1,002 research outputs found
A case of multiple sclerosis—like relapsing remitting encephalomyelitis following allogeneic hematopoietic stem cell transplantation and a review of the published literature
Complications involving the central nervous system (CNS) occur in 9–14% of patients following allogeneic hematopoietic stem cell transplantation (HSCT), including stroke-like episodes, demyelination, encephalitis, and nonspecific neurological symptoms. Here we report a case of multiple sclerosis (MS) like relapsing remitting encephalomyelitis following allogeneic HSCT, which did not respond to disease modifying therapies (DMTs) and “domino” autologous HSCT. A 53-year-old male was treated with allogeneic HSCT for lymphoid blast transformation of chronic myeloid leukemia. Ten months later he presented with confusion, slurred speech, left sided facial weakness and ataxia. A magnetic resonance imaging brain scan showed multiple enhancing tumefactive lesions. Neuromyelitis optica (NMO) and myelin oligodendrocyte glycoprotein (MOG) antibodies were negative. After extensive investigations for infections, autoimmune disorders and recurrence of malignancy, he underwent brain biopsy, which showed a macrophage rich lesion with severe myelin loss but axonal preservation indicating a demyelinating pathology. Although his symptoms improved with corticosteroids, he relapsed five months later. In the absence of any systemic features suggesting graft versus host disease (GvHD), his presentation was thought to be compatible with MS. The illness followed an aggressive course that did not respond to glatiramer acetate and natalizumab. He was therefore treated with “domino” autologous HSCT, which also failed to induce long-term remission. Despite further treatment with ocrelizumab, he died of progressive disease. An autopsy limited to the examination of brain revealed multifocal destructive leukoencephalopathy with severe myelin and axonal loss. Immunohistochemistry showed macrophage located in the perivascular area, with no T or B lymphocytes. The appearance was unusual and not typical for chronic MS plaques. Reported cases of CNS demyelination following allogeneic HSCT are very limited in the literature, especially in relation to histopathological examination. Although the clinical disease course of our patient following allogeneic HSCT resembled an “MS-like” relapsing remitting encephalomyelitis, the autopsy examination did not show any evidence of active inflammation. The impact of DMTs and HSCT on the histological appearance of “MS-like” CNS pathologies is unknown. Therefore, reporting this and similar cases will improve our awareness and understanding of underlying disease mechanisms
The DRIFT Dark Matter Experiments
The current status of the DRIFT (Directional Recoil Identification From
Tracks) experiment at Boulby Mine is presented, including the latest limits on
the WIMP spin-dependent cross-section from 1.5 kg days of running with a
mixture of CS2 and CF4. Planned upgrades to DRIFT IId are detailed, along with
ongoing work towards DRIFT III, which aims to be the world's first 10 m3-scale
directional Dark Matter detector.Comment: Proceedings of the 3rd International conference on Directional
Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10 June 201
Provision of long-term monitoring and late effects services following adult allogeneic haematopoietic stem cell transplant: a survey of UK NHS-based programmes
Despite international guidelines, optimal delivery models of late effects (LE) services for HSCT patients are unclear from the clinical, organizational and economic viewpoints. To scope current LE service delivery models within the UK NHS (National Health Service), in 2014, we surveyed the 27 adult allogeneic HSCT centres using a 30-question online tool, achieving a 100% response rate. Most LE services were led and delivered by senior physicians (>80% centres). Follow-up was usually provided in a dedicated allograft or LE clinic for the first year (>90% centres), but thereafter attrition meant that only ~50% of patients were followed after 5 years. Most centres (69%) had a standard operating procedure for long-term monitoring but access to a LE Multi-Disciplinary Team was rare (19% centres). Access to medical specialities necessary for LE management was good, but specialist interest in long-term HSCT complications was uncommon. Some screening (endocrinopathy, cardiovascular) was near universal, but other areas were more limited (mammography, cervical smears). Funding of extra staff and investigations were the most commonly perceived barriers to implementation of LE services. This survey shows variation in the long-term follow-up of allogeneic HSCT survivors within the UK NHS and further work is warranted to optimize effective, sustainable and affordable models of LE service delivery among this group
