Solid-to-plasma transition of polystyrene induced by a nanosecond laser pulse within the context of inertial confinement fusion.

Laser direct drive (LDD) inertial confinement fusion (ICF) involves irradiating a spherical target of thermonuclear fuel coated with an ablator, usually made of polystyrene. Laser energy absorption near the target surface leads to matter ablation, hydrodynamic shocks, and ultimately capsule implosion. The conservation of spherical symmetry is crucial for implosion efficiency, yet spatial modulations in laser intensity can induce nonuniformities, causing the laser imprint phenomenon. Understanding laser imprint, especially considering the initial solid state, is essential for advancing LDD ICF. A first microscopic model of solid-to-plasma transition was built in 2019, accounting for laser absorption in the solid state with a band-structure-based ionization model. This model has been improved to include chemical fragmentation and a more accurate description of electron collision frequency in various matter states. The latest development involves assessing the model's reliability by comparing theoretical predictions with experimental observations. Despite the success of this approach, questions remain, leading to further investigations and observations under different irradiation conditions. This work presents an experiment with a nanosecond pulse, taking into account hydrodynamic effects, and measures transmission dynamics over the entire laser beam area to observe two-dimensional effects. The objective is to adapt the theoretical model, couple it with a hydrodynamic code, and observe additional effects related to the initial solid state.

Counterfactually mediated emotions: a developmental study of regret and relief in a probabilistic gambling task.

Regret and relief are related to counterfactual thinking and rely on comparison processes between what has been and what might have been. In this article, we study the development of regret and relief from late childhood to adulthood (11.2-20.2 years), and we examine how these two emotions affect individuals' willingness to retrospectively reconsider their choice in a computerized monetary gambling task. We asked participants to choose between two "wheels of fortune" that differed in the amount of gain and loss expected and the probability of winning. We manipulated the outcome of the wheel of fortune that was not selected by participants to induce regret or relief. For each trial, participants rated how they felt about the outcome and their willingness to modify their choice. Participants' ratings suggest that regret and relief are stronger in adults than in children and adolescents. Regret affects participants' willingness to modify their initial choice, but this desire is stronger for adults than for children. In children, the experience of regret seems to be dissociated from the willingness to reconsider a choice. This study provides the first evidence that the ability to experience counterfactually mediated emotions, such as regret and relief, and the ability to take them into consideration continue to develop during late childhood and adolescence.

[The role of written action plans in the management of asthma]. / Apports du plan d'action écrit dans la prise en charge de l'asthme.

The Written Action Plan is a tool designed to help people with asthma to manage their condition when they experience an exacerbation. Asthma guidelines are consistent in their recommendation that action plans are useful for all people with asthma, but implementation is not systematic. The evidence base for such plans is limited because of methodological biases, but does support their effectiveness. The recommended action plan involves different color-coded zones which advise patients to adjust their management, such as increasing the level of daily treatment, or introducing oral corticosteroids based on symptoms and peak expiratory flow measurements. Recommendations are much less clear as to how to encourage patients to adopt and take ownership of their plan, although they all recommend that written action plans be incorporated into therapeutic education programs. The published literature shows that those caring for people with asthma may not support action plans because they are uncomfortable with the necessary educational posture and as a consequence of this they are under-utilized by patients. Patient-centered therapeutic education principles help us understand both how to encourage the patient want to have a written action plan and how to co-create it with them so that it is useful and meaningful in their life in order to make it more than just a disconnected tool.

Improved modeling of the solid-to-plasma transition of polystyrene ablator for laser direct-drive inertial confinement fusion hydrocodes.

The target performance of laser direct-drive inertial confinement fusion (ICF) can be limited by the development of hydrodynamic instabilities resulting from the nonhomegeneous laser absorption at the target surface, i.e., the laser imprint on the ablator. To understand and describe the formation of these instabilities, the early ablator evolution during the laser irradiation should be considered. In this work, an improved modeling of the solid-to-plasma transition of a polystyrene ablator for laser direct-drive ICF is proposed. This model is devoted to be implemented in hydrocodes dedicated to ICF which generally assume an initial plasma state. The present approach consists of the two-temperature model coupled to the electron, ion and neutral dynamics including the chemical fragmentation of polystyrene. The solid-to-plasma transition is shown to significantly influence the temporal evolution of both free electron density and temperatures, which can lead to different shock formation and propagation compared with an initial plasma state. The influence of the solid-to-plasma transition on the shock dynamics is evidenced by considering the scaling law of the pressure with respect to the laser intensity. The ablator transition is shown to modify the scaling law exponent compared with an initial plasma state.

