547 research outputs found
Fourfold oscillations and anomalous magnetic irreversibility of magnetoresistance in the non-metallic regime of Pr1.85Ce0.15CuO4
Using magnetoresistance measurements as a function of applied magnetic field
and its direction of application, we present sharp angular-dependent
magnetoresistance oscillations for the electron-doped cuprates in their
low-temperature non-metallic regime. The presence of irreversibility in the
magnetoresistance measurements and the related strong anisotropy of the field
dependence for different in-plane magnetic field orientations indicate that
magnetic domains play an important role for the determination of electronic
properties. These domains are likely related to the stripe phase reported
previously in hole-doped cuprates.Comment: 11 pages, 5 figure
Matter-wave laser Interferometric Gravitation Antenna (MIGA): New perspectives for fundamental physics and geosciences
The MIGA project aims at demonstrating precision measurements of gravity with
cold atom sensors in a large scale instrument and at studying the associated
applications in geosciences and fundamental physics. The first stage of the
project (2013-2018) will consist in building a 300-meter long optical cavity to
interrogate atom interferometers and will be based at the low noise underground
laboratory LSBB in Rustrel, France. The second stage of the project (2018-2023)
will be dedicated to science runs and data analyses in order to probe the
spatio-temporal structure of the local gravity field of the LSBB region, a site
of high hydrological interest. MIGA will also assess future potential
applications of atom interferometry to gravitational wave detection in the
frequency band Hz hardly covered by future long baseline optical
interferometers. This paper presents the main objectives of the project, the
status of the construction of the instrument and the motivation for the
applications of MIGA in geosciences. Important results on new atom
interferometry techniques developed at SYRTE in the context of MIGA and paving
the way to precision gravity measurements are also reported.Comment: Proceedings of the 50th Rencontres de Moriond "100 years after GR",
La Thuile (Italy), 21-28 March 2015 - 10 pages, 5 figures, 23 references
version2: added references, corrected typo
Derivation of a high-resolution CT-based, semi-automated radiographic score in tuberculosis and its relationship to bacillary load and antitubercular therapy
Efforts to curb the tuberculosis (TB) pandemic remain hindered by a lack of objective measures to quantify disease severity and track treatment success that are valid in both HIV-1-infected and -uninfected TB patients. Ralph et al. [1] developed a promising radiographic scoring system, with baseline scores being predictive of sputum smear conversion at 2 months, but it is reliant on skilled readers and has not been systematically validated in predominantly HIV-infected study populations with varying CD4 counts. Superior to conventional chest radiography, high-resolution computed tomography (HRCT) is a highly sensitive tool to track endobronchial TB disease extent [2]
A slow gravity compensated Atom Laser
We report on a slow guided atom laser beam outcoupled from a Bose-Einstein
condensate of 87Rb atoms in a hybrid trap. The acceleration of the atom laser
beam can be controlled by compensating the gravitational acceleration and we
reach residual accelerations as low as 0.0027 g. The outcoupling mechanism
allows for the production of a constant flux of 4.5x10^6 atoms per second and
due to transverse guiding we obtain an upper limit for the mean beam width of
4.6 \mu\m. The transverse velocity spread is only 0.2 mm/s and thus an upper
limit for the beam quality parameter is M^2=2.5. We demonstrate the potential
of the long interrogation times available with this atom laser beam by
measuring the trap frequency in a single measurement. The small beam width
together with the long evolution and interrogation time makes this atom laser
beam a promising tool for continuous interferometric measurements.Comment: 7 pages, 8 figures, to be published in Applied Physics
Applying the win ratio method in clinical trials of orphan drugs: an analysis of data from the COMET trial of avalglucosidase alfa in patients with late-onset Pompe disease
Background: Clinical trials for rare diseases often include multiple endpoints that capture the effects of treatment on different disease domains. In many rare diseases, the primary endpoint is not standardized across trials. The win ratio approach was designed to analyze multiple endpoints of interest in clinical trials and has mostly been applied in cardiovascular trials. Here, we applied the win ratio approach to data from COMET, a phase 3 trial in late-onset Pompe disease, to illustrate how this approach can be used to analyze multiple endpoints in the orphan drug context. Methods: All possible participant pairings from both arms of COMET were compared sequentially on changes at week 49 in upright forced vital capacity (FVC) % predicted and six-minute walk test (6MWT). Each participantâs response for the two endpoints was first classified as a meaningful improvement, no meaningful change, or a meaningful decline using thresholds based on published minimal clinically important differences (FVC ± 4% predicted, 6MWT ± 39 m). Each comparison assessed whether the outcome with avalglucosidase alfa (AVA) was better than (win), worse than (loss), or equivalent to (tie) the outcome with alglucosidase alfa (ALG). If tied on FVC, 6MWT was compared. In this approach, the treatment effect is the ratio of wins to losses (âwin ratioâ), with ties excluded. Results: In the 2499 possible pairings (51 receiving AVA Ă 49 receiving ALG), the win ratio was 2.37 (95% confidence interval [CI], 1.30â4.29, p = 0.005) when FVC was compared before 6MWT. When the order was reversed, the win ratio was 2.02 (95% CI, 1.13â3.62, p = 0.018). Conclusion: The win ratio approach can be used in clinical trials of rare diseases to provide meaningful insight on treatment benefits from multiple endpoints and across disease domains
Comparison of open and closed book test for admission in medical school
Introduction
La maladie thromboembolique veineuse (MTEV) acquise Ă lâhĂŽpital reprĂ©sente une part importante de morbi-mortalitĂ© Ă©vitable chez les patients hospitalisĂ©s en secteur mĂ©dical. Dâun autre cĂŽtĂ©, la thromboprophylaxie anticoagulante expose les patients Ă un risque hĂ©morragique et majore les dĂ©penses de santĂ©. Lâidentification des patients hospitalisĂ©s Ă risque de MTEV est en cela cruciale. Lâobjectif de cette Ă©tude est dâĂ©valuer de maniĂšre externe, les performances de 3 modĂšles de risque (score de Padua, Carpini et Improve) et de les comparer aux performances de lâĂąge pris isolĂ©ment.
