Science.gov

Sample records for range-wide demographic expansion

  1. Range-wide multilocus phylogeography of the red fox reveals ancient continental divergence, minimal genomic exchange and distinct demographic histories.

    PubMed

    Statham, Mark J; Murdoch, James; Janecka, Jan; Aubry, Keith B; Edwards, Ceiridwen J; Soulsbury, Carl D; Berry, Oliver; Wang, Zhenghuan; Harrison, David; Pearch, Malcolm; Tomsett, Louise; Chupasko, Judith; Sacks, Benjamin N

    2014-10-01

    Widely distributed taxa provide an opportunity to compare biogeographic responses to climatic fluctuations on multiple continents and to investigate speciation. We conducted the most geographically and genomically comprehensive study to date of the red fox (Vulpes vulpes), the world's most widely distributed wild terrestrial carnivore. Analyses of 697 bp of mitochondrial sequence in ~1000 individuals suggested an ancient Middle Eastern origin for all extant red foxes and a 400 kya (SD = 139 kya) origin of the primary North American (Nearctic) clade. Demographic analyses indicated a major expansion in Eurasia during the last glaciation (~50 kya), coinciding with a previously described secondary transfer of a single matriline (Holarctic) to North America. In contrast, North American matrilines (including the transferred portion of Holarctic clade) exhibited no signatures of expansion until the end of the Pleistocene (~12 kya). Analyses of 11 autosomal loci from a subset of foxes supported the colonization time frame suggested by mtDNA (and the fossil record) but, in contrast, reflected no detectable secondary transfer, resulting in the most fundamental genomic division of red foxes at the Bering Strait. Endemic continental Y-chromosome clades further supported this pattern. Thus, intercontinental genomic exchange was overall very limited, consistent with long-term reproductive isolation since the initial colonization of North America. Based on continental divergence times in other carnivoran species pairs, our findings support a model of peripatric speciation and are consistent with the previous classification of the North American red fox as a distinct species, V. fulva. PMID:25212210

  2. Mitochondrial DNA signature for range-wide populations of Bicyclus anynana suggests a rapid expansion from recent refugia.

    PubMed

    de Jong, Maaike A; Wahlberg, Niklas; van Eijk, Marleen; Brakefield, Paul M; Zwaan, Bas J

    2011-01-01

    This study investigates the genetic diversity, population structure and demographic history of the afrotropical butterfly Bicyclus anynana using mitochondrial DNA (mtDNA). Samples from six wild populations covering most of the species range from Uganda to South Africa were compared for the cytochrome c oxidase subunit gene (COI). Molecular diversity indices show overall high mtDNA diversity for the populations, but low nucleotide divergence between haplotypes. Our results indicate relatively little geographic population structure among the southern populations, especially given the extensive distributional range and an expectation of limited gene flow between populations. We implemented neutrality tests to assess signatures of recent historical demographic events. Tajima's D test and Fu's F(S) test both suggested recent population growth for the populations. The results were only significant for the southernmost populations when applying Tajima's D, but Fu's F(S) indicated significant deviations from neutrality for all populations except the one closest to the equator. Based on our own findings and those from pollen and vegetation studies, we hypothesize that the species range of B. anynana was reduced to equatorial refugia during the last glacial period, and that the species expanded southwards during the past 10.000 years. These results provide crucial background information for studies of phenotypic and molecular adaptation in wild populations of B. anynana. PMID:21731725

  3. Targeted Capture Sequencing in Whitebark Pine Reveals Range-Wide Demographic and Adaptive Patterns Despite Challenges of a Large, Repetitive Genome.

    PubMed

    Syring, John V; Tennessen, Jacob A; Jennings, Tara N; Wegrzyn, Jill; Scelfo-Dalbey, Camille; Cronn, Richard

    2016-01-01

    Whitebark pine (Pinus albicaulis) inhabits an expansive range in western North America, and it is a keystone species of subalpine environments. Whitebark is susceptible to multiple threats - climate change, white pine blister rust, mountain pine beetle, and fire exclusion - and it is suffering significant mortality range-wide, prompting the tree to be listed as 'globally endangered' by the International Union for Conservation of Nature and 'endangered' by the Canadian government. Conservation collections (in situ and ex situ) are being initiated to preserve the genetic legacy of the species. Reliable, transferrable, and highly variable genetic markers are essential for quantifying the genetic profiles of seed collections relative to natural stands, and ensuring the completeness of conservation collections. We evaluated the use of hybridization-based target capture to enrich specific genomic regions from the 27 GB genome of whitebark pine, and to evaluate genetic variation across loci, trees, and geography. Probes were designed to capture 7,849 distinct genes, and screening was performed on 48 trees. Despite the inclusion of repetitive elements in the probe pool, the resulting dataset provided information on 4,452 genes and 32% of targeted positions (528,873 bp), and we were able to identify 12,390 segregating sites from 47 trees. Variations reveal strong geographic trends in heterozygosity and allelic richness, with trees from the southern Cascade and Sierra Range showing the greatest distinctiveness and differentiation. Our results show that even under non-optimal conditions (low enrichment efficiency; inclusion of repetitive elements in baits), targeted enrichment produces high quality, codominant genotypes from large genomes. The resulting data can be readily integrated into management and gene conservation activities for whitebark pine, and have the potential to be applied to other members of 5-needle pine group (Pinus subsect. Quinquefolia) due to their

  4. Targeted Capture Sequencing in Whitebark Pine Reveals Range-Wide Demographic and Adaptive Patterns Despite Challenges of a Large, Repetitive Genome

    PubMed Central

    Syring, John V.; Tennessen, Jacob A.; Jennings, Tara N.; Wegrzyn, Jill; Scelfo-Dalbey, Camille; Cronn, Richard

    2016-01-01

    Whitebark pine (Pinus albicaulis) inhabits an expansive range in western North America, and it is a keystone species of subalpine environments. Whitebark is susceptible to multiple threats – climate change, white pine blister rust, mountain pine beetle, and fire exclusion – and it is suffering significant mortality range-wide, prompting the tree to be listed as ‘globally endangered’ by the International Union for Conservation of Nature and ‘endangered’ by the Canadian government. Conservation collections (in situ and ex situ) are being initiated to preserve the genetic legacy of the species. Reliable, transferrable, and highly variable genetic markers are essential for quantifying the genetic profiles of seed collections relative to natural stands, and ensuring the completeness of conservation collections. We evaluated the use of hybridization-based target capture to enrich specific genomic regions from the 27 GB genome of whitebark pine, and to evaluate genetic variation across loci, trees, and geography. Probes were designed to capture 7,849 distinct genes, and screening was performed on 48 trees. Despite the inclusion of repetitive elements in the probe pool, the resulting dataset provided information on 4,452 genes and 32% of targeted positions (528,873 bp), and we were able to identify 12,390 segregating sites from 47 trees. Variations reveal strong geographic trends in heterozygosity and allelic richness, with trees from the southern Cascade and Sierra Range showing the greatest distinctiveness and differentiation. Our results show that even under non-optimal conditions (low enrichment efficiency; inclusion of repetitive elements in baits), targeted enrichment produces high quality, codominant genotypes from large genomes. The resulting data can be readily integrated into management and gene conservation activities for whitebark pine, and have the potential to be applied to other members of 5-needle pine group (Pinus subsect. Quinquefolia) due to

  5. Range-wide success of red-cockaded woodpecker translocations.

    SciTech Connect

    Edwards, John W.; Costa, Ralph

    2004-12-31

    Edwards, John W.; Costa, Ralph. 2004. Range-wide success of red-cockaded woodpecker translocations. In: Red-cockaded woodpecker; Road to Recovery. Proceedings of the 4th Red-cockaded woodpecker Symposium. Ralph Costa and Susan J. Daniels, eds. Savannah, Georgia. January, 2003. Chapter 6. Translocation. Pp 307-311. Abstract: Red-cockaded woodpeckers (Picoides borealis) have declined range-wide during the past century, suffering from habitat loss and the effects of fire exclusion in older southern pine forests. Red-cockaded woodpecker translocations are a potentially important tool in conservation efforts to reestablish red-cockaded woodpeckers in areas from which they have been extirpated. Currently, translocations are critical in ongoing efforts to save and restore the many existing small populations. We examined the effects of demographic and environmental factors on the range-wide success of translocations between 1989 and 1995.

  6. Molecular evidence for a recent demographic expansion in the puma (Puma concolor) (Mammalia, Felidae)

    PubMed Central

    Matte, Eunice M.; Castilho, Camila S.; Miotto, Renata A.; Sana, Denis A.; Johnson, Warren E.; O’Brien, Stephen J.; de Freitas, Thales R. O.; Eizirik, Eduardo

    2013-01-01

    The puma is an iconic predator that ranges throughout the Americas, occupying diverse habitats. Previous phylogeographic analyses have revealed that it exhibits moderate levels of genetic structure across its range, with few of the classically recognized subspecies being supported as distinct demographic units. Moreover, most of the species’ molecular diversity was found to be in South America. To further investigate the phylogeographic structure and demographic history of pumas we analyzed mtDNA sequences from 186 individuals sampled throughout their range, with emphasis on South America. Our objectives were to refine the phylogeographic assessment within South America and to investigate the demographic history of pumas using a coalescent approach. Our results extend previous phylogeographic findings, reassessing the delimitation of historical population units in South America and demonstrating that this species experienced a considerable demographic expansion in the Holocene, ca. 8,000 years ago. Our analyses indicate that this expansion occurred in South America, prior to the hypothesized re-colonization of North America, which was therefore inferred to be even more recent. The estimated demographic history supports the interpretation that pumas suffered a severe demographic decline in the Late Pleistocene throughout their distribution, followed by population expansion and re-colonization of the range, initiating from South America. PMID:24385863

  7. Molecular evidence for a recent demographic expansion in the puma (Puma concolor) (Mammalia, Felidae).

    PubMed

    Matte, Eunice M; Castilho, Camila S; Miotto, Renata A; Sana, Denis A; Johnson, Warren E; O'Brien, Stephen J; de Freitas, Thales R O; Eizirik, Eduardo

    2013-12-01

    The puma is an iconic predator that ranges throughout the Americas, occupying diverse habitats. Previous phylogeographic analyses have revealed that it exhibits moderate levels of genetic structure across its range, with few of the classically recognized subspecies being supported as distinct demographic units. Moreover, most of the species' molecular diversity was found to be in South America. To further investigate the phylogeographic structure and demographic history of pumas we analyzed mtDNA sequences from 186 individuals sampled throughout their range, with emphasis on South America. Our objectives were to refine the phylogeographic assessment within South America and to investigate the demographic history of pumas using a coalescent approach. Our results extend previous phylogeographic findings, reassessing the delimitation of historical population units in South America and demonstrating that this species experienced a considerable demographic expansion in the Holocene, ca. 8,000 years ago. Our analyses indicate that this expansion occurred in South America, prior to the hypothesized re-colonization of North America, which was therefore inferred to be even more recent. The estimated demographic history supports the interpretation that pumas suffered a severe demographic decline in the Late Pleistocene throughout their distribution, followed by population expansion and re-colonization of the range, initiating from South America. PMID:24385863

  8. Genetic footprints of demographic expansion in North America, but not Amazonia, during the Late Quaternary.

    PubMed

    Lessa, Enrique P; Cook, Joseph A; Patton, James L

    2003-09-01

    The biotic consequences of climate change have attracted considerable attention. In particular, the "refugial debate" centers on the possible retraction of habitats to limited areas that may have served as refuges for many associated species, especially during glaciations of the Quaternary. One prediction of such scenarios is that populations must have experienced substantial growth accompanying climatic amelioration and the occupation of newly expanded habitats. We used coalescence theory to examine the genetic evidence, or lack thereof, for late Pleistocene refugia of boreal North American and tropical Amazonian mammals. We found substantial and concordant evidence of demographic expansion in North American mammals, particularly at higher latitudes. In contrast, small mammals from western Amazonia appear to have experienced limited or no demographic expansion after the Late Pleistocene. Thus, demographic responses to climate change can be tracked genetically and appear to vary substantially across the latitudinal gradient of biotic diversity. PMID:12913123

  9. Why hunter-gatherer populations do not show signs of Pleistocene demographic expansions

    PubMed Central

    Excoffier, Laurent; Schneider, Stefan

    1999-01-01

    The mitochondrial DNA diversity of 62 human population samples was examined for potential signals of population expansions. Stepwise expansion times were estimated by taking into account heterogeneity of mutation rates among sites. Assuming an mtDNA divergence rate of 33% per million years, most populations show signals of Pleistocene expansions at around 70,000 years (70 KY) ago in Africa and Asia, 55 KY ago in America, and 40 KY ago in Europe and the Middle East, whereas the traces of the oldest expansions are found in East Africa (110 KY ago for the Turkana). The genetic diversity of two groups of populations (most Amerindian populations and present-day hunter-gatherers) cannot be explained by a simple stepwise expansion model. A multivariate analysis of the genetic distances among 61 populations reveals that populations that did not undergo demographic expansions show increased genetic distances from other populations, confirming that the demography of the populations strongly affects observed genetic affinities. The absence of traces of Pleistocene expansions in present-day hunter-gatherers seems best explained by the occurrence of recent bottlenecks in those populations, implying a difference between Pleistocene (≈1,800 KY to 10 KY ago) and Holocene (10 KY to present) hunter-gatherers demographies, a difference that occurred after, and probably in response to, the Neolithic expansions of the other populations. PMID:10485871

  10. Late Glacial Demographic Expansion Motivates a Clock Overhaul for Population Genetics.

    PubMed

    Hoareau, Thierry B

    2016-05-01

    The molecular clock hypothesis is fundamental in evolutionary biology as by assuming constancy of the molecular rate it provides a timeframe for evolution. However, increasing evidence shows time dependence of inferred molecular rates with inflated values obtained using recent calibrations. As recent demographic calibrations are virtually non-existent in most species, older phylogenetic calibration points (>1 Ma) are commonly used, which overestimate demographic parameters. To obtain more reliable rates of molecular evolution for population studies, I propose the calibration of demographic transition (CDT) method, which uses the timing of climatic changes over the late glacial warming period to calibrate expansions in various species. Simulation approaches and empirical data sets from a diversity of species (from mollusk to humans) confirm that, when compared with other genealogy-based calibration methods, the CDT provides a robust and broadly applicable clock for population genetics. The resulting CDT rates of molecular evolution also confirm rate heterogeneity over time and among taxa. Comparisons of expansion dates with ecological evidence confirm the inaccuracy of phylogenetically derived divergence rates when dating population-level events. The CDT method opens opportunities for addressing issues such as demographic responses to past climate change and the origin of rate heterogeneity related to taxa, genes, time, and genetic information content. PMID:26683588

  11. Genetic and demographic implications of the Bantu expansion: insights from human paternal lineages.

    PubMed

    Berniell-Lee, Gemma; Calafell, Francesc; Bosch, Elena; Heyer, Evelyne; Sica, Lucas; Mouguiama-Daouda, Patrick; van der Veen, Lolke; Hombert, Jean-Marie; Quintana-Murci, Lluis; Comas, David

    2009-07-01

    The expansion of Bantu languages, which started around 5,000 years before present in west/central Africa and spread all throughout sub-Saharan Africa, may represent one of the major and most rapid demographic movements in the history of the human species. Although the genetic footprints of this expansion have been unmasked through the analyses of the maternally inherited mitochondrial DNA lineages, information on the genetic impact of this massive movement and on the genetic composition of pre-Bantu populations is still scarce. Here, we analyze an extensive collection of Y-chromosome markers--41 single nucleotide polymorphisms and 18 short tandem repeats--in 883 individuals from 22 Bantu-speaking agriculturalist populations and 3 Pygmy hunter-gatherer populations from Gabon and Cameroon. Our data reveal a recent origin for most paternal lineages in west Central African populations most likely resulting from the expansion of Bantu-speaking farmers that erased the more ancient Y-chromosome diversity found in this area. However, some traces of ancient paternal lineages are observed in these populations, mainly among hunter-gatherers. These results are at odds with those obtained from mtDNA analyses, where high frequencies of ancient maternal lineages are observed, and substantial maternal gene flow from hunter-gatherers to Bantu farmers has been suggested. These differences are most likely explained by sociocultural factors such as patrilocality. We also find the intriguing presence of paternal lineages belonging to Eurasian haplogroup R1b1*, which might represent footprints of demographic expansions in central Africa not directly related to the Bantu expansion. PMID:19369595

  12. Postglacial range shift and demographic expansion of the marine intertidal snail Batillaria attramentaria

    PubMed Central

    Ho, Phuong-Thao; Kwan, Ye-Seul; Kim, Boa; Won, Yong-Jin

    2015-01-01

    To address the impacts of past climate changes, particularly since the last glacial period, on the history of the distribution and demography of marine species, we investigated the evolutionary and demographic responses of the intertidal batillariid gastropod, Batillaria attramentaria, to these changes, using the snail as a model species in the northwest Pacific. We applied phylogeographic and divergence population genetic approaches to mitochondrial COI sequences from B. attramentaria. To cover much of its distributional range, 197 individuals collected throughout Korea and 507 publically available sequences (mostly from Japan) were used. Finally, a Bayesian skyline plot (BSP) method was applied to reconstruct the demographic history of this species. We found four differentiated geographic groups around Korea, confirming the presence of two distinct, geographically subdivided haplogroups on the Japanese coastlines along the bifurcated routes of the warm Tsushima and Kuroshio Currents. These two haplogroups were estimated to have begun to split approximately 400,000 years ago. Population divergence analysis supported the hypothesis that the Yellow Sea was populated by a northward range expansion of a small fraction of founders that split from a southern ancestral population since the last glacial maximum (LGM: 26,000–19,000 years ago), when the southern area became re-submerged. BSP analyses on six geographically and genetically defined groups in Korea and Japan consistently demonstrated that each group has exponentially increased approximately since the LGM. This study resolved the phylogeography of B. attramentaria as a series of events connected over space and time; while paleoceanographic conditions determining the connectivity of neighboring seas in East Asia are responsible for the vicariance of this species, the postglacial sea-level rise and warming temperatures have played a crucial role in rapid range shifts and broad demographic expansions of its

  13. Demographic expansions in South America: enlightening a complex scenario with genetic and linguistic data.

    PubMed

    Ramallo, Virginia; Bisso-Machado, Rafael; Bravi, Claudio; Coble, Michael D; Salzano, Francisco M; Hünemeier, Tábita; Bortolini, Maria Cátira

    2013-03-01

    Native Americans are characterized by specific and unique patterns of genetic and cultural/linguistic diversities, and this information has been used to understand patterns of geographic dispersion, and the relationship between these peoples. Particularly interesting are the Tupi and Je speaker dispersions. At present, a large number of individuals speak languages of these two stocks; for instance, Tupi-Guarani is one of the official languages in Paraguay, Bolivia, and the Mercosul economic block. Although the Tupi expansion can be compared in importance to the Bantu migration in Africa, little is known about this event relative to others. Equal and even deeper gaps exist concerning the Je-speakers' expansion. This study aims to elucidate some aspects of these successful expansions. To meet this purpose, we analyzed Native American mtDNA complete control region from nine different populations and included HVS-I sequences available in the literature, resulting in a total of 1,176 samples investigated. Evolutionary relationships were explored through median-joining networks and genetic/geographic/linguistic correlations with Mantel tests and spatial autocorrelation analyses. Both Tupi and Je showed general traces of ancient or more recent fission-fusion processes, but a very different pattern of demographic expansion. Tupi populations displayed a classical isolation-by-distance pattern, while Je groups presented an intricate and nonlinear mode of dispersion. We suggest that the collective memory and other cultural processes could be important factors influencing the fission-fusion events, which likely contributed to the genetic structure, evolution, and dispersion of Native American populations. PMID:23341256

  14. Quaternary range and demographic expansion of Liolaemus darwinii (Squamata: Liolaemidae) in the Monte Desert of Central Argentina using Bayesian phylogeography and ecological niche modelling.

    PubMed

    Camargo, Arley; Werneck, Fernanda P; Morando, Mariana; Sites, Jack W; Avila, Luciano J

    2013-08-01

    Until recently, most phylogeographic approaches have been unable to distinguish between demographic and range expansion processes, making it difficult to test for the possibility of range expansion without population growth and vice versa. In this study, we applied a Bayesian phylogeographic approach to reconstruct both demographic and range expansion in the lizard Liolaemus darwinii of the Monte Desert in Central Argentina, during the Late Quaternary. Based on analysis of 14 anonymous nuclear loci and the cytochrome b mitochondrial DNA gene, we detected signals of demographic expansion starting at ~55 ka based on Bayesian Skyline and Skyride Plots. In contrast, Bayesian relaxed models of spatial diffusion suggested that range expansion occurred only between ~95 and 55 ka, and more recently, diffusion rates were very low during demographic expansion. The possibility of population growth without substantial range expansion could account for the shared patterns of demographic expansion during the Last Glacial Maxima (OIS 2 and 4) in fish, small mammals and other lizards of the Monte Desert. We found substantial variation in diffusion rates over time, and very high rates during the range expansion phase, consistent with a rapidly advancing expansion front towards the southeast shown by palaeo-distribution models. Furthermore, the estimated diffusion rates are congruent with observed dispersal rates of lizards in field conditions and therefore provide additional confidence to the temporal scale of inferred phylogeographic patterns. Our study highlights how the integration of phylogeography with palaeo-distribution models can shed light on both demographic and range expansion processes and their potential causes. PMID:23786355

  15. Phylogeography and demographic history of Lacerta lepida in the Iberian Peninsula: multiple refugia, range expansions and secondary contact zones

    PubMed Central

    2011-01-01

    Background The Iberian Peninsula is recognized as an important refugial area for species survival and diversification during the climatic cycles of the Quaternary. Recent phylogeographic studies have revealed Iberia as a complex of multiple refugia. However, most of these studies have focused either on species with narrow distributions within the region or species groups that, although widely distributed, generally have a genetic structure that relates to pre-Quaternary cladogenetic events. In this study we undertake a detailed phylogeographic analysis of the lizard species, Lacerta lepida, whose distribution encompasses the entire Iberian Peninsula. We attempt to identify refugial areas, recolonization routes, zones of secondary contact and date demographic events within this species. Results Results support the existence of 6 evolutionary lineages (phylogroups) with a strong association between genetic variation and geography, suggesting a history of allopatric divergence in different refugia. Diversification within phylogroups is concordant with the onset of the Pleistocene climatic oscillations. The southern regions of several phylogroups show a high incidence of ancestral alleles in contrast with high incidence of recently derived alleles in northern regions. All phylogroups show signs of recent demographic and spatial expansions. We have further identified several zones of secondary contact, with divergent mitochondrial haplotypes occurring in narrow zones of sympatry. Conclusions The concordant patterns of spatial and demographic expansions detected within phylogroups, together with the high incidence of ancestral haplotypes in southern regions of several phylogroups, suggests a pattern of contraction of populations into southern refugia during adverse climatic conditions from which subsequent northern expansions occurred. This study supports the emergent pattern of multiple refugia within Iberia but adds to it by identifying a pattern of refugia coincident

  16. Molecular Evidence of Demographic Expansion of the Chagas Disease Vector Triatoma dimidiata (Hemiptera, Reduviidae, Triatominae) in Colombia

    PubMed Central

    Gómez-Palacio, Andrés; Triana, Omar

    2014-01-01

    Background Triatoma dimidiata is one of the most significant vectors of Chagas disease in Central America and Colombia, and, as in most species, its pattern of genetic variation within and among populations is strongly affected by its phylogeographic history. A putative origin from Central America has been proposed for Colombian populations, and high genetic differentiation among three biographically different population groups has recently been evidenced. Analyses based on putatively neutral markers provide data from which past events, such as population expansions and colonization, can be inferred. We analyzed the genealogies of the nicotinamide adenine dinucleotide dehydrogenase 4 (ND4) and the cytochrome oxidase subunit 1-mitochondrial genes, as well as partial nuclear ITS-2 DNA sequences obtained across most of the eco-geographical range in Colombia, to assess the population structure and demographic factors that may explain the geographical distribution of T. dimidiata in this country. Results The population structure results support a significant association between genetic divergence and the eco-geographical location of population groups, suggesting that clear signals of demographic expansion can explain the geographical distribution of haplotypes of population groups. Additionally, empirical date estimation of the event suggests that the population's expansion can be placed after the emergence of the Panama Isthmus, and that it was possibly followed by a population fragmentation process, perhaps resulting from local adaptation accomplished by orographic factors such as geographical isolation. Conclusion Inferences about the historical population processes in Colombian T. dimidiata populations are generally in accordance with population expansions that may have been accomplished by two important biotic and orographic events such as the Great American Interchange and the uplift of the eastern range of the Andes mountains in central Colombia. PMID:24625572

  17. Genetic Signals of Demographic Expansion in Downy Woodpecker (Picoides pubescens) after the Last North American Glacial Maximum

    PubMed Central

    Pulgarín-R, Paulo C.; Burg, Theresa M.

    2012-01-01

    The glacial cycles of the Pleistocene have been recognized as important, large-scale historical processes that strongly influenced the demographic patterns and genetic structure of many species. Here we present evidence of a postglacial expansion for the Downy Woodpecker (Picoides pubescens), a common member of the forest bird communities in North America with a continental distribution. DNA sequences from the mitochondrial tRNA-Lys, and ATPase 6 and 8 genes, and microsatellite data from seven variable loci were combined with a species distribution model (SDM) to infer possible historical scenarios for this species after the last glacial maximum. Analyses of Downy Woodpeckers from 23 geographic areas suggested little differentiation, shallow genealogical relationships, and limited population structure across the species’ range. Microsatellites, which have higher resolution and are able to detect recent differences, revealed two geographic groups where populations along the eastern edge of the Rocky Mountains (Montana, Utah, Colorado, and southern Alberta) were genetically isolated from the rest of the sampled populations. Mitochondrial DNA, an important marker to detect historical patterns, recovered only one group. However, populations in Idaho and southeast BC contained high haplotype diversity and, in general were characterized by the absence of the most common mtDNA haplotype. The SDM suggested several areas in the southern US as containing suitable Downy Woodpecker habitat during the LGM. The lack of considerable geographic structure and the starburst haplotype network, combined with several population genetic tests, suggest a scenario of demographic expansion during the last part of Pleistocene and early Holocene. PMID:22792306

  18. Population panmixia and the Pleistocene demographic expansion of spotty belly greenling Hexagrammos agrammus in the East Sea and Northwest Pacific

    NASA Astrophysics Data System (ADS)

    Habib, Kazi Ahsan; Jeong, Dageum; Myoung, Jung-Goo; Lee, Youn-Ho

    2015-06-01

    The population genetic structure and historical demography of spotty belly greenling, Hexagrammos agrammus, which has limited distribution in the Northwest Pacific, was assessed with partial sequences of the mitochondrial DNA (mtDNA) cytochrome b and the control region (D-loop). A total of 103 individuals were collected from four sites located at the Korea Strait (Southern coast of Korea) and the East coast of Korea and two places in the Pacific coast of Japan. For all the populations, nucleotide diversities were low (0.006-0.009) while the haplotype diversities were as high as 0.92 to 0.97, indicating that the fish has undergone a recent population expansion after experiencing bottleneck. Star-shaped patterns of haplotype networks as well as the significant negative values of Tajima's D and Fu's F S corroborate the recent population expansion. Mismatch distribution analysis reveals that the demographic expansion of the species started during the 2nd half of the Middle Pleistocene Series approximately 141,000-406,000 years ago. Hierarchical analysis of molecular variance (AMOVA), the pairwise population statistics ( F ST), and the exact test of haplotype differentiation demonstrate no significant genetic differentiation among populations investigated, suggesting that spotty belly greenling is panmictic in the East Sea and the Pacific coast of Japan.

  19. Explosive demographic expansion by dreissenid bivalves as a possible result of astronomical forcing

    NASA Astrophysics Data System (ADS)

    Harzhauser, M.; Mandic, O.; Kern, A. K.; Piller, W. E.; Neubauer, T. A.; Albrecht, C.; Wilke, T.

    2013-12-01

    Human induced range expansions of invasive dreissenid bivalves are of great concern. However, the underlying biological processes are only poorly understood, partly due to the lack of information on natural expansion events. Here we use the extinct bivalve species Sinucongeria primiformis as a model organism for testing natural (i.e. pre-Anthropocene) blooms of dreissenid species in a lacustrine system of Lake Pannon during the Tortonian (~ 10.5 Myr; late Miocene). A total of 600 samples from a consecutive core were evaluated for the relative abundance of this pavement-forming mollusc, which cover about eight millennia of late Miocene time with a decadal resolution. Our data indicate that the settlement by bivalves in the offshore environment was limited mainly by bottom water oxygenation, which follows predictable and repetitive patterns through time. These population fluctuations might be related to solar cycles: successful dreissenid settlement is recurring in a frequency known as the lower and upper Gleissberg cycles with 50-80 and 90-120 yr periods. These cycles appear to control regional wind patterns, which are directly linked to water mixing of the lake. This is modulated by the even more prominent 500 yr cycle, which seems to be the most important pacemaker for Lake Pannon hydrology.

  20. Explosive demographic expansion by dreissenid bivalves as a possible result of astronomical forcing

    NASA Astrophysics Data System (ADS)

    Harzhauser, M.; Mandic, O.; Kern, A. K.; Piller, W. E.; Neubauer, T. A.; Albrecht, C.; Wilke, T.

