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Sample records for geographical parthenogenesis general

  1. Geographic parthenogenesis and plant-enemy interactions in the common dandelion.

    PubMed

    Verhoeven, Koen J F; Biere, Arjen

    2013-01-28

    Many species with sexual and asexual variants show a pattern of geographic parthenogenesis where asexuals have broader and higher-latitude distribution than sexuals. Because sexual reproduction is often considered a costly evolutionary strategy that is advantageous in the face of selection by coevolving pests and pathogens, one possible explanation for geographic parthenogenesis is that populations at higher latitudes are exposed to fewer pests and pathogens. We tested this hypothesis in the common dandelion (Taraxacum officinale), a species with well-established geographic parthenogenesis, by screening prevalence and effects of several specialized pests and pathogens in natural dandelion populations. We did a population survey of 18 dandelion populations along a geographic transect that ranged from the area where sexual and asexual dandelions co-occur northward into the area where only asexuals occur. In addition we used four southern and four northern populations in a 8x8 cross-inoculation greenhouse experiment in which plants were exposed experimentally to each other's natural field soil microbial communities. The cross-inoculation experiment indicated a higher pathogenicity of soil microbial communities from the southern, mostly sexual, populations compared to soil microbial communities from the northern asexual populations. Northern dandelion populations also showed reduced infestation by a specialized seed-eating weevil. A similar trend of reduced rust fungus infection in northern populations was observed but this trend was not statistically significant. The prevalence of pests and pathogens decreased along the south-to-north axis of geographic parthenogenesis. This highlights the potential of biotic interactions in shaping patterns of geographic parthenogenesis.

  2. Geographic parthenogenesis and plant-enemy interactions in the common dandelion

    PubMed Central

    2013-01-01

    Background Many species with sexual and asexual variants show a pattern of geographic parthenogenesis where asexuals have broader and higher-latitude distribution than sexuals. Because sexual reproduction is often considered a costly evolutionary strategy that is advantageous in the face of selection by coevolving pests and pathogens, one possible explanation for geographic parthenogenesis is that populations at higher latitudes are exposed to fewer pests and pathogens. We tested this hypothesis in the common dandelion (Taraxacum officinale), a species with well-established geographic parthenogenesis, by screening prevalence and effects of several specialized pests and pathogens in natural dandelion populations. Results We did a population survey of 18 dandelion populations along a geographic transect that ranged from the area where sexual and asexual dandelions co-occur northward into the area where only asexuals occur. In addition we used four southern and four northern populations in a 8x8 cross-inoculation greenhouse experiment in which plants were exposed experimentally to each other’s natural field soil microbial communities. The cross-inoculation experiment indicated a higher pathogenicity of soil microbial communities from the southern, mostly sexual, populations compared to soil microbial communities from the northern asexual populations. Northern dandelion populations also showed reduced infestation by a specialized seed-eating weevil. A similar trend of reduced rust fungus infection in northern populations was observed but this trend was not statistically significant. Conclusions The prevalence of pests and pathogens decreased along the south-to-north axis of geographic parthenogenesis. This highlights the potential of biotic interactions in shaping patterns of geographic parthenogenesis. PMID:23356700

  3. Geographic parthenogenesis in a consumer-resource model for sexual reproduction.

    PubMed

    Song, Yixian; Scheu, Stefan; Drossel, Barbara

    2011-03-21

    The phenomenon of geographic parthenogenesis is closely tied to the question of why sexual reproduction is the dominant mode of reproduction in animals and plants. Geographic parthenogenesis describes the fact that many species reproduce asexually at the boundaries of their range. We present a mathematical model that derives the dominance of sexuals at the center and the dominance of asexuals at the boundary of a species' range from exactly the same mechanism. Our model is based on a set of resources that regrow slowly and that can be consumed only by those individuals that have a suitable genotype. Genotype is implemented by a multilocus model with two alleles at each locus, and with free recombination during production of sexual offspring. The model is tailored to seasonal species with intermittent mixis and low survival of offspring, such as Daphnia and aphids. Several patches of resources are arranged in a row, with a gradient of those parameters that typically vary through the range of species. By letting sexually and asexually reproducing populations compete, we obtain the typical patterns of geographic parthenogenesis. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Cytotype stability, facultative apomixis and geographical parthenogenesis in Ranunculus kuepferi (Ranunculaceae).

    PubMed

    Cosendai, Anne-Caroline; Hörandl, Elvira

    2010-03-01

    Asexual organisms are more widespread in previously glaciated areas than their sexual relatives ('geographical parthenogenesis'). In plants, this pattern is probably dependent on reproductive isolation and stability of cytotypes within their respective distribution areas. Both partial apomixis and introgressive hybridization potentially destabilize the spatial separation of sexual and apomictic populations. The wide distribution of apomicts may be further enhanced by uniparental reproduction which is advantageous for colonization. These factors are studied in the alpine species Ranunculus kuepferi. Geographical distribution, diversity and mode of reproduction of cytotypes were assessed using flow cytometry and flow cytometric seed screening on samples from 59 natural populations of Ranunculus kuepferi. Seed set of cytotypes was compared in the wild. Diploid sexuals are confined to the south-western parts of the Alps, while tetraploid apomicts dominate in previously glaciated and in geographically isolated areas despite a significantly lower fertility. Other cytotypes (3x, 5x and 6x) occur mainly in the sympatric zone, but without establishing populations. The tetraploids are predominantly apomictic, but also show a partial apomixis via an uncoupling of apomeiosis and parthenogenesis in the seed material. Both pseudogamy and autonomous endosperm formation are observed which may enhance uniparental reproduction. Diploids occupy a glacial relic area and resist introgression of apomixis, probably because of a significantly higher seed set. Among the polyploids, only apomictic tetraploids form stable populations; the other cytotypes arising from partial apomixis fail to establish, probably because of minority cytotype disadvantages. Tetraploid apomicts colonize previously devastated and also distant areas via long-distance dispersal, confirming Baker's law of an advantage of uniparental reproduction. It is concluded that stability of cytotypes and of modes of

  5. Population genomics and geographical parthenogenesis in Japanese harvestmen (Opiliones, Sclerosomatidae, Leiobunum).

    PubMed

    Burns, Mercedes; Hedin, Marshal; Tsurusaki, Nobuo

    2018-01-01

    Naturally occurring population variation in reproductive mode presents an opportunity for researchers to test hypotheses regarding the evolution of sex. Asexual reproduction frequently assumes a geographical pattern, in which parthenogenesis-dominated populations are more broadly dispersed than their sexual conspecifics. We evaluate the geographical distribution of genomic signatures associated with parthenogenesis using nuclear and mitochondrial DNA sequence data from two Japanese harvestman sister taxa, Leiobunum manubriatum and Leiobunum globosum . Asexual reproduction is putatively facultative in these species, and female-biased localities are common in habitat margins. Past karyotypic and current cytometric work indicates L. globosum is entirely tetraploid, while L. manubriatum may be either diploid or tetraploid. We estimated species phylogeny, genetic differentiation, diversity, and mitonuclear discordance in females collected across the species range in order to identify range expansion toward marginal habitat, potential for hybrid origin, and persistence of asexual lineages. Our results point to northward expansion of a tetraploid ancestor of L. manubriatum and L. globosum , coupled with support for greater male gene flow in southern L. manubriatum localities. Specimens from localities in the Tohoku and Hokkaido regions were indistinct, particularly those of L. globosum , potentially due to little mitochondrial differentiation or haplotypic variation. Although L. manubriatum overlaps with L. globosum across its entire range, L. globosum was reconstructed as monophyletic with strong support using mtDNA, and marginal support with nuclear loci. Ultimately, we find evidence for continued sexual reproduction in both species and describe opportunities to clarify the rate and mechanism of parthenogenesis.

  6. Cytotype stability, facultative apomixis and geographical parthenogenesis in Ranunculus kuepferi (Ranunculaceae)

    PubMed Central

    Cosendai, Anne-Caroline; Hörandl, Elvira

    2010-01-01

    Background and Aims Asexual organisms are more widespread in previously glaciated areas than their sexual relatives (‘geographical parthenogenesis’). In plants, this pattern is probably dependent on reproductive isolation and stability of cytotypes within their respective distribution areas. Both partial apomixis and introgressive hybridization potentially destabilize the spatial separation of sexual and apomictic populations. The wide distribution of apomicts may be further enhanced by uniparental reproduction which is advantageous for colonization. These factors are studied in the alpine species Ranunculus kuepferi. Methods Geographical distribution, diversity and mode of reproduction of cytotypes were assessed using flow cytometry and flow cytometric seed screening on samples from 59 natural populations of Ranunculus kuepferi. Seed set of cytotypes was compared in the wild. Key Results Diploid sexuals are confined to the south-western parts of the Alps, while tetraploid apomicts dominate in previously glaciated and in geographically isolated areas despite a significantly lower fertility. Other cytotypes (3x, 5x and 6x) occur mainly in the sympatric zone, but without establishing populations. The tetraploids are predominantly apomictic, but also show a partial apomixis via an uncoupling of apomeiosis and parthenogenesis in the seed material. Both pseudogamy and autonomous endosperm formation are observed which may enhance uniparental reproduction. Conclusions Diploids occupy a glacial relic area and resist introgression of apomixis, probably because of a significantly higher seed set. Among the polyploids, only apomictic tetraploids form stable populations; the other cytotypes arising from partial apomixis fail to establish, probably because of minority cytotype disadvantages. Tetraploid apomicts colonize previously devastated and also distant areas via long-distance dispersal, confirming Baker's law of an advantage of uniparental reproduction. It is

  7. Geographical parthenogenesis and population genetic structure in the alpine species Ranunculus kuepferi (Ranunculaceae).

    PubMed

    Cosendai, A-C; Wagner, J; Ladinig, U; Rosche, C; Hörandl, E

    2013-06-01

    Geographical parthenogenesis describes the enigmatic phenomenon that asexual organisms have larger distribution areas than their sexual relatives, especially in previously glaciated areas. Classical models suggest temporary advantages to asexuality in colonization scenarios because of uniparental reproduction and clonality. We analyzed population genetic structure and self-fertility of the plant species Ranunculus kuepferi on 59 populations from the whole distribution area (European Alps, Apennines and Corsica). Amplified fragment length polymorphisms (AFLPs) and five microsatellite loci revealed individual genotypes for all populations and mostly insignificant differences between diploid sexuals and tetraploid apomicts in all measures of genetic diversity. Low frequencies of private AFLP fragments/simple sequence repeat alleles, and character incompatibility analyses suggest that facultative recombination explains best the unexpectedly high genotypic diversity of apomicts. STRUCTURE analyses using AFLPs revealed a higher number of partitions and a stronger geographical subdivision for diploids than for tetraploids, which contradicts expectations of standard gene flow models, but indicates a reduction of genetic structure in asexuals. Apomictic populations exhibited high admixture near the sexual area, but appeared rather uniform in remote areas. Bagging experiments and analyses of pollen tube growth confirmed self-fertility for pollen-dependent apomicts, but self-sterility for diploid sexuals. Facultative apomixis combines advantages of both modes of reproduction: uniparental reproduction allows for rapid colonization of remote areas, whereas facultative sexuality and polyploidy maintains genetic diversity within apomictic populations. The density dependence of outcrossing limits range expansions of sexual populations.

  8. Geographical parthenogenesis and population genetic structure in the alpine species Ranunculus kuepferi (Ranunculaceae)

    PubMed Central

    Cosendai, A-C; Wagner, J; Ladinig, U; Rosche, C; Hörandl, E

    2013-01-01

    Geographical parthenogenesis describes the enigmatic phenomenon that asexual organisms have larger distribution areas than their sexual relatives, especially in previously glaciated areas. Classical models suggest temporary advantages to asexuality in colonization scenarios because of uniparental reproduction and clonality. We analyzed population genetic structure and self-fertility of the plant species Ranunculus kuepferi on 59 populations from the whole distribution area (European Alps, Apennines and Corsica). Amplified fragment length polymorphisms (AFLPs) and five microsatellite loci revealed individual genotypes for all populations and mostly insignificant differences between diploid sexuals and tetraploid apomicts in all measures of genetic diversity. Low frequencies of private AFLP fragments/simple sequence repeat alleles, and character incompatibility analyses suggest that facultative recombination explains best the unexpectedly high genotypic diversity of apomicts. STRUCTURE analyses using AFLPs revealed a higher number of partitions and a stronger geographical subdivision for diploids than for tetraploids, which contradicts expectations of standard gene flow models, but indicates a reduction of genetic structure in asexuals. Apomictic populations exhibited high admixture near the sexual area, but appeared rather uniform in remote areas. Bagging experiments and analyses of pollen tube growth confirmed self-fertility for pollen-dependent apomicts, but self-sterility for diploid sexuals. Facultative apomixis combines advantages of both modes of reproduction: uniparental reproduction allows for rapid colonization of remote areas, whereas facultative sexuality and polyploidy maintains genetic diversity within apomictic populations. The density dependence of outcrossing limits range expansions of sexual populations. PMID:23403961

  9. Reconstructing geographical parthenogenesis: effects of niche differentiation and reproductive mode on Holocene range expansion of an alpine plant.

    PubMed

    Kirchheimer, Bernhard; Wessely, Johannes; Gattringer, Andreas; Hülber, Karl; Moser, Dietmar; Schinkel, Christoph C F; Appelhans, Marc; Klatt, Simone; Caccianiga, Marco; Dellinger, Agnes; Guisan, Antoine; Kuttner, Michael; Lenoir, Jonathan; Maiorano, Luigi; Nieto-Lugilde, Diego; Plutzar, Christoph; Svenning, Jens-Christian; Willner, Wolfgang; Hörandl, Elvira; Dullinger, Stefan

    2018-03-01

    Asexual taxa often have larger ranges than their sexual progenitors, particularly in areas affected by Pleistocene glaciations. The reasons given for this 'geographical parthenogenesis' are contentious, with expansion of the ecological niche or colonisation advantages of uniparental reproduction assumed most important in case of plants. Here, we parameterized a spread model for the alpine buttercup Ranunculus kuepferi and reconstructed the joint Holocene range expansion of its sexual and apomictic cytotype across the European Alps under different simulation settings. We found that, rather than niche broadening or a higher migration rate, a shift of the apomict's niche towards colder conditions per se was crucial as it facilitated overcoming of topographical barriers, a factor likely relevant for many alpine apomicts. More generally, our simulations suggest potentially strong interacting effects of niche differentiation and reproductive modes on range formation of related sexual and asexual taxa arising from their differential sensitivity to minority cytotype disadvantage. © 2018 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.

  10. Waves of parthenogenesis in the desert: evidence for the parallel loss of sex in a grasshopper and a gecko from Australia.

    PubMed

    Kearney, Michael; Blacket, Mark J; Strasburg, Jared L; Moritz, Craig

    2006-06-01

    The rarity of parthenogenesis, reproduction without sex, is a major evolutionary puzzle. To understand why sexual genetic systems are so successful in nature, we must understand why parthenogenesis sometimes evolves and persists. Here we use DNA sequence data to test for similarities in the tempo and mode of the evolution of parthenogenesis in a grasshopper and a lizard from the Australian desert. We find spectacular congruence between genetic and geographic patterns of parthenogenesis in these distantly related organisms. In each species, parthenogenesis evolved twice and appears to have expanded in parallel waves across the desert, suggesting a highly general selective force against sex.

  11. Effects of parthenogenesis and geographic isolation on female sexual traits in a parasitoid wasp.

    PubMed

    Kraaijeveld, Ken; Franco, Padu; Reumer, Barbara M; van Alphen, Jacques J M

    2009-12-01

    Population divergence in sexual traits is affected by different selection pressures, depending on the mode of reproduction. In allopatric sexual populations, aspects of sexual behavior may diverge due to sexual selection. In parthenogenetic populations, loss-of-function mutations in genes involved in sexual functionality may be selectively neutral or favored by selection. We assess to what extent these processes have contributed to divergence in female sexual traits in the parasitoid wasp Leptopilina clavipes in which some populations are infected with parthenogenesis-inducing Wolbachia bacteria. We find evidence consistent with both hypotheses. Both arrhenotokous males and males derived from thelytokous strains preferred to court females from their own population. This suggests that these populations had already evolved population-specific mating preferences when the latter became parthenogenetic. Thelytokous females did not store sperm efficiently and fertilized very few of their eggs. The nonfertility of thelytokous females was due to mutations in the wasp genome, which must be an effect of mutation accumulation under thelytoky. Divergence in female sexual traits of these two allopatric populations has thus been molded by different forces: independent male/female coevolution while both populations were still sexual, followed by female-only evolution after one population switched to parthenogenesis.

  12. Cytogenetic and molecular evidence suggest multiple origins and geographical parthenogenesis in Nothoscordum gracile (Alliaceae).

    PubMed

    Souza, Luiz Gustavo Rodrigues; Crosa, Orfeo; Speranza, Pablo; Guerra, Marcelo

    2012-04-01

    Nothoscordum gracile is an apomitic tetraploid widely distributed throughout the Americas and naturalized in many temperate regions of other continents. It has been suggested to form a species complex with sexual and apomictic N. nudicaule and N. macrostemon. Tetraploids of these species also share a structurally heterozygous chromosome complement 2n = 19 (13M + 6A). In this work, the origin of N. gracile and its relationships with its related species was investigated based on cytological and molecular data. Cytogenetic analyses were based on meiotic behaviour, CMA bands, localization of 5S and 45S rDNA sites, and genomic in situ hybridization (GISH). Nuclear ITS and plastidial trnL-trnF sequences were also obtained for most individuals. Proximal CMA bands were observed in the long arms of all acrocentrics of 2x and 4x N. macrostemon but not in diploid and some tetraploid cytotypes of N. nudicaule. Samples of N. gracile showed a variable number of CMA bands in the long arms of acrocentrics. Analysis of ITS sequences, dot-blot, GISH, and 5S and 45S rDNA sites, revealed no differentiation among the three species. The trnL-trnF cpDNA fragment showed variation with a trend to geographical structuring irrespective of morphospecies and fully congruent with karyotype variation. The 2n = 19 karyotype was probably formed by a centric fusion event occurring in N. nudicaule and later transmitted to tetraploid cytotypes of N. macrostemon. Diploids of N. nudicaule and N. macrostemon appeared as consistent recently diverged species, whereas tetraploid apomicts seem to constitute an assemblage of polyploid hybrids originating from multiple independent hybridization events between them, part of which are morphologically recognizable as N. gracile.

  13. The persistence of facultative parthenogenesis in Drosophila albomicans.

    PubMed

    Chang, Chia-chen; Ting, Chau-Ti; Chang, Ching-Ho; Fang, Shu; Chang, Hwei-yu

    2014-01-01

    Parthenogenesis has evolved independently in more than 10 Drosophila species. Most cases are tychoparthenogenesis, which is occasional or accidental parthenogenesis in normally bisexual species with a low hatching rate of eggs produced by virgin females; this form is presumed to be an early stage of parthenogenesis. To address how parthenogenesis and sexual reproduction coexist in Drosophila populations, we investigated several reproductive traits, including the fertility, parthenogenetic capability, diploidization mechanisms, and mating propensity of parthenogenetic D. albomicans. The fertility of mated parthenogenetic females was significantly higher than that of virgin females. The mated females could still produce parthenogenetic offspring but predominantly produced offspring by sexual reproduction. Both mated parthenogenetic females and their parthenogenetic-sexual descendants were capable of parthenogenesis. The alleles responsible for parthenogenesis can be propagated through both parthenogenesis and sexual reproduction. As diploidy is restored predominantly by gamete duplication, heterozygosity would be very low in parthenogenetic individuals. Hence, genetic variation in parthenogenetic genomes would result from sexual reproduction. The mating propensity of females after more than 20 years of isolation from males was decreased. If mutations reducing mating propensities could occur under male-limited conditions in natural populations, decreased mating propensity might accelerate tychoparthenogenesis through a positive feedback mechanism. This process provides an opportunity for the evolution of obligate parthenogenesis. Therefore, the persistence of facultative parthenogenesis may be an adaptive reproductive strategy in Drosophila when a few founders colonize a new niche or when small populations are distributed at the edge of a species' range, consistent with models of geographical parthenogenesis.