Patients et méthodes
Il sâagit dâune Ă©tude rĂ©trospective sur une base de patients inclus prospectivement dans une Ă©tude randomisĂ©e en cluster sans intervention directe sur le patient. Les patients de plus de 40 ans, hospitalisĂ© depuis les urgences en secteur mĂ©dical plus de 48 h ont consĂ©cutivement Ă©tĂ© inclus et suivi Ă 3 mois. Les patients chez qui un diagnostic de MTEV avait Ă©tĂ© portĂ© dans les 48 premiĂšres heures dâhospitalisation, ou ayant reçu un traitement anticoagulant pour une raison autre que la MTEV, ou encore ayant subi une chirurgie sous anesthĂ©sie gĂ©nĂ©rale ont Ă©tĂ© exclus. Les modĂšles de risques ont Ă©tĂ© calculĂ©s Ă posteriori. La rĂ©duction de mobilitĂ© a Ă©tĂ© dĂ©duite de la durĂ©e dâhospitalisation moins un jour. Le critĂšre de jugement principal Ă©tait la survenue dâun Ă©pisode thrombotique veineux symptomatique ou le dĂ©cĂšs brutal inexpliquĂ© adjudiquĂ© Ă 3 mois.
RĂ©sultats
Parmi les 14 910 patient Ă©ligibles, 14 659 (98,3) Ă©taient Ă©valuables. 263 (1,8 %) ont prĂ©sentĂ© une MTEV symptomatique ou un dĂ©cĂšs brutal inexpliquĂ©. Les aires sous la courbe ROC Ă©taient respectivement 0,60 [0,57â0,63], 0,62 [0,58â0,64] et 0,62 [0,59â0,65] pour les scores Caprini, Improve et Padua. Aucun de ces modĂšles nâa montrĂ© de performances supĂ©rieures Ă lâĂąge pris isolĂ©ment (AUC 0,61 [0,58â0,64]). Ces rĂ©sultats Ă©taient similaires ne considĂ©rant que les Ă©vĂšnements symptomatiques non fatals : (0,62 [0,58â0,66], 0,62 [0,58â0,66], 0,63 [0,59â0,67] et 0,58 [0,54â0,62]) ; ou dans le sous-groupe de patients ne recevant pas de thromboprophylaxie anticoagulante : 0,62 [0,58â0,67], 0,64 [0,60â0,68], 0,64 [0,59â0,68] et 0,66 [0,62â0,70] pour le score Caprini, Improve, Padua et lâĂąge, respectivement.
Conclusion
Les scores de Padua, Caprini et Improve ont des capacitĂ©s de discrimination faible vis-Ă -vis de la MTEV acquise Ă lâhĂŽpital, similaire Ă une Ă©valuation se basant uniquement sur lâĂąge. Les meilleurs modĂšles de risque sont nĂ©cessaires
Pre-transplant CD45RC expression on blood T cells differentiates patients with cancer and rejection after kidney transplantation
Background
Biological biomarkers to stratify cancer risk before kidney transplantation are lacking. Several data support that tumor development and growth is associated with a tolerant immune profile. T cells expressing low levels of CD45RC preferentially secrete regulatory cytokines and contain regulatory T cell subset. In contrast, T cells expressing high levels of CD45RC have been shown to secrete proinflammatory cytokines, to drive alloreactivity and to predict acute rejection (AR) in kidney transplant patients. In the present work, we evaluated whether pre-transplant CD45RClow T cell subset was predictive of post-transplant cancer occurrence.
Methods
We performed an observational cohort study of 89 consecutive first time kidney transplant patients whose CD45RC T cell expression was determined by flow cytometry before transplantation. Post-transplant events including cancer, AR, and death were assessed retrospectively.
