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2.
Phys Rev Lett ; 129(3): 035501, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35905331

RESUMO

How are nuclear quantum fluctuations affecting the properties of dense hydrogen approaching metallization? We report here Raman spectroscopy and synchrotron infrared absorption measurements on deuterium up to 460 GPa at 80 K. By comparing to a previous similar study on hydrogen, isotopic effects on the electronic and vibrational properties in phase III are disclosed. Also, evidence of a probable transition to metal deuterium is observed, shifted by about 35 GPa compared to that in hydrogen. Advanced calculations, quantifying a reduction of the band gap caused by nuclear quantum fluctuations, are compared to the present data.

3.
J Synchrotron Radiat ; 29(Pt 1): 167-179, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34985434

RESUMO

Results of the 2018 commissioning and experimental campaigns of the new High Power Laser Facility on the Energy-dispersive X-ray Absorption Spectroscopy (ED-XAS) beamline ID24 at the ESRF are presented. The front-end of the future laser, delivering 15 J in 10 ns, was interfaced to the beamline. Laser-driven dynamic compression experiments were performed on iron oxides, iron alloys and bismuth probed by online time-resolved XAS.

4.
Data Brief ; 37: 107220, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34195307

RESUMO

The integration of multidimensional data is necessary to improve the understanding of environmental and social inequalities in health. The challenge is to define a dataset that provides the most holistic description possible of the territory. This article presents a relevant dataset to characterize the territorial accumulation of health determinants in the second most densely populated region of metropolitan France (Hauts-de-France Region, in the north of France). The multidimensional dataset combines data related to the economic, social, environment, services, health and policy dimensions at fine scale (i.e., each municipality). Data outlining a negative impact on health inequalities (e.g. anthropogenic pressures, socioeconomics factors related to vulnerability, etc.) are considered to be as important as data outlining a positive impact on health inequalities (e.g. natural resources, diversity and economic drive, etc.). The proposed theoretical framework relies on data reuse. Over one hundred variables covering a time frame from 2008 to 2017 were collected from a dozen public and national database providers. The use of official organizations ensured the quality of the collected data. The Geographic Information System, designed to map and catalogue ready-to-use data, was used to generate new data or to deal with missing data. Finally, 50 variables, including mostly quantitative but also qualitative data, were selected after application of inclusion and exclusion criteria. The resulting dataset provides a broad characterisation of the 3,817 municipalities in the Hauts-de-France Region. These data will help to discriminate the distribution pattern of vulnerability and resilience levels in this region. This novel approach is described in the paper "How can we analyse environmental health resilience and vulnerability? A joint analysis with composite indices applied to the north of France", which provides a detailed description of the methodology used to develop composite indices. This research could therefore be of use to researchers, policy makers and stakeholders in the field of environmental health seeking to identify the weaknesses but also the strengths of municipalities.

5.
Sci Total Environ ; 772: 144877, 2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-33770881

RESUMO

BACKGROUND: Although walkability is known to be associated with obesity and hypertension through increased physical activity; data on cardiovascular risk factors (especially in the Europe) are scarce. We assessed the relationship between neighbourhood walkability and cardiometabolic factors (including obesity, hypertension, the blood lipid profile, and serum glycated haemoglobin (HbA1c) levels) among adults living in northern France. METHODS: Data were extracted from the ELISABET study database (2011-2013). The participants (aged between 40 and 65) resided in or around the cities of Lille and Dunkirk. For each residential address, we determined a neighbourhood walkability index (using a geographic information system) and the Walk Score®. Multilevel linear and logistic models were used to assess the relationships between neighbourhood walkability on one hand and body mass index (BMI), obesity, blood pressure, hypertension, serum HDLC, LDL-C, triglyceride and HbA1c levels, and physical activity level on the other. RESULTS: 3218 participants were included. After adjusting for individual and neighbourhood variables, we found that a higher neighbourhood walkability index was associated with a lower BMI (-0.23 kg.m-2; 95% confidence interval (CI) [-0.44;-0.01] for a one interquartile range (IQR) increment), a lower systolic blood pressure (-1.66 mmHg; 95% CI [-2.46;-0.85] per IQR), a lower prevalence of hypertension (% of increase: -7.12, 95% CI [-13.56;-0.52] per IQR), and a higher prevalence of moderate or high physical activity (% of increase = 6.9; 95% CI [1.2;12.72] per IQR). The walkability index was not significantly associated with other cardiovascular risk factors. Similar results were observed for the Walk Score®. CONCLUSION: Our results showed that residence in a more walkable neighbourhood was associated with a lower prevalence of vascular risk factors. Promoting neighbourhood walkability might help to improve the population's cardiovascular health.