  14. The Persistence of Facultative Parthenogenesis in Drosophila albomicans

    PubMed Central

    Chang, Ching-Ho; Fang, Shu; Chang, Hwei-yu

    2014-01-01

    Parthenogenesis has evolved independently in more than 10 Drosophila species. Most cases are tychoparthenogenesis, which is occasional or accidental parthenogenesis in normally bisexual species with a low hatching rate of eggs produced by virgin females; this form is presumed to be an early stage of parthenogenesis. To address how parthenogenesis and sexual reproduction coexist in Drosophila populations, we investigated several reproductive traits, including the fertility, parthenogenetic capability, diploidization mechanisms, and mating propensity of parthenogenetic D. albomicans. The fertility of mated parthenogenetic females was significantly higher than that of virgin females. The mated females could still produce parthenogenetic offspring but predominantly produced offspring by sexual reproduction. Both mated parthenogenetic females and their parthenogenetic-sexual descendants were capable of parthenogenesis. The alleles responsible for parthenogenesis can be propagated through both parthenogenesis and sexual reproduction. As diploidy is restored predominantly by gamete duplication, heterozygosity would be very low in parthenogenetic individuals. Hence, genetic variation in parthenogenetic genomes would result from sexual reproduction. The mating propensity of females after more than 20 years of isolation from males was decreased. If mutations reducing mating propensities could occur under male-limited conditions in natural populations, decreased mating propensity might accelerate tychoparthenogenesis through a positive feedback mechanism. This process provides an opportunity for the evolution of obligate parthenogenesis. Therefore, the persistence of facultative parthenogenesis may be an adaptive reproductive strategy in Drosophila when a few founders colonize a new niche or when small populations are distributed at the edge of a species' range, consistent with models of geographical parthenogenesis. PMID:25415200

  15. Phylogeography and modes of reproduction in diploid and tetraploid halophytes of Limonium species (Plumbaginaceae): evidence for a pattern of geographical parthenogenesis.

    PubMed

    Róis, Ana Sofia; Sádio, Flávio; Paulo, Octávio S; Teixeira, Generosa; Paes, Ana Paula; Espírito-Santo, Dalila; Sharbel, Timothy F; Caperta, Ana D

    2016-01-01

    The genus Limonium (Plumbaginaceae) has long been recognized to have sexual and apomictic (asexual seed formation) modes of reproduction. This study aimed to elucidate phylogeographical patterns and modes of reproduction in diploid and tetraploid Limonium species, namely three putative sexual diploid species with morphological affinities (L. nydeggeri, L. ovalifolium, L. lanceolatum) and three related, probably apomict tetraploid species (L. binervosum, L. dodartii, L. multiflorum). cpDNA diversity and differentiation between natural populations of the species were investigated using two chloroplast sequence regions (trnL intron and trnL-trnF intergenic spacer). Floral heteromorphies, ovule cytoembryological analyses and pollination and crossing tests were performed in representative species of each ploidy group, namely diploid L. ovalifolium and tetraploid L. multiflorum, using plants from greenhouse collections. Genetic analyses showed that diploid species have a higher haplotype diversity and a higher number of unique (endemic) haplotypes than tetraploid species. Network analysis revealed correlations between cpDNA haplotype distribution and ploidy groups, species groups and geographical origin, and haplotype sharing within and among species with distinct ploidy levels. Reproductive biology analyses showed that diploid L. ovalifolium mainly forms meiotically reduced tetrasporic embryo sacs of Gagea ova, Adoxa and Drusa types. Limonium multiflorum, however, has only unreduced, diplosporic (apomictic) embryo sacs of Rudbeckia type, and autonomous apomictic development seems to occur. Taken together, the findings provide evidence of a pattern of 'geographical parthenogenesis' in which quaternary climatic oscillations appear to be involved in the geographical patterns of coastal diploid and tetraploid Limonium species. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please

  16. Sex at the margins: parthenogenesis vs. facultative and obligate sex in a Neotropical ant.

    PubMed

    Kellner, K; Seal, J N; Heinze, J

    2013-01-01

    Geographic parthenogenesis is a distribution pattern, in which parthenogenetic populations tend to live in marginal habitats, at higher latitudes and altitudes and island-like habitats compared with the sexual forms. The facultatively parthenogenetic ant Platythyrea punctata is thought to exhibit this general pattern throughout its wide range in Central America and the Caribbean Islands. Workers of P. punctata from the Caribbean produce diploid female offspring from unfertilized eggs by thelytokous parthenogenesis, and mated females and males are rare. In contrast, workers in one colony from Costa Rica were incapable of thelytoky; instead mated workers produced all female offspring. Because sample sizes were very low in former studies, we here use microsatellite markers and explicit tests of thelytoky to examine the population genetic structure of ancestral and derived populations of P. punctata throughout the Caribbean and Central America. Populations from the Caribbean islands were fully capable of parthenogenesis, and population genetic signatures indicate that this is the predominant mode of reproduction, although males are occasionally produced. In contrast, the northernmost population on the mainland (Texas) showed signatures of sexual reproduction, and individuals were incapable of reproduction by thelytoky. Contrary to expectations from a geographic parthenogenesis distribution pattern, most parts of the mainland populations were found to be facultatively thelytokous, with population genetic signatures of both sexual and parthenogenetic reproduction. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

  17. Parthenogenesis in birds: a review.

    PubMed

    Ramachandran, R; McDaniel, C D

    2018-06-01

    Parthenogenesis or 'virgin birth' is embryonic development in unfertilized eggs. It is a routine means of reproduction in many invertebrates. However, even though parthenogenesis occurs naturally in even more advanced vertebrates, like birds, it is mostly abortive in nature. In fact, multiple limiting factors, such as delayed and unorganized development as well as unfavorable conditions developing within the unfertilized egg upon incubation, are associated with termination of progressive development of parthenogenetic embryos. In birds, diploid parthenogenesis is automictic and facultative producing only males. However, the mechanisms controlling parthenogenesis in birds are not clearly elucidated. Additionally, it appears from even very recent research that these mechanisms may hinder the normal fertilization process and subsequent embryonic development. For instance, virgin quail and turkey hens exhibiting parthenogenesis have reduced reproductive performance following mating. Also, genetic selection and environmental factors, such as live virus vaccinations, are known to trigger the process of parthenogenesis in birds. Therefore, parthenogenesis has a plausible negative impact on the poultry industry. Hence, a better understanding of parthenogenesis and the mechanisms that control it could benefit commercial poultry production. In this context, the aim of this review is to provide a complete overview of the process of parthenogenesis in birds. © 2018 Society for Reproduction and Fertility.

  18. Parthenogenesis in Komodo dragons.

    PubMed

    Watts, Phillip C; Buley, Kevin R; Sanderson, Stephanie; Boardman, Wayne; Ciofi, Claudio; Gibson, Richard

    2006-12-21

    Parthenogenesis, the production of offspring without fertilization by a male, is rare in vertebrate species, which usually reproduce after fusion of male and female gametes. Here we use genetic fingerprinting to identify parthenogenetic offspring produced by two female Komodo dragons (Varanus komodoensis) that had been kept at separate institutions and isolated from males; one of these females subsequently produced additional offspring sexually. This reproductive plasticity indicates that female Komodo dragons may switch between asexual and sexual reproduction, depending on the availability of a mate--a finding that has implications for the breeding of this threatened species in captivity. Most zoos keep only females, with males being moved between zoos for mating, but perhaps they should be kept together to avoid triggering parthenogenesis and thereby decreasing genetic diversity.

  19. Microtubule organization during human parthenogenesis.

    PubMed

    Terada, Yukihiro; Hasegawa, Hisataka; Ugajin, Tomohisa; Murakami, Takashi; Yaegashi, Nobuo; Okamura, Kunihiro

    2009-04-01

    In human fertilization, the sperm centrosome plays a crucial role as a microtubule organizing center (MTOC). We studied microtubule organization during human parthenogenesis, which occurs when a human egg undergoes cleavage without a sperm centrosome. Multiple cytoplasmic asters were organized in the human oocyte after parthenogenetic activation, indicating that multiple MTOC are present in the human oocyte cytoplasm and function like a human sperm centrosome during parthenogenesis.

  20. Phylogeography and modes of reproduction in diploid and tetraploid halophytes of Limonium species (Plumbaginaceae): evidence for a pattern of geographical parthenogenesis

    PubMed Central

    Róis, Ana Sofia; Sádio, Flávio; Paulo, Octávio S.; Teixeira, Generosa; Paes, Ana Paula; Espírito-Santo, Dalila; Sharbel, Timothy F.; Caperta, Ana D.

    2016-01-01

    Background and Aims The genus Limonium (Plumbaginaceae) has long been recognized to have sexual and apomictic (asexual seed formation) modes of reproduction. This study aimed to elucidate phylogeographical patterns and modes of reproduction in diploid and tetraploid Limonium species, namely three putative sexual diploid species with morphological affinities (L. nydeggeri, L. ovalifolium, L. lanceolatum) and three related, probably apomict tetraploid species (L. binervosum, L. dodartii, L. multiflorum). Methods cpDNA diversity and differentiation between natural populations of the species were investigated using two chloroplast sequence regions (trnL intron and trnL–trnF intergenic spacer). Floral heteromorphies, ovule cytoembryological analyses and pollination and crossing tests were performed in representative species of each ploidy group, namely diploid L. ovalifolium and tetraploid L. multiflorum, using plants from greenhouse collections. Key Results and Conclusions Genetic analyses showed that diploid species have a higher haplotype diversity and a higher number of unique (endemic) haplotypes than tetraploid species. Network analysis revealed correlations between cpDNA haplotype distribution and ploidy groups, species groups and geographical origin, and haplotype sharing within and among species with distinct ploidy levels. Reproductive biology analyses showed that diploid L. ovalifolium mainly forms meiotically reduced tetrasporic embryo sacs of Gagea ova, Adoxa and Drusa types. Limonium multiflorum, however, has only unreduced, diplosporic (apomictic) embryo sacs of Rudbeckia type, and autonomous apomictic development seems to occur. Taken together, the findings provide evidence of a pattern of ‘geographical parthenogenesis’ in which quaternary climatic oscillations appear to be involved in the geographical patterns of coastal diploid and tetraploid Limonium species. PMID:26424783

  1. Photographic Mosaics and Geographic Generalizations: A Perceptual Approach to Geographic Education

    ERIC Educational Resources Information Center

    Castner, Henry W.

    2003-01-01

    If vision can be considered the basis of geographic inquiry, then it must involve looking with discrimination--the ability to discern clues in our surroundings that speak to spatial processes or patterns in all aspects of geography--physical, cultural, economic, and so on. Geographic thinking also involves making spatial generalizations. We do…

  2. Large variation in mitochondrial DNA of sexual and parthenogenetic Dahlica triquetrella (Lepidoptera: Psychidae) shows multiple origins of parthenogenesis

    PubMed Central

    2013-01-01

    Background Obligate parthenogenesis is relatively rare in animals. Still, in some groups it is quite common and has evolved and persisted multiple times. These groups may provide important clues to help solve the ‘paradox of sex’. Several species in the Psychidae (Lepidoptera) have obligate parthenogenesis. Dahlica triquetrella is one of those species where multiple transitions to parthenogenesis are postulated based on intensive cytological and behavioural studies. This has led to the hypothesis that multiple transitions from sexuals to diploid parthenogens occurred during and after the last glacial period, followed by transitions from parthenogenetic diploids to parthenogenetic tetraploids. Our study is the first to test these hypotheses using a molecular phylogeny based on mtDNA from multiple sexual and parthenogenetic populations from a wide geographic range. Results Parthenogenetic (and sexual) D. triquetrella are not monophyletic, and considerable sequence variation is present suggesting multiple transitions to parthenogenesis. However, we could not establish ancestral sexual haplotypes from our dataset. Our data suggest that some parthenogenetic clades have evolved, indicating origins of parthenogenesis before the last glacial period. Conclusions Multiple transitions to parthenogenesis have taken place in Dahlica triquetrella, confirming previous hypotheses. The number of different parthenogenetic clades, haplotypes and their apparent evolutionary age, clearly show that parthenogenesis has been a very successful reproductive strategy in this species over a long period. PMID:23622052

  3. Large variation in mitochondrial DNA of sexual and parthenogenetic Dahlica triquetrella (Lepidoptera: Psychidae) shows multiple origins of parthenogenesis.

    PubMed

    Elzinga, Jelmer A; Jokela, Jukka; Shama, Lisa N S

    2013-04-26

    Obligate parthenogenesis is relatively rare in animals. Still, in some groups it is quite common and has evolved and persisted multiple times. These groups may provide important clues to help solve the 'paradox of sex'. Several species in the Psychidae (Lepidoptera) have obligate parthenogenesis. Dahlica triquetrella is one of those species where multiple transitions to parthenogenesis are postulated based on intensive cytological and behavioural studies. This has led to the hypothesis that multiple transitions from sexuals to diploid parthenogens occurred during and after the last glacial period, followed by transitions from parthenogenetic diploids to parthenogenetic tetraploids. Our study is the first to test these hypotheses using a molecular phylogeny based on mtDNA from multiple sexual and parthenogenetic populations from a wide geographic range. Parthenogenetic (and sexual) D. triquetrella are not monophyletic, and considerable sequence variation is present suggesting multiple transitions to parthenogenesis. However, we could not establish ancestral sexual haplotypes from our dataset. Our data suggest that some parthenogenetic clades have evolved, indicating origins of parthenogenesis before the last glacial period. Multiple transitions to parthenogenesis have taken place in Dahlica triquetrella, confirming previous hypotheses. The number of different parthenogenetic clades, haplotypes and their apparent evolutionary age, clearly show that parthenogenesis has been a very successful reproductive strategy in this species over a long period.

  4. What does the geography of parthenogenesis teach us about sex?

    PubMed

    Tilquin, Anaïs; Kokko, Hanna

    2016-10-19

    Theory predicts that sexual reproduction is difficult to maintain if asexuality is an option, yet sex is very common. To understand why, it is important to pay attention to repeatably occurring conditions that favour transitions to, or persistence of, asexuality. Geographic parthenogenesis is a term that has been applied to describe a large variety of patterns where sexual and related asexual forms differ in their geographic distribution. Often asexuality is stated to occur in a habitat that is, in some sense, marginal, but the interpretation differs across studies: parthenogens might not only predominate near the margin of the sexuals' distribution, but might also extend far beyond the sexual range; they may be disproportionately found in newly colonizable areas (e.g. areas previously glaciated), or in habitats where abiotic selection pressures are relatively stronger than biotic ones (e.g. cold, dry). Here, we review the various patterns proposed in the literature, the hypotheses put forward to explain them, and the assumptions they rely on. Surprisingly, few mathematical models consider geographic parthenogenesis as their focal question, but all models for the evolution of sex could be evaluated in this framework if the (often ecological) causal factors vary predictably with geography. We also recommend broadening the taxa studied beyond the traditional favourites.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'. © 2016 The Author(s).

  5. What does the geography of parthenogenesis teach us about sex?

    PubMed Central

    Kokko, Hanna

    2016-01-01

    Theory predicts that sexual reproduction is difficult to maintain if asexuality is an option, yet sex is very common. To understand why, it is important to pay attention to repeatably occurring conditions that favour transitions to, or persistence of, asexuality. Geographic parthenogenesis is a term that has been applied to describe a large variety of patterns where sexual and related asexual forms differ in their geographic distribution. Often asexuality is stated to occur in a habitat that is, in some sense, marginal, but the interpretation differs across studies: parthenogens might not only predominate near the margin of the sexuals' distribution, but might also extend far beyond the sexual range; they may be disproportionately found in newly colonizable areas (e.g. areas previously glaciated), or in habitats where abiotic selection pressures are relatively stronger than biotic ones (e.g. cold, dry). Here, we review the various patterns proposed in the literature, the hypotheses put forward to explain them, and the assumptions they rely on. Surprisingly, few mathematical models consider geographic parthenogenesis as their focal question, but all models for the evolution of sex could be evaluated in this framework if the (often ecological) causal factors vary predictably with geography. We also recommend broadening the taxa studied beyond the traditional favourites. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’. PMID:27619701

  6. Parthenogenesis induction by Wolbachia in parasitoids

    USDA-ARS?s Scientific Manuscript database

    The maternally inherited intracellular bacterium, Wolbachia pipientis, induces reproductive alterations in host arthropod populations such as male-killing, feminization, parthenogenesis induction (PI, or reproduction without males) and cytoplasmic incompatibility. Here we report that PI in Mexican O...

  7. Thelytokous parthenogenesis in eusocial Hymenoptera.

    PubMed

    Rabeling, Christian; Kronauer, Daniel J C

    2013-01-01

    Female parthenogenesis, or thelytoky, is particularly common in solitary Hymenoptera. Only more recently has it become clear that many eusocial species also regularly reproduce thelytokously, and here we provide a comprehensive overview. Especially in ants, thelytoky underlies a variety of idiosyncratic life histories with unique evolutionary and ecological consequences. In all eusocial species studied, thelytoky probably has a nuclear genetic basis and the underlying cytological mechanism retains high levels of heterozygosity. This is in striking contrast to many solitary wasps, in which thelytoky is often induced by cytoplasmic bacteria and results in an immediate loss of heterozygosity. These differences are likely related to differences in haplodiploid sex determination mechanisms, which in eusocial species usually require heterozygosity for female development. At the same time, haplodiploidy might account for important preadaptations that can help explain the apparent ease with which Hymenoptera transition between sexual and asexual reproduction.

  8. Thelytokous Parthenogenesis in the Ant Myrmecina nipponica (Hymenoptera: Formicidae).

    PubMed

    Masuko, Keiichi

    2014-09-01

    Myrmecina nipponica Wheeler is a terrestrial ant nesting chiefly in the soil in forest. It is a specialized predator of oribatid mites, but also scavenges on a broad spectrum of other arthropods. In the studied population at Cape Manazuru in central Japan, M. nipponica colonies are typically monogynous, and previous dissections of queens suggested that these individuals were not inseminated, thus suggesting these ants can reproduce via thelytokous parthenogenesis. To test for thelytokous parthenogenesis in M. nipponica the spermathecae of queens (dealate gynes) from worker-containing colonies were histologically examined in detail. All specimens examined (n=5) had no spermatozoa in the spermatheca. In addition, a total of four colony-founding queens were reared in isolation in the laboratory to test whether non-inseminated females were capable of egg laying and to test whether female offspring emerged from this brood. In all of four culture replicates, only new workers were produced from the eggs those queens had laid and male offspring was absent. After the breeding experiment, the queens' spermathecae were histologically examined and no sperm were detected in their spermathecae. These results reveal that M. nipponica queens of the Manazuru population are capable of producing female offspring thelytokously. Sexual reproduction by typical gynes and also by intermorphs has been known from other local populations of M. nipponica; therefore, this species shows geographical polymorphism in sexuality.

  9. Undergraduate teaching in UK general practice: a geographical snapshot.

    PubMed

    Derbyshire, Helen; Rees, Eliot; Gay, Simon P; McKinley, Robert K

    2014-06-01

    Learning in general practice is an essential component of undergraduate medical education; currently, on average, 13% of clinical placements in the UK are in general practice. However, whether general practice can sustainably deliver more undergraduate placements is uncertain. To identify the geographical distribution of undergraduate teaching practices and their distance from the host medical school. National survey of all medical schools in the UK. All 33 UK medical schools were invited to provide the postcodes of their undergraduate teaching practices. These were collated, de-duplicated, and mapped. The distance in kilometres and journey times by car and public transport between each medical school and its teaching practices was estimated using Transport Direct (www.transportdirect.info). The postcodes of every practice in the UK were obtained from the UK's health departments. All 33 UK medical schools responded; 4392 practices contributed to teaching, with a median (minimum-maximum) of 142 (17-385) practices per school. The median (minimum-maximum) distance between a school and a teaching practice was 28 km (0-1421 km), 41 (0:00-23:26) minutes' travel by car and 1 hour 12 (0:00-17:29) minutes' travel by public transport. All teaching practices were accessible by public transport in one school and 90-99% were in a further four schools; 24 schools had >20% of practices that were inaccessible by public transport. The 4392 undergraduate teaching general practices are widely distributed and potentially any practice, no matter how isolated, could contribute to undergraduate education. However, this is, at the price of a considerable travel burden. © British Journal of General Practice 2014.

