Browsing Complete repository Arts & humanities   Archaeology   Art & art history   Classical & oriental studies   History   Languages & linguistics   Literature   Performing arts   Philosophy & ethics   Religion & theology   Multidisciplinary, general & others Business & economic sciences   Accounting & auditing   Production, distribution & supply chain management   Finance   General management & organizational theory   Human resources management   Management information systems   Marketing   Strategy & innovation   Quantitative methods in economics & management   General economics & history of economic thought   International economics   Macroeconomics & monetary economics   Microeconomics   Economic systems & public economics   Social economics   Special economic topics (health, labor, transportation…)   Multidisciplinary, general & others Engineering, computing & technology   Aerospace & aeronautics engineering   Architecture   Chemical engineering   Civil engineering   Computer science   Electrical & electronics engineering   Energy   Geological, petroleum & mining engineering   Materials science & engineering   Mechanical engineering   Multidisciplinary, general & others Human health sciences   Alternative medicine   Anesthesia & intensive care   Cardiovascular & respiratory systems   Dentistry & oral medicine   Dermatology   Endocrinology, metabolism & nutrition   Forensic medicine   Gastroenterology & hepatology   General & internal medicine   Geriatrics   Hematology   Immunology & infectious disease   Laboratory medicine & medical technology   Neurology   Oncology   Ophthalmology   Orthopedics, rehabilitation & sports medicine   Otolaryngology   Pediatrics   Pharmacy, pharmacology & toxicology   Psychiatry   Public health, health care sciences & services   Radiology, nuclear medicine & imaging   Reproductive medicine (gynecology, andrology, obstetrics)   Rheumatology   Surgery   Urology & nephrology   Multidisciplinary, general & others Law, criminology & political science   Civil law   Criminal law & procedure   Criminology   Economic & commercial law   European & international law   Judicial law   Metalaw, Roman law, history of law & comparative law   Political science, public administration & international relations   Public law   Social law   Tax law   Multidisciplinary, general & others Life sciences   Agriculture & agronomy   Anatomy (cytology, histology, embryology...) & physiology   Animal production & animal husbandry   Aquatic sciences & oceanology   Biochemistry, biophysics & molecular biology   Biotechnology   Entomology & pest control   Environmental sciences & ecology   Food science   Genetics & genetic processes   Microbiology   Phytobiology (plant sciences, forestry, mycology...)   Veterinary medicine & animal health   Zoology   Multidisciplinary, general & others Physical, chemical, mathematical & earth Sciences   Chemistry   Earth sciences & physical geography   Mathematics   Physics   Space science, astronomy & astrophysics   Multidisciplinary, general & others Social & behavioral sciences, psychology   Animal psychology, ethology & psychobiology   Anthropology   Communication & mass media   Education & instruction   Human geography & demography   Library & information sciences   Neurosciences & behavior   Regional & inter-regional studies   Social work & social policy   Sociology & social sciences   Social, industrial & organizational psychology   Theoretical & cognitive psychology   Treatment & clinical psychology   Multidisciplinary, general & others      by title 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z or enter first few letters:    OK Showing results 85681 to 85700 of 132024     4280 4281 4282 4283 4284 4285 4286 4287 4288 4289 4290     Non-visual effects of light on melatonin, alertness and cognitive performance: can blue-enriched light keep us alert?Chellappa, Sarah Laxhmi ; Steiner, Roland; Blattner, Peter et alin PLoS ONE (2011), 6(1), 16429BACKGROUND: Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system, whose spectral relevance is highest in the short-wavelength range. Here we ... [more ▼]BACKGROUND: Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system, whose spectral relevance is highest in the short-wavelength