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Migration
Kinds of Migration Terms modified by Migration Selected AbstractsMIGRATION, GLOBALISATION AND THE SPIRIT OF PETER BAUERECONOMIC AFFAIRS, Issue 4 2003Daniel T. Griswold Lord Bauer understood that the human freedom of movement plays a vital role in development. Today, internal and cross-border migration generates hard-currency remittances that raise living standards and capital investment in the country of origin, promotes greater trade and investment ties between destination and origin countries, and raises a country's stock of human and physical capital when migrants return with new skills and investment funds. Immigration can also stimulate political and social reform when migrants return or foreign-born immigrants arrive with new ideas and experiences. Relaxing the pervasive controls on the international movement of people remains a huge piece of unfinished business on the market-driven development agenda. [source] RECENT ECOLOGICAL DIVERGENCE DESPITE MIGRATION IN SOCKEYE SALMON (ONCORHYNCHUS NERKA)EVOLUTION, Issue 6 2010Scott A. Pavey Ecological divergence may result when populations experience different selection regimes, but there is considerable discussion about the role of migration at the beginning stages of divergence before reproductive isolating mechanisms have evolved. However, detection of past migration is difficult in current populations and tools to differentiate genetic similarities due to migration versus recent common ancestry are only recently available. Using past volcanic eruption times as a framework, we combine morphological analyses of traits important to reproduction with a coalescent-based genetic analysis of two proximate sockeye salmon (Oncorhynchus nerka) populations. We find that this is the most recent (,500 years, 100 generations) natural ecological divergence recorded in a fish species, and report that this divergence is occurring despite migration. Although studies of fish divergence following the retreat of glaciers (10,000,15,000 years ago) have contributed extensively to our understanding of speciation, the Aniakchak system of sockeye salmon provides a rare example of the initial stages of ecological divergence following natural colonization. Our results show that even in the face of continued migration, populations may diverge in the absence of a physical barrier. [source] CORRELATED EVOLUTION OF MIGRATION AND SEXUAL DICHROMATISM IN THE NEW WORLD ORIOLES (ICTERUS)EVOLUTION, Issue 12 2009Nicholas R. Friedman The evolution of sexual dimorphism has long been attributed to sexual selection, specifically as it would drive repeated gains of elaborate male traits. In contrast to this pattern, New World oriole species all exhibit elaborate male plumage, and the repeated gains of sexual dichromatism observed in the genus are due to losses of female elaboration. Interestingly, most sexually dichromatic orioles belong to migratory or temperate-breeding clades. Using character scoring and ancestral state reconstructions from two recent studies in Icterus, we tested a hypothesis of correlated evolution between migration and sexual dichromatism. We employed two discrete phylogenetic comparative approaches: the concentrated changes test and Pagel's discrete likelihood test. Our results show that the evolution of these traits is significantly correlated (CCT: uncorrected P < 0.05; ML: LRT = 12.470, P < 0.005). Indeed, our best model of character evolution suggests that gains of sexual dichromatism are 23 times more likely to occur in migratory taxa. This study demonstrates that a life-history trait with no direct relationship with sexual selection has a strong influence on the evolution of sexual dichromatism. We recommend that researchers further investigate the role of selection on elaborate female traits in the evolution of sexual dimorphism. [source] EFFECTS OF MIGRATION ON THE GENETIC COVARIANCE MATRIXEVOLUTION, Issue 10 2007Frédéric Guillaume In 1996, Schluter showed that the direction of morphological divergence of closely related species is biased toward the line of least genetic resistance, represented by gmax, the leading eigenvector of the matrix of genetic variance,covariance (the G -matrix). G is used to predict the direction of evolutionary change in natural populations. However, this usage requires that G is sufficiently constant over time to have enough predictive significance. Here, we explore the alternative explanation that G can evolve due to gene flow to conform to the direction of divergence between incipient species. We use computer simulations in a mainland,island migration model with stabilizing selection on two quantitative traits. We show that a high level of gene flow from a mainland population is required to significantly affect the orientation of the G -matrix in an island population. The changes caused by the introgression of the mainland alleles into the island population affect all aspects of the shape of G (size, eccentricity, and orientation) and lead to the alignment of gmax with the line of divergence between the two populations' phenotypic optima. Those changes decrease with increased correlation in mutational effects and with a correlated selection. Our results suggest that high migration rates, such as those often seen at the intraspecific level, will substantially affect the shape and orientation of G, whereas low migration (e.g., at the interspecific level) is unlikely to substantially affect the evolution of G. [source] DIFFERENTIATION