Science & Mathematics

Une généralisation de la méthode de mesure de T1 (méthode d'Hervé et Pescia) et une amélioration du spectrographe utilisé pour cette méthode nous ont permis de déterminer la valeur du temps de relaxation électronique spin-réseau dans un échantillon de rubis étudié à la température ambiante.

No seminário 17 Lacan pontua que a interpretação analítica está, ela própria, na contramão do sentido comum do termo. Isso aponta para a ideia de que não é o sentido que uma interpretação visa. O que seria, então, a interpretação? Nada mais do que acontece durante uma análise. No início há a transferência do lado do analisando, no final há o passe, e no entre, há a interpretação do analista 2. Entretanto, "de um ponto de vista lógico, a interpretação antecede, causa a transferência" 3. A interpretação não intervém sem que a transferência, dispositivo imprescindível à análise, esteja estabelecida, ou seja, o analisando não valida o ato do analista sem a transferência. O ato que aponta para a não relação sexual, para o impossível, não tem possibilidade de exercer efeito algum sem transferência. Outro detalhe que merece ser destacado: só sabemos que houve interpretação a posteriori, quando um efeito acontece, pois, o inconsciente é o intérprete, é ele quem define se o ato do analista foi ou não interpretação.

L'article s'intéresse au statut ontologique des objets de l'éducation et défend à ce propos une thèse réaliste. On esquisse une typologie des compétences et des objets. Les objets de l'éducation dépendent des objets de la science (au sens large) sans leur être identiques. La notion de transposition didactique est critiquée.

Notre étude avait pour objectif de faire une étude comparative entre les enseignants novices et experts d’EPS, au collège, concernant la mise en oeuvre d’une pédagogie par les compétences, dans la compétence propre n°4. Dans cette optique, nous avons distribué, recueilli, analysé et interprété un questionnaire qui avait pour but de mettre en lumière, chez nos populations enseignantes, l’utilisation de la pédagogie par les compétences. Ainsi, de part cette étude, nous avons constaté, en nous référant aux items choisis, qu’aucune de nos trois populations ne s’inscrivait véritablement dans une mise en oeuvre quotidienne d’une « entrée par les compétences ». C’est pourquoi, nous pouvons penser que cette mise en oeuvre quotidienne n’est pas évidente et que les enseignants oscillent toujours entre une mise en oeuvre formelle et fonctionnelle.

This work reports the effect of lithium doping on the dielectric and polar properties of potassium tantalate. Experimental data were obtained in K1-xLixTaO3 ceramics with x = 0, 0.02, 0.05, and 0.10 by measuring both the dielectric permittivity from 10 2 to 10 8 Hz, and polarization under an a.c. electric field driven at 2.5 Hz, for temperatures from 10 to 300 K. The dielectric permittivity exhibits all the relaxations reported for K1-xLixTaO3 single crystals. Two dielectric relaxations observed at 40-125 K are ascribed to the individual hopping by 90 and 180° of dipoles created by the off-centre Li ions. Another relaxation observed at 100-200 K is related to 180°-flips of Li pairs for x = 0.02 and of polar clusters of interacting Li ions for x = 0.05 and 0.10. Besides that, an additional relaxation not reported before is presented at 135-235 K for x = 0.10 and attributed to 90°-reorientation of Li polar clusters. Both the change from an Arrhenius to a Vogel-Fulcher dependence with increasing lithium content, and the emergence of slim P (E) hysteresis loops around the relaxation temperatures show that the relaxation dynamics in K1-xLixTaO3 can be understood if a crossover from a dipolar glass to a relaxor-like behavior is assumed. Abstract This work reports the effect of lithium doping on the dielectric and polar properties of potassium tantalate. Experimental data were obtained in K 1-x Li x TaO 3 ceramics with x = 0, 0.02, 0.05, and 0.10 by measuring both the dielectric permittivity from 10 2 to 10 8 Hz, and polarization under an a.c. electric field driven at 2.5 Hz, for temperatures from 10 to 300 K. The dielectric permittivity exhibits all the relaxations reported for K 1-x Li x TaO 3 single crystals. Two dielectric relaxations observed at 40-125 K are ascribed to the individual hopping by 90 and 180° of dipoles created by the off-centre Li ions. Another relaxation observed at 100-200 K is related to 180°-flips of Li pairs for x = 0.02 and of polar clusters of interacting Li ions for x = 0.05 and 0.10. Besides that, an additional relaxation not reported before is presented at 135-235 K for x = 0.10 and attributed to 90°-reorientation of Li polar clusters. Both the change from an Arrhenius to a Vogel-Fulcher dependence with increasing lithium content, and the emergence of slim P (E) hysteresis loops around the relaxation temperatures show that the relaxation dynamics in K 1-x Li x TaO 3 can be understood if a crossover from a dipolar glass to a relaxorlike behavior is assumed.