Results
After a mean follow-up of 11.1±4.1 years, cancer occurred in 25 patients (28.1%) and was associated with a decreased pre-transplant proportion of CD4+CD45RChigh T cells, with a frequency below 51.9% conferring a 3.7-fold increased risk of post-transplant malignancy (HR 3.71 [1.24â11.1], p = 0.019). The sensibility, specificity, negative predictive and positive predictive values of CD4+CD45RChigh<51.9% were 84.0, 54.7, 89.8 and 42.0% respectively. Confirming our previous results, frequency of CD8+CD45RChigh T cells above 52.1% was associated with AR, conferring a 20-fold increased risk (HR 21.7 [2.67â176.2], p = 0.0004). The sensibility, specificity, negative predictive and positive predictive values of CD8+CD45RChigh>52.1% were 94.5, 68.0, 34.7 and 98.6% respectively. Frequency of CD4+CD45RChigh T cells was positively correlated with those of CD8+CD45RChigh (p<0.0001), suggesting that recipients with high AR risk display a low cancer risk.
Conclusion
High frequency of CD45RChigh T cells was associated with AR, while low frequency was associated with cancer. Thus, CD45RC expression on T cells appears as a double-edged sword biomarker of promising interest to assess both cancer and AR risk before kidney transplantation
Iwasawa theory and p-adic L-functions over Zp2-extensions
We construct a two-variable analogue of Perrin-Riouâs p-adic regulator map for the Iwasawa cohomology of a crystalline representation of the absolute Galois group of Q p , over a Galois extension whose Galois group is an abelian p-adic Lie group of dimension 2. We use this regulator map to study p-adic representations of global Galois groups over certain abelian extensions of number fields whose localisation at the primes above p is an extension of the above type. In the example of the restriction to an imaginary quadratic field of the representation attached to a modular form, we formulate a conjecture on the existence of a âzeta elementâ, whose image under the regulator map is a p-adic L-function. We show that this conjecture implies the known properties of the 2-variable p-adic L-functions constructed by Perrin-Riou and Kim
An exploratory cluster randomised trial of a university halls of residence based social norms marketing campaign to reduce alcohol consumption among 1st year students
<p>Aims: This exploratory trial examines the feasibility of implementing a social norms marketing campaign to reduce student drinking in universities in Wales, and evaluating it using cluster randomised trial methodology.</p>
<p>Methods: Fifty residence halls in 4 universities in Wales were randomly assigned to intervention or control arms. Web and paper surveys were distributed to students within these halls (nâ=â3800), assessing exposure/contamination, recall of and evaluative responses to intervention messages, perceived drinking norms and personal drinking behaviour. Measures included the Drinking Norms Rating Form, the Daily Drinking Questionnaire and AUDIT-C.</p>
<p>Results: A response rate of 15% (nâ=â554) was achieved, varying substantially between sites. Intervention posters were seen by 80% and 43% of students in intervention and control halls respectively, with most remaining materials seen by a minority in both groups. Intervention messages were rated as credible and relevant by little more than half of students, though fewer felt they would influence their behaviour, with lighter drinkers more likely to perceive messages as credible. No differences in perceived norms were observed between intervention and control groups. Students reporting having seen intervention materials reported lower descriptive and injunctive norms than those who did not.</p>
<p>Conclusions: Attention is needed to enhancing exposure, credibility and perceived relevance of intervention messages, particularly among heavier drinkers, before definitive evaluation can be recommended. A definitive evaluation would need to consider how it would achieve sufficient response rates, whilst hall-level cluster randomisation appears subject to a significant degree of contamination.</p>
Glyphosate and AMPA in human urine of HBM4EU-aligned studies: part B adults
Within HBM4EU, human biomonitoring (HBM) studies measuring glyphosate (Gly) and aminomethylphosphonic acid (AMPA) in urine samples from the general adult population were aligned and quality-controlled/assured. Data from four studies (ESB Germany (2015-2020); Swiss HBM4EU study (2020); DIET-HBM Iceland (2019-2020); ESTEBAN France (2014-2016)) were included representing Northern and Western Europe. Overall, median values were below the reported quantification limits (LOQs) (0.05-0.1 microg/L). The 95th percentiles (P95) ranged between 0.24 and 0.37 microg/L urine for Gly and between 0.21 and 0.38 microg/L for AMPA. Lower values were observed in adults compared to children. Indications exist for autonomous sources of AMPA in the environment. As for children, reversed dosimetry calculations based on HBM data in adults did not lead to exceedances of the ADI (proposed acceptable daily intake of EFSA for Gly 0.1 mg/kg bw/day based on histopathological findings in the salivary gland of rats) indicating no human health risks in the studied populations at the moment. However, the controversy on carcinogenicity, potential endocrine effects and the absence of a group ADI for Gly and AMPA induce uncertainty to the risk assessment. Exposure determinant analysis showed few significant associations. More data on specific subgroups, such as those occupationally exposed or living close to agricultural fields or with certain consumption patterns (vegetarian, vegan, organic food, high cereal consumer), are needed to evaluate major exposure sources
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