AMONG POPULATIONS WITH MIGRATION, MUTATION, AND DRIFT: IMPLICATIONS FOR GENETIC INFERENCEEVOLUTION, Issue 1 2006Seongho Song Abstract Populations may become differentiated from one another as a result of genetic drift. The amounts and patterns of differentiation at neutral loci are determined by local population sizes, migration rates among populations, and mutation rates. We provide exact analytical expressions for the mean, variance, and covariance of a stochastic model for hierarchically structured populations subject to migration, mutation, and drift. In addition to the expected correlation in allele frequencies among populations in the same geographic region, we demonstrate that there is a substantial correlation in allele frequencies among regions at the top level of the hierarchy. We propose a hierarchical Bayesian model for inference of Wright's F -statistics in a two-level hierarchy in which we estimate the among-region correlation in allele frequencies by substituting replication across loci for replication across time. We illustrate the approach through an analysis of human microsatellite data, and we show that approaches ignoring the among-region correlation in allele frequencies underestimate the amount of genetic differentiation among major geographic population groups by approximately 30%. Finally, we discuss the implications of these results for the use and interpretation of F -statistics in evolutionary studies. [source] EVOLUTION OF MIGRATION UNDER KIN SELECTION AND LOCAL ADAPTATIONEVOLUTION, Issue 1 2005Sylvain Billiard Abstract We present here a stochastic two-locus, two-habitat model for the evolution of migration with local adaptation and kin selection. One locus determines the migration rate while the other causes local adaptation. We show that the opposing forces of kin competition and local adaptation can lead to the existence of one or two convergence stable migration rates, notably depending on the recombination rate between the two loci. We show that linkage between migration and local adaptation loci has two antagonist effects: when linkage is tight, cost of local adaptation increases, leading to smaller equilibrium migration rates. However, when linkage is tighter, the population structure at the migration locus tends to be very high because of the indirect selection, and thus equilibrium migration rates increases. This result, qualitatively different from results obtained with other models of migration evolution, indicates that ignoring drift or the detail of the genetic architecture may lead to incorrect conclusions. [source] TIME TO THE MOST RECENT COMMON ANCESTOR AND DIVERGENCE TIMES OF POPULATIONS OF COMMON CHAFFINCHES (FRINGILLA COELEBS) IN EUROPE AND NORTH AFRICA: INSIGHTS INTO PLEISTOCENE REFUGIA AND CURRENT LEVELS OF MIGRATIONEVOLUTION, Issue 1 2002Cortland K. Griswold Abstract We analyzed sequences from a 275-bp hypervariable region in the 5, end of the mitochondrial DNA control region in 190 common chaffinches (Fringilla coelebs) from 19 populations in Europe and North Africa, including new samples from Greece and Morocco. Coalescent techniques were applied to estimate the time to the most recent common ancestor (TMRCA) and divergence times of these populations. The first objective of this study was to infer the locations of refugia where chaffinches survived the last glacial episode, and this was achieved by estimating the TMRCA of populations in regions surrounding the Mediterranean that were unglaciated in the late Pleistocene. Although extant populations in Iberia, Corsica, Greece, and North Africa harbor haplotypes that are basal in a phylogenetic tree, this information alone cannot be used to infer that these localities served as refugia, because it is impossible to infer the ages of populations and their divergence times without also considering the population genetic processes of mutation, migration, and drift. Provided we assume the TMRCAs of populations are a reasonable estimate of a population's age, coalescent-based methods place resident populations in Iberia, Corsica, Greece, and North Africa during the time of the last glacial maximum, suggesting these regions served as refugia for the common chaffinch. The second objective was to determine when populations began diverging from each other and to use this as a baseline to estimate current levels of gene flow. Divergence time estimates suggest that European populations began diverging about 60,000 years before present. The relatively recent divergence of populations in North Africa, Italy, and Iberia may explain why classic migration estimates based on equilibrium assumptions are high for these populations. We compare these estimates with nonequilibrium-based estimates and show that the nonequilibrium estimates are consistently lower than the equilibrium estimates. [source] EVOLUTION OF TEMPORAL ISOLATION IN THE WILD: GENETIC DIVERGENCE IN TIMING OF MIGRATION AND BREEDING BY INTRODUCED CHINOOK SALMON POPULATIONSEVOLUTION, Issue 4 2000Thomas P. Quinn Abstract. The timing of migration and breeding are key life-history traits; they are not only adaptations of populations to their environments, but can serve to increase reproductive isolation, facilitating further divergence among populations. As part of a study of divergence of chinook salmon, Oncorhynchus tshawytscha, populations, established in New Zealand from a common source in the early 1900s, we tested the hypotheses that the timing of migration and breeding are under genetic control and that the