Numerical modeling of wave propagation in anisotropic viscoelastic laminated materials in transient regime: Application to modeling ultrasonic testing of composite structures

Composite laminate structures remain an important family of materials used in cutting-edge industrial areas. Building efficient numerical modeling tools for high-frequency wave propagation in order to represent ultrasonic testing experiments of these materials remains a major challenge. In particular, incorporating attenuation phenomena within anisotropic plies, and thin intermediate isotropic layers between the plies often represent significant obstacles for standard numerical approaches. In our work, we address both issues by proposing a systematic study of the fully discrete propagators associated to the Kelvin-Voigt, Maxwell, and Zener models, and by incorporating effective transmission conditions between plies using the mortar element method. We illustrate the soundness of our approach by proposing intermediate one-dimensional and two-dimensional numerical evidence, and we apply it to a more realistic configuration of a curved laminate composite structure in a three-dimensional setting.     

The possible involvement of LH/hCG induced mitochondrial proteins in the regulation of steroidogenesis in bovine luteal cells

Beta-2-microglobulin (B2M) forms the small invariable light chain subunit of class I HLA antigens on the cell membrane of all nucleated cells. During the continuous turnover of the HLA molecules, B2M is shed from the cell membrane into blood. Lymphocytes are the main source of serum free B2M. Serum B2M concentration is increased in renal diseases, various malignant diseases and some inflammatory and autoimmune disorders. In lymphatic malignancies serum B2M has significant prognostic value. Interferons (IFNs) have the ability to enhance the expression of class I and II histocompatibility antigens. Accordingly, IFNs cause a rise in formation and release of B2M. Currently, treatment with IFN alpha is used in diseases, like multiple myeloma, where serum B2M measurements are used to assess tumor burden. We have measured serum B2M levels during IFN alpha treatment in patients with both multiple myeloma and chronic myeloproliferative diseases, and IFN alpha caused a significant increase in serum B2M. It can be concluded that use of IFN alpha abolishes the value of serum B2M as an indicator of disease activity.     

A method for the transformation of factors in factor analysis

A method is proposed for obtaining combinations of factors derived from a factor analysis characterized by a large number of near-zero loadings relative to the original variables. It differs from rotation of factors, which replaces r factors by an equal number, r, of differently oriented factors, in that each solution consists of a single direction in F variable space.     

The medial scaffold of 3D unorganized point clouds

We introduce the notion of the medial scaffold, a hierarchical organization of the medial axis of a 3D shape in the form of a graph constructed from special medial curves connecting special medial points. A key advantage of the scaffold is that it captures the qualitative aspects of shape in a hierarchical and tightly condensed representation. We propose an efficient and exact method for computing the medial scaffold based on a notion of propagation along the scaffold itself, starting from initial sources of the flow and constructing the scaffold during the propagation. We examine this method specifically in the context of an unorganized cloud of points in 3D, e.g., as obtained from laser range finders, which typically involve hundreds of thousands of points, but the ideas are generalizable to data arising from geometrically described surface patches. The computational bottleneck in the propagation-based scheme is in finding the initial sources of the flow. We thus present several ideas to avoid the unnecessary consideration of pairs of points which cannot possibly form a medial point source, such as the "visibility of a point from another given a third point and the interaction of clusters of points. An application of using the medial scaffold for the representation of point samplings of real-life objects is also illustrated     

Hormonal regulation of apoptosis in rabbit granulosa cells in vitro: evaluation by flow cytometric detection of plasma membrane phosphatidylserine externalization