    2013-07-01

    Human induced range expansions of invasive dreissenid bivalves are of great concern. However, the underlying biological processes are only poorly understood, partly due to the lack of information on natural expansion events. Here we use the extinct bivalve species Sinucongeria primiformis as a model organism for testing natural (i.e. non-Anthropocene) blooms of dreissenid species in a lacustrine system of Lake Pannon during the Tortonian (~10.5 Myr; Late Miocene). 600 samples from a consecutive core were evaluated for the relative abundance of this pavement-forming mollusc, which cover about 8 millennia of Late Miocene time with a decadal resolution. Our data indicate that the settlement by bivalves in the offshore environment was limited mainly by bottom water oxygenation, which follows predictable and repetitive patterns through time. These population fluctuations might be related to solar cycles: successful dreissenid settlement is re-occurring in a frequency known as the lower and upper Gleissberg cycles with a 50-80 and 90-120 yr period. These cycles appear to control regional wind patterns, which are directly linked to water mixing of the lake. This is modulated by the even more prominent 500 yr cycle, which seems to be the most important pacemaker for Lake Pannon hydrology.

  1. Range-wide patterns of greater sage-grouse persistence

    USGS Publications Warehouse

    Aldridge, C.L.; Nielsen, S.E.; Beyer, H.L.; Boyce, M.S.; Connelly, J.W.; Knick, S.T.; Schroeder, M.A.

    2008-01-01

    population growth and peripherality of populations. However, future range loss may relate less to historical mechanisms and more to recent changes in land use and habitat condition, including energy developments and invasions by non-native species such as cheatgrass (Bromus tectorum) and West Nile virus. In conjunction with local measures of population performance, landscape-scale predictions of future range loss may be useful for prioritizing management and protection. Our results suggest that initial conservation efforts should focus on maintaining large expanses of sagebrush habitat, enhancing quality of existing habitats, and increasing habitat connectivity.

  2. Genetic Signatures of Demographic Changes in an Avian Top Predator during the Last Century: Bottlenecks and Expansions of the Eurasian Eagle Owl in the Iberian Peninsula

    PubMed Central

    Graciá, Eva; Ortego, Joaquín; Godoy, José Antonio; Pérez-García, Juan Manuel; Blanco, Guillermo; del Mar Delgado, María; Penteriani, Vincenzo; Almodóvar, Irene; Botella, Francisco; Sánchez-Zapata, José Antonio

    2015-01-01

    The study of the demographic history of species can help to understand the negative impact of recent population declines in organisms of conservation concern. Here, we use neutral molecular markers to explore the genetic consequences of the recent population decline and posterior recovery of the Eurasian eagle owl (Bubo bubo) in the Iberian Peninsula. During the last century, the species was the object of extermination programs, suffering direct persecution by hunters until the 70’s. Moreover, during the last decades the eagle owl was severely impacted by increased mortality due to electrocution and the decline of its main prey species, the European rabbit (Oryctolagus cuniculus). In recent times, the decrease of direct persecution and the implementation of some conservation schemes have allowed the species’ demographic recovery. Yet, it remains unknown to which extent the past population decline and the later expansion have influenced the current species’ pattern of genetic diversity. We used eight microsatellite markers to genotype 235 eagle owls from ten Spanish subpopulations and analyse the presence of genetic signatures attributable to the recent population fluctuations experienced by the species. We found moderate levels of differentiation among the studied subpopulations and Bayesian analyses revealed the existence of three genetic clusters that grouped subpopulations from central, south-western and south-eastern Spain. The observed genetic structure could have resulted from recent human-induced population fragmentation, a patchy distribution of prey populations and/or the philopatric behaviour and habitat selection of the species. We detected an old population bottleneck, which occurred approximately 10,000 years ago, and significant signatures of recent demographic expansions. However, we did not find genetic signatures for a recent bottleneck, which may indicate that population declines were not severe enough to leave detectable signals on the

  3. Demographic Inference Using Spectral Methods on SNP Data, with an Analysis of the Human Out-of-Africa Expansion

    PubMed Central

    Lukić, Sergio; Hey, Jody

    2012-01-01

    We present an implementation of a recently introduced method for estimating the allele-frequency spectrum under the diffusion approximation. For single-nucleotide polymorphism (SNP) frequency data from multiple populations, the method computes numerical solutions to the allele-frequency spectrum (AFS) under a complex model that includes population splitting events, migration, population expansion, and admixture. The solution to the diffusion partial differential equation (PDE) that mimics the evolutionary process is found by means of truncated polynomial expansions. In the absence of gene flow, our computation of frequency spectra yields exact results. The results are compared to those that use a finite-difference method and to forward diffusion simulations. In general, all the methods yield comparable results, although the polynomial-based approach is the most accurate in the weak-migration limit. Also, the economical use of memory attained by the polynomial expansions makes the study of models with four populations possible for the first time. The method was applied to a four-population model of the human expansion out of Africa and the peopling of the Americas, using the Environmental Genome Project (EGP) SNP database. Although our confidence intervals largely overlapped previous analyses of these data, some were significantly different. In particular, estimates of migration among African, European, and Asian populations were considerably lower than those in a previous study and the estimated time of migration out of Africa was earlier. The estimated time of founding of a human population outside of Africa was 52,000 years (95% confidence interval: 36,000–80,800 years). PMID:22865734

  4. Phylogeography and Demographic History of Chinese Black-Spotted Frog Populations (Pelophylax nigromaculata): Evidence for Independent Refugia Expansion and Secondary Contact

    PubMed Central

    2008-01-01

    Background Pleistocene glaciations had considerable impact on phylogeographic patterns within and among closely related species of many vertebrates. Compared to Europe and North America, research on the phylogeography of vertebrates in East Asia, particularly in China, remains limited. The black-spotted frog (Pelophylax nigromaculata) is a widespread species in East Asia. The wide distribution of this species in China makes it an ideal model for the study of palaeoclimatic effects on vertebrates in East Asia. Our previous studies of P. nigromaculata revealed significant subdivisions between the northeast China populations and populations in other regions of the mainland. In the present study, we aim to see whether the deepest splits among lineages and perhaps subsequent genealogical divisions are temporally consistent with a Pleistocene origin and whether clade geographic distributions, with insight into expansion patterns, are similarly spatially consistent with this model. Results Using 1143 nucleotides of the mitochondrial cytochrome b gene from 262 individuals sampled from 28 localities, two main clades (clade A and clade B) differing by c. 7.72% sequence divergence were defined from parsimony analyses. The corresponding timing of lineage divergence, 0.92 Mya, indicates a most likely Pleistocene split. The A clade is further subdivided into two sub-clades, A1 and A2 with 1.22% sequence divergence. Nested clade phylogeographical and population demographic analyses suggested that the current distribution of this frog species was the result of range expansion from two independent refugia during the last interglacial period. We discovered a population within which haplotype lineages A and B of P. nigromaculata coexist in the Dongliao area of China by nucleotide sequences, PCR-RFLP and ISSR (inter simple sequence repeat) patterns. The ISSR result in particular supported divergence between the mitochondrial clades A and B and implied introgressive gene flow between

  5. A range-wide synthesis and timeline for phylogeographic events in the red fox (Vulpes vulpes)

    PubMed Central

    2013-01-01

    Background Many boreo-temperate mammals have a Pleistocene fossil record throughout Eurasia and North America, but only few have a contemporary distribution that spans this large area. Examples of Holarctic-distributed carnivores are the brown bear, grey wolf, and red fox, all three ecological generalists with large dispersal capacity and a high adaptive flexibility. While the two former have been examined extensively across their ranges, no phylogeographic study of the red fox has been conducted across its entire Holarctic range. Moreover, no study included samples from central Asia, leaving a large sampling gap in the middle of the Eurasian landmass. Results Here we provide the first mitochondrial DNA sequence data of red foxes from central Asia (Siberia), and new sequences from several European populations. In a range-wide synthesis of 729 red fox mitochondrial control region sequences, including 677 previously published and 52 newly obtained sequences, this manuscript describes the pattern and timing of major phylogeographic events in red foxes, using a Bayesian coalescence approach with multiple fossil tip and root calibration points. In a 335 bp alignment we found in total 175 unique haplotypes. All newly sequenced individuals belonged to the previously described Holarctic lineage. Our analyses confirmed the presence of three Nearctic- and two Japan-restricted lineages that were formed since the Mid/Late Pleistocene. Conclusions The phylogeographic history of red foxes is highly similar to that previously described for grey wolves and brown bears, indicating that climatic fluctuations and habitat changes since the Pleistocene had similar effects on these highly mobile generalist species. All three species originally diversified in Eurasia and later colonized North America and Japan. North American lineages persisted through the last glacial maximum south of the ice sheets, meeting more recent colonizers from Beringia during postglacial expansion into the

  6. Forecasting deforestation and carbon emissions in tropical developing countries facing demographic expansion: a case study in Madagascar.

    PubMed

    Vieilledent, Ghislain; Grinand, Clovis; Vaudry, Romuald

    2013-06-01

    Anthropogenic deforestation in tropical countries is responsible for a significant part of global carbon dioxide emissions in the atmosphere. To plan efficient climate change mitigation programs (such as REDD+, Reducing Emissions from Deforestation and forest Degradation), reliable forecasts of deforestation and carbon dioxide emissions are necessary. Although population density has been recognized as a key factor in tropical deforestation, current methods of prediction do not allow the population explosion that is occurring in many tropical developing countries to be taken into account. Here, we propose an innovative approach using novel computational and statistical tools, including R/GRASS scripts and the new phcfM R package, to model the intensity and location of deforestation including the effect of population density. We used the model to forecast anthropogenic deforestation and carbon dioxide emissions in five large study areas in the humid and spiny-dry forests of Madagascar. Using our approach, we were able to demonstrate that the current rapid population growth in Madagascar (+3.39% per year) will significantly increase the intensity of deforestation by 2030 (up to +1.17% per year in densely populated areas). We estimated the carbon dioxide emissions associated with the loss of aboveground biomass to be of 2.24 and 0.26 tons per hectare and per year in the humid and spiny-dry forest, respectively. Our models showed better predictive ability than previous deforestation models (the figure of merit ranged from 10 to 23). We recommend this approach to reduce the uncertainty associated with deforestation forecasts. We also underline the risk of an increase in the speed of deforestation in the short term in tropical developing countries undergoing rapid population expansion. PMID:23789079

  7. New mitochondrial and nuclear evidences support recent demographic expansion and an atypical phylogeographic pattern in the spittlebug Philaenus spumarius (Hemiptera, Aphrophoridae).

    PubMed

    Rodrigues, Ana S B; Silva, Sara E; Marabuto, Eduardo; Silva, Diogo N; Wilson, Mike R; Thompson, Vinton; Yurtsever, Selçuk; Halkka, Antti; Borges, Paulo A V; Quartau, José A; Paulo, Octávio S; Seabra, Sofia G

    2014-01-01

    Philaenus spumarius is a widespread insect species in the Holarctic region. Here, by focusing on the mtDNA gene COI but also using the COII and Cyt b genes and the nuclear gene EF-1α, we tried to explain how and when its current biogeographic pattern evolved by providing time estimates of the main demographic and evolutionary events and investigating its colonization patterns in and out of Eurasia. Evidence of recent divergence and expansion events at less than 0.5 Ma ago indicate that climate fluctuations in the Mid-Late Pleistocene were important in shaping the current phylogeographic pattern of the species. Data support a first split and differentiation of P. spumarius into two main mitochondrial lineages: the "western", in the Mediterranean region and the "eastern", in Anatolia/Caucasus. It also supports a following differentiation of the "western" lineage into two sub-lineages: the "western-Mediterranean", in Iberia and the "eastern-Mediterranean" in the Balkans. The recent pattern seems to result from postglacial range expansion from Iberia and Caucasus/Anatolia, thus not following one of the four common paradigms. Unexpected patterns of recent gene-flow events between Mediterranean peninsulas, a close relationship between Iberia and North Africa, as well as high levels of genetic diversity being maintained in northern Europe were found. The mitochondrial pattern does not exactly match to the nuclear pattern suggesting that the current biogeographic pattern of P. spumarius may be the result of both secondary admixture and incomplete lineage sorting. The hypothesis of recent colonization of North America from both western and northern Europe is corroborated by our data and probably resulted from accidental human translocations. A probable British origin for the populations of the Azores and New Zealand was revealed, however, for the Azores the distribution of populations in high altitude native forests is somewhat puzzling and may imply a natural colonization

  8. New Mitochondrial and Nuclear Evidences Support Recent Demographic Expansion and an Atypical Phylogeographic Pattern in the Spittlebug Philaenus spumarius (Hemiptera, Aphrophoridae)

    PubMed Central

    Rodrigues, Ana S. B.; Silva, Sara E.; Marabuto, Eduardo; Silva, Diogo N.; Wilson, Mike R.; Thompson, Vinton; Yurtsever, Selçuk; Halkka, Antti; Borges, Paulo A. V.; Quartau, José A.; Paulo, Octávio S.; Seabra, Sofia G.

    2014-01-01

    Philaenus spumarius is a widespread insect species in the Holarctic region. Here, by focusing on the mtDNA gene COI but also using the COII and Cyt b genes and the nuclear gene EF-1α, we tried to explain how and when its current biogeographic pattern evolved by providing time estimates of the main demographic and evolutionary events and investigating its colonization patterns in and out of Eurasia. Evidence of recent divergence and expansion events at less than 0.5 Ma ago indicate that climate fluctuations in the Mid-Late Pleistocene were important in shaping the current phylogeographic pattern of the species. Data support a first split and differentiation of P. spumarius into two main mitochondrial lineages: the “western”, in the Mediterranean region and the “eastern”, in Anatolia/Caucasus. It also supports a following differentiation of the “western” lineage into two sub-lineages: the “western-Mediterranean”, in Iberia and the “eastern-Mediterranean” in the Balkans. The recent pattern seems to result from postglacial range expansion from Iberia and Caucasus/Anatolia, thus not following one of the four common paradigms. Unexpected patterns of recent gene-flow events between Mediterranean peninsulas, a close relationship between Iberia and North Africa, as well as high levels of genetic diversity being maintained in northern Europe were found. The mitochondrial pattern does not exactly match to the nuclear pattern suggesting that the current biogeographic pattern of P. spumarius may be the result of both secondary admixture and incomplete lineage sorting. The hypothesis of recent colonization of North America from both western and northern Europe is corroborated by our data and probably resulted from accidental human translocations. A probable British origin for the populations of the Azores and New Zealand was revealed, however, for the Azores the distribution of populations in high altitude native forests is somewhat puzzling and may imply a

  9. Simulating range-wide population and breeding habitat dynamics for an endangered woodland warbler in the face of uncertainty

    USGS Publications Warehouse

    Adam Duarte; Hatfield, Jeffrey; Todd M. Swannack; Michael R. J. Forstner; M. Clay Green; Floyd W. Weckerly

    2015-01-01

    Population viability analyses provide a quantitative approach that seeks to predict the possible future status of a species of interest under different scenarios and, therefore, can be important components of large-scale species’ conservation programs. We created a model and simulated range-wide population and breeding habitat dynamics for an endangered woodland warbler, the golden-cheeked warbler (Setophaga chrysoparia). Habitat-transition probabilities were estimated across the warbler's breeding range by combining National Land Cover Database imagery with multistate modeling. Using these estimates, along with recently published demographic estimates, we examined if the species can remain viable into the future given the current conditions. Lastly, we evaluated if protecting a greater amount of habitat would increase the number of warblers that can be supported in the future by systematically increasing the amount of protected habitat and comparing the estimated terminal carrying capacity at the end of 50 years of simulated habitat change. The estimated habitat-transition probabilities supported the hypothesis that habitat transitions are unidirectional, whereby habitat is more likely to diminish than regenerate. The model results indicated population viability could be achieved under current conditions, depending on dispersal. However, there is considerable uncertainty associated with the population projections due to parametric uncertainty. Model results suggested that increasing the amount of protected lands would have a substantial impact on terminal carrying capacities at the end of a 50-year simulation. Notably, this study identifies the need for collecting the data required to estimate demographic parameters in relation to changes in habitat metrics and population density in multiple regions, and highlights the importance of establishing a common definition of what constitutes protected habitat, what management goals are suitable within those protected

  10. Range-wide conservation assessment of Greater Sage-Grouse and sagebrush habitats

    USGS Publications Warehouse

    U.S. Geological Survey

    2003-01-01

    Declining numbers of Greater Sage-grouse (Centrocercus urophasianus) over the past three decades across most of their range accompanied by increasing habitat degradation and loss represent major conservation and management challenges. We are conducting a range-wide Conservation Assessment of Greater Sage-grouse and sagebrush habitats. This assessment is an interagency effort sponsored by the Western Association of Fish and Wildlife Agencies to determine the status of Greater Sage-grouse and their habitats, and identify potential threats to their long-term survival. Agencies, private organizations, and landowners have an urgent need for this assessment because of conflicting views concerning causes of declines and the appropriate management actions.

  11. Spatiotemporal variation in range-wide Golden-cheeked Warbler habitat

    USGS Publications Warehouse

    Duarte, Adam; Jensen, Jennifer; Hatfield, Jeffrey S.; Weckerly, Floyd

    2013-01-01

    Habitat availability ultimately limits the distribution and abundance of wildlife species. Consequently, it is paramount to identify where wildlife habitat is and understand how it changes over time in order to implement large scale wildlife conservation plans. Yet, no work has quantified the degree of change in range-wide breeding habitat for the golden-cheeked warbler (Setophaga chrysoparia), despite the species being listed as endangered by the U.S. federal government. Thus, using available geographic information system (GIS) data and Landsat satellite imagery we quantified range-wide warbler breeding habitat change from 1999-2001 to 2010-2011. We detected a 29% reduction in total warbler breeding habitat and found that warbler breeding habitat was removed and became more fragmented at uneven rates across the warbler’s breeding range during this time period. This information will assist researchers and managers in prioritizing breeding habitat conservation efforts for the species and provide a foundation for more realistic carrying capacity scenarios when modeling golden-cheeked warbler populations over time. Additionally, this study highlights the need for future work centered on quantifying golden-cheeked warbler movement rates and distances in order to assess the degree of connectivity between increasingly fragmented habitat patches.

  12. Range-wide assessment of livestock grazing across the sagebrush biome

    USGS Publications Warehouse

    Veblen, Kari E.; Pyke, David A.; Aldridge, Cameron L.; Casazza, Michael L.; Assal, Timothy J.; Farinha, Melissa A.

    2011-01-01

    Domestic livestock grazing occurs in virtually all sagebrush habitats and is a prominent disturbance factor. By affecting habitat condition and trend, grazing influences the resources required by, and thus, the distribution and abundance of sagebrush-obligate wildlife species (for example, sage-grouse Centrocercus spp.). Yet, the risks that livestock grazing may pose to these species and their habitats are not always clear. Although livestock grazing intensity and associated habitat condition may be known in many places at the local level, we have not yet been able to answer questions about use, condition, and trend at the landscape scale or at the range-wide scale for wildlife species. A great deal of information about grazing use, management regimes, and ecological condition exists at the local level (for individual livestock management units) under the oversight of organizations such as the Bureau of Land Management (BLM). However, the extent, quality, and types of existing data are unknown, which hinders the compilation, mapping, or analysis of these data. Once compiled, these data may be helpful for drawing conclusions about rangeland status, and we may be able to identify relationships between those data and wildlife habitat at the landscape scale. The overall objective of our study was to perform a range-wide assessment of livestock grazing effects (and the relevant supporting data) in sagebrush ecosystems managed by the BLM. Our assessments and analyses focused primarily on local-level management and data collected at the scale of BLM grazing allotments (that is, individual livestock management units). Specific objectives included the following: 1. Identify and refine existing range-wide datasets to be used for analyses of livestock grazing effects on sagebrush ecosystems. 2. Assess the extent, quality, and types of livestock grazing-related natural resource data collected by BLM range-wide (i.e., across allotments, districts and regions). 3. Compile and

  13. Recommended methods for range-wide monitoring of prairie dogs in the United States

    USGS Publications Warehouse

    McDonald, Lyman L.; Stanley, Thomas R.; Otis, David L.; Biggins, Dean E.; Stevens, Patricia D.; Koprowski, John L.; Ballard, Warren

    2011-01-01

    One of the greatest challenges for conserving grassland, prairie scrub, and shrub-steppe ecosystems is maintaining prairie dog populations across the landscape. Of the four species of prairie dogs found in the United States, the Utah prairie dog (Cynomys parvidens) is listed under the Endangered Species Act (ESA) as threatened, the Gunnison's prairie dog (C. gunnisoni) is a candidate for listing in a portion of its range, and the black-tailed prairie dog (C. ludovicianus) and white-tailed prairie dog (C. leucurus) have each been petitioned for listing at least once in recent history. Although the U.S. Fish and Wildlife Service (USFWS) determined listing is not warranted for either the black-tailed prairie dog or white-tailed prairie dog, the petitions and associated reviews demonstrated the need for the States to monitor and manage for self-sustaining populations. In response to these findings, a multi-State conservation effort was initiated for the nonlisted species which included the following proposed actions: (1) completing an assessment of each prairie dog species in each State, (2) developing a range-wide monitoring protocol for each species using a statistically valid sampling procedure that would allow comparable analyses across States, and (3) monitoring prairie dog status every 3-5 years depending upon the species. To date, each State has completed an assessment and currently is monitoring prairie dog status; however, for some species, the inconsistency in survey methodology has made it difficult to compare data year-to-year or State-to-State. At the Prairie Dog Conservation Team meeting held in November 2008, there was discussion regarding the use of different methods to survey prairie dogs. A recommendation from this meeting was to convene a panel in a workshop-type forum and have the panel review the different methods being used and provide recommendations for range-wide monitoring protocols for each species of prairie dog. Consequently, the Western

  14. Range-wide mtDNA phylogeography yields insights into the origins of Asian elephants.

    PubMed

    Vidya, T N C; Sukumar, Raman; Melnick, Don J

    2009-03-01

    Recent phylogeographic studies of the endangered Asian elephant (Elephas maximus) reveal two highly divergent mitochondrial DNA (mtDNA) lineages, an elucidation of which is central to understanding the species's evolution. Previous explanations for the divergent clades include introgression of mtDNA haplotypes between ancestral species, allopatric divergence of the clades between Sri Lanka or the Sunda region and the mainland, historical trade of elephants, and retention of divergent lineages due to large population sizes. However, these studies lacked data from India and Myanmar, which host approximately 70 per cent of all extant Asian elephants. In this paper, we analyse mtDNA sequence data from 534 Asian elephants across the species's range to explain the current distribution of the two divergent clades. Based on phylogenetic reconstructions, estimates of times of origin of clades, probable ancestral areas of origin inferred from dispersal-vicariance analyses and the available fossil record, we believe both clades originated from Elephas hysudricus. This probably occurred allopatrically in different glacial refugia, the alpha clade in the Myanmar region and the beta clade possibly in southern India-Sri Lanka, 1.6-2.1Myr ago. Results from nested clade and dispersal-vicariance analyses indicate a subsequent isolation and independent diversification of the beta clade in both Sri Lanka and the Sunda region, followed by northward expansion of the clade. We also find more recent population expansions in both clades based on mismatch distributions. We therefore suggest a contraction-expansion scenario during severe climatic oscillations of the Quaternary, with range expansions from different refugia during warmer interglacials leading to the varying geographical overlaps of the two mtDNA clades. We also demonstrate that trade in Asian elephants has not substantially altered the species's mtDNA population genetic structure. PMID:19019786

  15. Assessing the umbrella value of a range-wide conservation network for jaguars (Panthera onca).

    PubMed

    Thornton, Daniel; Zeller, Kathy; Rondinini, Carlo; Boitani, Luigi; Crooks, Kevin; Burdeh, Christopher; Rabinowitz, Alan; Quigley, Howard

    2016-06-01

    Umbrella species are employed as conservation short-cuts for the design of reserves or reserve networks. However, empirical data on the effectiveness of umbrellas is equivocal, which has prevented more widespread application of this conservation strategy. We perform a novel, large-scale evaluation of umbrella species by assessing the potential umbrella value of a jaguar (Panthera onca) conservation network (consisting of viable populations and corridors) that extends from Mexico to Argentina. Using species richness, habitat quality, and fragmentation indices of ~1500 co-occurring mammal species, we show that jaguar populations and corridors overlap a substantial amount and percentage of high-quality habitat for co-occurring mammals and that the jaguar network performs better than random networks in protecting high-quality, interior habitat. Significantly, the effectiveness of the jaguar network as an umbrella would not have been noticeable had we focused on species richness as our sole metric of umbrella utility. Substantial inter-order variability existed, indicating the need for complementary conservation strategies for certain groups of mammals. We offer several reasons for the positive result we document, including the large spatial scale of our analysis and our focus on multiple metrics of umbrella effectiveness. Taken together, our results demonstrate that a regional, single-species conservation strategy can serve as an effective umbrella for the larger community and should help conserve viable populations and connectivity for a suite of co-occurring mammals. Current and future range-wide planning exercises for other large predators may therefore have important umbrella benefits. PMID:27509752

  16. Data resources for range-wide assessment of livestock grazing across the sagebrush biome

    USGS Publications Warehouse

    Assal, T.J.; Veblen, K.E.; Farinha, M.A.; Aldridge, C.L.; Casazza, M.L.; Pyke, D.A.

    2012-01-01

    The data contained in this series were compiled, modified, and analyzed for the U.S. Geological Survey (USGS) report "Range-Wide Assessment of Livestock Grazing Across the Sagebrush Biome." This report can be accessed through the USGS Publications Warehouse (online linkage: http://pubs.usgs.gov/of/2011/1263/). The dataset contains spatial and tabular data related to Bureau of Land Management (BLM) Grazing Allotments. We reviewed the BLM national grazing allotment spatial dataset available from the GeoCommunicator National Integrated Land System (NILS) website in 2007 (http://www.geocommunicator.gov). We identified several limitations in those data and learned that some BLM State and/or field offices had updated their spatial data to rectify these limitations, but maintained the data outside of NILS. We contacted appropriate BLM offices (State or field, 25 in all) to obtain the most recent data, assessed the data, established a data development protocol, and compiled data into a topologically enforced dataset throughout the area of interest for this project (that is, the pre-settlement distribution of Greater Sage-Grouse in the Western United States). The final database includes three spatial datasets: Allotments (BLM Grazing Allotments), OUT_Polygons (nonallotment polygons used to ensure topology), and Duplicate_Polygon_Allotments. See Appendix 1 of the aforementioned report for complete methods. The tabular data presented here consists of information synthesized by the Land Health Standard (LHS) analysis (Appendix 2), and data obtained from the BLM Rangeland Administration System (http://www.blm.gov/ras/). In 2008, available LHS data for all allotments in all regions were compiled by BLM in response to a Freedom of Information Act (FOIA) request made by a private organization. The BLM provided us with a copy of these data. These data provided three major types of information that were of interest: (1) date(s) (if any) of the most recent LHS evaluation for each

  17. Demographic entrapment.

    PubMed

    King, M

    1993-04-01

    Demographic entrapment is a situation in which a population exceeds the carrying capacity of its own ecosystem and its 'connectedness' to other ecosystems. It can be looked upon as a disorder of the demographic transition which presents serious ethical problems in that there are occasions on which there is a conflict between the interests of the child and the community. Reasons are given for the aid agencies' recognizing the existence of entrapment, which presently they do not. Since there are at present considerable obstacles to their doing this, we must accept a period of 'legitimate double-think' meanwhile. PMID:8337744

  18. Southern montane populations did not contribute to the recolonization of West Siberian Plain by Siberian larch (Larix sibirica): a range-wide analysis of cytoplasmic markers.

    PubMed

    Semerikov, Vladimir L; Semerikova, Svetlana A; Polezhaeva, Maria A; Kosintsev, Pavel A; Lascoux, Martin

    2013-10-01

    While many species were confined to southern latitudes during the last glaciations, there has lately been mounting evidence that some of the most cold-tolerant species were actually able to survive close to the ice sheets. The contribution of these higher latitude outposts to the main recolonization thrust remains, however, untested. In the present study, we use the first range-wide survey of genetic diversity at cytoplasmic markers in Siberian larch (Larix sibirica; four mitochondrial (mt) DNA loci and five chloroplast (cp) DNA SSR loci) to (i) assess the relative contributions of southern and central areas to the current L. sibirica distribution range; and (ii) date the last major population expansion in both L. sibirica and adjacent Larix species. The geographic distribution of cpDNA variation was uninformative, but that of mitotypes clearly indicates that the southernmost populations, located in Mongolia and the Tien-Shan and Sayan Mountain ranges, had a very limited contribution to the current populations of the central and northern parts of the range. It also suggests that the contribution of the high latitude cryptic refugia was geographically limited and that most of the current West Siberian Plain larch populations likely originated in the foothills of the Sayan Mountains. Interestingly, the main population expansion detected through Approximate Bayesian Computation (ABC) in all four larch species investigated here pre-dates the LGM, with a mode in a range of 220,000-1,340,000 years BP. Hence, L. sibirica, like other major conifer species of the boreal forest, was strongly affected by climatic events pre-dating the Last Glacial Maximum. PMID:24033458

  19. Using Range-Wide Abundance Modeling to Identify Key Conservation Areas for the Micro-Endemic Bolson Tortoise (Gopherus flavomarginatus).

