Nonlinear filtering with a symmetric space valued discontinuous observation

The aim of this paper is to derive the Zakai equation associated with nonlinear filtering problems when the observation process is discontinuous and takes its values in a Riemannian symmetric space. The main tools are the stochastic development and the horizontal lift of manifold–valued càdlàg semimartingales     

EFFECTS OF in vitro EXPOSURE TO ULTRAVIOLET RADIATION ON THE FUNCTIONAL ACTIVITY OF LYMPHOCYTES, WITH EMPHASIS ON SUSCEPTIBILITY OF DIFFERENT SPECIES

Abstract In this study lymphocytes from blood and/or spleen of different species (rat, mouse, human) were exposed to different doses of ultraviolet radiation (UVR). The functional activity of these lymphocytes was determined using assays for mitogen proliferation and the mixed lymphocyte response (MLR). These experiments demonstrated that in vitro exposure to UVR causes a dose-dependent decrease of the MLR activity of the irradiated lymphocytes. Viability of lymphocytes and mitogen proliferation responses were also decreased by UVR exposure but less severe in comparison to the MLR. Lymphocytes of rats seem to be more sensitive to UVR as compared to lymphocytes of mice and humans.     

Étude par chromatographie gaz-solide du polyoxyéthylène a l'état semi-cristallin

Study of the system poly(ethylene oxide) $\text{(}\text{M}{}_{\mathrm{w}}\text{= 11,500}\text{)-n-}\text{decane}$ by gas-solid chromatography leads to two main conclusions: adsorption of the probe at the various interfaces is never negligible, in spite of the lack of any strong specific interaction between the alkane and the polyether. Reliable values of the degree of crystallinity may be however derived from measurements, taking into account these adsorption phenomena. The sharp increases of the specific retention volumes (V_g⁰) observed at well defined temperatures (about 42.3 and 51.4°C) are directly related to the well known chain unfolding ν4 → 3 and ν3 → 2 in the crystalline lamellae.     

A two-dimensional model for collisional energy transfer in bimolecular ion-molecule dynamics: M++(H2; D2; or HD)→(MH++H; MD++D; MH++D; or MD++H)

Summary Guided ion beam kinetic energy thresholds in the ion-molecule reactions M⁺+H₂MH⁺+H, where M⁺ is a closed-shell atomic ion B⁺, Al⁺, or Ga⁺, were found to exceed by 0.4 to ca. 5 eV the thermodynamic energy requirements (or the theoretically computed barrier heights) for these reactions. In addition, the formation of MD⁺ occurs at a significantly lower threshold than MH⁺ when M⁺ reacts with HD. Moreover, the measured reaction cross-sections for the production of MH⁺ or MD⁺ product ions are very small (10^–17 to 10^–20 cm²), being largest for B⁺ and smallest for Ga⁺. A previous paper from this group proposed that collisional-to-internal energy transfer is the rate-limiting step for this class of reactions. It also suggested, based on a dynamical resonance picture, that collisions occurring at or near C_2v symmetry are more effective than other collisions even though C_2v geometries provide no lower potential energy barriers than others. By examining the collision paths characteristic of flux early in the bimolecular collision and searching for geometries along such paths where collisional-to-internal energy transfer is optimal, our earlier efforts predicted reaction thresholds in reasonable agreement with the (previously perplexing) experimental data. In the present work, we introduce a model Hamiltonian whose classical and quantum dynamics we apply to the M⁺+H₂, D₂, HD reactive collisions. We calculate the classical collisional-to-internal energy transfer cross-sections and find energy transfer thresholds that resemble the experimental reaction thresholds but whose isotopic mass trends are not entirely consistent with experiment. We then use a Green function method and a local quadratic approximation to the potential surface to obtain analytical expressions for the isotopic mass dependences of the collisional-to-vibrational energy transfer and for the subsequent fragmentation of the three-atom system. Finally, we analyze the origin of the threshold energy asymmetry in the M⁺+HD reactions.     