  10. Undergraduate teaching in UK general practice: a geographical snapshot

    PubMed Central

    Derbyshire, Helen; Rees, Eliot; Gay, Simon P; McKinley, Robert K

    2014-01-01

    Background Learning in general practice is an essential component of undergraduate medical education; currently, on average, 13% of clinical placements in the UK are in general practice. However, whether general practice can sustainably deliver more undergraduate placements is uncertain. Aim To identify the geographical distribution of undergraduate teaching practices and their distance from the host medical school. Design and setting National survey of all medical schools in the UK. Method All 33 UK medical schools were invited to provide the postcodes of their undergraduate teaching practices. These were collated, de-duplicated, and mapped. The distance in kilometres and journey times by car and public transport between each medical school and its teaching practices was estimated using Transport Direct (www.transportdirect.info). The postcodes of every practice in the UK were obtained from the UK’s health departments. Results All 33 UK medical schools responded; 4392 practices contributed to teaching, with a median (minimum–maximum) of 142 (17–385) practices per school. The median (minimum–maximum) distance between a school and a teaching practice was 28 km (0–1421 km), 41 (0:00–23:26) minutes’ travel by car and 1 hour 12 (0:00–17:29) minutes’ travel by public transport. All teaching practices were accessible by public transport in one school and 90–99% were in a further four schools; 24 schools had >20% of practices that were inaccessible by public transport. Conclusion The 4392 undergraduate teaching general practices are widely distributed and potentially any practice, no matter how isolated, could contribute to undergraduate education. However, this is, at the price of a considerable travel burden. PMID:24868071

  11. Genetic selection increases parthenogenesis in Chinese painted quail (Coturnix chinensis).

    PubMed

    Parker, H M; Kiess, A S; Wells, J B; Young, K M; Rowe, D; McDaniel, C D

    2010-07-01

    Parthenogenesis, embryonic development of an unfertilized egg, occurs naturally in turkey, chicken, and quail species. In fact, parthenogenesis in turkeys and chickens can be increased by genetic selection. However, it is unknown if genetic selection for parthenogenesis is effective in quail or if selection for parthenogenesis affects egg production. Therefore, the objectives of this study were to determine if the incidence of parthenogenesis in quail could be increased by genetic selection and if selection for this trait affects egg production. To prevent fertilization, 1,090 females were caged separately from males at 4 wk of age and then caged individually at 6 wk of age to monitor egg production. Eggs were collected daily, labeled, and stored for 0 to 3 d. After 10 d of incubation, 20 unfertilized eggs from each hen were examined for the occurrence of parthenogenesis and embryonic growth. In the parent (P) generation and subsequent generations (1 to 4), hens laying eggs containing parthenogenetic development and males whose sisters or mothers exhibited parthenogenesis were used for breeding. There was a linear increase in the percentage of hens exhibiting parthenogenesis as generation of selection increased. With each successive generation, there was a quadratic response in the percentage of eggs positive for parthenogenesis. When compared with the P generation, parthenogenesis was almost 3 times greater for eggs laid by the fourth generation (4.6 to 12.5%, respectively). Even when only hens exhibiting parthenogenesis were examined, the percentage of eggs demonstrating embryonic development responded quadratically with generation of selection. The embryonic size at 10 d of incubation was greater for each subsequent generation when compared with the P generation. There was a linear decrease in both egg production and the average position of an egg in a clutch as generation of selection increased. In conclusion, genetic selection for parthenogenesis increased the

  12. Occurrence of Parthenogenesis in Potato Tuber Moth

    PubMed Central

    Liu, Yan; Hu, Chun-Hua; Wang, Chun-Ya; Xiong, Yan; Li, Zong-Kai; Xiao, Chun

    2018-01-01

    Abstract Parthenogenesis, a natural form of asexual reproduction produced from unfertilized eggs, occurs in many insects in Hemiptera and Hymenoptera, but very rarely in Lepidoptera. The current study aimed to test the larval density dependent occurrence of parthenogenesis in potato tuber moth, Phthorimaea operculella (Zeller; Lepidoptera: Gelechiidae) under laboratory conditions. More than 10% of females out of 25 tested females that developed from the high larval density treatment at 45 larvae per tuber were capable to reproduce asexually. Both male and female offspring were produced parthenogenetically. The sexually reproductive offspring of a laboratory parthenogenetic population had a lower egg hatch rate, shorter larval stage, and shorter male life span when compared with the non-parthenogenetic population. This suggests that the sexually reproductive offspring of parthenogenetic population have a decreased overall fitness compared to the sexually reproductive offspring of non-parthenogenetic population.

  13. Facultative parthenogenesis in vertebrates: reproductive error or chance?

    PubMed

    Lampert, K P

    2008-01-01

    Parthenogenesis, the development of an embryo from a female gamete without any contribution of a male gamete, is very rare in vertebrates. Parthenogenetically reproducing species have, so far, only been found in the Squamate reptiles (lizards and snakes). Facultative parthenogenesis, switching between sexual and clonal reproduction, although quite common in invertebrates, e.g. Daphnia and aphids, seems to be even rarer in vertebrates. However, isolated cases of parthenogenetic development have been reported in all vertebrate groups. Facultative parthenogenesis in vertebrates has only been found in captive animals but might simply have been overlooked in natural populations. Even though its evolutionary impact is hard to determine and very likely varies depending on the ploidy restoration mechanisms and sex-determining mechanisms involved, facultative parthenogenesis is already discussed in conservation biology and medical research. To raise interest for facultative parthenogenesis especially in evolutionary biology, I summarize the current knowledge about facultative parthenogenesis in the different vertebrate groups, introduce mechanisms of diploid oocyte formation and discuss the genetic consequences and potential evolutionary impact of facultative parthenogenesis in vertebrates.

  14. Thelytokous parthenogenesis and its consequences on inbreeding in an ant.

    PubMed

    Pearcy, M; Hardy, O; Aron, S

    2006-05-01

    Thelytokous parthenogenesis, that is, the production of diploid daughters from unfertilized eggs, may involve various cytological mechanisms, each having a different impact on the genetic structure of populations. Here, we determined the cytological mechanism of thelytokous parthenogenesis and its impact on inbreeding in the ant Cataglyphis cursor, a species where queens use both sexual and asexual reproduction to produce, respectively, workers and new queens. It has been suggested that thelytokous parthenogenesis in C. cursor might have been selected for to face high queen mortality and, originally, to allow workers to replace the queen when she passes away. We first determined the mode of thelytokous parthenogenesis by comparing the rate of transition to homozygosity at four highly polymorphic loci to expectations under the different modes of parthenogenesis. Our data show that thelytoky is achieved through automictic parthenogenesis with central fusion. We then estimated the proportion of colonies headed by worker-produced queens in a natural population. We designed a model linking the observed homozygosity in queens to the proportion of queens produced by workers, based on the assumption that (i) parthenogenesis is automictic with central fusion and (ii) queen lineage is asexually produced, resulting in an increase of the inbreeding over generations, whereas workers are sexually produced and therefore not inbred. Our results indicate that more than 60% of the colonies should be headed by a worker-produced queen, suggesting that queen's lifespan is low in this species.

  15. Patterns and mechanisms in instances of endosymbiont-induced parthenogenesis.

    PubMed

    Ma, W-J; Schwander, T

    2017-05-01

    Female-producing parthenogenesis can be induced by endosymbionts that increase their transmission by manipulating host reproduction. Our literature survey indicates that such endosymbiont-induced parthenogenesis is known or suspected in 124 host species from seven different arthropod taxa, with Wolbachia as the most frequent endosymbiont (in 56-75% of host species). Most host species (81%, 100 out of 124) are characterized by haplo-diploid sex determination, but a strong ascertainment bias likely underestimates the frequency of endosymbiont-induced parthenogenesis in hosts with other sex determination systems. In at least one taxon, hymenopterans, endosymbionts are a significant driver of transitions from sexual to parthenogenetic reproduction, with one-third of lineages being parthenogenetic as a consequence of endosymbiont infection. Endosymbiont-induced parthenogenesis appears to facilitate the maintenance of reproductive polymorphism: at least 50% of species comprise both sexual (uninfected) and parthenogenetic (infected) strains. These strains feature distribution differences similar to the ones documented for lineages with genetically determined parthenogenesis, with endosymbiont-induced parthenogens occurring at higher latitudes than their sexual relatives. Finally, although gamete duplication is often considered as the main mechanism for endosymbiont-induced parthenogenesis, it underlies parthenogenesis in only half of the host species studied thus far. We point out caveats in the methods used to test for endosymbiont-induced parthenogenesis and suggest specific approaches that allow for firm conclusions about the involvement of endosymbionts in the origin of parthenogenesis. © 2017 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.

  16. Facultative parthenogenesis discovered in wild vertebrates.

    PubMed

    Booth, Warren; Smith, Charles F; Eskridge, Pamela H; Hoss, Shannon K; Mendelson, Joseph R; Schuett, Gordon W

    2012-12-23

    Facultative parthenogenesis (FP)-asexual reproduction by bisexual species-has been documented in a variety of multi-cellular organisms but only recently in snakes, varanid lizards, birds and sharks. Unlike the approximately 80 taxa of unisexual reptiles, amphibians and fishes that exist in nature, FP has yet to be documented in the wild. Based on captive documentation, it appears that FP is widespread in squamate reptiles (snakes, lizards and amphisbaenians), and its occurrence in nature seems inevitable, yet the task of detecting FP in wild individuals has been deemed formidable. Here we show, using microsatellite DNA genotyping and litter characteristics, the first cases of FP in wild-collected pregnant females and their offspring of two closely related species of North American pitviper snakes-the copperhead (Agkistrodon contortrix) and cottonmouth (Agkistrodon piscivorus). Our findings support the view that non-hybrid origins of parthenogenesis, such as FP, are more common in squamates than previously thought. With this confirmation, FP can no longer be viewed as a rare curiosity outside the mainstream of vertebrate evolution. Future research on FP in squamate reptiles related to proximate control of induction, reproductive competence of parthenogens and population genetics modelling is warranted.

  17. Facultative parthenogenesis discovered in wild vertebrates

    PubMed Central

    Booth, Warren; Smith, Charles F.; Eskridge, Pamela H.; Hoss, Shannon K.; Mendelson, Joseph R.; Schuett, Gordon W.

    2012-01-01

    Facultative parthenogenesis (FP)—asexual reproduction by bisexual species—has been documented in a variety of multi-cellular organisms but only recently in snakes, varanid lizards, birds and sharks. Unlike the approximately 80 taxa of unisexual reptiles, amphibians and fishes that exist in nature, FP has yet to be documented in the wild. Based on captive documentation, it appears that FP is widespread in squamate reptiles (snakes, lizards and amphisbaenians), and its occurrence in nature seems inevitable, yet the task of detecting FP in wild individuals has been deemed formidable. Here we show, using microsatellite DNA genotyping and litter characteristics, the first cases of FP in wild-collected pregnant females and their offspring of two closely related species of North American pitviper snakes—the copperhead (Agkistrodon contortrix) and cottonmouth (Agkistrodon piscivorus). Our findings support the view that non-hybrid origins of parthenogenesis, such as FP, are more common in squamates than previously thought. With this confirmation, FP can no longer be viewed as a rare curiosity outside the mainstream of vertebrate evolution. Future research on FP in squamate reptiles related to proximate control of induction, reproductive competence of parthenogens and population genetics modelling is warranted. PMID:22977071

  18. Contagious parthenogenesis, automixis, and a sex determination meltdown.

    PubMed

    Engelstädter, Jan; Sandrock, Christoph; Vorburger, Christoph

    2011-02-01

    Because of the twofold cost of sex, genes conferring asexual reproduction are expected to spread rapidly in sexual populations. However, in reality this simple prediction is often confounded by several complications observed in natural systems. Motivated by recent findings in the Cape honey bee and in the parasitoid wasp Lysiphlebus fabarum, we explore through mathematical models the spread of a recessive, parthenogenesis inducing allele in a haplodiploid population. The focus of these models is on the intricate interactions between the mode of parthenogenesis induction through automixis and complementary sex determination (CSD) systems. These interactions may result in asexual production of diploid male offspring and the spread of the parthenogenesis-inducing allele through these males. We demonstrate that if parthenogenetic females produce a substantial proportion of male offspring, this may prevent the parthenogenesis-inducing allele from spreading. However, this effect is weakened if these diploid males are at least partially fertile. We also predict a degradation of multilocus CSD systems during the spread of parthenogenesis, following which only a single polymorphic CSD locus is maintained. Finally, based on empirical parameter estimates from L. fabarum we predict that male production in parthenogens is unlikely to prevent the eventual loss of sexual reproduction in this system. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.

  19. Exploratory spatial analysis of pilot fatality rates in general aviation crashes using geographic information systems.

    PubMed

    Grabowski, Jurek G; Curriero, Frank C; Baker, Susan P; Li, Guohua

    2002-03-01

    Geographic information systems and exploratory spatial analysis were used to describe the geographic characteristics of pilot fatality rates in 1983-1998 general aviation crashes within the continental United States. The authors plotted crash sites on a digital map; rates were computed at regular grid intersections and then interpolated by using geographic information systems. A test for significance was performed by using Monte Carlo simulations. Further analysis compared low-, medium-, and high-rate areas in relation to pilot characteristics, aircraft type, and crash circumstance. Of the 14,051 general aviation crashes studied, 31% were fatal. Seventy-four geographic areas were categorized as having low fatality rates and 53 as having high fatality rates. High-fatality-rate areas tended to be mountainous, such as the Rocky Mountains and the Appalachian region, whereas low-rate areas were relatively flat, such as the Great Plains. Further analysis comparing low-, medium-, and high-fatality-rate areas revealed that crashes in high-fatality-rate areas were more likely than crashes in other areas to have occurred under instrument meteorologic conditions and to involve aircraft fire. This study demonstrates that geographic information systems are a valuable tool for injury prevention and aviation safety research.

  20. Genetic variation and origin of parthenogenesis in the Aspidoscelis cozumela complex: evidence from mitochondrial genes.

    PubMed

    Manríquez-Morán, Norma L; Cruz, Fausto R Méndez-de la; Murphy, Robert W

    2014-01-01

    Parthenogenesis is a form of clonal reproduction. Eggs develop in the absence of sperm and offspring are genetically identical to their mother. Although common in invertebrates, it occurs in only a few species of squamate reptiles. Parthenogenetic reptiles have their origin in interspecific hybridization, and their populations are exclusively female. Because of its high mutation rate and maternal inheritance, mitochondrial DNA sequence data can evaluate the origin and evolution of all-female vertebrates. Partial sequences from two mitochondrial genes, Cytb and ND4, were analyzed to investigate questions about the origin of parthenogenesis in the Aspidoscelis cozumela complex, which includes A. cozumela, A. maslini and A. rodecki. Low levels of divergence were detected among parthenogenetic species, and between them and A. angusticeps, confirming it as the maternal species of the parthenoforms. A gene tree was constructed using sequences from three populations of A. angusticeps and nine of its unisexual daughter species. The phylogeny suggests that two independent hybridization events between A. angusticeps and A. deppii formed three unisexual species. One hybridization resulted in A. rodecki and the other formed A. maslini and A. cozumela. Although A. cozumela has the haplotype characteristic of A. maslini from Puerto Morelos, it is considered to be a different species based on karyological and morphological characteristics and its geographical isolation.

  1. Facultative parthenogenesis in the Ryukyu drywood termite Neotermes koshunensis

    PubMed Central

    Kobayashi, Kazuya; Miyaguni, Yasushi

    2016-01-01

    Parthenogenesis is a relatively rare reproductive mode in nature compared to sex. In social insects, the evolution of parthenogenesis has a notable impact on their life histories. Some termites with parthenogenetic ability produce numerous non-dispersing supplementary queens asexually, whereas other castes are produced via sexual reproduction. This asexual queen succession (AQS) system is adaptive because hundreds of the asexual queens improve the reproductive potential of the colony and maintain the genetic diversity within the colony. However, the evolutionary process of the AQS system remains unclear because parthenogenetic species without this system are unknown. Here, we report facultative parthenogenesis in the drywood termite Neotermes koshunensis. Although the eggs produced by females isolated from males hatched, the hatching rate of those eggs was lower than that of the eggs produced by females kept with males. These parthenogenetic offspring inherited only the maternal alleles and showed high homozygosity, which indicates that the mechanism of ploidy restoration is terminal fusion. A previous study showed that most colonies of this species have a single queen or orphan; thus, the AQS system has not evolved despite their parthenogenetic ability. Further investigations of N. koshunensis will reveal how parthenogenesis evolved and its role in the insect societies. PMID:27464523

  2. Transcriptome Analysis of Thermal Parthenogenesis of the Domesticated Silkworm.

    PubMed

    Liu, Peigang; Wang, Yongqiang; Du, Xin; Yao, Lusong; Li, Fengbo; Meng, Zhiqi

    2015-01-01

    Thermal induction of parthenogenesis (also known as thermal parthenogenesis) in silkworms is an important technique that has been used in artificial insemination, expansion of hybridization, transgenesis and sericultural production; however, the exact mechanisms of this induction remain unclear. This study aimed to investigate the gene expression profile in silkworms undergoing thermal parthenogenesis using RNA-seq analysis. The transcriptome profiles indicated that in non-induced and induced eggs, the numbers of differentially expressed genes (DEGs) for the parthenogenetic line (PL) and amphigenetic line (AL) were 538 and 545, respectively, as determined by fold-change ≥ 2. Gene ontology (GO) analysis showed that DEGs between two lines were mainly involved in reproduction, formation of chorion, female gamete generation and cell development pathways. Upregulation of many chorion genes in AL suggests that the maturation rate of AL eggs was slower than PL eggs. Some DEGs related to reactive oxygen species removal, DNA repair and heat shock response were differentially expressed between the two lines, such as MPV-17, REV1 and HSP68. These results supported the view that a large fraction of genes are differentially expressed between PL and AL, which offers a new approach to identifying the molecular mechanism of silkworm thermal parthenogenesis.

  3. Parthenogenesis: birth of a new lineage or reproductive accident?

    PubMed

    van der Kooi, Casper J; Schwander, Tanja

    2015-08-03

    Parthenogenesis - the ability to produce offspring from unfertilized eggs - is widespread among invertebrates and now increasingly found in normally sexual vertebrates. Are these cases reproductive errors or could they be a first step in the emergence of new parthenogenetic lineages? Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. A high incidence of parthenogenesis in agricultural pests.

    PubMed

    Hoffmann, Ary A; Reynolds, K Tracy; Nash, Michael A; Weeks, Andrew R

    2008-11-07

    Parthenogenetic species are assumed to represent evolutionary dead ends, yet parthenogenesis is common in some groups of invertebrates particularly in those found in relatively constant environments. This suggests that parthenogenetic reproduction might be common in pest invertebrates from uniform agricultural environments. Based on the evaluations of two databases from North America and Italy, we found that parthenogenetic species comprised 45 per cent (North America) or 48 per cent (Italy) of pest species derived from genera where parthenogenesis occurred, compared with an overall incidence of 10 per cent or 16 per cent in these genera. In establishing these patterns, we included only genera containing at least some member species that reproduced by parthenogenesis. The high incidence of parthenogenesis in pest species is spread across different families and several insect orders. Parthenogenetic reproduction may be favoured in agricultural environments when particular clones have a high fitness across multiple generations. Increasing the complexity and variability of agricultural environments represents one way of potentially controlling parthenogenetic pest species.

  5. Facultative parthenogenesis in the Ryukyu drywood termite Neotermes koshunensis.

    PubMed

    Kobayashi, Kazuya; Miyaguni, Yasushi

    2016-07-28

    Parthenogenesis is a relatively rare reproductive mode in nature compared to sex. In social insects, the evolution of parthenogenesis has a notable impact on their life histories. Some termites with parthenogenetic ability produce numerous non-dispersing supplementary queens asexually, whereas other castes are produced via sexual reproduction. This asexual queen succession (AQS) system is adaptive because hundreds of the asexual queens improve the reproductive potential of the colony and maintain the genetic diversity within the colony. However, the evolutionary process of the AQS system remains unclear because parthenogenetic species without this system are unknown. Here, we report facultative parthenogenesis in the drywood termite Neotermes koshunensis. Although the eggs produced by females isolated from males hatched, the hatching rate of those eggs was lower than that of the eggs produced by females kept with males. These parthenogenetic offspring inherited only the maternal alleles and showed high homozygosity, which indicates that the mechanism of ploidy restoration is terminal fusion. A previous study showed that most colonies of this species have a single queen or orphan; thus, the AQS system has not evolved despite their parthenogenetic ability. Further investigations of N. koshunensis will reveal how parthenogenesis evolved and its role in the insect societies.