populations genetically differ in these traits despite phenotypic overlap in timing in the wild. Representatives of families from two populations were collected within a day or two of each other, reared in a common environment, and then released to sea from each of two different rivers, while other family representatives were retained in fresh water to maturity. The date of maturation of fish held in fresh water and the dates of return from the ocean and maturation of fish released to sea all showed significant differences between the two populations and among families within populations. The very high heritabilities and genetic correlations estimated for migration and maturation date indicated that these traits would respond rapidly to selection. Combined with the results of related studies on these chinook salmon populations, it appears that spawning time may not only evolve during the initial phases of divergence, but it may play an important role in accelerating divergence in other traits. [source] THE INTERSECTIONS OF GENDER AND GENERATION IN ALBANIAN MIGRATION, REMITTANCES AND TRANSNATIONAL CAREGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 1 2009Russell King ABSTRACT. The Albanian case represents the most dramatic instance of post-communist migration: about one million Albanians, a quarter of the country's total population, are now living abroad, most of them in Greece and Italy, with the UK becoming increasingly popular since the late 1990s. This paper draws on three research projects based on fieldwork in Italy, Greece, the UK and Albania. These projects have involved in-depth interviews with Albanian migrants in several cities, as well as with migrant-sending households in different parts of Albania. In this paper we draw out those findings which shed light on the intersections of gender and generations in three aspects of the migration process: the emigration itself, the sending and receiving of remittances, and the care of family members (mainly the migrants' elderly parents) who remain in Albania. Theoretically, we draw on the notion of ,gendered geographies of power' and on how spatial change and separation through migration reshapes gender and generational relations. We find that, at all stages of the migration, Albanian migrants are faced with conflicting and confusing models of gender, behavioural and generational norms, as well as unresolved questions about their legal status and the likely economic, social and political developments in Albania, which make their future life plans uncertain. Legal barriers often prevent migrants and their families from enjoying the kinds of transnational family lives they would like. [source] SIGNIFICANCE OF PASSIVE MIGRATION IN EVOLUTION OF INSECTICIDE RESISTANCE IN THE MOSQUITO CULEX PIPIENS (DIPTERA: CULICIDAE)INSECT SCIENCE, Issue 4 2003Ke Zhang Abstract In order to determine the combined effects of migration and gene flow on evolution of insecticide resistance in the mosquito Culex pipiens, four samples were collected in China, among which two were collected along the railway from Beijing to Guangzhou. Bioassay data showed that the resistance levels of the four populations to dichlorvos were high and to parathion moderate as compared with the susceptible strain and there was no significant difference among the four populations to the same organophosphate (OP) insecticide. Starch electrophoresis was done to identify the frequency of known overproduced esterases and to analyze genetic diversity among various populations by electrophoretic polymorphism of five presumably neutral loci. The results indicated that the gene flow between populations existed and the number of effective migrants (Nm) was related to collection geography (Nm from 1.67 to 40.07). In contrast with lower genetic differentiation between two nearby populations (between GZ and ZS, ZZ and SQ) and higher genetic differentiation between two distant populations (between GZ and ZZ), there was a significant and inconsistent difference in the distribution of resistance alleles, A2-B2 when explained only with active migration. This divergent situation could be straightened out when considering passive migration (such as railway transport) which increased the spread of A2-B2 along the railway, i.e., in GZ and ZZ. The resistance alleles, A2-B2, dispersing to around areas by active migration suffered from the limitation of gene flow and the speed of invasion. [source] MIGRATION: Lucrative Business of Human TraffickingAFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 3 2010Article first published online: 4 MAY 2010 No abstract is available for this article. [source] MIGRATION: Industrialised Countries Cut QuotasAFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 4 2009Article first published online: 4 JUN 200 No abstract is available for this article. [source] PETROLEUM MIGRATION, FAULTS AND OVERPRESSURE, PART I: CALIBRATING BASIN MODELLING USING PETROLEUM IN TRAPS , A REVIEWJOURNAL OF PETROLEUM GEOLOGY, Issue 3 2006D.A. Karlsen This paper considers the principles of deciphering basin-scale hydrocarbon migration patterns using the geochemical information which is present in trapped petroleum. Petroleum accumulations in subsiding basins can be thought of as "data archives" within which stored information can help us to understand aspects of hydrocarbon formation and migration. This information can impart a time-resolved picture of hydrocarbon migration in a basin in response to processes associated with progressive burial, particularly