    PubMed

    Ureña-Aranda, Cinthya A; Rojas-Soto, Octavio; Martínez-Meyer, Enrique; Yáñez-Arenas, Carlos; Landgrave Ramírez, Rosario; Espinosa de los Monteros, Alejandro

    2015-01-01

    A widespread biogeographic pattern in nature is that population abundance is not uniform across the geographic range of species: most occurrence sites have relatively low numbers, whereas a few places contain orders of magnitude more individuals. The Bolson tortoise Gopherus flavomarginatus is endemic to a small region of the Chihuahuan Desert in Mexico, where habitat deterioration threatens this species with extinction. In this study we combined field burrows counts and the approach for modeling species abundance based on calculating the distance to the niche centroid to obtain range-wide abundance estimates. For the Bolson tortoise, we found a robust, negative relationship between observed burrows abundance and distance to the niche centroid, with a predictive capacity of 71%. Based on these results we identified four priority areas for the conservation of this microendemic and threatened tortoise. We conclude that this approach may be a useful approximation for identifying key areas for sampling and conservation efforts in elusive and rare species. PMID:26115482

  20. Using Range-Wide Abundance Modeling to Identify Key Conservation Areas for the Micro-Endemic Bolson Tortoise (Gopherus flavomarginatus)

    PubMed Central

    Ureña-Aranda, Cinthya A.; Rojas-Soto, Octavio; Martínez-Meyer, Enrique; Yáñez-Arenas, Carlos; Landgrave Ramírez, Rosario; Espinosa de los Monteros, Alejandro

    2015-01-01

    A widespread biogeographic pattern in nature is that population abundance is not uniform across the geographic range of species: most occurrence sites have relatively low numbers, whereas a few places contain orders of magnitude more individuals. The Bolson tortoise Gopherus flavomarginatus is endemic to a small region of the Chihuahuan Desert in Mexico, where habitat deterioration threatens this species with extinction. In this study we combined field burrows counts and the approach for modeling species abundance based on calculating the distance to the niche centroid to obtain range-wide abundance estimates. For the Bolson tortoise, we found a robust, negative relationship between observed burrows abundance and distance to the niche centroid, with a predictive capacity of 71%. Based on these results we identified four priority areas for the conservation of this microendemic and threatened tortoise. We conclude that this approach may be a useful approximation for identifying key areas for sampling and conservation efforts in elusive and rare species. PMID:26115482

  1. Conservation genetics of the alligator snapping turtle: cytonuclear evidence of range-wide bottleneck effects and unusually pronounced geographic structure

    USGS Publications Warehouse

    Echelle, A.A.; Hackler, J.C.; Lack, Justin B.; Ballard, S. R.; Roman, J.; Fox, S. F.; Leslie,, David M., Jr.; Van Den Bussche, Ronald A.

    2010-01-01

    A previous mtDNA study indicated that female-mediated gene flow was extremely rare among alligator snapping turtle populations in different drainages of the Gulf of Mexico. In this study, we used variation at seven microsatellite DNA loci to assess the possibility of male-mediated gene flow, we augmented the mtDNA survey with additional sampling of the large Mississippi River System, and we evaluated the hypothesis that the consistently low within-population mtDNA diversity reflects past population bottlenecks. The results show that dispersal between drainages of the Gulf of Mexico is rare (F STmsat  = 0.43, ΦSTmtDNA = 0.98). Past range-wide bottlenecks are indicated by several genetic signals, including low diversity for microsatellites (1.1–3.9 alleles/locus; H e = 0.06–0.53) and mtDNA (h = 0.00 for most drainages; π = 0.000–0.001). Microsatellite data reinforce the conclusion from mtDNA that the Suwannee River population might eventually be recognized as a distinct taxonomic unit. It was the only population showing fixation or near fixation for otherwise rare microsatellite alleles. Six evolutionarily significant units are recommended on the basis of reciprocal mtDNA monophyly and high levels of microsatellite DNA divergence.

  2. Range-wide phylogeographic analysis of the spotted frog complex (Rana luteiventris and Rana pretiosa) in northwestern North America

    USGS Publications Warehouse

    Funk, W.C.; Pearl, C.A.; Draheim, H.M.; Adams, M.J.; Mullins, T.D.; Haig, S.M.

    2008-01-01

    The dynamic geological and climatic history of northwestern North America has made it a focal region for phylogeography. We conducted a range-wide phylogeographic analysis of the spotted frog complex (Rana luteiventris and Rana pretiosa) across its range in northwestern North America to understand its evolutionary history and the distribution of clades to inform conservation of R. pretiosa and Great Basin R. luteiventris, candidates for listing under the US Endangered Species Act. Mitochondrial DNA sequence data from a segment of the cytochrome b gene were obtained from 308 R. luteiventris and R. pretiosa from 96 sites. Phylogenetic analysis revealed one main R. pretiosa clade and three main R. luteiventris clades, two of which overlapped in southeastern Oregon. The three R. luteiventris clades were separated from each other by high levels of sequence divergence (average of 4.75-4.97%). Two divergent clades were also uncovered within the Great Basin. Low genetic variation in R. pretiosa and the southeastern Oregon clade of R. luteiventris suggests concern about their vulnerability to extinction. ?? 2008 Elsevier Inc.

  3. Forecasting the range-wide status of polar bears at selected times in the 21st century

    USGS Publications Warehouse

    Amstrup, Steven C.; Marcot, Bruce G; Douglas, David C.

    2007-01-01

    To inform the U.S. Fish and Wildlife Service decision, whether or not to list polar bears as threatened under the Endangered Species Act (ESA), we forecast the status of the world's polar bear (Urslls maritimus) populations 45, 75 and 100 years into the future. We applied the best available information about predicted changes in sea ice in the 21 st century to current knowledge of polar bear populations and their ecological relationships to the sea ice to understand how the range-wide population of polar bears might change. We combined the world's 19 polar bear subpopulations into 4 ecological regions based on current and projected sea ice conditions. These "ecoregions" are the (1) Seasonal Ice Ecoregion which includes Hudson Bay, and occurs mainly at the southern extreme of the polar bear range, (2) the Archipelago Ecoregion of the Canadian Arctic, (3) the Polar Basin Divergent Ecoregion where ice is formed and then adverted away from near-shore areas, and (4) the Polar Basin Convergent Ecoregion where sea ice formed elsewhere tends to collect against the shore. We mcolporated projections of future sea ice in each ecoregion, based on 10 general circulation models (GCMs), into two models of polar bear habitat and potential population response. First, we used a deterministic model of past, current, and future polar bear carrying capacity which assumed a linear relationship between bear density and annual average sea ice extent. Because this approach did not include seasonal changes in ice availability or other possible population stressors, it provided an optimistic view of the potential magnitude of and change m population carrying capacity by ecoregion and time step. Second, we developed a Bayesian network (BN) model structured around population successors that could affect the factors considered in ESA decisions. The BN model combined empirical data, interpretations of data, and professional judgment into a probabilistic framework. Although BN models can be

  4. Range wide molecular data and niche modeling revealed the Pleistocene history of a global invader (Halyomorpha halys).

    PubMed

    Zhu, Geng-Ping; Ye, Zhen; Du, Juan; Zhang, Dan-Li; Zhen, Ya-hui; Zheng, Chen-guang; Zhao, Li; Li, Min; Bu, Wen-Jun

    2016-01-01

    Invasive species' Pleistocene history contains much information on its present population structure, dispersability and adaptability. In this study, the Pleistocene history of a global invasive pest (Brown Marmorated Stink Bug BMSB, Halyomorpha halys) was unveiled using the coupled approach of phylogeography and ecological niche modelling. Rangewide molecular data suggests that the Taiwan and other native populations had diverged in mid-Pleistocene. In mainland China, the native BMSB did not experience population contraction and divergence during last glacial, but persisted in interconnected populations. Combined Bayesian Skyline Plot (BSP) and niche modelling revealed a rapid expansion occurred during the transition of Last Inter Glacial (LIG) to Last Glacial Maximum (LGM). High genetic diversity and multi-reticular haplotypes network exist in the original sources populations of BMSB invasion in northern China. They were speculated to be colonized from the central China, with many derived haplotypes evolved to adapt the novel environment. The ENM future prediction suggest that BMSB may expand northward to higher latitudes in the US and Europe, because of its high invasive ability, together with the available suitable climate space there. PMID:26996353

  5. Range wide molecular data and niche modeling revealed the Pleistocene history of a global invader (Halyomorpha halys)

    PubMed Central

    Zhu, Geng-Ping; Ye, Zhen; Du, Juan; Zhang, Dan-Li; Zhen, Ya-hui; Zheng, Chen-guang; Zhao, Li; Li, Min; Bu, Wen-Jun

    2016-01-01

    Invasive species’ Pleistocene history contains much information on its present population structure, dispersability and adaptability. In this study, the Pleistocene history of a global invasive pest (Brown Marmorated Stink Bug BMSB, Halyomorpha halys) was unveiled using the coupled approach of phylogeography and ecological niche modelling. Rangewide molecular data suggests that the Taiwan and other native populations had diverged in mid-Pleistocene. In mainland China, the native BMSB did not experience population contraction and divergence during last glacial, but persisted in interconnected populations. Combined Bayesian Skyline Plot (BSP) and niche modelling revealed a rapid expansion occurred during the transition of Last Inter Glacial (LIG) to Last Glacial Maximum (LGM). High genetic diversity and multi-reticular haplotypes network exist in the original sources populations of BMSB invasion in northern China. They were speculated to be colonized from the central China, with many derived haplotypes evolved to adapt the novel environment. The ENM future prediction suggest that BMSB may expand northward to higher latitudes in the US and Europe, because of its high invasive ability, together with the available suitable climate space there. PMID:26996353

  6. Range-wide genetic structure of maritime pine predates the last glacial maximum: evidence from nuclear DNA.

    PubMed

    Naydenov, Krassimir D; Alexandrov, Alexander; Matevski, Vlado; Vasilevski, Kole; Naydenov, Michel K; Gyuleva, Veselka; Carcaillet, Christopher; Wahid, Nadya; Kamary, Salim

    2014-02-01

    Using nuclear simple sequence repeats (nuSSRs), we determined the genetic variability in the natural distribution range of maritime pine (Pinus pinaster) in the western Mediterranean region. We analysed the role of global and significant climatic fluctuations in driving the evolutionary diversification of this species. We attempted to determine the impact of the last glacial maximum (LGM) and human activity on genetic variation and to identify the effect of bottlenecks, admixing, migration, time to the most recent common ancestor (TMRCA), and recent splits. A total of 972 individuals were analysed. The sample represented 27 natural populations from the western Mediterranean region, which encompasses most of the natural range of P. pinaster. Using eight nuSSRs, we analysed genetic diversity indices for each population and group of populations. We also examined the interpopulation structure by the frequency and distance method and investigated genetic barriers, signals of historical demographic fluctuations, phylogeographic structure, admixing, rate of mutation, migration, as well as testing the hypothesis of isolation by distance (IBD). Both cluster analyses showed similar population genetic structure with three genetic barriers that divided the samples into four large groups. Intensive migration was only detected during the period of the last glacial maximum (LGM), which permitted the mutation rate of the markers used to be calculated. The majority of the population was found to exhibit signs of a recent bottleneck and its timing showed a clear northeast-southwest geographic distribution. A clearly defined phylogeographic structure (Nst > Gst and Rst > Gst ) under IBD was established, and showed the highest divergence between groups of populations separated by physical barriers, such as the Strait of Gibraltar, the Mediterranean Sea and the Pyrenees. The high level of intergroup genetic differentiation (ΦIS = 20.26) was attributed to a long historical isolation

  7. A range-wide genetic bottleneck overwhelms contemporary landscape factors and local abundance in shaping genetic patterns of an alpine butterfly (Lepidoptera: Pieridae: Colias behrii).

    PubMed

    Schoville, Sean D; Lam, Athena W; Roderick, George K

    2012-09-01

    Spatial and environmental heterogeneity are major factors in structuring species distributions in alpine landscapes. These landscapes have also been affected by glacial advances and retreats, causing alpine taxa to undergo range shifts and demographic changes. These nonequilibrium population dynamics have the potential to obscure the effects of environmental factors on the distribution of genetic variation. Here, we investigate how demographic change and environmental factors influence genetic variation in the alpine butterfly Colias behrii. Data from 14 microsatellite loci provide evidence of bottlenecks in all population samples. We test several alternative models of demography using approximate Bayesian computation (ABC), with the results favouring a model in which a recent bottleneck precedes rapid population growth. Applying independent calibrations to microsatellite loci and a nuclear gene, we estimate that this bottleneck affected both northern and southern populations 531-281 years ago, coinciding with a period of global cooling. Using regression approaches, we attempt to separate the effects of population structure, geographical distance and landscape on patterns of population genetic differentiation. Only 40% of the variation in F(ST) is explained by these models, with geographical distance and least-cost distance among meadow patches selected as the best predictors. Various measures of genetic diversity within populations are also decoupled from estimates of local abundance and habitat patch characteristics. Our results demonstrate that demographic change can have a disproportionate influence on genetic diversity in alpine species, contrasting with other studies that suggest landscape features control contemporary demographic processes in high-elevation environments. PMID:22849440

  8. Dancing with Demographers.

    ERIC Educational Resources Information Center

    Robertson, Heather-Jane

    2000-01-01

    Demographic projections concerning the shortage of teachers in Canada, their pay scale, the feminization of teaching, the gender gap in salaries, and teacher autonomy have often been incorrect, or correct for the wrong reasons. Instead of relying on demographic predictions, teachers should contemplate who they really want to be professionally,…

  9. Demographics: People and Markets.

    ERIC Educational Resources Information Center

    Merrick, Thomas W.; Tordella, Stephen J.

    1988-01-01

    Population shifts directly affect the bottom line, so the basics of demography are now basic to business as well. Demographics combine demographic data with socioeconomic and geographic factors to help business and other managers know the market for the goods and services they offer. This guide explains market, product, and site analyses,…

  10. The demographics of inequality.

    PubMed

    Pestieau, P

    1989-01-01

    "This paper presents a survey of recent literature on the effects of demographic variables on economic inequality. First, a number of conceptual and methodological questions are raised and discussed. They pertain to what is meant by inequality, what the range of demographic variables is, and how variable and endogenous are the demographic variables most widely used. The paper then turns to a review of empirical works on the distributive incidence of the following demographic variables: baby boomers entering the job market, aging population, variable fertility and mortality rates, internal and external migrations, divorce and widowhood, and finally donations and bequests. It appears that a lot of caution is needed when assessing the incidence of any demographic variable changing the size of the population because in this case standard inequality measures yield conflicting signals." The geographical focus is on developed countries. PMID:12315947

  11. Universal Expansion.

    ERIC Educational Resources Information Center

    McArdle, Heather K.

    1997-01-01

    Describes a week-long activity for general to honors-level students that addresses Hubble's law and the universal expansion theory. Uses a discrepant event-type activity to lead up to the abstract principles of the universal expansion theory. (JRH)

  12. Range-wide network of priority areas for greater sage-grouse - a design for conserving connected distributions or isolating individual zoos?

    USGS Publications Warehouse

    Crist, Michele R.; Knick, Steven T.; Hanser, Steven E.

    2015-01-01

    The network of areas delineated in 11 Western States for prioritizing management of greater sage-grouse (Centrocercus urophasianus) represents a grand experiment in conservation biology and reserve design. We used centrality metrics from social network theory to gain insights into how this priority area network might function. The network was highly centralized. Twenty of 188 priority areas accounted for 80 percent of the total centrality scores. These priority areas, characterized by large size and a central location in the range-wide distribution, are strongholds for greater sage-grouse populations and also might function as sources. Mid-ranking priority areas may serve as stepping stones because of their location between large central and smaller peripheral priority areas. The current network design and conservation strategy has risks. The contribution of almost one-half (n = 93) of the priority areas combined for less than 1 percent of the cumulative centrality scores for the network. These priority areas individually are likely too small to support viable sage-grouse populations within their boundary. Without habitat corridors to connect small priority areas either to larger priority areas or as a clustered group within the network, their isolation could lead to loss of sage-grouse within these regions of the network. 

  13. Range-wide genetic population structure of common pochard (Aythya ferina): a potentially important vector of highly pathogenic avian influenza viruses

    PubMed Central

    Liu, Yang; Keller, Irene; Heckel, Gerald

    2011-01-01

    An understanding of the distribution and spatial structure of the natural vectors of zoonothic pathogens is of interest for effective disease control and prevention. Here, we investigate the range-wide population genetic structure of common pochard (Aythya ferina), a long-distance migratory duck and potential vector of highly pathogenic avian influenza. We collected several hundred samples from breeding and wintering grounds across Eurasia including some H5N1-positive individuals and generated partial sequences of the mitochondrial control region and multilocus microsatellite genotypes. Genetic differentiation among breeding populations was significant for both marker types but higher for maternally inherited mtDNA than for biparentally inherited nuclear markers. There was only weak genetic divergence between ducks sampled in Europe and East Asia, and genetic differentiation between populations was not generally associated with geographical distance. No evidence of genetic substructure was detected for ducks sampled on the European wintering grounds. Our results suggest limited breeding-site fidelity, especially in females, but extensive population admixture on the wintering grounds. The specific role of pochards as natural vectors of zoonotic pathogens and in particular H5N1 remains to be clarified but our results point to wintering grounds as potential hotspots for disease transmission. PMID:22393520

  14. Range-wide genetic population structure of common pochard (Aythya ferina): a potentially important vector of highly pathogenic avian influenza viruses.

    PubMed

    Liu, Yang; Keller, Irene; Heckel, Gerald

    2011-12-01

    An understanding of the distribution and spatial structure of the natural vectors of zoonothic pathogens is of interest for effective disease control and prevention. Here, we investigate the range-wide population genetic structure of common pochard (Aythya ferina), a long-distance migratory duck and potential vector of highly pathogenic avian influenza. We collected several hundred samples from breeding and wintering grounds across Eurasia including some H5N1-positive individuals and generated partial sequences of the mitochondrial control region and multilocus microsatellite genotypes. Genetic differentiation among breeding populations was significant for both marker types but higher for maternally inherited mtDNA than for biparentally inherited nuclear markers. There was only weak genetic divergence between ducks sampled in Europe and East Asia, and genetic differentiation between populations was not generally associated with geographical distance. No evidence of genetic substructure was detected for ducks sampled on the European wintering grounds. Our results suggest limited breeding-site fidelity, especially in females, but extensive population admixture on the wintering grounds. The specific role of pochards as natural vectors of zoonotic pathogens and in particular H5N1 remains to be clarified but our results point to wintering grounds as potential hotspots for disease transmission. PMID:22393520

  15. A Brief Demographic Portrait

    ERIC Educational Resources Information Center

    Nieto, Sonia

    2012-01-01

    This article presents a brief demographic portrait, with particular emphasis on school-related issues, that points to the dire situation of Latino/a education. According to the 2010 Census, the number of Hispanics (the term used in government data) currently was 50,477,594 million, an increase of 43 percent since 2000, making this group the…

  16. DEMOGRAPHIC AND HEALTH SURVEYS

    EPA Science Inventory

    Demographic and Health Surveys are nationally representative household surveys with large sample sizes of between 5,000 and 30,000 households, typically. DHS surveys provide data for a wide range of monitoring and impact evaluation indicators in the areas of population, health, a...

  17. The Demographic Imperative

    ERIC Educational Resources Information Center

    Jordan, Stephen M.

    2009-01-01

    As the United States moves toward becoming a "minority-majority" country, what more can--and should--college presidents and governing boards do to provide low-income students and students of color with a pipeline to high-quality education? Ongoing discourse about shifting demographics locally and nationally must be built into institutions'…

  18. Youth Demographics. Fact Sheet

    ERIC Educational Resources Information Center

    Lopez, Mark Hugo; Marcelo, Karlo Barrios

    2006-01-01

    This fact sheet compares the numbers of 18-25 year-old residents and citizens by gender, race, ethnicity, geographic distribution, marital status, military status, unemployment, educational attainment, and assesses population trends from 1968-2006. It explores such demographic characteristics of young people using data from the March Annual…

  19. China's demographic dilemmas.

    PubMed

    Tien, H Y; Zhang, T; Ping, Y; Li, J; Liang, Z

    1992-06-01

    China's demographic dilemmas are discussed as the demographic surge during the 20th century, the demographic transition, the struggle to regulate fertility, population and development, and prospects for the future. Brief accounts are given of China's household registration system and the efforts in entry into the global economy. There are references, suggested readings, and discussion questions. Ample figures and tables express population growth, birth and death rates, fertility, sex ratios, population projections for these older than 65 and total population, contraception (IUDs, sterilizations, and abortions), abortion ratios, ethnic minority groups, provincial population data for 1990, schools and enrollment, health care resources, selected economic indicators, and availability of selected consumer items (sewing machines, watches, bicycles, electric fans, washers, refrigerators, televisions, radios, and cameras). Population planning has been successful in reducing the birth rate from 35/1000 in the 1950s to 20/1000 in the 1990s. 17 million persons are added annually. The projection for 2000 is 1.3 billion persons. The emphasis of the discussion is on the development and consequences of strict population planning control measures instituted in the 1970s and strengthened in the 1980s. In addition to curbing numbers, the measures have also led to a rapid aging of the population, a marriage squeeze, charges of female infanticide, and international censure. Population pressure is felt in urban areas, and in the labor force, education, and health systems. Industrialization has led to serious deterioration of natural resources. The gap between rural and urban population has widened. PMID:12286597

  20. Expansion Microscopy

    PubMed Central

    Chen, Fei; Tillberg, Paul W.; Boyden, Edward S.

    2014-01-01

    In optical microscopy, fine structural details are resolved by using refraction to magnify images of a specimen. Here we report the discovery that, by synthesizing a swellable polymer network within a specimen, it can be physically expanded, resulting in physical magnification. By covalently anchoring specific labels located within the specimen directly to the polymer network, labels spaced closer than the optical diffraction limit can be isotropically separated and optically resolved, a process we call expansion microscopy (ExM). Thus, this process can be used to perform scalable super-resolution microscopy with diffraction-limited microscopes. We demonstrate ExM with effective ~70 nm lateral resolution in both cultured cells and brain tissue, performing three-color super-resolution imaging of ~107 μm3 of the mouse hippocampus with a conventional confocal microscope. PMID:25592419

  1. Synthesizing Exoplanet Demographics

    NASA Astrophysics Data System (ADS)

    Clanton, Christian

    2016-01-01

    The discovery of thousands of exoplanets has revealed a large diversity of systems, the majority of which look nothing like our own. On the theoretical side, we are able to make ab initio calculations that make predictions about the properties of exoplanets. However, in order to link these predictions with observations, we must construct a statistical census of exoplanet demographics over as broad a range of parameters as possible. Current constraints on exoplanet demographics are typically constructed using the results of individual surveys using a single detection technique, and thus are incomplete. The only way to derive a statistically-complete census that samples a wide region of exoplanet parameter space is to synthesize the results from surveys employing all of the different discovery methods at our disposal. I present the first studies to demonstrate that this is actually possible, and describe a (mostly) de-biased exoplanet census that is constructed from the synthesis of results from microlensing, radial velocity, and direct imaging surveys. I will also discuss future work that will include the results of transit surveys (in particular, Kepler discoveries) to complete the census of exoplanets in our Galaxy, and describe the application of this census to develop the most comprehensive, observationally-constrained models of planet formation and evolution that have been derived to date.

  2. Thermal Expansion

    NASA Astrophysics Data System (ADS)

    Ventura, Guglielmo; Perfetti, Mauro

    All solid materials, when cooled to low temperatures experience a change in physical dimensions which called "thermal contraction" and is typically lower than 1 % in volume in the 4-300 K temperature range. Although the effect is small, it can have a heavy impact on the design of cryogenic devices. The thermal contraction of different materials may vary by as much as an order of magnitude: since cryogenic devices are constructed at room temperature with a lot of different materials, one of the major concerns is the effect of the different thermal contraction and the resulting thermal stress that may occur when two dissimilar materials are bonded together. In this chapter, theory of thermal contraction is reported in Sect. 1.2 . Section 1.3 is devoted to the phenomenon of negative thermal expansion and its applications.

  3. Planet Demographics from Transits

    NASA Astrophysics Data System (ADS)

    Howard, Andrew

    2015-08-01

    From the demographics of planets detected by the Kepler mission, we have learned that there exists approximately one planet per star for planets larger than Earth orbiting inside of 1 AU. We have also learned the relative occurrence of these planets as a function of their orbital periods, sizes, and host star masses and metallicities. In this talk I will review the key statistical findings that the planet size distribution peaks in the range 1-3 times Earth-size, the orbital period distribution is characterized by a power-law cut off at short periods, small planets are more prevalent around small stars, and that approximately 20% of Sun-like stars hosts a planet 1-2 times Earth-size in a habitable zone. Looking forward, I will describe analysis of photometry from the K2 mission that is yielding initial planet discoveries and offering the opportunity to measure planet occurrence in widely separated regions of the galaxy. Finally, I will also discuss recent techniques to discover transiting planets in space-based photometry and to infer planet population properties from the ensemble of detected and non-detected transit signals.

  4. Demographic Trends: Impact on Schools

    ERIC Educational Resources Information Center

    Chong, Sylvia N. Y.; Cheah, Horn Mun

    2010-01-01

    Background: Singapore is experiencing great demographic change. These demographic trends show fewer young people and declining birth rates, greater longevity for ageing generations and an increase in the number of non-Singaporean residents. Statistics also show that more than half of the total population increase in the last decades was…

  5. Demographic perspectives on Saudi Arabia's development.

    PubMed

    Looney, R E

    1985-06-01

    Demographic movements likely to be taking place in Saudi Arabia were hypothesized on the basis of general knowledge. The discussion reports on population size, general Arab demographic patterns, general determinants of fertility, Arab fertility patterns, Saudi fertility patterns, mortality in general, mortality in the Middle East, mortality in Saudi Arabia, Saudi Arabian population growth, immigration, the changing composition of the work force, and third plan targets. Some doubt exists as to the size of Saudi Arabia's population, but there is little question that the total is growing rapidly. This expansion is taking place through stepped up immigration and a relatively high natural growth of indigenous Saudis, but statistics on population size, structure, and on the number of births and deaths leaves the magnitude of a number of important demographic trends in doubt. Yet, considerable evidence exists that several of the Arab countries in the region with fairly good demographic data are likely to have similar demographic patterns. In depth analysis of the demographic dynamics of these countries, particularly Jordan and Kuwait, identified several common elements bearing on several key parameters. Using what Saudi data is available and making comparisons with these neighboring countries, one can, based on expected levels of birth and death rates, indirectly infer the natural growth of Saudi Arabia's population. With several notable exceptions, Saudi Arabia's demographic patterns show a marked similarity to those experienced in the region as a whole. The average rate of population growth in both Saudi Arabia and the Arab region is about 3% a year and in both instances fertility rates are high. The demographic structure of these countries is characterized by the youthfulness of the population. In most of the Arab countries, the population aged 15 years or under accounts for over 48% of the population. The rate of the economically active population is low, ranging from

  6. Regional population expansion in Eucalyptus globulus.

    PubMed

    Yeoh, Suat Hui; Ho, Simon Y W; Thornhill, Andrew H; Foley, William J

    2013-09-01

    Foundation tree species define the structure of forest habitat and influence their ecosystem dynamics. However, there is limited understanding of both the patterns and timing of population fluctuations in foundation trees and how they vary among geographical regions. We have reconstructed the demographic history of five genetically distinct populations of the Tasmanian blue gum (Eucalyptus globulus ssp. globulus) at the species and regional levels, using three nuclear loci sequenced from 104 individuals. Analysis using a Bayesian skyline plot indicated that the species experienced two periods of expansion, commencing in the Pliocene. Regional analyses showed that island populations expanded earlier, but that the rate of expansion was relatively slow when compared to that of the mainland group. This highlights the need for local demographic history to be taken into account when inferring local adaptation for candidate genes. Population growth throughout the Quaternary signals the ability of the species to persist and thrive under the predominantly harsh conditions of this period. PMID:23643971

  7. Demographics and the Rural Ethos.

    ERIC Educational Resources Information Center

    Ward, James G.

    2003-01-01

    Describes the meaning of "rural" and identifies 31 states having a significant rural character. Discusses certain generalizations about rural America. Provides a demographic analysis with school finance implications. Draws implications for rural school finance policy. (Contains 3 tables.)(PKP)

  8. Genetic traces of east-to-west human expansion waves in Eurasia.

    PubMed

    Chaix, Raphaëlle; Austerlitz, Frédéric; Hegay, Tatyana; Quintana-Murci, Lluís; Heyer, Evelyne

    2008-07-01

    In this study, we describe the landscape of human demographic expansions in Eurasia using a large continental Y chromosome and mitochondrial DNA dataset. Variation at these two uniparentally-inherited genetic systems retraces expansions that occurred in the past 60 ky, and shows a clear decrease of expansion ages from east to west Eurasia. To investigate the demographic events at the origin of this westward decrease of expansion ages, the estimated divergence ages between Eurasian populations are compared with the estimated expansion ages within each population. Both markers suggest that the demographic expansion diffused from east to west in Eurasia in a demic way, i.e., through migrations of individuals (and not just through diffusion of new technologies), highlighting the prominent role of eastern regions within Eurasia during Palaeolithic times. PMID:18324635

  9. Social Demographic Change and Autism

    PubMed Central

    LIU, KAYUET; ZERUBAVEL, NOAM; BEARMAN, PETER

    2010-01-01

    Parental age at child’s birth—which has increased for U.S. children in the 1992–2000 birth cohorts—is strongly associated with an increased risk of autism. By turning a social demographic lens on the historical patterning of concordance among twin pairs, we identify a central mechanism for this association: de novo mutations, which are deletions, insertions, and duplications of DNA in the germ cells that are not present in the parents’ DNA. Along the way, we show that a demographic eye on the rising prevalence of autism leads to three major discoveries. First, the estimated heritability of autism has been dramatically overstated. Second, heritability estimates can change over remarkably short periods of time because of increases in germ cell mutations. Third, social demographic change can yield genetic changes that, at the population level, combine to contribute to the increased prevalence of autism. PMID:20608100

  10. DEMOGRAPHIC DATA FOR CENSUS 2000

    EPA Science Inventory

    This data layer represents Census 2000 demographic data derived from the PL94-171 redistricting files and SF3. Census geographic entities include blocks, blockgroups and tracts. Tiger line files are the source of the geometry representing the Census blocks. Attributes include ...