Charge amplification concepts for direction-sensitive dark matter detectors
Direction measurement of weakly interacting massive particles in
time-projection chambers can provide definite evidence of their existence and
help to determine their properties. This article demonstrates several concepts
for charge amplification in time-projection chambers that can be used in
direction-sensitive dark matter search experiments. We demonstrate
reconstruction of the 'head-tail' effect for nuclear recoils above 100keV, and
discuss the detector performance in the context of dark matter detection and
scaling to large detector volumes.Comment: 15 pages, 9 figure
The large-scale shock in the cluster of galaxies Hydra A
We analyzed a deep XMM-Newton observation of the cluster of galaxies Hydra A,
focusing on the large-scale shock discovered as a surface brightness
discontinuity in Chandra images. The shock front can be seen both in the
pressure map and in temperature profiles in several sectors. The Mach numbers
determined from the temperature jumps are in good agreement with the Mach
numbers derived from EPIC/pn surface brightness profiles and previously from
Chandra data and are consistent with M~1.3. The estimated shock age in the
different sectors using a spherically symmetric point explosion model ranges
between 130 and 230 Myr and the outburst energy between 1.5 and 3e61 ergs. The
shape of the shock seen in the pressure map can be approximated with an ellipse
centered 70 kpc towards the NE from the cluster center. We aimed to develop a
better model that can explain the offset between the shock center and the AGN
and give a consistent result on the shock age and energy. To this end, we
performed 3D hydrodynamical simulations in which the shock is produced by a
symmetrical pair of AGN jets launched in a spherical galaxy cluster. As an
explanation of the observed offset of the shock center, we consider large-scale
bulk flows in the intracluster medium. The simulation successfully reproduces
the size, ellipticity, and average Mach number of the observed shock front. The
predicted age of the shock is 160 Myr and the total input energy 3e61 erg. Both
values are within the range determined by the spherically symmetric model.
Matching the observed 70 kpc offset of the shock ellipse from the cluster
center requires large-scale coherent motions with a high velocity of 670 km/s.
We discuss the feasibility of this scenario and offer alternative ways to
produce the offset and to further improve the simulation.Comment: 14 pages, accepted for publication in A&A, minor revision compared to
previous versio
Suzaku broad-band spectroscopy of RX J1347.5-1145: constraints on the extremely hot gas and non-thermal emission
We present the results from the analysis of long Suzaku observations of the
most X-ray luminous galaxy cluster RX J1347.5-1145 at z=0.451. Aims: We study
physical properties of the hot (~20 keV) gas clump in the south-east (SE)
region discovered by the Sunyaev-Zel'dovich (SZ) effect observations, to
understand the gas physics of a violent cluster merger. We also explore a
signature of non-thermal emission using the hard X-ray data. Results: We find
that the single-temperature model fails to reproduce the continuum emission and
Fe-K lines measured by XIS simultaneously. The two-temperature model with a
very hot component improves the fit, although the XIS data can only give a
lower bound on its temperature. We detect the hard X-ray emission in the 12-40
keV band at the 7 sigma level; however, the significance becomes marginal when
the systematic error in the background estimation is included. With the Suzaku
+ Chandra joint analysis, we determine the temperature of the SE excess
component to be 25.3^{+6.1}_{-4.5} ^{+6.9}_{-9.5} keV (90% statistical and
systematic errors), which is in an excellent agreement with the previous SZ +
X-ray analysis. This is the first time that the X-ray spectroscopy alone gives
a good measurement of the temperature of the hot component in the SE region,
which is made possible by Suzaku's unprecedented sensitivity to the wide X-ray
band. These results strongly indicate that the cluster has undergone a recent,
violent merger. The spectral analysis shows that the SE component is consistent
with being thermal. We find the 3 sigma upper limit on the non-thermal flux, F
< 8e-12 erg s^{-1} cm^{-2} in the 12-60 keV band. Combining this limit with a
recent discovery of the radio mini halo at 1.4 GHz, we find a lower limit on
the strength of the intracluster magnetic field, B > 0.007 micro G.Comment: 15 pages, 13 figures. Accepted for publication in A&