range. Here we investigated if commercially available compact fluorescent lamps with different colour temperatures can impact on alertness and cognitive performance. METHODS: Sixteen healthy young men were studied in a balanced cross-over design with light exposure of 3 different light settings (compact fluorescent lamps with light of 40 lux at 6500K and at 2500K and incandescent lamps of 40 lux at 3000K) during 2 h in the evening. RESULTS: Exposure to light at 6500K induced greater melatonin suppression, together with enhanced subjective alertness, well-being and visual comfort. With respect to cognitive performance, light at 6500K led to significantly faster reaction times in tasks associated with sustained attention (Psychomotor Vigilance and GO/NOGO Task), but not in tasks associated with executive function (Paced Visual Serial Addition Task). This cognitive improvement was strongly related with attenuated salivary melatonin levels, particularly for the light condition at 6500K. CONCLUSIONS: Our findings suggest that the sensitivity of the human alerting and cognitive response to polychromatic light at levels as low as 40 lux, is blue-shifted relative to the three-cone visual photopic system. Thus, the selection of commercially available compact fluorescent lights with different colour temperatures significantly impacts on circadian physiology and cognitive performance at home and in the workplace. [less ▲]Detailed reference viewed: 16 (1 ULg) Non-visual responses to light in brain structures involved in alertness regulation and cognition - a fMRI approach. Non-circadian effects of light on sleep, alertness and cognition symposium.Vandewalle, Gilles Conference (2009, June)Detailed reference viewed: 11 (1 ULg) Nonadiabatic observables in main sequence delta Scuti starsMoya, A.; Garrido, R.; Dupret, Marc-Antoine in IAU Colloq. 193: Variable Stars in the Local Group (2004, May 01)Using a theoretical nonadiabatic pulsation model, phase differences and amplitude ratios between the relative effective temperature variation and the relative radial displacement have been calculated ... [more ▼]Using a theoretical nonadiabatic pulsation model, phase differences and amplitude ratios between the relative effective temperature variation and the relative radial displacement have been calculated. These quantities, when compared with photometric observations in different colors, provide an efficient instrument for mode identification, the first step to understand the internal structure of the stars. The theoretical results presented in this paper show a dependence for delta Scuti stars on the mixing length parameter alpha used to treat the convection using the standard Mixing Length Theory. The nonadiabatic pulsational code developed here includes the pulsation atmosphere interaction as described by Dupret et al. (2002). The equilibrium models are provided by the CESAM evolutionary code, where a complete reconstruction of non-grey atmospheres (Kurucz models) is included. [less ▲]Detailed reference viewed: 13 (1 ULg) NONADIABATIC UNIMOLECULAR REACTIONS .2. ISOTOPE EFFECTS ON THE KINETIC-ENERGY RELEASERemacle, Françoise ; Dehareng, Dominique ; Lorquet, Jean-Claude in Journal of Physical Chemistry (1988), 92(16), 4784-4787This paper investigates the isotope effect that occurs when XOCO+ ions dissociate into XOC+ + 0 on a microsecond time scale (X = H or D). The reaction mechanism involves an electronic spin-forbidden ... [more ▼]This paper investigates the isotope effect that occurs when XOCO+ ions dissociate into XOC+ + 0 on a microsecond time scale (X = H or D). The reaction mechanism involves an electronic spin-forbidden predissociation between a stable singlet state and a repulsive triplet. Application of the statistical equations developed in the previous paper shows that, at a given energy, the predissociation rate constant is consistently smaller for DOCO’ than for HOCO+. Therefore, the internal energy necessary to bring about dissociation of the hydrogenated compound with a given rate constant is always lower than that of the deuteriated compound by a quantity AE* which is found to be equal to ca. 0.050 eV when k = lo6 s-l and to ca 0.020 eV for k = lo3 s-1. As a result, the