  11. Enrollment Management: Demographic Changes. Report.

    ERIC Educational Resources Information Center

    Gribbons, Barry C.; Meuschke, Daylene M.

    The Office of Institutional Development and Technology and the Public Information Office created this report that identifies several topics of research in order to inform marketing efforts associated with enrollment management. The report is based upon demographic studies done at the College of Canyons to measure things such as changes in the size…

  12. Are Demographics the Nation's Destiny?

    ERIC Educational Resources Information Center

    Glass, Gene V.

    2008-01-01

    In this article, the author discusses the demographic trends affecting America's public schools. As an expert on empirical evaluation of education, the author believes the major debates over vouchers, charter schools, bilingual education, and other issues are not really about preparing the next generation to compete with China or India, or about…

  13. Demographic Modelling in Weed Biocontrol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Demographic matrix modeling of plant populations can be a powerful tool to identify key life stage transitions that contribute the most to population growth of an invasive plant and hence should be targeted for disruption. Therefore, this approach has the potential to guide the pre-release selection...

  14. Adult Education; State Demographic Data.

    ERIC Educational Resources Information Center

    National Advisory Council on Adult Education, Washington, DC.

    In order to clearly identify the target population of Federal activities in adult education, the Research Committee gathered State-by-State demographic information from the 1970 U.S. Census. This compilation of over 3,700 separate figures provides a profile of adults relating to an eligible population for a Federal-State-Local partnership program.…

  15. America's Changing Population: Demographic Trends.

    ERIC Educational Resources Information Center

    Morrison, Peter A.

    1981-01-01

    Surveys the importance of migration trends in the United States away from the Northeastern urban areas into the sunbelt states of the West and Southwest. Emphasis is placed on ways in which this demographic transformation disturbs social, economic, and political arrangements. (DB)

  16. Demographic Challenges in America's Future.

    ERIC Educational Resources Information Center

    Butz, William P.; And Others

    This document examines trends in the United States population since World War II, and projects a scenario of how demographic and economic phenomena may evolve over the next several decades. The report is divided into five sections. Section 1 introduces the volume and discusses generally some of the effects of the nation's transition to zero…

  17. Demographics.

    PubMed

    Gillis, Artha J; Bath, Eraka

    2016-01-01

    There is a large proportion of minority youth involved in the juvenile justice system. Disproportionate minority contact (DMC) occurs when the proportion of any ethnic group is higher at any given stage in the juvenile justice process than the proportion of this group in the general population. There are several theories explaining the presence and persistence of DMC. This article reviews the history of DMC and the theories and implications of this problem. It discusses several targets for interventions designed to reduce DMC and offer resources in this area. PMID:26593114

  18. Demographics

    MedlinePlus Videos and Cool Tools

    ... tinnitus, making it one of the most common health conditions in the United States. Each year, the U.S. Centers for Disease Control conducts its National Health and Nutritional Examinations Survey , a longitudinal study of ...

  19. Demographic Events and Evolutionary Forces Shaping European Genetic Diversity

    PubMed Central

    Veeramah, Krishna R.; Novembre, John

    2014-01-01

    Europeans have been the focus of some of the largest studies of genetic diversity in any species to date. Recent genome-wide data have reinforced the hypothesis that present-day European genetic diversity is strongly correlated with geography. The remaining challenge now is to understand more precisely how patterns of diversity in Europe reflect ancient demographic events such as postglacial expansions or the spread of farming. It is likely that recent advances in paleogenetics will give us some of these answers. There has also been progress in identifying specific segments of European genomes that reflect adaptations to selective pressures from the physical environment, disease, and dietary shifts. A growing understanding of how modern European genetic diversity has been shaped by demographic and evolutionary forces is not only of basic historical and anthropological interest but also aids genetic studies of disease. PMID:25059709

  20. Demographic events and evolutionary forces shaping European genetic diversity.

    PubMed

    Veeramah, Krishna R; Novembre, John

    2014-09-01

    Europeans have been the focus of some of the largest studies of genetic diversity in any species to date. Recent genome-wide data have reinforced the hypothesis that present-day European genetic diversity is strongly correlated with geography. The remaining challenge now is to understand more precisely how patterns of diversity in Europe reflect ancient demographic events such as postglacial expansions or the spread of farming. It is likely that recent advances in paleogenetics will give us some of these answers. There has also been progress in identifying specific segments of European genomes that reflect adaptations to selective pressures from the physical environment, disease, and dietary shifts. A growing understanding of how modern European genetic diversity has been shaped by demographic and evolutionary forces is not only of basic historical and anthropological interest but also aids genetic studies of disease. PMID:25059709

  1. War and the demographic trap.

    PubMed

    Last, J M

    1993-08-28

    Advice is offered on alleviating environmental damage and the suffering of women and children from the effects of war. It is postured that the demographic trap, which was described by King and Elliott, is responsible for environmental stress and many wars. The surface cause may be identified as ideology, politics, or ethnicity, but as in the case of Bosnia, the "ethnic cleansing" makes farmland available to sustain expanding Serbian or Croatian populations. If the land is environmentally damaged by war, then there is little hope of sustainable development. Conflicts in many countries have driven people to urban areas or periurban slums because of displacement and the failure of subsistence economics. Mortality from wars has reached more than a 100 million since the early 1990s. A comparable number have died indirectly from famine and disease associated with the disruption of agriculture and infrastructure from wars. Since 1945, 66-75% of mortality victims have been civilians, of whom 15 million have been women and children. In 1993, there were at least 30 conflicts ongoing throughout the world. Not all of these conflicts are as "ferocious" as the Bosnian conflict, but these "so called low intensity wars" nonetheless disrupt and kill. The manifestations of the demographic trap can be alleviated through interventions that focus on multisectoral aid and conflict resolution. There must be a cooperative effort on the part of health workers, agricultural scientists, mediators, and development personnel. Unfortunately, the amount of development assistance from Europe and America has been reduced in recent years. The recession has affected the provision of international aid. African nations, in particular, have been affected, yet these countries remain the neediest in the world. It would appear that aid agencies have given up hope that the demographic trap can be closed. Population growth must be limited, as the only hope for relieving environmental stress, ecological

  2. Demographic history of India and mtDNA-sequence diversity.

    PubMed Central

    Mountain, J L; Hebert, J M; Bhattacharyya, S; Underhill, P A; Ottolenghi, C; Gadgil, M; Cavalli-Sforza, L L

    1995-01-01

    The demographic history of India was examined by comparing mtDNA sequences obtained from members of three culturally divergent Indian subpopulations (endogamous caste groups). While an inferred tree revealed some clustering according to caste affiliation, there was no clear separation into three genetically distinct groups along caste lines. Comparison of pairwise nucleotide difference distributions, however, did indicate a difference in growth patterns between two of the castes. The Brahmin population appears to have undergone either a rapid expansion or steady growth. The low-ranking Mukri caste, however, may have either maintained a roughly constant population size or undergone multiple bottlenecks during that period. Comparison of the Indian sequences to those obtained from other populations, using a tree, revealed that the Indian sequences, along with all other non-African samples, form a starlike cluster. This cluster may represent a major expansion, possibly originating in southern Asia, taking place at some point after modern humans initially left Africa. PMID:7717409

  3. The Stratification of Students in Israeli Universities: Persistent Outcomes of an Educational Expansion Policy

    ERIC Educational Resources Information Center

    Yogev, Abraham

    2007-01-01

    Expansion trends of higher education systems involve the planned growth of new universities, frequently stratified lower than established ones in academic breadth and excellence as well as in the socio-demographic origins of their students. The persistence of this internal stratification of the university system subsequent to its expansion remains…

  4. Demographics, Affect, and Adolescents' Health Behaviors.

    ERIC Educational Resources Information Center

    Terre, Lisa; And Others

    1992-01-01

    Examined relationship between affect, demographics, and health-related lifestyle among 139 public high school students. Data analyses revealed distinctive demographic and affective correlates of different health behaviors. No one variable uniformly predicted adolescents' health behaviors. Demographics and affect showed differential relationships…

  5. Demographic Consequences of Defeating Aging

    PubMed Central

    Gavrilova, Natalia S.

    2010-01-01

    Abstract A common objection against starting a large-scale biomedical war on aging is the fear of catastrophic population consequences (overpopulation). This fear is only exacerbated by the fact that no detailed demographic projections for radical life extension scenario have been conducted so far. This study explores different demographic scenarios and population projections, in order to clarify what could be the demographic consequences of a successful biomedical war on aging. A general conclusion of this study is that population changes are surprisingly slow in their response to a dramatic life extension. For example, we applied the cohort-component method of population projections to 2005 Swedish population for several scenarios of life extension and a fertility schedule observed in 2005. Even for very long 100-year projection horizon, with the most radical life extension scenario (assuming no aging at all after age 60), the total population increases by 22% only (from 9.1 to 11.0 million). Moreover, if some members of society reject to use new anti-aging technologies for some religious or any other reasons (inconvenience, non-compliance, fear of side effects, costs, etc.), then the total population size may even decrease over time. Thus, even in the case of the most radical life extension scenario, population growth could be relatively slow and may not necessarily lead to overpopulation. Therefore, the real concerns should be placed not on the threat of catastrophic population consequences (overpopulation), but rather on such potential obstacles to a success of biomedical war on aging, as scientific, organizational, and financial limitations. PMID:20426616

  6. Evolutionary shaping of demographic schedules

    PubMed Central

    Wachter, Kenneth W.; Steinsaltz, David; Evans, Steven N.

    2014-01-01

    Evolutionary processes of natural selection may be expected to leave their mark on age patterns of survival and reproduction. Demographic theory includes three main strands—mutation accumulation, stochastic vitality, and optimal life histories. This paper reviews the three strands and, concentrating on mutation accumulation, extends a mathematical result with broad implications concerning the effect of interactions between small age-specific effects of deleterious mutant alleles. Empirical data from genomic sequencing along with prospects for combining strands of theory hold hope for future progress. PMID:25024186

  7. Demographic responses and population change.

    PubMed

    Friedlander, D

    1969-11-01

    Most Western societies have gone through a process of population change during the past 100-150 years. One important aspect is the socalled demographic transition: the shift from high to low birth and death rates, and accelerated growth resulting from the lag between falling mortality and falling fertility, in national populations. Equally important has been the "rural-to-urban" transition, which involved the migration of millions of people from rural areas. It is hypothesized, following the suggestion of Davis (Theory of the Multi-Phasic Demographic Response), that the adjustment in reproductive behavior made by a community in response to a rising "strain," such as that resulting from higher natural increase, is likely to differ depending upon the ease with which the community can relieve the strain through out migration. Relationships among such characteristics of modernization as intensity of industrialization, speed of urbanization, structural changes in the agricultural system, and declining fertility are implied. Case studies of England and Sweden lend support to the hypothesis: more rapid urban-industrial development, larger-scale movement from rural areas, and a delayed decline in the rural birth rate distinguish the English transition. PMID:21279792

  8. Alcohol Consumption in Demographic Subpopulations

    PubMed Central

    Delker, Erin; Brown, Qiana; Hasin, Deborah S.

    2016-01-01

    Alcohol consumption is common across subpopulations in the United States. However, the health burden associated with alcohol consumption varies across groups, including those defined by demographic characteristics such as age, race/ethnicity, and gender. Large national surveys, such as the National Epidemiologic Survey on Alcohol and Related Conditions and the National Survey on Drug Use and Health, found that young adults ages 18–25 were at particularly high risk of alcohol use disorder and unintentional injury caused by drinking. These surveys furthermore identified significant variability in alcohol consumption and its consequences among racial/ethnic groups. White respondents reported the highest prevalence of current alcohol consumption, whereas alcohol abuse and dependence were most prevalent among Native Americans. Native Americans and Blacks also were most vulnerable to alcohol-related health consequences. Even within ethnic groups, there was variability between and among different subpopulations. With respect to gender, men reported more alcohol consumption and binge drinking than women, especially in older cohorts. Men also were at greater risk of alcohol abuse and dependence, liver cirrhosis, homicide after alcohol consumption, and drinking and driving. Systematic identification and measurement of the variability across demographics will guide prevention and intervention efforts, as well as future research. PMID:27159807

  9. [Healthcare expenditures growth: the red herring of demographic ageing?].

    PubMed

    Tenand, Marianne

    2016-02-01

    Demographic ageing is often deemed responsible for the massive increase in health expenditures experienced by developed countries. As the elderly consume more medical care than the rest of the population, how could the increase in the share of the 60 + not lead to a marked expansion of healthcare public and private budgets? Despite its apparent logics, such reasoning is fallacious: it ignores that medical care consumption depends on many factors beyond age, which have tremendously evolved in the last decades and may change again in the future. Based on French stylized facts, this article provides an overview of the international literature that aimed at disentangling the respective roles of population ageing and of the non-demographic factors in explaining the dynamics of health expenditures. Paradoxically, technical medical progress has been a major contributor to the increase of healthcare spending. Results from economics research lead to qualify the impact of demographic trends and call for more attention to the public policies decisions that shape healthcare systems. PMID:26936179

  10. Pen Branch delta expansion

    SciTech Connect

    Nelson, E.A.; Christensen, E.J.; Mackey, H.E.; Sharitz, R.R.; Jensen, J.R.; Hodgson, M.E.

    1984-02-01

    Since 1954, cooling water discharges from K Reactor ({anti X} = 370 cfs {at} 59 C) to Pen Branch have altered vegetation and deposited sediment in the Savannah River Swamp forming the Pen Branch delta. Currently, the delta covers over 300 acres and continues to expand at a rate of about 16 acres/yr. Examination of delta expansion can provide important information on environmental impacts to wetlands exposed to elevated temperature and flow conditions. To assess the current status and predict future expansion of the Pen Branch delta, historic aerial photographs were analyzed using both basic photo interpretation and computer techniques to provide the following information: (1) past and current expansion rates; (2) location and changes of impacted areas; (3) total acreage presently affected. Delta acreage changes were then compared to historic reactor discharge temperature and flow data to see if expansion rate variations could be related to reactor operations.

  11. Weakly relativistic plasma expansion

    SciTech Connect

    Fermous, Rachid Djebli, Mourad

    2015-04-15

    Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.

  12. Thermal Expansion "Paradox."

    ERIC Educational Resources Information Center

    Fakhruddin, Hasan

    1993-01-01

    Describes a paradox in the equation for thermal expansion. If the calculations for heating a rod and subsequently cooling a rod are determined, the new length of the cool rod is shorter than expected. (PR)

  13. [Population and crisis. Economic inflexibility or demographic subordination].

    PubMed

    Morelos, J B

    1989-01-01

    Much speculation, fact-based and subjective, has centered on the links between population and economic crisis, and between population and progress. In the past, famines directly affected the size and dynamics of population in affected regions, and such cycles inspired theories that regarded subsistence as the adjustment mechanism for demographic regimes. Population has alternatively been viewed as a crucial factor of production and a force for modernization and progress. After World War I and the Great Depression, many economists believed that population growth would be indispensable for renewing economic expansion. The favorable view of population growth in Mexico led to measures to repatriate emigrants, attract immigrants, and improve health conditions. The gross national product grew by around 6.0% annually on average between 1940 and 1960, and the per capita GNP by about 3%. Demographic dynamics acquired momentum by the 1960s, with high growth rates, a young age structure, considerable demographic inertia, and relative predominance of the urban population. Indications began to appear that a primarily economic solution to achieving full development would be unlikely. The polarization of development, distributive insufficiency, distortions in exchange relations for agricultural products, and incorporation of inappropriate technologies were factors decreasing the ability of the economy to respond adequately to population demands. National development was insufficient to meet growing demographic pressures in the labor market, educational system, housing, and urban services. The adjustment programs reduced even further the flexibility of the government to respond to pressures. Expectations for the future have been seriously compromised by the fall of real incomes. PMID:12158103

  14. [Implications of demographic aging for welfare planning].

    PubMed

    Han Chande, R

    1998-01-01

    The implications of demographic aging for the future planning of socioeconomic welfare for the elderly in Mexico are considered. The inevitability of the demographic aging process is first established. Next, the relationship between demographic aging and development is considered. Finally, the author spells out the problems of providing for the needs of the elderly, particularly in the area of social security and health. PMID:12349179

  15. The Importance of Demographic Data in Astronomy

    NASA Astrophysics Data System (ADS)

    Elmegreen, Debra M.

    2014-01-01

    The most effective astronomical workforce will be one that comprises a diverse and inclusive community. The “New Worlds, New Horizons in Astronomy and Astrophysics” Decadal Survey, with input from its Infrastructure Study Group on Demographics, provided an overview of recent demographic trends. Demographics in astronomy have undergone significant changes over the past two generations in several, but not all, categories. Maintaining records of demographics regarding age, gender, and minority status, as well as trends by discipline and career choices, is vital in planning for the future training and employment of astronomers.

  16. Accelerating the loop expansion

    SciTech Connect

    Ingermanson, R.

    1986-07-29

    This thesis introduces a new non-perturbative technique into quantum field theory. To illustrate the method, I analyze the much-studied phi/sup 4/ theory in two dimensions. As a prelude, I first show that the Hartree approximation is easy to obtain from the calculation of the one-loop effective potential by a simple modification of the propagator that does not affect the perturbative renormalization procedure. A further modification then susggests itself, which has the same nice property, and which automatically yields a convex effective potential. I then show that both of these modifications extend naturally to higher orders in the derivative expansion of the effective action and to higher orders in the loop-expansion. The net effect is to re-sum the perturbation series for the effective action as a systematic ''accelerated'' non-perturbative expansion. Each term in the accelerated expansion corresponds to an infinite number of terms in the original series. Each term can be computed explicitly, albeit numerically. Many numerical graphs of the various approximations to the first two terms in the derivative expansion are given. I discuss the reliability of the results and the problem of spontaneous symmetry-breaking, as well as some potential applications to more interesting field theories. 40 refs.

  17. [Demographic development of the population].

    PubMed

    Diepgen, Thomas L

    2005-09-01

    During the last century the median life expectation age was lengthened about 30 years in Germany. According to recent prognoses this trend will continue over the next decades. Not only the number of people older than 60 years but also its percentage within the population was and will be increasing dramatically. This has important socio-economic, political and health-economic consequences. The increasing older population has an important impact on Dermatology. The incidence of many skin diseases is increasing with age due to life long exposure (e. g. UV-light), and aging processes are affecting the skin, its functions and immunology. Last not least, the distinction between skin disease and "cosmetic" skin problems has changed in the past decades in our society. Even a small reduction in the threshold of what the public and health professionals regard as a skin complaint worthy of medical attention could lead to a large increase in future dermatology service requirements. The demographic changes in our society are becoming an important issue in dermatological health care research. PMID:16117743

  18. Blazar Demographics Using Multiwavelength Data

    NASA Astrophysics Data System (ADS)

    Mao, Peiyuan; Massaro, F.; Urry, C. Megan

    2016-01-01

    Blazars are ideal laboratories to study relativistic jets in AGN, which are thought to be an important channel for feeding energy into galaxies and clusters. We present multi-wavelength SEDs of 2214 blazars with known redshifts, based on the Roma-BZCAT data across 12 frequency bands ranging from radio to gamma-ray. We confirm the anti-correlation between radio luminosity and synchrotron peak frequency, (part of what defines the "blazar sequence"), although with greater scatter than seen previously in studies of far fewer blazars. We describe an empirical estimator of luminosities in those 12 frequency bands using only the radio luminosity at 1.4 GHz and the redshift as inputs. Using this estimator, we study the demographics of blazars by comparing Monte-Carlo simulations to blazar surveys at several different frequencies and flux limits. We recover the observed evolutionary parameter for both low-frequency peaked (V/Vmax≈0.6) and high-frequency peaked (V/Vmax≈0.4) blazars, proving that selection effects cause the high-frequency-peaked sources to appear to anti-evolve even though the same underlying evolution was assumed in the simulation. We also show that the if instead we randomly assign fluxes independent of radio luminosity, the simulated blazar samples disagree strongly with the observed ones. These simulations confirm that luminosity and SED shape must indeed be linked in a physical blazar sequence.

  19. Thermal expansion in nanoresonators

    NASA Astrophysics Data System (ADS)

    Mancardo Viotti, Agustín; Monastra, Alejandro G.; Moreno, Mariano F.; Florencia Carusela, M.

    2016-08-01

    Inspired by some recent experiments and numerical works related to nanoresonators, we perform classical molecular dynamics simulations to investigate the thermal expansion and the ability of the device to act as a strain sensor assisted by thermally-induced vibrations. The proposed model consists in a chain of atoms interacting anharmonically with both ends clamped to thermal reservoirs. We analyze the thermal expansion and resonant frequency shifts as a function of temperature and the applied strain. For the transversal modes the shift is approximately linear with strain. We also present analytical results from canonical calculations in the harmonic approximation showing that thermal expansion is uniform along the device. This prediction also works when the system operates in a nonlinear oscillation regime at moderate and high temperatures.

  20. Novel Foraminal Expansion Technique

    PubMed Central

    Senturk, Salim; Ciplak, Mert; Oktenoglu, Tunc; Sasani, Mehdi; Egemen, Emrah; Yaman, Onur; Suzer, Tuncer

    2016-01-01

    The technique we describe was developed for cervical foraminal stenosis for cases in which a keyhole foraminotomy would not be effective. Many cervical stenosis cases are so severe that keyhole foraminotomy is not successful. However, the technique outlined in this study provides adequate enlargement of an entire cervical foraminal diameter. This study reports on a novel foraminal expansion technique. Linear drilling was performed in the middle of the facet joint. A small bone graft was placed between the divided lateral masses after distraction. A lateral mass stabilization was performed with screws and rods following the expansion procedure. A cervical foramen was linearly drilled medially to laterally, then expanded with small bone grafts, and a lateral mass instrumentation was added with surgery. The patient was well after the surgery. The novel foraminal expansion is an effective surgical method for severe foraminal stenosis. PMID:27559460

  1. Optimal Electric Utility Expansion

    Energy Science and Technology Software Center (ESTSC)

    1989-10-10

    SAGE-WASP is designed to find the optimal generation expansion policy for an electrical utility system. New units can be automatically selected from a user-supplied list of expansion candidates which can include hydroelectric and pumped storage projects. The existing system is modeled. The calculational procedure takes into account user restrictions to limit generation configurations to an area of economic interest. The optimization program reports whether the restrictions acted as a constraint on the solution. All expansionmore » configurations considered are required to pass a user supplied reliability criterion. The discount rate and escalation rate are treated separately for each expansion candidate and for each fuel type. All expenditures are separated into local and foreign accounts, and a weighting factor can be applied to foreign expenditures.« less

  2. Novel Foraminal Expansion Technique.

    PubMed

    Ozer, Ali Fahir; Senturk, Salim; Ciplak, Mert; Oktenoglu, Tunc; Sasani, Mehdi; Egemen, Emrah; Yaman, Onur; Suzer, Tuncer

    2016-08-01

    The technique we describe was developed for cervical foraminal stenosis for cases in which a keyhole foraminotomy would not be effective. Many cervical stenosis cases are so severe that keyhole foraminotomy is not successful. However, the technique outlined in this study provides adequate enlargement of an entire cervical foraminal diameter. This study reports on a novel foraminal expansion technique. Linear drilling was performed in the middle of the facet joint. A small bone graft was placed between the divided lateral masses after distraction. A lateral mass stabilization was performed with screws and rods following the expansion procedure. A cervical foramen was linearly drilled medially to laterally, then expanded with small bone grafts, and a lateral mass instrumentation was added with surgery. The patient was well after the surgery. The novel foraminal expansion is an effective surgical method for severe foraminal stenosis. PMID:27559460

  3. Demographics and Education: The 20 Richest Countries

    ERIC Educational Resources Information Center

    Marchant, Gregory J.; Johnson, Jessica J.

    2012-01-01

    This paper explores the PISA [Programme for International Student Assessment] achievement of twenty countries in light of some of their demographic differences. SES [student socioeconomic status], nuclear family, gender, home language, and native status were predictive of achievement for every country. Demographics accounted for as little as 8…

  4. The Unaddressed Costs of Changing Student Demographics

    ERIC Educational Resources Information Center

    Kaplan, Leslie S.; Owings, William A.

    2013-01-01

    This article discusses the impact of changing student demographics on financing education and on our national wellbeing. We begin by examining the research of current student demographics and their relationship to learning and education costs. We then calculate a 1% cost factor from the average per-pupil expenditure based on the 2011 "Digest…

  5. A Demographic Perspective on Family Change

    PubMed Central

    Bianchi, Suzanne M.

    2014-01-01

    Demographic analysis seeks to understand how individual microlevel decisions about child-bearing, marriage and partnering, geographic mobility, and behaviors that influence health and longevity aggregate to macrolevel population trends and differentials in fertility, mortality and migration. In this review, I first discuss theoretical perspectives—classic demographic transition theory, the perspective of the “second demographic transition,” the spread of developmental idealism—that inform demographers’ understanding of macrolevel population change. Then, I turn to a discussion of the role that demographically informed data collection has played in illuminating family change since the mid-20th century in the United States. Finally, I discuss ways in which demographic theory and data collection might inform future areas of family research, particularly in the area of intergenerational family relationships and new and emerging family forms. PMID:26078785

  6. Urban Expansion Study

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Under an Egyptian government contract, PADCO studies urban growth in the Nile Area. They were assisted by LANDSAT survey maps and measurements provided by TAC. TAC had classified the raw LANDSAT data and processed it into various categories to detail urban expansion. PADCO crews spot checked the results, and correlations were established.

  7. A Special Trinomial Expansion

    ERIC Educational Resources Information Center

    Ayoub, Ayoub B.

    2006-01-01

    In this article, the author takes up the special trinomial (1 + x + x[squared])[superscript n] and shows that the coefficients of its expansion are entries of a Pascal-like triangle. He also shows how to calculate these entries recursively and explicitly. This article could be used in the classroom for enrichment. (Contains 1 table.)

  8. Static gas expansion cooler

    DOEpatents

    Guzek, J.C.; Lujan, R.A.

    1984-01-01

    Disclosed is a cooler for television cameras and other temperature sensitive equipment. The cooler uses compressed gas ehich is accelerated to a high velocity by passing it through flow passageways having nozzle portions which expand the gas. This acceleration and expansion causes the gas to undergo a decrease in temperature thereby cooling the cooler body and adjacent temperature sensitive equipment.

  9. Expansion of Pannes

    EPA Science Inventory

    For the Long Island, New Jersey, and southern New England region, one facet of marsh drowning as a result of accelerated sea level rise is the expansion of salt marsh ponds and pannes. Over the past century, marsh ponds and pannes have formed and expanded in areas of poor drainag...

  10. AUTO-EXPANSIVE FLOW

    EPA Science Inventory

    Physics suggests that the interplay of momentum, continuity, and geometry in outward radial flow must produce density and concomitant pressure reductions. In other words, this flow is intrinsically auto-expansive. It has been proposed that this process is the key to understanding...

