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Search Results: 1 - 10 of 208473 matches for " L. Giot "
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Investigating ferromagnetism and charge order in Bi1-xSrxMnO3 (x﹤0.3) ceramic oxides
García-Mu?oz, J. L.,Frontera, C.,Hervieu, M.,Giot, M.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2006,
Abstract: The possible coexistence of ferromagnetism and charge/orbital order in Bi3/4Sr1/4MnO3 has been investigated. The manganite Bi0.75Sr0.25MnO3, with commensurate charge balance, undergoes an electronic transition at TCO~600 K that produces a longrange modulation with double periodicity along a and c axis, and unusual anisotropic evolution of the lattice parameters. The previously proposed ferromagnetic properties of this new ordered phase were studied by magnetometry and diffraction techniques. In zero field the magnetic structure is globally antiferromagnetic, ruling out the apparition of spontaneous ferromagnetism. However, the application of magnetic fields produces a continuous progressive canting of the moments, inducing a ferromagnetic phase even for relatively small fields (H 1 T). Application of pulsed high fields produces a remarkable and reversible spin polarization (under 30 T, the ferromagnetic moment is ~3 μB/Mn, without any sign of charge order melting). The coexistence of ferromagnetism and charge order at low and very-high fields is a remarkable property of this system. Se ha estudiado la coexistencia de ferromagnetismo y orden de carga en óxidos cerámicos del tipo Bi1-xSrxMnO3 con x 0.5. Bi0.75Sr0.25MnO3 (x =2/8) presenta una transición estructural y electrónica a TCO~600 K que da lugar a nueva fase de orden de carga con simetría promedio Ibmm y una supercelda que dobla los ejes a y c . BiMnO3 (multiferroico) es ferromagnético por debajo de TC=105 K. Se han utilizado técnicas magnéticas y de difracción para investigar si la persistencia de ferromagnetismo en las medidas magnéticas hasta x≤0.4 puede ser el resultado de una dilución progresiva de la fase ferromagnètica del compuesto monoclínico puro. La estructura magnética en Bi0.75Sr0.25MnO3 es globalmente antiferromagnètica, descartando la aparición de ferromagnetismo espontáneo. Sin embargo, la respuesta al campo magnético es inusual: se observa un canting continuado y progresivo de los momentos desde campos muy peque os hasta la saturación ferromagnètica, sin signos de la fusión del orden de carga con campos de hasta 30 Teslas. La coexistencia de ferromagnetismo y orden de carga es una propiedad remarcable de estos óxidos.
Reactor Simulation for Antineutrino Experiments using DRAGON and MURE
C. L. Jones,A. Bernstein,J. M. Conrad,Z. Djurcic,M. Fallot,L. Giot,G. Keefer,A. Onillon,L. Winslow
Physics , 2011, DOI: 10.1103/PhysRevD.86.012001
Abstract: Rising interest in nuclear reactors as a source of antineutrinos for experiments motivates validated, fast, and accessible simulations to predict reactor fission rates. Here we present results from the DRAGON and MURE simulation codes and compare them to other industry standards for reactor core modeling. We use published data from the Takahama-3 reactor to evaluate the quality of these simulations against the independently measured fuel isotopic composition. The propagation of the uncertainty in the reactor operating parameters to the resulting antineutrino flux predictions is also discussed.
Agarose Gel Electrophoresis - Applications in Clinical Chemistry
Jean-Francois Giot
Journal of Medical Biochemistry , 2010, DOI: 10.2478/v10011-009-0033-8
Abstract: Agarose gel electrophoresis is a well established technique routinely used in clinical laboratories for screening protein abnormalities in various biological fluids (serum, urine, CSF). It is based on the principles of zone electrophoresis. Electrophoretograms are evaluated visually for the presence of quantitatively or qualitatively abnormal protein bands. The technique is used for electrophoresis of serum, urine, CSF proteins, enzymes (ALP, LDH and CK), lipoproteins and hemoglobin. Serum protein electrophoresis (SPE) is a very commonly used analytical method in clinical chemistry. Changes in the relative concentration of fractions allow easy recognition of pathological disorders associated with nephrotic syndrome, inflammatory reaction and hepatic diseases. SPE is a screening test for detecting the M component (MC). Immunofixation (IFE) with use of specific antisera allows detection of the type of MC. SPE is also a method for the quantification of MC and monitoring of disease that is essential for clinical evaluation and follow-up of patients with plasma cell disorders.