Assuntos
Doenças Cardiovasculares , Planejamento Ambiental , Adulto , Idoso , Doenças Cardiovasculares/epidemiologia , Cidades , Estudos Transversais , Europa (Continente) , França/epidemiologia , Fatores de Risco de Doenças Cardíacas , Humanos , Pessoa de Meia-Idade , Características de Residência , Fatores de Risco , Caminhada
6.
Sci Total Environ ; 763: 142983, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33131849

RESUMO

In environmental health, vulnerability reflecting the cumulative harmful constraints and nuisances to which populations are subjected and resilience defined as the capacity of a territory to cope with health inequalities have been little extensively investigated together with the same importance. Besides the diversity of factors involved, there is no consensual framework to develop composite indices, one recognized methodology to deal with a multifaceted issue. Therefore, this research aims to establish a new transferable approach to assess the spatial heterogeneity of territorial inequalities. This new strategy relies on the simultaneous evaluation of resilience and vulnerability and the joint analysis based on the cross-interpretation of the spatialized composite indices of resilience and vulnerability. A case study was conducted to demonstrate the feasibility of this methodology, using the municipality as a spatial unit of analysis within a region in the north of France. To provide the most holistic description possible of the 3817 studied municipalities, 50 variables related to the economic, environment, policy, health, services and social dimensions were used to develop the composite indices. The vulnerability Index has a median value of 0.151 with an IQR of [0.126-0.180] and the Resilience Index has a median value of 0.341 with an IQR of [0.273-0.401]. The joint analysis was conducted to classify each municipality among four defined typologies: 1687 municipalities (44.2%) belong to the "To monitor" category, 1646 (43.1%) to the "Resilient" category, 329 (8.6%) to the "Have resources" category and 155 (4.1%) to the "Territorial blackspot" category. The methodology herein may be a diagnostic tool to identify and prioritize municipalities that could benefit from the implementation of specifically tailored public health policies.

7.
BMC Pediatr ; 20(1): 442, 2020 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-32957953

RESUMO

BACKGROUND: Strong evidence for a causal role of environmental factors in a congenital anomaly is still difficult to produce. The collection of statistical data is crucial for gaining a better understanding of the epidemiology and pathophysiology of these anomalies. We aimed to evaluate spatial variations in hypospadias within our region and it's association to socioeconomic and ecological factors, taking clinical data into account. METHODS: All boys with hypospadias born in northern France and seen in Lille University Medical Center (Lille, France) between 1999 and 2012 were included in the analysis. We retrospectively collected geographic data, clinical data (especially known confounding factors associated with an elevated risk of hypospadias), and demographic, socio-economic and ecological data. We analyzed the entire study population and subsequently the subset of boys lacking confounding factors. RESULTS: The study sample of 975 cases of hypospadias over the 13-year period resulted in an incidence of 25.4/10,000 male births, and was characterized by significant spatial heterogeneity (p < 0.005) and autocorrelation (p < 0.001). We detected two high-incidence clusters that differed with regard to their land use. After the exclusion of 221 patients with confounding factors, two high-incidence clusters with significant disease risks (1.65 and 1.75, respectively; p < 0.001) and a significant difference in land use (p < 0.001) again appeared. The first cluster contained a higher median [interquartile range] proportion of artificialized land (0.40 [0.22;0.47]) than the remaining "neutral areas" (0.19 [0.08;0.53]) did (p < 0.001). Conversely, the second cluster contained a higher median proportion of rural land (0.90 [0.78;0.96]) than the "neutral areas" (0.81 [0.47;0.92]) did (p < 0.001). The median deprivation index was significantly lower in the urban cluster (0.47 [0.42;0.55]) and significantly higher in the rural cluster (0.69 [0.56;0.73]) (p < 0.001). CONCLUSIONS: Our results evidenced the heterogeneous spatial distribution of cases of hypospadias in northern France. We identified two clusters with different environmental and social patterns - even after the exclusion of known confounding factors.