excess energy which is released as kinetic energy carried by the fragments is substantially greater for the deuteriated than for the hydrogenated compound. This accounts for experiments which indicate that, in the microsecond time scale, DOCO’ gives rise to a dished metastable peak whereas the corresponding signal for HOCO’ is simply Gaussian. [less ▲]Detailed reference viewed: 26 (5 ULg) Nonadiabatic Unimolecular Reactions of Polyatomic MoleculesDesouter-Lecomte, Michèle ; Dehareng, Dominique ; Leyh-Nihant, Brigitte et alin Journal of Physical Chemistry (1985), 89The nonadiabatic couplings which arise when two potential energy surfaces of a polyatomic molecule get close in energy can be classified as follows: (A) avoided crossings, (B) genuine intersections (Jahn ... [more ▼]The nonadiabatic couplings which arise when two potential energy surfaces of a polyatomic molecule get close in energy can be classified as follows: (A) avoided crossings, (B) genuine intersections (Jahn-Teller and conical), (C) glancing intersections (Renner-Teller interactions). The characteristics of the potential energy surfaces in the adiabatic and diabatic representations are discussed for each case. The three coupling cases differ in the structure of the Hamiltonian matrix. When the latter is written in the diabatic representation, it is meaningful to retain the leading term only in its power series expansion. This gives rise to a so-called minimum-order model which is found to be surprisingly accurate (at least in a restricted zone of nuclear coordinates) when compared to the results of ab initio calculations. The characteristic features of each coupling case can only be understood in a two-dimensional configuration space, Le., when two nuclear degrees of freedom, often with different symmetry properties, are explicitly considered. A simple expression of the nonadiabatic transition probability between two electronic states can be worked out in the framework of the minimum-order models. Two-dimensional extensions of the Landau-Zener formula are obtained, which can be used to study the consequences of the anisotropic properties of the coupling. In the case of avoided crossings, only nuclear trajectories having a well-defined direction are able to bring about surface hopping, wheras there exists two active degrees of freedom for conical intersections. Hence, nonadiabatic processes which are controlled by genuine intersections are expected to take place faster than those controlled by avoided crossings. [less ▲]Detailed reference viewed: 43 (3 ULg) Nonadiabatic unimolecular reactions. III. Dissociation mechanisms of methylnitrite and deuterated methylnitrite ionsLeyh-Nihant, Brigitte ; Lorquet, Jean-Claude in Journal of Chemical Physics (1988), 88(9), 5606-5619At low energies, methylnitrite ions dissociate via two channels giving rise to CH3O + NO+ or to [CH3O+] + NO fragments. Peculiar characteristics have been detected in the dissociation of energy-selected ... [more ▼]At low energies, methylnitrite ions dissociate via two channels giving rise to CH3O + NO+ or to [CH3O+] + NO fragments. Peculiar characteristics have been detected in the dissociation of energy-selected parent ions, viz., remarkably low rate constants, one of which is found to remain insensitive to an increase of the internal energy, and large isotope effect. These peculiarities are accounted for by a statistical, nonadiabatic model. Ab initio calculations, confirmed by multipolar expansions reveal that the potential energy curves which correlate to these two dissociation asymptotes cross. The crossing takes place at a large value along the reaction coordinate R, indicating a long-range interaction. Production of the CH3O + NO+ fragments results from a simple bond cleavage taking place on a single diabatic surface. On the other hand, production of [CH3O+] + NO fragments is brought about by a transition from one diabatic surface to the other. It leads to deformed methoxy ions which immediately rearrange to the much more stable H2COH + structure. The nonadiabatic rate constant has been calculated by a statistical method. The contribution of each channel is weighted by a transmission coefficient which is equal to the nonadiabatic