  6. A high incidence of parthenogenesis in agricultural pests

    PubMed Central

    Hoffmann, Ary A; Tracy Reynolds, K; Nash, Michael A; Weeks, Andrew R

    2008-01-01

    Parthenogenetic species are assumed to represent evolutionary dead ends, yet parthenogenesis is common in some groups of invertebrates particularly in those found in relatively constant environments. This suggests that parthenogenetic reproduction might be common in pest invertebrates from uniform agricultural environments. Based on the evaluations of two databases from North America and Italy, we found that parthenogenetic species comprised 45 per cent (North America) or 48 per cent (Italy) of pest species derived from genera where parthenogenesis occurred, compared with an overall incidence of 10 per cent or 16 per cent in these genera. In establishing these patterns, we included only genera containing at least some member species that reproduced by parthenogenesis. The high incidence of parthenogenesis in pest species is spread across different families and several insect orders. Parthenogenetic reproduction may be favoured in agricultural environments when particular clones have a high fitness across multiple generations. Increasing the complexity and variability of agricultural environments represents one way of potentially controlling parthenogenetic pest species. PMID:18647717

  7. Transcriptome Analysis of Thermal Parthenogenesis of the Domesticated Silkworm

    PubMed Central

    Du, Xin; Yao, Lusong; Li, Fengbo; Meng, Zhiqi

    2015-01-01

    Thermal induction of parthenogenesis (also known as thermal parthenogenesis) in silkworms is an important technique that has been used in artificial insemination, expansion of hybridization, transgenesis and sericultural production; however, the exact mechanisms of this induction remain unclear. This study aimed to investigate the gene expression profile in silkworms undergoing thermal parthenogenesis using RNA-seq analysis. The transcriptome profiles indicated that in non-induced and induced eggs, the numbers of differentially expressed genes (DEGs) for the parthenogenetic line (PL) and amphigenetic line (AL) were 538 and 545, respectively, as determined by fold-change ≥ 2. Gene ontology (GO) analysis showed that DEGs between two lines were mainly involved in reproduction, formation of chorion, female gamete generation and cell development pathways. Upregulation of many chorion genes in AL suggests that the maturation rate of AL eggs was slower than PL eggs. Some DEGs related to reactive oxygen species removal, DNA repair and heat shock response were differentially expressed between the two lines, such as MPV-17, REV1 and HSP68. These results supported the view that a large fraction of genes are differentially expressed between PL and AL, which offers a new approach to identifying the molecular mechanism of silkworm thermal parthenogenesis. PMID:26274803

  8. Facultative parthenogenesis in a critically endangered wild vertebrate.

    PubMed

    Fields, Andrew T; Feldheim, Kevin A; Poulakis, Gregg R; Chapman, Demian D

    2015-06-01

    Facultative parthenogenesis - the ability of sexually reproducing species to sometimes produce offspring asexually - is known from a wide range of ordinarily sexually reproducing vertebrates in captivity, including some birds, reptiles and sharks [1-3]. Despite this, free-living parthenogens have never been observed in any of these taxa in the wild, although two free-living snakes were recently discovered each gestating a single parthenogen - one copperhead (Agkistrodon contortrix) and one cottonmouth (Agkistrodon piscivorus) [1]. Vertebrate parthenogens are characterized as being of the homogametic sex (e.g., females in sharks, males in birds) and by having elevated homozygosity compared to their mother [1-3], which may reduce their viability [4]. Although it is unknown if either of the parthenogenetic snakes would have been carried to term or survived in the wild, facultative parthenogenesis might have adaptive significance [1]. If this is true, it is reasonable to hypothesize that parthenogenesis would be found most often at low population density, when females risk reproductive failure because finding mates is difficult [5]. Here, we document the first examples of viable parthenogens living in a normally sexually reproducing wild vertebrate, the smalltooth sawfish (Pristis pectinata). We also provide a simple approach to screen any microsatellite DNA database for parthenogens, which will enable hypothesis-driven research on the significance of vertebrate parthenogenesis in the wild. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Geographical Pattern and Environmental Correlates of Regional-Scale General Flowering in Peninsular Malaysia

    PubMed Central

    Numata, Shinya; Yasuda, Masatoshi; Suzuki, Ryo O.; Hosaka, Tetsuro; Noor, Nur Supardi Md.; Fletcher, Christine D.; Hashim, Mazlan

    2013-01-01

    In South-East Asian dipterocarp forests, many trees synchronize their reproduction at the community level, but irregularly, in a phenomenon known as general flowering (GF). Several proximate cues have been proposed as triggers for the synchronization of Southeast Asian GF, but the debate continues, as many studies have not considered geographical variation in climate and flora. We hypothesized that the spatial pattern of GF forests is explained by previously proposed climatic cues if there are common cues for GF among regions. During the study, GF episodes occurred every year, but the spatial occurrence varied considerably from just a few forests to the whole of Peninsular Malaysia. In 2001, 2002 and 2005, minor and major GF occurred widely throughout Peninsular Malaysia (GF2001, GF2002, and GF2005), and the geographical patterns of GF varied between the episodes. In the three regional-scale GF episodes, most major events occurred in regions where prolonged drought (PD) had been recorded prior, and significant associations between GF scores and PD were found in GF2001 and GF2002. However, the frequency of PD was higher than that of GF throughout the peninsula. In contrast, low temperature (LT) was observed during the study period only before GF2002 and GF2005, but there was no clear spatial relationship between GF and LT in the regional-scale episodes. There was also no evidence that last GF condition influenced the magnitude of GF. Thus, our results suggest that PD would be essential to trigger regional-scale GF in the peninsula, but also that PD does not fully explain the spatial and temporal patterns of GF. The coarse relationships between GF and the proposed climatic cues may be due to the geographical variation in proximate cues for GF, and the climatic and floristic geographical variations should be considered to understand the proximate factors of GF. PMID:24260159

  10. Geographical pattern and environmental correlates of regional-scale general flowering in Peninsular Malaysia.

    PubMed

    Numata, Shinya; Yasuda, Masatoshi; Suzuki, Ryo O; Hosaka, Tetsuro; Noor, Nur Supardi Md; Fletcher, Christine D; Hashim, Mazlan

    2013-01-01

    In South-East Asian dipterocarp forests, many trees synchronize their reproduction at the community level, but irregularly, in a phenomenon known as general flowering (GF). Several proximate cues have been proposed as triggers for the synchronization of Southeast Asian GF, but the debate continues, as many studies have not considered geographical variation in climate and flora. We hypothesized that the spatial pattern of GF forests is explained by previously proposed climatic cues if there are common cues for GF among regions. During the study, GF episodes occurred every year, but the spatial occurrence varied considerably from just a few forests to the whole of Peninsular Malaysia. In 2001, 2002 and 2005, minor and major GF occurred widely throughout Peninsular Malaysia (GF2001, GF2002, and GF2005), and the geographical patterns of GF varied between the episodes. In the three regional-scale GF episodes, most major events occurred in regions where prolonged drought (PD) had been recorded prior, and significant associations between GF scores and PD were found in GF2001 and GF2002. However, the frequency of PD was higher than that of GF throughout the peninsula. In contrast, low temperature (LT) was observed during the study period only before GF2002 and GF2005, but there was no clear spatial relationship between GF and LT in the regional-scale episodes. There was also no evidence that last GF condition influenced the magnitude of GF. Thus, our results suggest that PD would be essential to trigger regional-scale GF in the peninsula, but also that PD does not fully explain the spatial and temporal patterns of GF. The coarse relationships between GF and the proposed climatic cues may be due to the geographical variation in proximate cues for GF, and the climatic and floristic geographical variations should be considered to understand the proximate factors of GF.

  11. The Crash Intensity Evaluation Using General Centrality Criterions and a Geographically Weighted Regression

    NASA Astrophysics Data System (ADS)

    Ghadiriyan Arani, M.; Pahlavani, P.; Effati, M.; Noori Alamooti, F.

    2017-09-01

    Today, one of the social problems influencing on the lives of many people is the road traffic crashes especially the highway ones. In this regard, this paper focuses on highway of capital and the most populous city in the U.S. state of Georgia and the ninth largest metropolitan area in the United States namely Atlanta. Geographically weighted regression and general centrality criteria are the aspects of traffic used for this article. In the first step, in order to estimate of crash intensity, it is needed to extract the dual graph from the status of streets and highways to use general centrality criteria. With the help of the graph produced, the criteria are: Degree, Pageranks, Random walk, Eccentricity, Closeness, Betweenness, Clustering coefficient, Eigenvector, and Straightness. The intensity of crash point is counted for every highway by dividing the number of crashes in that highway to the total number of crashes. Intensity of crash point is calculated for each highway. Then, criteria and crash point were normalized and the correlation between them was calculated to determine the criteria that are not dependent on each other. The proposed hybrid approach is a good way to regression issues because these effective measures result to a more desirable output. R2 values for geographically weighted regression using the Gaussian kernel was 0.539 and also 0.684 was obtained using a triple-core cube. The results showed that the triple-core cube kernel is better for modeling the crash intensity.

  12. Parthenogenesis maintains male sterility in a gynodioecious orchid.

    PubMed

    Huang, Shuang-Quan; Lu, Yang; Chen, Ying-Zhuo; Luo, Yi-Bo; Delph, Lynda F

    2009-10-01

    The invasion of male-sterile (female) individuals into hermaphroditic populations, leading to gynodioecy, is common in flowering plants. Both theoretical and empirical studies have shown that as the frequency of females increases in a population, pollen limitation reduces seed production more in females than in hermaphrodites, leading to higher fitness for hermaphrodites and a consequent decrease in female frequency. Here we show that contrary to this expectation, females of the gynodioecious orchid Satyrium ciliatum are maintained only in populations that experience high pollen limitation caused by low pollinator service and high pollen herbivory. This species avoids the typical problem of pollen limitation for seed production and can therefore maintain high frequencies of females in pollen-limited populations because females produce more seeds than hermaphrodites via facultative parthenogenesis in the absence of pollinia. Our results therefore demonstrate that parthenogenesis is a novel mechanism favoring the maintenance of gynodioecy.

  13. Androgenesis, gynogenesis, and parthenogenesis haploids in cucurbit species.

    PubMed

    Dong, Yan-Qi; Zhao, Wei-Xing; Li, Xiao-Hui; Liu, Xi-Cun; Gao, Ning-Ning; Huang, Jin-Hua; Wang, Wen-Ying; Xu, Xiao-Li; Tang, Zhen-Hai

    2016-10-01

    Haploids and doubled haploids are critical components of plant breeding. This review is focused on studies on haploids and double haploids inducted in cucurbits through in vitro pollination with irradiated pollen, unfertilized ovule/ovary culture, and anther/microspore culture during the last 30 years, as well as comprehensive analysis of the main factors of each process and comparison between chromosome doubling and ploidy identification methods, with special focus on the application of double haploids in plant breeding and genetics. This review identifies existing problems affecting the efficiency of androgenesis, gynogenesis, and parthenogenesis in cucurbit species. Donor plant genotypes and surrounding environments, developmental stages of explants, culture media, stress factors, and chromosome doubling and ploidy identification are compared at length and discussed as methodologies and protocols for androgenesis, gynogenesis, and parthenogenesis in haploid and double haploid production technologies.

  14. Isogenic transgenic homozygous fish induced by artificial parthenogenesis.

    PubMed

    Nam, Y K; Cho, Y S; Kim, D S

    2000-12-01

    As a model system for vertebrate transgenesis, fish have many attractive advantages, especially with respect to the characteristics of eggs, allowing us to produce isogenic, transgenic, homozygous vertebrates by combining with chromosome-set manipulation. Here, we describe the large-scale production of isogenic transgenic homozygous animals using our experimental organism, the mud loach Misgurnus mizolepis, by the simple process of artificial parthenogenesis in a single generation. These isogenic fish have retained transgenic homozygous status in a stable manner during the subsequent 5 years, and exhibited increased levels of transgene expression. Furthermore, their isogenic nature was confirmed by cloned transgenic homozygous offspring produced via another step of parthenogenic reproduction of the isogenic homozygous transgenic fish. These results demonstrate that a combination of transgenesis and artificial parthenogenesis will make the rapid utilization of genetically pure homozygous transgenic system in vertebrate transgenesis possible.

  15. A Study of the Geographic Origin, Education, and Experience of Hotel General Managers. RHI 590 Individual Project

    DTIC Science & Technology

    1993-04-01

    Chicago Hilton and Towers. Among the four-star properties are those of Ritz - Carlton , Nikko, Four Seasons, and other famous properties such as the famed...COVERED April 1993 THESIS/D O_ _ 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS A Study of the Geographic Origin, Education, and Experience of Hotel General...GEOGRAPHIC ORIGIN, EDUCATION, AND EXPERIENCE OF HOTEL GENERAL MANAGERS RHI 590 INDIVIDUAL PROJECT BY: Alan Christopher Gnann April 30, 1993 PURDUE UNIVERSITY

  16. Comparative Genomics of a Parthenogenesis-Inducing Wolbachia Symbiont

    PubMed Central

    Lindsey, Amelia R. I.; Werren, John H.; Richards, Stephen; Stouthamer, Richard

    2016-01-01

    Wolbachia is an intracellular symbiont of invertebrates responsible for inducing a wide variety of phenotypes in its host. These host-Wolbachia relationships span the continuum from reproductive parasitism to obligate mutualism, and provide a unique system to study genomic changes associated with the evolution of symbiosis. We present the genome sequence from a parthenogenesis-inducing Wolbachia strain (wTpre) infecting the minute parasitoid wasp Trichogramma pretiosum. The wTpre genome is the most complete parthenogenesis-inducing Wolbachia genome available to date. We used comparative genomics across 16 Wolbachia strains, representing five supergroups, to identify a core Wolbachia genome of 496 sets of orthologous genes. Only 14 of these sets are unique to Wolbachia when compared to other bacteria from the Rickettsiales. We show that the B supergroup of Wolbachia, of which wTpre is a member, contains a significantly higher number of ankyrin repeat-containing genes than other supergroups. In the wTpre genome, there is evidence for truncation of the protein coding sequences in 20% of ORFs, mostly as a result of frameshift mutations. The wTpre strain represents a conversion from cytoplasmic incompatibility to a parthenogenesis-inducing lifestyle, and is required for reproduction in the Trichogramma host it infects. We hypothesize that the large number of coding frame truncations has accompanied the change in reproductive mode of the wTpre strain. PMID:27194801

  17. Comparative Genomics of a Parthenogenesis-Inducing Wolbachia Symbiont.

    PubMed

    Lindsey, Amelia R I; Werren, John H; Richards, Stephen; Stouthamer, Richard

    2016-07-07

    Wolbachia is an intracellular symbiont of invertebrates responsible for inducing a wide variety of phenotypes in its host. These host-Wolbachia relationships span the continuum from reproductive parasitism to obligate mutualism, and provide a unique system to study genomic changes associated with the evolution of symbiosis. We present the genome sequence from a parthenogenesis-inducing Wolbachia strain (wTpre) infecting the minute parasitoid wasp Trichogramma pretiosum The wTpre genome is the most complete parthenogenesis-inducing Wolbachia genome available to date. We used comparative genomics across 16 Wolbachia strains, representing five supergroups, to identify a core Wolbachia genome of 496 sets of orthologous genes. Only 14 of these sets are unique to Wolbachia when compared to other bacteria from the Rickettsiales. We show that the B supergroup of Wolbachia, of which wTpre is a member, contains a significantly higher number of ankyrin repeat-containing genes than other supergroups. In the wTpre genome, there is evidence for truncation of the protein coding sequences in 20% of ORFs, mostly as a result of frameshift mutations. The wTpre strain represents a conversion from cytoplasmic incompatibility to a parthenogenesis-inducing lifestyle, and is required for reproduction in the Trichogramma host it infects. We hypothesize that the large number of coding frame truncations has accompanied the change in reproductive mode of the wTpre strain. Copyright © 2016 Lindsey et al.

  18. The intriguing complexity of parthenogenesis inheritance in Pilosella rubra (Asteraceae, Lactuceae).

    PubMed

    Rosenbaumová, Radka; Krahulcová, Anna; Krahulec, František

    2012-09-01

    Neither the genetic basis nor the inheritance of apomixis is fully understood in plants. The present study is focused on the inheritance of parthenogenesis, one of the basic elements of apomixis, in Pilosella (Asteraceae). A complex pattern of inheritance was recorded in the segregating F(1) progeny recovered from reciprocal crosses between the facultatively apomictic hexaploid P. rubra and the sexual tetraploid P. officinarum. Although both female and male reduced gametes of P. rubra transmitted parthenogenesis at the same rate in the reciprocal crosses, the resulting segregating F(1) progeny inherited parthenogenesis at different rates. The actual transmission rates of parthenogenesis were significantly correlated with the mode of origin of the respective F(1) progeny class. The inheritance of parthenogenesis was significantly reduced in F(1) n + n hybrid progeny from the cross where parthenogenesis was transmitted by female gametes. In F(1) n + 0 polyhaploid progeny from the same cross, however, the transmission rate of parthenogenesis was high; all fertile polyhaploids were parthenogenetic. It appeared that reduced female gametes transmitting parthenogenesis preferentially developed parthenogenetically and only rarely were fertilized in P. rubra. The fact that the determinant for parthenogenesis acts gametophytically in Pilosella and the precocious embryogenesis in parthenogenesis-transmitting megagametophytes was suggested as the most probable explanations for this observation. Furthermore, we observed the different expression of complete apomixis in the non-segregating F(1) 2n + n hybrids as compared to their apomictic maternal parent P. rubra. We suggest that this difference is a result of unspecified interactions between the parental genomes.

  19. Geographically weighted regression as a generalized Wombling to detect barriers to gene flow.

    PubMed

    Diniz-Filho, José Alexandre Felizola; Soares, Thannya Nascimento; de Campos Telles, Mariana Pires

    2016-08-01

    Barriers to gene flow play an important role in structuring populations, especially in human-modified landscapes, and several methods have been proposed to detect such barriers. However, most applications of these methods require a relative large number of individuals or populations distributed in space, connected by vertices from Delaunay or Gabriel networks. Here we show, using both simulated and empirical data, a new application of geographically weighted regression (GWR) to detect such barriers, modeling the genetic variation as a "local" linear function of geographic coordinates (latitude and longitude). In the GWR, standard regression statistics, such as R(2) and slopes, are estimated for each sampling unit and thus are mapped. Peaks in these local statistics are then expected close to the barriers if genetic discontinuities exist, capturing a higher rate of population differentiation among neighboring populations. Isolation-by-Distance simulations on a longitudinally warped lattice revealed that higher local slopes from GWR coincide with the barrier detected with Monmonier algorithm. Even with a relatively small effect of the barrier, the power of local GWR in detecting the east-west barriers was higher than 95 %. We also analyzed empirical data of genetic differentiation among tree populations of Dipteryx alata and Eugenia dysenterica Brazilian Cerrado. GWR was applied to the principal coordinate of the pairwise FST matrix based on microsatellite loci. In both simulated and empirical data, the GWR results were consistent with discontinuities detected by Monmonier algorithm, as well as with previous explanations for the spatial patterns of genetic differentiation for the two species. Our analyses reveal how this new application of GWR can viewed as a generalized Wombling in a continuous space and be a useful approach to detect barriers and discontinuities to gene flow.

  20. Annually recurring parthenogenesis in a zebra shark Stegostoma fasciatum.

    PubMed

    Robinson, D P; Baverstock, W; Al-Jaru, A; Hyland, K; Khazanehdari, K A

    2011-11-01

    A zebra shark, Stegostoma fasciatum, held in captivity at the Burj Al Arab aquarium, produced embryos and pups in the absence of a male. A total of 15 pups were produced from eggs laid within the aquarium over a period of four consecutive years commencing 2007. Parthenogenesis was confirmed through DNA analysis for three pups sampled during the first two consecutive egg cycles and is presumed to be the method of reproduction responsible thereafter. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

  1. Thelytokous parthenogenesis in the damselfly Ischnura hastata (Odonata, Coenagrionidae): genetic mechanisms and lack of bacterial infection.

    PubMed

    Lorenzo-Carballa, M O; Cordero-Rivera, A

    2009-11-01

    Thelytokous parthenogenesis, the production of female-only offspring from unfertilized eggs, has been described in all the insect orders, but is a rare phenomenon in the Odonata (dragonflies and damselflies). The only-known case of parthenogenesis in this group is the North American damselfly species Ischnura hastata, which has parthenogenetic populations in the Azores Islands. Here, we present for the first time the results of laboratory rearing, which showed parthenogenetic reproduction in the Azorean I. hastata populations. In an attempt to understand how parthenogenesis could have evolved in this species, we first determined the genetic mode of parthenogenesis by analysing the genotype of parthenogenetic females and their offspring at three polymorphic microsatellite loci. In addition, we used polymerase chain reaction amplification to test whether parthenogenesis in I. hastata could be bacterially induced. Our data indicate that thelytoky is achieved through an (at least functionally) apomictic mechanism and that parthenogenesis is not caused by endosymbionts. Finally, we discuss possible routes to parthenogenetic reproduction, as well as the evolutionary implications of this type of parthenogenesis.

  2. The relationship of incubational egg weight loss with parthenogenesis in Chinese Painted quail (Coturnix chinensis).

    PubMed

    Wells, J B; Parker, H M; Kiess, A S; McDaniel, C D

    2012-01-01

    Parthenogenesis, embryonic development of an unfertilized egg, has been studied extensively in turkeys. Recently it has been revealed that parthenogenesis also occurs in Chinese Painted quail, and the percentage of eggs exhibiting parthenogenesis is negatively correlated with clutch sequence position. In broiler breeders, it has been reported that the first egg of a clutch sequence loses less egg weight during incubation than subsequent eggs. Because the incidence of parthenogenesis is greater and egg weight loss is less in the first egg of a clutch sequence, it is possible that egg weight loss is less in parthenogenetic eggs. Therefore, the objective of this study was to determine if a relationship exists between egg weight loss (a measure of eggshell quality) and parthenogenesis. Daily, individual eggs were collected and labeled. To determine egg weight loss, eggs were weighed before setting and then again after 10 d of incubation. Eggs were stored for 0 to 3 d at 20°C and incubated at 37.5°C. Pearson correlation coefficients were used to determine if relationships existed between egg weight loss and average incidence of parthenogenesis, parthenogen size, egg storage, and average clutch sequence position for all hens examined (157) as well as only for hens that exhibited parthenogenesis (102). The percentage of egg weight loss was negatively correlated with the incidence of parthenogenetic eggs and parthenogen size. However, the percentage of egg weight loss was positively correlated with average clutch position. In conclusion, it appears that eggshell quality possibly influences the incidence of parthenogenesis in Chinese Painted quail eggs because as the percentage of egg weight loss decreases, the incidence of parthenogenesis increases.

  3. Parental sex effect of parthenogenesis on progeny production and performance of Chinese Painted Quail (Coturnix chinensis).