Assuntos
Hipospadia , França/epidemiologia , Humanos , Hipospadia/epidemiologia , Hipospadia/etiologia , Incidência , Masculino , Estudos Retrospectivos , Análise Espacial
8.
Environ Pollut ; 263(Pt B): 114599, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32325248

RESUMO

Although the incidence of Crohn's disease has increased worldwide over the past 30 years, the disorder's exact causes and physiological mechanisms have yet to be determined. Given that genetic determinants alone do not explain the development of Crohn's disease, there is growing interest in "environmental" determinants. In medical science, the term "environment" refers to both the ecological and social surroundings; however, most published studies have focused on the latter. In environmental and exposure sciences, the term "environment" mostly relates to contamination of the biotope. There are many unanswered questions on how environmental hazards might contribute to the pathogenesis of Crohn's disease. Which pollutants should be considered? Which mechanisms are involved? And how should environmental contamination and exposure be evaluated? The objective was to perform a systematic review of the literature on Crohn's disease and environmental contamination. We searched the PubMed, Google Scholar, Scopus, ISI Web of Science and Prospero databases. We considered all field studies previous to April 2019 conducted on human health indicators, and evaluating exposure to all type of physical, biological and chemical contamination of the environment. The lack of clear answers to date can be ascribed to the small total number of field studies (n = 16 of 39 publications, most of which were conducted by pioneering medical scientists), methodological differences, and the small number of contaminants evaluated. This make it impossible to conduct a coherent and efficient meta-analysis. Based on individual analysis of available studies, we formulated five recommendations on improving future research: (i) follow up the currently identified leads - especially metals and endocrine disruptors; (ii) explore soil contamination; (iii) gain a better knowledge of exposure mechanisms by developing transdisciplinary studies; (iv) identify the most plausible contaminants by developing approaches based on the source-to-target distance; and (v) develop registries and cohort-based analyses.


Assuntos
Doença de Crohn , Disruptores Endócrinos , Poluentes Ambientais , Poluição Ambiental , Humanos , Incidência
9.
Sci Total Environ ; 714: 136608, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32018947

RESUMO

Geographical variations in cardiovascular disease rates have been linked to individual air pollutants. Investigating the relation between cardiovascular disease and exposure to a complex mixture of air pollutants requires holistic approaches. We assessed the relationship between exposure to multiple air pollutants and the incidence of coronary heart disease (CHD) in a general population sample. We collected data in the Lille MONICA registry (2008-2011) on 3268 incident cases (age range: 35-74). Based on 20 indicators, we derived a composite environmental score (SEnv) for cumulative exposure to air pollution. Poisson regression models were used to analyse associations between CHD rates on one hand and SEnv and each single indicator on the other (considered in tertiles, where T3 is the most contaminated). We adjusted models for age, sex, area-level social deprivation, and neighbourhood spatial structure. The incidence of CHD was a spatially heterogeneous (p=0.006). There was a significant positive association between SEnv and CHD incidence (trend p=0.0151). The relative risks [95%CI] of CHD were 1.08 [0.98-1.18] and 1.16 [1.04-1.29] for the 2nd and 3rd tertile of SEnv exposure. In the single pollutant analysis, PM10, NO2, cadmium, copper, nickel, and palladium were significantly associated with CHD rates. Multiple air pollution was associated with an increased risk of CHD. Single pollutants reflecting road traffic pollution were the most strongly associated with CHD. Our present results are consistent with the literature data on the impact of road traffic on the CHD risk in urban areas.


