Second-Order Noncausality in Multivariate GARCH Processes

Typical multivariate economic time series may exhibit co-behavior patterns not only in the conditional means, but also in the conditional variances. In this paper we give two new definitions of variance noncausality in a multivariate setting a Granger-type noncausality and a linear Granger noncausality through projections on Hilbert spaces. Both definitions are related to a previous second-order noncausality concept defined by Granger et al . in a bivariate setting. The implications of second-order noncausality on multivariate ARMA processes with GARCH-type errors are investigated. We derive exact testable restrictions on the parameters of the processes considered, implied by this type of noncausality. Conditions for the finiteness of the fourth-order moment of the multivariate GARCH process are derived and related to earlier results in the univariate framework. We include an illustration of second-order noncausality in a trivariate model of daily financial returns.     

Atmospheric deposition and migration of artificial radionuclides in Alpine soils (Val Piora, Switzerland) compared to the distribution of selected major and trace elements

Artificial radionuclides (¹³⁷Cs, ⁹⁰Sr, Pu, and ²⁴¹Am) are present in soils because of Nuclear Weapon Tests and accidents in nuclear facilities. Their distribution in soil depth varies according to soil characteristics, their own chemical properties, and their deposition history. For this project, we studied the atmospheric deposition of ¹³⁷Cs, ⁹⁰Sr, Pu, ²⁴¹Am, ²¹⁰Pb, and stable Pb. We compared the distribution of these elements in soil profiles from different soil types from an alpine Valley (Val Piora, Switzerland) with the distribution of selected major and trace elements in the same soils. Our goals were to explain the distribution of the radioisotopes as a function of soil parameters and to identify stable elements with analogous behaviors. We found that Pu and ²⁴¹Am are relatively immobile and accumulate in the topsoil. In all soils, ⁹⁰Sr is more mobile and shows some accumulations at depth into Fe-Al rich horizons. This behavior is also observed for Cu and Zn, indicating that these elements may be used as chemical analogues for the migration of ⁹⁰Sr into the soil.     

The Impact of Cyclopropane Configuration on the Biological Activity of Cyclopropyl‐Epothilones

Two cis‐12,13‐cyclopropyl‐epothilone B variants have been synthesized, differing only in the configuration of the stereocenters at C12 and C13. The syntheses were based on a common allylic alcohol intermediate that was converted into the corresponding diastereomeric hydroxymethyl‐cyclopropanes by means of stereoselective Charette cyclopropanations. Macrocyclizations were accomplished through ring‐closing metathesis (RCM). Substantial differences between the two compounds were found with regard to microtubule binding affinity, antiproliferative activity and their effects on the cellular microtubule network. While the analogue with the cyclopropane moiety oriented in a corresponding way to the epoxide configuration in natural epothilones was almost equipotent with epothilone A, the other was significantly less active. Based on these findings, natural epothilone‐like activity of cis‐fused 12,13‐cyclopropyl‐epothilone analogues is tightly linked to the natural orientation of the cyclopropane moiety.     

Naloxone, but not flupenthixol, disrupts the development of conditioned ejaculatory preference in the male rat.

Male rats display a conditioned preference to ejaculate with a female bearing an odor paired previously with copulation to ejaculation. The present study examined the role of endogenous opioid and dopamine systems in this preference. Male rats received saline, the opioid receptor antagonist naloxone, or the dopamine receptor antagonist flupenthixol prior to 10 conditioning trials in a pacing chamber with an almond-scented female. On the final test, all males were injected with saline and given access to 2 females, 1 scented and the other unscented, in an open field. Only males injected with naloxone during training failed to manifest a conditioned ejaculatory preference. These findings suggest that activation of opioid, but not dopamine, systems during sexual interaction are necessary for conditioned ejaculatory preference in male rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does Biotech Reflect a New Science-based Innovation Regime?

The purpose of this paper is to enter into the ""black box' of science-based sectors, to seek a better understanding of the nature of the dynamics of such technological regimes in their different forms. Special attention is given to the institutional dimensions, which, in the authors' view, play a major role in structuring technological regimes and organizational trajectories. After a short review of the literature on science-based sectors and technological regimes, some specificities of the new emerging biotech sector are focused on, aiming to show how and why it can be regarded as a new type of science-based technological regime, referred to in this paper as the science-based ""type 2' model. In a short final conclusion, some of the consequences of the existence of this basic distinction between two types of ""science-based' regime are explored.     