in the context of the occurrence and periodic activity of faults. This review, which includes a series of tentative models of migration-related processes in the extensional Halten Terrace area, offshore mid-Norway, illustrates how we can use information from the migrating mobile hydrocarbon phase to improve our knowledge of the static geological system. Of particular importance is the role of sub-seismic heterogeneities and faults in controlling migration processes. We focus on how the secondary migration process can be enhanced in a multi-source rock basin such as the Halten Terrace, thereby increasing prospectivity. [source] A REVIEW OF GEOLOGICAL DATA THAT CONFLICT WITH THE PARADIGM OF CATAGENIC GENERATION AND MIGRATION OF OILJOURNAL OF PETROLEUM GEOLOGY, Issue 3 2005H. Hugh Wilson The majority of petroleum geologists today agree that the complex problems that surround the origin, generation, migration and accumulation of hydrocarbons can be resolved by accepting the geochemical conclusion that the process originates by catagenic generation in deeply-buried organically-rich source rocks. These limited source rock intervals are believed to expel hydrocarbons when they reach organic maturity in oil kitchens. The expelled oil and gas then follow migration pathways to traps at shallower levels. However, there are major geological obstacles that cast doubt upon this interpretation. The restriction of the source rock to a few organically rich levels in a basin forces the conclusion that the basin plumbing system is leaky and allows secondary horizontal and vertical migration through great thicknesses of consolidated sedimentary rocks in which there are numerous permeability barriers that are known to effectively prevent hydrocarbon escape from traps. The sourcing of lenticular traps points to the enclosing impermeable envelope as the logical origin of the trapped hydrocarbons. The lynch-pin of the catagenic theory of hydrocarbon origin is the expulsion mechanism from deeply-buried consolidated source rock under high confining pressures. This mechanism is not understood and is termed an "enigma". Assuming that expulsion does occur, the pathways taken by the hydrocarbons to waiting traps can be ascertained by computer modelling of the basin. However, subsurface and field geological support for purported migration pathways has yet to be provided. Many oilfield studies have shown that oil and gas are preferentially trapped in synchronous highs that were formed during, or very shortly after, the deposition of the charged reservoir. An unresolved problem is how catagenically generated hydrocarbons, expelled during a long-drawn-out maturation period, can have filled synchronous highs but have avoided later traps along the assumed migration pathways. From many oilfield studies, it has also been shown that the presence of hydrocarbons inhibits diagenesis and compaction of the reservoir rock. This "Füchtbauer effect" points to not only the early charging of clastic and carbonate reservoirs, but also to the development of permeability barriers below the early-formed accumulations. These barriers would prevent later hydrocarbon additions during the supposed extended period of expulsion from an oil kitchen. Early-formed traps that have been sealed diagenetically will retain their charge even if the trap is opened by later structural tilting. Diagenetic traps have been discovered in clastic and carbonate provinces but their recognition as viable exploration targets is discouraged by present-day assumptions of late hydrocarbon generation and a leaky basin plumbing system. Because there are so many geological realities that cast doubt upon the assumptions that devolve from the paradigm of catagenic generation, the alternative concept of early biogenic generation and accumulation of immature oil, with in-reservoir cracking during burial, is again worthy of serious consideration. This concept envisages hydrocarbon generation by bacterial activity in many anoxic environments and the charging of synchronous highs from adjacent sources. The resolution of the fundamental problem of hydrocarbon generation and accumulation, which is critical to exploration strategies, should be sought in the light of a thorough knowledge of the geologic factors involved, rather than by computer modelling which may be guided by questionable geochemical assumptions. [source] COLLEGE-TO-WORK MIGRATION OF TECHNOLOGY GRADUATES AND HOLDERS OF DOCTORATES WITHIN THE UNITED STATESJOURNAL OF REGIONAL SCIENCE, Issue 4 2006Paul D. Gottlieb ABSTRACT This study estimates a series of random parameter logit models of the college-to-work migration decisions of technology graduates and holders of doctorates within the United States. We employ detailed information on the migration-relevant characteristics of individuals, as well as on their actual origins and destinations at the metropolitan scale. In addition to its obvious implications for "brain drain" policies in U.S. metropolitan areas, the study demonstrates the richness of the random parameters technique for behavioral-geographic analysis. We find that science and technology graduates migrate to better educated places, other things equal; that PhD graduates pay greater attention to amenity characteristics than other degree holders; and that foreign students from some immigrant groups migrate to places where those groups are concentrated. [source] SWIMMING SPEEDS OF SINGING AND NON-SINGING HUMPBACK WHALES DURING MIGRATIONMARINE MAMMAL SCIENCE, Issue 3 2007Michael