Assuntos
Doença das Coronárias , Adulto , Idoso , Poluentes Atmosféricos , Poluição do Ar , Exposição Ambiental , Humanos , Incidência , Pessoa de Meia-Idade , Material Particulado
10.
Environ Res ; 183: 109161, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32000005

RESUMO

Although a growing body of evidence suggests that chronic exposure to outdoor air pollution is linked to a decline in lung function, data on flow at low lung volumes that may be more specific of small airway obstruction are still scarce. We aimed to study the associations between residential exposure to air pollution and lung function, with specific focus on small airways obstruction. We assessed 2995 French participants (aged between 40 and 65) in the ELISABET cross-sectional survey. Residential exposures to nitrogen dioxide (NO2), particulate matter with a diameter <10 µm (PM10) and sulphur dioxide (SO2) were assessed. The spirometric parameters were forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and forced expiratory flow between 25% and 75% of FVC (FEF25-75) and at 75% of FVC (FEF75). Coefficients in linear regression models were expressed as the z-score [95% confidence interval] for an increment of 5 µg/m3 in NO2 and 2 µg/m3 in PM10 and SO2. NO2 was associated with significantly lower values of FEV1 (-0.10 [-0.15;-0.05]), FVC (-0.06 [-0.11;-0.02]), FEV1/FVC (-0.07 [-0.11;-0.03]), FEF25-75 (-0.09 [-0.14;-0.05]) and FEF75 (-0.08 [-0.12;-0.04]). PM10 was associated with significantly lower values of FEV1 (-0.10 [-0.15;-0.04]), FVC (-0.06 [-0.11;-0.01]), FEV1/FVC (-0.06 [‒0.11;-0.01]), FEF25-75 (-0.08 [-0.13;-0.03]) and FEF75 (-0.08 [-0.12;-0.04]). SO2 was associated with significantly lower values of FEV1 (-0.09 [-0.16;-0.02]), FEV1/FVC (-0.07 [-0.13;-0.01]), FEF25-75 (-0.09 [-0.15;-0.02]) and FEF75 (-0.08 [-0.14;-0.03]) but not FVC (-0.05 [-0.11; 0.009]). Even though spatial variations in pollutant levels were low, residential exposure to outdoor air pollution was associated with lower lung function, including lower FEF25-75 and FEF75 suggesting small airway obstruction.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Obstrução das Vias Respiratórias , Pulmão , Adulto , Idoso , Poluentes Atmosféricos/toxicidade , Obstrução das Vias Respiratórias/etiologia , Estudos Transversais , Exposição Ambiental , Volume Expiratório Forçado , Humanos , Pulmão/efeitos dos fármacos , Pulmão/fisiopatologia , Pessoa de Meia-Idade , Material Particulado , Capacidade Vital
11.
Nature ; 577(7792): 631-635, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31996819

RESUMO

Hydrogen has been an essential element in the development of atomic, molecular and condensed matter physics1. It is predicted that hydrogen should have a metal state2; however, understanding the properties of dense hydrogen has been more complex than originally thought, because under extreme conditions the electrons and protons are strongly coupled to each other and ultimately must both be treated as quantum particles3,4. Therefore, how and when molecular solid hydrogen may transform into a metal is an open question. Although the quest for metal hydrogen has pushed major developments in modern experimental high-pressure physics, the various claims of its observation remain unconfirmed5-7. Here a discontinuous change of the direct bandgap of hydrogen, from 0.6 electronvolts to below 0.1 electronvolts, is observed near 425 gigapascals. This result is most probably associated with the formation of the metallic state because the nucleus zero-point energy is larger than this lowest bandgap value. Pressures above 400 gigapascals are achieved with the recently developed toroidal diamond anvil cell8, and the structural changes and electronic properties of dense solid hydrogen at 80 kelvin are probed using synchrotron infrared absorption spectroscopy. The continuous downward shifts of the vibron wavenumber and the direct bandgap with increased pressure point to the stability of phase-III hydrogen up to 425 gigapascals. The present data suggest that metallization of hydrogen proceeds within the molecular solid, in good agreement with previous calculations that capture many-body electronic correlations9.