  11. The influence of interspecific interactions on species range expansion rates

    PubMed Central

    Svenning, Jens-Christian; Gravel, Dominique; Holt, Robert D.; Schurr, Frank M.; Thuiller, Wilfried; Münkemüller, Tamara; Schiffers, Katja H.; Dullinger, Stefan; Edwards, Thomas C.; Hickler, Thomas; Higgins, Steven I.; Nabel, Julia E. M. S.; Pagel, Jörn; Normand, Signe

    2014-01-01

    Ongoing and predicted global change makes understanding and predicting species’ range shifts an urgent scientific priority. Here, we provide a synthetic perspective on the so far poorly understood effects of interspecific interactions on range expansion rates. We present theoretical foundations for how interspecific interactions may modulate range expansion rates, consider examples from empirical studies of biological invasions and natural range expansions as well as process-based simulations, and discuss how interspecific interactions can be more broadly represented in process-based, spatiotemporally explicit range forecasts. Theory tells us that interspecific interactions affect expansion rates via alteration of local population growth rates and spatial displacement rates, but also via effects on other demographic parameters. The best empirical evidence for interspecific effects on expansion rates comes from studies of biological invasions. Notably, invasion studies indicate that competitive dominance and release from specialized enemies can enhance expansion rates. Studies of natural range expansions especially point to the potential for competition from resident species to reduce expansion rates. Overall, it is clear that interspecific interactions may have important consequences for range dynamics, but also that their effects have received too little attention to robustly generalize on their importance. We then discuss how interspecific interactions effects can be more widely incorporated in dynamic modeling of range expansions. Importantly, models must describe spatiotemporal variation in both local population dynamics and dispersal. Finally, we derive the following guidelines for when it is particularly important to explicitly represent interspecific interactions in dynamic range expansion forecasts: if most interacting species show correlated spatial or temporal trends in their effects on the target species, if the number of interacting species is low

  12. The influence of interspecific interactions on species range expansion rates

    USGS Publications Warehouse

    Svenning, Jens-Christian; Gravel, Dominique; Holt, Robert D.; Schurr, Frank M.; Thuiller, Wilfried; Münkemüller, Tamara; Schiffers, Katja H.; Dullinger, Stefan; Edwards, Thomas C., Jr.; Hickler, Thomas; Higgins, Steven I.; Nabel, Julia E.M.S.; Pagel, Jörn; Normand, Signe

    2014-01-01

    Ongoing and predicted global change makes understanding and predicting species’ range shifts an urgent scientific priority. Here, we provide a synthetic perspective on the so far poorly understood effects of interspecific interactions on range expansion rates. We present theoretical foundations for how interspecific interactions may modulate range expansion rates, consider examples from empirical studies of biological invasions and natural range expansions as well as process-based simulations, and discuss how interspecific interactions can be more broadly represented in process-based, spatiotemporally explicit range forecasts. Theory tells us that interspecific interactions affect expansion rates via alteration of local population growth rates and spatial displacement rates, but also via effects on other demographic parameters. The best empirical evidence for interspecific effects on expansion rates comes from studies of biological invasions. Notably, invasion studies indicate that competitive dominance and release from specialized enemies can enhance expansion rates. Studies of natural range expansions especially point to the potential for competition from resident species to reduce expansion rates. Overall, it is clear that interspecific interactions may have important consequences for range dynamics, but also that their effects have received too little attention to robustly generalize on their importance. We then discuss how interspecific interactions effects can be more widely incorporated in dynamic modeling of range expansions. Importantly, models must describe spatiotemporal variation in both local population dynamics and dispersal. Finally, we derive the following guidelines for when it is particularly important to explicitly represent interspecific interactions in dynamic range expansion forecasts: if most interacting species show correlated spatial or temporal trends in their effects on the target species, if the number of interacting species is low

  13. Genetic footprints reveal geographic patterns of expansion in Fennoscandian red foxes.

    PubMed

    Norén, Karin; Statham, Mark J; Ågren, Erik O; Isomursu, Marja; Flagstad, Øystein; Eide, Nina E; Berg, Thomas Bjørneboe G; Bech-Sanderhoff, Lene; Sacks, Benjamin N

    2015-09-01

    Population expansions of boreal species are among the most substantial ecological consequences of climate change, potentially transforming both structure and processes of northern ecosystems. Despite their importance, little is known about expansion dynamics of boreal species. Red foxes (Vulpes vulpes) are forecasted to become a keystone species in northern Europe, a process stemming from population expansions that began in the 19th century. To identify the relative roles of geographic and demographic factors and the sources of northern European red fox population expansion, we genotyped 21 microsatellite loci in modern and historical (1835-1941) Fennoscandian red foxes. Using Bayesian clustering and Bayesian inference of migration rates, we identified high connectivity and asymmetric migration rates across the region, consistent with source-sink dynamics, whereby more recently colonized sampling regions received immigrants from multiple sources. There were no clear clines in allele frequency or genetic diversity as would be expected from a unidirectional range expansion from south to north. Instead, migration inferences, demographic models and comparison to historical red fox genotypes suggested that the population expansion of the red fox is a consequence of dispersal from multiple sources, as well as in situ demographic growth. Together, these findings provide a rare glimpse into the anatomy of a boreal range expansion and enable informed predictions about future changes in boreal communities. PMID:26058388

  14. Expansion tube test time predictions

    NASA Technical Reports Server (NTRS)

    Gourlay, Christopher M.

    1988-01-01

    The interaction of an interface between two gases and strong expansion is investigated and the effect on flow in an expansion tube is examined. Two mechanisms for the unsteady Pitot-pressure fluctuations found in the test section of an expansion tube are proposed. The first mechanism depends on the Rayleigh-Taylor instability of the driver-test gas interface in the presence of a strong expansion. The second mechanism depends on the reflection of the strong expansion from the interface. Predictions compare favorably with experimental results. The theory is expected to be independent of the absolute values of the initial expansion tube filling pressures.

  15. Bigravity from gradient expansion

    NASA Astrophysics Data System (ADS)

    Yamashita, Yasuho; Tanaka, Takahiro

    2016-05-01

    We discuss how the ghost-free bigravity coupled with a single scalar field can be derived from a braneworld setup. We consider DGP two-brane model without radion stabilization. The bulk configuration is solved for given boundary metrics, and it is substituted back into the action to obtain the effective four-dimensional action. In order to obtain the ghost-free bigravity, we consider the gradient expansion in which the brane separation is supposed to be sufficiently small so that two boundary metrics are almost identical. The obtained effective theory is shown to be ghost free as expected, however, the interaction between two gravitons takes the Fierz-Pauli form at the leading order of the gradient expansion, even though we do not use the approximation of linear perturbation. We also find that the radion remains as a scalar field in the four-dimensional effective theory, but its coupling to the metrics is non-trivial.

  16. Population genetic structure and demographic history of the black fly vector, Simulium nodosum in Thailand.

    PubMed

    Chaiyasan, P; Pramual, P

    2016-09-01

    An understanding of the genetic structure and diversity of vector species is crucial for effective control and management. In this study, mitochondrial DNA sequences were used to examine the genetic structure, diversity and demographic history of a black fly vector, Simulium nodosum Puri (Diptera: Simuliidae), in Thailand. A total of 145 sequences were obtained from 10 sampling locations collected across geographical ranges in the country. Low genetic diversity was found in populations of S. nodosum that could be explained by the recent population history of this species. Demographic history analysis revealed a signature of demographic expansion dating back to only 2600-5200 years ago. Recent population expansion in S. nodosum possibly followed an increase in agriculture that enabled its hosts', humans and domestic animals, densities to increase. Alternatively, the Thai populations could be a derivative of an older expansion event in the more northern populations. Mitochondrial DNA genealogy revealed no genetically divergent lineages, which agrees with the previous cytogenetic study. Genetic structure analyses found that only 27% of the pairwise comparisons were significantly different. The most likely explanation for the pattern of genetic structuring is the effect of genetic drift because of recent colonization. PMID:27245148

  17. China petrochemical expansion progressing

    SciTech Connect

    Not Available

    1991-08-05

    This paper reports on China's petrochemical expansion surge which is picking up speed. A worldscale petrochemical complex is emerging at Shanghai with an eye to expanding China's petrochemical exports, possibly through joint ventures with foreign companies, China Features reported. In other action, Beijing and Henan province have approved plans for a $1.2 billion chemical fibers complex at the proposed Luoyang refinery, China Daily reported.

  18. The Impact of Expansion

    PubMed Central

    Yaffe, Mark J.; Steinert, Yvonne

    1990-01-01

    Postgraduate training for family physicians has become increasingly centred on 2-year residency programs. The expansion of family medicine residency programs in Quebec raises challenges: to uphold program standards, to recruit and develop new teachers, to recognize and respect the needs of students, to balance program objectives with service requirements for house staff, and to adapt to change within family medicine centers and their affiliated hospitals. Imagesp2054-ap2057-a PMID:21233950

  19. Reconciling deep calibration and demographic history: bayesian inference of post glacial colonization patterns in Carcinus aestuarii (Nardo, 1847) and C. maenas (Linnaeus, 1758).

    PubMed

    Marino, Ilaria A M; Pujolar, Jose Martin; Zane, Lorenzo

    2011-01-01

    A precise inference of past demographic histories including dating of demographic events using bayesian methods can only be achieved with the use of appropriate molecular rates and evolutionary models. Using a set of 596 mitochondrial cytochrome c oxidase I (COI) sequences of two sister species of European green crabs of the genus Carcinus (C. maenas and C. aestuarii), our study shows how chronologies of past evolutionary events change significantly with the application of revised molecular rates that incorporate biogeographic events for calibration and appropriate demographic priors. A clear signal of demographic expansion was found for both species, dated between 10,000 and 20,000 years ago, which places the expansions events in a time frame following the Last Glacial Maximum (LGM). In the case of C. aestuarii, a population expansion was only inferred for the Adriatic-Ionian, suggestive of a colonization event following the flooding of the Adriatic Sea (18,000 years ago). For C. maenas, the demographic expansion inferred for the continental populations of West and North Europe might result from a northward recolonization from a southern refugium when the ice sheet retreated after the LGM. Collectively, our results highlight the importance of using adequate calibrations and demographic priors in order to avoid considerable overestimates of evolutionary time scales. PMID:22164307

  20. Reconciling Deep Calibration and Demographic History: Bayesian Inference of Post Glacial Colonization Patterns in Carcinus aestuarii (Nardo, 1847) and C. maenas (Linnaeus, 1758)

    PubMed Central

    Marino, Ilaria A. M.; Pujolar, Jose Martin; Zane, Lorenzo

    2011-01-01

    A precise inference of past demographic histories including dating of demographic events using Bayesian methods can only be achieved with the use of appropriate molecular rates and evolutionary models. Using a set of 596 mitochondrial cytochrome c oxidase I (COI) sequences of two sister species of European green crabs of the genus Carcinus (C. maenas and C. aestuarii), our study shows how chronologies of past evolutionary events change significantly with the application of revised molecular rates that incorporate biogeographic events for calibration and appropriate demographic priors. A clear signal of demographic expansion was found for both species, dated between 10,000 and 20,000 years ago, which places the expansions events in a time frame following the Last Glacial Maximum (LGM). In the case of C. aestuarii, a population expansion was only inferred for the Adriatic-Ionian, suggestive of a colonization event following the flooding of the Adriatic Sea (18,000 years ago). For C. maenas, the demographic expansion inferred for the continental populations of West and North Europe might result from a northward recolonization from a southern refugium when the ice sheet retreated after the LGM. Collectively, our results highlight the importance of using adequate calibrations and demographic priors in order to avoid considerable overestimates of evolutionary time scales. PMID:22164307

  1. Ultraprecise thermal expansion measurements of seven low expansion materials

    NASA Technical Reports Server (NTRS)

    Berthold, J. W., III; Jacobs, S. F.

    1976-01-01

    We summarize a large number of ultraprecise thermal expansion measurements made on seven different low expansivity materials. Expansion coefficients in the -150-300 C temperature range are shown for Owens-Illinois Cer-Vit C-101, Corning ULE 7971 (titanium silicate) and fused silica 7940, Heraeus-Schott Zerodur low-expansion material and Homosil fused silica, Universal Cyclops Invar LR-35, and Simonds Saw and Steel Super Invar.

  2. CENTRACT BOUNDARIES AND DEMOGRAPHIC DATABASE AND CVOVERAGE

    EPA Science Inventory

    This coverage contains Census Tract boundaries and associated demographic data. "Census tracts are small, relatively permanent statistical subdivisions of a county. Census tracts are delineated for all metropolitan areas (MAs) and other densely populated counties by local c...

  3. [Demographic processes and world population numbers].

    PubMed

    Donkov, K

    1986-01-01

    Recent global population trends are reviewed. The author notes the growing divergence in demographic trends between the developed and developing regions. These differences are analyzed in the light of Marxist population theory. (SUMMARY IN ENG AND RUS) PMID:12280530

  4. The demographic work of Sir William Wilde.

    PubMed

    Froggatt, P

    2016-05-01

    This paper argues that Sir William Wilde was indeed a pioneering demographer. It also describes the unveiling of the plaque commemorating Sir William Wilde at his home, 1, Merrion Square, Dublin on the 28 October 1971. PMID:27083459

  5. Characterizing food usage by demographic variables.

    PubMed

    Cronin, F J; Krebs-Smith, S M; Wyse, B W; Light, L

    1982-12-01

    On the basis of an analysis of three-day food records, food comsumption by major segments of the U.S. population was examined for 65 food groups and subgroups. This study indicates that demographic factors, particularly age, race, and region, can affect both the percentage of persons using certain foods and the mean frequency of their use. Both the similarities and the differences on these parameters are of interest when food usage is examined by demographic variables. PMID:7142608

  6. Studies on counterstreaming plasma expansion

    NASA Technical Reports Server (NTRS)

    Singh, N.; Thiemann, H.; Schunk, R. W.

    1986-01-01

    Recent studies on counterstreaming plasma expansions are summarized. The basic phenomenon of plasma expansion is reviewed, and results from one-dimensional simulations of counterstreaming plasma expansion are discussed. Results from simulations based on an electrostatic particle-in-cell code, in which the dynamics of both the electrons and ions are exactly followed, are discussed. The formation of electrostatic shocks is addressed. Finally, results are presented on the ionospheric plasma expansion along the geomagnetic flux tubes by solving the hydrodynamic equations.

  7. Magnetic expansion of cosmic plasmas

    NASA Technical Reports Server (NTRS)

    Yang, Wei-Hong

    1995-01-01

    Plasma expansion is common in many astrophysical phenomena. The understanding of the driving mechanism has usually been focused on the gas pressure that implies conversion of thermal energy into flow kinetic energy. However, 'cool' expansions have been indicated in stellar/solar winds and other expanding processes. Magnetic expansion may be the principal driving mechanism. Magnetic energy in the potential form can be converted into kinetic energy during global expansion of magnetized plasmas.

  8. MtDNA analysis of global populations support that major population expansions began before Neolithic Time

    NASA Astrophysics Data System (ADS)

    Zheng, Hong-Xiang; Yan, Shi; Qin, Zhen-Dong; Jin, Li

    2012-10-01

    Agriculture resulted in extensive population growths and human activities. However, whether major human expansions started after Neolithic Time still remained controversial. With the benefit of 1000 Genome Project, we were able to analyze a total of 910 samples from 11 populations in Africa, Europe and Americas. From these random samples, we identified the expansion lineages and reconstructed the historical demographic variations. In all the three continents, we found that most major lineage expansions (11 out of 15 star lineages in Africa, all autochthonous lineages in Europe and America) coalesced before the first appearance of agriculture. Furthermore, major population expansions were estimated after Last Glacial Maximum but before Neolithic Time, also corresponding to the result of major lineage expansions. Considering results in current and previous study, global mtDNA evidence showed that rising temperature after Last Glacial Maximum offered amiable environments and might be the most important factor for prehistorical human expansions.

  9. Expansion: A Plan for Success.

    ERIC Educational Resources Information Center

    Callahan, A.P.

    This report provides selling brokers' guidelines for the successful expansion of their operations outlining a basic method of preparing an expansion plan. Topic headings are: The Pitfalls of Expansion (The Language of Business, Timely Financial Reporting, Regulatory Agencies of Government, Preoccupation with the Facade of Business, A Business Is a…

  10. Expansion in condensates

    SciTech Connect

    Chakrabarti, J.; Sajjad Zahir, M.

    1985-03-01

    We show that the product of local current operators in quantum chromodynamics (QCD), when expanded in terms of condensates, such as psi-barpsi, G/sup a//sub munu/ G/sup a//sub munu/, psi-barGAMMA psipsi-barGAMMApsi, f/sub a/bcG/sup a//sub munu/G/sup b//sub nualpha/ x G/sup c//sub alphamu/, etc., yields a series in Planck's constant. This, however, provides no hint that the higher terms in such an expansion may be less significant.

  11. Load regulating expansion fixture

    DOEpatents

    Wagner, Lawrence M.; Strum, Michael J.

    1998-01-01

    A free standing self contained device for bonding ultra thin metallic films, such as 0.001 inch beryllium foils. The device will regulate to a predetermined load for solid state bonding when heated to a bonding temperature. The device includes a load regulating feature, whereby the expansion stresses generated for bonding are regulated and self adjusting. The load regulator comprises a pair of friction isolators with a plurality of annealed copper members located therebetween. The device, with the load regulator, will adjust to and maintain a stress level needed to successfully and economically complete a leak tight bond without damaging thin foils or other delicate components.

  12. Load regulating expansion fixture

    DOEpatents

    Wagner, L.M.; Strum, M.J.

    1998-12-15

    A free standing self contained device for bonding ultra thin metallic films, such as 0.001 inch beryllium foils is disclosed. The device will regulate to a predetermined load for solid state bonding when heated to a bonding temperature. The device includes a load regulating feature, whereby the expansion stresses generated for bonding are regulated and self adjusting. The load regulator comprises a pair of friction isolators with a plurality of annealed copper members located therebetween. The device, with the load regulator, will adjust to and maintain a stress level needed to successfully and economically complete a leak tight bond without damaging thin foils or other delicate components. 1 fig.

  13. Expansible quantum secret sharing network

    NASA Astrophysics Data System (ADS)

    Sun, Ying; Xu, Sheng-Wei; Chen, Xiu-Bo; Niu, Xin-Xin; Yang, Yi-Xian

    2013-08-01

    In the practical applications, member expansion is a usual demand during the development of a secret sharing network. However, there are few consideration and discussion on network expansibility in the existing quantum secret sharing schemes. We propose an expansible quantum secret sharing scheme with relatively simple and economical quantum resources and show how to split and reconstruct the quantum secret among an expansible user group in our scheme. Its trait, no requirement of any agent's assistant during the process of member expansion, can help to prevent potential menaces of insider cheating. We also give a discussion on the security of this scheme from three aspects.

  14. Immediate versus chronic tissue expansion.

    PubMed

    Machida, B K; Liu-Shindo, M; Sasaki, G H; Rice, D H; Chandrasoma, P

    1991-03-01

    A quantitative comparison of the effects on tissues is performed between chronic tissue expansion, intraoperative expansion, and load cycling in a guinea pig model. Intra-operative expansion, which was developed by Sasaki as a method of immediate tissue expansion for small- to medium-sized defects, and load cycling, which was described by Gibson as a method using intraoperative pull, are compared with chronic tissue expansion on the basis of the following four parameters: amount of skin produced, flap viability, intraoperative tissue pressures, and histological changes. The chronically expanded group, which included booster and nonbooster expansions, produced a 137% increase in surface area, or a 52% increase in flap arc length, whereas intraoperative expansion resulted in a 31% increase in surface area, or a 15% increase in flap arc length. The load-cycled group, however, resulted in an almost negligible amount of skin increase. All three techniques exhibit immediate postexpansion stretchback. Flap viability is not impaired by any of the three techniques, in spite of the elevated pressures observed during expansion. Therefore, intraoperative expansion is effective primarily for limited expansion of small defects, whereas chronic tissue expansion still provides the greatest amount of skin increase when compared with other techniques. PMID:2029132

  15. Identifying image preferences based on demographic attributes

    NASA Astrophysics Data System (ADS)

    Fedorovskaya, Elena A.; Lawrence, Daniel R.

    2014-02-01

    The intent of this study is to determine what sorts of images are considered more interesting by which demographic groups. Specifically, we attempt to identify images whose interestingness ratings are influenced by the demographic attribute of the viewer's gender. To that end, we use the data from an experiment where 18 participants (9 women and 9 men) rated several hundred images based on "visual interest" or preferences in viewing images. The images were selected to represent the consumer "photo-space" - typical categories of subject matter found in consumer photo collections. They were annotated using perceptual and semantic descriptors. In analyzing the image interestingness ratings, we apply a multivariate procedure known as forced classification, a feature of dual scaling, a discrete analogue of principal components analysis (similar to correspondence analysis). This particular analysis of ratings (i.e., ordered-choice or Likert) data enables the investigator to emphasize the effect of a specific item or collection of items. We focus on the influence of the demographic item of gender on the analysis, so that the solutions are essentially confined to subspaces spanned by the emphasized item. Using this technique, we can know definitively which images' ratings have been influenced by the demographic item of choice. Subsequently, images can be evaluated and linked, on one hand, to their perceptual and semantic descriptors, and, on the other hand, to the preferences associated with viewers' demographic attributes.

  16. [Thoughts on demographic optimization in contemporary Poland].

    PubMed

    Oledzki, M

    1980-01-01

    This article presents the viewpoint of the Polish school of social policy of the Institute of Social Economy concerning the problem of optimization of demographic structures and processes in contemporary Poland. This school was created under the leadership of the outstanding sociologist Ludwik Krzywicki (1859-1941). The reasoning concerns, first of all, the scientific premises of the choice of criteria of demographic optimization examined and then there is a critical assessment of modern simplified approaches to the definition of optimum population. It also shows actual possibilities of demographic optimization and the complexity of analytical categories of socioeconomic processes which determine the development of the population in specific time and space. In conclusion, the theory of demographic optimization is regarded as a task too ambitious and perhaps even utopian in view of the assumptions needed for its satisfactory realization. This conclusion confirms the thesis contained in the handbook of demography by J.Z. Holzer published in 1970. The author considers, however, that the search for a theory of demographic optimization is still a task which mobilizes social sciences to an integration centered on demography and social policy. (author's) PMID:12338379

  17. [The beginning of the Cuban demographic revolution].

    PubMed

    Hernandez Castellon, R

    1981-01-01

    The characteristics of the Cuban demographic revolution associated with the main economic, political, and social changes in the country are analyzed. The authors begin with a brief historical outline of the political-economic situation in the country in the middle of the 19th century. There is emphasis on the dependency of the Cuban economy and its monoproducer nature (with sugar being the major export). This was due to the Spanish colonization and to the subsequent American neocolonization. The discovery of the cause for yellow fever by a Cuban physician and the sanitation campaign conducted by the Americans contributed to a diminishing of mortality. A great migratory flow occurred due to the price of sugar in the world market. This must have influenced Cuban demographic patterns which are a major factor linked to the demographic revolution. The influence on proliferation of urbanization and educational trends is emphasized. The low participation in economic activities of women during the early part of the century did affect fertility levels. The trends in mortality throughout the period 1907-43 are pointed out. It was found that 1 major aspect which had a bearing on Cuban demographic patterns was the 2 large migratory flows. An analysis of growth rates in the population--which also confirms the demographic changes in Cuba--is presented. It is concluded that the 4th decade of this century witnessed Cuba's entry in a new stage of the demographic revolution, a stage in which decreased fertility and mortality go together to create a new period. (author's) PMID:12279297

  18. [Demographic and economic development in contemporary Mexico].

    PubMed

    Alba, F

    1989-01-01

    This paper briefly reviews the main features of the recent Mexican experience in demographic and economic development matters. It assesses the development pattern that prevailed between 1940 and 1970 and the ways and policies that were instrumental in accommodating the rapid population growth of the period. The author considers that by 1970 the relatively acceptable demo-economic system in place since 1940 entered a period of emerging tensions, and examines the responses to those difficulties, among them the change in population policy. It closes with a brief review of the tasks ahead considering future demographic and economic tendencies in Mexico. PMID:2740942

  19. Cryogenic expansion machine

    DOEpatents

    Pallaver, Carl B.; Morgan, Michael W.

    1978-01-01

    A cryogenic expansion engine includes intake and exhaust poppet valves each controlled by a cam having adjustable dwell, the valve seats for the valves being threaded inserts in the valve block. Each cam includes a cam base and a ring-shaped cam insert disposed at an exterior corner of the cam base, the cam base and cam insert being generally circular but including an enlarged cam dwell, the circumferential configuration of the cam base and cam dwell being identical, the cam insert being rotatable with respect to the cam base. GI CONTRACTUAL ORIGIN OF THE INVENTION The invention described herein was made in the course of, or under, a contract with the UNITED STATES ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATION.

  20. Range-wide selection of catchments for Pacific salmon conservation.

    PubMed

    Pinsky, Malin L; Springmeyer, Dane B; Goslin, Matthew N; Augerot, Xanthippe

    2009-06-01

    Freshwater ecosystems are declining in quality globally, but a lack of data inhibits identification of areas valuable for conservation across national borders. We developed a biological measure of conservation value for six species of Pacific salmon (Oncorhynchus spp.) in catchments of the northern Pacific across Canada, China, Japan, Russia, and the United States. We based the measure on abundance and life-history richness and a model-based method that filled data gaps. Catchments with high conservation value ranged from California to northern Russia and included catchments in regions that are strongly affected by human development (e.g., Puget Sound). Catchments with high conservation value were less affected by agriculture and dams than other catchments, although only 1% were within biodiversity reserves. Our set of high-value areas was largely insensitive to simulated error, although classification remained uncertain for 3% of catchments. Although salmon face many threats, we propose they will be most likely to exhibit resilience into the future if a complementary mosaic of conservation strategies can be proactively adopted in catchments with healthy salmon populations. Our analysis provides an initial map of where these catchments are likely to be located. PMID:19220368

  1. Shrub encroachment control by browsing: Targeting the right demographic process

    NASA Astrophysics Data System (ADS)

    da Silveira Pontes, Laíse; Magda, Danièle; Jarry, Marc; Gleizes, Benoît; Agreil, Cyril

    2012-11-01

    Exploring key demographic parameters for establishment and growth of shrub populations enables us to identify the life stages or plant organs that browsers need to consume to effectively influence shrub population dynamics. However, there is a lack of concrete knowledge on how browsing can efficiently meet this goal. We therefore tested the impact of different levels of browsing intensity on a key demographic parameter (survival of juveniles) of a major colonizing shrub species (broom, Cytisus scoparius) in order to control population growth, and designed a browsing management strategy focused on this target stage. Three browsing intensities, representing pertinent management practices, were simulated on juveniles (2 years old) in a broom population. Juvenile broom plants were either left untouched (control treatment; n = 126) or had 50% or 90% of their total edible stem biomass removed for "light-intensity browsing" (n = 127) and "high-intensity browsing" (n = 77) treatments, respectively. Survival and fecundity data were collected over 6 years. Standard matrix modeling was used to analyze the impact of browsing on changes in population growth rate (λ), and the results were 6.34 (control), 2.26 (light browsing) and 0.85 (heavy browsing). Therefore, the natural expansion of broom populations may be slowed by light browsing or even reversed by heavy browsing (λ < 1). This multi-year survey confirms that focusing browsing on juveniles is an efficient strategy for controlling broom dominance. Shrub control strategies should therefore target early-growth-stage populations and repeat the browsing strategy at the same intensity over several years to achieve cumulative effects.

  2. Heterogeneity of microsatellite mutations within and between loci, and implications for human demographic histories.

    PubMed Central

    Di Rienzo, A; Donnelly, P; Toomajian, C; Sisk, B; Hill, A; Petzl-Erler, M L; Haines, G K; Barch, D H

    1998-01-01

    Microsatellites have been widely used to reconstruct human evolution. However, the efficient use of these markers relies on information regarding the process producing the observed variation. Here, we present a novel approach to the locus-by-locus characterization of this process. By analyzing somatic mutations in cancer patients, we estimated the distributions of mutation size for each of 20 loci. The same loci were then typed in three ethnically diverse population samples. The generalized stepwise mutation model was used to test the predicted relationship between population and mutation parameters under two demographic scenarios: constant population size and rapid expansion. The agreement between the observed and expected relationship between population and mutation parameters, even when the latter are estimated in cancer patients, confirms that somatic mutations may be useful for investigating the process underlying population variation. Estimated distributions of mutation size differ substantially amongst loci, and mutations of more than one repeat unit are common. A new statistic, the normalized population variance, is introduced for multilocus estimation of demographic parameters, and for testing demographic scenarios. The observed population variation is not consistent with a constant population size. Time estimates of the putative population expansion are in agreement with those obtained by other methods. PMID:9539441

  3. The demographic dynamics of small island societies.

    PubMed

    Cruz, M; D'ayala, P G; Marcus, E; Mcelroy, J L; Rossi, O

    1987-01-01

    Small islands and microstates have demonstrated a unique demographic pattern, including cycles of swift population increases or decreases well beyond natural birth and death rate balances. These demographic fluctuations have been produced largely by rises or declines in market opportunities. The process of taking advantage of favorable opportunities is always followed by a specialization in the given activity, without regard to environmental protection issues or a longterm strategy for economic development and resource diversification. The population growth phase is associated with increasing fragility of the economic base, whether because of the external dangers of overspecialization or induced internal dysfunctions such as disease and resource depletion. Eventually complete collapse results, causing chronic outmigration or even depopulation. Case histories of maritime basins in the Mediterranean, Caribbean, and Pacific show that the demographic structure of small islands has been particularly sensitive to changing economic opportunities, the vagaries of market forces, and cataclysmic natural events. Experience in these areas suggests that balanced economic development of small islands should be based on diversification of activities, thus ensuring a relatively stable pattern of growth, sound environmental management, and control of dangerous demographic fluctuations. Special attention should be given to the development of broad-based research and cooperation to integrate specific island opportunities within a regional network. PMID:12281361

  4. Demographic Projections and Educational Policy Issues.

    ERIC Educational Resources Information Center

    Little, Dennis L.

    Significant changes in various demographic patterns include a declining birth rate, regional shifts from the "Snow Belt" to the "Sun Belt" as well as a return to rural America, an increase in female labor force participation, a general change in family structure ("kids with kids," single parent families, unmarried couples, etc.), and changes in…

  5. On modern demographic transition in China.

    PubMed

    1991-12-01

    The theory of demographic transition traditionally indicates 3 historical stages. The limitations of the theory are: 1)studies are confined to phenomenal descriptions which means that China is exempt, 2) it focuses too much on productive forces and ignores the factor of the relation between production and other non-economic factors. There is more to transition theories than birth rate, death rate of natural increase. In 1971 China began the process of modern demographic transition with a death rate of 0.7% and a drop in the birth rate. In 1976 China began the 2nd stage where birth rates doubled which made China a unique case because it fell outside the conventional model. The primary factor for this was the change in the fertility rate. The effects of population policy on fertility will be less if economic development and cultural development do not keep pace. The fact that rural people were reluctant to accept the population policy was a strong factor. The 2nd rise is attributed to the "flexible minor policies". This 2nd rise will be a significant factor in future population development. The key to modern demographic transition in China is to lower the birth rate by: 1) developing economic policies that will increase the quality of social and economic backgrounds, 2) the interference of the policy in demographic transition should follow the medium principle, 3) communication and education should be increased to help people set up the value of less births, better births. PMID:12284673

  6. Selected Statistics: Demographic, Social, Economic, Education.

    ERIC Educational Resources Information Center

    Office of Education (DHEW), Chicago, IL. Regional Office 5.