Lytic polysaccharide (mono)oxygenases (LPMOs) perform oxidative cleavage of polysaccharides, and are key enzymes in biomass processing and the global carbon cycle. It has been shown that LPMO reactions may be driven by light, using photosynthetic pigments or photocatalysts, but the mechanism behind this highly attractive catalytic route remains unknown. Here, prompted by the discovery that LPMOs catalyze a peroxygenase reaction more efficiently than a monooxygenase reaction, we revisit these light-driven systems, using an LPMO from Streptomyces coelicolor (ScAA10C) as model cellulolytic enzyme. By using coupled enzymatic assays, we show that H2O2 is produced and necessary for efficient light-driven activity of ScAA10C. Importantly, this activity is achieved without addition of reducing agents and proportional to the light intensity. Overall, the results highlight the importance of controlling fluxes of reactive oxygen species in LPMO reactions and demonstrate the feasibility of light-driven, tunable enzymatic peroxygenation to degrade recalcitrant polysaccharides.

The parasitic chigger mite, Blankaartia acuscutellaris, collected from a female of Gallinago media is recorded from Poland for the first time. The locality, which constitutes the northernmost record of B. acuscutellaris in the Palaearctic, raises the question of possibility of establishing a new population on the verges of the species’ distribution range. Metric data for larvae, extending the knowledge of intra-specific variation, are provided.

This work links features of sound production in woodwinds to the action of the musician, through numerical simulation of a physical model supported by experiments. It focuses on the nonlinear dynamics of the model, as one of the missing links between the acoustical features of the instrument, and how easy it is to play. The results are intended to facilitate future instrument development endeavors that would use a physical model as a virtual prototype. Two fundamentally different simulation methods are used conjointly to provide a robust understanding of the mechanisms governing sound production in woodwind instruments. On the one hand, time-domain synthesis allows large-scale direct investigations into the transients and steady-state oscillations, with the advantage of being interpretable directly in terms of musician actions. On the other hand, the Harmonic Balance Method associated with continuation (Asymptotic Numerical Method) provides a precise, in depth investigation of stable and unstable periodic solution branches throughout the parameter space. This method highlights bifurcations which signal the apparition or disappearance of oscillation regimes: Neimark-Sacker, period doubling, Hopf and fold. These last two are followed by continuation, in codimension two. Experimental results constitute the initial foundation and final validation of numerical simulations. Input impedance measurements allow simulations to be based on the acoustical parameters of real saxophones. This justifies subsequent comparisons of simulated dynamics with phenomena observed in playing situation using an instrumented saxophone mouthpiece. Archetypes of oscillating regimes are explored and connected to musician control parameters, such as the blowing pressure and action on the reed. The so-called standard, inverted and double two-step regimes are revealed and analyzed both experimentally and numerically. The influence of geometrical and modal parameters of the resonator on the instrument’s dynamics is detailed. The dynamic system is characterized globally, by mapping out its oscillation thresholds and regime production regions. Maps representing types of oscillation regimes produced depending on the control parameters constitutes a more detailed way to compare two instruments or fingerings. They are applied to compare two alto saxophones, demonstrate the effect of the register key, and assess sound production on a virtual prototype of bicylindrical resonator. This virtual prototype's geometry is optimized based on the input impedance of a saxophone, using a differentiable cost function well-suited to gradient-based optimization procedures. A more fundamental investigation of woodwind dynamics tackles multistability (different regime being stable for the same control parameter values), which is shown to be ubiquitous on saxophones. The initial conditions leading to different regimes are grouped as attraction basins. Multistability is also characterized in a more musically interpretable way, via a variable blowing pressure transient affecting the obtained steady-state regime. These considerations are applied to improve the regime maps and avoid bias that may be due to overlooking multistable regimes. Improved regime maps are used to demonstrate that the ratio between the first two resonance frequencies leading to the most first register production is not exactly two, but a slightly higher value. The results of this dissertation and the related analysis tools further the understanding of a complex dynamic, that of the saxophone, and open the door to quantitative studies and direct application in virtual prototyping.

