Modèles de coût pour la sélection de vues matérialisées dans le nuage, application aux services Amazon EC2 et S3

National audienceDans les bases et entrepôts de données, la performance des requêtes est classiquement assurée grâce à des structures comme les caches, les index et les vues matérialisées. Dans ce contexte, des modèles de coût permettent de sélectionner un ensemble efficace de ce type de structures. Toutefois, cette tâche de sélection devient plus complexe dans le nuage, car en plus des temps de réponse, il faut simultanément optimiser le coût monétaire d'utilisation du nuage. En conséquence, nous proposons dans cet article de nouveaux modèles de coût qui intègrent le paradigme de paiement à la demande en vigueur dans les nuages informatiques. Sur la base de ces modèles, nous définissons un problème d'optimisation consistant à sélectionner, parmi un ensemble de vues candidates, celles qu'il faut matérialiser pour minimiser le coût d'interrogation et de maintenance de la base de données, ainsi que le temps de réponse à une charge de requêtes donnée. Dans un premier temps, nous optimisons les deux critères précédents séparément: le temps de réponse est optimisé sous contrainte de coût et vice versa. Les expériences que nous avons menées pour valider cette proposition montrent que la matérialisation de vues dans le nuage est toujours avantageuse

CoFe2O4/buffer layer ultrathin heterostructures on Si(001)

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.Epitaxial films of ferromagnetic CoFe2O4 (CFO) were grown by pulsed laser deposition on Si(001) buffered with ultrathin yttria-stabilized zirconia (YSZ) layers in a single process. Reflection high-energy electron diffraction was used to monitor in real time the crystallization of YSZ, allowing the fabrication of epitaxial YSZ buffers with thickness of about 2 nm. CFO films, with thicknesses in the 2-50 nm range were subsequently deposited. The magnetization of the CFO films is close to the bulk value. The ultrathin CFO/YSZ heterostructures have very flat morphology (0.1 nm roughness) and thin interfacial SiOx layer (about 2 nm thick) making them suitable for integration in tunnel (e.g., spin injection) devices

Poisson ratio and bulk lattice constant of (Sr 0.25 La 0.75 )CrO 3 from strained epitaxial thin films

International audienceAbout 30 nm thick (001)-oriented (Sr0.25La0.75)CrO3 (SLCO) epitaxial thin films were grown by solid-source oxide molecular beam epitaxy on four different single-crystalline cubic or pseudo-cubic (001)-oriented oxide substrates: LaAlO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, SrTiO3 and DyScO3, which result in lattice mismatch ranging from-2% to +1.7%. All the films are of high-quality, flat and strained by the substrates. By assessing the evolution of the out-of-plane lattice parameter as a function of the in-plane lattice parameter of the samples, we determine both the Poisson ratio (ν = 0.32) and the bulk lattice constant (ab = 3.876 Å) of SLCO. The Poisson ratio significantly differs from LaCrO3 (ν = 0.23) and the (SrxLa1-x)CrO3 solid solution appears to obey structural Vegard's law. Since SLCO is the only one p-type transparent conductive oxide of perovskite structure and has promising thermoelectric properties, integrating SLCO in heterostructures and devices is therefore of paramount importance, which confers on our results their strong interest. Besides, the method used here can be straightforwardly applied to other complex oxides

Domain matching epitaxy of ferrimagnetic CoFe2O4 thin films on Sc2O3/Si(111)

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.Ferrimagnetic spinel CoFe2O4 (CFO) films are integrated with Si(111) using Sc2O3 buffer layers. The huge lattice mismatch (17%) between CFO and Sc2O3 is accommodated by domain matching, and CFO grows epitaxially with (111) out-of-plane orientation and coexistence of A- and B-type in-plane crystal variants. CFO films have low roughness of 4 Å and saturation magnetization of about 300 emu/cm3. These properties make CFO films on Sc2O3-buffered Si(111) comparable to those grown on oxide single crystals and thus extend the possibilities of using spinel oxides in electronic devices