Intubation decision criteria in adult epiglottitis.

OBJECTIVES: To identify contributive criteria in decision-making for intubation in acute epiglottitis, based on clinical and endoscopic data in adult patients, and to study clinical and biological characteristics and management. MATERIALS AND METHODS: Diagnosis was established by flexible endoscopy showing epiglottic edema in association with general signs of sepsis in 28 patients consulting into two French hospitals between 2005 and 2016. Retrospective univariate and multivariate analysis between patients managed by intubation (Group I) or surveillance (Group S) was performed on clinical and endoscopic data. RESULTS: Ten patients were intubated (36%). On univariate analysis, 4 variables were suggestively associated with intubation. On multivariate analysis, associations remained suggestive for dyspnea (OR=50.6; 95% CI=[2.7; 940.1]) and supraglottic edema extension (OR=42.2; 95% CI=[2.2; 799.5]). The area under the curve identifying intubated patients on these 2 criteria was 90.8%, testifying to high discrimination. CONCLUSION: Intubation must always be considered in epiglottitis. Dyspnea and supraglottic extension of the edema seem to be the two main criteria to be considered in airway control decision-making.

Immediate activation after cochlear implantation: Preliminary Study.

OBJECTIVE: To assess the feasibility of immediate activation of cochlear implants. MATERIAL AND METHODS: A retrospective study compared speech audiometry results at 6 months post-implantation, implant fitting data and complications, on Student test, between 19 patients receiving day-1 implant activation (immediate activation: IA) and 10 patients with activation at 2 weeks (classical activation: CA). RESULTS: Mean speech comprehension, using Fournier bisyllabic word lists at 60dB 6 months after implantation, was 61.58% in IA and 71% in CA (P>0.05). Mean intelligibility thresholds for 50% word-recognition were respectively 39.74dB and 36.5dB (P>0.05). Speech audiometry results at 6 months were not affected by immediate versus classical activation. Comfort-level settings at 1 month in IA were not significantly different (Student test: P>005) from intraoperative neural response thresholds: i.e., were practically stable. One IA patient required delayed activation at 1 month because of hematoma interfering between the external and internal parts of the implant. There were no other complications. The mean number of fitting sessions during the first year was 6.05 in the IA group and 6.55 in the CA group (P>0.05). CONCLUSION: Given certain precautions during follow-up, immediate activation after cochlear implantation was feasible, and did not impair audiometric results.

Modeling the solid-to-plasma transition for laser imprinting in direct-drive inertial confinement fusion.

Laser imprinting possesses a potential danger for low-adiabat and high-convergence implosions in direct-drive inertial confinement fusion (ICF). Within certain direct-drive ICF schemes, a laser picket (prepulse) is used to condition the target to increase the interaction efficiency with the main pulse. Whereas initially the target is in a solid state (of ablators such as polystyrene) with specific electronic and optical properties, the current state-of-the-art hydrocodes assume an initial plasma state, which ignores the detailed plasma formation process. To overcome this strong assumption, a model describing the solid-to-plasma transition, eventually aiming at being implemented in hydrocodes, is developed. It describes the evolution of main physical quantities of interest, including the free electron density, collision frequency, absorbed laser energy, temperatures, and pressure, during the first stage of the laser-matter interaction. The results show that a time about 100 ps is required for the matter to undergo the phase transition, the initial solid state thus having a notable impact on the subsequent plasma dynamics. The nonlinear absorption processes (associated to the solid state) are also shown to have an influence on the thermodynamic quantities after the phase transition, leading to target deformations depending on the initial solid state. The negative consequences for the ICF schemes consist in shearing of the ablator and possibly preliminary heating of the deuterium-tritium fuel.