Silicon and phosphorus alkoxide mixture: Sol-gel study by spectroscopic technics

Sol-gel synthesis of mixtures of tetraethoxysilane and a phosphorus alkoxide [P(OEt)₃ or (OEt)₂P-O-P(OEt)₂ or PO(OEt)₃] have been studied by ¹H, ¹³C²⁹Si and ³¹P liquid and solid state NMR, infrared and raman spectroscopies. This study shows different behaviors towards hydrolysis for these three different phosphates and phosphites. P(OEt)₃ almost instantly reacts with water to form an intermediate species HPO(OEt)₂, which slowly evolves first to HPO(OH)(OEt), then to HPO(OH)₂ a few days later. For (OEt)₂P-O-P(OEt)₂, the P-O-P bond is broken when water is added, then the same intermediates are formed faster. PO(OEt)₃ is hydrolyzed much slower than the other alkyl phosphates. After ten months, triethoxyphosphate is quantitatively present in the sol with little PO(OH)(OEt)₂ species. All these hydrolyzed species are well characterized. Only the system which contains the tetraethoxysilane and the triethoxyphosphite P(OEt)₃ forms a few P-O-P and P-O-Si bonds in the gel. Hydrolysis of tetraethoxysilane is much faster than that of phosphorus alkoxides and the conventional Q₂, Q₃ and Q₄ condensed silicon species form the gel three dimensional network.     

Theoretical study of water-pyridine complexes using intermolecular potentials

Intermolecular potential functions have been used to determine the equilibrium structures of the water-pyridine complexes. The dimer and symmetrical 2:1 water pyridine systems have been studied. Three water models, ST2, TIPS2, and EMPWI have been combined with two different Lennard Jones nonbonded parameters and various charge distributions for the pyridine molecule to describe the systems. For the dimer, results show two distinguishable classes of preferential hydration sites, which are specific sites corresponding to hydrogen-bonded dimer and nonspecific sites located near the hydrophobic regions. Calculations performed on hydrogen-bonded symmetrical complexes show that the planar complex is generally less stable than the complex with water molecules perpendicular to the pyridine plane. For these complexes, the major factor that influences the hydrogen-bonded configurations is the choice of the water model. The importance of atomic charge distributions for the solute over the choice of potential parameters is pointed out. Finally, the effective lone pair representation on the aromatic nitrogen atom is shown to improve the hydrogen bond geometry and the stability of the complexes.     

La reaction de wittig-horner en milieu heterogene VI1. Selectivite de la reaction sur des composes bifonctionnels

Heterogenous media of low basicity (K₂CO₃ or KHCO ₃), liquid-liquid or solid-liquid allow the Wittig-Horner reaction of fragile and unprotected aldehydes (hydroxyaldehydes, nitroaldehyde and ketoaldehydes) with excellent yields. The reaction is applied to the synthesis of Royal Jelly acid and Queen Substance of Honey bee.     

Thermodynamique des complexes metalliques ternaires des amino acides: Etude du systeme Ni(II)—Glycine—DL-α-alanine

Standard enthalpies and entropies of formation for binary and ternary Ni(II) complexes with glycine and DL-α-alanine were calorimetrically determined at 25°C in aqueous solution (I = 1 M NaClO₄). The evolution of these values from binary to ternary complexes is discussed on the basis of the stabilization characterizing the stability constants of the ternary species which have been previously calculated under the same experimental conditions.     

Investigation of orientational behaviour of nematic and smectic a compounds using the Raman microprobe

The Raman microprobe technique, has been used to probe orientational order in oriented samples of nematic CB₅ and nematic and smectic CB₈ versus spatial localization of the analysed microvolume. In the nematic state, the influence of long-wavelength director fluctuations is pointed out and an elastic constant derived.     

Chemical and photochemical reactivity in micellar media and microemulsions VII- Effect of the interface on the reactivity of excited states

Study of the photodimerization of coumarin in micellar media and microemulsions shows that the orientation and the concentration of molecu- les in the interfacial film can favor reactions involving just one of the excited states (the singlet state in this case).