J. Noad Abstract Limited data exist on swimming speeds of humpback whales (Megaptera novaeangliae) and none on swimming speeds of singing whales during migration. We tracked humpback whales visually and acoustically during migration from the breeding grounds past our study site on the east coast of Australia (latitude 26°28,S). The mean swimming speed for whales while singing was 2.5 km/h, significantly less than for non-singing whales with a mean of 4.0 km/h but significantly greater than the mean of 1.6 km/h observed for singing whales on the Hawaiian breeding grounds. Between song sessions, there was no significant difference in speeds between whales that had been singing and other whales. Migration speeds were less for whales while singing but increased during the season. Although humpback whales can swim rapidly while singing (maximum observed 15.6 km/h), they generally do not do so, even during migration. Slower migration by singers would delay their return to the polar feeding areas and may be costly, but may be a strategy to provide access to more females. [source] COORDINATION FAILURES IN NETWORK MIGRATION,THE MANCHESTER SCHOOL, Issue 6 2006AXEL HEITMUELLER Previous immigration facilitates future immigration, a phenomenon called network migration. While well recognized, previous research has mainly focused on the implications of immigrant networks on future migrants. In contrast, this paper derives a simple model from the perspective of the incumbent immigrant population by introducing sub-networks and argues that the incumbent migrants fail to achieve a Pareto optimal network size due to differences in inter- and intra-migrant group externalities and subsequently coordination failures. In short, it stresses the active role incumbents take in the provision of network effects and provides theoretical evidence that self-perpetuating and sustained immigration is not at odds with rational acting individuals. It also shows that optimally chosen migration quotas may appeal to incumbent migration cohorts and provides an alternative explanation for inter- and intra-migrant group tensions. [source] MIGRATION, MEDICAL AID AND WELFARE*AUSTRALIAN ECONOMIC PAPERS, Issue 4 2007WATARU KUREISHI This paper constructs a simple rural-urban migration model that explicitly incorporates the interactions between the individual's migration decision, the risk of incurring an infectious disease and unemployment. We show that providing a subsidy for health investment in urban regions in the form of medical aid does not improve individual welfare. This is because it induces further urban migration, increases the risk of infection and unemployment, and offsets completely the positive cost-reduction effect. [source] PIOGLITAZONE INHIBITS HOMOCYSTEINE-INDUCED MIGRATION OF VASCULAR SMOOTH MUSCLE CELLS THROUGH A PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR ,-INDEPENDENT MECHANISMCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2008Li Li SUMMARY 1Peroxisome proliferator-activated receptor (PPAR)-, agonists have been demonstrated to exert protective effects against homocysteine (Hcy)-induced pathogenesis. However, the effects of PPAR-, agonists on Hcy-induced migration are unknown. In the present study, we examined the effect of pioglitazone on the migration of vascular smooth muscle cells (VSMC) induced by Hcy and the possible mechanism involved. 2Vascular smooth muscle cells were isolated from the thoracic aortas of male Sprague-Dawley rats. The migration of VSMC was examined using a transwell technique. The generation of intracellular reactive oxygen species (ROS) was measured using the ROS-sensitive fluoroprobe 2,,7,-dichlorodihydrofluorescein diacetate. The activity of NAD(P)H oxidase was assessed by lucigenin enhanced chemiluminescence. Activation of p38 mitogen-activated protein kinase (MAPK) was determined by western blotting. 3The results showed that pioglitazone dose-dependently inhibited the migration of VSMC induced by Hcy. This was not reversed by the PPAR-, antagonist GW9662. In addition, pretreatment with the NAD(P)H oxidase inhibitor diphenylene iodonium (DPI), the free radical scavenger N -acetylcysteine and the p38 MAPK inhibitor SB202190 blocked Hcy-induced VSMC migration. Furthermore, we observed that pioglitazone suppressed Hcy-induced intracellular ROS production; similar effects were observed with DPI and NAC. Pioglitazone attenuated Hcy-induced activation of NAD(P)H oxidase. Moreover, pioglitazone blocked Hcy-induced p38 MAPK phosphorylation; similar effects were observed for DPI, NAC and SB202190. 4The data demonstrate that pioglitazone inhibits Hcy-induced VSMC migration that is independent of PPAR-,. Furthermore, part of the biological effect of pioglitazone involves a decrease in the levels of NAD(P)H oxidase derived-ROS and p38 MAPK activation. [source] AUTOMATICALLY OPERATING RADARS FOR MONITORING INSECT PEST MIGRATIONSINSECT SCIENCE, Issue 4 2002Alistair Drake Abstract, Over the last three decades, special-purpose "entomological" radars have contributed much to the development of our understanding of insect migration, especially of the nocturnal migrations at altitudes of up to , 1 km that are regularly undertaken by many important pest species. One of the limitations of early radar studies, the difficulty of maintaining observations over long periods, has recently been overcome by the development of automated units that operate autonomously and transmit summaries of their observations to a base laboratory over the public telephone