Two-photon absorption in potassium niobate

We report measurements of thermal self-locking of a Fabry-Perot cavity containing a potassium niobate (KNbO3) crystal. We develop a method to determine linear and nonlinear optical absorption coefficients in intracavity crystals by detailed analysis of the transmission lineshapes. These lineshapes are typical of optical bistability in thermally loaded cavities. For our crystal, we determine the one-photon absorption coefficient at 846 nm to be (0.0034 \pm 0.0022) per m and the two-photon absorption coefficient at 846 nm to be (3.2 \pm 0.5) \times 10^{-11} m/W and the one-photon absorption coefficient at 423 nm to be (13 \pm 2) per m. We also address the issue of blue-light-induced-infrared-absorption (BLIIRA), and determine a coefficient for this excited state absorption process. Our method is particularly well suited to bulk absorption measurements where absorption is small compared to scattering. We also report new measurements of the temperature dependence of the index of refraction at 846 nm, and compare to values in the literature.Comment: 8 pages. To appear in J. Opt. Soc. Am.

Oxidation state specific analysis of arsenic species in tissues of wild-type and arsenic (+ 3 oxidation state) methyltransferase-knockout mice

Arsenic methyltransferase (As3mt) catalyzes the conversion of inorganic arsenic (iAs) to its methylated metabolites, including toxic methylarsonite (MAsIII) and dimethylarsinite (DMAsIII). Knockout (KO) of As3mt was shown to reduce the capacity to methylate iAs in mice. However, no data are available on the oxidation states of As species in tissues of these mice. Here, we compare the oxidation states of As species in tissues of male C57BL/6 As3mt-KO and wild-type (WT) mice exposed to arsenite (iAsIII) in drinking water. WT mice were exposed to 50 mg/L As and As3mt-KO mice that cannot tolerate 50 mg/L As were exposed to 0, 15, 20, 25 or 30 mg/L As. iAsIII accounted for 53% to 74% of total As in liver, pancreas, adipose, lung, heart, and kidney of As3mt-KO mice; tri- and pentavalent methylated arsenicals did not exceed 10% of total As. Tissues of WT mice retained iAs and methylated arsenicals: iAsIII, MAsIII and DMAsIII represented 55%–68% of the total As in the liver, pancreas, and brain. High levels of methylated species, particularly MAsIII, were found in the intestine of WT, but not As3mt-KO mice, suggesting that intestinal bacteria are not a major source of methylated As. Blood of WT mice contained significantly higher levels of As than blood of As3mt-KO mice. This study is the first to determine oxidation states of As species in tissues of As3mt-KO mice. Results will help to design studies using WT and As3mt-KO mice to examine the role of iAs methylation in adverse effects of iAs exposure

Blue light effects on rose photosynthesis and photomorphogenesis

Through its impact on photosynthesis and morphogenesis, light is the environmental factor that most affects plant architecture. Using light rather than chemicals to manage plant architecture could reduce the impact on the environment. However, the understanding of how light modulates plant architecture is still poor and further research is needed. To address this question, we examined the development of two rose cultivars, Rosa hybrida‘Radrazz’ and Rosa chinensis‘Old Blush’, cultivated under two light qualities. Plants were grown from one-node cuttings for 6 weeks under white or blue light at equal photosynthetic efficiencies. While plant development was totally inhibited in darkness, blue light could sustain full development from bud burst until flowering. Blue light reduced the net CO2 assimilation rate of fully expanded leaves in both cultivars, despite increasing stomatal conductance and intercellular CO2 concentrations. In ‘Radrazz’, the reduction in CO2 assimilation under blue light was related to a decrease in photosynthetic pigment content, while in both cultivars, the chl a/b ratio increased. Surprisingly, blue light could induce the same organogenetic activity of the shoot apical meristem, growth of the metamers and flower development as white light. The normal development of rose plants under blue light reveals the strong adaptive properties of rose plants to their light environment. It also indicates that photomorphogenetic processes can all be triggered by blue wavelengths and that despite a lower assimilation rate, blue light can provide sufficient energy via photosynthesis to sustain normal growth and development in roses

Thromboembolic risk stratification by TRiP(cast) score to rationalise thromboprophylaxis in patients with lower leg trauma requiring immobilisation: a study protocol of the casting stepped-wedge cluster randomised trial.