    The publication, intended for persons involved in educational activities, provides selected data on demographic, social, economic, and educational characteristics of Region V, United States Department of Education. Region V comprises Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin. The majority of the data was drawn from the 1976…

  7. 5 CFR 841.404 - Demographic factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 2 2012-01-01 2012-01-01 false Demographic factors. 841.404 Section 841.404 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-GENERAL ADMINISTRATION Government Costs § 841.404...

  8. 5 CFR 841.404 - Demographic factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 2 2014-01-01 2014-01-01 false Demographic factors. 841.404 Section 841.404 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-GENERAL ADMINISTRATION Government Costs § 841.404...

  9. 5 CFR 841.404 - Demographic factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Demographic factors. 841.404 Section 841.404 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-GENERAL ADMINISTRATION Government Costs § 841.404...

  10. Economic and Demographic Predictors of Inclusive Education

    ERIC Educational Resources Information Center

    Cosier, Meghan E.; Causton-Theoharis, Julie

    2011-01-01

    This study investigated economic and demographic predictors of levels of inclusion of students with disabilities in 129 school districts. Multiple regression analysis was utilized to address the following research questions: (a) Is there a relationship between economic factors and percentage of highly included students with disabilities in general…

  11. Changing demographics and shrinking engineering enrollments

    SciTech Connect

    Vetter, B.M. )

    1992-03-01

    This paper reports that changing U.S. population demographics, poor academic preparation, and a decreasing interest in engineering among college student indicate possible shortages ahead, particularly among chemical and petroleum engineers. If we are to ensure an adequate future supply for the U.S., the engineering talent pool must be enlarged to include women and minority men.

  12. 5 CFR 841.404 - Demographic factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Demographic factors. 841.404 Section 841.404 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-GENERAL ADMINISTRATION Government Costs § 841.404...

  13. Psychological and Demographic Correlates of Career Patterns

    ERIC Educational Resources Information Center

    Reitzle, Matthias; Korner, Astrid; Vondracek, Fred W.

    2009-01-01

    Recent years have witnessed a growing diversity of career patterns, resulting from the relative decline of stable employment. In the present study of 1368 employed and self-employed German adults career pattern diversity was assessed using nine pictograms. The goal was to identify psychological and demographic correlates of these patterns and to…

  14. Demographic and Lifestyle Variables Associated with Obesity

    ERIC Educational Resources Information Center

    Worthy, Sheri L.; Lokken, Kristine; Pilcher, Kenneth; Boeka, Abbe

    2010-01-01

    Objective: Overweight and obesity rates are associated with chronic diseases and higher rates of disability and continue to rise in the United States and worldwide. The purpose of this study was to build on past research and further investigate demographic and lifestyle variables associated with increased body mass index (BMI: kg/m[squared]).…

  15. A Model for External Demographic Analysis.

    ERIC Educational Resources Information Center

    Hall, Barbara Ann

    A data-collection model is presented for the gathering of timely information on population demographic characteristics, as well as economic, educational, environmental, and social trends. First, the paper discusses the importance of anticipating internal and external changes and establishing priorities for resource allocation in the design of a…

  16. Demographic Group Differences in Adolescents' Time Attitudes

    ERIC Educational Resources Information Center

    Andretta, James R.; Worrell, Frank C.; Mello, Zena R.; Dixson, Dante D.; Baik, Sharon H.

    2013-01-01

    In the present study, we examined demographic differences in time attitudes in a sample of 293 adolescents. Time attitudes were measured using the Adolescent Time Attitude Scale (Mello & Worrell, 2007; Worrell, Mello, & Buhl, 2011), which assesses positive and negative attitudes toward the past, the present, and the future. Generally, African…

  17. Demographic development in ASEAN: a comparative overview.

    PubMed

    Herrin, A N; Pardoko, H; Lim, L L; Hongladorom, C

    1981-01-01

    A comparative overview of recent demographic developments in the ASEAN (Association of Southeast Asian Nations) region is presented. Countries discussed include Indonesia, Malaysia, the Philippines, Singapore, and Thailand. Separate consideration is given to mortality; fertility; and migration, spatial distribution, and employment. A final section is concerned with emerging issues and directions for population policy. PMID:12178278

  18. Earliest Recollections of Childhood: A Demographic Analysis.

    ERIC Educational Resources Information Center

    Mullen, Mary K.

    1994-01-01

    Four questionnaires examined the association of demographic factors with recollection for 768 adults. Found that the age of earliest memory increased across birth order, was slightly earlier for females than for males, and was earlier for Caucasians than for Asians. (Author/BC)

  19. Using Demographic Studies to Project School Enrollments.

    ERIC Educational Resources Information Center

    Grip, Richard S.

    2002-01-01

    Describes how to use demographic studies to project school enrollments. Includes collecting historical enrollment data, contacting the state department of health and vital statistics, selecting an enrollment-projection method, meeting with local planning and construction department officials, determining the age of the community, and performing…

  20. [Demographic transition at the epoch of industrialization].

    PubMed

    Billig, W

    1984-01-01

    The relationship between the early stages of industrialization and population factors in the United Kingdom, France, and the United States is analyzed from a Marxist perspective. The author attempts to associate successive phases of industrialization with phases of the demographic transition. He concludes that no comprehensive general theory concerning this relationship has been established. (summary in ENG, RUS) PMID:12266382

  1. Understanding China's Demographic Dividends and Labor Issue

    ERIC Educational Resources Information Center

    Peng, Xizhe

    2013-01-01

    One of the major concerns about the one-child policy is its negative impact on the current and future labor force in China. People have talked about the Lewis Turning Point and the end of demographic dividends. Some of these arguments, however, can be misleading. The working-age population (ages 15 to 59) can be treated as the potential labor…

  2. A Demographic Profile of Cuban Americans.

    ERIC Educational Resources Information Center

    Boswell, Thomas D.

    This study offers a demographic profile of the U.S. Cuban population, using data from the decennial census and current population surveys. Part one estimates the number of Cuban Americans and describes their geographic distribution nationwide. Part two compares the socioeconomic characteristics (age, gender, educational attainment, income,…

  3. Prescription Drug Expenditures and Population Demographics

    PubMed Central

    Morgan, Steven G

    2006-01-01

    Objective To provide detailed demographic profiles of prescription drug utilization and expenditures in order to isolate the impact of demographic change from other factors that affect drug expenditure trends. Data Sources/Study Setting Demographic information and drug utilization data were extracted for virtually the entire British Columbia (BC) population of 1996 and 2002. All residents had public medical and hospital insurance; however their drug coverage resembled the mix of private and public insurance in the United States. Study Design A series of research variables were constructed to illustrate profiles of drug expenditures and drug utilization across 96 age/sex strata. Data Collection/Extraction Methods Drug use and expenditure information was extracted from the BC PharmaNet, a computer network connecting all pharmacies in the province. Principal Findings Per capita drug expenditures increased at an average annual rate of 10.8 percent between 1996 and 2002. Population aging explained 1.0 points of this annual rate of expenditure growth; the balance was attributable to rising age/sex-specific drug expenditures. Conclusions Relatively little of the observed increase in drug expenditures in BC could be attributed to demographic change. Most of the expenditure increase stemmed from the age/sex-specific quantity and type of drugs purchased. The sustainability of drug spending therefore depends not on outside forces but on decisions made by policy makers, prescribers, and patients. PMID:16584456

  4. State Differences: The Key to Demographics.

    ERIC Educational Resources Information Center

    Hodgkinson, Harold

    1999-01-01

    This companion piece to a 1997 article examines United States demographic trends, such as diversity by age, "race" and U.S. Census racial classifications, wealth, transiency, suburbanization and sprawl, and immigration, focusing on differences among states and metro regions. Nothing, including achievement scores, social services, and financial…

  5. Life Potential as a Basic Demographic Indicator

    ERIC Educational Resources Information Center

    Goerlich, Francisco J.; Soler, Angel

    2013-01-01

    This paper proposes an indicator that integrates life expectancy with the demographic structure of the population for a given society. By doing this, we have a simple indicator of mortality and aging combined, which could be very useful for developed societies. As is widely known, life expectancy at birth is independent of the demographic…

  6. The Demographics of Corporal Punishment in Texas

    ERIC Educational Resources Information Center

    Phillips, Stephanie

    2012-01-01

    This dissertation examined the student discipline policies of 1,025 Texas school districts, as well as data from the Texas Education Agency's Academic Excellence Indicator System in order to identify demographic patterns regarding corporal punishment policies in Texas schools. The study also studied the relationship between a district's…

  7. Immigration: The Demographic and Economic Facts.

    ERIC Educational Resources Information Center

    Simon, Julian L.

    This report contains economic and demographic facts related to immigration, but it does not advocate any position or ideology nor make any judgments about whether immigrants should receive government services. When possible, data are presented as graphs. A review of the facts makes it apparent that the rate of U.S. immigration in the 1990s is…

  8. Demographic Change and Local School District Organization.

    ERIC Educational Resources Information Center

    Hanson, Ellis G.

    This paper summarizes a Great Plains School District Organization Project publication, People, Places, Perspectives: the Great Plains States, which was concerned with the demographic characteristics of the Midwest and their implications for educational planners. The author suggests that the challenges facing educational planners in the Midwest, as…

  9. Burial Ground Expansion Hydrogeologic Characterization

    SciTech Connect

    Gaughan , T.F.

    1999-02-26

    Sirrine Environmental Consultants provided technical oversight of the installation of eighteen groundwater monitoring wells and six exploratory borings around the location of the Burial Ground Expansion.

  10. Demographic influences on the behavior of chimpanzees.

    PubMed

    Mitani, John C

    2006-01-01

    Recent research has revealed substantial diversity in the behavior of wild chimpanzees. Understanding the sources of this variation has become a central focus of investigation. While genetic, ecological, and cultural factors are often invoked to explain behavioral variation in chimpanzees, the demographic context is sometimes overlooked as a contributing factor. Observations of chimpanzees at Ngogo, Kibale National Park, Uganda, reveal that the size and structure of the unit group or community can both facilitate and constrain the manifestation of behavior. With approximately 150 individuals, the Ngogo community is much larger than others that have been studied in the wild. We have taken advantage of the unusual demographic structure of this community to document new and intriguing patterns of chimpanzee behavior with respect to hunting, territoriality, and male social relationships. Chimpanzees at Ngogo hunt often and with a considerable degree of success. In addition, male chimpanzees there frequently patrol the boundary of their territory and engage in repeated bouts of lethal intergroup aggression. By forming two distinct subgroups, male chimpanzees at Ngogo also develop social bonds above the level of dyadic pairs. While the sheer number of chimpanzees contributes to differences in hunting, patrolling, mating, and subgrouping at Ngogo, the demographic situation may also constrain behavioral interactions. At Ngogo, male chimpanzees who are closely related genetically through the maternal line do not appear to affiliate or cooperate with each other. Demographic constraints may be responsible for this finding. In this paper, I use these examples to illustrate how the demographic context affects the possible range of behavioral options open to individuals and ultimately contributes to the explanation of behavioral diversity in chimpanzees. PMID:16283424

  11. Singularity Expansion Method

    NASA Astrophysics Data System (ADS)

    Riggs, Lloyd Stephen

    In this work the transient currents induced on an arbitrary system of thin linear scatterers by an electromagnetic plane wave are solved by using an electric field integral equation (EFIE) formulation. The transient analysis is carried out using the singularity expansion method (SEM). The general analysis developed here is useful for assessing the vulnerability of military aircraft to a nuclear generated electromagnetic pulse (EMP). It is also useful as a modal synthesis tool in the analysis and design of frequency selective surfaces (FSS). SEM parameters for a variety of thin cylindrical geometries have been computed. Specifically, SEM poles, modes, coupling coefficients, and transient currents are given for the two and three element planar array. Poles and modes for planar arrays with a larger number (as many as eight) of identical equally spaced elements are also considered. SEM pole-mode results are given for identical parallel elements with ends located at the vertices of a regular N-agon. Pole-mode patterns are found for symmetric (and slightly perturbed) single junction N-arm elements and for the five junction Jerusalem cross. The Jerusalem cross element has been used extensively in FSS.

  12. Length distributions of identity by descent reveal fine-scale demographic history.

    PubMed

    Palamara, Pier Francesco; Lencz, Todd; Darvasi, Ariel; Pe'er, Itsik

    2012-11-01

    Data-driven studies of identity by descent (IBD) were recently enabled by high-resolution genomic data from large cohorts and scalable algorithms for IBD detection. Yet, haplotype sharing currently represents an underutilized source of information for population-genetics research. We present analytical results on the relationship between haplotype sharing across purportedly unrelated individuals and a population's demographic history. We express the distribution of IBD sharing across pairs of individuals for segments of arbitrary length as a function of the population's demography, and we derive an inference procedure to reconstruct such demographic history. The accuracy of the proposed reconstruction methodology was extensively tested on simulated data. We applied this methodology to two densely typed data sets: 500 Ashkenazi Jewish (AJ) individuals and 56 Kenyan Maasai (MKK) individuals (HapMap 3 data set). Reconstructing the demographic history of the AJ cohort, we recovered two subsequent population expansions, separated by a severe founder event, consistent with previous analysis of lower-throughput genetic data and historical accounts of AJ history. In the MKK cohort, high levels of cryptic relatedness were detected. The spectrum of IBD sharing is consistent with a demographic model in which several small-sized demes intermix through high migration rates and result in enrichment of shared long-range haplotypes. This scenario of historically structured demographies might explain the unexpected abundance of runs of homozygosity within several populations. PMID:23103233

  13. Independent Demographic Responses to Climate Change among Temperate and Tropical Milksnakes (Colubridae: Genus Lampropeltis)

    PubMed Central

    Ruane, Sara; Torres-Carvajal, Omar; Burbrink, Frank T.

    2015-01-01

    The effects of Late Quaternary climate change have been examined for many temperate New World taxa, but the impact of Pleistocene glacial cycles on Neotropical taxa is less well understood, specifically with respect to changes in population demography. Here, we examine historical demographic trends for six species of milksnake with representatives in both the temperate and tropical Americas to determine if species share responses to climate change as a taxon or by area (i.e., temperate versus tropical environments). Using a multilocus dataset, we test for the demographic signature of population expansion and decline using non-genealogical summary statistics, as well as coalescent-based methods. In addition, we determine whether range sizes are correlated with effective population sizes for milksnakes. Results indicate that there are no identifiable trends with respect to demographic response based on location, and that species responded to changing climates independently, with tropical taxa showing greater instability. There is also no correlation between range size and effective population size, with the largest population size belonging to the species with the smallest geographic distribution. Our study highlights the importance of not generalizing the demographic histories of taxa by region and further illustrates that the New World tropics may not have been a stable refuge during the Pleistocene. PMID:26083467

  14. Isotropic Negative Thermal Expansion Metamaterials.

    PubMed

    Wu, Lingling; Li, Bo; Zhou, Ji

    2016-07-13

    Negative thermal expansion materials are important and desirable in science and engineering applications. However, natural materials with isotropic negative thermal expansion are rare and usually unsatisfied in performance. Here, we propose a novel method to achieve two- and three-dimensional negative thermal expansion metamaterials via antichiral structures. The two-dimensional metamaterial is constructed with unit cells that combine bimaterial strips and antichiral structures, while the three-dimensional metamaterial is fabricated by a multimaterial 3D printing process. Both experimental and simulation results display isotropic negative thermal expansion property of the samples. The effective coefficient of negative thermal expansion of the proposed models is demonstrated to be dependent on the difference between the thermal expansion coefficient of the component materials, as well as on the circular node radius and the ligament length in the antichiral structures. The measured value of the linear negative thermal expansion coefficient of the three-dimensional sample is among the largest achieved in experiments to date. Our findings provide an easy and practical approach to obtaining materials with tunable negative thermal expansion on any scale. PMID:27333052

  15. Simulation of Demographic Change in Palestinian Territories

    NASA Astrophysics Data System (ADS)

    Sumour, M. A.; El-Astal, A. H.; Shabat, M. M.; Radwan, M. A.

    Mortality, birth rates and retirement play a major role in demographic changes. In most cases, mortality rates decreased in the past century without noticeable decrease in fertility rates, leading to a significant increase in population growth. In many poor countries like Palestinian Territories the number of births has fallen and the life expectancy increased. In this paper we concentrate on measuring, analyzing and extrapolating the age structure in Palestine a few decades ago into the future. A Fortran program has been designed and used for the simulation and analysis of our statistical data. This study of demographic change in Palestine has shown that Palestinians will have in future problems as the strongest age cohorts are the above-60-year olds. We therefore recommend the increase of both the retirement age and female employment.

  16. New Approaches to Demographic Data Collection

    PubMed Central

    Treiman, Donald J.; Lu, Yao; Qi, Yaqiang

    2013-01-01

    As population scientists have expanded the range of topics they study, increasingly considering the interrelationship between population phenomena and social, economic, and health conditions, they have expanded the kinds of data collected and have brought to bear new data collection techniques and procedures, often borrowed from other fields. These new approaches to demographic data collection are the concern of this essay. We consider three main topics: new developments in sampling procedures; new developments in fieldwork procedures; and new developments in the kind of information collected in demographic and social surveys. We conclude with some comments on data sharing in the social research community and a list of major Chinese surveys publicly available to researchers. Where possible we illustrate our points with Chinese examples. PMID:23844330

  17. Soft Selective Sweeps in Complex Demographic Scenarios

    PubMed Central

    Wilson, Benjamin A.; Petrov, Dmitri A.; Messer, Philipp W.

    2014-01-01

    Adaptation from de novo mutation can produce so-called soft selective sweeps, where adaptive alleles of independent mutational origin sweep through the population at the same time. Population genetic theory predicts that such soft sweeps should be likely if the product of the population size and the mutation rate toward the adaptive allele is sufficiently large, such that multiple adaptive mutations can establish before one has reached fixation; however, it remains unclear how demographic processes affect the probability of observing soft sweeps. Here we extend the theory of soft selective sweeps to realistic demographic scenarios that allow for changes in population size over time. We first show that population bottlenecks can lead to the removal of all but one adaptive lineage from an initially soft selective sweep. The parameter regime under which such “hardening” of soft selective sweeps is likely is determined by a simple heuristic condition. We further develop a generalized analytical framework, based on an extension of the coalescent process, for calculating the probability of soft sweeps under arbitrary demographic scenarios. Two important limits emerge within this analytical framework: In the limit where population-size fluctuations are fast compared to the duration of the sweep, the likelihood of soft sweeps is determined by the harmonic mean of the variance effective population size estimated over the duration of the sweep; in the opposing slow fluctuation limit, the likelihood of soft sweeps is determined by the instantaneous variance effective population size at the onset of the sweep. We show that as a consequence of this finding the probability of observing soft sweeps becomes a function of the strength of selection. Specifically, in species with sharply fluctuating population size, strong selection is more likely to produce soft sweeps than weak selection. Our results highlight the importance of accurate demographic estimates over short

  18. The Demographic Transition: Causes and Consequences

    PubMed Central

    Galor, Oded

    2013-01-01

    This paper develops the theoretical foundations and the testable implications of the various mechanisms that have been proposed as possible triggers for the demographic transition. Moreover, it examines the empirical validity of each of the theories and their significance for the understanding of the transition from stagnation to growth. The analysis suggests that the rise in the demand for human capital in the process of development was the main trigger for the decline in fertility and the transition to modern growth PMID:25089157

  19. [Demographic developments in 1996: increased immigration].

    PubMed

    De Beer, J; Prins, C J

    1997-03-01

    "The major demographic event [in the Netherlands] in 1996 has been the increase in immigration from 96 thousand to 109 thousand. Both the immigration from countries such as Turkey and Morocco and the immigration from the countries of the European Union increased. The number of asylum seekers, however, decreased. The numbers of births, deaths and emigrants hardly changed in 1996. In spite of the increase in immigration, population growth was only slightly higher than in the preceding year." (EXCERPT) PMID:12321087

  20. The Demographic Transition: Causes and Consequences.

    PubMed

    Galor, Oded

    2012-01-01

    This paper develops the theoretical foundations and the testable implications of the various mechanisms that have been proposed as possible triggers for the demographic transition. Moreover, it examines the empirical validity of each of the theories and their significance for the understanding of the transition from stagnation to growth. The analysis suggests that the rise in the demand for human capital in the process of development was the main trigger for the decline in fertility and the transition to modern growth. PMID:25089157

  1. Geographical barriers and climate influence demographic history in narrowleaf cottonwoods

    PubMed Central

    Evans, L M; Allan, G J; DiFazio, S P; Slavov, G T; Wilder, J A; Floate, K D; Rood, S B; Whitham, T G

    2015-01-01

    Studies of genetic variation can clarify the role of geography and spatio-temporal variation of climate in shaping demography, particularly in temperate zone tree species with large latitudinal ranges. Here, we examined genetic variation in narrowleaf cottonwood, Populus angustifolia, a dominant riparian tree. Using multi-locus surveys of polymorphism in 363 individuals across the species' 1800 km latitudinal range, we found that, first, P. angustifolia has stronger neutral genetic structure than many forest trees (simple sequence repeat (SSR) FST=0.21), with major genetic groups corresponding to large apparent geographical barriers to gene flow. Second, using SSRs and putatively neutral sequenced loci, coalescent simulations indicated that populations diverged before the last glacial maximum (LGM), suggesting the presence of population structure before the LGM. Third, the LGM and subsequent warming appear to have had different influences on each of these distinct populations, with effective population size reduction in the southern extent of the range but major expansion in the north. These results are consistent with the hypothesis that climate and geographic barriers have jointly affected the demographic history of P. angustifolia, and point the importance of both factors as being instrumental in shaping genetic variation and structure in widespread forest trees. PMID:25585921

  2. Phylogeography and demographic history of the neotropical otter (Lontra longicaudis).

    PubMed

    Trinca, Cristine S; de Thoisy, Benoit; Rosas, Fernando C W; Waldemarin, Helen F; Koepfli, Klaus-Peter; Vianna, Juliana A; Eizirik, Eduardo

    2012-07-01

    The Neotropical otter (Lontra longicaudis) is a medium-sized semiaquatic carnivore with a broad distribution in the Neotropical region. Despite being apparently common in many areas, it is one of the least known otters, and genetic studies on this species are scarce. Here, we have investigated its genetic diversity, population structure, and demographic history across a large portion of its geographic range by analyzing 1471 base pairs (bp) of mitochondrial DNA from 52 individuals. Our results indicate that L. longicaudis presents high levels of genetic diversity and a consistent phylogeographic pattern, suggesting the existence of at least 4 distinct evolutionary lineages in South America. The observed phylogeographic partitions are partially congruent with the subspecies classification previously proposed for this species. Coalescence-based analyses indicate that Neotropical otter mitochondrial DNA lineages have shared a rather recent common ancestor, approximately 0.5 Ma, and have subsequently diversified into the observed phylogroups. A consistent scenario of recent population expansion was identified in Eastern South America based on several complementary analyses of historical demography. The results obtained here provide novel insights on the evolutionary history of this largely unknown Neotropical mustelid and should be useful to design conservation and management policies on behalf of this species and its habitats. PMID:22589556

  3. Geographical barriers and climate influence demographic history in narrowleaf cottonwoods.

    PubMed

    Evans, L M; Allan, G J; DiFazio, S P; Slavov, G T; Wilder, J A; Floate, K D; Rood, S B; Whitham, T G

    2015-04-01

    Studies of genetic variation can clarify the role of geography and spatio-temporal variation of climate in shaping demography, particularly in temperate zone tree species with large latitudinal ranges. Here, we examined genetic variation in narrowleaf cottonwood, Populus angustifolia, a dominant riparian tree. Using multi-locus surveys of polymorphism in 363 individuals across the species' 1800 km latitudinal range, we found that, first, P. angustifolia has stronger neutral genetic structure than many forest trees (simple sequence repeat (SSR) FST=0.21), with major genetic groups corresponding to large apparent geographical barriers to gene flow. Second, using SSRs and putatively neutral sequenced loci, coalescent simulations indicated that populations diverged before the last glacial maximum (LGM), suggesting the presence of population structure before the LGM. Third, the LGM and subsequent warming appear to have had different influences on each of these distinct populations, with effective population size reduction in the southern extent of the range but major expansion in the north. These results are consistent with the hypothesis that climate and geographic barriers have jointly affected the demographic history of P. angustifolia, and point the importance of both factors as being instrumental in shaping genetic variation and structure in widespread forest trees. PMID:25585921

  4. Rural Household Demographics, Livelihoods and the Environment

    PubMed Central

    de Sherbinin, Alex; VanWey, Leah; McSweeney, Kendra; Aggarwal, Rimjhim; Barbieri, Alisson; Henry, Sabina; Hunter, Lori M.; Twine, Wayne

    2008-01-01

    This paper reviews and synthesizes findings from scholarly work on linkages among rural household demographics, livelihoods and the environment. Using the livelihood approach as an organizing framework, we examine evidence on the multiple pathways linking environmental variables and the following demographic variables: fertility, migration, morbidity and mortality, and lifecycles. Although the review draws on studies from the entire developing world, we find the majority of micro-level studies have been conducted in either marginal (mountainous or arid) or frontier environments, especially Amazonia. Though the linkages are mediated by many complex and often context-specific factors, there is strong evidence that dependence on natural resources intensifies when households lose human and social capital through adult morbidity and mortality, and qualified evidence for the influence of environmental factors on household decision-making regarding fertility and migration. Two decades of research on lifecycles and land-cover change at the farm level have yielded a number of insights about how households make use of different land-use and natural resource management strategies at different stages. A thread running throughout the review is the importance of managing risk through livelihood diversification, ensuring future income security, and culture-specific norms regarding appropriate and desirable activities and demographic responses. Recommendations for future research are provided. PMID:19190718

  5. Entropy Based Modelling for Estimating Demographic Trends

    PubMed Central

    Kuo, Shyh-Hao; Xu, Hai-Yan; Hu, Nan; Zhao, Guangshe; Monterola, Christopher

    2015-01-01

    In this paper, an entropy-based method is proposed to forecast the demographical changes of countries. We formulate the estimation of future demographical profiles as a constrained optimization problem, anchored on the empirically validated assumption that the entropy of age distribution is increasing in time. The procedure of the proposed method involves three stages, namely: 1) Prediction of the age distribution of a country’s population based on an “age-structured population model”; 2) Estimation the age distribution of each individual household size with an entropy-based formulation based on an “individual household size model”; and 3) Estimation the number of each household size based on a “total household size model”. The last stage is achieved by projecting the age distribution of the country’s population (obtained in stage 1) onto the age distributions of individual household sizes (obtained in stage 2). The effectiveness of the proposed method is demonstrated by feeding real world data, and it is general and versatile enough to be extended to other time dependent demographic variables. PMID:26382594

  6. Rural Household Demographics, Livelihoods and the Environment.

    PubMed

    de Sherbinin, Alex; Vanwey, Leah; McSweeney, Kendra; Aggarwal, Rimjhim; Barbieri, Alisson; Henry, Sabina; Hunter, Lori M; Twine, Wayne

    2008-02-01

    This paper reviews and synthesizes findings from scholarly work on linkages among rural household demographics, livelihoods and the environment. Using the livelihood approach as an organizing framework, we examine evidence on the multiple pathways linking environmental variables and the following demographic variables: fertility, migration, morbidity and mortality, and lifecycles. Although the review draws on studies from the entire developing world, we find the majority of micro-level studies have been conducted in either marginal (mountainous or arid) or frontier environments, especially Amazonia. Though the linkages are mediated by many complex and often context-specific factors, there is strong evidence that dependence on natural resources intensifies when households lose human and social capital through adult morbidity and mortality, and qualified evidence for the influence of environmental factors on household decision-making regarding fertility and migration. Two decades of research on lifecycles and land-cover change at the farm level have yielded a number of insights about how households make use of different land-use and natural resource management strategies at different stages. A thread running throughout the review is the importance of managing risk through livelihood diversification, ensuring future income security, and culture-specific norms regarding appropriate and desirable activities and demographic responses. Recommendations for future research are provided. PMID:19190718

  7. Demographic factors predict magnitude of conditioned fear.

    PubMed

    Rosenbaum, Blake L; Bui, Eric; Marin, Marie-France; Holt, Daphne J; Lasko, Natasha B; Pitman, Roger K; Orr, Scott P; Milad, Mohammed R

    2015-10-01

    There is substantial variability across individuals in the magnitudes of their skin conductance (SC) responses during the acquisition and extinction of conditioned fear. To manage this variability, subjects may be matched for demographic variables, such as age, gender and education. However, limited data exist addressing how much variability in conditioned SC responses is actually explained by these variables. The present study assessed the influence of age, gender and education on the SC responses of 222 subjects who underwent the same differential conditioning paradigm. The demographic variables were found to predict a small but significant amount of variability in conditioned responding during fear acquisition, but not fear extinction learning or extinction recall. A larger differential change in SC during acquisition was associated with more education. Older participants and women showed smaller differential SC during acquisition. Our findings support the need to consider age, gender and education when studying fear acquisition but not necessarily when examining fear extinction learning and recall. Variability in demographic factors across studies may partially explain the difficulty in reproducing some SC findings. PMID:26151498

  8. Stochastic game dynamics under demographic fluctuations

    PubMed Central

    Huang, Weini; Hauert, Christoph; Traulsen, Arne

    2015-01-01

    Frequency-dependent selection and demographic fluctuations play important roles in evolutionary and ecological processes. Under frequency-dependent selection, the average fitness of the population may increase or decrease based on interactions between individuals within the population. This should be reflected in fluctuations of the population size even in constant environments. Here, we propose a stochastic model that naturally combines these two evolutionary ingredients by assuming frequency-dependent competition between different types in an individual-based model. In contrast to previous game theoretic models, the carrying capacity of the population, and thus the population size, is determined by pairwise competition of individuals mediated by evolutionary games and demographic stochasticity. In the limit of infinite population size, the averaged stochastic dynamics is captured by deterministic competitive Lotka–Volterra equations. In small populations, demographic stochasticity may instead lead to the extinction of the entire population. Because the population size is driven by fitness in evolutionary games, a population of cooperators is less prone to go extinct than a population of defectors, whereas in the usual systems of fixed size the population would thrive regardless of its average payoff. PMID:26150518

  9. Entropy Based Modelling for Estimating Demographic Trends.

    PubMed

    Li, Guoqi; Zhao, Daxuan; Xu, Yi; Kuo, Shyh-Hao; Xu, Hai-Yan; Hu, Nan; Zhao, Guangshe; Monterola, Christopher

    2015-01-01

    In this paper, an entropy-based method is proposed to forecast the demographical changes of countries. We formulate the estimation of future demographical profiles as a constrained optimization problem, anchored on the empirically validated assumption that the entropy of age distribution is increasing in time. The procedure of the proposed method involves three stages, namely: 1) Prediction of the age distribution of a country's population based on an "age-structured population model"; 2) Estimation the age distribution of each individual household size with an entropy-based formulation based on an "individual household size model"; and 3) Estimation the number of each household size based on a "total household size model". The last stage is achieved by projecting the age distribution of the country's population (obtained in stage 1) onto the age distributions of individual household sizes (obtained in stage 2). The effectiveness of the proposed method is demonstrated by feeding real world data, and it is general and versatile enough to be extended to other time dependent demographic variables. PMID:26382594

  10. Stochastic game dynamics under demographic fluctuations.

    PubMed

    Huang, Weini; Hauert, Christoph; Traulsen, Arne

    2015-07-21

    Frequency-dependent selection and demographic fluctuations play important roles in evolutionary and ecological processes. Under frequency-dependent selection, the average fitness of the population may increase or decrease based on interactions between individuals within the population. This should be reflected in fluctuations of the population size even in constant environments. Here, we propose a stochastic model that naturally combines these two evolutionary ingredients by assuming frequency-dependent competition between different types in an individual-based model. In contrast to previous game theoretic models, the carrying capacity of the population, and thus the population size, is determined by pairwise competition of individuals mediated by evolutionary games and demographic stochasticity. In the limit of infinite population size, the averaged stochastic dynamics is captured by deterministic competitive Lotka-Volterra equations. In small populations, demographic stochasticity may instead lead to the extinction of the entire population. Because the population size is driven by fitness in evolutionary games, a population of cooperators is less prone to go extinct than a population of defectors, whereas in the usual systems of fixed size the population would thrive regardless of its average payoff. PMID:26150518

  11. European economic restructuring: demographic responses and feedbacks.

    PubMed

    Blotevogel, H H; King, R

    1996-01-01

    The relationship between economic restructuring in Europe and various aspects of demographic change, such as demographic aging and fertility decline, is examined. The focus is on changes in the labor market. "Changing employment conditions--the growth of the secondary labour market, the flexibilization of labour demand and increasingly also of supply, growing female labour force participation rates, generally high ethnic minority unemployment--reflect different aspects of the transition from the Fordist to the postFordist regime as well as changing demographic and life-style influences. Together they have deeply transformed the European landscape of employment and unemployment. The specific role of international migration is also analysed and it is seen to have fundamentally altered between the Fordist and postFordist eras. Less clear to interpret are changing internal migration patterns: has counterurbanization stopped in response to restructuring and integration and is a new postFordist population map unfolding? The paper concludes by evaluating the nature of the relationship between economic restructuring and population trends and identifying pointers for future research." PMID:12293416

  12. Atom cooling by nonadiabatic expansion

    SciTech Connect

    Chen Xi; Muga, J. G.; Campo, A. del; Ruschhaupt, A.

