256 research outputs found
The distribution of wealth in the presence of altruism for simple economic models
We study the effect of altruism in two simple asset exchange models: the yard
sale model (winner gets a random fraction of the poorer player's wealth) and
the theft and fraud model (winner gets a random fraction of the loser's
wealth). We also introduce in these models the concept of bargaining
efficiency, which makes the poorer trader more aggressive in getting a
favorable deal thus augmenting his winning probabilities. The altruistic
behavior is controlled by varying the number of traders that behave
altruistically and by the degree of altruism that they show. The resulting
wealth distribution is characterized using the Gini index. We compare the
resulting values of the Gini index at different levels of altruism in both
models. It is found that altruistic behavior does lead to a more equitable
wealth distribution but only for unreasonable high values of altruism that are
difficult to expect in a real economic system.Comment: Accepted in Physica A: Statistical Mechanics and its Application
Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus
Coastal lagoons are semi-isolated ecosystems
exposed to wide fluctuations of environmental conditions
and showing habitat fragmentation. These features may
play an important role in separating species into different
populations, even at small spatial scales. In this study, we
evaluate the concordance between mitochondrial (previous
published data) and nuclear data analyzing the genetic
variability of Pomatoschistus marmoratus in five localities,
inside and outside the Mar Menor coastal lagoon (SE
Spain) using eight microsatellites. High genetic diversity
and similar levels of allele richness were observed across
all loci and localities, although significant genic and
genotypic differentiation was found between populations
inside and outside the lagoon. In contrast to the FST values
obtained from previous mitochondrial DNA analyses
(control region), the microsatellite data exhibited significant
differentiation among samples inside the Mar Menor
and between lagoonal and marine samples. This pattern
was corroborated using Cavalli-Sforza genetic distances.
The habitat fragmentation inside the coastal lagoon and
among lagoon and marine localities could be acting as a
barrier to gene flow and contributing to the observed
genetic structure. Our results from generalized additive
models point a significant link between extreme lagoonal
environmental conditions (mainly maximum salinity) and
P. marmoratus genetic composition. Thereby, these environmental
features could be also acting on genetic structure
of coastal lagoon populations of P. marmoratus favoring
their genetic divergence. The mating strategy of P. marmoratus
could be also influencing our results obtained from
mitochondrial and nuclear DNA. Therefore, a special
consideration must be done in the selection of the DNA
markers depending on the reproductive strategy of the
species
High Cyclin E Staining Index in Blastemal, Stromal or Epithelial Cells Is Correlated with Tumor Aggressiveness in Patients with Nephroblastoma
PURPOSE: Identifying among nephroblastoma those with a high propensity for distant metastases using cell cycle markers: cyclin E as a regulator of progression through the cell cycle and Ki-67 as a tumor proliferation marker, since both are often deregulated in many human malignancies. METHODOLOGY/PRINCIPAL FINDINGS: A staining index (SI) was obtained by immunohistochemistry using anti-cyclin E and anti-Ki-67 antibodies in paraffin sections of 54 postchemotherapy nephroblastoma including 42 nephroblastoma without metastasis and 12 with metastases. Median cyclin E and Ki-67 SI were 46% and 33% in blastemal cells, 30% and 10% in stromal cells, 37% and 29.5% in epithelial cells. The highest values were found for anaplastic nephroblastoma. A correlation between cyclin E and Ki-67 SI was found for the blastemal component and for the epithelial component. Univariate analysis showed prognostic significance for metastases with cyclin E SI in stromal cells, epithelial cells and blastemal cells (p = 0.03, p = 0.01 and p = 0.002, respectively) as well as with Ki-67 SI in blastema (p<10(-4)). The most striking data were that both cyclin E SI and blastemal Ki-67 SI discriminated between patients with metastases and patients without metastasis among intermediate-risk nephroblastoma. CONCLUSIONS: Our findings show that a high cyclin E SI in all components of nephroblastoma is correlated with tumor aggressiveness and metastases, and that assessment of its expression may have prognostic value in the categorization of nephroblastoma
How Terrorism Explains Capital Flight from Africa
We assess the effects of terrorism on capital flight in a panel of 29 African countries for which data is available for the period 1987-2008. The terrorism dynamics entail domestic, transnational, unclear and total terrorisms. The empirical evidence is based on Generalised Method of Moments (GMM) with forward orthogonal deviations and Quantile regressions (QR). The following findings are established. First, for GMM, domestic, unclear and total terrorisms consistently increase capital flight, with the magnitude relative higher from unclear terrorism. Second, for QR: (i) the effect of transnational terrorism is now positively significant in the top quantiles (0.75th and 0.90th) of the capital flight distribution, (ii) domestic and total terrorisms are also significant in the top quantiles and (iii) unclear terrorism is significant in the 0.10th and 0.75th quantiles. Policy implications are discussed
CARD15/NOD2 Is Required for Peyer's Patches Homeostasis in Mice
BACKGROUND: CARD15/NOD2 mutations are associated with susceptibility to Crohn's Disease (CD) and Graft Versus Host Disease (GVHD). CD and GVHD are suspected to be related with the dysfunction of Peyer's patches (PP) and isolated lymphoid follicles (LFs). Using a new mouse model invalidated for Card15/Nod2 (KO), we thus analysed the impact of the gene in these lymphoid formations together with the development of experimental colitis. METHODOLOGY/PRINCIPAL FINDINGS: At weeks 4, 12 and 52, the numbers of PPs and LFs were higher in KO mice while no difference was observed at birth. At weeks 4 and 12, the size and cellular composition of PPs were analysed by flow cytometry and immunohistochemistry. PPs of KO mice were larger with an increased proportion of M cells and CD4(+) T-cells. KO mice were also characterised by higher concentrations of TNFalpha, IFNgamma, IL12 and IL4 measured by ELISA. In contrast, little differences were found in the PP-free ileum and the spleen of KO mice. By using chamber experiments, we found that this PP phenotype is associated with an increased of both paracellular permeability and yeast/bacterial translocation. Finally, KO mice were more susceptible to the colitis induced by TNBS. CONCLUSIONS: Card15/Nod2 deficiency induces an abnormal development and function of the PPs characterised by an exaggerated immune response and an increased permeability. These observations provide a comprehensive link between the molecular defect and the Human CARD15/NOD2 associated disorders: CD and GVHD
e-Pilly TROP Maladies infectieuses tropicales
Lâe-Pilly TROP est un ouvrage dâinfectiologie tropicale destinĂ© aux mĂ©decins et aux Ă©tudiants en mĂ©decine des pays francophones du Sud. La prise en compte des diffĂ©rents niveaux de la pyramide sanitaire dans ces pays le rend aussi accessible aux infirmiers des centres de santĂ© communautaires urbains et des structures de santĂ© intermĂ©diaires des zones rurales. Par dĂ©finition, les Pays En DĂ©veloppement accroissant progressivement leurs capacitĂ©s de diagnostic biologique et de traitement, les outils de prise en charge correspondent aux moyens des niveaux pĂ©riphĂ©riques comme Ă ceux des niveaux hospitaliers de rĂ©fĂ©rence
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