2,237 research outputs found

    An obstruction for q-deformation of the convolution product

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    We consider two independent q-Gaussian random variables X and Y and a function f chosen in such a way that f(X) and X have the same distribution. For 0 < q < 1 we find that at least the fourth moments of X + Y and f(X) + Y are different. We conclude that no q-deformed convolution product can exist for functions of independent q-Gaussian random variables.Comment: The proof of proposition 2 is corrected on 11 january 199

    Accurate Fundamental Stellar Parameters

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    We combine results from interferometry, asteroseismology and spectroscopic analyses to determine accurate fundamental parameters (mass, radius and effective temperature) of 10 bright solar-type stars covering the H-R diagram from spectral type F5 to K1. Using ``direct'' techniques that are only weakly model-dependent we determine the mass, radius and effective temperature. We demonstrate that model-dependent or ``indirect'' methods can be reliably used even for relatively faint single stars for which direct methods are not applicable. This is important for the characterization of the targets of the CoRoT and Kepler space missions.Comment: 2 pages. To appear in the proceedings of IAU Symp. 265: Chemical Abundances in the Universe: Connecting First Stars to Planet

    The distinction of 'Psychosomatogenic family types' Based on parents' self reported questionnaire information: a cluster analysis

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    The theory of 'psychosomatogenic family types' is often used in treatment of somatizing adolescents. This study investigated the validity of distinguishing 'psychosomatogenic family types' based on parents' self-reported family features. The study included a Flemish general population sample of 12-year olds (n = 1428). We performed cluster analysis on 3 variables concerning parents' self-reported problems in family functioning. The distinguished clusters were examined for differences in marital problems, parental emotional problems, professional help for family members, demographics, and adolescents' somatization. Results showed the existence of 5 family types: 'chaotic family functioning,' 'average amount of family functioning problems,' 'few family functioning problems,' 'high amount of support and communication problems,' and ' high amount of sense of security problems' clusters. Membership of the 'chaotic family functioning' and 'average amount of family functioning problems' cluster was significantly associated with higher levels of somatization, compared with 'few family functioning problems' cluster membership. Among additional variables, only marital and parental emotional problems distinguished somatization relevant from non relevant clusters: parents in 'average amount of family functioning problems' and 'chaotic family functioning' clusters reported higher problems. The data showed that 'apparently perfect' or 'enmeshed' patterns of family functioning may not be assessed by means of parent report as adopted in this study. In addition, not only adolescents from 'extreme' types of family functioning may suffer from somatization. Further, professionals should be careful assuming that families in which parents report average to high amounts of family functioning problems also show different demographic characteristics

    Calcifying vascular smooth muscle cells and osteoblasts: Independent cell types exhibiting extracellular matrix and biomineralization-related mimicries

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    Background: Ectopic vascular calcifications represent a major clinical problem associated with cardiovascular disease and mortality. However, the mechanisms underlying pathological vascular calcifications are largely unknown hampering the development of therapies to tackle this life threatening medical condition. Results: In order to gain insight into the genes and mechanisms driving this pathological calcification process we analyzed the transcriptional profile of calcifying vascular smooth muscle cells (C-VSMCs). These profiles were compared to differentiating osteoblasts, cells that constitute their physiological calcification counterparts in the body. Overall the transcriptional program of C-VSMC and osteoblasts did not overlap. Several genes, some of them relevant for bone formation, were distinctly modulated by C-VSMCs which did not necessarily lose their smooth muscle cell markers while calcifying. Bioinformatics gene clustering and correlation analysis disclosed limited bone-related mechanisms being shared by two cell types. Extracellular matrix (ECM) and biomineralization genes represented common denominators between pathological vascular and physiological bone calcifications. These genes constitute the strongest link between these cells and represent potential drivers for their shared end-point phenotype. Conclusions: The analyses support the hypothesis that VSMC trans-differentiate into C-VSMCs keeping their own identity while using mechanisms that osteoblasts use to mineralize. The data provide novel insights into groups of genes and biological processes shared in MSC and VSMC osteogenic differentiation. The distinct gene regulation between C-VSMC and osteoblasts might hold clues to find cell-specific pathway modulations, opening the possibility to tackle undesired vascular calcifications without disturbing physiologic bone formation and vice versa

    CRIQ: An innovative measure using comparison awareness to avoid self-presentation tactics

