62 research outputs found
Circular Dichroism is Sensitive to Monovalent Cation Binding in Monensin Complexes
We present a lock-free version of the light-weight userlevel task management library called Wool, in an aim to show that even extremely well tuned, in terms of synchronization,applications can benefit from lock-free programming.Explicit multi-threading is an efficient way to exploit the offered parallelism of multi-core and multi-processor based systems. However, it can sometimes be hard to expressthe inherited parallelism in programs using a limited number of long lived threads. Often it can be more straightforwardto dynamically create a large number of small tasks that in turn automatically execute on the available threads.Wool is a promising and efficient library and framework that allows the programmer to create user tasks in C with a very low overhead. The library automatically executestasks and balances the load evenly on a given number of threads by utilizing work stealing techniques. However, thesynchronization for stealing tasks is based on mutual exclusion which is known to limit parallelism and efficiency. We have designed and implemented a new lock-free algorithmfor synchronization of stealing tasks in Wool. Experiments show similar or significantly improved performance on a setof benchmarks executed on a multi-core platform
Dynamical Model for the Zodiacal Cloud and Sporadic Meteors
The solar system is dusty, and would become dustier over time as asteroids
collide and comets disintegrate, except that small debris particles in
interplanetary space do not last long. They can be ejected from the solar
system by Jupiter, thermally destroyed near the Sun, or physically disrupted by
collisions. Also, some are swept by the Earth (and other planets), producing
meteors. Here we develop a dynamical model for the solar system meteoroids and
use it to explain meteor radar observations. We find that the Jupiter Family
Comets (JFCs) are the main source of the prominent concentrations of meteors
arriving to the Earth from the helion and antihelion directions. To match the
radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar
(CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets,
and JFCs in particular, must frequently disintegrate when reaching orbits with
low perihelion distance. Also, the collisional lifetimes of millimeter
particles may be longer (>10^5 yr at 1 AU) than postulated in the standard
collisional models (10^4 yr at 1 AU), perhaps because these chondrule-sized
meteoroids are stronger than thought before. Using observations of the Infrared
Astronomical Satellite (IRAS) to calibrate the model, we find that the total
cross section and mass of small meteoroids in the inner solar system are
(1.7-3.5)x10^11 km^2 and 4x10^19 g, respectively, in a good agreement with
previous studies. The mass input required to keep the Zodiacal Cloud (ZC) in a
steady state is estimated to be 10^4-10^5 kg/s. The input is up to 10 times
larger than found previously, mainly because particles released closer to the
Sun have shorter collisional lifetimes, and need to be supplied at a faster
rate
Metrology for the mobile detection of ionising radiation following a nuclear or radiological incident - âPreparednessâ
Postprint (published version
MBM 12: young protoplanetary discs at high galactic latitude
(abridged) We present Spitzer infrared observations to constrain disc and
dust evolution in young T Tauri stars in MBM 12, a star-forming cloud at high
latitude with an age of 2 Myr and a distance of 275 pc. The region contains 12
T Tauri systems, with primary spectral types between K3 and M6; 5 are weak-line
and the rest classical T Tauri stars. We first use MIPS and literature
photometry to compile spectral energy distributions for each of the 12 members
in MBM 12, and derive their IR excesses. The IRS spectra are analysed with the
newly developed two-layer temperature distribution (TLTD) spectral
decomposition method. For the 7 T Tauri stars with a detected IR excess, we
analyse their solid-state features to derive dust properties such as
mass-averaged grain size, composition and crystallinity. We find a spatial
gradient in the forsterite to enstatite range, with more enstatite present in
the warmer regions. The fact that we see a radial dependence of the dust
properties indicates that radial mixing is not very efficient in the discs of
these young T Tauri stars. The SED analysis shows that the discs in MBM 12, in
general, undergo rapid inner disc clearing, while the binary sources have
faster discevolution. The dust grains seem to evolve independently from the
stellar properties, but are mildly related to disc properties such as flaring
and accretion rates.Comment: 14 pages, accepted by Astronomy and Astrophysic
Hereditary thrombotic thrombocytopenic purpura and COVID-19: Impacts of vaccination and infection in this rare disease.
Introduction
Severe COVID-19 is associated with an important increase of von Willebrand factor and mild lowering of ADAMTS13 activity that may, in the presence of a strong inflammatory reaction, increase the risk of acute thrombotic thrombocytopenic purpura (TTP). Although acute episodes of immune-mediated TTP associated with COVID-19 or SARS-CoV-2 vaccination have been reported, data about clinical evolution of hereditary TTP (hTTP) during the pandemic are scarce.