    2009-12-15

    Motivated by the recent discovery that a reflecting wall moving with a square-root-in-time trajectory behaves as a universal stopper of classical particles regardless of their initial velocities, we compare linear-in-time and square-root-in-time expansions of a box to achieve efficient atom cooling. For the quantum single-atom wave functions studied the square-root-in-time expansion presents important advantages: asymptotically it leads to zero average energy whereas any linear-in-time (constant box-wall velocity) expansion leaves a nonzero residual energy, except in the limit of an infinitely slow expansion. For finite final times and box lengths we set a number of bounds and cooling principles which again confirm the superior performance of the square-root-in-time expansion, even more clearly for increasing excitation of the initial state. Breakdown of adiabaticity is generally fatal for cooling with the linear expansion but not so with the square-root-in-time expansion.

  13. [The keys to the western demographic "miracle"].

    PubMed

    Burguiere, A

    1991-09-01

    Unlike most historical disciplines which had access to copious sources of data before refining their analytical methods, historical demography has almost simultaneously acquired data and developed rigorous analytical methods. French parish records did not attract detailed scrutiny until after World War II, but family reconstitution and other methods of exploitation were soon perfected. The continuing paradox of historical demography is that its statistical methods are rigorous but data remain sparse. Several dozen villages and a few cities have emerged from a vast obscurity but entire regions remain unexplored. Nonetheless, the study of preindustrial populations has progressed more in the past 20 years than has study of populations in the industrial era. Complex phenomena such as the fertility decline and incipient control of birth rates in late 18th century Europe have been studied or explained more adequately than has the inverse phenomenon, the baby boom of the 1940s. A major impetus to historical demography in Europe was the desire of demographers at the National Institute of Demographic Studies to understand Europe's fertility decline through knowledge of the mechanisms that initially caused it to occur. The diversity of apparent demographic models that have resulted from the works of historical demographers has caused various regional models to be proposed for France in the 17th and 18th centuries. It is clear from statistical analysis of available data that by the 18th century, fertility control was practiced by the mass of the French population, but the interpretation of this fact is problematic. The change in fertility behavior must reflect a deeper change in mentalities. The diffusion of contraception in the 18th century did not represent a transgression of the teachings of the Catholic Church as much as a change in attitudes toward life in which the future security of children was increasingly sought in education and improved living standards, and in

  14. Thermal Expansion of Polyurethane Foam

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.; Sullivan, Roy M.

    2006-01-01

    Closed cell foams are often used for thermal insulation. In the case of the Space Shuttle, the External Tank uses several thermal protection systems to maintain the temperature of the cryogenic fuels. A few of these systems are polyurethane, closed cell foams. In an attempt to better understand the foam behavior on the tank, we are in the process of developing and improving thermal-mechanical models for the foams. These models will start at the microstructural level and progress to the overall structural behavior of the foams on the tank. One of the key properties for model characterization and verification is thermal expansion. Since the foam is not a material, but a structure, the modeling of the expansion is complex. It is also exacerbated by the anisoptropy of the material. During the spraying and foaming process, the cells become elongated in the rise direction and this imparts different properties in the rise direction than in the transverse directions. Our approach is to treat the foam as a two part structure consisting of the polymeric cell structure and the gas inside the cells. The polymeric skeleton has a thermal expansion of its own which is derived from the basic polymer chemistry. However, a major contributor to the thermal expansion is the volume change associated with the gas inside of the closed cells. As this gas expands it exerts pressure on the cell walls and changes the shape and size of the cells. The amount that this occurs depends on the elastic and viscoplastic properties of the polymer skeleton. The more compliant the polymeric skeleton, the more influence the gas pressure has on the expansion. An additional influence on the expansion process is that the polymeric skeleton begins to breakdown at elevated temperatures and releases additional gas species into the cell interiors, adding to the gas pressure. The fact that this is such a complex process makes thermal expansion ideal for testing the models. This report focuses on the thermal

  15. DEMOGRAPHIC UNCERTAINTY IN ECOLOGICAL RISK ASSESSMENTS. (R825347)

    EPA Science Inventory

    We built a Ricker's model incorporating demographic stochasticity to simulate the effects of demographic uncertainty on responses of gray-tailed vole (Microtus canicaudus) populations to pesticide applications. We constructed models with mark-recapture data collected from populat...

  16. Demographics, Dollars and Difficulties in Graduate Education.

    ERIC Educational Resources Information Center

    Atkinson, Richard C.

    In a discussion of the crisis in graduate education in the sciences and engineering, focus is on factors that threaten American capability to produce world-class science in universities. While finances play a part, the causes are basically structural--the rigidity of university faculties, stemming from a significant expansion in tenured positions,…

  17. Mapping populations at risk: improving spatial demographic data for infectious disease modeling and metric derivation.

    PubMed

    Tatem, Andrew J; Adamo, Susana; Bharti, Nita; Burgert, Clara R; Castro, Marcia; Dorelien, Audrey; Fink, Gunter; Linard, Catherine; John, Mendelsohn; Montana, Livia; Montgomery, Mark R; Nelson, Andrew; Noor, Abdisalan M; Pindolia, Deepa; Yetman, Greg; Balk, Deborah

    2012-01-01

    The use of Global Positioning Systems (GPS) and Geographical Information Systems (GIS) in disease surveys and reporting is becoming increasingly routine, enabling a better understanding of spatial epidemiology and the improvement of surveillance and control strategies. In turn, the greater availability of spatially referenced epidemiological data is driving the rapid expansion of disease mapping and spatial modeling methods, which are becoming increasingly detailed and sophisticated, with rigorous handling of uncertainties. This expansion has, however, not been matched by advancements in the development of spatial datasets of human population distribution that accompany disease maps or spatial models.Where risks are heterogeneous across population groups or space or dependent on transmission between individuals, spatial data on human population distributions and demographic structures are required to estimate infectious disease risks, burdens, and dynamics. The disease impact in terms of morbidity, mortality, and speed of spread varies substantially with demographic profiles, so that identifying the most exposed or affected populations becomes a key aspect of planning and targeting interventions. Subnational breakdowns of population counts by age and sex are routinely collected during national censuses and maintained in finer detail within microcensus data. Moreover, demographic and health surveys continue to collect representative and contemporary samples from clusters of communities in low-income countries where census data may be less detailed and not collected regularly. Together, these freely available datasets form a rich resource for quantifying and understanding the spatial variations in the sizes and distributions of those most at risk of disease in low income regions, yet at present, they remain unconnected data scattered across national statistical offices and websites.In this paper we discuss the deficiencies of existing spatial population datasets and

  18. Understanding and Using Demographic Data: Terms and Measures.

    ERIC Educational Resources Information Center

    Lilley, Stephen

    This publication provides program planners and others with information and analytical tools for using demographic data in program planning, implementation, and evaluation. The report reviews the importance of demographic data and their relevance to programs and proper implementation of laws, discusses the collection of demographic information by…

  19. Can Establishment Success Be Determined through Demographic Parameters? A Case Study on Five Introduced Bird Species

    PubMed Central

    Sanz-Aguilar, Ana; Anadón, José D.; Edelaar, Pim; Carrete, Martina; Tella, José Luis

    2014-01-01

    The dominant criterion to determine when an introduced species is established relies on the maintenance of a self-sustaining population in the area of introduction, i.e. on the viability of the population from a demographic perspective. There is however a paucity of demographic studies on introduced species, and establishment success is thus generally determined by expert opinion without undertaking population viability analyses (PVAs). By means of an intensive five year capture-recapture monitoring program (involving >12,000 marked individuals) we studied the demography of five introduced passerine bird species in southern Spain which are established and have undergone a fast expansion over the last decades. We obtained useful estimates of demographic parameters (survival and reproduction) for one colonial species (Ploceus melanocephalus), confirming the long-term viability of its local population through PVAs. However, extremely low recapture rates prevented the estimation of survival parameters and population growth rates for widely distributed species with low local densities (Estrilda troglodytes and Amandava amandava) but also for highly abundant yet non-colonial species (Estrilda astrild and Euplectes afer). Therefore, determining the establishment success of introduced passerine species by demographic criteria alone may often be troublesome even when devoting much effort to field-work. Alternative quantitative methodologies such as the analysis of spatio-temporal species distributions complemented with expert opinion deserve thus their role in the assessment of establishment success of introduced species when estimates of demographic parameters are difficult to obtain, as is generally the case for non-colonial, highly mobile passerines. PMID:25333743

  20. Range Expansion of Heterogeneous Populations

    NASA Astrophysics Data System (ADS)

    Reiter, Matthias; Rulands, Steffen; Frey, Erwin

    2014-04-01

    Risk spreading in bacterial populations is generally regarded as a strategy to maximize survival. Here, we study its role during range expansion of a genetically diverse population where growth and motility are two alternative traits. We find that during the initial expansion phase fast-growing cells do have a selective advantage. By contrast, asymptotically, generalists balancing motility and reproduction are evolutionarily most successful. These findings are rationalized by a set of coupled Fisher equations complemented by stochastic simulations.

  1. Warp drive with zero expansion

    NASA Astrophysics Data System (ADS)

    Natário, José

    2002-03-01

    It is commonly believed that Alcubierre's warp drive works by contracting space in front of the warp bubble and expanding the space behind it. We show that this contraction/expansion is but a marginal consequence of the choice made by Alcubierre and explicitly construct a similar spacetime where no contraction/expansion occurs. Global and optical properties of warp-drive spacetimes are also discussed.

  2. Environment, migration and the European demographic deficit

    NASA Astrophysics Data System (ADS)

    Harper, Sarah

    2012-03-01

    Many countries in the more developed world, and some in the less developed, are facing new economic and social pressures associated with the ageing of their populations. Europe, in particular, is forecast to have a demographic deficit, which may be alleviated by in-migration to the region. However, several commentators have proposed that Europe will not be able to successfully compete with other regions, in particular Asia, in the coming years for the skills it will require. This letter explores these themes, arguing that climate change will increase the attractiveness of Europe as a destination of economic choice for future skilled workers, to the detriment of more environmentally challenged regions.

  3. Rock expansion caused by ultrasound

    NASA Astrophysics Data System (ADS)

    Hedberg, C.; Gray, A.

    2013-12-01

    It has during many years been reported that materials' elastic modulus decrease when exposed to influences like mechanical impacts, ultrasound, magnetic fields, electricity and even humidity. Non-perfect atomic structures like rocks, concrete, or damaged metals exhibit a larger effect. This softening has most often been recorded by wave resonance measurements. The motion towards equilibrium is slow - often taking hours or days, which is why the effect is called Slow Dynamics [1]. The question had been raised, if a material expansion also occurs. 'The most fundamental parameter to consider is the volume expansion predicted to occur when positive hole charge carriers become activated, causing a decrease of the electron density in the O2- sublattice of the rock-forming minerals. This decrease of electron density should affect essentially all physical parameters, including the volume.' [2]. A new type of configuration has measured expansion of a rock subjected to ultrasound. A PZT was used as a pressure sensor while the combined thickness of the rock sample and the PZT sensor was held fixed. The expansion increased the stress in both the rock and the PZT, which gave an out-put voltage from the PZT. Knowing its material properties then made it possible to calculate the rock expansion. The equivalent strain caused by the ultrasound was approximately 3 x 10-5. The temperature was monitored and accounted for during the tests and for the maximum expansion the increase was 0.7 C, which means the expansion is at least to some degree caused by heating of the material by the ultrasound. The fraction of bonds activated by ultrasound was estimated to be around 10-5. References: [1] Guyer, R.A., Johnson, P.A.: Nonlinear Mesoscopic Elasticity: The Complex Behaviour of Rocks, Soils, Concrete. Wiley-VCH 2009 [2] M.M. Freund, F.F. Freund, Manipulating the Toughness of Rocks through Electric Potentials, Final Report CIF 2011 Award NNX11AJ84A, NAS Ames 2012.

  4. Profile: Nanoro Health and Demographic Surveillance System.

    PubMed

    Derra, Karim; Rouamba, Eli; Kazienga, Adama; Ouedraogo, Sayouba; Tahita, Marc C; Sorgho, Hermann; Valea, Innocent; Tinto, Halidou

    2012-10-01

    The Nanoro Health and Demographic Surveillance System (HDSS), located in the rural centre of Burkina Faso, was established in 2009 by the Clinical Research Unit of Nanoro with the aim of providing a core framework for clinical trials and also to support the Burkina Faso health authorities in generating epidemiological data that can contribute to the setup and assessment of health interventions. In the baseline of initial census, 54 781 individuals were recorded of whom 56.1% are female. After the initial census, vital events such as pregnancies, births, migrations and deaths have been monitored, and data on individuals and household characteristics are updated during regular 4-monthly household visits. The available data are categorized into demographic, cultural, socio-economic and health information, and are used for monitoring and evaluation of population development issues. As a young site, our objective has been to strengthen our skills and knowledge and share new scientific experiences with INDEPTH and HDSS sites in Burkina Faso. In addition, all data produced by the Nanoro HDSS will be made publicly available through the INDEPTH data sharing system. PMID:23045201

  5. Demographic history and genetic differentiation in apes.

    PubMed

    Fischer, Anne; Pollack, Joshua; Thalmann, Olaf; Nickel, Birgit; Pääbo, Svante

    2006-06-01

    Comparisons of genetic variation between humans and great apes are hampered by the fact that we still know little about the demographics and evolutionary history of the latter species. In addition, characterizing ape genetic variation is important because they are threatened with extinction, and knowledge about genetic differentiation among groups may guide conservation efforts. We sequenced multiple intergenic autosomal regions totaling 22,400 base pairs (bp) in ten individuals each from western, central, and eastern chimpanzee groups and in nine bonobos, and 16,000 bp in ten Bornean and six Sumatran orangutans. These regions are analyzed together with homologous information from three human populations and gorillas. We find that whereas orangutans have the highest diversity, western chimpanzees have the lowest, and that the demographic histories of most groups differ drastically. Special attention should therefore be paid to sampling strategies and the statistics chosen when comparing levels of variation within and among groups. Finally, we find that the extent of genetic differentiation among "subspecies" of chimpanzees and orangutans is comparable to that seen among human populations, calling the validity of the "subspecies" concept in apes into question. PMID:16753568

  6. The position of women and demographic policy.

    PubMed

    Kiseleva, G

    1981-01-01

    This article analyzes the effect of women's social roles on fertility and the possibilities of influencing fertility by means of demographic policies in the USSR. The most important influences on the birth rate are related to the changing social position of women and the functions of the family which have resulted from social, economic, and cultural transformations in the Soviet state since the revolution. The processes of industrialization, urbanization, higher labor productivity, and rising educational and cultural standards have removed the productive functions of the family and have also altered its consumer functions. The upbringing of children is increasingly labor intensive because of the need for more educated, higher quality workers. In 1970, 82% of women of working age were employed; their greater involvement in social production and reduced free time, combined with the prestige and economic and social independence gained from outside work, have encouraged a small family orientation. Comprehensive demographic policies including measures to help women combine work in social production with motherhood are needed to promote 2 or 3 child families. Along with measures aimed at the population as a whole, specific measures are needed that take into account the distinctive life styles and behavior of separate local population groups. A socialist society with a planned economy can utilize diverse methods of encouraging childbirth, including material assistance to families with children and sociopsychological measures to promote larger families. PMID:12264275

  7. Rwanda: a case of demographic entrapment.

    PubMed

    Bonneux, L

    1994-12-17

    When King published 3 articles about demographic entrapment, he recommended that primary health care stop targeting child mortality, indeed that oral rehydration solutions be withheld, in order to reduce population size and evade the demographic trap of a region endangered by the growth of its own population. Using Rwanda as an example, it is possible to calculate the effect of decreasing child mortality on population growth. From 1970, when there were no programs to reduce child mortality, until 1993 the birth rate remained constant and the child mortality rate slowed so that an extra 0.5/5 children would survive to their fifth birthday. Thus, most of the population growth increase of 0.5% is probably attributable to decreased child mortality. If the high mortality rate had been maintained, the growth rate would have remained at 2.9% and the population doubling time would have been 24.2 years. The actual doubling time between 1970 and 1993 was 22.1 years, so only 2 years would have been gained by increased child mortality. The problem in Rwanda was not decreased child mortality, therefore, but the constant birth rate. Rwanda has a very Catholic population which embraces the Roman Catholic Church's anti-family planning policy. It is very hard for illiterate poor to refute the teachings of the church. The collapse of Rwanda caused by its overpopulation presents an example to the world of the devastating consequences of denying effective family planning to the poor. PMID:7996966

  8. Demographic correlates of attenuated positive psychotic symptoms

    PubMed Central

    Waford, Rachel N.; MacDonald, Allison; Goines, Katrina; Novacek, Derek M.; Trotman, Hanan D.; Walker, Elaine F.; Addington, Jean; Bearden, Carrie E.; Cadenhead, Kristin S.; Cannon, Tyrone D.; Cornblatt, Barbara A.; Heinssen, Robert; Mathalon, Daniel H.; Tsuang, Ming T.; Perkins, Diana O.; Seidman, Larry J.; Woods, Scott W.; McGlashan, Thomas H.

    2015-01-01

    It is now well established that the utilization of standardized clinical criteria can enhance prediction of psychosis. These criteria are primarily concerned with the presence and severity of attenuated positive symptoms. Because these symptom criteria are used to derive algorithms for designating clinical high risk (CHR) status and for maximizing prediction of psychosis risk, it is important to know whether the symptom ratings vary as a function of demographic factors that have previously been linked with symptoms in diagnosed psychotic patients. Using a sample of 356 CHR individuals from the NAPLS-II multi-site study, we examined the relation of three sex, age, and educational level, with the severity of attenuated positive symptom scores from the Scale of Prodromal Symptoms (SOPS). Demographic factors accounted for little of the variance in symptom ratings (5–6%). Older CHR individuals manifested more severe suspiciousness, and female CHR participants reported more unusual perceptual experiences than male participants. Contrary to prediction, higher educational level was associated with more severe ratings of unusual thought content, but less severe perceptual abnormalities. Overall, sex, age and education were modestly related to unusual thought content and perceptual abnormalities, only, suggesting minimal implication for designating CHR status and predicting psychosis-risk. PMID:25999040

  9. The AAVSO 2011 Demographic and Background Survey

    NASA Astrophysics Data System (ADS)

    Price, A.

    2012-04-01

    In 2011, the AAVSO conducted a survey of 615 people who are or were recently active in the organization. The survey included questions about their demographic background and variable star interests. Data are descriptively analyzed and compared with prior surveys. Results show an organization of very highly educated, largely male amateur and professional astronomers distributed across 108 countries. Participants tend to be loyal, with the average time of involvement in the AAVSO reported as 14 years. Most major demographic factors have not changed much over time. However, the average age of new members is increasing. Also, a significant portion of the respondents report being strictly active in a non-observing capacity, reflecting the growing mission of the organization. Motivations of participants are more aligned with scientific contribution than with that reported by other citizen science projects. This may help explain why a third of all respondents are an author or co-author of a paper in an astronomical journal. Finally, there is some evidence that participation in the AAVSO has a greater impact on the respondents' view of their role in astronomy compared to that expected through increasing amateur astronomy experience alone.

  10. Incidence and Demographics of Childhood Ptosis

    PubMed Central

    Griepentrog, Gregory J.; Diehl, Nancy; Mohney, Brian G.

    2012-01-01

    Purpose To report the incidence and demographics of childhood ptosis diagnosed over a 40-year period in a well-defined population. Design Retrospective, population-based cohort study. Participants Patients (< 19 years) diagnosed with childhood ptosis as residents of Olmsted County, Minnesota, from January 1, 1965, through December 31, 2004 Methods The medical records of all potential patients identified by the Rochester Epidemiology Project were reviewed. Main Outcome Measures Calculated annual age- and sex-specific incidence rates and demographic information. Results A total of 107 children were diagnosed with ptosis during the 40-year period, yielding an incidence of 7.9/100,000 < 19 years (95% confidence interval [CI]: 6.4-9.5) of age. Ninety-six (89.7%) of the 107 were congenital in onset, 81 (75%) of which had simple congenital ptosis, yielding a birth prevalence of 1 in 842 births. A family history of childhood ptosis was present in twelve percent of queried patients with simple congenital ptosis. Three (4%) of the simple congenital ptosis cases were bilateral and 55 (68%) of the unilateral cases involved the left upper eyelid (95% CI: 57%-78%, p<0.001). Conclusion Childhood ptosis was diagnosed in 7.9 per 100,000 patients less than 19 years (95% CI: 6.4-9.5). Simple congenital ptosis was the most prevalent form, occurring in 1 in 842 births, and significantly more likely to involve the left side. PMID:21496927

  11. Prospective Demographic Study of Cosmetic Surgery Patients

    PubMed Central

    Schlessinger, Daniel; Schlessinger, Bernard

    2010-01-01

    Objectives: The authors sought to examine and assess cosmetic surgery patient demographics as well as age in relation to partner, in a prospective manner, analyzing data for any significant correlations. Design: The authors conducted a prospective study utilizing a survey. Setting: The study was conducted in a private, nonacademic dermatological practice. Participants: Three hundred thirty-six patients participated in this study. Results: Demographics of onabotulinumtoxinA/abobotulinumtoxinA (neurotoxins), fillers, and laser hair removal users were studied. The data show that the average private practice cosmetic surgery patient in this study is a married (67.5%), college-educated or greater (66.9%), employed (74.3%), mother (74.5%). In the fillers category, 50 percent of women were older than their partners, as opposed to 14.8 percent in 2008 Census data. Additionally, women were more educated and employed to a higher percentage than similar women in 2008 Census data. Data on motivations were statistically not significant. Conclusion: Data from this study show potential correlations with Census data norms in marital status and motherhood status categories, but not in the age in relation to partner, education, and employment level categories. Motivations of individuals undergoing cosmetic surgery will need further analysis in future studies. PMID:21103314

  12. The use of mobile phones for demographic surveillance of mobile pastoralists and their animals in Chad: proof of principle

    PubMed Central

    Jean-Richard, Vreni; Crump, Lisa; Daugla, Doumagoum Moto; Hattendorf, Jan; Schelling, Esther; Zinsstag, Jakob

    2014-01-01

    Background Demographic information is foundational for the planning and management of social programmes, in particular health services. The existing INDEPTH network surveillance sites are limited to coverage of sedentary populations. Including mobile populations in this approach would be expensive, time consuming and possibly low in accuracy. Very little is known about the demography of mobile pastoralists and their animals, so innovative approaches are urgently needed. Objective To test and evaluate a mobile demographic surveillance system for mobile pastoralist households, including livestock herds, using mobile phones. Design Mobile pastoralist camps were monitored (10 for 12 months and 10 for 18 months) using biweekly mobile phone calls with camp leaders and their wives to conduct interviews about the households and livestock. The collected information was validated through personal visits, GPS data and a livestock demographic model. Results The study showed the feasibility of mobile phone surveillance for mobile pastoralist camps, providing usable, valid information on human and livestock population structures, pregnancy outcomes and herd dynamics, as well as migration patterns. The approach was low-cost and applicable with the existing local resources. Conclusion Demographic surveillance in mobile populations is feasible using mobile phones. Expansion of the small-scale system into a full mobile demographic surveillance system is warranted and would likely lead to improved planning and provision of human and animal health care. PMID:24499744

  13. Inferring population structure and demographic history using Y-STR data from worldwide populations.

    PubMed

    Xu, Hongyang; Wang, Chuan-Chao; Shrestha, Rukesh; Wang, Ling-Xiang; Zhang, Manfei; He, Yungang; Kidd, Judith R; Kidd, Kenneth K; Jin, Li; Li, Hui

    2015-02-01

    The Y chromosome is one of the best genetic materials to explore the evolutionary history of human populations. Global analyses of Y chromosomal short tandem repeats (STRs) data can reveal very interesting world population structures and histories. However, previous Y-STR works tended to focus on small geographical ranges or only included limited sample sizes. In this study, we have investigated population structure and demographic history using 17 Y chromosomal STRs data of 979 males from 44 worldwide populations. The largest genetic distances have been observed between pairs of African and non-African populations. American populations with the lowest genetic diversities also showed large genetic distances and coancestry coefficients with other populations, whereas Eurasian populations displayed close genetic affinities. African populations tend to have the oldest time to the most recent common ancestors (TMRCAs), the largest effective population sizes and the earliest expansion times, whereas the American, Siberian, Melanesian, and isolated Atayal populations have the most recent TMRCAs and expansion times, and the smallest effective population sizes. This clear geographic pattern is well consistent with serial founder model for the origin of populations outside Africa. The Y-STR dataset presented here provides the most detailed view of worldwide population structure and human male demographic history, and additionally will be of great benefit to future forensic applications and population genetic studies. PMID:25159112

  14. Demographics: Diversity in More Forms. Student Demographics, Now and the Future.

    ERIC Educational Resources Information Center

    Windham, Patricia; And Others

    While demographic diversity among the student body has increased substantially over the past several decades, the academic, economic, and social diversity of students will play a greater part in upcoming staffing and faculty requirements at community colleges. Data from Tallahassee Community College (TCC), in Florida, from 1980 to 1994 indicate…

  15. Multilocus Analyses Reveal Postglacial Demographic Shrinkage of Juniperus morrisonicola (Cupressaceae), a Dominant Alpine Species in Taiwan

    PubMed Central

    Chiu, Chi-Te; Huang, Chao-Li; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh

    2016-01-01

    Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration. PMID:27561108

  16. A new method for estimating the demographic history from DNA sequences: an importance sampling approach

    PubMed Central

    Ait Kaci Azzou, Sadoune; Larribe, Fabrice; Froda, Sorana

    2015-01-01

    The effective population size over time (demographic history) can be retraced from a sample of contemporary DNA sequences. In this paper, we propose a novel methodology based on importance sampling (IS) for exploring such demographic histories. Our starting point is the generalized skyline plot with the main difference being that our procedure, skywis plot, uses a large number of genealogies. The information provided by these genealogies is combined according to the IS weights. Thus, we compute a weighted average of the effective population sizes on specific time intervals (epochs), where the genealogies that agree more with the data are given more weight. We illustrate by a simulation study that the skywis plot correctly reconstructs the recent demographic history under the scenarios most commonly considered in the literature. In particular, our method can capture a change point in the effective population size, and its overall performance is comparable with the one of the bayesian skyline plot. We also introduce the case of serially sampled sequences and illustrate that it is possible to improve the performance of the skywis plot in the case of an exponential expansion of the effective population size. PMID:26300910

  17. Demographic variation and conservation of the narrow endemic plant Ranunculus weyleri

    NASA Astrophysics Data System (ADS)

    Cursach, Joana; Besnard, Aurélien; Rita, Juan; Fréville, Hélène

    2013-11-01

    Ranunculus weyleri is a narrow endemic protected plant from Majorca Island. It is known from only five populations located in two mountain areas 48 km apart. Using demographic data collected from 2007 to 2010, we assessed the demographic status of two populations - font des Coloms (FC) and talaia Moreia (TM) - using Integral Projection Models (IPMs). We showed that none of the two populations were declining under a deterministic model. Population FC was stable (λ = 1.026, CI95% = 0.965-1.093), while population TM showed sign of demographic expansion (λ = 1.113, CI95% = 1.032-1.219). Plant survival, flowering probability and the mean number of seedlings per floral peduncle were lower in TM, whereas growth and the number of floral peduncles per reproductive plant were lower in FC. Elasticity analyses showed that management strategies increasing plant survival and growth would be the most efficient to increase λ for both populations. Herbivory pressure by goats has been shown to be high in TM, resulting in high predation rate on floral peduncles. Controlling goat pressure may thus represent a promising management option, provided that we can demonstrate a negative impact of herbivory by goats on survival and growth which are the most critical parts of the life cycle in this species. Meanwhile, initiating a long-term monitoring is of crucial importance to get more insights into the relationships between environmental variation, plant performance and population dynamics.