transition probability. Implementation of this statistical treatment requires partitioning the set of degrees of freedom as follows: {R, y, d, v}. It is necessary to withdraw the isomerization mode y from the statistical treatment, because the equilibrium positions along this coordinate are very different in each electronic state. Physically, this means that the reaction involves tunneling from one surface to the other along the displaced degree of freedom y. The large isotope effect has a double origin: part of it (a factor of ∼9) results from tunneling along γ; the remainder (an additional factor of 3) comes from the usual RRKM-like effect on the densities of states. The degrees d constitute a set of four low-energy bending modes which form a sink for the internal energy. The nonadiabatic transition probability is determined by the off-diagonal matrix element V12(Rc). Effective potential energy curves have been calculated by extending the Quack and Troe method to nonadiabatic reactions. It turns out that the excitation of the set d leads to a decrease of V12(Rc) and hence to a decrease of the nonadiabatic transmission coefficient. This accounts for the weak dependence of the rate constants kCH3O+ and kCD3O+ vs the energy (at least above a certain energy threshold). © 1988 American Institute of Physics. [less ▲]Detailed reference viewed: 15 (0 ULg) Nonalcoholic steatohepatitis and insulin resistance: interface between gastroenterologists and endocrinologists.Scheen, André ; Luyckx, Françoise in Acta Clinica Belgica (2003), 58(2), 81-91Nonalcoholic steatohepatitis (NASH), along with other forms of nonalcoholic fatty liver disease, is an increasingly common clinico-pathological syndrome. It is frequently associated with obesity ... [more ▼]Nonalcoholic steatohepatitis (NASH), along with other forms of nonalcoholic fatty liver disease, is an increasingly common clinico-pathological syndrome. It is frequently associated with obesity, especially visceral fat, and type 2 diabetes, and is intimately related to markers of the insulin resistance syndrome. Both the prevalence and the severity of liver steatosis are related to body mass index, waist circumference, hyperinsulinaemia, hypertriglyceridemia and impaired glucose tolerance. The pathophysiology of NASH involves two steps: 1) insulin resistance, which causes steatosis; 2) and oxidative stress, which produces lipid peroxidation and activates inflammatory cytokines. The identification of subjects who may progress from fatty liver to NASH, and from NASH to fibrosis/cirrhosis is an important clinical challenge as well as the finding of appropriate therapy that could prevent such deleterious process. Substantial weight loss is accompanied by a marked attenuation of insulin resistance and related metabolic syndrome and, concomitantly, by an important regression of liver steatosis in most patients, although mild inflammation may be detected in some subjects. Thus, NASH may be considered as another disease of affluence, as is the insulin resistance syndrome and perhaps being part of it. [less ▲]Detailed reference viewed: 97 (1 ULg) Nonaqueous capillary electrophoresis method for the enantiomeric purity determination of S-timolol using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin: validation using the accuracy profile strategy and estimation of uncertainty.Marini Djang'Eing'A, Roland ; Servais, Anne-Catherine ; Rozet, Eric et alin Journal of Chromatography. A (2006), 1120(1-2), 102-11Nonaqueous capillary electrophoresis (NACE) was successfully applied to the enantiomeric purity determination of S-timolol maleate using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-beta-CD ... [more ▼]Nonaqueous capillary electrophoresis (NACE) was successfully applied to the enantiomeric purity determination of S-timolol maleate using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-beta-CD) as chiral selector. With a background electrolyte made up of a methanolic solution of 0.75 M formic acid, 30 mM potassium camphorsulfonate and containing 30 mM HDMS-beta-CD, the determination of 0.1% of R-timolol in S-timolol could be performed with an enantiomeric resolution of 8.5. Pyridoxine was selected as internal standard. The NACE