    PubMed

    Ramachandran, R; Nascimento Dos Santos, M; Parker, H M; McDaniel, C D

    2018-06-01

    Embryonic development of an unfertilized egg, parthenogenesis, is known to occur in Chinese Painted quail. However, selection for parthenogenesis in both the dam and sire leads to a reduction in hatchability following mating. Therefore, the objective of this study was to determine if selection for parthenogenesis in the dam, sire, or both also impact their progeny performance. There were 2 lines of birds used in this trial: 1 line selected for parthenogenesis and 1 line not selected for parthenogenesis (control) yielding breeding pairs as follows: control dams + control sires (CC), control dams + parthenogenetic sires (CP), parthenogenetic dams + control sires (PC), and parthenogenetic dams + parthenogenetic sires (PP). For all progeny, a dam line main effect revealed that the parthenogenetic line dams had heavier offspring hatch weight and 4 wk body weight as well as higher 1st wk chick mortality versus control line dams. However, control line dams had the highest 4th wk chick mortality versus parthenogenetic line dams. In female virgin progeny, a dam by sire interaction revealed that PP, PC, and CP had the heaviest 1st egg in the clutch position versus CC. Also, eggs from PP had the highest number of eggs and the most female progeny exhibiting parthenogenesis versus CC. There was a linear increase in egg weight as clutch position increased for progeny from PP and CC yet a linear decline for CP. In conclusion, it appears that both the dam and sire selected for parthenogenesis impact progeny performance as parthenogenetic dams and sires additively contribute to the degree of parthenogenesis exhibited by virgin female progeny. Moreover, because parthenogenesis is known to exist in the modern poultry industry, even the accidental selection of the parthenogenetic trait in either males or females could have a negative impact on overall chick production and performance. Published by Elsevier Inc.

  4. Hybridogenesis through thelytokous parthenogenesis in two Cataglyphis desert ants.

    PubMed

    Eyer, P A; Leniaud, L; Darras, H; Aron, S

    2013-02-01

    Hybridogenesis is a sexual reproductive system, whereby parents from different genetic origin hybridize. Both the maternal and paternal genomes are expressed in somatic tissues, but the paternal genome is systematically excluded from the germ line, which is therefore purely maternal. Recently, a unique case of hybridogenesis at a social level was reported in the desert ant Cataglyphis hispanica. All workers are sexually produced hybridogens, whereas sexual forms (new queens and males) are produced by queens through parthenogenesis. Thus, only maternal genes are perpetuated across generations. Here, we show that such an unusual reproductive strategy also evolved in two other species of Cataglyphis belonging to the same phylogenetic group, Cataglyphis velox and Cataglyphis mauritanica. In both species, queens mate exclusively with males originating from a different genetic lineage than their own to produce hybrid workers, while they use parthenogenesis to produce the male and female reproductive castes. In contrast to single-queen colonies of C. hispanica, colonies of C. velox and C. mauritanica are headed by several queens. Most queens within colonies share the same multilocus genotype and never transmit their mates' alleles to the reproductive castes. Social hybridogenesis in the desert ants has direct consequences on the genetic variability of populations and on caste determination. We also discuss the maintenance of this reproductive strategy within the genus Cataglyphis. © 2012 Blackwell Publishing Ltd.

  5. Positive feedback in the transition from sexual reproduction to parthenogenesis

    PubMed Central

    Schwander, Tanja; Vuilleumier, Séverine; Dubman, Janie; Crespi, Bernard J.

    2010-01-01

    Understanding how new phenotypes evolve is challenging because intermediate stages in transitions from ancestral to derived phenotypes often remain elusive. Here we describe and evaluate a new mechanism facilitating the transition from sexual reproduction to parthenogenesis. In many sexually reproducing species, a small proportion of unfertilized eggs can hatch spontaneously (‘tychoparthenogenesis’) and develop into females. Using an analytical model, we show that if females are mate-limited, tychoparthenogenesis can result in the loss of males through a positive feedback mechanism whereby tychoparthenogenesis generates female-biased sex ratios and increasing mate limitation. As a result, the strength of selection for tychoparthenogenesis increases in concert with the proportion of tychoparthenogenetic offspring in the sexual population. We then tested the hypothesis that mate limitation selects for tychoparthenogenesis and generates female-biased sex ratios, using data from natural populations of sexually reproducing Timema stick insects. Across 41 populations, both the tychoparthenogenesis rates and the proportions of females increased exponentially as the density of individuals decreased, consistent with the idea that low densities of individuals result in mate limitation and selection for reproductive insurance through tychoparthenogenesis. Our model and data from Timema populations provide evidence for a simple mechanism through which parthenogenesis can evolve rapidly in a sexual population. PMID:20071382

  6. Positive feedback in the transition from sexual reproduction to parthenogenesis.

    PubMed

    Schwander, Tanja; Vuilleumier, Séverine; Dubman, Janie; Crespi, Bernard J

    2010-05-07

    Understanding how new phenotypes evolve is challenging because intermediate stages in transitions from ancestral to derived phenotypes often remain elusive. Here we describe and evaluate a new mechanism facilitating the transition from sexual reproduction to parthenogenesis. In many sexually reproducing species, a small proportion of unfertilized eggs can hatch spontaneously ('tychoparthenogenesis') and develop into females. Using an analytical model, we show that if females are mate-limited, tychoparthenogenesis can result in the loss of males through a positive feedback mechanism whereby tychoparthenogenesis generates female-biased sex ratios and increasing mate limitation. As a result, the strength of selection for tychoparthenogenesis increases in concert with the proportion of tychoparthenogenetic offspring in the sexual population. We then tested the hypothesis that mate limitation selects for tychoparthenogenesis and generates female-biased sex ratios, using data from natural populations of sexually reproducing Timema stick insects. Across 41 populations, both the tychoparthenogenesis rates and the proportions of females increased exponentially as the density of individuals decreased, consistent with the idea that low densities of individuals result in mate limitation and selection for reproductive insurance through tychoparthenogenesis. Our model and data from Timema populations provide evidence for a simple mechanism through which parthenogenesis can evolve rapidly in a sexual population.

  7. Cyclical parthenogenesis and viviparity in aphids as evolutionary novelties.

    PubMed

    Davis, Gregory K

    2012-09-01

    Evolutionary novelties represent challenges to biologists, particularly those who would like to understand the developmental and genetic changes responsible for their appearance. Most modern aphids possess two apparent evolutionary novelties: cyclical parthenogenesis (a life cycle with both sexual and asexual phases) and viviparity (internal development and live birth of progeny) in their asexual phase. Here I discuss the evolution of these apparent novelties from a developmental standpoint. Although a full understanding of the evolution of cyclical parthenogenesis and viviparity in aphids can seem a daunting task, these complex transitions can at least be broken down into a handful of steps. I argue that these should include the following: a differentiation of two developmentally distinct oocytes; de novo synthesis of centrosomes and modification of meiosis during asexual oogenesis; a loss or bypass of any cell cycle arrest and changes in key developmental events during viviparous oogenesis; and a change in how mothers specify the sexual vs. asexual fates of their progeny. Grappling with the nature of such steps and the order in which they occurred ought to increase our understanding and reduce the apparent novelty of complex evolutionary transitions. © 2012 Wiley Periodicals, Inc.

  8. General practitioner (family physician) workforce in Australia: comparing geographic data from surveys, a mailing list and medicare

    PubMed Central

    2013-01-01

    Background Good quality spatial data on Family Physicians or General Practitioners (GPs) are key to accurately measuring geographic access to primary health care. The validity of computed associations between health outcomes and measures of GP access such as GP density is contingent on geographical data quality. This is especially true in rural and remote areas, where GPs are often small in number and geographically dispersed. However, there has been limited effort in assessing the quality of nationally comprehensive, geographically explicit, GP datasets in Australia or elsewhere. Our objective is to assess the extent of association or agreement between different spatially explicit nationwide GP workforce datasets in Australia. This is important since disagreement would imply differential relationships with primary healthcare relevant outcomes with different datasets. We also seek to enumerate these associations across categories of rurality or remoteness. Method We compute correlations of GP headcounts and workload contributions between four different datasets at two different geographical scales, across varying levels of rurality and remoteness. Results The datasets are in general agreement with each other at two different scales. Small numbers of absolute headcounts, with relatively larger fractions of locum GPs in rural areas cause unstable statistical estimates and divergences between datasets. Conclusion In the Australian context, many of the available geographic GP workforce datasets may be used for evaluating valid associations with health outcomes. However, caution must be exercised in interpreting associations between GP headcounts or workloads and outcomes in rural and remote areas. The methods used in these analyses may be replicated in other locales with multiple GP or physician datasets. PMID:24005003

  9. Multiple births by a captive swellshark Cephaloscyllium ventriosum via facultative parthenogenesis.

    PubMed

    Feldheim, K A; Clews, A; Henningsen, A; Todorov, L; McDermott, C; Meyers, M; Bradley, J; Pulver, A; Anderson, E; Marshall, A

    2017-03-01

    Using a novel set of 12 microsatellites, a captive, adult female swellshark Cephaloscyllium ventriosum that produced five pups via parthenogenesis is described; naturally occurring parthenogenesis has been observed in every vertebrate class with the exception of mammals. As demonstrated in this study, a captive environment is ideal for long-term monitoring of animals under controlled conditions, and easily allows the detection of particular facets of their biology. © 2016 The Fisheries Society of the British Isles.

  10. Parthenogenesis in a Brazilian rainbow boa (Epicrates cenchria cenchria).

    PubMed

    Kinney, Matthew E; Wack, Raymund F; Grahn, Robert A; Lyons, Leslie

    2013-03-01

    A 22-year-old captive Brazilian rainbow boa (Epicrates cenchria cenchria) gave birth to four offspring after being housed with a vasectomized male. Sexual reproduction as a result of failed prior vasectomy, recanalization of the vas deferens, or prolonged sperm storage was ruled out using the clinical history, histopathology, and gross necropsy. Short tandem repeat (STR) DNA markers were genotyped in the male, female, and four offspring. None of the offspring possessed a diagnostic STR allele present in the potential sire. In addition, all offspring were homozygous at each STR locus evaluated, supporting parthenogenetic reproduction. This is the first report of parthenogenesis in a Brazilian rainbow boa and has implications for the conservation of reptiles maintained in captive breeding programs. © 2012 Wiley Periodicals, Inc.

  11. Crosses prior to parthenogenesis explain the current genetic diversity of tropical plant-parasitic Meloidogyne species (Nematoda: Tylenchida).

    PubMed

    Fargette, Mireille; Berthier, Karine; Richaud, Myriam; Lollier, Virginie; Franck, Pierre; Hernandez, Adan; Frutos, Roger

    2010-08-01

    The tropical and subtropical parthenogenetic plant-parasitic nematodes Meloidogyne are polyphagous major agricultural pests. Implementing proper pest management approaches requires a good understanding of mechanisms, population structure, evolutionary patterns and species identification. A comparative analysis of the mitochondrial vs nuclear diversity was conducted on a selected set of Meloidogyne lines from various geographic origins. Mitochondrial co2-16S sequences and AFLP markers of total DNA were applied because of their ability to evidence discrete genetic variation between closely related isolates. Several distinct maternal lineages were present, now associated with different genetic backgrounds. Relative discordances were found when comparing mitochondrial and nuclear diversity patterns. These patterns are most likely related to crosses within one ancestral genetic pool, followed by the establishment of parthenogenesis. In this case, they mirror the genetic backgrounds of the original individuals. Another aspect could be that species emergence was recent or on process from this original genetic pool and that the relatively short time elapsed since then and before parthenogenesis settlement did not allow for lineage sorting. This could also be compatible with the hypothesis of hybrids between closely related species. This genetic pool would correspond to a species as defined by the species interbreeding concept, but also including the grey area of species boundaries. This complex process has implications on the way genotypic and phenotypic diversity should be addressed. The phenotype of parthenogenetic lines is at least for part determined by the ancestral amphimictic genetic background. A direct consequence is, therefore, in terms of risk management, the limited confidence one can have on the direct association of an agronomic threat to a simple typing or species delineation. Risk management strategies and tools must thus consider this complexity when

  12. Utilisation of general practitioner services by socio-economic disadvantage and geographic remoteness.

    PubMed

    Turrell, Gavin; Oldenburg, Brian F; Harris, Elizabeth; Jolley, Damien

    2004-04-01

    To examine the association between socio-economic status (SES) and GP utilisation across Statistical Local Areas (SLAs) that differed in their geographic remoteness, and to assess whether Indigenous status and GP availability modified the association. Retrospective analysis of Medicare data for all unreferred GP consultations (1996/97) for 952 SLAs comprising the six Australian States. Geographic remoteness was ascertained using the Area Remoteness Index of Australia (ARIA), and SES was measured by grouping SLAs into tertiles based on their Index of Relative Socioeconomic Disadvantage score. Age/sex standardised rates of GP utilisation for each SLA. In SLAs classified as 'highly accessible', rates of GP use were 10.8% higher (95% CI 5.7-16.0) in the most socio-economically disadvantaged tertile after adjustment for Indigenous status and GP availability. A very different pattern of GP utilsation was found in 'remote/very remote' SLAs. After adjustment, rates of GP use in the most socio-economically disadvantaged tertile were 25.3% lower (95% CI 5.9-40.7) than in the most advantaged tertile. People in socio-economically disadvantaged metropolitan SLAs have higher rates of GP utilisation, as would be expected due to their poorer health. This is not true for people living in disadvantaged remote/very remote SLAs: in these areas, those most in need of GP services are least likely to receive them. Australia may lay claim to having a primary health care system that provides universal coverage, but we are still some way from having a system that is economically and geographically accessible to all.

  13. The relationship of parthenogenesis in virgin Chinese Painted quail (Coturnix chinensis) hens with embryonic mortality and hatchability following mating.

    PubMed

    Parker, H M; Kiess, A S; Robertson, M L; Wells, J B; McDaniel, C D

    2012-06-01

    Unfertilized chicken, turkey, and quail eggs are capable of developing embryos by parthenogenesis. However, it is unknown if the physiological mechanisms regulating parthenogenesis in virgin hens may actually work against fertilization, embryonic development, and hatchability of eggs from these same hens following mating. Additionally, because most parthenogenic development closely resembles early embryonic mortality in fertilized eggs during the first 2 to 3 d of incubation, it is possible that many unhatched eggs classified as containing early embryonic mortality may actually be unfertilized eggs that contain parthenogens. Therefore, the objective of this study was to examine the relationship of parthenogenesis before mating with embryonic development and hatchability characteristics after mating. Based upon their ability to produce unfertilized eggs that contain parthenogens, 372 virgin Chinese Painted quail hens were divided into 7 groups, according to their incidence of parthenogenesis: 0, 10, 20, 30, 40, 50, and greater than 50% parthenogenesis. Males were then placed with these hens so that fertility, embryonic mortality, and hatchability could be evaluated for each hen. Hatchability of eggs set, hatchability of fertile eggs, and late embryonic mortality declined dramatically as the incidence of parthenogenesis increased. On the other hand, early embryonic mortality increased as parthenogenesis increased. Fertility was not different across the 7 parthenogenesis hen groups, perhaps because unfertilized eggs that exhibited parthenogenesis resembled and were therefore classified as early embryonic mortality. In conclusion, virgin quail hens that exhibit parthenogenesis appear to have impaired embryonic development and hatchability following mating. Additional sperm-egg interaction and embryonic research is needed to determine if a large portion of the early embryonic mortality experienced by mated hens that exhibit parthenogenesis as virgin hens is in fact

  14. [Geographical coverage of the Mexican Healthcare System and a spatial analysis of utilization of its General Hospitals in 1998].

    PubMed

    Hernández-Avila, Juan E; Rodríguez, Mario H; Rodríguez, Norma E; Santos, René; Morales, Evangelina; Cruz, Carlos; Sepúlveda-Amor, Jaime

    2002-01-01

    To describe the geographical coverage of the Mexican Healthcare System (MHS) services and to assess the utilization of its General Hospitals. A Geographic Information System (GIS) was used to include sociodemographic data by locality, the geographical location of all MHS healthcare services, and data on hospital discharge records. A maximum likelihood estimation model was developed to assess the utilization levels of 217 MHS General Hospitals. The model included data on human resources, additional infrastructure, and the population within a 25 km radius. In 1998, 10,806 localities with 72 million inhabitants had at least one public healthcare unit, and 97.2% of the population lived within 50 km of a healthcare unit; however, over 18 million people lived in rural localities without a healthcare unit. The mean annual hospital occupation rate was 48.5 +/- 28.5 per 100 bed/years, with high variability within and between states. Hospital occupation was significantly associated with the number of physicians in the unit, and in the Mexican Institute of Social Security units utilization was associated with additional health infrastructure, and with the population's poverty index. GIS analysis allows improved estimation of the coverage and utilization of MHS hospitals.

  15. Does a parthenogenesis-inducing Wolbachia induce vestigial cytoplasmic incompatibility?

    NASA Astrophysics Data System (ADS)

    Kraaijeveld, Ken; Reumer, Barbara M.; Mouton, Laurence; Kremer, Natacha; Vavre, Fabrice; van Alphen, Jacques J. M.

    2011-03-01

    Wolbachia is a maternally inherited bacterium that manipulates the reproduction of its host. Recent studies have shown that male-killing strains can induce cytoplasmic incompatibility (CI) when introgressed into a resistant host. Phylogenetic studies suggest that transitions between CI and other Wolbachia phenotypes have also occurred frequently, raising the possibility that latent CI may be widespread among Wolbachia. Here, we investigate whether a parthenogenesis-inducing Wolbachia strain can also induce CI. Parthenogenetic females of the parasitoid wasp Asobara japonica regularly produce a small number of males that may be either infected or not. Uninfected males were further obtained through removal of the Wolbachia using antibiotics and from a naturally uninfected strain. Uninfected females that had mated with infected males produced a slightly, but significantly more male-biased sex ratio than uninfected females that had mated with uninfected males. This effect was strongest in females that mated with males that had a relatively high Wolbachia titer. Quantitative PCR indicated that infected males did not show higher ratios of nuclear versus mitochondrial DNA content. Wolbachia therefore does not cause diploidization of cells in infected males. While these results are consistent with CI, other alternatives such as production of abnormal sperm by infected males cannot be completely ruled out. Overall, the effect was very small (9%), suggesting that if CI is involved it may have degenerated through the accumulation of mutations.

  16. Effects of complex life cycles on genetic diversity: cyclical parthenogenesis.

    PubMed

    Rouger, R; Reichel, K; Malrieu, F; Masson, J P; Stoeckel, S

    2016-11-01

    Neutral patterns of population genetic diversity in species with complex life cycles are difficult to anticipate. Cyclical parthenogenesis (CP), in which organisms undergo several rounds of clonal reproduction followed by a sexual event, is one such life cycle. Many species, including crop pests (aphids), human parasites (trematodes) or models used in evolutionary science (Daphnia), are cyclical parthenogens. It is therefore crucial to understand the impact of such a life cycle on neutral genetic diversity. In this paper, we describe distributions of genetic diversity under conditions of CP with various clonal phase lengths. Using a Markov chain model of CP for a single locus and individual-based simulations for two loci, our analysis first demonstrates that strong departures from full sexuality are observed after only a few generations of clonality. The convergence towards predictions made under conditions of full clonality during the clonal phase depends on the balance between mutations and genetic drift. Second, the sexual event of CP usually resets the genetic diversity at a single locus towards predictions made under full sexuality. However, this single recombination event is insufficient to reshuffle gametic phases towards full-sexuality predictions. Finally, for similar levels of clonality, CP and acyclic partial clonality (wherein a fixed proportion of individuals are clonally produced within each generation) differentially affect the distribution of genetic diversity. Overall, this work provides solid predictions of neutral genetic diversity that may serve as a null model in detecting the action of common evolutionary or demographic processes in cyclical parthenogens (for example, selection or bottlenecks).

  17. Molecular evidence for the first records of facultative parthenogenesis in elapid snakes

    PubMed Central

    Sanders, K. L.

    2018-01-01

    Parthenogenesis is a form of asexual reproduction by which embryos develop from unfertilized eggs. Parthenogenesis occurs in reptiles; however, it is not yet known to occur in the widespread elapid snakes (Elapidae), which include well-known taxa such as cobras, mambas, taipans and sea snakes. Here, we describe the production of viable parthenogens in two species of Australo-Papuan elapids with divergent reproductive modes: the oviparous coastal/Papuan taipan (Oxyuranus scutellatus) and the viviparous southern death adder (Acanthophis antarcticus). Analyses of nuclear SNP data excluded paternity for putative fathers and convincingly demonstrated asexual reproduction, thus representing the first evidence of facultative parthenogenesis in Elapidae. Our finding has broad implications for understanding the evolution of reproductive diversity in snakes, as well as managing the conservation of genetic diversity in wild and captive populations. PMID:29515892

  18. Molecular evidence for the first records of facultative parthenogenesis in elapid snakes.

    PubMed

    Allen, L; Sanders, K L; Thomson, V A

    2018-02-01

    Parthenogenesis is a form of asexual reproduction by which embryos develop from unfertilized eggs. Parthenogenesis occurs in reptiles; however, it is not yet known to occur in the widespread elapid snakes (Elapidae), which include well-known taxa such as cobras, mambas, taipans and sea snakes. Here, we describe the production of viable parthenogens in two species of Australo-Papuan elapids with divergent reproductive modes: the oviparous coastal/Papuan taipan ( Oxyuranus scutellatus ) and the viviparous southern death adder ( Acanthophis antarcticus ). Analyses of nuclear SNP data excluded paternity for putative fathers and convincingly demonstrated asexual reproduction, thus representing the first evidence of facultative parthenogenesis in Elapidae. Our finding has broad implications for understanding the evolution of reproductive diversity in snakes, as well as managing the conservation of genetic diversity in wild and captive populations.