Patients with lower limb trauma requiring orthopaedic immobilisation may be at risk of venous thromboembolism but opinions differ about who may benefit from thromboprophylactic anticoagulant treatment.The aim of this CASTING study is to demonstrate the safety of thromboprophylaxis based on the Thrombosis Risk Prediction for patients with cast immobilisation (TRiP(cast) score with regards to the 3-month incidence of symptomatic venous thromboembolism events in low-risk patients not receiving thromboprophylaxis, as well as the usefulness of this strategy on the rate of patients receiving anticoagulant treatment in comparison to current practice. CASTING will be a stepped-wedge cluster randomised controlled clinical trial, performed in 15 emergency departments in France and Belgium. With their informed consent, outpatients admitted to one of the participating emergency departments for a lower limb trauma requiring orthopaedic immobilisation without surgery will be included. All centres will begin the trial with the 'observational period' and, every 2 weeks, 1 centre will be randomly assigned to switch to the 'interventional period' and to apply the TRiP(cast) score, in which only patients with a score ≥7 will receive thromboprophylactic anticoagulant treatment. The primary endpoint is the rate of clinical thromboembolic events within 90 days following the inclusion of low-risk patients not receiving thromboprophylaxis. The protocol has been approved by the Comité de Protection des Personnes Sud I (Ethics Review ID-RCB: 2019-A01829-48) for France and the Comité d'éthique hôpital-facultaire Saint Luc (N° B403201941338) for Belgium. It is carried out in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. The findings of this study will be disseminated in peer-reviewed journals and at scientific conferences. NCT04064489

Methylated trivalent arsenicals are potent inhibitors of glucose stimulated insulin secretion by murine pancreatic islets

Epidemiologic evidence has linked chronic exposure to inorganic arsenic (iAs) with an increased prevalence of diabetes mellitus. Laboratory studies have identified several mechanisms by which iAs can impair glucose homeostasis. We have previously shown that micromolar concentrations of arsenite (iAsIII) or its methylated trivalent metabolites, methylarsonite (MAsIII) and dimethylarsinite (DMAsIII), inhibit the insulin-activated signal transduction pathway, resulting in insulin resistance in adipocytes. Our present study examined effects of the trivalent arsenicals on insulin secretion by intact pancreatic islets isolated from C57BL/6 mice. We found that 48-hour exposures to low subtoxic concentrations of iAsIII, MAsIII or DMAsIII inhibited glucose-stimulated insulin secretion (GSIS), but not basal insulin secretion. MAsIII and DMAsIII were more potent than iAsIII as GSIS inhibitors with estimated IC50≤0.1 μM. The exposures had little or no effects on insulin content of the islets or on insulin expression, suggesting that trivalent arsenicals interfere with mechanisms regulating packaging of the insulin transport vesicles or with translocation of these vesicles to the plasma membrane. Notably, the inhibition of GSIS by iAsIII, MAsIII or DMAsIII could be reversed by a 24-hour incubation of the islets in arsenic-free medium. These results suggest that the insulin producing pancreatic β-cells are among the targets for iAs exposure and that the inhibition of GSIS by low concentrations of the methylated metabolites of iAs may be the key mechanism of iAs-induced diabetes

French political science at a turning point

This paper outlines the origins and institutionalization process of French political science since 1945. It sketches the present state of the discipline, and it analyses recent trends that appear almost as a form of ‘de-institutionalization’. Overall, the discipline is quite well entrenched and is independent in terms of recruitment with its own teaching and research branches. However, political scientists suffer from a relative lack of visibility in the public space in comparison with their colleagues from more prominent disciplines. In many fields French political science remains invisible at the international level, though this may change considerably in the years to come. The main element of uncertainty comes from the ongoing reforms, the redefinition of the partnership between universities, the Instituts d'Etudes Politiques and the CNRS, and the way the autonomy of universities will be implemented

A review of selected indicators of particle, nutrient and metal inputs in coral reef lagoon systems

This review presents environmental and biological indicators of the impact of three major categories of inputs in coral reef lagoons i.e. particles, nutrients and metals. Information was synthesized to extract well established indicators together with some interesting new concepts currently under development, and to provide the reader with an assessment of their respective advantages and drawbacks. The paper has been organized according to the capacity of three categories of indicators to respond either in a specific or a non specific way to a given source of input. The first section focuses on abiotic indicators which main interest is to respond instantaneously and in a truly specific way to a given source of input. The second and third sections present informations on bioindicators either at the sub-individual level or at the individual to community level, indicator specificity generally decreasing as a direct function of biological or ecological complexity. This review showed that even though significant work has already been done on coral reef ecosystems, much more scientific studies are still needed to answer the growing local demands for simple and truly validated tools to be used in environmental surveys. It is further stressed that, due to the biological and environmental diversity of coral reef lagoons, a preliminary step of on-site validation must be considered as an absolute prerequisite when indicators are planned to be used in the frame of a local environmental monitoring programme

Sex-dependent effects of preconception exposure to arsenite on gene transcription in parental germ cells and on transcriptomic profiles and diabetic phenotype of offspring