method was then fully validated by applying a novel strategy using accuracy profiles. It is based on beta-expectation tolerance intervals for the total measurement error which includes trueness and intermediate precision. The uncertainty of measurements derived from beta-expectation tolerance intervals was estimated at each concentration level of the validation standards. To confirm the suitability of the developed and validated method, several real samples of S-timolol maleate containing R-timolol maleate at different concentrations were analysed and the results were compared to those obtained by liquid chromatography. [less ▲]Detailed reference viewed: 63 (15 ULg) Nonaqueous capillary electrophoretic behavior of 2-aryl propionic acids in the presence of an achiral ionic liquid - A chemometric approachFrancois, Yannis; Varenne, Anne; Juillerat, Emilie et alin Journal of Chromatography. A (2007), 1138(1-2), 268-275Ionic liquids (ILs) appear really attractive as electrolyte additives in nonaqueous capillary electrophoresis (NACE). These salts may offer new possibilities of interactions to modulate analyte effective ... [more ▼]Ionic liquids (ILs) appear really attractive as electrolyte additives in nonaqueous capillary electrophoresis (NACE). These salts may offer new possibilities of interactions to modulate analyte effective mobilities. The presence of 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIM NTf2) in acetonitrile/alcohol background electrolytes (BGEs) was investigated in this work. The aim of this study was to elucidate the influence of the IL concentration on the electrophoretic behavior of four arylpropionic acids and to identify the interactions between the analytes and the 1L cation. The influence on mobility of the IL concentration, the nature and the proportion of the organic solvents, and the concentration of the ionic components of the BGE was first studied by a univariate approach. A four-factor D-optimal experimental design was then applied to provide a deeper insight into analyte interaction with IL cation present both free in BGE and adsorbed onto the capillary wall. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]Detailed reference viewed: 52 (1 ULg) Nonaqueous electrokinetic chromatography-electrospray ionization mass spectrometry using anionic cyclodextrinsMol, Roelof; Servais, Anne-Catherine ; Fillet, Marianne et alin Journal of Chromatography. A (2007), 1159(1-2), 51-57The set-up of an on-line method for coupling nonaqueous electrokinetic chromatography (NAEKC) and electrospray ionization mass spectrometry (ESI-MS) is presented. It allows the use of the single-isomer ... [more ▼]The set-up of an on-line method for coupling nonaqueous electrokinetic chromatography (NAEKC) and electrospray ionization mass spectrometry (ESI-MS) is presented. It allows the use of the single-isomer derivative anionic cyclodextrins heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-beta-CD) and heptakis(2.3-di-O-acetyl-6-O-sulfo)-beta-cyclodextrin (HDAS-beta-CD) for chiral and achiral separations of positively charged analytes. The effect of the cyclodextrins (CDs) on the MS signal intensities of model compounds was studied. When a voltage is applied over the CE capillary, the overall mobility of the CDs is towards the inlet vial preventing CDs from entering the ion source. However, the sodium counter ions of the CDs still enter the ion source and appeared to cause ionization suppression. Nevertheless, significant analyte signals could still be detected with detection limits in the sub-mu g/ml. System parameters such as sheath liquid composition and flow rate, nebulizing gas pressure, capillary position in the sprayer and the drying gas flow and temperature were studied and optimized. The selection of a relatively low nebulizing gas pressure appeared to be important to achieve optimum sensitivity. The chiral selectivity of the NAEKC-ESI-MS system could be improved by addition of camphorsulfonate to the background electrolyte. Using mixtures of drugs and drug-related compounds, the NAEKC-ESI-MS system is shown to offer potential for (chiral) drug profiling. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]Detailed reference viewed: 34 (3 ULg) Nonbreathhold Gadolinium-enhanced MRA of the Renal Arteries with Partially Parallel 3D Time-resolved ImagingNCHIMI LONGANG, Alain ; BRISBOIS, Denis ; MATERNE, ROLAND et alPoster (2004)Detailed reference viewed: 18 (1 ULg) Noncanonical NF-kappaB Signaling Is Limited by Classical NF-kappaB Activity.Gray, Carolyn M.; Remouchamps, Caroline ; McCorkell, Kelly A. et alin Science signaling (2014), 7(311), 13Precise regulation of nuclear factor kappaB (NF-kappaB) signaling is crucial for normal immune responses, and defective NF-kappaB activity underlies a range of immunodeficiencies. NF-kappaB is activated ... [more ▼]Precise regulation of nuclear factor kappaB (NF-kappaB) signaling is crucial for normal immune responses, and defective NF-kappaB activity underlies a range of immunodeficiencies. NF-kappaB is activated through two signaling cascades: the classical and noncanonical pathways. The classical pathway requires inhibitor of kappaB kinase beta (IKKbeta) and NF-kappaB essential modulator (NEMO), and hypomorphic mutations in the gene encoding NEMO (ikbkg) lead to inherited immunodeficiencies, collectively termed NEMO-ID. Noncanonical NF-kappaB activation requires NF-kappaB-inducing kinase (NIK) and IKKalpha, but not NEMO. We found that noncanonical NF-kappaB was basally active in peripheral blood mononuclear cells from NEMO-ID patients and that noncanonical NF-kappaB signaling was similarly enhanced in cell lines lacking functional NEMO. NIK, which normally undergoes constitutive degradation, was aberrantly present in resting NEMO-deficient cells, and regulation of its abundance was rescued by reconstitution with full-length NEMO, but not a mutant NEMO protein unable to physically associate with IKKalpha or IKKbeta. Binding of NEMO to IKKalpha was not required for ligand-dependent stabilization of NIK or noncanonical NF-kappaB signaling. Rather, an intact and functional IKK complex was essential to suppress basal NIK activity in unstimulated cells. Despite interacting with IKKalpha and IKKbeta to form an IKK complex, NEMO mutants associated with immunodeficiency failed to rescue classical NF-kappaB signaling or reverse the accumulation of NIK. Together, these findings identify a crucial role for classical NF-kappaB activity in the suppression of basal noncanonical NF-kappaB signaling. [less ▲]Detailed reference viewed: 10 (1 ULg) The Noncatalytic Triad of Alpha-Amylases: A Novel Structural Motif Involved in Conformational StabilityMarx, J. C.; Poncin, J.; Simorre, J. P. et alin Proteins (2008), 70(2), 320-328Chloride-activated alpha-amylases contain a noncatalytic triad, independent of the glycosidic active site, perfectly mimicking the catalytic triad of serine-proteases and of other active serine hydrolytic ... [more ▼]Chloride-activated alpha-amylases contain a noncatalytic triad, independent of the glycosidic active site, perfectly mimicking the catalytic triad of serine-proteases and of other active serine hydrolytic enzymes. Mutagenesis of Glu, His, and Ser residues in various alpha-amylases shows that this pattern is a structural determinant of the enzyme conformation that cannot be altered without losing the intrinsic stability of the protein. (1)H-(15)N NMR spectra of a bacterial alpha-amylase reveal proton signals that are identical with the NMR signature of catalytic triads and especially a deshielded proton involving a protonated histidine and displaying properties similar to that of a low barrier hydrogen bond. It is proposed that the H-bond between His and Glu of the noncatalytic triad is an unusually strong interaction, responsible for the observed NMR signal and for the weak stability of the triad mutants. Furthermore, a stringent template-based search of the Protein Data Bank demonstrated that this motif is not restricted to alpha-amylases, but is also found in 80 structures from 33 different proteins, amongst which SH2 domain-containing proteins are the best representatives. [less ▲]Detailed reference viewed: 17 (2 ULg) Le nonce et le confesseur princier: jeux d'influence au sein des Pays-Bas espagnols durant la première moitié du xviie sièclePirlet, Pierre-François in Revista de la Inquisicion (2012), 16À Bruxelles, à la cour des archiducs puis des