558 research outputs found
Changes in trabecular bone, hematopoiesis and bone marrow vessels in aplastic anemia, primary osteoporosis, and old age
Retrospective histologic analyses of bone biopsies and of post mortem samples from normal persons of different age groups, and of bone biopsies of age- and sex-matched groups of patients with primary osteoporosis and aplastic anemia show characteristic age dependent as well as pathologic changes including atrophy of osseous trabeculae and of hematopoiesis, and changes in the sinusoidal and arterial capillary compartments. These results indicate the possible role of a microvascular defect in the pathogenesis of osteoporosis and aplastic anemia
The Mystery of the Asymptotic Quasinormal Modes of Gauss-Bonnet Black Holes
We analyze the quasinormal modes of -dimensional Schwarzschild black holes
with the Gauss-Bonnet correction in the large damping limit and show that
standard analytic techniques cannot be applied in a straightforward manner to
the case of infinite damping. However, by using a combination of analytic and
numeric techniques we are able to calculate the quasinormal mode frequencies in
a range where the damping is large but finite. We show that for this damping
region the famous appears in the real part of the quasinormal mode
frequency. In our calculations, the Gauss-Bonnet coupling, , is taken
to be much smaller than the parameter , which is related to the black hole
mass.Comment: 12 pages and 5 figure
Photon emission from bare quark stars
We investigate the photon emission from the electrosphere of a quark star. It
is shown that at temperatures T\sim 0.1-1 MeV the dominating mechanism is the
bremsstrahlung due to bending of electron trajectories in the mean Coulomb
field of the electrosphere. The radiated energy for this mechanism is much
larger than that for the Bethe-Heitler bremsstrahlung. The energy flux from the
mean field bremsstrahlung exceeds the one from the tunnel e^{+}e^{-} pair
creation as well. We demonstrate that the LPM suppression of the photon
emission is negligible.Comment: 35 pages, 5 figure
The Highly Damped Quasinormal Modes of -dimensional Reissner-Nordstrom Black Holes in the Small Charge Limit
We analyze in detail the highly damped quasinormal modes of -dimensional
Reissner-Nordstrm black holes with small charge, paying
particular attention to the large but finite damping limit in which the
Schwarzschild results should be valid. In the infinite damping limit, we
confirm using different methods the results obtained previously in the
literature for higher dimensional Reissner-Nordstrm black holes.
Using a combination of analytic and numerical techniques we also calculate the
transition of the real part of the quasinormal mode frequency from the
Reissner-Nordstrm value for very large damping to the
Schwarzschild value of for intermediate damping. The real
frequency does not interpolate smoothly between the two values. Instead there
is a critical value of the damping at which the topology of the
Stokes/anti-Stokes lines change, and the real part of the quasinormal mode
frequency dips to zero.Comment: 18 pages, 8 figure
Forensic, legal, and clinical aspects of deaths associated with implanted cardiac devices
As the population ages, the prevalence of heart failure and individuals wearing an
implanted cardiac device is increasing. The combination of different underlying
pathophysiologies and (the combination of) implanted cardiac devices can
become a challenge with regard to the determination of cause and manner of
death in such individuals. Additionally, heart disease is frequently associated with
mental disease, ranging from anxiety and depression to suicidality and suicide
(attempts). At the same time, the correct diagnosis of cause and manner of death
is the basis for quality assurance, further therapeutic advances, legal safety, and
suicide prevention. By that, an interdisciplinary field between legal medicine,
clinicians, and law enforcement opens up. In this field, the different participants
can simultaneously benefit from and need each other. For example, legal medicine
experts need investigatory results and clinical expertise for the interpretation of
readout data of implanted cardiac devices in order to correctly determine the
cause of death. A correctly determined cause of death can assist law enforcement
and help clinicians to further improve various therapeutic approaches based on
correct mortality data collection. In addition, it is the basis for identification of
suicides of device carriers, allowing psychological and psychiatric experts to
better understand the burden of mental disease in this particular cohort. Against
this interdisciplinary background, this manuscript summarizes information about
psychiatric comorbidities and suicidality while being on a device. Thereby, basic
information on complications and malfunctions of implanted cardiac devices,
device-associated deaths with particular emphasis on device manipulation is
displayed as basic information needed for correct determination of the cause
of death. Also, legal and ethical issues in this field are outlined. The final result is
a proposal of an interdisciplinary assessment workflow for a conjoint approach
to improve the diagnosis of deaths associated with implanted cardiac devices. It
will allow for a differentiation between an individual who died with or due to the
device
A source of polarized electrons based on photoemission of GaAsP.
The source described is based on photoemission of electrons from 100-GaAs0.62P0.38 activated to negative electron affinity. It is built to inject a beam of polarized electrons into the 350 MeV linear accelerator in Mainz. It is capable of delivering a mean current of 28 μA spin-polarized longitudinally to a degree of 0.44. The lifetime of the cathode under operational conditions is better than 200 h. The source was successfully run in a parity experiment, in which the analysing power of quasielastic scattering from beryllium for longitudinally polarized electrons was measured
Strange Star Heating Events as a Model for Giant Flares of Soft Gamma-ray Repeaters
Two giant flares were observed on 5 March 1979 and 27 August 1998 from the
soft gamma-ray repeaters SGR 0526-66 and SGR 1900+14, respectively. The
striking similarity between these remarkable bursts strongly implies a common
nature. We show that the light curves of the giant bursts may be easily
explained in the model where the burst radiation is produced by the bare quark
surface of a strange star heated, for example, by impact of a massive
comet-like object.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. Letter
Earth Observation to Address Inequities in Post-Flood Recovery
Floods impact communities worldwide, resulting in loss of life, damaged infrastructure and natural assets, and threatened livelihoods. Climate change and urban development in flood-prone areas will continue to worsen flood-related losses, increasing the urgency for effective tools to monitor recovery. Many Earth Observation (EO) applications exist for flood-hazard monitoring and provide insights on location, timing, and extent in near real-time and historically to estimate flood risk. Less attention has been paid to flood recovery, even though differing recovery rates and outcomes can have immediate and enduring distributional effects within communities. EO data are uniquely positioned to monitor post-flood recovery and inform policy on hazard mitigation and adaptation but remain underutilized. We encourage the EO and flood research community to refocus on developing flood recovery applications to address growing risk. Translation of EO insights on flood recovery among flood-affected communities and decision-makers is necessary to address underlying social vulnerabilities that exacerbate inequitable recovery outcomes and advocate for redressing injustices where disparate recovery is observed. We identify an unequivocal need for EO to move beyond mapping flood hazard and exposure toward post-flood recovery monitoring to inform recovery across geographic contexts. This commentary proposes a framework for remote sensing scientists to engage community-based partners to integrate EO with non-EO data to advance flood recovery monitoring, characterize inequitable recovery, redistribute resources to mitigate inequities, and support risk reduction of future floods
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