Low serum selenium concentrations in French patients with measles.

OBJECTIVE: Selenium deficiency adversely affects the clinical outcome of measles in the tropics. In developed countries, serum selenium level has never been investigated during acute measles. The aim of this study was to determine serum selenium concentrations in French patients with acute measles and to seek correlations with clinical and virological findings. PATIENTS AND METHODS: We studied serum selenium concentrations in 94 French patients with acute measles and in 99 healthy controls matched for age and sex. RESULTS: The mean of selenium concentration was significantly lower in the patients than in the controls (46.4±14.1µg/L versus 86.5±13.9µg/L, P<0.0001). In the patients, selenium concentrations were not associated with age, sex, vaccination status, clinical signs or specific antibody responses. Selenium levels did not differ significantly between patients with uncomplicated measles (45.8±14.2µg/L) and patients with complications (52.7±13.2µg/L) (P=0.15). CONCLUSION: Acute measles is associated with significant reduction of selenium level that did not seem to negatively affect the course of the disease suggesting compensating mechanisms in patients from developed countries against the disease.

Implicit identification of irrelevant local objects interacts with global/local processing of hierarchical stimuli.

This work aimed at studying interactions between automatic object identification and global/local perceptual processing. We designed a paradigm in which participants were presented with pairs of hierarchically organized items, composed of global forms made up of local forms. Both global and local forms could represent either objects or non-objects. Subjects were instructed to detect whether the two hierarchical items composing a pair were identical or different. In a dissimilar pair, items differed at one level (target level), the other level, made of similar forms on both sides, was irrelevant to perform the task. We hypothesized that the automatic identification of object could affect the global precedence principle defined by Navon. In agreement with our hypothesis, we found that when the irrelevant level was made of objects, the global precedence effect was reversed. In contrast, the irrelevant level had no effect when the target level included only objects, or when the irrelevant level was made of non-object, the global precedence principle was being preserved in these cases. This interaction is compatible with the existence of two distinct processes working in parallel, namely automatic identification and structural analysis, that could either interfere or act together for the detection of differences.

An evaluation of the biological significance of aluminium in plasma and hair of patients on long-term hemodialysis.

In hemodialyzed patients, the risk of toxicity attributed to the body accumulation of aluminium (Al) justifies the need for monitoring Al in various human media. In this study, Al concentrations in the hair and plasma of 78 hemodialyzed patients with chronic renal failure and of 351 healthy volunteers were measured by electrothermal atomic absorption spectrometry with Zeeman effect. Plasma Al concentrations in patients were significantly higher than in the controls and positively correlated with time on dialysis. Hair Al levels were widely distributed with no significant distinction between patients and controls. On the subject of establishing correlation, the authors stress the importance of taking into account the kinetics of the elimination of minerals from hair. Even when this was done, in the patient group there was no statistical link between plasma and hair Al levels. Hair Al analysis is of no value as an indicator of body Al accumulation.

Congenital hypomagnesemia: alternatives to tissue biopsies for monitoring body magnesium status.

We have been monitoring a 12-year-old boy (his present age) suffering from selective magnesium (Mg) malabsorption. After ascertaining his Mg status, we attempted to maintain Mg balance through the use of oral supplements. Plasma and erythrocyte Mg concentrations were monitored at bimonthly intervals. However these measurements did not accurately reflect Mg status and we subsequently measured Mg in the following tissues: lymphocyte, tooth, and hair. Levels of Mg in stable tissues such as temporary teeth and lymphocytes, unfailingly revealed a marked deficit in Mg that was only two-thirds of the normal levels found in the control group. The use of these readily-accessible stable tissues can thus obviate the need for muscle or bone biopsy. Unfortunately the level in hair is higher than in healthy subjects, and thus does not constitute an adequate measure of Mg status.

Minerals, trace elements and related biological variables in athletes and during physical activity.

