Dynamique d'aimantation dans les jonctions tunnels magnétiques à anisotropie perpendiculaire

Epitaxial (MgO barrier) magnetic tunnel junctions (MTJs) are the most promising systems for applications ranging from high performance recording heads to magnetic random access memories (MRAM). Besides, such junctions also involves new and fascinating physics, such as the physics of electronic transport across epitaxial barriers, or the physics of magnetic coupling across a thin barrier. We described results obtained on MTJs perpendicular FePt/MgO/FePt magnetization. Far less studied, systems with perpendicular magnetization may have the highest potential for use at the highest recording densities in MRAM. We demonstrated that high magnetic anisotropy - L10 phase FePt layers can be grown in FePt/MgO/FePt trilayers, spontaneously with one soft and one hard layer. In addition, full magnetic decoupling is obtained in spite of the large magnetization of both layers. The manuscript then focuses on two studies. First, we observe the domain wall propagation speed on FePt single layers, as a function of both the applied field and of the layer thickness (from 2 to 6 nm), thereby extending the studies previously limited to ultrathin Pt/Co/Pt films to non-zero thicknesses. Second, we observed in details the magnetic coupling phenomena between the two FePt layers in full MTJs. By combining magneto-optical (macroscopic) studies and Magnetic Force Microscopy imaging, we gained a detailed understanding of the origin of the coupling, and of the process by which the cycling of the soft layer can induce a progressive demagnetization of the hard one.Les jonctions tunnel magnétiques (JTM) épitaxiées à barrière MgO constituent probablement le système le plus prometteur pour des applications allant depuis les têtes de lecture des disques durs jusqu'aux mémoires magnétiques à accès aléatoire. De plus, de telles jonctions mettent en jeu une physique nouvelle et fascinante, celle de la physique du transport électronique au travers de barrières épitaxiées, ou du couplage magnétique entre électrodes au travers d'une fine barrière. Nous présentons des travaux conduits sur des jonctions à perpendiculaire (FePt/MgO/FePt). Très peu étudiés, les systèmes à aimantation perpendiculaire semblent présenter le potentiel le plus élevé aux très hautes densités dans les mémoires MRAM. Nous avons montré que des jonctions FePt/MgO/FePt peuvent être obtenues avec des couches de FePt chimiquement ordonnées dans la phase L10 de très forte anisotropie magnétocristalline. Ces jonctions présentent spontanément une couche dure et une couche douce, et un découplage magnétique en dépit de la forte aimantation volumique de l'alliage FePt. La thèse porte alors principalement sur deux études : - la propagation de parois dans des films minces de FePt, en fonction du champ appliqué et de l'épaisseur de la couche mince (entre 2 et 6 nm). Nous étendons ici les études auparavant réalisées dans la limite de films ultra-minces (Pt/Co/Pt)/ - les phénomènes de couplage magnétique entre électrodes à aimantation perpendiculaire dans la jonction complète. En combinant études macroscopiques (magnéto-optiques) et locales, nous proposons une description détaillée de l'origine du couplage magnétique, et du processus qui peut conduire à la démagnétisation progressive de la couche dure lors du cyclage de la couche douce

ESSENTIAL SELF-TRAINING SKILLS TO BECOME AN INTERPRETER: ENGLISH-MAJORING STUDENTS’ PERCEPTION

Currently, interpreting has become a profession in high demand. This study surveyed students' perceptions of the essential self-training skills to become an interpreter. The study used a questionnaire to collect data collection tool which was a survey with 12 multiple-choice questions and 4 open-ended questions. 82 English–majoring students of High-quality program Batch 45 – at Can Tho University participated in the survey. The results show that students majoring in High-quality English Language perceive the importance of skills in interpreting: shorthand skills, listening comprehension skills, memorization skills, visualization skills, presentation skills, skills in using search engines, teamwork skills, multi-tasking skills, and pronunciation skills. Students also pointed out a number of skills that they think are equally important if they want to become an interpreter such as reflexes, situational skills, and contextual skills. On that basis, a number of measures of how to support students to develop their own training plans and hone their skills for their future careers are proposed.  Article visualizations

Recent progress of diamond device toward power application

International audienceThe state of the art of the Institut Néel research activity in the field of diamond power devices will be described and discussed. The active layers of the device are based on boron-doped monocristalline (100) diamond (with doping level varying between 1014 to 1021 cm-3) grown on Ib high temperature high pressure (HPHT) diamond substrate. The progresses done on diamond/metal interface, diamond/dielectric interface, or sharp gradient doping, permit recently the fabrication of original structures and devices, which will be detailed here (Schottky diode, boron doped δ-FET and MOS capacitance)

Electronic and physico-chemical properties of nanmetric boron delta-doped diamond structures

