Operating characteristics of a prototype high energy gamma-ray telescope

The field of gamma-ray astronomy in the energy range from ten to several hundred MeV is severely limited by the angular resolution that can be achieved by present instruments. The identification of some of the point sources found by the COS-B mission and the resolution of detailed structure existing in those sources may depend on the development of a new class of instrument. The coded aperture mask telescope, used successfully at X-ray energies hold the promise of being such an instrument. A prototype coded aperture telescope was operated in a tagged photon beam ranging in energy from 23 to 123 MeV. The purpose of the experiment was to demonstrate the feasibility of operating a coded aperture mask telescope in this energy region. Some preliminary results and conclusions drawn from some of the data resulting from this experiment are presented

Secondary gamma-ray production in a coded aperture mask

The application of the coded aperture mask to high energy gamma-ray astronomy will provide the capability of locating a cosmic gamma-ray point source with a precision of a few arc-minutes above 20 MeV. Recent tests using a mask in conjunction with drift chamber detectors have shown that the expected point spread function is achieved over an acceptance cone of 25 deg. A telescope employing this technique differs from a conventional telescope only in that the presence of the mask modifies the radiation field in the vicinity of the detection plane. In addition to reducing the primary photon flux incident on the detector by absorption in the mask elements, the mask will also be a secondary radiator of gamma-rays. The various background components in a CAMTRAC (Coded Aperture Mask Track Chamber) telescope are considered. Monte-Carlo calculations are compared with recent measurements obtained using a prototype instrument in a tagged photon beam line

Association of follow-up infarct volume with functional outcome in acute ischemic stroke: a pooled analysis of seven randomized trials.

BACKGROUND: Follow-up infarct volume (FIV) has been recommended as an early indicator of treatment efficacy in patients with acute ischemic stroke. Questions remain about the optimal imaging approach for FIV measurement. OBJECTIVE: To examine the association of FIV with 90-day modified Rankin Scale (mRS) score and investigate its dependency on acquisition time and modality. METHODS: Data of seven trials were pooled. FIV was assessed on follow-up (12 hours to 2 weeks) CT or MRI. Infarct location was defined as laterality and involvement of the Alberta Stroke Program Early CT Score regions. Relative quality and strength of multivariable regression models of the association between FIV and functional outcome were assessed. Dependency of imaging modality and acquisition time (≤48 hours vs >48 hours) was evaluated. RESULTS: Of 1665 included patients, 83% were imaged with CT. Median FIV was 41 mL (IQR 14-120). A large FIV was associated with worse functional outcome (OR=0.88(95% CI 0.87 to 0.89) per 10 mL) in adjusted analysis. A model including FIV, location, and hemorrhage type best predicted mRS score. FIV of ≥133 mL was highly specific for unfavorable outcome. FIV was equally strongly associated with mRS score for assessment on CT and MRI, even though large differences in volume were present (48 mL (IQR 15-131) vs 22 mL (IQR 8-71), respectively). Associations of both early and late FIV assessments with outcome were similar in strength (ρ=0.60(95% CI 0.56 to 0.64) and ρ=0.55(95% CI 0.50 to 0.60), respectively). CONCLUSIONS: In patients with an acute ischemic stroke due to a proximal intracranial occlusion of the anterior circulation, FIV is a strong independent predictor of functional outcome and can be assessed before 48 hours, oneither CT or MRI

Effects of Statins to Reduce All-Cause Mortality in Heart Failure Patients: Findings from the EPICAL2 Cohort Study.

The addition of statins to standard care in heart failure (HF) patients remains controversial in clinical practice. Large-scale clinical trials failed to show mortality benefits, but uncertainty persists in real-world settings. We evaluated whether the prescription of statins at hospital discharge is associated with a reduction in all-cause mortality at up to 1 year of follow-up in HF patients. We analyzed data from Epidémiologie et Pronostic de l'Insuffisance Cardiaque Aiguë en Lorraine (EPICAL2) cohort study of 2254 hospitalized acute HF patients who were admitted to 21 hospitals located in northeast France for acute HF between October 2011 and October 2012 and who received statins at discharge compared with patients who did not. We used propensity score matching and instrumental variable analyses to estimate the treatment effects of statins, and a multivariable Cox proportional-hazards model to examine survival with statin use, adjusting for patient demographics, HF characteristics, medical history, comorbidities, drug treatment and other known potential confounders. We plotted Kaplan-Meier survivor curves, and used log-rank test to determine the equality of survivor functions. We included 2032 patients in this investigation: 919 (45%) in the statin-treated group and 1113 (55%) in the control group. The estimated average statin-treatment effects for all-cause mortality in HF failed to demonstrate a significant effect on mortality [Z = - 1.73, 95% confidence interval (CI) - 0.11 to 0.007, p value = 0.083, and Z = - 0.95, 95% CI - 1.34 to 0.46, p value = 0.34] for propensity score matching and instrumental variable analyses, respectively. Moreover, the Cox proportional-hazards model showed that statin prescription was not significantly associated with the rate of death (hazard ratio = 0.85, 95% CI 0.66-1.11, p value = 0.26), adjusted for all confounders. In patients with HF (and reduced or preserved ejection fraction), the prescription of statins did not appear to be associated with better survival after 1 year of follow-up in the EPICAL2 cohort. We cannot exclude that a subpopulation of HF patients may have some benefits compared with the whole HF population or that there might be a lack of power to show such effect. NCT02880358