Chronic exposure to inorganic arsenic (iAs) has been linked to diabetic phenotypes in both humans and mice. However, diabetogenic effects of iAs exposure during specific developmental windows have never been systematically studied. We have previously shown that in mice, combined preconception and in utero exposures to iAs resulted in impaired glucose homeostasis in male offspring. The goal of the present study was to determine if preconception exposure alone can contribute to this outcome. We have examined metabolic phenotypes in male and female offspring from dams and sires that were exposed to iAs in drinking water (0 or 200 μg As/L) for 10 weeks prior to mating. The effects of iAs exposure on gene expression profiles in parental germ cells, and pancreatic islets and livers from offspring were assessed using RNA sequencing. We found that iAs exposure significantly altered transcript levels of genes, including diabetes-related genes, in the sperm of sires. Notably, some of the same gene transcripts and the associated pathways were also altered in the liver of the offspring. The exposure had a more subtle effect on gene expression in maternal oocytes and in pancreatic islets of the offspring. In female offspring, the preconception exposure was associated with increased adiposity, but lower blood glucose after fasting and after glucose challenge. HOMA-IR, the indicator of insulin resistance, was also lower. In contrast, the preconception exposure had no effects on blood glucose measures in male offspring. However, males from parents exposed to iAs had higher plasma insulin after glucose challenge and higher insulinogenic index than control offspring, indicating a greater requirement for insulin to maintain glucose homeostasis. Our results suggest that preconception exposure may contribute to the development of diabetic phenotype in male offspring, possibly mediated through germ cell-associated inheritance. Future research can investigate role of epigenetics in this phenomenon. The paradoxical outcomes in female offspring, suggesting a protective effect of the preconception exposure, warrant further investigation

Development of a PbWO4 Detector for Single-Shot Positron Annihilation Lifetime Spectroscopy at the GBAR Experiment

We have developed a PbWO4 (PWO) detector with a large dynamic range to measure the intensity of a positron beam and the absolute density of the ortho-positronium (o-Ps) cloud it creates. A simulation study shows that a setup based on such detectors may be used to determine the angular distribution of the emission and reflection of o-Ps to reduce part of the uncertainties of the measurement. These will allow to improve the precision in the measurement of the cross-section for the (anti)hydrogen formation by (anti)proton-positronium charge exchange and to optimize the yield of antihydrogen ion which is an essential parameter in the GBAR experiment

Adventive hydrothermal circulation on Stromboli volcano (Aeolian Islands, Italy) revealed by geophysical and geochemical approaches: Implications for general fluid flow models on volcanoes

International audienceOn March 15th 2007 a paroxysmal explosion occurred at the Stromboli volcano. This event generated a large amount of products, mostly lithic blocks, some of which impacted the ground as far as down to 200 m a.s.l., about 1.5 km far away from the active vents. Two days after the explosion, a new vapour emission was discovered on the north-eastern flank of the volcanic edifice, at 560 m a.s.l., just above the area called "Nel Cannestrà". This new vapour emission was due to a block impact. In order to investigate the block impact area to understand the appearance of the vapour emission, we conducted on May 2008 a multidisciplinary study involving Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), Self-Potential (SP), CO2 soil diffuse degassing and soil temperature surveys. This complementary data set revealed the presence of an anomalous conductive body, probably related to a shallow hydrothermal level, at about 10-15 m depth, more or less parallel to the topography. It is the first time that such a hydrothermal fluid flow, with a temperature close to the water boiling point (76 °C) has been evidenced at Stromboli at this low elevation on the flank of the edifice. The ERT results suggest a possible link between (1) the main central hydrothermal system of Stromboli, located just above the plumbing system feeding the active vents, with a maximum of subsurface soil temperature close to 90 °C and limited by the NeoStromboli summit crater boundary and (2) the investigated area of Nel Cannestrà, at ~ 500 m a.s.l., a buried eruptive fissure active 9 ka ago. In parallel, SP and CO2 soil diffuse degassing measurements suggest in this sector at slightly lower elevation from the block impact crater a magmatic and hydrothermal fluid rising system along the N41° regional fault. A complementary ERT profile, on May 2009, carried out from the NeoStromboli crater boundary down to the block impact crater displayed a flank fluid flow apparently connected to a deeper system. The concept of shallow hydrothermal level have been compared to similar ERT results recently obtained on Mount Etna and La Fossa cone of Vulcano. This information needs to be taken into account in general fluid flow models on volcanoes. In particular, peripheral thermal waters (as those bordering the north-eastern coast of Stromboli) could be contaminated by hydrothermal and magmatic fluids coming from regional faults but also from the summit