Heavily boron doped diamond epilayers with thicknesses ranging from 40 to less than 2 nm and buried between nominally undoped thicker layers have been grown in two different reactors. Two types of [100]-oriented single crystal diamond substrates were used after being characterized by X-ray white beam topography. The chemical composition and thickness of these so-called deltadoped structures have been studied by secondary ion mass spectrometry, transmission electron microscopy, and spectroscopic ellipsometry. Temperature-dependent Hall effect and four probe resistivity measurements have been performed on mesa-patterned Hall bars. The temperature dependence of the hole sheet carrier density and mobility has been investigated over a broad temperature range (6K<T<450 K). Depending on the sample, metallic or non-metallic behavior was observed. A hopping conduction mechanism with an anomalous hopping exponent was detected in the non-metallic samples. All metallic delta-doped layers exhibited the same mobility value, around 3.660.8 cm2/Vs, independently of the layer thickness and the substrate type. Comparison with previously published data and theoretical calculations showed that scattering by ionized impurities explained only partially this low common value. None of the delta-layers showed any sign of confinement-induced mobility enhancement, even for thicknesses lower than 2 nm.14 page

The Role of Maternally Acquired Antibody in Providing Protective Immunity Against Nontyphoidal Salmonella in Urban Vietnamese Infants: A Birth Cohort Study.

BACKGROUND: Nontyphoidal Salmonella (NTS) organisms are a major cause of gastroenteritis and bacteremia, but little is known about maternally acquired immunity and natural exposure in infant populations residing in areas where NTS disease is highly endemic. METHODS: We recruited 503 pregnant mothers and their infants (following delivery) from urban areas in Vietnam and followed infants until they were 1 year old. Exposure to the dominant NTS serovars, Salmonella enterica serovars Typhimurium and Enteritidis, were assessed using lipopolysaccharide (LPS) O antigen-specific antibodies. Antibody dynamics, the role of maternally acquired antibodies, and NTS seroincidence rates were modeled using multivariate linear risk factor models and generalized additive mixed-effect models. RESULTS: Transplacental transfer of NTS LPS-specific maternal antibodies to infants was highly efficient. Waning of transplacentally acquired NTS LPS-specific antibodies at 4 months of age left infants susceptible to Salmonella organisms, after which they began to seroconvert. High seroincidences of S. Typhimurium and S. Enteritidis LPS were observed, and infants born with higher anti-LPS titers had greater plasma bactericidal activity and longer protection from seroconversion. CONCLUSIONS: Although Vietnamese infants have extensive exposure to NTS, maternally acquired antibodies appear to play a protective role against NTS infections during early infancy. These findings suggest that prenatal immunization may be an appropriate strategy to protect vulnerable infants from NTS disease

Panta Rhei benchmark dataset: socio-hydrological data of paired events of floods and droughts

As the adverse impacts of hydrological extremes increase in many regions of the world, a better understanding of the drivers of changes in risk and impacts is essential for effective flood and drought risk management and climate adaptation. However, there is currently a lack of comprehensive, empirical data about the processes, interactions and feedbacks in complex human-water systems leading to flood and drought impacts. Here we present a benchmark dataset containing socio-hydrological data of paired events, i.e., two floods or two droughts that occurred in the same area. The 45 paired events occurred in 42 different study areas and cover a wide range of socio-economic and hydro-climatic conditions. The dataset is unique in covering both floods and droughts, in the number of cases assessed, and in the quantity of socio-hydrological data. The benchmark dataset comprises: 1) detailed review style reports about the events and key processes between the two events of a pair; 2) the key data table containing variables that assess the indicators which characterise management shortcomings, hazard, exposure, vulnerability and impacts of all events; 3) a table of the indicators-of-change that indicate the differences between the first and second event of a pair. The advantages of the dataset are that it enables comparative analyses across all the paired events based on the indicators-of-change and allows for detailed context- and location-specific assessments based on the extensive data and reports of the individual study areas. The dataset can be used by the scientific community for exploratory data analyses e.g. focused on causal links between risk management, changes in hazard, exposure and vulnerability and flood or drought impacts. The data can also be used for the development, calibration and validation of socio-hydrological models. The dataset is available to the public through the GFZ Data Services (Kreibich et al. 2023, link for review: https://dataservices.gfz-potsdam.de/panmetaworks/review/923c14519deb04f83815ce108b48dd2581d57b90ce069bec9c948361028b8c85/).</p

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Dynamique d'aimantation dans les jonctions tunnels magnétiques à anisotropie perpendiculaire