This review concerns various minerals (sodium, potassium, calcium, magnesium, phosphorus), trace elements (zinc, manganese, selenium, copper, iron, cobalt, iodine, chromium, fluorine, lead, cadmium) and other biological variables (nitric oxide, L-carnitine, glutamine, serum transferrin receptor, biopyrrins) in relation to hemorheologic effects, stress, immune response and infections during physical and sports activities. In athletes, macroelements in the ionized form contribute to heart and muscle contractions, oxidative phosphorylation and the synthesis and activation of enzymatic systems. Zinc (Zn) protects against the effects of increased free reactive oxygen species such as copper (Cu) and manganese (Mn) (Cu-Zn superoxide dismutases; Mn superoxide dismutase). Selenium in glutathione peroxidase protects the cardiovascular system and the muscles, and helps combat allergic and inflammatory diseases. Copper and iron are involved in many aspects of energy metabolism and are important components in the synthesis of hemoglobin, myoglobin and cytochromes. Fluorine and Cu protect the ligaments and tendons. Physical activity appears to be beneficial to urban residents who are exposed to metal pollution (lead, cadmium). The data cited in this review are often contradictory and incomplete. It is still unclear in many cases how minerals are involved in physiological changes, and much work remains.

Role of aluminium in skin reactions after diphtheria-tetanus-pertussis-poliomyelitis vaccination: an experimental study in rabbits.

The occurrence of subcutaneous nodules at the injection site is one of the complications of diphtheria-tetanus-pertussis-poliomyelitis vaccination, but the causes and mechanisms involved are still poorly understood. An experimental study in the New Zealand rabbit enabled us to determine the frequency of occurrence of these nodules, how long they persist and the histopathologic features of the cells involved. Aluminium (Al) assays by electrothermal atomic absorption spectrometry allowed us to study concentrations both in nodules and the organism (serum, normal skin). The results show an absence of Al diffusion outside nodules, a correlation between infiltrate intensity and Al concentration in nodules and modifications in the histological constituents of nodule cells. The histological picture indicates a foreign body reaction to Al. All these data underscore the role of Al in the formation of early postvaccinal nodules at the injection site.

Biological levels of aluminium after use of aluminium-containing bone cement in post-otoneurosurgery.

Use aluminium-containing biomaterials in otoneurosurgery for reconstitution of bone in contact with cerebrospinal fluid (CSF) also led to cases of encephalopathy and death. We report aluminium (Al) concentrations in the biological fluids of six French patients following use of Al-containing bone cement in otoneurosurgery. In five patients, the mean plasma Al levels (microgram/L) were: 1.20 +/- 0.05 (case 2), 9.20 +/- 0.10 (case 3), 1.00 +/- 0.05 (case 4), 2.80 +/- 0.05 (case 5) and 2.00 +/- 0.05 (case 6). In case 1, Al concentrations were 176 micrograms/L in the postauricular CSF accumulation, 34 micrograms/L in the pontocerebellar angle and 4 and 6 micrograms/L in the lumbar shunt. As a precautionary measure, in the first three cases the biomaterial was removed soon after the intervention, and no increase in plasma or CSF Al was observed. In the other cases, absence of neurobiological symptoms and normal concentrations of Al in plasma led neurosurgeons not to extract this biomaterial. Al assay thus may be considered to be a complementary and at times a decision-generating factor. Care is needed at all stages from sampling through analysis because Al is ubiquitous and factually high results may be clinically misleading. Herein, such considerations are discussed in conjunction with the neurotoxicity of this metal in man. In addition, the authors call for in-depth preliminary trials of these biomaterials in animals prior to introduction on the market.

Toxic and essential trace metals in muscle, liver and kidney of bovines from a polluted area of Morocco.

Toxic and essential trace metals were measured in muscle, bone, liver and kidney of bovine grazing on the municipal wastewater spreading field of Marrakech City (Morocco). Bovines were found to be seriously contaminated by toxic metals, for metal bioaccumulation. The high cadmium content seemed to contribute to a reduction in zinc and copper levels. The arithmetic mean concentrations of zinc, especially cadmium, and levels were higher in liver and kidney, specific target organs copper and cadmium in liver and kidney, were respectively: 126, 112 and 5.1 microg/g in liver; 89, 33 and 10.3 microg/g in kidney.

Trace elements in children's hair, as related exposure in wastewater spreading field of Marrakesh (Morocco).