Water chemistry and isotopic characteristics to monitor fluid-rock interactions, during a small scale CO_2 injection

In order to investigate the extent of in-situ CO2-fluid-rock reactions relevant to the effectiveness of CO2 sequestration two single well push-pull tests were performed in a basaltic rock aquifer at the Lamont-Doherty Earth Observatory test well site, New York: - Blank test: a non reactive test, without CO2 equilibration of the injection fluid, - CO2 test: a reactive test, with CO2 equilibration (CO2 pressure ≈ 1 bar) of the injection fluid. For both tests, conservative chemical and isotopic tracers (NaCl, D, 18O) were added to the injection fluid, in order to evaluate mixing between the injected water and the background water in the aquifer. The injection interval, located at the contact zone between the chilled dolerite and the underlying metamorphosed sedimentary rocks, was hydraulically isolated with a straddle packer system. For the blank test, post-injection chemical and isotopic characteristics of retrieved water samples (major ions, DIC, δ13CDIC) remain unchanged, confirming the non reactivity of the system (in the absence of CO2). For the CO2 test, the variations of these characteristics underline the reactivity of the CO2 in the aquifer and allow to identify reactions of the dissolved CO2 with the surrounding rocks, mainly the dissolution of carbonate minerals. Results provided by the CO2 test show that, within the context of this study (incubation period of 3 weeks, injection fluid equilibrated with CO2 pressure of 1 bar); the CO2 reacted with the rock minerals to form carbon-bearing ionic species (HCO3-). Thus ionic trapping was the main trapping mechanism

Water–rock interactions during a CO2 injection field-test: implications on host rock dissolution and alteration effects

We investigated the nature and rates of in-situ CO2–fluid–rock reactions during an aqueous phase CO2 injection test. Two push–pull test experiments were performed at the Lamont–Doherty Earth Observatory test site (New York, USA): a non reactive control test without CO2 addition and a reactive test with CO2 equilibrated with the injected solution at a partial pressure of 1.105 Pa. The injected solution contained chemical and isotopic conservative tracers (NaCl and 18O) and was injected in an isolated and permeable interval at approximately 250 m depth. The injection interval was located at the contact zone between the Palisades sill (chilled dolerite) and the underlying metamorphic Newark Basin sediments and the injected solution incubated within this interval for roughly 3 weeks. Physico-chemical parameters were measured on the surface (pH, temperature, electrical conductivity) and water samples were collected for chemical (Dissolved Inorganic Carbon — DIC, major ions) as well as for isotopic (?13CDIC, ?18O) analyses.For the control test, post-injection chemical and isotopic compositions of recovered water samples display mixing between the background water and the injected solution. For the reactive CO2 test, observed ?13CDIC and DIC both increase, and enrichment in Ca2+, Mg2+, K+ allow for quantification of the chemical pathways through which aqueous CO2 and subsequent H2CO3 were converted into HCO3?. Dissolution of carbonate minerals was the dominant H2CO3 neutralization process (? 52 ± 7%), followed by cation exchange and/or dissolution of silicate minerals (? 45 ± 10%, for both processes), and to a minor extent, mixing of the injected solution with the formation water (? 3 ± 1%). The results confirm the rapid dissolution kinetics of carbonate minerals compared to those of basic silicate minerals. However, our results remain marked by uncertainties due to the natural variability of the background water composition, in mass balance calculations. These experiments imply that the use of accurate DIC measurements can quantify the relative contribution of CO2–fluid–rock reactions and evaluate the geochemical trapping potential for CO2 storage in reactive reservoir environments

Pharmacoepidemiol Drug Saf

PURPOSE: The purpose of the study is to describe the trajectories of oral medication prescriptions in patients with heart failure with reduced ejection fraction (HFrEF) over 3 years after discharge from hospitalization for heart failure. We then evaluated the adherence of these prescriptions to the European Society of Cardiology (ESC) guideline-recommended medications and identified patient characteristics associated with nonadherence. METHODS: We used data from the EPICAL2 cohort study. HFrEF patients who had completed prescriptions at discharge and at 6-month follow-up were included and followed for 36 months. The following medication agents were considered adherent to guidelines: renin-angiotensin system (RAS) blockers [angiotensin-converting enzyme inhibitor (ACEI) or an angiotensin-receptor blocker (ARB)] plus a beta-blocker (BB) or RAS blocker plus BB plus mineralocorticoid receptor antagonists (MRAs). The evolution of drug prescriptions and the adherence to ESC guidelines were assessed by using sequence analysis and clustering approaches. Patient characteristics associated with nonadherence were identified by logistic regression analyses. RESULTS: A typology of four therapeutic clusters was obtained, among which two clusters were adherent to recommendations and two were not. The adherent clusters consisted of bitherapy (RAS blockers-BB) and tritherapy (RAS blockers-BB-MRA) for about 64% of patients and remain stable over time. The nonadherent clusters consisted of nonprescription of BB for about 22% of patients or nonprescription of RAS blocker for about 14%. The main reason for nonprescription of BB was a concomitant obstructive airway disease (asthma or COPD) but was a concomitant chronic kidney disease for nonprescription of RAS blocker. CONCLUSION: Adherence to guideline-recommended medications while being hospitalized is of great importance because prescriptions are quite stable over time after discharge. HFrEF patients are most often older, with various comorbidities, such as chronic kidney disease or asthma/COPD, which importantly limit physicians' ability to prescribe recommended drugs, leading to suboptimal adherence to guidelines