Genetic Programming for Multibiometrics
Romain Giot,Christophe Rosenberger
Computer Science , 2012, DOI: 10.1016/j.eswa.2011.08.066
Abstract: Biometric systems suffer from some drawbacks: a biometric system can provide in general good performances except with some individuals as its performance depends highly on the quality of the capture. One solution to solve some of these problems is to use multibiometrics where different biometric systems are combined together (multiple captures of the same biometric modality, multiple feature extraction algorithms, multiple biometric modalities...). In this paper, we are interested in score level fusion functions application (i.e., we use a multibiometric authentication scheme which accept or deny the claimant for using an application). In the state of the art, the weighted sum of scores (which is a linear classifier) and the use of an SVM (which is a non linear classifier) provided by different biometric systems provide one of the best performances. We present a new method based on the use of genetic programming giving similar or better performances (depending on the complexity of the database). We derive a score fusion function by assembling some classical primitives functions (+, *, -, ...). We have validated the proposed method on three significant biometric benchmark datasets from the state of the art.
A Drosophila protein-interaction map centered on cell-cycle regulators
Clement A Stanyon, Guozhen Liu, Bernardo A Mangiola, Nishi Patel, Loic Giot, Bing Kuang, Huamei Zhang, Jinhui Zhong, Russell L Finley
Genome Biology , 2004, DOI: 10.1186/gb-2004-5-12-r96
Abstract: To complement the Gal4-based interaction data, we used the same set of Drosophila open reading frames to construct arrays for a LexA-based two-hybrid system. We screened the arrays using a novel pooled mating approach, initially focusing on proteins related to cell-cycle regulators. We detected 1,814 reproducible interactions among 488 proteins. The map includes a large number of novel interactions with potential biological significance. Informative regions of the map could be highlighted by searching for paralogous interactions and by clustering proteins on the basis of their interaction profiles. Surprisingly, only 28 interactions were found in common between the LexA- and Gal4-based screens, even though they had similar rates of true positives.The substantial number of new interactions discovered here supports the conclusion that previous interaction mapping studies were far from complete and that many more interactions remain to be found. Our results indicate that different two-hybrid systems and screening approaches applied to the same proteome can generate more comprehensive datasets with more cross-validated interactions. The cell-cycle map provides a guide for further defining important regulatory networks in Drosophila and other organisms.Protein-protein interactions have an essential role in a wide variety of biological processes. A wealth of data has emerged to show that most proteins function within networks of interacting proteins, and that many of these networks have been conserved throughout evolution. Although some of these networks constitute stable multi-protein complexes while others are more dynamic, they are all built from specific binary interactions between individual proteins. Maps depicting the possible binary interactions among proteins can therefore provide clues not only about the functions of individual proteins but also about the structure and function of entire protein networks and biological systems.One of the most powerful technologi
Chronic hepatitis C infection in a patient with bone marrow hypoplasia
S Bethlen, K Chandrikakumari, L de Leval, JB Giot, D Mukeba, P Leonard, F Frippiat, C Meuris, J Delwaide, M Moutschen
World Journal of Gastroenterology , 2008,
Abstract: Chronic hepatitis C virus (HCV) infection is associated with multifarious extra-hepatic manifestations; the most described and discussed being mixed cryoglobulinemia which is strongly related to B-cell lymphoproliferative disorders (LPDs). We present a case of chronic HCV infection and mixed cryoglobulinemia, with minimal liver involvement. The case is a 53-year-old patient who was diagnosed as having bone marrow hypoplasia at the age of three. She received several blood transfusions to normalize her haemoglobin. At the age of 31, she was diagnosed with rheumatoid arthritis on account of her diffuse joint pain and inflammation, elevated rheumatoid factor (RF) and Raynaud’s phenomenon. Twenty years later, monoclonal gammopathy of IgG Lambda (one year later, changed to IgM Kappa) was detected during a routine examination. A bone marrow biopsy showed hypoplasia, Kappa positive B-lymphocytes and low-grade malignant lymphoma cells. PCR of the bone marrow aspirate was not contributory. No treatment was initiated owing to her poor bone marrow function and she is under regular follow-up.