Gouverneurs-généraux, le confesseur princier est vu comme un personnage influent. Les nonces, soutenus par la secrétairerie d'État romaine, vont développer ... [more ▼]À Bruxelles, à la cour des archiducs puis des Gouverneurs-généraux, le confesseur princier est vu comme un personnage influent. Les nonces, soutenus par la secrétairerie d'État romaine, vont développer, au cours du xviie siècle, un ensemble de stratégies pour faire de ce personnage la pièce maîtresse de leur action. Ces religieux, quant à eux, se considèrent plutôt comme les serviteurs de la Couronne espagnole, dont les intérêts ne sont pas toujours en phase avec ceux de la papauté. Cette étude vise à démontrer l'asymétrie de la relation entre confesseurs et diplomates romains. [less ▲]Detailed reference viewed: 53 (13 ULg) Nonclinical Participants' Reports of Hallucinatory ExperiencesLaroi, Frank ; Van der Linden, Martial in Canadian Journal of Behavioural Science = Revue Canadienne des Sciences du Comportement (2005), 37Hallucinatory experiences in nonclinical subjects were examined using a French adaptation of a self-report questionnaire (Launay-Slade Hallucinations Scale; LSHS). The factor structure of this ... [more ▼]Hallucinatory experiences in nonclinical subjects were examined using a French adaptation of a self-report questionnaire (Launay-Slade Hallucinations Scale; LSHS). The factor structure of this questionnaire was examined. In addition to prevalence, we explored various characteristics of the reported hallucinatory experiences, including frequency, degree of control, emotional reaction, relationship to stressful events, and personal saliency. We also examined the relationship between the presence of hallucinatory experiences and other factors, such as substance use and social desirability. Two hundred and thirty-six nonclinical participants completed a modified version of the LSHS, a social desirability scale, and answered follow up questions. Factor analysis of the present version of the LSHS revealed a five-factor structure. Results regarding participants' hallucination frequency, perceived levels of control, and affective responses are reported. Additional results and implications are discussed. [less ▲]Detailed reference viewed: 95 (8 ULg) Noncollinear magnetism and single-ion anisotropy in multiferroic perovskitesWeingart, C.; Spaldin, N.; Bousquet, Eric in Physical Review. B, Condensed Matter and Materials Physics (2012), 86(9), The link between the crystal distortions of the perovskite structure and the magnetic exchange interaction, the single-ion anisotropy (SIA), and the Dzyaloshinsky-Moriya (DM) interaction are investigated ... [more ▼]The link between the crystal distortions of the perovskite structure and the magnetic exchange interaction, the single-ion anisotropy (SIA), and the Dzyaloshinsky-Moriya (DM) interaction are investigated by means of density functional calculations. Using BiFeO 3 and LaFeO 3 as model systems, we quantify the relationship between the oxygen octahedra rotations, the ferroelectricity, and the weak ferromagnetism (wFM). We recover the fact that the wFM is due to the DM interaction induced by the oxygen octahedra rotations. We find a simple relationship between the wFM, the oxygen rotation amplitude, and the ratio between the DM vector and the exchange parameter such that the wFM increases with the oxygen octahedra rotation when the SIA does not compete with the DM forces induced on the spins. Unexpectedly, we also find that in spite of the d5 electronic configuration of Fe3 +, the SIA is very large in some structures and is surprisingly strongly sensitive to the chemistry of the A-site cation of the ABO 3 perovskite. In the ground R3c state phase we show that the SIA shape induced by the ferroelectricity and the oxygen octahedra rotations are in competition such that it is possible to turn the wFM "on" and "off" through the relative size of the two types of distortion. © 2012 American Physical Society. [less ▲]Detailed reference viewed: 31 (3 ULg) Noncollinear magnetism in post-perovskites from first-principles: Comparison between CaRhO3 and NaNiF3Garcia Castro, Andrés Camilo ; Romero, Aldo; Bousquet, Eric in Physica Status Solidi B. Basic Research (2015), 