Integration of functional complex oxide nanomaterials on silicon

The combination of standard wafer-scale semiconductor processing with the properties of functional oxides opens up to innovative and more efficient devices with high value applications which can be produced at large scale. This review uncovers the main strategies that are successfully used to monolithically integrate functional complex oxide thin films and nanostructures on silicon: the chemical solution deposition approach (CSD) and the advanced physical vapor deposition techniques such as oxide molecular beam epitaxy (MBE). Special emphasis will be placed on complex oxide nanostructures epitaxially grown on silicon using the combination of CSD and MBE. Several examples will be presented, with a particular stress on the control of interfaces and crystallization mechanisms on epitaxial perovskite oxide thin films, nanostructured quartz thin films, and octahedral molecular sieve nanowires. This review enlightens on the potential of complex oxide nanostructures and the combination of both chemical and physical elaboration techniques for novel oxide-based integrated devicesAC acknowledges the financial support from 1D-RENOX project (Cellule Energie INSIS-CNRS). J.M.V.-F. also acknowledges MINECO for support with a Ph.D. grant of the FPI program. We thank David Montero and L. Picas for technical support. We also thank P. Regreny, C. Botella, J.B. Goure for technical assistance on the Nanolyon technological platform. We acknowledge MICINN (MAT2008-01022 MAT2011-28874-c02-01 and MAT2012-35324), Consolider NANOSELECT (CSD2007-00041), Generalitat de Catalunya (2009 SGR 770 and Xarmae), and EU (HIPERCHEM, NMP4-CT2005-516858) projects. The HAADF-STEM microscopy work was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. This research was supported by the European Research Council (ERC StG-2DTHERMS), Ministerio de Economía y Competitividad of Spain (MAT2013-44673-R) and EU funding Project “TIPS” Thermally Integrated Smart Photonics Systems Ref: 644453 call H2020-ICT-2014-1S

Giant tuning of electronic and thermoelectric properties by epitaxial strain in p-type Sr-doped LaCrO3 transparent thin films

The impact of epitaxial strain on the structural, electronic, and thermoelectric properties of p-type transparent Sr-doped LaCrO3 thin films has been investigated. For this purpose, high-quality fully-strained La0.75Sr0.25CrO3 (LSCO) epitaxial thin films were grown by molecular beam epitaxy on three different (pseudo)cubic (001)-oriented perovskite-oxide substrates: LaAlO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, and DyScO3. The lattice mismatch between the LSCO films and the substrates induces in-plane strain ranging from -2.06% (compressive) to +1.75% (tensile). The electric conductivity can be controlled over two orders of magnitude, σ ranging from ~0.5 S cm-1 (tensile strain) to 35 S cm-1 (compressive strain). Consistently, the Seebeck coefficient S can be finely tuned by a factor of almost two from ~127 μV K-1 (compressive strain) to 208 μV K-1 (tensile strain). Interestingly, we show that the thermoelectric power factor (PF = S2 σ) can consequently be tuned by almost two orders of magnitude. The compressive strain yields a remarkable enhancement by a factor of three for 2% compressive strain with respect to almost relaxed films. These results demonstrate that epitaxial strain is a powerful lever to control the electric properties of LSCO and enhance its thermoelectric properties, which is of high interest for various devices and key applications such as thermal energy harvesters, coolers, transparent conductors, photo-catalyzers and spintronic memories.Financial support from the European Commission through the project TIPS (H2020-ICT-02-2014-1-644453), the French national research agency (ANR) through the projects MITO (ANR-17-CE05-0018), LILIT (ANR-16-CE24-0022), DIAMWAFEL (ANR-15-CE08-0034-02), the CNRS through the MITI interdisciplinary programs (project NOTE), IDEX Lyon-St-Etienne through the project IPPON, the Spanish Ministerio de Ciencia e Innovación, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV2015-0496) and the MAT2017-85232-R (AEI/FEDER, EU), PID2019-107727RB-I00 (AEI/FEDER, EU), and from Generalitat de Catalunya (2017 SGR 1377) is acknowledged. The China Scholarship Council (CSC) is acknowledged for the grant of Dong Han. Ignasi Fina acknowledges Ramón y Cajal contract RYC-2017-22531. Seebeck measurements at ILM were made within the ILMTech transport platform. The authors are also grateful to Jean-Baptiste Goure, Philippe Regreny, Aziz Benamrouche, and Bernat Bozzo for their technical support and the reviewers for their valuable and constructive comments that have improved the quality of the manuscript.Peer reviewe

An innovative therapeutic educational program to support older drivers with cognitive disorders: Description of a randomized controlled trial study protocol