Structural correlations in heterogeneous electron transfer at monolayer and multilayer graphene electrodes
As a new form of carbon, graphene is attracting intense interest as an electrode material with widespread applications. In the present study, the heterogeneous electron transfer (ET) activity of graphene is investigated using scanning electrochemical cell microscopy (SECCM), which allows electrochemical currents to be mapped at high spatial resolution across a surface for correlation with the corresponding structure and properties of the graphene surface. We establish that the rate of heterogeneous ET at graphene increases systematically with the number of graphene layers, and show that the stacking in multilayers also has a subtle influence on ET kinetics. © 2012 American Chemical Society
Suzaku measurement of Abell 2204's intracluster gas temperature profile out to 1800 kpc
Context: Measurements of intracluster gas temperatures out to large radii are
important for the use of clusters for precision cosmology and for studies of
cluster physics. Previous attempts to measure robust temperatures at cluster
virial radii failed. Aims: The goal of this work is to measure the temperature
profile of the very relaxed galaxy cluster Abell 2204 out to large radii,
possibly reaching the virial radius. Methods: Taking advantage of its low
particle background due to its low-Earth orbit, Suzaku data are used to measure
the outer temperature profile of Abell 2204. These data are combined with
Chandra and XMM-Newton data of the same cluster in order to make the connection
to the inner regions, unresolved by Suzaku, and to determine the smearing due
to Suzaku's PSF. Results: The temperature profile of Abell 2204 is determined
from 10 kpc to 1800 kpc, close to an estimate of r200 (the approximation to the
virial radius). The temperature rises steeply from below 4 keV in the very
center up to more than 8 keV in the intermediate range and then decreases again
to about 4 keV at the largest radii. Varying the measured particle background
normalization artificially by +-10 percent does not change the results
significantly. Predictions for outer temperature profiles based on hydrodynamic
simulations show good agreement. In particular, we find the observed
temperature profile to be slightly steeper but consistent with a drop of a
factor of 0.6 from 0.3 r200 to r200, as predicted by simulations. Conclusions:
Temperature measurements up to the virial radius seem feasible with Suzaku,
when a careful analysis of the different background components and the effects
of the PSF is performed. The result obtained here indicates that numerical
simulations capture the intracluster gas physics well in cluster outskirts.Comment: 7 pages; Astronomy and Astrophysics, accepted; additional systematic
effects have been quantified, results unchanged; also available at
http://www.reiprich.ne
Unique Signature of Dark Matter in Ancient Mica
Mica can store (for >1 Gy) etchable tracks caused by atoms recoiling from
WIMPs. Because a background from fission neutrons will eventually limit this
technique, a unique signature for WIMPs in ancient mica is needed. Our motion
around the center of the Galaxy causes WIMPs, unlike neutrons, to enter the
mica from a preferred direction on the sky. Mica is a directional detector and
despite the complex rotations that natural mica crystals make with respect to
this WIMP ``wind,'' there is a substantial dependence of etch pit density on
present day mica orientation.Comment: 5 pages, LaTeX, 2 figures. Accepted for publication at Phys. Rev.
Let
The Imprint of Galaxy Formation on X-ray Clusters
It is widely believed that structure in the Universe evolves hierarchically,
as primordial density fluctuations, amplified by gravity, collapse and merge to
form progressively larger systems. The structure and evolution of X-ray
clusters, however, seems at odds with this hierarchical scenario for structure
formation. Poor clusters and groups, as well as most distant clusters detected
to date, are substantially fainter than expected from the tight relations
between luminosity, temperature and redshift predicted by these models. Here we
show that these discrepancies arise because, near the centre, the entropy of
the hot, diffuse intracluster medium (ICM) is higher tha possible if the ICM
is heated at modest redshift (z \ltsim 2) but prior to cluster collapse,
indicating that the formation of galaxies precedes that of clusters and that
most clusters have been assembled very recently.Comment: 5 pages, plus 2 postscript figures (one in colour), accepted for
publication in Natur
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