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    The article presents a new measure for career role identification, the Career Role Identification Questionnaire (CRIQ). In constructing the CRIQ, we used the Comparison Awareness Inducing Technique (CAIT), a new and innovative method to reduce the effects of self-presentation tactics. The results show that the CRIQ measures identification with the six career roles conceptualized by Hoekstra (2011). The inventory has reliable scales and a clear factorial structure. Furthermore, the CAIT receives some support as a new way to deal with the problem of social desirability in self-report measures. The CAIT technique is thought to induce comparison awareness and thus suppress various response tendencie

    Agenda praktijkgericht onderzoek health:Topsector Life Sciences &amp; Health

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    De Regiegroep van de topsector Life Sciences & Health wil een impuls geven aan initiatieven die praktijkgericht onderzoek op het gebied van Health betreffen. De redenen hiervoor zijn de relatief bescheiden positie van Health vergeleken bij de Life Sciences in de eerdere agendering onder de topsector en de verwachting dat praktijkgericht onderzoek door hogescholen een substantiële bijdrage kan leveren aan de doelstellingen onder het topsectorenbeleid. Daarom is opdracht gegeven tot het opstellen van een agenda voor praktijkgericht onderzoek “Health”. Deze agenda moet leiden tot samenwerking met een solide economische component tussen hogescholen, eventuele andere kennisinstellingen en publieke en private partijen uit de beroepspraktijk. De Agenda Praktijkgericht Onderzoek Health is ingedeeld in vier overkoepelende thema’s (A - D) waarop het onderzoek van hogescholen zich zou moeten richten. Binnen elk thema zijn onderwerpen benoemd die op basis van deze verkenning prioriteit verdienen

    Genetics and biology of vitamin D receptor polymorphisms

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    The vitamin D endocrine system is involved in a wide variety of biological processes including bone metabolism, modulation of the immune response, and regulation of cell proliferation and differentiation. Variations in this endocrine system have, thus, been linked to several common diseases, including osteoarthritis (OA), diabetes, cancer, cardiovascular disease, and tuberculosis. Evidence to support this pleiotropic character of vitamin D has included epidemiological studies on circulating vitamin D hormone levels, but also genetic epidemiological studies. Genetic studies provide excellent opportunities to link molecular insights with epidemiological data and have therefore gained much interest. DNA sequence variations, which occur frequently i

    Inhibition of insulin- and insulin-like growth factor-I-stimulated growth of human breast cancer cells by 1,25-dihydroxyvitamin D3 and the vitamin D3 analogue EB1089

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    1, 25 Dihydroxyvitamin D3 (1,25-(OH)2D3) and a number of synthetic vitamin D3 analogues with low calcaemic activity, have been shown to inhibit breast cancer cell growth in vitro as well as in vivo. The purpose of the present study was to investigate a possible interaction of 1, 25-(OH)2D3 and the vitamin D3 analogue EB1089 with the insulin-IGF-I regulatory system. The oestrogen receptor-positive MCF-7 human breast cancer cells used in this study are able to grow autonomously and their growth is stimulated by insulin. In order to avoid interference of IGF-binding proteins (IGF-BPs), we used an analogue of IGF-I, long R3 IGF-I, which stimulated MCF-7 cell growth similar to insulin. The growth stimulation by insulin and by long R3 IGF-I was completely inhibited by 1,25-(OH)2D3 and EB1089. Autonomous growth was also inhibited by 1,25-(OH)2D3 and EB1089. The analogue EB1089 was active at 50 times lower concentrations than 1,25-(OH)2D3. It was shown that growth inhibition was not achieved through downregulation of insulin and IGF-I binding after 48 h. Paradoxically, after prolonged treatment (8 days), an upregulation of insulin and IGF-I binding was observed. Two possible intracellular mediators of the insulin-IGF mitogenic signal are C-FOS and mitogen-activated protein (MAP) kinase. Insulin-induced C-FOS mRNA was inhibited by 1,25-(OH)2D3, suggesting that it could be involved in the growth inhibition by 1,25-(OH)2D3. MAP kinase activation appeared not to be involved in growth stimulation by both insulin and IGF-I. Together, the present study demonstrates that vitamin D3 compounds can block the mitogenic activity of insulin and IGF-I, which may contribute to their tumour suppressive activity observed in vivo. Copyrigh
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