Method
We conducted a survey among adult patients of the International Hereditary TTP Registry about SARS-CoV-2 vaccination, COVID-19, and occurrence of acute hTTP episodes.
Results
Of 122 adult hTTP patients invited to participate, 86 (70.5%) responded. Sixty-five had been vaccinated (75.6%), of which 14 had received in addition a booster, resulting in 139 individual vaccine shots. Although vaccinations in patients on plasma prophylaxis were done within 1âweek of the last plasma infusion, all 23 patients treated with plasma on demand were vaccinated without prior plasma infusions. One patient on uninterrupted weekly plasma infusions presented within 3âdays from his second vaccination with neurological symptoms and computed tomography scan 9âdays later showed subacute ischemic/hemorrhagic frontal lobe infarction. A second male patient developed acute myocarditis after his second dose of mRNA-1273 vaccine. Twelve (14%) patients had COVID-19, associated with an acute hTTP episode in three of them: one patient had a transient ischemic attack, one a stroke, and a pregnant woman was hospitalized to intensify plasma treatment.
Discussion
The risk of an acute episode triggered by COVID-19 seems higher than following vaccination in hTTP patients, who can be safely vaccinated against SARS-CoV-2
Workplace Health Promotion and Mental Health: Three-Year Findings from Partnering Healthy@Work
This study aimed to investigate the association between mental health and comprehensive workplace health promotion (WHP) delivered to an entire state public service workforce (~28,000 employees) over a three-year period. Government departments in a state public service were supported to design and deliver a comprehensive, multi-component health promotion program, Healthy@Work, which targeted modifiable health risks including unhealthy lifestyles and stress. Repeated cross-sectional surveys compared self-reported psychological distress (Kessler-10; K10) at commencement (N = 3406) and after 3 years (N = 3228). WHP availability and participation over time was assessed, and associations between the K10 and exposure to programs estimated. Analyses were repeated for a cohort subgroup (N = 580). Data were weighted for non-response. Participation in any mental health and lifestyle programs approximately doubled after 3 years. Both male and female employees with poorer mental health participated more often over time. Women's psychological distress decreased over time but this change was only partially attributable to participation in WHP, and only to lifestyle interventions. Average psychological distress did not change over time for men. Unexpectedly, program components directly targeting mental health were not associated with distress for either men or women. Cohort results corroborated findings. Healthy@Work was successful in increasing participation across a range of program types, including for men and women with poorer mental health. A small positive association of participation in lifestyle programs with mental health was observed for women but not men. The lack of association of mental health programs may have reflected program quality, its universality of application or other contextual factors
Global patterns and drivers of alpine plant species richness
Aim Alpine ecosystems differ in area, macroenvironment and biogeographical history across the Earth, but the relationship between these factors and plant species richness is still unexplored. Here, we assess the global patterns of plant species richness in alpine ecosystems and their association with environmental, geographical and historical factors at regional and community scales. Location Global. Time period Data collected between 1923 and 2019. Major taxa studied Vascular plants. Methods We used a dataset representative of global alpine vegetation, consisting of 8,928 plots sampled within 26 ecoregions and six biogeographical realms, to estimate regional richness using sampleâbased rarefaction and extrapolation. Then, we evaluated latitudinal patterns of regional and community richness with generalized additive models. Using environmental, geographical and historical predictors from global raster layers, we modelled regional and community richness in a mixedâeffect modelling framework. Results The latitudinal pattern of regional richness peaked around the equator and at midâlatitudes, in response to current and past alpine area, isolation and the variation in soil pH among regions. At the community level, species richness peaked at midâlatitudes of the Northern Hemisphere, despite a considerable withinâregion variation. Community richness was related to macroclimate and historical predictors, with strong effects of other spatially structured factors. Main conclusions In contrast to the wellâknown latitudinal diversity gradient, the alpine plant species richness of some temperate regions in Eurasia was comparable to that of hyperdiverse tropical ecosystems, such as the pĂĄramo. The species richness of these putative hotspot regions is explained mainly by the extent of alpine area and their glacial history, whereas community richness depends on local environmental factors. Our results highlight hotspots of species richness at midâlatitudes, indicating that the diversity of alpine plants is linked to regional idiosyncrasies and to the historical prevalence of alpine ecosystems, rather than current macroclimatic gradients
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
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