12.
Aliment Pharmacol Ther ; 51(1): 139-148, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31588597

RESUMO

BACKGROUND: Geographical variations in Crohn's disease (CD) suggest that the environment has a role in the pathogenesis of this condition. AIMS: To describe the spatial distribution and the clustering of CD cases in France, and to assess the relationship between the prevalence of CD and environmental risk factors. METHODS: We identified all patients with CD included in the French hospital discharge database from 2007 to 2014. Age- and gender-smoothed standardised prevalence ratios over this period were computed for 5610 spatial units. An ecological regression analysis was used to assess the relationship between the risk of CD and ecological variables (health care, latitude, socio-economic deprivation, urbanisation, proportion of agricultural surfaces and density of industries). Local spatial clusters of high-CD prevalence were searched for using elliptic spatial scan statistics and characterised in a hierarchical ascendant classification based on the same ecological variables. RESULTS: About 129 089 patients with CD were identified, yielding a crude prevalence of 203 per 100 000 inhabitants. The overall spatial heterogeneity was statistically significant (P < .001). An elevated risk of CD was found to be significantly associated with high-social deprivation (relative risk [95% confidence interval] = 1.05 [1.02-1.08]) and high urbanisation (1.09 [1.04-1.14]). Sixteen significant spatial clusters of high-CD prevalence were identified; there were no common ecological variables. CONCLUSIONS: The geographical distribution of CD prevalence in France is not uniform, and is associated with high levels of social deprivation and urbanisation. Larger ecological databases integrating more detailed environmental and clinical information are needed.


Assuntos
Doença de Crohn/epidemiologia , Meio Ambiente , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Bases de Dados Factuais , Feminino , França/epidemiologia , Geografia , História do Século XXI , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Alta do Paciente/estatística & dados numéricos , Prevalência , Fatores de Risco , Determinantes Sociais da Saúde/estatística & dados numéricos , Fatores Socioeconômicos , População Urbana/estatística & dados numéricos , Adulto Jovem
13.
Science ; 366(6471): 1359-1362, 2019 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-31831664

RESUMO

Pressure can be used to tune the interplay among structural, electronic, and magnetic interactions in materials. High pressures are usually applied in the diamond anvil cell, making it difficult to study the magnetic properties of a micrometer-sized sample. We report a method for spatially resolved optical magnetometry based on imaging a layer of nitrogen-vacancy (NV) centers created at the surface of a diamond anvil. We illustrate the method using two sets of measurements realized at room temperature and low temperature, respectively: the pressure evolution of the magnetization of an iron bead up to 30 gigapascals showing the iron ferromagnetic collapse and the detection of the superconducting transition of magnesium dibromide at 7 gigapascals.

14.
Cancer Manag Res ; 11: 8337-8344, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31571990

RESUMO

Background: Somatic mutations in the KRAS gene are the most common oncogenic mutations found in human cancers. However, no clinical features have been linked to KRAS mutations in colorectal cancer [CRC]. Purpose: In this study, we attempted to identify the potential geographical population clusters of KRAS mutations in CRC patients in northern France. Patients and methods: All patients with CRC who were identified to have KRAS mutations between 2008 and 2014 at the Regional Molecular Biology Platform at Lille University Hospital were included. 2,486 patients underwent a KRAS status available, with 40.9% of CRC with KRAS mutations in northern France. We retrospectively collected demographic and geographic data from these patients. The proportions of KRAS mutation were smoothed to take into account the variability related to low frequencies and spatial autocorrelation. Geographical clusters were searched using spatial scan statistical models. Results: A mutation at KRAS codon 12 or 13 was found in 1,018 patients [40.9%]. We report 5 clusters of over-incidence but only one elongated cluster that was statistically significant [Cluster 1; proportion of KRAS mutation among CRC: 0.4570; RR=1.29; P=0.0314]. We made an ecological study which did not highlight a significant association between KRAS mutations and the distance to the Closest Waste Incineration Plant, and between KRAS mutations and The French Ecological Deprivation Index but few socio-economic and environmental data were available. Conclusion: There was a spatial heterogeneity and a greater frequency of KRAS mutations in some areas close to major highways and big cities in northern France. These data demand deeper epidemiological investigations to identify environmental factors such as air pollution as key factors in the occurrence of KRAS mutations.