One-dimensional magnetic fluctuations in the spin-2 triangular lattice α-NaMnO2
C. Stock,L. C. Chapon,O. Adamopoulos,A. Lappas,M. Giot,J. W. Taylor,M. A. Green,C. M. Brown,P. G. Radaelli
Physics , 2009, DOI: 10.1103/PhysRevLett.103.077202
Abstract: The S=2 anisotropic triangular lattice alpha-NaMnO2 is studied by neutron inelastic scattering. Antiferromagnetic order occurs at T ~ 45 K with opening of a spin gap. The spectral weight of the magnetic dynamics above the gap (Delta ~ 7.5 meV) has been analysed by the single-mode approximation. Excellent agreement with the experiment is achieved when a dominant exchange interaction (|J|/k_B ~ 73 K), along the monoclinic b-axis and a sizeable easy-axis magnetic anisotropy (|D|/k_B ~ 3 K) are considered. Despite earlier suggestions for two-dimensional spin interactions, the dynamics illustrate strongly coupled antiferromagnetic S=2 chains and cancellation of the interchain exchange due to the lattice topology. alpha-NaMnO2 therefore represents a model system where the geometric frustration is resolved through the lowering of the dimensionality of the spin interactions.
Improved Predictions of Reactor Antineutrino Spectra
Th. A. Mueller,D. Lhuillier,M. Fallot,A. Letourneau,S. Cormon,M. Fechner,L. Giot,T. Lasserre,J. Martino,G. Mention,A. Porta,F. Yermia
Physics , 2011, DOI: 10.1103/PhysRevC.83.054615
Abstract: We report new calculations of reactor antineutrino spectra including the latest information from nuclear databases and a detailed error budget. The first part of this work is the so-called ab initio approach where the total antineutrino spectrum is built from the sum of all beta-branches of all fission products predicted by an evolution code. Systematic effects and missing information in nuclear databases lead to final relative uncertainties in the 10 to 20% range. A prediction of the antineutrino spectrum associated with the fission of 238U is given based on this ab initio method. For the dominant isotopes 235U and 239Pu, we developed a more accurate approach combining information from nuclear databases and reference electron spectra associated with the fission of 235U, 239Pu and 241Pu, measured at ILL in the 80's. We show how the anchor point of the measured total beta-spectra can be used to suppress the uncertainty in nuclear databases while taking advantage of all the information they contain. We provide new reference antineutrino spectra for 235U, 239Pu and 241Pu isotopes in the 2-8 MeV range. While the shapes of the spectra and their uncertainties are comparable to that of the previous analysis of the ILL data, the normalization is shifted by about +3% on average. In the perspective of the re-analysis of past experiments and direct use of these results by upcoming oscillation experiments, we discuss the various sources of errors and their correlations as well as the corrections induced by off equilibrium effects.
Performance Evaluation of Biometric Template Update
Romain Giot,Christophe Rosenberger,Bernadette Dorizzi
Computer Science , 2012,
Abstract: Template update allows to modify the biometric reference of a user while he uses the biometric system. With such kind of mechanism we expect the biometric system uses always an up to date representation of the user, by capturing his intra-class (temporary or permanent) variability. Although several studies exist in the literature, there is no commonly adopted evaluation scheme. This does not ease the comparison of the different systems of the literature. In this paper, we show that using different evaluation procedures can lead in different, and contradictory, interpretations of the results. We use a keystroke dynamics (which is a modality suffering of template ageing quickly) template update system on a dataset consisting of height different sessions to illustrate this point. Even if we do not answer to this problematic, it shows that it is necessary to normalize the template update evaluation procedures.
Local Water Diffusion Phenomenon Clustering From High Angular Resolution Diffusion Imaging (HARDI)
Romain Giot,Christophe Charrier,Maxime Descoteaux
Computer Science , 2012,
Abstract: The understanding of neurodegenerative diseases undoubtedly passes through the study of human brain white matter fiber tracts. To date, diffusion magnetic resonance imaging (dMRI) is the unique technique to obtain information about the neural architecture of the human brain, thus permitting the study of white matter connections and their integrity. However, a remaining challenge of the dMRI community is to better characterize complex fiber crossing configurations, where diffusion tensor imaging (DTI) is limited but high angular resolution diffusion imaging (HARDI) now brings solutions. This paper investigates the development of both identification and classification process of the local water diffusion phenomenon based on HARDI data to automatically detect imaging voxels where there are single and crossing fiber bundle populations. The technique is based on knowledge extraction processes and is validated on a dMRI phantom dataset with ground truth.
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