network. These relatively low-cost Insect Monitoring Radars (IMRs) employ a novel "ZLC" configuration that allows high quality data on the migrants' flight parameters and identity to be acquired. Two IMRs are currently operating in the semi-arid inland of eastern Australia, in a region where populations of migrant moths (Lepidoptera) and Australian plague locusts Chortoicetes terminifera (Orthoptera) commonly originate, and some examples of outputs from one of these units are presented. IMRs are able to provide the data needed to characterize a migration system, i.e. to estimate the probabilities of migration events occurring in particular directions at particular seasons and in response to particular environmental conditions and cues. They also appear capable of fulfilling a "sentinel" role for pest-management organisations, alerting forecasters to major migration events and thus to the likely new locations of potential target populations. Finally, they may be suitable for a more general ecological monitoring role, perhaps especially for quantifying year-to-year variations in biological productivity. [source] THE INAUGURAL NOEL BUTLIN LECTURE: WORLD FACTOR MIGRATIONS AND DEMOGRAPHIC TRANSITIONSAUSTRALIAN ECONOMIC HISTORY REVIEW, Issue 2 2004Jeffrey G. Williamson This lecture explores the connection between demographic transitions, mass migrations and international capital flows. It reviews how demographic transitions influence the size of age cohorts, and then how these changes in age distribution influence excess demands in receiving regions and excess supplies in sending regions. The lecture offers four examples , two from the first global century and two from the second global century , where shocks generated by demographic transitions have had an enormous impact on factor flows: European mass migrations to the New World before 1914; African mass migrations to the OECD over the past two decades; British capital export to the New World before 1914; and capital flows across East Asian borders after 1950 and before the melt down of the 1990s. The lecture concludes with an assessment of the demographic contribution to the East Asian miracle (and slowdown) over the past half century. [source] Reparallelization techniques for migrating OpenMP codes in computational gridsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 3 2009Michael Klemm Typical computational grid users target only a single cluster and have to estimate the runtime of their jobs. Job schedulers prefer short-running jobs to maintain a high system utilization. If the user underestimates the runtime, premature termination causes computation loss; overestimation is penalized by long queue times. As a solution, we present an automatic reparallelization and migration of OpenMP applications. A reparallelization is dynamically computed for an OpenMP work distribution when the number of CPUs changes. The application can be migrated between clusters when an allocated time slice is exceeded. Migration is based on a coordinated, heterogeneous checkpointing algorithm. Both reparallelization and migration enable the user to freely use computing time at more than a single point of the grid. Our demo applications successfully adapt to the changed CPU setting and smoothly migrate between, for example, clusters in Erlangen, Germany, and Amsterdam, the Netherlands, that use different kinds and numbers of processors. Benchmarks show that reparallelization and migration impose average overheads of about 4 and 2%, respectively. Copyright © 2008 John Wiley & Sons, Ltd. [source] A Case of Aptos Thread Migration and Partial ExpulsionDERMATOLOGIC SURGERY, Issue 3 2005José G. Silva-Siwady MD Background In our practice, the use of dented polypropylene suture has become a very simple, conservative, and effective procedure for lifting flabby ptosed facial tissue, improving it without surgery. As with some cosmetic procedures, we have seen complications with this technique. Objective To present a case report of migration and partial expulsion of Aptos thread (TOTAL Charm, Moscow, Russia). Methods After successful fixation of facial tissue with 10 Aptos threads (5 on each side, 3 in the upper and central cheek, and 2 in the mandibular area), the patient returned 28 days later owing to migration and partial expulsion of one of the Aptos threads. Results The expulsed thread was easily removed, and the patient was treated with antibiotic therapy without further complications. Conclusion After this experience, we can conclude that Aptos threads are an additional tool in our arsenal for the treatment of facial aging. We must be especially cautious and aware that our patients can present with previously unknown complications secondary to newly described procedures, as with this recent technique. JOSé G. SILVA-SIWADY, MD, CELINA DÍAZ-GARZA, AND JORGE OCAMPO-CANDIANI, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source] ,The Perfect Business': Human Trafficking and Lao,Thai Cross-Border MigrationDEVELOPMENT AND CHANGE, Issue 5 2010Sverre Molland ABSTRACT Over the past few years some governments and development organizations have increasingly articulated cross-border mobility as ,trafficking in persons'. The notion of a,market,where traffickers prey on the ,supply' of migrants that flows across international borders to meet the ,demand' for labour has become a central trope among anti-trafficking development organizations. This article problematizes such,economism,by drawing attention to the oscillating cross-border migration of