387 research outputs found
Silica-waveguide thermooptic phase shifter with low power consumption and low lateral heat diffusion
INTEGRAL long-term monitoring of the Supergiant Fast X-ray Transient XTE J1739-302
In the past few years, a new class of High Mass X-Ray Binaries (HMXRB) has
been claimed to exist, the Supergiant Fast X-ray Transients (SFXT). These are
X-ray binary systems with a compact companion orbiting a supergiant star which
show very short and bright outbursts in a series of activity periods
overimposed on longer quiescent periods. Only very recently the first attempts
to model the behaviour of these sources have been published, some of them
within the framework of accretion from clumpy stellar winds.Our goal is to
analyze the properties of XTE J1739-302/IGR J17391-3021 within the context of
the clumpy structure of the supergiant wind. We have used INTEGRAL and RXTE/PCA
observations in order to obtain broad band (1-200 keV) spectra and light curves
of XTE J1739-302 and investigate its X-ray spectrum and temporal variability.
We have found that XTE J1739-302 follows a much more complex behaviour than
expected. Far from presenting a regular variability pattern, XTE J1739-302
shows periods of high, intermediate, and low flaring activity.Comment: 9 pages, 7 figures, accepted for publication in A&
Low-Bandwidth and Non-Compute Intensive Remote Identification of Microbes from Raw Sequencing Reads
Cheap high-throughput DNA sequencing may soon become routine not only for
human genomes but also for practically anything requiring the identification of
living organisms from their DNA: tracking of infectious agents, control of food
products, bioreactors, or environmental samples.
We propose a novel general approach to the analysis of sequencing data in
which the reference genome does not have to be specified. Using a distributed
architecture we are able to query a remote server for hints about what the
reference might be, transferring a relatively small amount of data, and the
hints can be used for more computationally-demanding work.
Our system consists of a server with known reference DNA indexed, and a
client with raw sequencing reads. The client sends a sample of unidentified
reads, and in return receives a list of matching references known to the
server. Sequences for the references can be retrieved and used for exhaustive
computation on the reads, such as alignment.
To demonstrate this approach we have implemented a web server, indexing tens
of thousands of publicly available genomes and genomic regions from various
organisms and returning lists of matching hits from query sequencing reads. We
have also implemented two clients, one of them running in a web browser, in
order to demonstrate that gigabytes of raw sequencing reads of unknown origin
could be identified without the need to transfer a very large volume of data,
and on modestly powered computing devices.
A web access is available at http://tapir.cbs.dtu.dk. The source code for a
python command-line client, a server, and supplementary data is available at
http://bit.ly/1aURxkc
Translating the multi-actor approach to research into practice using a workshop approach focusing on species mixtures
The EIP-Agri multiactor approach was exemplified during a 3-day workshop with 63 project participants from the EU H2020 funded project "Redesigning European cropping systems based on species MIXtures". The objective was to share firsthand experience of participatory research among researchers who were mostly not familiar with this approach. Workshop participants were divided into smaller multidisciplinary groups and given the opportunity to interact with representatives from eight actor positions in the value chain of the agrifood cooperative Terrena located in Western France. The four stages of the workshop were: (1) key actor interviews, (2) sharing proposed solutions for overcoming barriers, and (3) developing possible interdisciplinary concepts. Expressions of frustration were recorded serving both as a motivation for group members to become more aware of the scientific concerns and practices of their colleagues, as well as a recognition that some researchers have better skills integrating qualitative approaches than others. Nevertheless, the workshop format was an effective way to gain a common understanding of the pertinent issues that need to be addressed to meet overall multiactor-approach objectives. Working with the actor networks was identified and emphasized as a means to overcome existing barriers between academia and practice in order to coproduce a shared vision of the benefits of species mixture benefits. (C) The Author(s) 2021. Published by Higher Education Press
MicroRNA regulation of endothelial homeostasis and commitment—implications for vascular regeneration strategies using stem cell therapies