Lead and cadmium concentration was determined in the hair of 327 school children living in a wastewater spreading field of Marrakesh (Morocco). The influence of age, sex, food habits and family occupation on the children's hair Pb and Cd concentration was also evaluated. Girls had more metal in their hair than boys (16.5 +/- 5.4 micrograms/g and 12.5 +/- 3.5 micrograms/g, respectively). However, for Cd the boys had more metal (2.9 +/- 0.6 and 2.2 +/- 0.4, respectively) but the difference was not statistically significant and metal levels decreased with age. Family occupation, direct contact with wastewater, customs and food habits were the most significant factors influencing the metal content of children's hair. The average Pb and Cd content were higher in the exposed children (14.8 +/- 4.5 micrograms/g and 2.5 +/- 0.5 micrograms/g, respectively) than in the non-exposed children (4.6 +/- 2.2 micrograms/g and 0.6 +/- 0.2, respectively), but the difference was not statistically significant. This study shows that in this area all the population (especially children) was extremely exposed to the danger caused by potentially toxic metals.

Determination of total mercury in human hair samples by cold vapor atomic absorption spectrometry.

A procedure for the determination of mercury in human hair by cold-vapor atomic absorption spectrometry with a new reaction vessel was developed and evaluated. To eliminate the so-called matrix effect, calibration was carried out in an isomedium under identical operating conditions. Under these conditions, the recovery percentage of mercury from human hair digest samples using the peak height method, was 102 +/- 2.2%. The method has been used for measuring the mercury level in hair of different groups of people living in the Nantes, France area.

A study of chromium in human cataractous lenses and whole blood of diabetics, senile, and normal population.

Chromium (Cr) is of known biological importance, necessary for the maintenance of normal glucose metabolism. There is a lower level of blood Cr concentrations in cases of diabetes. Diabetes carries a risk of cataract development, so the potential effects of Cr on the eye may need to be studied in more depth. The presence of this trace element in both normal and cataractous human lenses has to our knowledge not been investigated so far. The concentration of total Cr in 61 human lenses and 38 blood samples was determined by electrothermal atomic absorption spectrometry with Zeeman effect (EAASZ). Analysis of the levels of Cr in human lenses shows a significant difference between normal and diabetic populations, and an absence of difference between senile and diabetic populations.

Total chromium in the human lens. Determination with Zeeman electrothermal atomic absorption spectrometry following mineralization in a mini-autoclave.

A simple, quick procedure has been developed for preparation of human lenses for total chromium (Cr) analysis by electrothermal atomic absorption spectrometry (EAAS). This procedure involves wet ashing in a mini-autoclave with HNO3 and H2SO4. Recovery was 101.6%. This procedure is simple to carry out, does not generate corrosive fumes, and minimizes contaminations. Measurements obtained by this method give values similar to those found previously by more cumbersome methods. It can be conveniently used to prepare biological samples for ultratrace analysis. The mean Cr concentration in human lenses varied between 0.345 +/- 0.147 micrograms/g dry wt in the normal population and 0.205 +/- 0.160 micrograms/g dry wt in cataractous lenses.

French external quality assessment schemes for lead in blood and aluminum in plasma and dialysis water.

An external quality assessment scheme (EQAS) for lead in blood was established in France in 1992 at the request of the Ministry of Labour and organised by the Drug Bureau. Participation is mandatory for laboratories wishing to obtain ministerial approval for the determination of blood lead levels. In 1994, two interlaboratory comparative exercises were carried out, each involving the analysis of 3 samples of human blood (2 with and 1 without lead supplementation). Out of 66 enrolled laboratories, 58 and 60 participated in the two exercises, respectively. The scattering of results was quite comparable to that observed in other EQAS. The EQAS for plasma aluminium was established in 1983 at the request of the Commission on Trace Elements of the Société Française de Biologie Clinique. Today, 80 laboratories in 22 countries on 4 continents participate in this scheme. Six exercises are carried out each year, each including 3 plasma samples (2 with and 1 without aluminium supplementation), 2 samples of water supplemented with aluminium and a blank (water). The results obtained in this scheme showed an improvement in the quality of the analyses.