  19. Meiosis genes in Daphnia pulex and the role of parthenogenesis in genome evolution.

    PubMed

    Schurko, Andrew M; Logsdon, John M; Eads, Brian D

    2009-04-21

    Thousands of parthenogenetic animal species have been described and cytogenetic manifestations of this reproductive mode are well known. However, little is understood about the molecular determinants of parthenogenesis. The Daphnia pulex genome must contain the molecular machinery for different reproductive modes: sexual (both male and female meiosis) and parthenogenetic (which is either cyclical or obligate). This feature makes D. pulex an ideal model to investigate the genetic basis of parthenogenesis and its consequences for gene and genome evolution. Here we describe the inventory of meiotic genes and their expression patterns during meiotic and parthenogenetic reproduction to help address whether parthenogenesis uses existing meiotic and mitotic machinery, or whether novel processes may be involved. We report an inventory of 130 homologs representing over 40 genes encoding proteins with diverse roles in meiotic processes in the genome of D. pulex. Many genes involved in cell cycle regulation and sister chromatid cohesion are characterized by expansions in copy number. In contrast, most genes involved in DNA replication and homologous recombination are present as single copies. Notably, RECQ2 (which suppresses homologous recombination) is present in multiple copies while DMC1 is the only gene in our inventory that is absent in the Daphnia genome. Expression patterns for 44 gene copies were similar during meiosis versus parthenogenesis, although several genes displayed marked differences in expression level in germline and somatic tissues. We propose that expansions in meiotic gene families in D. pulex may be associated with parthenogenesis. Taking into account our findings, we provide a mechanistic model of parthenogenesis, highlighting steps that must differ from meiosis including sister chromatid cohesion and kinetochore attachment.

  20. Meiosis genes in Daphnia pulex and the role of parthenogenesis in genome evolution

    PubMed Central

    Schurko, Andrew M; Logsdon, John M; Eads, Brian D

    2009-01-01

    Background Thousands of parthenogenetic animal species have been described and cytogenetic manifestations of this reproductive mode are well known. However, little is understood about the molecular determinants of parthenogenesis. The Daphnia pulex genome must contain the molecular machinery for different reproductive modes: sexual (both male and female meiosis) and parthenogenetic (which is either cyclical or obligate). This feature makes D. pulex an ideal model to investigate the genetic basis of parthenogenesis and its consequences for gene and genome evolution. Here we describe the inventory of meiotic genes and their expression patterns during meiotic and parthenogenetic reproduction to help address whether parthenogenesis uses existing meiotic and mitotic machinery, or whether novel processes may be involved. Results We report an inventory of 130 homologs representing over 40 genes encoding proteins with diverse roles in meiotic processes in the genome of D. pulex. Many genes involved in cell cycle regulation and sister chromatid cohesion are characterized by expansions in copy number. In contrast, most genes involved in DNA replication and homologous recombination are present as single copies. Notably, RECQ2 (which suppresses homologous recombination) is present in multiple copies while DMC1 is the only gene in our inventory that is absent in the Daphnia genome. Expression patterns for 44 gene copies were similar during meiosis versus parthenogenesis, although several genes displayed marked differences in expression level in germline and somatic tissues. Conclusion We propose that expansions in meiotic gene families in D. pulex may be associated with parthenogenesis. Taking into account our findings, we provide a mechanistic model of parthenogenesis, highlighting steps that must differ from meiosis including sister chromatid cohesion and kinetochore attachment. PMID:19383157

  1. Adding Temporal Characteristics to Geographical Schemata and Instances: A General Framework

    NASA Astrophysics Data System (ADS)

    Ota, Morishige

    2018-05-01

    This paper proposes the temporal general feature model (TGFM) as a meta-model for application schemata representing changes of real-world phenomena. It is not very easy to determine history directly from the current application schemata, even if the revision notes are attached to the specification. To solve this problem, the rules for description of the succession between previous and posterior components are added to the general feature model, thus resulting in TGFM. After discussing the concepts associated with the new model, simple examples of application schemata are presented as instances of TGFM. Descriptors for changing properties, the succession of changing properties in moving features, and the succession of features and associations are introduced. The modeling methods proposed in this paper will contribute to the acquisition of consistent and reliable temporal geospatial data.

  2. Effects of complex life cycles on genetic diversity: cyclical parthenogenesis

    PubMed Central

    Rouger, R; Reichel, K; Malrieu, F; Masson, J P; Stoeckel, S

    2016-01-01

    Neutral patterns of population genetic diversity in species with complex life cycles are difficult to anticipate. Cyclical parthenogenesis (CP), in which organisms undergo several rounds of clonal reproduction followed by a sexual event, is one such life cycle. Many species, including crop pests (aphids), human parasites (trematodes) or models used in evolutionary science (Daphnia), are cyclical parthenogens. It is therefore crucial to understand the impact of such a life cycle on neutral genetic diversity. In this paper, we describe distributions of genetic diversity under conditions of CP with various clonal phase lengths. Using a Markov chain model of CP for a single locus and individual-based simulations for two loci, our analysis first demonstrates that strong departures from full sexuality are observed after only a few generations of clonality. The convergence towards predictions made under conditions of full clonality during the clonal phase depends on the balance between mutations and genetic drift. Second, the sexual event of CP usually resets the genetic diversity at a single locus towards predictions made under full sexuality. However, this single recombination event is insufficient to reshuffle gametic phases towards full-sexuality predictions. Finally, for similar levels of clonality, CP and acyclic partial clonality (wherein a fixed proportion of individuals are clonally produced within each generation) differentially affect the distribution of genetic diversity. Overall, this work provides solid predictions of neutral genetic diversity that may serve as a null model in detecting the action of common evolutionary or demographic processes in cyclical parthenogens (for example, selection or bottlenecks). PMID:27436524

  3. Geographic Diffusion and Implementation of Acute Care Surgery: An Uneven Solution to the National Emergency General Surgery Crisis.

    PubMed

    Khubchandani, Jasmine A; Ingraham, Angela M; Daniel, Vijaya T; Ayturk, Didem; Kiefe, Catarina I; Santry, Heena P

    2018-02-01

    Owing to lack of adequate emergency care infrastructure and decline in general surgery workforce, the United States faces a crisis in access to emergency general surgery (EGS) care. Acute care surgery (ACS), an organized system of trauma, general surgery, and critical care, is a proposed solution; however, ACS diffusion remains poorly understood. To investigate geographic diffusion of ACS models of care and characterize the communities in which ACS implementation is lagging. A national survey on EGS practices was developed, tested, and administered at all 2811 US acute care hospitals providing EGS to adults between August 2015 and October 2015. Surgeons responsible for EGS coverage at these hospitals were approached. If these surgeons failed to respond to the initial survey implementation, secondary surgeons or chief medical officers at hospitals with only 1 general surgeon were approached. Survey responses on ACS implementation were linked with geocoded hospital data and national census data to determine geographic diffusion of and access to ACS. We measured the distribution of hospitals with ACS models of care vs those without over time (diffusion) and by US counties characterized by sociodemographic characteristics of county residents (access). Survey response rate was 60% (n = 1690); 272 responding hospitals had implemented ACS by 2015, steadily increasing from 34 in 2001 to 125 in 2010. Acute care surgery implementation has not been uniform. Rural regions have limited ACS access, with hospitals in counties with greater than the 75th percentile population having 5.4 times higher odds (95% CI, 1.66-7.35) of implementing ACS than hospitals in counties with less than 25th percentile population. Communities with greater percentages of adults without a college degree also have limited ACS access (OR, 3.43; 95% CI, 1.81-6.48). However, incorporating EGS into ACS models may be a potential equalizer for poor, black, and Hispanic communities. Understanding and

  4. Facultative parthenogenesis validated by DNA analyses in the green anaconda (Eunectes murinus)

    PubMed Central

    Sakata, Shuichi; Hirano, Yuzo; Nitasaka, Eiji; Sakabe, Ai

    2017-01-01

    In reptiles, the mode of reproduction is typically sexual. However, facultative parthenogenesis occurs in some Squamata, such as Komodo dragon (Varanus komodoensis) and Burmese python (Python bivittatus). Here, we report facultative parthenogenesis in the green anaconda (Eunectes murinus). We found two fully developed female neonates and 17 undeveloped eggs in the oviduct of a female anaconda isolated from other individuals for eight years and two months at Ueno Zoo, Japan. To clarify the zygosity of the neonates, we analyzed 18 microsatellite markers of which 16 were informative. We observed only maternal alleles and no paternal alleles for all 16 markers. To examine the possibility of the long-term sperm storage, we estimated allele frequencies in a putative parental stock by genotyping five unrelated founders. If all founders, including the mother, are originated from a single Mendelian population, then the probability that the neonates were produced by sexual reproduction with an unrelated male via long-term sperm storage was infinitesimally small (2.31E-32 per clutch). We also examined samples from two additional offspring that the mother delivered eight years before her death. We consistently observed paternal alleles in these elder offspring, indicating that the mother had switched from sexual reproduction to asexual reproduction during the eight years of isolation. This is the first case of parthenogenesis in Eunectes to be validated by DNA analysis, and suggests that facultative parthenogenesis is widespread in the Boidae. PMID:29236745

  5. Novel microsatellite markers suggest the mechanism of parthenogenesis in Extatosoma tiaratum is automixis with terminal fusion.

    PubMed

    Alavi, Yasaman; van Rooyen, Anthony; Elgar, Mark Adrian; Jones, Therésa Melanie; Weeks, Andrew Raymond

    2018-02-01

    Parthenogenetic reproduction is taxonomically widespread and occurs through various cytological mechanisms, which have different impact on the genetic variation of the offspring. Extatosoma tiaratum is a facultatively parthenogenetic Australian insect (Phasmatodea), in which females oviposit continuously throughout their adult lifespan irrespective of mating. Fertilized eggs produce sons and daughters through sexual reproduction and unfertilized eggs produce female offspring via parthenogenesis. Here, we developed novel microsatellite markers for E. tiaratum and characterized them by genotyping individuals from a natural population. We then used the microsatellite markers to infer the cytological mechanism of parthenogenesis in this species. We found evidence suggesting parthenogenesis in E. tiaratum occurs through automixis with terminal fusion, resulting in substantial loss of microsatellite heterozygosity in the offspring. Loss of microsatellite heterozygosity may be associated with loss of heterozygosity in fitness related loci. The mechanism of parthenogenetic reproduction can therefore affect fitness outcomes and needs to be considered when comparing costs and benefits of sex versus parthenogenesis. © 2016 Institute of Zoology, Chinese Academy of Sciences.

  6. Facultative parthenogenesis validated by DNA analyses in the green anaconda (Eunectes murinus).

    PubMed

    Shibata, Hiroki; Sakata, Shuichi; Hirano, Yuzo; Nitasaka, Eiji; Sakabe, Ai

    2017-01-01

    In reptiles, the mode of reproduction is typically sexual. However, facultative parthenogenesis occurs in some Squamata, such as Komodo dragon (Varanus komodoensis) and Burmese python (Python bivittatus). Here, we report facultative parthenogenesis in the green anaconda (Eunectes murinus). We found two fully developed female neonates and 17 undeveloped eggs in the oviduct of a female anaconda isolated from other individuals for eight years and two months at Ueno Zoo, Japan. To clarify the zygosity of the neonates, we analyzed 18 microsatellite markers of which 16 were informative. We observed only maternal alleles and no paternal alleles for all 16 markers. To examine the possibility of the long-term sperm storage, we estimated allele frequencies in a putative parental stock by genotyping five unrelated founders. If all founders, including the mother, are originated from a single Mendelian population, then the probability that the neonates were produced by sexual reproduction with an unrelated male via long-term sperm storage was infinitesimally small (2.31E-32 per clutch). We also examined samples from two additional offspring that the mother delivered eight years before her death. We consistently observed paternal alleles in these elder offspring, indicating that the mother had switched from sexual reproduction to asexual reproduction during the eight years of isolation. This is the first case of parthenogenesis in Eunectes to be validated by DNA analysis, and suggests that facultative parthenogenesis is widespread in the Boidae.

  7. Effects of gonadotropins on in vitro maturation and of electrical stimulation on parthenogenesis of canine oocytes.

    PubMed

    Kim, B S; Lee, S R; Hyun, B H; Shin, M J; Yoo, D H; Lee, S; Park, Y S; Ha, J H; Ryoo, Z Y

    2010-02-01

    The objective of this study was to determine the effects of gonadotropins on in vitro maturation (IVM) and electrical stimulation on the parthenogenesis of canine oocytes. In experiment I, cumulus oocyte complexes were collected from ovaries at a random phase of the oestrus cycle and cultured on maturation medium treated with hCG or eCG for 48 or 72 h. There were no significant differences in the effects on the metaphase II (MII) rate between the hCG and eCG treatment groups over 48 h (5.4% vs 5.5%). The MII rate in the co-treatment group of hCG and eCG for 48 h was higher than in each hormone treated group (15.5%, p < 0.05). In experiment 2, the parthenogenetic effect on oocyte development, at various electrical field strengths (1.0, 1.5, 2.0 kV/cm DC) for 60 or 80 mus with a single DC pulse after IVM on the co-treatment of hCG and eCG, was examined. The rate of pronuclear formation (37.1%) in electrical activation at 1.5 kV/60 mus without cytochalasin B (CB) was higher than that of oocytes activated in the other groups (p < 0.05). However, we did not observe the cleavage stages. Also, CB did not influence parthenogenesis of canine oocytes. The results showed that the pronucleus formation rate, indicative of the parthenogenesis start point, could be increased by electrical stimulation. Therefore, these results can provide important data for the parthenogenesis of canine oocytes and suggest the probability of parthenogenesis in canines.

  8. A parthenogenesis gene of apomict origin elicits embryo formation from unfertilized eggs in a sexual plant

    PubMed Central

    Conner, Joann A.; Mookkan, Muruganantham; Huo, Heqiang; Chae, Keun; Ozias-Akins, Peggy

    2015-01-01

    Apomixis is a naturally occurring mode of asexual reproduction in flowering plants that results in seed formation without the involvement of meiosis or fertilization of the egg. Seeds formed on an apomictic plant contain offspring genetically identical to the maternal plant. Apomixis has significant potential for preserving hybrid vigor from one generation to the next in highly productive crop plant genotypes. Apomictic Pennisetum/Cenchrus species, members of the Poaceae (grass) family, reproduce by apospory. Apospory is characterized by apomeiosis, the formation of unreduced embryo sacs derived from nucellar cells of the ovary and, by parthenogenesis, the development of the unreduced egg into an embryo without fertilization. In Pennisetum squamulatum (L.) R.Br., apospory segregates as a single dominant locus, the apospory-specific genomic region (ASGR). In this study, we demonstrate that the PsASGR-BABY BOOM-like (PsASGR-BBML) gene is expressed in egg cells before fertilization and can induce parthenogenesis and the production of haploid offspring in transgenic sexual pearl millet. A reduction of PsASGR-BBML expression in apomictic F1 RNAi transgenic plants results in fewer visible parthenogenetic embryos and a reduction of embryo cell number compared with controls. Our results endorse a key role for PsASGR-BBML in parthenogenesis and a newly discovered role for a member of the BBM-like clade of APETALA 2 transcription factors. Induction of parthenogenesis by PsASGR-BBML will be valuable for installing parthenogenesis to synthesize apomixis in crops and will have further application for haploid induction to rapidly obtain homozygous lines for breeding. PMID:26305939

  9. A parthenogenesis gene of apomict origin elicits embryo formation from unfertilized eggs in a sexual plant.

    PubMed

    Conner, Joann A; Mookkan, Muruganantham; Huo, Heqiang; Chae, Keun; Ozias-Akins, Peggy

    2015-09-08

    Apomixis is a naturally occurring mode of asexual reproduction in flowering plants that results in seed formation without the involvement of meiosis or fertilization of the egg. Seeds formed on an apomictic plant contain offspring genetically identical to the maternal plant. Apomixis has significant potential for preserving hybrid vigor from one generation to the next in highly productive crop plant genotypes. Apomictic Pennisetum/Cenchrus species, members of the Poaceae (grass) family, reproduce by apospory. Apospory is characterized by apomeiosis, the formation of unreduced embryo sacs derived from nucellar cells of the ovary and, by parthenogenesis, the development of the unreduced egg into an embryo without fertilization. In Pennisetum squamulatum (L.) R.Br., apospory segregates as a single dominant locus, the apospory-specific genomic region (ASGR). In this study, we demonstrate that the PsASGR-BABY BOOM-like (PsASGR-BBML) gene is expressed in egg cells before fertilization and can induce parthenogenesis and the production of haploid offspring in transgenic sexual pearl millet. A reduction of PsASGR-BBML expression in apomictic F1 RNAi transgenic plants results in fewer visible parthenogenetic embryos and a reduction of embryo cell number compared with controls. Our results endorse a key role for PsASGR-BBML in parthenogenesis and a newly discovered role for a member of the BBM-like clade of APETALA 2 transcription factors. Induction of parthenogenesis by PsASGR-BBML will be valuable for installing parthenogenesis to synthesize apomixis in crops and will have further application for haploid induction to rapidly obtain homozygous lines for breeding.

  10. Integrative taxonomy of root-knot nematodes reveals multiple independent origins of mitotic parthenogenesis

    PubMed Central

    Janssen, Toon; Karssen, Gerrit; Topalović, Olivera; Coyne, Danny; Bert, Wim

    2017-01-01

    During sampling of several Coffea arabica plantations in Tanzania severe root galling, caused by a root-knot nematode was observed. From pure cultures, morphology and morphometrics of juveniles and females matched perfectly with Meloidogyne africana, whereas morphology of the males matched identically with those of Meloidogyne decalineata. Based on their Cox1 sequence, however, the recovered juveniles, females and males were confirmed to belong to the same species, creating a taxonomic conundrum. Adding further to this puzzle, re-examination of M. oteifae type material showed insufficient morphological evidence to maintain its status as a separate species. Consequently, M. decalineata and M. oteifae are synonymized with M. africana, which is herewith redescribed based on results of light and scanning electron microscopy, ribosomal and mitochondrial DNA sequences, isozyme electrophoresis, along with bionomic and cytogenetic features. Multi-gene phylogenetic analysis placed M. africana outside of the three major clades, together with M. coffeicola, M. ichinohei and M. camelliae. This phylogenetic position was confirmed by several morphological features, including cellular structure of the spermatheca, egg mass position, perineal pattern and head shape. Moreover, M. africana was found to be a polyphagous species, demonstrating that “early-branching” Meloidogyne spp. are not as oligophagous as had previously been assumed. Cytogenetic information indicates M. africana (2n = 21) and M. ardenensis (2n = 51–54) to be a triploid mitotic parthenogenetic species, revealing at least four independent origins of mitotic parthenogenesis within the genus Meloidogyne. Furthermore, M. mali (n = 12) was found to reproduce by amphimixis, indicating that amphimictic species with a limited number of chromosomes are widespread in the genus, potentially reflecting the ancestral state of the genus. The wide variation in chromosome numbers and associated changes in reproduction modes

  11. Parthenogenesis in mated Chinese Painted quail (Coturnix chinensis) hens decreases sperm-egg penetration and alters albumen characteristics.

    PubMed

    Santa Rosa, P; Parker, H M; Kiess, A S; McDaniel, C D

    2016-10-15

    Parthenogenesis, embryonic development without fertilization, resembles very early embryonic mortality in fertilized eggs. Also, parthenogenesis alters egg albumen characteristics in virgin Chinese Painted quail hens genetically selected for parthenogenesis (PV). When these PV hens are mated (PM), hatchability is reduced versus control mated (CM) hens that were not genetically selected for parthenogenesis. However, it is unclear if parthenogenesis, which occurs in PM hens, reduces hatchability due to infertility and altered albumen characteristics. Sperm-egg penetration (SEP) holes are indicative of true fertilization and may be useful in identifying if eggs from PM hens exhibit a decrease in fertility versus CM hens. Therefore, the objectives of this study were to determine if parthenogenesis in PM hens (1) decreases SEP, (2) alters albumen characteristics similar to parthenogenesis in eggs from PV hens, and (3) yields albumen characteristics similar to fertilized eggs containing early mortality. Daily, PV and PM eggs were collected, labeled, and incubated for 10 days, then broken out to determine the incidence of parthenogenesis and albumen characteristics. Also daily, fresh PM and CM quail eggs were macroscopically examined to determine if an egg was infertile with no embryonic development, parthenogenetic, or fertile. Each of these eggs was then microscopically examined for SEP. For both PV and PM incubated eggs, parthenogenesis decreased albumen pH, O2, and protein concentrations yet increased Ca(2+) and CO2 concentrations versus eggs with no development. For incubated PM eggs, albumen pH and O2 were lower, yet CO2 was higher for eggs containing parthenogens or early dead embryos versus infertile eggs. For SEP, fresh eggs classified as infertile or parthenogenetic from PM and CM hens had similar SEP holes but only one sixth as many SEP holes as eggs classified as fertilized. Eggs from CM hens had 3.5 times as many SEP holes as PM eggs. In conclusion

  12. SAS macro programs for geographically weighted generalized linear modeling with spatial point data: applications to health research.