Older drivers face the prospect of having to adjust their driving habits because of health problems, which can include neurocognitive disorders. Self-awareness of driving difficulties and the interaction between individual with neurocognitive disorders and natural caregiver seem to be important levers for the implementation of adaptation strategies and for the subsequent voluntary cessation of driving when the cognitive disorders become too severe. This study aims to evaluate an educational program for patient/natural caregiver dyads who wish to implement self-regulation strategies in driving activity, and to improve self-awareness of driving ability. The ACCOMPAGNE program is based on seven group workshops, which target the dyad. The workshops deal with the impact of cognitive, sensory and iatrogenic disorders on driving. They tackle questions about responsibility, and about autonomy and social life. They also provide alternative solutions aimed at maintaining outward-looking activities even if driving is reduced or stopped. A randomized controlled trial is planned to evaluate the effectiveness of the program 2 months and 6 months after inclusion, and to compare this to the effectiveness of conventional approaches. The main outcome of this trial (i.e., the implementation of self-regulated driving strategies), will be measured based on scores on the “Current Self-Regulatory Practices” subscale of the Driver Perception and Practices Questionnaire. The Driving Habits Questionnaire will be used to measure secondary outcomes (indicators of driving changes; indicators of changes in mood, quality of life and caregiver burden; and self-awareness of driving abilities). Indicators will be collected for both patients and natural caregivers. This cognitive, social and psychological program should allow older individuals with cognitive disorders to drive more safely, and help to maintain the quality of life and mood of both patient and natural caregiver despite driving limitations. The patient's care path would be optimized, as he/she would become an actor in the process of giving up driving, which will, most certainly, be needed at some point in the progress of neurocognitive disorders. This process ranges from becoming aware of driving difficulties, to implementing self-regulation strategies, through to complete cessation of driving when necessary.Clinical trial registration numberNCT04493957

Front Psychiatry

OBJECTIVE: During the COVID-19 pandemic, older people and patients with psychiatric disorders had an increased risk of being isolated. The French National Authority for Health has recommended a reinforced follow-up of these patients. Cross-sectional studies reported an increased risk of developing anxiety and depression during pandemic. The aim of our study was to identify factors associated with higher anxiety during the pandemic in older patients with psychiatric disorders. METHODS: STERACOVID is a multicenter cohort study with 117 patients followed-up by phone in two French geriatric psychiatry units. In this work, we used cross-sectional data from a prospective follow-up conducted between January and May 2021. RESULTS: We found that coping strategies, personality, and living conditions were associated with general anxiety (GA) level during the pandemic period. Higher GA was associated with less positive thinking coping strategy, more avoidance strategies, a lower level of extraversion, a higher level of neuroticism, more time spent watching the news, a higher feeling of loneliness, and a lack of physical contact. FINDINGS: Our study identified factors associated with a poorer experience of pandemic crisis. Special attention should be paid to patients with a high level of neuroticism and a high feeling of loneliness. Support could aim to help patients use more functional strategies: reducing avoidance strategies and increasing positive thinking. Finally, reducing time watching news could also be an interesting prevention perspective. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov, identifier NCT04760795

Vaccine breakthrough hypoxemic COVID-19 pneumonia in patients with auto-Abs neutralizing type I IFNs

Life-threatening `breakthrough' cases of critical COVID-19 are attributed to poor or waning antibody response to the SARS- CoV-2 vaccine in individuals already at risk. Pre-existing autoantibodies (auto-Abs) neutralizing type I IFNs underlie at least 15% of critical COVID-19 pneumonia cases in unvaccinated individuals; however, their contribution to hypoxemic breakthrough cases in vaccinated people remains unknown. Here, we studied a cohort of 48 individuals ( age 20-86 years) who received 2 doses of an mRNA vaccine and developed a breakthrough infection with hypoxemic COVID-19 pneumonia 2 weeks to 4 months later. Antibody levels to the vaccine, neutralization of the virus, and auto- Abs to type I IFNs were measured in the plasma. Forty-two individuals had no known deficiency of B cell immunity and a normal antibody response to the vaccine. Among them, ten (24%) had auto-Abs neutralizing type I IFNs (aged 43-86 years). Eight of these ten patients had auto-Abs neutralizing both IFN-a2 and IFN-., while two neutralized IFN-omega only. No patient neutralized IFN-ss. Seven neutralized 10 ng/mL of type I IFNs, and three 100 pg/mL only. Seven patients neutralized SARS-CoV-2 D614G and the Delta variant (B.1.617.2) efficiently, while one patient neutralized Delta slightly less efficiently. Two of the three patients neutralizing only 100 pg/mL of type I IFNs neutralized both D61G and Delta less efficiently. Despite two mRNA vaccine inoculations and the presence of circulating antibodies capable of neutralizing SARS-CoV-2, auto-Abs neutralizing type I IFNs may underlie a significant proportion of hypoxemic COVID-19 pneumonia cases, highlighting the importance of this particularly vulnerable population

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men