Annexin V and propidium iodide bivariate analysis and the TUNEL method were used to quantify hormonal regulation of apoptosis in rabbit granulosa cells from preovulatory follicles in vitro. The aim of this study was to analyse comparatively the effects of gonadotrophins and their second messenger in the regulation of granulosa cell apoptosis in (i) cultured isolated granulosa cells and (ii) granulosa cells scraped from cultured follicles. The results showed that increasing doses of FSH had no effect on apoptosis of cultured isolated cells but caused a decrease in the number of apoptotic granulosa cells from preovulatory follicles cultured in serum-free conditions. Unlike FSH, addition of hCG did not modify apoptosis of granulosa cells significantly. In contrast, dibutyryl cAMP had an apoptotic effect in the two cellular models in the presence of serum. Moreover, a biphasic effect of dibutyryl cAMP in isolated granulosa cells was observed with an increase in the incorporation of [(3)H]thymidine into DNA at the lowest dose and an increase in apoptotic cell death at the highest dose. It was concluded that, in rabbits: (i) FSH requires follicle integrity to exert its anti-apoptotic effect in granulosa cells; (ii) dibutyryl cAMP induces a dose-dependent apoptotic effect in granulosa cells cultured alone or obtained from cultured preovulatory follicles; and (iii) cAMP signals induce opposite effects on growth and apoptosis in granulosa cells.     

Life events and disability in rheumatoid arthritis: a European cohort

The objective was to study the relationship between life events (LE) and the clinical status of patients suffering from recently diagnosed rheumatoid arthritis (RA) in a 2 yr follow-up. As part of a multicentre European cohort study, 370 French and Dutch patients were questioned three times at 1 yr intervals about LE which had occurred in the previous year. Three criteria were used to quantify the degree of disease activity (Ritchie's index), the level of functional disability [Health Assessment Questionnaire (HAQ)] and perceived health [Overall Evaluation of Health (OEH)]. Total LE and desirable LE showed a weak negative correlation with the HAQ scores. On the other hand, death-related LE did not seem to modify patient status. The higher the number of health-associated LE, the greater the deterioration in HAQ and OEH scores. The results indicate that LE do not affect the course of early RA in a spectacular manner.     

Inhibition by gonadotropins of interleukin-1 production by rabbit granulosa and theca cells: effects on gonadotropin-induced progesterone production

BACKGROUND: School-based drug prevention programs have been criticized on methodologic grounds because the unit of analysis is often not the unit of randomization, thus increasing the likelihood of Type I errors. Application of multilevel analytic strategies appropriately corrects this biasing tendency. This study demonstrates the practical use of such analysis. METHODS: Data from 2,370 seventh-grade students participating in a substance use prevention trial were analyzed using a multilevel strategy. We examined the effectiveness of a social pressure resistance training and a normative education (NORM) intervention against an information-only control group. RESULTS: The NORM condition revealed 1-year program effects for cigarette and marijuana use with individuals as the unit of analysis and only marginal effects with classroom as the unit of analysis. No program effects were found using school as the analysis unit. A multilevel strategy revealed program effects for cigarettes and marijuana with both class and school as grouping levels. The effect for alcohol use was significant at the 2-year follow-up. CONCLUSIONS: Interventions establishing conservative drug use norms in classrooms may be an effective strategy in reducing substance use onset among adolescents. Utilization of appropriate analytic strategies is important in the analysis and interpretation of data containing nested structures.     

A New Role for Plastid Thioredoxins in Seed Physiology in Relation to Hormone Regulation

In Arabidopsis seeds, ROS have been shown to be enabling actors of cellular signaling pathways promoting germination, but their accumulation under stress conditions or during aging leads to a decrease in the ability to germinate. Previous biochemical work revealed that a specific class of plastid thioredoxins (Trxs), the y-type Trxs, can fulfill antioxidant functions. Among the ten plastidial Trx isoforms identified in Arabidopsis, Trx y1 mRNA is the most abundant in dry seeds. We hypothesized that Trx y1 and Trx y2 would play an important role in seed physiology as antioxidants. Using reverse genetics, we found important changes in the corresponding Arabidopsis mutant seeds. They display remarkable traits such as increased longevity and higher and faster germination in conditions of reduced water availability or oxidative stress. These phenotypes suggest that Trxs y do not play an antioxidant role in seeds, as further evidenced by no changes in global ROS contents and protein redox status found in the corresponding mutant seeds. Instead, we provide evidence that marker genes of ABA and GAs pathways are perturbed in mutant seeds, together with their sensitivity to specific hormone inhibitors. Altogether, our results suggest that Trxs y function in Arabidopsis seeds is not linked to their previously identified antioxidant roles and reveal a new role for plastid Trxs linked to hormone regulation.