Controlled modification of octadecyltrichlorosilane self-assembled monolayer by CO2 plasma

CO₂-plasma is used to introduce functional groups on the uppermost surface of an alkoxysilane self-assembled monolayer (SAM). The structural and chemical modifications of the material surface were monitored by X-ray reflectometry, atomic force microscopy, X-ray photoelectrons spectroscopy and water contact angle measurements. Optimization of the plasma parameters is performed in order to achieve a maximum functionalization and to prevent degradation of the SAM. Finally, the ability of grafting organic compounds onto the plasma modified SAMS was demonstrated by the formation of an alkoxysilane bilayer.     

Tight Junctions as a Key for Pathogens Invasion in Intestinal Epithelial Cells

Tight junctions play a major role in maintaining the integrity and impermeability of the intestinal barrier. As such, they act as an ideal target for pathogens to promote their translocation through the intestinal mucosa and invade their host. Different strategies are used by pathogens, aimed at directly destabilizing the junctional network or modulating the different signaling pathways involved in the modulation of these junctions. After a brief presentation of the organization and modulation of tight junctions, we provide the state of the art of the molecular mechanisms leading to permeability breakdown of the gut barrier as a consequence of tight junctions’ attack by pathogens, including bacteria, viruses, fungi, and parasites.     

Accelerated ageing of polypropylene stabilized by phenolic antioxidants under high oxygen pressure

Polypropylene (PP) samples stabilized by a hindered phenol (Irganox 1010) were submitted to thermal ageing at 80°C in air at atmospheric pressure or in pure oxygen at 5.0 MPa pressure. Both the polymer oxidation and the stabilizer consumption were monitored by Infrared spectrometry and thermal analysis. The stabilizer efficiency, as assessed by the ratio induction time/stabilizer concentration is almost constant at atmospheric pressure even when the stabilizer concentration is higher than its solubility limit in PP (0.4% or 24 × 10^?3 mol L^?1). In contrast, at high pressure, the efficiency decreases almost hyperbolically with the stabilizer concentration when this latter is higher than 6.0 × 10^?3 mol L^?1. The results indicate the existence of a direct phenol‐oxygen reaction negligible at low oxygen pressure but significant at 5.0 MPa pressure. The reality of this reaction has been proved on the basis of a study of the thermal oxidation of a phenol solution in a nonoxidizable solvent. A kinetic model of PP oxidation in which stabilization involves three reactions has been proposed. It simulates correctly the effect of oxygen pressure and stabilizer concentration on carbonyl build‐up and stabilizer consumption. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Physico‐chemical,thermal, and mechanical approaches for the characterization of solubilized and solid state chitosans

This study was conducted on the both solid and solubilized chitosans to propose an approach for the physico‐chemical, thermal and mechanical characterizations of this polysaccharide. The polysaccharide used was a 90% deacetylated chitosan having a molecular weight of 98.4 kDa. The flow property of chitosan solutions was evaluated revealing a shear‐thinning behavior. The thermal characterization was carried out by studying heat specific capacity, glass transition temperature, and thermal conductivity on chitosan dried specimens (solid state). Their T_g were measured by DSC and confirmed by DMA at 102 and 122°C depending on concentrations of initial chitosan solutions. The mechanical characterization was conducted by analyzing Young modulus, tensile strength, and elongation at break of chitosan specimens. They exhibited a higher elongation at break and a lower tensile strength when made from high concentrated chitosan solution (9% w/v). Differences in mechanical behavior of specimens were explained by differences of crystallinity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41257.     

The Metalloporphyrin Antioxidant, MnTE-2-PyP, Inhibits Th2 Cell Immune Responses in an Asthma Model

MnTE-2-PyP, a superoxide dismutase mimetic, inhibited OVA-induced airway inflammation in mice suggesting an effect on Th2 responsiveness. Thus, we hypothesized that MnTE-2-PyP may alter dendritic cell-Th2 interactions. Bone marrow derived dendritic cells (DC) and OVA(323-339)-specific Th2 cells were cultured separately in the presence or absence of MnTE-2-PyP for 3 days prior to the co-culturing of the two cell types in the presence of an OVA(323-339) peptide and in some cases stimulated with CD3/CD28. MnTE-2-PyP-pretreated DC inhibited IL-4, IL-5 and IFNγ production and inhibited Th2 cell proliferation in the DC-Th2 co-culturing system in the presence of the OVA(323-339) peptide. Similar results were obtained using the CD3/CD28 cell-activation system; the addition of MnTE-2-PyP inhibited Th2 cell proliferation. MnTE-2-PyP suppressed CD25 expression on OVA-specific Th2 cells, which implied that MnTE-2-PyP can inhibit the activation of Th2 cells. MnTE-2-PyP also down-regulated co-stimulatory molecules: CD40, CD80 and CD86 on immature DC. Our studies suggest that the major mechanism by which MnTE-2-PyP inhibits airway inflammation is by acting on the DC and suppressing Th2 cell proliferation and activation.