252(4), 689Based on first-principles calculations, we study the noncollinear magnetism in the post-perovskites (pPv) phase of NaNiFinline image and CaRhOinline image crystals. We find that the magnetic canting is ... [more ▼]Based on first-principles calculations, we study the noncollinear magnetism in the post-perovskites (pPv) phase of NaNiFinline image and CaRhOinline image crystals. We find that the magnetic canting is one of the most promising properties of pPv systems, which is allowed by symmetry in all the pPv crystals inline image with a magnetically active B-site. In the pPv phase of NaNiFinline image, which has a inline image antiferromagnetic ground state with a inline image ferromagnetic canting, we obtain a magnetic canting amplitude of about 0.1 inline imageatominline image, which is much larger than in the one obtained in CaRhOinline image (canting amplitude of 0.04 inline image). We also computed the exchange constants (inline image), the single-ion anisotropy (SIA) parameters and the anti-symmetric magnetic coupling described by the Dzyaloshinsky–Moriya (DM) interaction in order to scrutinize the origin of the magnetic canting. We find that the canting in NaNiFinline image is mainly due to the DM interaction, while in CaRhOinline image, both DM and SIA contribute to the magnetic canting. Our calculations thus confirm the noncollinear magnetic ground-state solution experimentally observed in both compounds and the calculated magnetic exchange interactions also confirm the quasi-2D magnetic behavior reported in pPv. [less ▲]Detailed reference viewed: 25 (3 ULg) Noncommutative and nonassociative algebrasKreusch, Marie Conference (2015, March 31)We choose the abelian group ($\bbZ_2^n, +$) where $\bbZ_2 = \bbZ / 2 \bbZ$ and define a $\bbZ_2^n$-graded vector space $E = \bigoplus_{x \in \bbZ_2^n} E_x$ together with a multiplication $\cdot :E ... [more ▼]We choose the abelian group ($\bbZ_2^n, +$) where$\bbZ_2 = \bbZ / 2 \bbZ$and define a$\bbZ_2^n$-graded vector space $E = \bigoplus_{x \in \bbZ_2^n} E_x$ together with a multiplication$ \cdot :E \times E \longrightarrow E$respecting the grading $E_x \cdot E_y \subset E_{x+y} \quad \forall x,y \in \bbZ_2^n.$ This is called a$\bbZ_2^n$-graded algebra. We are interested in particular$\bbZ_2^n$-graded algebras where the product in noncommutative and nonassociative. This talk consists of two parts. The first one is the study of a series of$\bbZ_2^n$-graded algebras of finite dimension ($2^n$) where$n \geq 3$. This series of real noncommutative and nonassociative algebras, denoted$\bbO_{p,q}$($p+q=n$), generalizes the algebra of octonion numbers$\bbO$. This generalization is similar to the one of the algebra of quaternion numbers in Clifford algebras. The first \emph{question} is to classify these algebras up to isomorphisms. The classification table of$\bbO_{p,q}$is quite similar to that of the real Clifford algebras$\cC l_{p,q}$. The second \emph{question} is to find a periodicity between these algebras. The periodicity for the algebras$\bbO_{p,q}$is analogous to the periodicity for the Clifford algebras$\cC l_{p,q}$. In the second part we study$\bbZ_2$-graded algebras ($n=0$, superalgebras'') that can be of infinite dimension. We consider two kind of superalgebras$\cL_{g,N}$and$\cJ_{g,N}$that are noncommutative and nonassociative\footnote{The construction coming from spaces on a compact Riemann surface of genus$g$with$N$punctures}. Nevertheless, these superalgebras link together the classical Lie algebras and the classical commutative and associative algebras. The two last \emph{questions} are can we extend'' the algebras$\cL_{g,N}$and$\cJ_{g,N}$? The first answer is yes (for$\cL_{g,N}$), while the second one is no (for$\cJ_{g,N}$). However, we can extend'' module$\cJ_{g,N}^*\$. [less ▲]Detailed reference viewed: 11 (1 ULg) Nonconsumption of the reinforcer under drug actionFaidherbe, J.; Richelle, Marc ; Schlag, J.in Journal of the Experimental Analysis of Behavior (1962), 5(4), 521-524Detailed reference viewed: 8 (3 ULg) Nonconventional radiographic projections in the equine orthopaedic examinationRichard, Eric ; Alexander, Katein Equine Veterinary Education (2007), 19(10), 551-559Detailed reference viewed: 24 (5 ULg)