15.
Environ Int ; 120: 121-129, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30077944

RESUMO

INTRODUCTION: A growing body of evidence suggests that long-term exposure to air pollutants like nitrogen oxides (NOx) and particulate matter (PM) is associated with the prevalence and incidence of type 2 diabetes mellitus. Serum glucose and glycosylated hemoglobin (HbA1c) levels are biomarkers of glucose homeostasis. Data on the association between glucose homeostasis biomarkers and air pollution are scarce. HbA1c and fasting blood glucose (FBG) concentrations have been linked to PM and NO2 exposure in Taiwan, where mean pollution levels are 3 to 7 times higher than the guideline maximum annual mean values of 40 µg/m3 (for NO2) and 20 µg/m3 (for PM10) set by the World Health Organization (WHO). However, this association is not consistently reported at lower levels of pollution. The objective of the present study was to investigate the relationships between long-term exposure to air pollution at the place of residence, diabetes biomarkers, and prevalent diabetes in two cities with relatively low level of pollution. METHODS: Data were recorded for 2895 adults (aged 40 to 65) having participated in the 2011-2013 ELISABET cross-sectional survey of the Lille and Dunkirk urban areas in northern France. Using multiple logistic and generalized linear regression models, we analyzed the associations between individual exposure to pollution on one hand and HbA1c, FBG and prevalent diabetes mellitus (DM) on the other. An atmospheric dispersion modelling system was used to assess annual exposure at the place of residence to coarse particulate matter (PM10), NO2, and sulfur dioxide (SO2). RESULTS: The median pollutant levels were 21.96 µg/m3 for NO2, 26.75 µg/m3 for PM10, and 3.07 µg/m3 for SO2. A 2 µg/m3 increment in PM10 was associated with an HbA1c increment [95% confidence interval] of 0.044% [0.021; 0.067]. This association was still statistically significant after adjustment for the neighborhood's characteristics. A 5 µg/m3 increment in NO2 was associated with an HbA1c increment of 0.031% [0.010; 0.053]. Associations between DM or FBG and air pollution did not achieve statistical significance. CONCLUSION: Our study of a middle-aged, urban population evidenced an association between elevated HbA1c levels and long-term exposure to PM10 and NO2 pollution levels that were relatively low but close to the WHO's guideline maximum values.


Assuntos
Poluentes Atmosféricos/análise , Glicemia/análise , Diabetes Mellitus Tipo 2 , Exposição Ambiental , Hemoglobina A Glicada/análise , Adulto , Idoso , Estudos Transversais , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/epidemiologia , Exposição Ambiental/análise , Exposição Ambiental/estatística & dados numéricos , França/epidemiologia , Humanos , Pessoa de Meia-Idade
16.
Nat Commun ; 9(1): 2913, 2018 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-30046093

RESUMO

Over the past 60 years, the diamond anvil cell (DAC) has been developed into a widespread high static pressure device. The adaptation of laboratory and synchrotron analytical techniques to DAC enables a detailed exploration in the 100 GPa range. The strain of the anvils under high load explains the 400 GPa limit of the conventional DAC. Here we show a toroidal shape for a diamond anvil tip that enables to extend the DAC use toward the terapascal pressure range. The toroidal-DAC keeps the assets for a complete, reproducible, and accurate characterization of materials, from solids to gases. Raman signal from the diamond anvil or X-ray signal from the rhenium gasket allow measurement of pressure. Here, the equations of state of gold, aluminum, and argon are measured with X-ray diffraction. The data are compared with recent measurements under similar conditions by two other approaches, the double-stage DAC and the dynamic ramp compression.