  18. Multilocus Analyses Reveal Postglacial Demographic Shrinkage of Juniperus morrisonicola (Cupressaceae), a Dominant Alpine Species in Taiwan.

    PubMed

    Huang, Chi-Chun; Hsu, Tsai-Wen; Wang, Hao-Ven; Liu, Zin-Huang; Chen, Yi-Yen; Chiu, Chi-Te; Huang, Chao-Li; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh

    2016-01-01

    Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration. PMID:27561108

  19. Low thermal expansion poreless ceramics

    NASA Astrophysics Data System (ADS)

    Sugawara, Jun; Abe, Kozo; Mukai, Toshio

    2003-05-01

    Low thermal expansion ceramics have been required for ultra precision nanometer positioning stage in the semiconductor equipments. Especially pore-less advanced ceramics have been playng an important part as mirror materials in the optical equipments. Nippon Steel produces Sialon and NEXCERA as the solutions for these demands. Sialon based on silicon nitride shows a thermal expansion of 1.3 x 10-6/K with a high Young's modulus of 300 GPa. Newly-developed NEXCERA based on cordierite ceramics shows near-zero thermal expansion around the room temperature with a Young's modulus of 130 GPa. For these advanced ceramics, near-net shape sintering, direct bonding and mirror polishing are available. These technologies will provide us new design possibilities in precision engineering fields like optical system.

  20. Cylinder Expansion in Polypropylene Tubes

    NASA Astrophysics Data System (ADS)

    Pemberton, Steven; Tappan, Bryce; Manner, Virginia

    2015-06-01

    Cylinder Expansion has long been the benchmark test used to establish an equation of state for any detonable energetic material. However, some new explosives have properties that prevent the use of the traditional copper-walled test; two such issues are materials whose detonations proceed more slowly than the acoustic velocity in the copper liner, and materials with failure diameters large enough to render copper testing prohibitively expensive. Results are presented for experiments conducted using a stoichiometric mixture of ammonium perchlorate and dodecane, a slow-detonating explosive. In copper walls inconsistent expansion was observed due to acoustic precursor waves within the wall. Additional testing was performed in polyethylene and polypropylene tubes to determine whether sufficient expansion could be observed, and satisfactory results were achieved with polypropylene. (96TW-2015-0001) Membership Pending.

  1. Nonicosahedral pathways for capsid expansion

    NASA Astrophysics Data System (ADS)

    Cermelli, Paolo; Indelicato, Giuliana; Twarock, Reidun

    2013-09-01

    For a significant number of viruses a structural transition of the protein container that encapsulates the viral genome forms an important part of the life cycle and is a prerequisite for the particle becoming infectious. Despite many recent efforts the mechanism of this process is still not fully understood, and a complete characterization of the expansion pathways is still lacking. We present here a coarse-grained model that captures the essential features of the expansion process and allows us to investigate the conditions under which a viral capsid becomes unstable. Based on this model we demonstrate that the structural transitions in icosahedral viral capsids are likely to occur through a low-symmetry cascade of local expansion events spreading in a wavelike manner over the capsid surface.

  2. Pauli mechanism for universal expansion

    NASA Astrophysics Data System (ADS)

    Hayes, Robert

    2016-03-01

    By assuming the cosmological principle includes the Pauli exclusion principle (PEP) and that existence occurred post big bang within Planck time and length scales, a model for universal expansion can be argued. All Fermionic matter is forced by the PEP to make a quantum transition to minimally orthogonal states scaling with that predicted for a neutron star (NS). This predicts the minimum inflation time scale to be on the order of 1e-44 s. A coupling of primordial low mass neutrinos to have wavelengths comparable to or greater than the Hubble length is also postulated as a contributor to universal expansion. The model provides a mechanistic explanation for universal expansion using only physics from the standard model. This work supported in part under federal Grant NRC-HQ-84-14-G-0059.

  3. An expansion for neutrino phenomenology

    NASA Astrophysics Data System (ADS)

    Grinstein, Benjamín; Trott, Michael

    2012-09-01

    We develop a formalism for constructing the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix and neutrino masses using an expansion that originates when a sequence of heavy right handed neutrinos are integrated out, assuming a seesaw mechanism for the origin of neutrino masses. The expansion establishes relationships between the structure of the PMNS matrix and the mass differences of neutrinos, and allows symmetry implications for measured deviations from tri-bimaximal form to be studied systematically. Our approach does not depend on choosing the rotation between the weak and mass eigenstates of the charged lepton fields to be diagonal. We comment on using this expansion to examine the symmetry implications of the recent results from the Daya-Bay collaboration reporting the discovery of a non zero value for θ 13, indicating a deviation from tri-bimaximal form, with a significance of 5.2 σ.

  4. Thermal Expansion of Hafnium Carbide

    NASA Technical Reports Server (NTRS)

    Grisaffe, Salvatore J.

    1960-01-01

    Since hafnium carbide (HfC) has a melting point of 7029 deg. F, it may have many high-temperature applications. A literature search uncovered very little information about the properties of HfC, and so a program was initiated at the Lewis Research Center to determine some of the physical properties of this material. This note presents the results of the thermal expansion investigation. The thermal-expansion measurements were made with a Gaertner dilatation interferometer calibrated to an accuracy of +/- 1 deg. F. This device indicates expansion by the movement of fringes produced by the cancellation and reinforcement of fixed wave-length light rays which are reflected from the surfaces of two parallel quartz glass disks. The test specimens which separate these disks are three small cones, each approximately 0.20 in. high.

  5. Demographics of Investigators Involved in OSSA-Funded Research

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan; Konkel, Ronald; Habegger, Jay; Byerly, Radford, Jr.

    1991-01-01

    The birth of the U.S. civil space program and the subsequent, dramatic growth in the ranks of the space science research population occurred in the 1950s and 1960s'. The large, post- Sputnik/ Apollo buildup in space program manpower is now approximately one career-lifetime in the past. It is therefore natural to anticipate that a large fraction of the space program engineers, scientists, and managers who pioneered the early exploration of space are approaching retirement. Such a "retirement wave" bodes both a loss of manpower and, more fundamentally, a loss of experience from the civil-space manpower base. Such losses could play a critical role constraining in NASA's ability to expand or maintain its technical capabilities. If this indeed applies to the NASA space science research population, then the potential for problems is exacerbated by the anticipated growth in flight rates, data volume, and data-set diversity which will accompany the planned expansion in the OSSA science effort during the 1990s and 2000s. The purpose of this study was to describe the OSSA PI/Co-I population and to determine the degree to which the OSSA space science investigator population faces a retirement wave, and to estimate the future population of PIs in the 1990-2010 era. To conduct such a study, we investigated the present demographics of the PI and Co-1 population contained in the NASA/OSSA Announcement of Opportunity (AO) mailing list. PIs represent the "leadership" class of the OSSA scientific researcher population, and Co-Is represent one important, oncoming component of the "replacement" generation. Using the PI population data, we then make projection estimates of the future PI population from 1991 through 2010, under various NASA growth/PI demand scenarios.

  6. Energy efficient perlite expansion process

    SciTech Connect

    Jenkins, K.L.

    1982-08-31

    A thermally efficient process for the expansion of perlite ore is described. The inlet port and burner of a perlite expansion chamber (Preferably a vertical expander) are enclosed such that no ambient air can enter the chamber. Air and fuel are metered to the burner with the amount of air being controlled such that the fuel/air premix contains at least enough air to start and maintain minimum combustion, but not enough to provide stoichiometric combustion. At a point immediately above the burner, additional air is metered into an insulated enclosure surrounding the expansion chamber where it is preheated by the heat passing through the chamber walls. This preheated additional air is then circulated back to the burner where it provides the remainder of the air needed for combustion, normally full combustion. Flow of the burner fuel/air premix and the preheated additional air is controlled so as to maintain a long luminous flame throughout a substantial portion of the expansion chamber and also to form a moving laminar layer of air on the inner surface of the expansion chamber. Preferably the burner is a delayed mixing gas burner which materially aids in the generation of the long luminous flame. The long luminous flame and the laminar layer of air at the chamber wall eliminate hot spots in the expansion chamber, result in relatively low and uniform temperature gradients across the chamber, significantly reduce the amount of fuel consumed per unit of perlite expanded, increase the yield of expanded perlite and prevent the formation of a layer of perlite sinter on the walls of the chamber.

  7. Expansion-based passive ranging

    NASA Technical Reports Server (NTRS)

    Barniv, Yair

    1993-01-01

    A new technique of passive ranging which is based on utilizing the image-plane expansion experienced by every object as its distance from the sensor decreases is described. This technique belongs in the feature/object-based family. The motion and shape of a small window, assumed to be fully contained inside the boundaries of some object, is approximated by an affine transformation. The parameters of the transformation matrix are derived by initially comparing successive images, and progressively increasing the image time separation so as to achieve much larger triangulation baseline than currently possible. Depth is directly derived from the expansion part of the transformation. To a first approximation, image-plane expansion is independent of image-plane location with respect to the focus of expansion (FOE) and of platform maneuvers. Thus, an expansion-based method has the potential of providing a reliable range in the difficult image area around the FOE. In areas far from the FOE the shift parameters of the affine transformation can provide more accurate depth information than the expansion alone, and can thus be used similarly to the way they were used in conjunction with the Inertial Navigation Unit (INU) and Kalman filtering. However, the performance of a shift-based algorithm, when the shifts are derived from the affine transformation, would be much improved compared to current algorithms because the shifts - as well as the other parameters - can be obtained between widely separated images. Thus, the main advantage of this new approach is that, allowing the tracked window to expand and rotate, in addition to moving laterally, enables one to correlate images over a very long time span which, in turn, translates into a large spatial baseline - resulting in a proportionately higher depth accuracy.

  8. Expansion-based passive ranging

    NASA Technical Reports Server (NTRS)

    Barniv, Yair

    1993-01-01

    This paper describes a new technique of passive ranging which is based on utilizing the image-plane expansion experienced by every object as its distance from the sensor decreases. This technique belongs in the feature/object-based family. The motion and shape of a small window, assumed to be fully contained inside the boundaries of some object, is approximated by an affine transformation. The parameters of the transformation matrix are derived by initially comparing successive images, and progressively increasing the image time separation so as to achieve much larger triangulation baseline than currently possible. Depth is directly derived from the expansion part of the transformation. To a first approximation, image-plane expansion is independent of image-plane location with respect to the focus of expansion (FOE) and of platform maneuvers. Thus, an expansion-based method has the potential of providing a reliable range in the difficult image area around the FOE. In areas far from the FOE the shift parameters of the affine transformation can provide more accurate depth information than the expansion alone, and can thus be used similarly to the way they have been used in conjunction with the Inertial Navigation Unit (INU) and Kalman filtering. However, the performance of a shift-based algorithm, when the shifts are derived from the affine transformation, would be much improved compared to current algorithms because the shifts--as well as the other parameters--can be obtained between widely separated images. Thus, the main advantage of this new approach is that, allowing the tracked window to expand and rotate, in addition to moving laterally, enables one to correlate images over a very long time span which, in turn, translates into a large spatial baseline resulting in a proportionately higher depth accuracy.

  9. Relativistic effects on plasma expansion

    SciTech Connect

    Benkhelifa, El-Amine; Djebli, Mourad

    2014-07-15

    The expansion of electron-ion plasma is studied through a fully relativistic multi-fluids plasma model which includes thermal pressure, ambipolar electrostatic potential, and internal energy conversion. Numerical investigation, based on quasi-neutral assumption, is performed for three different regimes: nonrelativistic, weakly relativistic, and relativistic. Ions' front in weakly relativistic regime exhibits spiky structure associated with a break-down of quasi-neutrality at the expanding front. In the relativistic regime, ion velocity is found to reach a saturation limit which occurs at earlier stages of the expansion. This limit is enhanced by higher electron velocity.

  10. Y chromosome diversity, human expansion, drift, and cultural evolution

    PubMed Central

    Chiaroni, Jacques; Underhill, Peter A.; Cavalli-Sforza, Luca L.

    2009-01-01

    The relative importance of the roles of adaptation and chance in determining genetic diversity and evolution has received attention in the last 50 years, but our understanding is still incomplete. All statements about the relative effects of evolutionary factors, especially drift, need confirmation by strong demographic observations, some of which are easier to obtain in a species like ours. Earlier quantitative studies on a variety of data have shown that the amount of genetic differentiation in living human populations indicates that the role of positive (or directional) selection is modest. We observe geographic peculiarities with some Y chromosome mutants, most probably due to a drift-related phenomenon called the surfing effect. We also compare the overall genetic diversity in Y chromosome DNA data with that of other chromosomes and their expectations under drift and natural selection, as well as the rate of fall of diversity within populations known as the serial founder effect during the recent “Out of Africa” expansion of modern humans to the whole world. All these observations are difficult to explain without accepting a major relative role for drift in the course of human expansions. The increasing role of human creativity and the fast diffusion of inventions seem to have favored cultural solutions for many of the problems encountered in the expansion. We suggest that cultural evolution has been subrogating biologic evolution in providing natural selection advantages and reducing our dependence on genetic mutations, especially in the last phase of transition from food collection to food production. PMID:19920170

  11. Demographic and occupational correlates of workaholism.

    PubMed

    Taris, Toon W; Van Beek, Ilona; Schaufeli, Wilmar B

    2012-04-01

    Drawing on a convenience sample of 9,160 Dutch employees, the present study examined whether commonly held ideas about the associations between demographic, professional, and occupational characteristics and workaholism would be observed. For example, it is sometimes assumed that managers are more likely to display workaholic tendencies than others. Analysis of variance was used to relate workaholism scores (measured as the combination of working excessively and working compulsively) to participant age, sex, employment status (self-employed or not), profession, and occupational sector. Relatively high average scores on workaholism were obtained by workers in the agriculture, construction, communication, consultancy, and commerce/trade sectors, as well as managers and higher professionals. Low scores were found for those in the public administration and services industry sectors, and for nurses, social workers, and paramedics. The other characteristics were not or only weakly related to workaholism. PMID:22662409

  12. Demographic variation in nutrition knowledge in England

    PubMed Central

    Parmenter, K.; Waller, J.; Wardle, J.

    2000-01-01

    This paper describes a nutrition knowledge survey carried out on a cross-section of the adult population of England (n = 1040), looking at knowledge relating to current dietary recommendations, sources of nutrients, healthy food choices and diet–disease links. Serious gaps in knowledge about even the basic recommendations were discovered, and there was much confusion over the relationship between diet and disease. Significant differences in knowledge between socio-demographic groups were found, with men having poorer knowledge than women, and knowledge declining with lower educational level and socio-economic status. Possible reasons for these differences and implications for public education campaigns and socio-economic inequalities in health are discussed. PMID:10751375

  13. 3D face analysis for demographic biometrics

    SciTech Connect

    Tokola, Ryan A; Mikkilineni, Aravind K; Boehnen, Chris Bensing

    2015-01-01

    Despite being increasingly easy to acquire, 3D data is rarely used for face-based biometrics applications beyond identification. Recent work in image-based demographic biometrics has enjoyed much success, but these approaches suffer from the well-known limitations of 2D representations, particularly variations in illumination, texture, and pose, as well as a fundamental inability to describe 3D shape. This paper shows that simple 3D shape features in a face-based coordinate system are capable of representing many biometric attributes without problem-specific models or specialized domain knowledge. The same feature vector achieves impressive results for problems as diverse as age estimation, gender classification, and race classification.

  14. Demographic group differences in adolescents' time attitudes.

    PubMed

    Andretta, James R; Worrell, Frank C; Mello, Zena R; Dixson, Dante D; Baik, Sharon H

    2013-04-01

    In the present study, we examined demographic differences in time attitudes in a sample of 293 adolescents. Time attitudes were measured using the Adolescent Time Attitude Scale (Mello & Worrell, 2007; Worrell, Mello, & Buhl, 2011), which assesses positive and negative attitudes toward the past, the present, and the future. Generally, African Americans and Asian Americans reported higher scores for negative time attitudes and lower scores for positive time attitudes than European Americans and Latinos, with medium sizes. Adolescents in the low socioeconomic status group reported a less favorable evaluation of their past than middle and high SES peers, but there were no meaningful differences in time attitudes by gender. Findings indicate that middle SES adolescents, high school juniors and seniors, Latinos, and European Americans had higher representation in positive time attitude clusters (i.e., Positives and Balanced) than high SES adolescents, high school freshmen and sophomores, and African Americans. PMID:23274039

  15. Earliest recollections of childhood: a demographic analysis.

    PubMed

    Mullen, M K

    1994-07-01

    A theory has recently been advanced which proposes that the development autobiographical recollection is shaped by a child's participation in discussions of events with adults (e.g. Nelson, 1988; Snow, 1990). A logical prediction of the theory is that demographic factors related to the nature of linguistic environments might be associated with differences in the development of autobiographical recollection. Four questionnaire studies that test this prediction are presented. The results, on a total of 768 subjects, show that the age of earliest memory increases across birth order, is slightly earlier for females than for males, and is earlier for Caucasians than for Asians. These findings are discussed in light of previous research showing that parents interact and talk more with first-borns and with girls, and in light of differences between Western and Asian cultures in socialization goals and the significance of autobiography in the development of self-concept. PMID:7924199

  16. 48 CFR 570.403 - Expansion requests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 4 2012-10-01 2012-10-01 false Expansion requests. 570... Continued Space Requirements 570.403 Expansion requests. (a) If the expansion space is in the general scope... justification under FAR 6.3. (b) If the expansion space needed is outside the general scope of the lease,...

  17. 18 CFR 154.309 - Incremental expansions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Incremental expansions... Changes § 154.309 Incremental expansions. (a) For every expansion for which incremental rates are charged... costs and revenues associated with the expansion, until the Commission authorizes the costs of...

  18. 18 CFR 154.309 - Incremental expansions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Incremental expansions... Changes § 154.309 Incremental expansions. (a) For every expansion for which incremental rates are charged... costs and revenues associated with the expansion, until the Commission authorizes the costs of...

  19. 18 CFR 154.309 - Incremental expansions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Incremental expansions... Changes § 154.309 Incremental expansions. (a) For every expansion for which incremental rates are charged... costs and revenues associated with the expansion, until the Commission authorizes the costs of...

  20. 18 CFR 154.309 - Incremental expansions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Incremental expansions... Changes § 154.309 Incremental expansions. (a) For every expansion for which incremental rates are charged... costs and revenues associated with the expansion, until the Commission authorizes the costs of...

  1. 48 CFR 570.403 - Expansion requests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 4 2013-10-01 2013-10-01 false Expansion requests. 570... Continued Space Requirements 570.403 Expansion requests. (a) If the expansion space is in the general scope... justification under FAR 6.3. (b) If the expansion space needed is outside the general scope of the lease,...

  2. 48 CFR 570.403 - Expansion requests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false Expansion requests. 570... Continued Space Requirements 570.403 Expansion requests. (a) If the expansion space is in the general scope... justification under FAR 6.3. (b) If the expansion space needed is outside the general scope of the lease,...

  3. 48 CFR 570.403 - Expansion requests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Expansion requests. 570... Continued Space Requirements 570.403 Expansion requests. (a) If the expansion space is in the general scope... FAR 6.3. (b) If the expansion space needed is outside the general scope of the lease,...

  4. 18 CFR 154.309 - Incremental expansions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Incremental expansions... Changes § 154.309 Incremental expansions. (a) For every expansion for which incremental rates are charged... costs and revenues associated with the expansion, until the Commission authorizes the costs of...

  5. 48 CFR 570.403 - Expansion requests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false Expansion requests. 570... Continued Space Requirements 570.403 Expansion requests. (a) If the expansion space is in the general scope... justification under FAR 6.3. (b) If the expansion space needed is outside the general scope of the lease,...

  6. The Thermal Expansion Of Feldspars

    NASA Astrophysics Data System (ADS)

    Hovis, G. L.; Medford, A.; Conlon, M.

    2009-12-01

    Hovis and others (1) investigated the thermal expansion of natural and synthetic AlSi3 feldspars and demonstrated that the coefficient of thermal expansion (α) decreases significantly, and linearly, with increasing room-temperature volume (VRT). In all such feldspars, therefore, chemical expansion limits thermal expansion. The scope of this work now has been broadened to include plagioclase and Ba-K feldspar crystalline solutions. X-ray powder diffraction data have been collected between room temperature and 925 °C on six plagioclase specimens ranging in composition from anorthite to oligoclase. When combined with thermal expansion data for albite (2,3,4) a steep linear trend of α as a function of VRT emerges, reflecting how small changes in composition dramatically affect expansion behavior. The thermal expansion data for five synthetic Ba-K feldspars ranging in composition from 20 to 100 mole percent celsian, combined with data for pure K-feldspar (3,4), show α-VRT relationships similar in nature to the plagioclase series, but with a slope and intercept different from the latter. Taken as a group all Al2Si2 feldspars, including anorthite and celsian from the present study along with Sr- (5) and Pb-feldspar (6) from other workers, show very limited thermal expansion that, unlike AlSi3 feldspars, has little dependence on the divalent-ion (or M-) site occupant. This apparently is due to the necessitated alternation of Al and Si in the tetrahedral sites of these minerals (7), which in turn locks the tetrahedral framework and makes the M-site occupant nearly irrelevant to expansion behavior. Indeed, in feldspar series with coupled chemical substitution it is the change away from a 1:1 Al:Si ratio that gives feldspars greater freedom to expand. Overall, the relationships among α, chemical composition, and room-temperature volume provide useful predictive tools for estimating feldspar thermal expansion and give insight into the controls of expansion behavior in

  7. Population genetic structure and demographic history of Atrina pectinata based on mitochondrial DNA and microsatellite markers.

    PubMed

    Xue, Dong-Xiu; Wang, Hai-Yan; Zhang, Tao; Liu, Jin-Xian

    2014-01-01

    The pen shell, Atrina pectinata, is one of the commercial bivalves in East Asia and thought to be recently affected by anthropogenic pressure (habitat destruction and/or fishing pressure). Information on its population genetic structure is crucial for the conservation of A. pectinata. Considering its long pelagic larval duration and iteroparity with high fecundity, the genetic structure for A. pectinata could be expected to be weak at a fine scale. However, the unusual oceanography in the coasts of China and Korea suggests potential for restricted dispersal of pelagic larvae and geographical differentiation. In addition, environmental changes associated with Pleistocene sea level fluctuations on the East China Sea continental shelf may also have strongly influenced historical population demography and genetic diversity of marine organisms. Here, partial sequences of the mitochondrial Cytochrome c oxidase subunit I (COI) gene and seven microsatellite loci were used to estimate population genetic structure and demographic history of seven samples from Northern China coast and one sample from North Korea coast. Despite high levels of genetic diversity within samples, there was no genetic differentiation among samples from Northern China coast and low but significant genetic differentiation between some of the Chinese samples and the North Korean sample. A late Pleistocene population expansion, probably after the Last Glacial Maximum, was also demonstrated for A. pectinata samples. No recent genetic bottleneck was detected in any of the eight samples. We concluded that both historical recolonization (through population range expansion and demographic expansion in the late Pleistocene) and current gene flow (through larval dispersal) were responsible for the weak level of genetic structure detected in A. pectinata. PMID:24789175

  8. Potential (mis)match?: Marriage Markets amidst Socio-Demographic Change in India, 2005–2050

    PubMed Central

    Kashyap, Ridhi; Esteve, Albert; García-Román, Joan

    2015-01-01

    We explore the impact of socio-demographic change on marriage patterns in India by examining the hypothetical consequences of applying three sets of marriage pairing propensities – contemporary patterns by age, by age and education, and changing propensities that allow for greater educational homogamy and reduced educational asymmetries – to future population projections. Future population prospects for India indicate three trends that will impact marriage patterns: i) female-deficit in sex ratios at birth; ii) declining birth cohort size; iii) female educational expansion. Existing literature posits declining marriage rates for men arising from skewed sex ratios at birth (SRB) in India’s population. In addition to skewed SRBs, India’s population will experience female educational expansion in the coming decades. Female educational expansion and its impact on marriage patterns must be jointly considered with demographic changes, given educational differentials and asymmetries in union formation that exist in India, as across much of the world. We systematize contemporary pairing propensities using data from the 2005–2006 Indian National Family Health Survey and the 2004 Socio-Economic Survey and apply these and the third set of changing propensities to IIASA/VID multi-state population projections by educational attainment using an iterative longitudinal projection procedure. If today’s age patterns of marriage are viewed against age-sex population composition until 2050, men experience declining marriage prevalence. However, when education is included, women, particularly those with higher education experience a more salient rise in non-marriage. Significant changes in pairing patterns towards greater levels of educational homogamy and gender symmetry can counteract a marked rise in non-marriage. PMID:25604846

  9. Population Genetic Structure and Demographic History of Atrina pectinata Based on Mitochondrial DNA and Microsatellite Markers

    PubMed Central

    Xue, Dong-Xiu; Wang, Hai-Yan; Zhang, Tao; Liu, Jin-Xian

    2014-01-01

    The pen shell, Atrina pectinata, is one of the commercial bivalves in East Asia and thought to be recently affected by anthropogenic pressure (habitat destruction and/or fishing pressure). Information on its population genetic structure is crucial for the conservation of A. pectinata. Considering its long pelagic larval duration and iteroparity with high fecundity, the genetic structure for A. pectinata could be expected to be weak at a fine scale. However, the unusual oceanography in the coasts of China and Korea suggests potential for restricted dispersal of pelagic larvae and geographical differentiation. In addition, environmental changes associated with Pleistocene sea level fluctuations on the East China Sea continental shelf may also have strongly influenced historical population demography and genetic diversity of marine organisms. Here, partial sequences of the mitochondrial Cytochrome c oxidase subunit I (COI) gene and seven microsatellite loci were used to estimate population genetic structure and demographic history of seven samples from Northern China coast and one sample from North Korea coast. Despite high levels of genetic diversity within samples, there was no genetic differentiation among samples from Northern China coast and low but significant genetic differentiation between some of the Chinese samples and the North Korean sample. A late Pleistocene population expansion, probably after the Last Glacial Maximum, was also demonstrated for A. pectinata samples. No recent genetic bottleneck was detected in any of the eight samples. We concluded that both historical recolonization (through population range expansion and demographic expansion in the late Pleistocene) and current gene flow (through larval dispersal) were responsible for the weak level of genetic structure detected in A. pectinata. PMID:24789175

  10. Clamshell Thermal-Expansion Bellows

    NASA Technical Reports Server (NTRS)

    Fesmire, J.; Moore, W. I.; Dipasquale, S. D.

    1993-01-01

    Improved bellows serves as thermal-expansion joint in vacuum-jacketed cyrogenic piping system. Made of Hastelloy C-22 and fabricated in field by welding two clam-shell-like half bellows. No protective paint or maintenance needed. Design modified to fit most thin-wall bellows.