Epitaxial (MgO barrier) magnetic tunnel junctions (MTJs) are the most promising systems for applications ranging from high performance recording heads to magnetic random access memories (MRAM). Besides, such junctions also involves new and fascinating physics, such as the physics of electronic transport across epitaxial barriers, or the physics of magnetic coupling across a thin barrier. We described results obtained on MTJs perpendicular FePt/MgO/FePt magnetization. Far less studied, systems with perpendicular magnetization may have the highest potential for use at the highest recording densities in MRAM. We demonstrated that high magnetic anisotropy - L10 phase FePt layers can be grown in FePt/MgO/FePt trilayers, spontaneously with one soft and one hard layer. In addition, full magnetic decoupling is obtained in spite of the large magnetization of both layers. The manuscript then focuses on two studies. First, we observe the domain wall propagation speed on FePt single layers, as a function of both the applied field and of the layer thickness (from 2 to 6 nm), thereby extending the studies previously limited to ultrathin Pt/Co/Pt films to non-zero thicknesses. Second, we observed in details the magnetic coupling phenomena between the two FePt layers in full MTJs. By combining magneto-optical (macroscopic) studies and Magnetic Force Microscopy imaging, we gained a detailed understanding of the origin of the coupling, and of the process by which the cycling of the soft layer can induce a progressive demagnetization of the hard one.Les jonctions tunnel magnétiques (JTM) épitaxiées à barrière MgO constituent probablement le système le plus prometteur pour des applications allant depuis les têtes de lecture des disques durs jusqu'aux mémoires magnétiques à accès aléatoire. De plus, de telles jonctions mettent en jeu une physique nouvelle et fascinante, celle de la physique du transport électronique au travers de barrières épitaxiées, ou du couplage magnétique entre électrodes au travers d'une fine barrière. Nous présentons des travaux conduits sur des jonctions à perpendiculaire (FePt/MgO/FePt). Très peu étudiés, les systèmes à aimantation perpendiculaire semblent présenter le potentiel le plus élevé aux très hautes densités dans les mémoires MRAM. Nous avons montré que des jonctions FePt/MgO/FePt peuvent être obtenues avec des couches de FePt chimiquement ordonnées dans la phase L10 de très forte anisotropie magnétocristalline. Ces jonctions présentent spontanément une couche dure et une couche douce, et un découplage magnétique en dépit de la forte aimantation volumique de l'alliage FePt. La thèse porte alors principalement sur deux études : - la propagation de parois dans des films minces de FePt, en fonction du champ appliqué et de l'épaisseur de la couche mince (entre 2 et 6 nm). Nous étendons ici les études auparavant réalisées dans la limite de films ultra-minces (Pt/Co/Pt)/ - les phénomènes de couplage magnétique entre électrodes à aimantation perpendiculaire dans la jonction complète. En combinant études macroscopiques (magnéto-optiques) et locales, nous proposons une description détaillée de l'origine du couplage magnétique, et du processus qui peut conduire à la démagnétisation progressive de la couche dure lors du cyclage de la couche douce

Comparative Study of the Silver Nanoparticle Synthesis Ability and Antibacterial Activity of the Piper Betle L. and Piper Sarmentosum Roxb. Extracts

Piper betle (P. betle) and Piper sarmentosum (P. sarmentosum) are the two members of the Piper genus, have been reported to be rich in phytochemicals and essential oils, which showed strong reducing power, antibacterial, and antifungal activities. P. betle recently has been studied and applied in several commercial products in the antimicrobial respect, meanwhile its relatives, P. sarmentosum has been lesser-known in this field. In this study, the two Piper species—P. betle and P. sarmentosum were studied to compare their ability in silver nanoparticle synthesis and efficacy in antibacterial activity. P. betle and P. sarmentosum were extracted by distilled water at different temperatures and times. Subsequently, their total reducing capacity was determined by DPPH scavenging and Folin-Ciocalteu assays to choose the appropriate extraction conditions. The silver nanoparticle solutions prepared by the extracts of P. betle (Pb.ext) and P. sarmentosum (Ps.ext) were characterized by Dynamic light scattering (DLS), Zeta potential, UV-vis, and Fourier-transform infrared (FTIR) measurements. Finally, the antibacterial activity of the synthesized silver nanoparticle solutions was tested against Escherichia coli using the agar diffusion well–variant method. The Pb.ext showed stronger reducing power with higher total polyphenol content (~125 mg GAE/mL extract) and better DPPH activity (IC50~1.45%). Both the green synthesized silver nanoparticle solutions (Pb.AgNP and Ps.AgNP) performed significantly stronger antibacterial activity on Escherichia coli compared to their initial extracts. Antibacterial tests revealed that Ps.AgNP showed remarkably better growth inhibition activity as compared to Pb.AgNP. This study would contribute useful and important information to the development of antibacterial products based on green synthesized silver nanoparticles fabricated by the extracts of P. betle and P. sarmentosum