Lao sex workers within a border zone between Laos and Thailand. It illuminates the incongruity between the recruitment of women into the sex industry along the Lao,Thai border and the market models that are employed by the anti-trafficking sector. It discusses the ways in which these cross-border markets are conceived in a context where aid programming is taking on an increasingly important role in the politics of borders. The author concludes that allusions to ideal forms of knowledge (in the guise of classic economic theory) and an emphasis on borders become necessary for anti-trafficking programmes in order to make their object of intervention legible as well as providing post-hoc rationalizations for their continuing operation. [source] Struggling to Save Cash: Seasonal Migration and Vulnerability in West Bengal, IndiaDEVELOPMENT AND CHANGE, Issue 4 2003Ben Rogaly This article concerns an important but overlooked means by which able-bodied poor people get hold of lump sums of cash in rural West Bengal: seasonal migration for agricultural wage work. Drawing on a regional study of four migration streams, our main focus here is on the struggle to secure this cash by landless households in just one of those streams, originating in Murshidabad District. Case studies are used to illustrate the importance for women in nuclear families of maintaining supportive networks of kin for periods when men are absent. A parallel analysis is made of the negotiations between male migrant workers and their employers, at labour markets, during the period of work, and afterwards. The article then briefly discusses some of the contrasting ways in which remittances are used by landless households and owners of very small plots of land, in the context of rapid ecological change, demographic pressure and growing inequality. [source] Migration of mesenchymal cell fated to blastema is necessary for fish fin regenerationDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 2 2008Yuki Nakatani Urodeles and fish have higher regeneration ability in a variety of tissues and organs than do other vertebrate species including mammals. Though many studies have aimed at identifying the cellular and molecular basis for regeneration, relatively little is known about the detailed cellular behaviors and involved molecular basis. In the present study, a small molecule inhibitor was used to analyzed the role of phosphoinositide 3-kinase (PI3K) signaling during regeneration. We showed that the inhibitor disrupted the formation of blastema including the expression of characteristic genes. The failure of blastema formation was due to the impaired migration of mesenchymal cells to the distal prospective blastema region, although it had a little affect on cell cycle activation in mesenchymal cells. Moreover, we found that the epidermal remodeling including cell proliferation, distal cell migration and Akt phosphorylation was also affected by the inhibitor, implying a possible involvement of epidermis for proper formation of blastema. From these data, we propose a model in which distinct signals that direct the cell cycle activation, mesenchymal cell migration and epidermal remodeling coordinate together to accomplish the correct blastema formation and regeneration. [source] Reelin is essential for neuronal migration but not for radial glial elongation in neonatal ferret cortex,DEVELOPMENTAL NEUROBIOLOGY, Issue 5 2008Alisa Schaefer Abstract Numerous functions related to neuronal migration are linked to the glycoprotein reelin. Reelin also elongates radial glia, which are disrupted in mutant reeler mice. Our lab developed a model of cortical dysplasia in ferrets that shares features with the reeler mouse, including impaired migration of neurons into the cerebral cortex and disrupted radial glia. Explants of normal ferret cortex in coculture with dysplastic ferret cortex restore the deficits in this model. To determine if reelin is integral to the repair, we used explants of P0 mouse cortex either of the wild type (WT) or heterozygous (het) for the reelin gene, as well as P0 reeler cortex (not containing reelin), in coculture with organotypic cultures of dysplastic ferret cortex. This arrangement revealed that all types of mouse cortical explants (WT, het, reeler) elongated radial glia in ferret cortical dysplasia, indicating that reelin is not required for proper radial glial morphology. Migration of cells into ferret neocortex, however, did not improve with explants of reeler cortex, but was almost normal after pairing with WT or het explants. We also placed an exogenous source of reelin in ferret cultures at the pial surface to reveal that migrating cells move toward the reelin source in dysplastic cortex; radial glia in these cultures were also improved toward normal. Our results demonstrate that the normotopic position of reelin is important for proper neuronal positioning, and that reelin is capable of elongating radial glial cells but is not the only radialization factor. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008. [source] Migration of hawksbill turtles Eretmochelys imbricata from Tortuguero, Costa RicaECOGRAPHY, Issue 3 2005Sebastian Troëng The hawksbill turtle Eretmochelys imbricata is a widely distributed and critically endangered species that feeds on sponges and fills an important ecological role in the coral reef ecosystem. At Tortuguero, Costa Rica, trend analyses indicate considerable decline in nesting estimated at 77.2,94.5% between 1956 and 2003, as a result of excessive turtle fishing. We analyzed flipper tag returns, satellite telemetry and genetic samples to determine movements and habitat use of adult female Tortuguero hawksbills. Tag returns and satellite telemetry show hawksbills migrate to foraging grounds in Nicaragua and Honduras. Genetic analysis indicates the hawksbills may also migrate to Cuban, Puerto Rican, and possibly Mexican waters. We conclude hawksbills represent an internationally shared resource. There is a close correlation between tag recapture sites, hawksbill foraging grounds and coral reef distribution. Caribbean coral reef decline may reduce food availability and negatively impact hawksbill turtles. Conversely, hawksbill decline may shift the balance on coral reefs by reducing predation pressure on sponges and hence make coral reefs less resilient to natural and anthropogenic threats. Strategies aiming to conserve hawksbills and coral reefs must consider both the extensive hawksbill migrations and the close relationship between the species and the coral reef ecosystem. [source] Migration of landlocked brown trout in two Scandinavian streams as revealed from trap dataECOLOGY OF FRESHWATER FISH, Issue 3 2004J. Carlsson Abstract,,, Anthropogenic barriers that may interfere or prevent fish migration are commonly found in streams throughout the distribution of salmonids. Construction of fish passages in streams is a common solution to this problem. However, the goal with fish passages is often, at least in Scandinavia, to allow Atlantic salmon (Salmo salar L.) and migratory brown trout (S. trutta L.) to get access to spawning areas above these barriers. Hence, the fish passages may often only be open during the spawning migration of salmonids (late summer to autumn). We present data, on wild brown trout migration, from two trapping systems in two Scandinavian streams showing that intra- and interstream migrations are common throughout the summer and autumn. Moreover, differences in size were found between trap-caught trout and electrofished trout where trapped trout were generally larger than electrofished trout. We suggest that the current regime with fish passages only open parts of the year can have negative effects on populations by depriving trout from the possibility to perform migrations throughout the year. Resumen 1. Barreras de origin antrópico que pueden interferer o prevenir las migraciones de los peces son frecuentes a lo largo de las áreas de distribución de los salmónidos. Una solución común a este problema es la construcción de pasos. Si embargo, el fin general de estos pasos es, por lo menos en Escandinavia, permitir el acceso a las áreas de reproducción por encima de las barreras tanto a salmones (Salmo salar L.) como a truchas migratorias (S. trutta L.). Frecuentemente, estos pasos están solamente abiertos durante el período de migración reproductiva (final del verano y otoño) porque se piensa que este régimen no tiene consecuencias negativas ya que estas especies muestran movimientos muy limitados en otros periodos del año. 2. Presentamos datos sobre migraciones de truchas colectados en dos sistemas de trampas de dos ríos escandinavos. Un río localizado por encima de una catarata inaccesible. El segundo, con una población migratoria de truchas. Los datos indicaron claramente migraciones intensivas a lo largo de todo el período en el que las trampas estuvieron operativas. Ambos ríos mostraron un pico de migración aguas arriba a mediados de Julio. Migraciones aguas abajo fueron raramente observadas en la población por encima de la catarata aunque migraciones aguas abajo en la población del río fueron intensivas al final del otoño. 3. Sugerimos que el régimen actual de pasos de peces que abren solamente partes del año puede tener efectos negativos sobre las poblaciones, al privar a las truchas de la posibilidad de migrar a lo largo del año. Esto puede extenderse a otros sistemas con barreras ya que observamos también migraciones intensivas en la población localizada por encima de la catarata. [source] The effects of fluvial processes and habitat heterogeneity on distribution, growth and densities of juvenile Atlantic salmon (Salmo salar L.), with consequences on abundance of the adult fishECOLOGY OF FRESHWATER FISH, Issue 4 2002R. J. Gibson Abstract,,,The required freshwater habitats of juvenile Atlantic salmon (Salmo salar) are, in general, well known, but vary in quality, related to interacting effects of several variables, which may depend on different parts of a river system. Examples are given of ranges of densities and growth that can be found at various sites in eastern Canada, illustrating the biological and physico-chemical factors affecting production of juvenile salmon. Relative growth rates can indicate habitat quality and population densities. Salmon parr have negative effects on brook trout in riffle habitats. The effects of migrations within the river and of changes with stream succession on juvenile salmon production are illustrated with examples from a Newfoundland river. Migration of age-classes can be quantified from ,self-thinning' curves. Lakes have enhancing effects on downstream fluvial habitats, and, at least in Newfoundland, and probably in many boreal areas, the lacustrine proportion of the basin can be used as an index for deriving estimates of required spawning escapement. The factors described should be taken into account for more refined estimates of river production and management of the salmon resource. [source] | ||||||||||||||||||||||||||||||||||||||||||||||