    PubMed

    Chen, Vivian Yi-Ju; Yang, Tse-Chuan

    2012-08-01

    An increasing interest in exploring spatial non-stationarity has generated several specialized analytic software programs; however, few of these programs can be integrated natively into a well-developed statistical environment such as SAS. We not only developed a set of SAS macro programs to fill this gap, but also expanded the geographically weighted generalized linear modeling (GWGLM) by integrating the strengths of SAS into the GWGLM framework. Three features distinguish our work. First, the macro programs of this study provide more kernel weighting functions than the existing programs. Second, with our codes the users are able to better specify the bandwidth selection process compared to the capabilities of existing programs. Third, the development of the macro programs is fully embedded in the SAS environment, providing great potential for future exploration of complicated spatially varying coefficient models in other disciplines. We provided three empirical examples to illustrate the use of the SAS macro programs and demonstrated the advantages explained above. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Parthenogenesis and somatic cell nuclear transfer in sheep oocytes using Polscope.

    PubMed

    Nandedkar, Pandit; Chohan, Parul; Patwardhan, Archana; Gaikwad, Santosh; Bhartiya, Deepa

    2009-07-01

    Parthenogenesis and Somatic cell nuclear transfer (SCNT) techniques, offer a unique approach to manipulate the genetic composition of derived human embryonic stem cells - an essential step if the full opportunities for disease modeling, drug discovery or individualized stem cell therapy are to be realized. The present study describes the use of sheep oocytes to acquire expertise and establish methods to reconstruct embryos for obtaining blastocysts before venturing into human SCNT where the oocytes are a very precious starting material. Maturation of sheep eggs in vitro for 20-24 hr resulted in 65% metaphase II (MII) eggs which were either parthenogenetically activated using calcium ionomycin or ethanol or subjected to SCNT using cumulus cell as somatic cell. Sixteen blastocysts were produced by parthenogenetic activation of 350 eggs whereas reconstructed embryos, after SCNT carried out in 139 eggs, progressed only up to morula stage. The procedure of parthenogenesis and SCNT will be useful to generate autologous ES cells using human eggs.

  14. Wolbachia-mediated parthenogenesis in the predatory thrips Franklinothrips vespiformis (Thysanoptera: Insecta).

    PubMed Central

    Arakaki, N.; Miyoshi, T.; Noda, H.

    2001-01-01

    Wolbachia are bacterial endosymbionts in arthropods and filarial nematodes. They cause thelytoky, which is a form of parthenogenesis in which females produce females without males, in hymenopteran insects. Infection of this parthenogenesis-inducing Wolbachia has been restricted to the order Hymenoptera, but was found in another insect order, Thysanoptera. A parthenogenetic colony of a predatory thrips Franklinothrips vespiformis (Aeolothripidae) possessed B-group Wolbachia. Male progeny were produced from this thrips by heat and tetracycline treatments. Males produced motile sperm, which were transferred to the female spermatheca by mating. However, the mating did not affect the sex ratios of the next generation, suggesting that the sperm do not fertilize the eggs. PMID:11375084

  15. The Australian scincid lizard Menetia greyii: a new instance of widespread vertebrate parthenogenesis.

    PubMed

    Adams, Mark; Foster, Ralph; Hutchinson, Mark N; Hutchinson, Rhonda G; Donnellan, Steve C

    2003-11-01

    Molecular data derived from allozymes and mitochondrial nucleotide sequences, in combination with karyotypes, sex ratios, and inheritance data, have revealed the widespread Australian lizard Menetia greyii to be a complex of sexual and triploid unisexual taxa. Three sexual species, three presumed parthenogenetic lineages, and one animal of uncertain status were detected amongst 145 animals examined from south-central Australia, an area representing less than one-seventh of the total distribution of the complex. Parthenogenesis appears to have originated via interspecific hybridization, although presumed sexual ancestors could only be identified in two cases. The allozyme and mtDNA data reveal the presence of many distinct clones within the presumed parthenogenetic lineages. This new instance of vertebrate parthenogenesis is a first for the Scincidae and only the second definitive case of unisexuality in an indigenous Australian vertebrate.

  16. [Chromatin in diapause of the silkworm Bombyx mori L.: thermal parthenogenesis and normal development].

    PubMed

    Klimenko, V V; Khaoiuan', Lian

    2012-01-01

    Having used hematoxylin as a stain, some features of silkworm embryo chromatin in diapause have been studied in normal and parthenogenetic development. With found direct correlation between the number of interphase chromatin grains and the number of chromosomes in the nucleus, we examined cell polyploidization in the embryo at diapause stage. Polyploidization by parthenogenesis is not reducible to endomitotic doubling of the chromosome set because it comprises 6n-nuclei. Explanation of more diverse range of polyploid cells in parthenogenesis needs to consider the fusion of cleavage nuclei that is carried out by the cytoplasmic karyogamic mechanism in the absence of fertilization. For the first time on squash preparations, in diapausing embryo, we have identified primary germ cells (PGC) that are characterized by less compact chromatin, especially in the zygotic form of development, a larger size of the nucleus and cytoplasm, and irregular number and size of nucleoli. Evaluation of PGC ploidy in parthenogenesis by calculation of "loose" chromatin grains in diapause is possible and testifies polyploidization in embryo germ-line. This explains the inevitable admixture of tetraploid eggs in diploid parthenoclone grain and its absence in normal development. Cytological method used has revealed a spiral arrangement of chromatin grains on the inner surface of the nucleus at different levels of ploidy.

  17. Sex versus parthenogenesis; immune function in a facultatively parthenogenetic phasmatid (Extatosoma tiaratum).

    PubMed

    Alavi, Yasaman; Elgar, Mark Adrian; Jones, Therésa Melanie

    2017-07-01

    Facultative parthenogenetic species, in which females can alternate between sex and parthenogenesis, are useful models to investigate the costs and benefits of sex and parthenogenesis, an ongoing issue in biology. The necessary empirical studies comparing the outcomes of alternative reproductive modes on life history traits are rare and focus mainly on traits directly associated with reproductive fitness. Immune function determines the ability of individuals to defend themselves against injury and disease and is therefore likely to have a significant impact on fitness. Here, we used the facultatively parthenogenetic Australian phasmatid, Extatosoma tiaratum, to investigate the effect of both maternal and offspring mode of conception (sexual or parthenogenetic) on offspring immune function (haemocyte concentration, lytic activity and phenoloxidase activity). We show that when parthenogenesis persists beyond one generation, it has negative effects on immune response in terms of haemocyte concentration and lytic activity. Phenoloxidase activity positively correlates with the level of microsatellite heterozygosity. Moreover, immune response decreases across consecutive sampling weeks, suggesting there are physiological constraints with respect to mounting immune responses in close time intervals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Establishment of autologous embryonic stem cells derived from preantral follicle culture and oocyte parthenogenesis.

    PubMed

    Lee, Seung Tae; Choi, Mun Hwan; Lee, Eun Ju; Gong, Seung Pyo; Jang, Mi; Park, Sang Hyun; Jee, Hyang; Kim, Dae Yong; Han, Jae Yong; Lim, Jeong Mook

    2008-11-01

    To evaluate whether autologous embryonic stem cells can be established without generating clone embryos. Prospective model study. Gamete and stem cell biotechnology laboratory in Seoul National University, Seoul, Korea. F1 hybrid B6D2F1 mice. Preantral follicles were cultured, and oocytes matured in the follicles were parthenogenetically activated. Preimplantation development and stem cell characterization. More intrafollicular oocytes that were retrieved from secondary follicles matured and developed into blastocysts after parthenogenesis than those that were retrieved from primary follicles. Of those 35 blastocysts derived from 193 parthenotes, one line of colony-forming cells was established from the culturing of early secondary follicles. The established cells were positive for embryonic stem cell-specific markers and had normal diploid karyotype and telomerase activity. They differentiated into embryoid bodies in vitro and teratomas in vivo. Inducible differentiation of the established cells into neuronal lineage cells also was possible. Autologous embryonic stem cells can be established by preantral follicle culture and oocyte parthenogenesis. A combined technique of follicle culture and oocyte parthenogenesis that does not use developmentally competent oocytes has the potential to replace somatic cell nuclear transfer for autologous cell therapy.

  19. Geographical Distribution of Federal Science Funds to Colleges and Universities. Report of the Comptroller General of the United States.

    ERIC Educational Resources Information Center

    Comptroller General of the U.S., Washington, DC.

    This report provides data on the geographical distribution patterns of federal research and development and other funds to colleges and universities, information on federal programs established in the 1960's to strengthen academic science, and factors accounting for progress by universities in competing for federal funds. Summarizing statements…

  20. Thelytokous parthenogenesis by queens in the dacetine ant Pyramica membranifera (Hymenoptera: Formicidae).

    PubMed

    Ito, Fuminori; Touyama, Yoshifumi; Gotoh, Ayako; Kitahiro, Shungo; Billen, Johan

    2010-08-01

    Thelytokous parthenogenesis in which diploid females are produced from unfertilized eggs, was recently reported for some ant species. Here, we document thelytokous reproduction by queens in the polygynous species Pyramica membranifera. Queens that emerged in the laboratory were kept with or without workers under laboratory conditions. Independent colony founding was successful for a few queens if prey was provided. All artificial colonies, which started with a newly emerged queen and workers produced new workers and some of the colonies also produced female sexuals. Some of the female sexuals shed their wings in the laboratory and started formation of new polygynous colonies. Workers had no ovaries and thus, were obligatorily sterile.

  1. Thelytokous parthenogenesis by queens in the dacetine ant Pyramica membranifera (Hymenoptera: Formicidae)

    NASA Astrophysics Data System (ADS)

    Ito, Fuminori; Touyama, Yoshifumi; Gotoh, Ayako; Kitahiro, Shungo; Billen, Johan

    2010-08-01

    Thelytokous parthenogenesis in which diploid females are produced from unfertilized eggs, was recently reported for some ant species. Here, we document thelytokous reproduction by queens in the polygynous species Pyramica membranifera. Queens that emerged in the laboratory were kept with or without workers under laboratory conditions. Independent colony founding was successful for a few queens if prey was provided. All artificial colonies, which started with a newly emerged queen and workers produced new workers and some of the colonies also produced female sexuals. Some of the female sexuals shed their wings in the laboratory and started formation of new polygynous colonies. Workers had no ovaries and thus, were obligatorily sterile.

  2. Cyclical parthenogenesis algorithm for layout optimization of truss structures with frequency constraints

    NASA Astrophysics Data System (ADS)

    Kaveh, A.; Zolghadr, A.

    2017-08-01

    Structural optimization with frequency constraints is seen as a challenging problem because it is associated with highly nonlinear, discontinuous and non-convex search spaces consisting of several local optima. Therefore, competent optimization algorithms are essential for addressing these problems. In this article, a newly developed metaheuristic method called the cyclical parthenogenesis algorithm (CPA) is used for layout optimization of truss structures subjected to frequency constraints. CPA is a nature-inspired, population-based metaheuristic algorithm, which imitates the reproductive and social behaviour of some animal species such as aphids, which alternate between sexual and asexual reproduction. The efficiency of the CPA is validated using four numerical examples.

  3. DNA evidence for nonhybrid origins of parthenogenesis in natural populations of vertebrates.

    PubMed

    Sinclair, Elizabeth A; Pramuk, Jennifer B; Bezy, Robert L; Crandall, Keith A; Sites, Jack W

    2010-05-01

    Naturally occurring unisexual reproduction has been documented in less than 0.1% of all vertebrate species. Among vertebrates, true parthenogenesis is known only in squamate reptiles. In all vertebrate cases that have been carefully studied, the clonal or hemiclonal taxa have originated through hybridization between closely related sexual species. In contrast, parthenogenetic reproduction has arisen in invertebrates by a variety of mechanisms, including likely cases of "spontaneous" (nonhybrid) origin, a situation not currently documented in natural populations of vertebrates. Here, we present molecular data from the Neotropical night lizard genus Lepidophyma that provides evidence of independent nonhybrid origins for diploid unisexual populations of two species from Costa Rica and Panama. Our mitochondrial and nuclear phylogenies are congruent with respect to the unisexual taxa. Based on 14 microsatellite loci, heterozygosity (expected from a hybrid origin) is low in Lepidophyma reticulatum and completely absent in unisexual L. flavimaculatum. The unique value of this system will allow direct comparative studies between parthenogenetic and sexual lineages in vertebrates, with an enormous potential for this species to be a model system for understanding the mechanisms of nonhybrid parthenogenesis.

  4. Meiotic Parthenogenesis in a Root-Knot Nematode Results in Rapid Genomic Homozygosity

    PubMed Central

    Liu, Qingli L.; Thomas, Varghese P.; Williamson, Valerie M.

    2007-01-01

    Many isolates of the plant-parasitic nematode Meloidogyne hapla reproduce by facultative meiotic parthenogenesis. Sexual crosses can occur, but, in the absence of males, the diploid state appears to be restored by reuniting sister chromosomes of a single meiosis. We have crossed inbred strains of M. hapla that differ in DNA markers and produced hybrids and F2 lines. Here we show that heterozygous M. hapla females, upon parthenogenetic reproduction, produce progeny that segregate 1:1 for the presence or absence of dominant DNA markers, as would be expected if sister chromosomes are rejoined, rather than the 3:1 ratio typical of a Mendelian cross. Codominant markers also segregate 1:1 and heterozygotes are present at low frequency (<3%). Segregation patterns and recombinant analysis indicate that a homozygous condition is prevalent for markers flanking recombination events, suggesting that recombination occurs preferentially as four-strand exchanges at similar locations between both pairs of non-sister chromatids. With this mechanism, meiotic parthenogenesis would be expected to result in rapid genomic homozygosity. This type of high negative crossover interference coupled with positive chromatid interference has not been observed in fungal or other animal systems in which it is possible to examine the sister products of a single meiosis and may indicate that meiotic recombination in this nematode has novel features. PMID:17483427

  5. A successful crayfish invader is capable of facultative parthenogenesis: a novel reproductive mode in decapod crustaceans.

    PubMed

    Buřič, Miloš; Hulák, Martin; Kouba, Antonín; Petrusek, Adam; Kozák, Pavel

    2011-01-01

    Biological invasions are impacting biota worldwide, and explaining why some taxa tend to become invasive is of major scientific interest. North American crayfish species, particularly of the family Cambaridae, are prominent invaders in freshwaters, defying the "tens rule" which states that only a minority of species introduced to new regions become established, and only a minority of those become invasive and pests. So far, success of cambarid invaders has largely been attributed to rapid maturation, high reproductive output, aggressiveness, and tolerance to pollution. We provide experimental evidence that females of one cambarid species particularly widespread in Europe, the spiny-cheek crayfish Orconectes limosus, are capable of facultative parthenogenesis. Such reproductive mode has never before been recognized in decapods, the most diverse crustacean order. As shown by analysis of seven microsatellite loci, crayfish females kept physically separated from males produced genetically homogeneous offspring identical with maternal individuals; this suggests they reproduced by apomixis, unlike those females which mated with males and had a diverse offspring. Further research is needed to clarify what environmental conditions are necessary for a switch to parthenogenesis in O. limosus, and what role it plays in natural crayfish populations. However, if such reproductive plasticity is present in other cambarid crayfish species, it may contribute to the overwhelming invasive success of this group.

  6. A new cytogenetic mechanism for bacterial endosymbiont-induced parthenogenesis in Hymenoptera

    PubMed Central

    Adachi-Hagimori, Tetsuya; Miura, Kazuki; Stouthamer, Richard

    2008-01-01

    Vertically transmitted endosymbiotic bacteria, such as Wolbachia, Cardinium and Rickettsia, modify host reproduction in several ways to facilitate their own spread. One such modification results in parthenogenesis induction, where males, which are unable to transmit the bacteria, are not produced. In Hymenoptera, the mechanism of diploidization due to Wolbachia infection, known as gamete duplication, is a post-meiotic modification. During gamete duplication, the meiotic mechanism is normal, but in the first mitosis the anaphase is aborted. The two haploid sets of chromosomes do not separate and thus result in a single nucleus containing two identical sets of haploid chromosomes. Here, we outline an alternative cytogenetic mechanism for bacterial endosymbiont-induced parthenogenesis in Hymenoptera. During female gamete formation in Rickettsia-infected Neochrysocharis formosa (Westwood) parasitoids, meiotic cells undergo only a single equational division followed by the expulsion of a single polar body. This absence of meiotic recombination and reduction corresponds well with a non-segregation pattern in the offspring of heterozygous females. We conclude that diploidy in N. formosa is maintained through a functionally apomictic cloning mechanism that differs entirely from the mechanism induced by Wolbachia. PMID:18713719

  7. Reproductive plasticity in freshwater invader: from long-term sperm storage to parthenogenesis.

    PubMed

    Buřič, Miloš; Kouba, Antonín; Kozák, Pavel

    2013-01-01

    Orconectes limosus, a North American crayfish species, is one of the most important aquatic invaders in European inland waters. Despite more than 120 years occurrence in Europe and intense research, there are still gaps in knowledge of its life history and ecology. Investigation into O. limosus invasive success requires identifying the mechanisms that enabled them to establish dense and widespread populations from small initial numbers without observable limitation by an introduction bottleneck. In part, O. limosus success may lie in its ability to reproduce by facultative parthenogenesis. Moreover, there are possible other mating scenarios, because of two mating seasons (autumn and spring) in O. limosus. This work investigated the effect of four reproductive scenarios (autumn mating only, spring mating only, autumn and spring mating, and without mating) on the reproductive success of O. limosus. Females successfully reproduced in all tested mating regimes using parthenogenesis as well as log term sperm storage. This reproductive plasticity likely facilitates the overwhelming success of O. limosus spread and establishment in new localities. It can explain the spread of O. limosus from the initial introduction of 90 specimens to most of continental Europe and Great Britain. These conclusions imply a serious threat, not only for autochthonous European astacofauna, but for other aquatic organisms as well as entire ecosystems.

  8. A Successful Crayfish Invader Is Capable of Facultative Parthenogenesis: A Novel Reproductive Mode in Decapod Crustaceans

    PubMed Central

    Buřič, Miloš; Hulák, Martin; Kouba, Antonín

    2011-01-01

    Biological invasions are impacting biota worldwide, and explaining why some taxa tend to become invasive is of major scientific interest. North American crayfish species, particularly of the family Cambaridae, are prominent invaders in freshwaters, defying the “tens rule” which states that only a minority of species introduced to new regions become established, and only a minority of those become invasive and pests. So far, success of cambarid invaders has largely been attributed to rapid maturation, high reproductive output, aggressiveness, and tolerance to pollution. We provide experimental evidence that females of one cambarid species particularly widespread in Europe, the spiny-cheek crayfish Orconectes limosus, are capable of facultative parthenogenesis. Such reproductive mode has never before been recognized in decapods, the most diverse crustacean order. As shown by analysis of seven microsatellite loci, crayfish females kept physically separated from males produced genetically homogeneous offspring identical with maternal individuals; this suggests they reproduced by apomixis, unlike those females which mated with males and had a diverse offspring. Further research is needed to clarify what environmental conditions are necessary for a switch to parthenogenesis in O. limosus, and what role it plays in natural crayfish populations. However, if such reproductive plasticity is present in other cambarid crayfish species, it may contribute to the overwhelming invasive success of this group. PMID:21655282

  9. Reproductive Plasticity in Freshwater Invader: From Long-Term Sperm Storage to Parthenogenesis

    PubMed Central

    Buřič, Miloš; Kouba, Antonín; Kozák, Pavel

    2013-01-01

    Orconectes limosus, a North American crayfish species, is one of the most important aquatic invaders in European inland waters. Despite more than 120 years occurrence in Europe and intense research, there are still gaps in knowledge of its life history and ecology. Investigation into O. limosus invasive success requires identifying the mechanisms that enabled them to establish dense and widespread populations from small initial numbers without observable limitation by an introduction bottleneck. In part, O. limosus success may lie in its ability to reproduce by facultative parthenogenesis. Moreover, there are possible other mating scenarios, because of two mating seasons (autumn and spring) in O. limosus. This work investigated the effect of four reproductive scenarios (autumn mating only, spring mating only, autumn and spring mating, and without mating) on the reproductive success of O. limosus. Females successfully reproduced in all tested mating regimes using parthenogenesis as well as log term sperm storage. This reproductive plasticity likely facilitates the overwhelming success of O. limosus spread and establishment in new localities. It can explain the spread of O. limosus from the initial introduction of 90 specimens to most of continental Europe and Great Britain. These conclusions imply a serious threat, not only for autochthonous European astacofauna, but for other aquatic organisms as well as entire ecosystems. PMID:24204886

  10. Parental sex effect of parthenogenesis on hatchability and sperm-egg penetration in mated Chinese Painted quail (Coturnix chinensis).

