encephalitis, myelitis, polyradiculopathy and, less commonly, mononeuritis multiplex (MNM). We report a case of disseminated CMV disease with gastrointestinal and peripheral and central nervous system involvement in a patient with AIDS, manifesting primarily as MNM. CASE PRESENTATION: A 31-year old woman with AIDS presented with a clinical picture of MNM. Electromyography confirmed the clinical findings. CMV DNA was detected in cerebrospinal fluid (CSF) and blood. Gastrointestinal involvement was histologically documented. HIV RNA was also detected in CSF and brain MRI was consistent with HIV encephalopathy. A diagnosis of disseminated CMV disease (with esophagitis, colitis, encephalitis and MNM) and HIV encephalopathy was made. Treatment consisted of ganciclovir and foscarnet, followed by maintenance therapy with valganciclovir. Evolution was favorable and valganciclovir was stopped after sustained immune recovery following ART initiation. CONCLUSION: We discuss the diagnostic approach to CMV neurological disease, with a focus on MNM and CMV encephalitis. Combination therapy with ganciclovir and foscarnet should be considered for all forms of neurological involvement, although available data are scarce. Since there is significant overlap between CMV encephalitis and HIV encephalopathy, ART drugs with higher CSF penetration may have to be considered. ART and immune recovery are essential to improve outcomes
Burning in the management of heathlands of Erica ciliaris and Erica tetralix: effects on structure and diversity
Can controlled burning be used as a management tool of Erica ciliaris and Erica tetralix wet heathlands?
Two E. ciliaris and E. tetralix communities were selected and two 5 x 5 m plots were established in each.
These were then characterised on the basis of frequency and cover values and plant species composition. They
were subjected to experimental burning, after which the plots were sampled twice a year during the following
four and a half years. The results show that the cover of woody species very quickly attained the values of the
Control Plots. Diversity and species composition did not suffer notable changes during this period, however,
temporal heterogeneity indicates that the main changes occur in the first 18 months of secondary succession.
The multivariate analysis showed that the samples registered during this time were grouped as a function of
the cover values of the species, which shows that stages exist in the vegetation recovery of these communities.
The damage produced by fire in the community is minor, as a rapid recovery of the vegetation was observed, so
controlled burning is a useful tool in the management of these heathlands
Misdiagnosis of familial Mediterranean fever in patients with Anderson-Fabry disease
Fabry disease (FD) is an underdiagnosed pathology due to its symptomatology that
overlaps with various systemic and rheumatic disorders, including familial
Mediterranean fever (FMF). We examined the Mediterranean fever (MEFV) and
α-galactosidase A (GLA) genes, whose mutations are responsible for FMF and FD,
respectively, in 42 unrelated patients diagnosed with FMF, which revealed
significant ambiguity regarding some of the symptoms which are also present in
FD. The objective of this study was to determine the spectrum of mutations
present in these genes, in order to identify cases of mistaken diagnosis of FMF
and/or missed diagnosis of FD. Ten out of 42 patients had one mutation in
homozygosis or two different mutations in heterozygosis in the MEFV gene; 20/42
had a single heterozygous mutation, and 12/42 did not have genetic alterations in
MEFV. The analysis of the GLA gene conducted on all the samples revealed that
three subjects, and some members of their families, had two different exonic
mutations associated with FD. Family studies allowed us to identify eight other
cases of FD, bringing the total undiagnosed subjects to 11/53. Analyzing the MEFV
and GLA genes in patients with clinical diagnoses of FMF proved to be
fundamentally important for the reduction of diagnostic errors
Collaborative Multi-Objective Optimization for Distributed Design of Complex Products
Multidisciplinary design optimization problems with competing
objectives that involve several interacting components can be called
complex systems. Nowadays, it is common to partition the optimization
problem of a complex system into smaller subsystems,
each with a subproblem, in part because it is too difficult to deal
with the problem all-at-once. Such an approach is suitable for large
organisations where each subsystem can have its own (specialised)
design team. However, this requires a design process that facilitates
collaboration, and decision making, in an environment where
teams may exchange limited information about their own designs,
and also where the design teams work at different rates, have different
time schedules, and are normally not co-located. A multiobjective
optimization methodology to address these features is
described. Subsystems exchange information about their own optimal
solutions on a peer-to-peer basis, and the methodology enables
convergence to a set of optimal solutions that satisfy the overall
system. This is demonstrated on an example problem where the
methodology is shown to perform as well as the ideal, but “unrealistic”
approach, that treats the optimization problem all-at-once
A distributed multi-disciplinary design optimization benchmark test suite with constraints and multiple conflicting objectives
Collaborative optimization (CO) is an architecture within the multi-disciplinary design optimization (MDO) paradigm that partitions a constrained optimization problem into system and subsystem problems, with couplings between them. Multi-objective CO has multiple objectives at the system level and inequality constraints at the subsystem level. Whilst CO is an established technique, there are currently no scalable, constrained benchmark problems for multi-objective CO. In this study, we extend recent methods for generating scalable MDO benchmarks to propose a new benchmark test suite for multi-objective CO that is scalable in disciplines and variables, called `CO-ZDT'. We show that overly-constraining the number of generations in each iteration of the system-level optimizer leads to poor consistency constraint satisfaction. Increasing the number of subsystems in each of the problems leads to increasing system-level constraint violation. In problems with two subsystems, we find that convergence to the global Pareto front is very sensitive to the complexity of the landscape of the original non-decomposed problem. As the number of subsystems increases, convergence issues are encountered even for the simpler problem landscapes
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