BACKGROUND: Iron nanoparticles (INPs) are usually prepared from inorganic sources, but we have prepared it from goat blood using incineration method. These INPs are then coated with chitosan (C) and coupled with folic acid (F) to form bionanocomposite for folate receptors. METHODS: The bionanocomposite was characterized for its physicochemical properties and cancer cell targeting studies using Fourier transform infrared spectroscopy, transmission electron microscopy, Zeta potential analysis, scanning electron microscopy-energy dispersive X-ray spectroscopy and magnetic resonance imaging analyses. RESULTS: The results have shown that the particle size of the INP-CF was found to be 80-300nm and confirmed the presence of chitosan and folic acid in the bionanocomposite. Cancer and normal mouse embryonic cell line study confirmed the internalization of INP-CF and this phenomenon was also supported by physicochemical studies. CONCLUSION: Thus, nanobiocomposite prepared using natural sources as a raw material will be beneficial compared to commercially available synthetic sources and can be used as receptor targeting agent for cancer treatment. This nanobiocomposite when coupled with substances such as monoclonal antibodies might act as a theranostic nanoagent for cancer therapy in the years to come. GENERAL SIGNIFICANCE: The prepared novel nanobiocomposite containing INPs isolated from natural source may be used as multifunctional agent due its paramagnetic property apart from its drug delivery effect.

Cet appareil est caractérisé par un dispositif original de corrélation des impulsions résultant de l'analyse d'une photographie par un balayage télévision qui permet de détecter les éléments linéaires et par une stratégie d'association de ces éléments en traces par approximations successives.

Remerciements : Les auteurs remercient la Région Auvergne Rhône Alpes pour le financement de la thèse via le CPER, le projet SCUSI AuRA ainsi que le CNRS pour le soutien apporté via le projet PEPS « RUMO ». Références : a Pambou Nziengui C.F. et al. (2019), « Notched-beam creep of douglas fir and white fir in outdoor conditions : Experimental study. » Construction Material and Building. Vol 196, 659-671. b NF EN 408+A1 (2012) Structures en bois-bois de structure et bois lamellé-collé-Détermination de certaines propriétés physiques et mécaniques.

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Dans un article paru dans La Quotidienne du 11 février 1833, le dramaturge J.-T. Merle déclare : Il y a longtemps qu'on a dit que le mélodrame n'attendait qu'un homme de génie pour tuer la tragédie. M. Hugo s'est présenté, et, en empruntant des situations à MM. Cuvelier, Caigniez ou Pixerécourt, il n'a fait, comme Molière, que prendre son bien où il le trouvait. Rédigé quelques jours après la première représentation de Lucrèce Borgia, cet article entérine une thèse largement répandue dans le milieu des théâtres du Boulevard depuis que Dumas a fait représenter Henri III et sa cour (1829) au Théâtre-Français : héritier du mélodrame, le drame romantique reprend à son compte le goût des effets et de la couleur locale, le sens du rythme et de la mise en scène, et propose une dramaturgie comparable à celle que les mélodramaturges ont édifiée et perpétuée pendant les premières décennies du siècle 2. D'abord exprimée timidement à l'égard des premiers drames hugoliens qui, parce qu'ils sont écrits en vers, supportent mal la comparaison avec le mélodrame 3 , cette thèse 1. Cet article est paru dans Méthode ! Revue de littératures, n o 14, Vallongues, 2008, p. 217-224. 2. De nombreuses parodies, jouées entre 1829 et 1843, défendent cette idée. Sur ce sujet, nous renvoyons à notre étude : « La tragédie parodiée, ou les formes en combat », Littératures classiques, Printemps 2003, n°48, p. 113-123. 3. A. Jay ose en revanche la comparaison. Dans La Conversion d'un romantique, il écrit : « Hernani, et les pièces qui lui ressemblent, ne sont que des mélodrames beaucoup moins intéressants que ceux qui se jouent sur les boulevards » (Moutardier, 1830, p. 7).