General practitioners' perceptions of vaccination controversies: a French nationwide cross-sectional study

International audienceObjectives: We aimed to study general practitioners' (GPs') perceptions of vaccines that have been a subject of controversy in France. Methods: A cross-sectional survey in 2014 asked a representative national sample of GPs, randomly selected from the exhaustive database of health professionals in France, about their perceptions of the likelihood of serious adverse events potentially associated with six different vaccines: for two of them the association was based on some scientific evidence, whereas for the other four this is not the case. We performed a cluster analysis to construct a typology of GPs' perceptions about the likelihood of these potential six associations. Factors associated with certain clusters of interest were identified using logistic regression models. Results: Overall, 1582 GPs participated in the questionnaire survey (1582/1712 GPs who agreed to participate, 92%). Cluster analysis identified four groups of GPs according to their susceptibility to vaccine controversies: 1) limited susceptibility to controversies (52%); 2) overall unsure, but rejected the association between hepatitis B vaccine and multiple sclerosis (32%); 3) highly susceptible to controversies (11%); and 4) unsure (5%). We found that GPs who occasionally practised alternative medicine (OR 2.71, 95% CI 1.65-4.45), and those who considered information provided by mass media as reliable (OR 2.04, 95% CI 1.65-3.99) were more susceptible to controversies. Conclusions: GPs had different profiles of susceptibility to vaccination controversies, and most of their perceptions of these controversies were not based on scientific evidence

CO2 ionic trapping at meta-sedimentary aquifer, following a CO2 injection push-pull test

In order to study CO2-water-rock reactions relative to effectiveness of CO2 geological storage, small-scale CO2 injection experiments were performed, as single well push-pull tests, at the Lamont Doherty Earth Observatory test well site (New-York, USA). The injection interval was located at the contact zone between the chilled dolerite and the underlying metamorphosed sedimentary rocks. The variations of post-injection chemical and isotopic characteristics of retrieved water samples (major ions, DIC, 13CDIC) underline the CO2 reactivity in the aquifer and allow to identify reactions of the dissolved CO2 with the surrounding rocks, mainly the dissolution of carbonate minerals and complementary cation exchange

Pyrohydrolysis-IRMS determination of silicate chlorine stable isotope compositions. Application to oceanic crust and meteorite samples

This contribution describes the optimization of chlorine extraction from silicate samples by pyrohydrolysis prior to the precise determination of Cl stable-isotope compositions (637 Cl) by gas source, dual inlet Isotope Ratio Mass Spectrometry (IRMS) on CH(3)Clg. The complete method was checked on three international reference materials for Cl-content and two laboratory glass standards. Whole procedure blanks are lower than 0. 5 mu mol, corresponding to less than 10 wt.% of most of the sample chloride analysed. In the absence of international chlorine isotope rock, we report here Cl extracted compared to accepted Cl contents and reproducibilities on Cl and delta Cl-37 measurements for the standard rocks. After extraction, the Cl contents of the three international references compared within error with the accepted values (mean yield = 94 +/-10%) with reproducibilities better than 12% (10). The laboratory glass standards - andesite SO100DS92 and phonolite S9(2) - were used specifically to test the effect of chloride amount on the measurements. They gave Cl extraction yields of 100 +/-6% (1 sigma-; n = 15) and 105 +/- 8% (1 sigma-; n = 7), respectively, with delta Cl-37 values of -0.51 0.14%o and -0.39 0.17%o (1g). In summary, for silicate samples with Cl contents between 39 and 9042 ppm, the Pyrohydrolysis/HPLC method leads to overall CI extraction yields of 100 8%, reproducibilities on Cl contents of 7% and on delta Cl-37 measurements of 0.12%o (all 1 sigma). The method was further applied to ten silicate rocks of various mineralogy and chemistry (meteorite, fresh MORB glasses, altered basalts and setpentinized peridotites) chosen for their large range of Cl contents (70-2156 ppm) and their geological significance. delta Cl-37 values range between -2.33 and -0.50%o. These strictly negative values contrast with the large range and mainly positive values previously reported for comparable silicate samples and shown here to be affected by analytical problems. Thus we propose a preliminary, revised terrestrial CI cycle, mainly dominated by negative and zero delta Cl-37 values. (C) 2007 Elsevier B.V. All rights reserved