Search results for " Migration"
showing 10 items of 754 documents
A Generic Agent-Based Model of Historical Social Behaviors Change
2016
The primary theme of this chapter is trying to describe, discuss and understand how human societies change over time using agent-based modeling. Agents become a major paradigm of social simulation allow us to model the complex social phenomena under the bottom-up approach. Certainly one of the key points of the bottom-up approach is the emergence of macro level phenomena from micro level actions and interactions. The main objective of this work is to build a Virtual Social Laboratory, from Rafael Pla Lopez Social evolution model, in order to explore the social evolution of a set of artificial societies/agents that evolve within a grid of cells which are characterized by a level of natural r…
Age-dependent inbreeding risk and offspring fitness costs in female black grouse
2011
Dispersal is an important mechanism used to avoid inbreeding. However, dispersal may only be effective for part of an individual's lifespan since, post-dispersal individuals that breed over multiple reproductive events may risk mating with kin of the philopatric sex as they age. We tested this hypothesis in black grouse Tetrao tetrix , and show that yearling females never mated with close relatives whereas older females did. However, matings were not with direct kin suggesting that short-distance dispersal to sites containing kin and subsequent overlap of reproductive lifespans between males and females were causing this pattern. Chick mass was lower when kinship was high, suggesting impor…
The aged brain: Genesis and fate of residual progenitor cells in the subventricular zone
2015
Neural stem cells (NSCs) persist in the adult mammalian brain through life. The subventricular zone (SVZ) is the largest source of stem cells in the nervous system, and continuously generates new neuronal and glial cells involved in brain regeneration. During aging, the germinal potential of the SVZ suffers a widespread decline, but the causes of this turn down are not fully understood. This review provides a compilation of the current knowledge about the age-related changes in the NSC population, as well as the fate of the newly generated cells in the aged brain. It is known that the neurogenic capacity is clearly disrupted during aging, while the production of oligodendroglial cells is no…
The Coexistence of Three Species of Daphnia in the Klostersee: iii. The Simulation Model Coda
1991
The population dynamics of three coexisting Daphnia species are described by means of a discrete event simulation model. The model is formulated in the algorithmic language SIMULA which allows very convenient object-oriented programming. Different compartments of a lake are simulated at different levels of integration, each represented by a PROCESS CLASS in SIMULA: The properties of the lake are deposited in a set of meteorological data which were measured in the field. Fish are simulated as a population with properties which are derived from field observations and Daphnia are represented as individuals. The model shows that hypotheses about the stabilizing mechanisms (seasonal change of en…
Mast Cells Induce Migration of Dendritic Cells in a Murine Model of Acute Allergic Airway Disease
2009
<i>Background: </i>The migration of dendritic cells (DCs) from the lungs to the regional lymph nodes is necessary for the development of allergic airway disease. Following activation, mast cells release a variety of stored or de novo-produced inflammatory mediators, several of them being capable of activating DCs. In this study, the role of mast cells on DC migration from the lungs to the thoracic lymph nodes was investigated in sensitized mice. <i>Methods:</i> Mast cell-deficient mice (Kit<sup>W-sh/W-sh</sup>) and their wild-type counterparts were sensitized intraperitoneally with ovalbumine (OVA) in saline and challenged by a single intranasal administr…
Could beta-catenin regulate the expression of proteolitic enzymes during angiogenesis?
2009
During angiogenesis several modifications occurs at endothelial cell plasma membrane level as: MT-MMPs and serine integral membrane proteases (SIMPs) over-expression. Moreover, when endothelial cells during angiogenesis acquired a mesenchymal phenotype the cell-cell interactions mediate by cadherins are lost and β-catenin, a stabilizer of interaction occurring between cadherins and cytoscheleton, can translocate to the nucleus where acts as transcription factor in association to TCF/LEF. Our experiments were focalized to the expression/activation of proteolytic enzymes when cell-cell contacts are perturbed, by mechanical or site specific perturbations. We have analyzed the mRNA, proteins an…
The lipoprotein receptor LRP1 modulates sphingosine-1-phosphate signaling and is essential for vascular development
2014
Low density lipoprotein receptor-related protein 1 (LRP1) is indispensable for embryonic development. Comparing different genetically engineered mouse models, we found that expression of Lrp1 is essential in the embryo proper. Loss of LRP1 leads to lethal vascular defects with lack of proper investment with mural cells of both large and small vessels. We further demonstrate that LRP1 modulates Gi-dependent sphingosine-1-phosphate (S1P) signaling and integrates S1P and PDGF-BB signaling pathways, which are both crucial for mural cell recruitment, via its intracellular domain. Loss of LRP1 leads to a lack of S1P-dependent inhibition of RAC1 and loss of constraint of PDGF-BB-induced cell migra…
Animal Perception of Seasonal Thresholds: Changes in Elephant Movement in Relation to Rainfall Patterns
2012
Background The identification of temporal thresholds or shifts in animal movement informs ecologists of changes in an animal’s behaviour, which contributes to an understanding of species’ responses in different environments. In African savannas, rainfall, temperature and primary productivity influence the movements of large herbivores and drive changes at different scales. Here, we developed a novel approach to define seasonal shifts in movement behaviour by examining the movements of a highly mobile herbivore (elephant; Loxodonta africana), in relation to local and regional rainfall patterns. Methodology/Principal Findings We used speed to determine movement changes of between 8 and 14 GPS…
Macrophage Migration Inhibitory Factor Induces Inflammation and Predicts Spinal Progression in Ankylosing Spondylitis
2017
Objective: To investigate the role of macrophage migration inhibitory factor (MIF) in the pathogenesis of ankylosing spondylitis (AS). Methods: Patients who met the modified New York criteria for AS were recruited for the study. Healthy volunteers, rheumatoid arthritis patients, and osteoarthritis patients were included as controls. Based on the annual rate of increase in modified Stoke AS Spine Score (mSASSS), AS patients were classified as progressors or nonprogressors. MIF levels in serum and synovial fluid were quantitated by enzyme-linked immunosorbent assay. Predictors of AS progression were evaluated using logistic regression analysis. Immunohistochemical analysis of ileal tissue was…
Living in urban interstices: the survival practices of excluded Gypsies in Italian borderlands.
2012
The paper focuses on the case-studies of nomad camps in Italy, where groups of “gypsies” live in condition of ghetto. The nomad camps generally constitute a world out of the city, as an encompassed microcosm. They represent a borderland or a grey zone. The only interaction between “them” and “us” happens when Romanì exit from the camp and cross the municipal streets. Roma people develop a capacity to survive in urban interstices. These practices consist in unusual welfare forms of material help for day by day survival, while living in a condition of human rights negation by majority society members.