17.
Sci Rep ; 6: 26402, 2016 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-27246145

RESUMO

Understanding Warm Dense Matter (WDM), the state of planetary interiors, is a new frontier in scientific research. There exists very little experimental data probing WDM states at the atomic level to test current models and those performed up to now are limited in quality. Here, we report a proof-of-principle experiment that makes microscopic investigations of materials under dynamic compression easily accessible to users and with data quality close to that achievable at ambient. Using a single 100 ps synchrotron x-ray pulse, we have measured, by K-edge absorption spectroscopy, ns-lived equilibrium states of WDM Fe. Structural and electronic changes in Fe are clearly observed for the first time at such extreme conditions. The amplitude of the EXAFS oscillations persists up to 500 GPa and 17000 K, suggesting an enduring local order. Moreover, a discrepancy exists with respect to theoretical calculations in the value of the energy shift of the absorption onset and so this comparison should help to refine the approximations used in models.

18.
Proc Natl Acad Sci U S A ; 112(25): 7673-6, 2015 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-26056306

RESUMO

The prediction of novel lithium hydrides with nontraditional stoichiometries at high pressure has been seminal for highlighting a promising line of research on hydrogen-dense materials. Here, we report the evidences of the disproportionation of LiH above 130 GPa to form lithium hydrides containing H2 units. Measurements have been performed using the nonperturbing technique of synchrotron infrared absorption. The observed vibron frequencies match the predictions for LiH2 and LiH6. These polyhydrides remain insulating up to 215 GPa. A disproportionation mechanism based on the diffusion of lithium into the diamond anvil and a stratification of the sample into LiH6/LiH2/LiH layers is proposed. Polyhydrides containing an H2 sublattice do exist and could be ubiquitously stable at high pressure.

19.
PLoS One ; 9(11): e110132, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25365039

RESUMO

BACKGROUND: Strong geographic variations in the incidence of end-stage renal disease (ESRD) are observed in developed countries. The reasons for these variations are unknown. They may reflect regional inequalities in the population's sociodemographic characteristics, related diseases, or medical practice patterns. In France, at the district level, the highest incidence rates have been found in the Nord-Pas-de-Calais region. This area, with a high population density and homogeneous healthcare provision, represents a geographic situation which is quite suitable for the study, over small areas, of spatial disparities in the incidence of ESRD, together with their correlation with a deprivation index and other risk factors. METHODS: The Renal Epidemiology and Information Network is a national registry, which lists all ESRD patients in France. All cases included in the Nord-Pas-de-Calais registry between 2005 and 2011 were extracted. Adjusted and smoothed standardized incidence ratio (SIR) was calculated for each of the 170 cantons, thanks to a hierarchical Bayesian model. The correlation between ESRD incidence and deprivation was assessed using the quintiles of Townsend index. Relative risk (RR) and credible intervals (CI) were estimated for each quintile. RESULTS: Significant spatial disparities in ESRD incidence were found within the Nord-Pas-de-Calais region. The sex- and age-adjusted, smoothed SIRs varied from 0.66 to 1.64. Although no correlation is found with diabetic or vascular nephropathy, the smoothed SIRs are correlated with the Townsend index (RR: 1.18, 95% CI [1.00-1.34] for Q2; 1.28, 95% CI [1.11-1.47] for Q3; 1.30, 95% CI [1.14-1.51] for Q4; 1.44, 95% CI [1.32-1.74] for Q5). CONCLUSION: For the first time at this aggregation level in France, this study reveals significant geographic differences in ESRD incidence. Unlike the time of renal replacement care, deprivation is certainly a determinant in this phenomenon. This association is probably independent of the patients' financial ability to gain access to healthcare.


Assuntos
Falência Renal Crônica/epidemiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , França/epidemiologia , Humanos , Incidência , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Sistema de Registros , Fatores de Risco , Análise Espacial , Topografia Médica , Adulto Jovem
20.
Phys Rev Lett ; 97(21): 215504, 2006 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-17155749

RESUMO

The compression curve of iron is measured up to 205 GPa at 298 K, under quasihydrostatic conditions in a diamond anvil cell. Above 150 GPa, the compression of this metal is significantly higher than previously measured under nonhydrostatic conditions. The same compression curve is also calculated ab initio and the deviation between experiment and theory is clearly established. A formulation of the equation of state of iron over a large pressure and temperature range, based on the current data and existing shock-wave data, is also proposed. Implications for the Earth's core are discussed.

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