Human embryonic (hESC) and induced pluripotent (hiPSC) stem cells have broad therapeutic potential in the treatment of a range of diseases, including those of the vascular system. Both hESCs and hiPSCs have the capacity for indefinite self-renewal, in addition to their ability to differentiate into any adult cell type. These cells could provide a potentially unlimited source of cells for transplantation and, therefore, provide novel treatments, e.g. in the production of endothelial cells for vascular regeneration. MicroRNAs are short, noncoding RNAs that act posttranscriptionally to control gene expression and thereby exert influence over a wide range of cellular processes, including maintenance of pluripotency and differentiation. Expression patterns of these small RNAs are tissue specific, and changes in microRNA levels have often been associated with disease states in humans, including vascular pathologies. Here, we review the roles of microRNAs in endothelial cell function and vascular disease, as well as their role in the differentiation of pluripotent stem cells to the vascular endothelial lineage. Furthermore, we discuss the therapeutic potential of stem cells and how knowledge and manipulation of microRNAs in stem cells may enhance their capacity for vascular regeneration
The INTEGRAL Galactic bulge monitoring program: the first 1.5 years
The Galactic bulge region is a rich host of variable high-energy point
sources. Since 2005, February 17 we are monitoring the source activity in this
region about every three days with INTEGRAL. Thanks to the large field of view,
the imaging capabilities and the sensitivity at hard X-rays, we are able to
present for the first time a detailed homogeneous (hard) X-ray view of a sample
of 76 sources in the Galactic bulge region. We describe the successful
monitoring program and show the first results for a period of about one and a
half year. We focus on the short (hour), medium (month) and long-term (year)
variability in the 20-60 keV and 60-150 keV bands. When available, we discuss
the simultaneous observations in the 3-10 keV and 10-25 keV bands. Per
visibility season we detect 32/33 sources in the 20-60 keV band and 8/9 sources
in the 60-150 keV band. On average, we find per visibility season one active
bright (>~100 mCrab, 20-60 keV) black-hole candidate X-ray transient and three
active weaker (<~25 mCrab, 20-60 keV) neutron star X-ray transients. Most of
the time a clear anti-correlation can be seen between the soft and hard X-ray
emission in some of the X-ray bursters. Hard X-ray flares or outbursts in X-ray
bursters, which have a duration of the order of weeks, are accompanied by soft
X-ray drops. On the other hand, hard X-ray drops can be accompanied by soft
X-ray flares/outbursts. We found a number of new sources, IGR J17354-3255, IGR
17453-2853, IGR J17454-2703, IGR J17456-2901b, IGR J17536-2339, and IGR
J17541-2252. We report here on some of the high-energy properties of these
sources. The high-energy light curves of all the sources in the field of view,
and the high-energy images of the region, are made available through the WWW at
http://isdc.unige.ch/Science/BULGE/.Comment: 27 pages, 42 figures, accepted for publication in A&A. Abstract
abridged. Tables 3,4,6,7 appear at the end. Images have been compressed and
are reduced in quality; original PostScript images can be retrieved from
http://isdc.unige.ch/~kuulkers/bulge
Tidal Dissipation in the Early Eocene and Implications for Ocean Mixing
The tidally driven vertical diffusivity in the abyssal ocean during the early Eocene (55 Ma) is investigated using an established tidal model. A weak tide is predicted in the Eocene ocean, except in the Pacific. Consequently, the integrated global tidal dissipation rate is a mere 1.44TW, of which 40% dissipate in the Pacific. However, due to a stronger abyssal vertical stratification the predicted Eocene vertical diffusivities are consistently larger than at present. The results support the hypothesis that altered tidal dissipation may play a role in explaining the maintenance of past climate regimes, especially the anomalously warm temperatures in the southwest Pacific in the Eocene, and the low dissipation rates may be important for lunar evolution history
High-energy observations of the state transition of the X-ray nova and black hole candidate XTE J1720-318
We report the results of extensive high-energy observations of the X-ray
transient and black hole candidate XTE J1720-318 performed with INTEGRAL,
XMM-Newton and RXTE. The source, which underwent an X-ray outburst in 2003
January, was observed in February in a spectral state dominated by a soft
component with a weak high-energy tail. The XMM-Newton data provided a high
column density Nh of 1.2*e22 cm^{-2} which suggests that the source lies at the
Galactic Centre distance. The simultaneous RXTE and INTEGRAL Target of
Opportunity observations allowed us to measure the weak and steep tail, typical
of a black-hole binary in the so-called High/Soft State. We then followed the
evolution of the source outburst over several months using the INTEGRAL
Galactic Centre survey observations. The source became active again at the end
of March: it showed a clear transition towards a much harder state, and then
decayed to a quiescent state after April. In the hard state, the source was
detected up to 200 keV with a power law index of 1.9 and a peak luminosity of
7*e36 erg s^{-1} in the 20-200 keV band, for an assumed distance of 8 kpc. We
conclude that XTE J1720-318 is indeed a new member of the black hole X-ray
novae class which populate our galactic bulge and we discuss its properties in
the frame of the spectral models used for transient black hole binaries.Comment: 10 pages, 7 figures, 2 tables, Accepted for publication in Astronomy
& Astrophysic
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
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