    PubMed

    Parker, H M; Ramachandran, R; Nascimento Dos Santos, M; Kawaoku, A J; Wade, C R; Lott, K D; McDaniel, C D

    2017-04-01

    Selecting quail for an increased incidence of parthenogenesis also impacts egg weight and albumen pH as well as reduces hatchability and fertility due to decreased sperm-egg penetration (SEP). However, it is unknown which parental sex is responsible for these changes in quail selected for parthenogenesis. Therefore, the objective of this study was to determine which sex influences egg weight, albumen pH, hatchability, and SEP in birds selected for parthenogenesis. In this study, 2 lines of birds were used: 1 line that was selected for parthenogenesis and 1 line not selected for parthenogenesis (control). Treatments were as follows: control females w/control males, control females w/parthenogenetic line males, parthenogenetic line females w/control males, and parthenogenetic line females w/parthenogenetic line males. Fresh eggs were collected daily, labeled and analyzed for albumen pH and SEP or incubated at 37.5 °C for 20 d of incubation. Eggs were candled at 10 days of incubation (DOI) and eggs exhibiting little or no embryonic development were removed and broken open to determine hatching failure. This was repeated at 20 DOI for eggs that did not hatch. A dam main effect for egg set weight existed with parthenogenetic line dams exhibiting heavier eggs than control dams. The parthenogenetic line dams and sires exhibited lower albumen pH and hatch but a higher incidence of parthenogenesis than control line dams or sires. However, only a sire main effect existed for fertility and SEP. Sires from the parthenogenetic line yielded the highest infertility due to lower SEP. In conclusion, both the parthenogenetic line dams and sires contribute to reduced reproductive performance. However, it appears that the sire from the parthenogenetic line is responsible for lower fertility due to a reduction in SEP. Because the sire has a negative impact on overall fertility, it is possible that males selected for parthenogenesis have poorer semen quality resulting in fewer sperm

  11. Nuclear reprogramming: the strategy used in normal development is also used in somatic cell nuclear transfer and parthenogenesis.

    PubMed

    Gao, Tianlong; Zheng, Junke; Xing, Fengying; Fang, Haiyan; Sun, Feng; Yan, Ayong; Gong, Xun; Ding, Hui; Tang, Fan; Sheng, Hui Z

    2007-02-01

    Somatic cell nuclear transfer (SCNT) and parthenogenesis are alternative forms of reproduction and development, building new life cycles on differentiated somatic cell nuclei and duplicated maternal chromatin, respectively. In the preceding paper (Sun F, et al., Cell Res 2007; 17:117-134.), we showed that an "erase-and-rebuild" strategy is used in normal development to transform the maternal gene expression profile to a zygotic one. Here, we investigate if the same strategy also applies to SCNT and parthenogenesis. The relationship between chromatin and chromatin factors (CFs) during SCNT and parthenogenesis was examined using immunochemical and GFP-fusion protein assays. Results from these studies indicated that soon after nuclear transfer, a majority of CFs dissociated from somatic nuclei and were redistributed to the cytoplasm of the egg. The erasure process in oogenesis is recaptured during the initial phase in SCNT. Most CFs entered pseudo-pronuclei shortly after their formation. In parthenogenesis, all parthenogenotes underwent normal oogenesis, and thus had removed most CFs from chromosomes before the initiation of development. The CFs were subsequently re-associated with female pronuclei in time and sequence similar to that in fertilized embryos. Based on these data, we conclude that the "erase-and-rebuild" process observed in normal development also occurs in SCNT and in parthenogenesis, albeit in altered fashions. The process is responsible for transcription reprogramming in these procedures. The "erase" process in SCNT is compressed and the efficiency is compromised, which likely contribute to the developmental defects often observed in nuclear transfer (nt) embryos. Furthermore, results from this study indicated that the cytoplasm of an egg contains most, if not all, essential components for assembling the zygotic program and can assemble them onto appropriate diploid chromatin of distinct origins.

  12. Parthenogenesis in unfertilized eggs of Coturnix chinensis, the Chinese painted quail, and the effect of egg clutch position on embryonic development.

    PubMed

    Parker, H M; McDaniel, C D

    2009-04-01

    Parthenogenesis, embryonic development of an unfertilized egg, was studied for many years in turkeys. In fact, as many as 49% of unfertilized Beltsville Small White turkey eggs develop embryos. However, no research exists on parthenogenesis in quail. The Chinese painted quail is a close relative of the more common Japanese quail and, unlike turkeys or chickens, the small Chinese painted quail reaches sexual maturity rapidly, making it a great candidate for further research on parthenogenesis. Obviously, a better understanding of avian parthenogenesis should increase our knowledge of avian fertilization and early embryonic development. Therefore, we determined if unfertilized Chinese painted quail hens produce embryos. Second, we explored the possibility that position of the egg within the clutch influences parthenogenesis. When initial secondary sexual plumage was apparent at 4 wk of age, male chicks were separated from females to prevent fertilization. Hens were placed in individual cages near sexual maturity, at approximately 6 wk of age. Individual eggs were collected daily and labeled with hen number and date. Eggs were stored for 0 to 3 d at 20 degrees C before incubation at 37.5 degrees C. After 10 d of incubation, approximately 4,000 eggs from 300 laying hens were examined for embryonic development under a magnifying lamp. On average, 4.8% of the unfertilized eggs contained an abortive form of embryonic development consisting of undifferentiated cells and unorganized membranes. Approximately 27% of the laying hens produced at least 1 egg with parthenogenic development. However, about 10% (30) of these hens exhibited a predisposition for parthenogenesis by producing 2 or more unfertilized eggs with embryonic development. Twenty percent of the eggs from 2 hens produced embryonic development. Additionally, the first egg laid in a clutch was most likely to produce embryonic development, with a steady decline in the percentage of eggs with embryonic development

  13. Induced parthenogenesis by gamma-irradiated pollen in loquat for haploid production.

    PubMed

    Blasco, Manuel; Badenes, María Luisa; Del Mar Naval, María

    2016-09-01

    Successful haploid induction in loquat ( Eriobotrya japonica (Thunb.) Lindl.) through in situ-induced parthenogenesis with gamma-ray irradiated pollen has been achieved. Female flowers of cultivar 'Algerie' were pollinated using pollen of cultivars 'Changhong-3', 'Cox' and 'Saval Brasil' irradiated with two doses of gamma rays, 150 and 300 Gy. The fruits were harvested 90, 105 and 120 days after pollination (dap). Four haploid plants were obtained from 'Algerie' pollinated with 300-Gy-treated pollen of 'Saval Brasil' from fruits harvested 105 dap. Haploidy was confirmed by flow cytometry and chromosome count. The haploids showed a very weak development compared to the diploid plants. This result suggests that irradiated pollen can be used to obtain parthenogenetic haploids.

  14. Induced parthenogenesis by gamma-irradiated pollen in loquat for haploid production

    PubMed Central

    Blasco, Manuel; Badenes, María Luisa; del Mar Naval, María

    2016-01-01

    Successful haploid induction in loquat (Eriobotrya japonica (Thunb.) Lindl.) through in situ-induced parthenogenesis with gamma-ray irradiated pollen has been achieved. Female flowers of cultivar ‘Algerie’ were pollinated using pollen of cultivars ‘Changhong-3’, ‘Cox’ and ‘Saval Brasil’ irradiated with two doses of gamma rays, 150 and 300 Gy. The fruits were harvested 90, 105 and 120 days after pollination (dap). Four haploid plants were obtained from ‘Algerie’ pollinated with 300-Gy-treated pollen of ‘Saval Brasil’ from fruits harvested 105 dap. Haploidy was confirmed by flow cytometry and chromosome count. The haploids showed a very weak development compared to the diploid plants. This result suggests that irradiated pollen can be used to obtain parthenogenetic haploids. PMID:27795686

  15. Tissue engineering, stem cells, cloning, and parthenogenesis: new paradigms for therapy.

    PubMed

    Hipp, Jason; Atala, Anthony

    2004-12-08

    : BACKGROUND: Patients suffering from diseased and injured organs may be treated with transplanted organs. However, there is a severe shortage of donor organs which is worsening yearly due to the aging population. Scientists in the field of tissue engineering apply the principles of cell transplantation, materials science, and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. Both therapeutic cloning (nucleus from a donor cell is transferred into an enucleated oocyte), and parthenogenesis (oocyte is activated and stimulated to divide), permit extraction of pluripotent embryonic stem cells, and offer a potentially limitless source of cells for tissue engineering applications. The stem cell field is also advancing rapidly, opening new options for therapy. The present article reviews recent progress in tissue engineering and describes applications of these new technologies that may offer novel therapies for patients with end-stage organ failure.

  16. Tissue engineering, stem cells, cloning, and parthenogenesis: new paradigms for therapy

    PubMed Central

    Hipp, Jason; Atala, Anthony

    2004-01-01

    Patients suffering from diseased and injured organs may be treated with transplanted organs. However, there is a severe shortage of donor organs which is worsening yearly due to the aging population. Scientists in the field of tissue engineering apply the principles of cell transplantation, materials science, and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. Both therapeutic cloning (nucleus from a donor cell is transferred into an enucleated oocyte), and parthenogenesis (oocyte is activated and stimulated to divide), permit extraction of pluripotent embryonic stem cells, and offer a potentially limitless source of cells for tissue engineering applications. The stem cell field is also advancing rapidly, opening new options for therapy. The present article reviews recent progress in tissue engineering and describes applications of these new technologies that may offer novel therapies for patients with end-stage organ failure. PMID:15588286

  17. Meiosis, unreduced gametes, and parthenogenesis: implications for engineering clonal seed formation in crops.

    PubMed

    Ronceret, Arnaud; Vielle-Calzada, Jean-Philippe

    2015-06-01

    Meiosis and unreduced gametes. Sexual flowering plants produce meiotically derived cells that give rise to the male and female haploid gametophytic phase. In the ovule, usually a single precursor (the megaspore mother cell) undergoes meiosis to form four haploid megaspores; however, numerous mutants result in the formation of unreduced gametes, sometimes showing female specificity, a phenomenon reminiscent of the initiation of gametophytic apomixis. Here, we review the developmental events that occur during female meiosis and megasporogenesis at the light of current possibilities to engineer unreduced gamete formation. We also provide an overview of the current understanding of mechanisms leading to parthenogenesis and discuss some of the conceptual implications for attempting the induction of clonal seed production in cultivated plants.

  18. Apomictic parthenogenesis in a parasitoid wasp Meteorus pulchricornis, uncommon in the haplodiploid order Hymenoptera.

    PubMed

    Tsutsui, Y; Maeto, K; Hamaguchi, K; Isaki, Y; Takami, Y; Naito, T; Miura, K

    2014-06-01

    Although apomixis is the most common form of parthenogenesis in diplodiploid arthropods, it is uncommon in the haplodiploid insect order Hymenoptera. We found a new type of spontaneous apomixis in the Hymenoptera, completely lacking meiosis and the expulsion of polar bodies in egg maturation division, on the thelytokous strain of a parasitoid wasp Meteorus pulchricornis (Wesmael) (Braconidae, Euphorinae) on pest lepidopteran larvae Spodoptera litura (Fabricius) (Noctuidae). The absence of the meiotic process was consistent with a non-segregation pattern in the offspring of heterozygous females, and no positive evidence was obtained for the induction of thelytoky by any bacterial symbionts. We discuss the conditions that enable the occurrence of such rare cases of apomictic thelytoky in the Hymenoptera, suggesting the significance of fixed heterosis caused by hybridization or polyploidization, symbiosis with bacterial agents, and occasional sex. Our finding will encourage further genetic studies on parasitoid wasps to use asexual lines more wisely for biological control.

  19. Socioeconomic and geographical variation in general practitioner consultations for allergic rhinitis in England, 2003–2014: an observational study

    PubMed Central

    Todkill, Daniel; Loveridge, Paul; Elliot, Alex James; Morbey, Roger; de Lusignan, Simon; Edeghere, Obaghe; Smith, Gillian

    2017-01-01

    Objective Allergic rhinitis (AR) is a global health problem, potentially impacting individuals’ sleep, work and social life. We aimed to use a surveillance network of general practitioners (GPs) to describe the epidemiology of AR consultations in England. Setting A large GP surveillance network covering approximately 53% of the English population. Methods GP consultations for AR across England between 30 December 2002 and 31 December 2014 were analysed. Using more granular data available between 2 April 2012 and 31 December 2014 rates and rate ratios (RR) of AR were further analysed in different age groups, gender, rural-urban classification and index of multiple deprivation score quintile of location of GP. Results The mean weekly rate for AR consultations was 19.8 consultations per 100 000 GP registered patients (range 1.13–207), with a regular peak occurring during June (weeks 24–26), and a smaller peak during April. Between 1 April 2012 and 31 December 2014, the highest mean daily rates of consultations per 1 00 000 were: in age group 5–14 years (rate=8.02, RR 6.65, 95% CI 6.38 to 6.93); females (rate=4.57, RR 1.12 95% CI 1.12 to 1.13); persons registered at a GP in the most socioeconomically deprived quintile local authority (rate=5.69, RR 1.48, 95% CI 1.47 to 1.49) or in an urban area with major conurbation (rate=5.91, RR 1.78, 95% CI 1.69 to 1.87). Conclusions AR rates were higher in those aged 5–14 years, females and in urban and socioeconomically deprived areas. This needs to be viewed in the context of this study’s limitations but should be considered in health promotion and service planning. PMID:28801431

  20. First record of second-generation facultative parthenogenesis in a vertebrate species, the whitespotted bambooshark Chiloscyllium plagiosum.

    PubMed

    Straube, N; Lampert, K P; Geiger, M F; Weiß, J D; Kirchhauser, J X

    2016-02-01

    In this study, two parthenogenetic events within a family of the whitespotted bambooshark Chiloscyllium plagiosum are reported. A captive female produced multiple parthenogens. Unexpectedly, a single specimen of a total of nine parthenogens displayed external claspers characterizing the male sex in chondrichthyans. Upon dissection, internal sexual organs of this specimen were malformed or absent; however, the presence of claspers in this study challenges the as yet assumed sex determination system in this shark species. Even more remarkable was that one of the female parthenogens reproduced asexually again producing viable offspring. As far as is known, this is the first genetically confirmed evidence for second-generation facultative parthenogenesis in vertebrates. These results support the evolutionary significance of parthenogenesis as an alternative to sexual reproduction. © 2016 The Fisheries Society of the British Isles.

  1. Genome-wide gene expression profiling reveals aberrant MAPK and Wnt signaling pathways associated with early parthenogenesis.

    PubMed

    Liu, Na; Enkemann, Steven A; Liang, Ping; Hersmus, Remko; Zanazzi, Claudia; Huang, Junjiu; Wu, Chao; Chen, Zhisheng; Looijenga, Leendert H J; Keefe, David L; Liu, Lin

    2010-12-01

    Mammalian parthenogenesis could not survive but aborted during mid-gestation, presumably because of lack of paternal gene expression. To understand the molecular mechanisms underlying the failure of parthenogenesis at early stages of development, we performed global gene expression profiling and functional analysis of parthenogenetic blastocysts in comparison with those of blastocysts from normally fertilized embryos. Parthenogenetic blastocysts exhibited changes in the expression of 749 genes, of which 214 had lower expression and 535 showed higher expressions than fertilized embryos using a minimal 1.8-fold change as a cutoff. Genes important for placenta development were decreased in their expression in parthenote blastocysts. Some maternally expressed genes were up-regulated and paternal-related genes were down-regulated. Moreover, aberrantly increased Wnt signaling and reduced mitogen-activated protein kinase (MAPK) signaling were associated with early parthenogenesis. The protein level of extracellular signal-regulated kinase 2 (ERK2) was low in parthenogenetic blastocysts compared with that of fertilized blastocysts 120 h after fertilization. 6-Bromoindirubin-3'-oxime, a specific glycogen synthase kinase-3 (GSK-3) inhibitor, significantly decreased embryo hatching. The expression of several imprinted genes was altered in parthenote blastocysts. Gene expression also linked reduced expression of Xist to activation of X chromosome. Our findings suggest that failed X inactivation, aberrant imprinting, decreased ERK/MAPK signaling and possibly elevated Wnt signaling, and reduced expression of genes for placental development collectively may contribute to abnormal placenta formation and failed fetal development in parthenogenetic embryos.

  2. Parthenogenesis in non-rodent species: developmental competence and differentiation plasticity.

    PubMed

    Brevini, T A L; Pennarossa, G; Vanelli, A; Maffei, S; Gandolfi, F

    2012-03-01

    An oocyte can activate its developmental process without the intervention of the male counterpart. This form of reproduction, known as parthenogenesis, occurs spontaneously in a variety of lower organisms, but not in mammals. However, it must be noted that mammalian oocytes can be activated in vitro, mimicking the intracellular calcium wave induced by the spermatozoon at fertilization, which triggers cleavage divisions and embryonic development. The resultant parthenotes are not capable of developing to term and arrest their growth at different stages, depending on the species. It is believed that this arrest is due to genomic imprinting, which causes the repression of genes normally expressed by the paternal allele. Human parthenogenetic embryos have recently been proposed as an alternative, less controversial source of embryonic stem cell lines, based on their inherent inability to form a new individual. However many aspects related to the biology of parthenogenetic embryos and parthenogenetically derived cell lines still need to be elucidated. Limited information is available in particular on the consequences of the lack of centrioles and on the parthenote's ability to assemble a new embryonic centrosome in the absence of the sperm centriole. Indeed, in lower species, successful parthenogenesis largely depends upon the oocyte's ability to regenerate complete and functional centrosomes in the absence of the material supplied by a male gamete, while the control of this event appears to be less stringent in mammalian cells. In an attempt to better elucidate some of these aspects, parthenogenetic cell lines, recently derived in our laboratory, have been characterized for their pluripotency. In vitro and in vivo differentiation plasticity have been assessed, demonstrating the ability of these cells to differentiate into cell types derived from the three germ layers. These results confirmed common features between uni- and bi-parental embryonic stem cells. However

  3. Geographical Theories.

    ERIC Educational Resources Information Center

    Golledge, Reginald G.

    1996-01-01

    Discusses the origin of theories in geography and particularly the development of location theories. Considers the influence of economic theory on agricultural land use, industrial location, and geographic location theories. Explores a set of interrelated activities that show how the marketing process illustrates process theory. (MJP)

  4. Phenotypic effects of an allele causing obligate parthenogenesis in a rotifer.

    PubMed

    Scheuerl, Thomas; Riss, Simone; Stelzer, Claus-Peter

    2011-01-01

    Transitions to obligate asexuality have been documented in almost all metazoan taxa, yet the conditions favoring such transitions remained largely unexplored. We address this problem in the rotifer Brachionus calyciflorus. In this species, a polymorphism at a single locus, op, can result in transitions to obligate parthenogenesis. Homozygotes for the op allele reproduce strictly by asexual reproduction, whereas heterozygous clones (+/op) and wild-type clones (+/+) are cyclical parthenogens that undergo sexual reproduction at high population densities. Here, we examine dosage effects of the op allele by analyzing various life-history characteristics and population traits in 10 clones for each of the 3 possible genotypes (op/op, +/op, and +/+). For most traits, we found that op/op clones differed significantly (P < 0.05) from the 2 cyclical parthenogenetic genotypes (+/+ and +/op). By contrast, the 2 cyclical parthenogenetic genotypes were almost indistinguishable, except that heterozygote individuals were slightly but significantly smaller in body size compared with wild-type individuals. Overall, this indicates that the op allele is selectively neutral in the heterozygous state. Thus, selective sweeps of this allele in natural populations would first require conditions favoring the generation of homozygotes. This may be given by inbreeding in very small populations or by double mutants in very large populations.

  5. Parthenogenesis-derived Multipotent Stem Cells Adapted for Tissue Engineering Applications

    PubMed Central

    Koh, Chester J.; Delo, Dawn M.; Lee, Jang Won; Siddiqui, M. Minhaj; Lanza, Robert P.; Soker, Shay; Yoo, James J.; Atala, Anthony

    2009-01-01

    Embryonic stem cells are envisioned as a viable source of pluripotent cells for use in regenerative medicine applications when donor tissue is not available. However, most current harvest techniques for embryonic stem cells require the destruction of embryos, which has led to significant political and ethical limitations on their usage. Parthenogenesis, the process by which an egg can develop into an embryo in the absence of sperm, may be a potential source of embryonic stem cells that may avoid some of the political and ethical concerns surrounding embryonic stem cells. Here we provide the technical aspects of embryonic stem cell isolation and expansion from the parthenogenetic activation of oocytes. These cells were characterized for their stem-cell properties. In addition, these cells were induced to differentiate to the myogenic, osteogenic, adipogenic, and endothelial lineages, and were able to form muscle-like and bony-like tissue in vivo. Furthermore, parthenogenetic stem cells were able to integrate into injured muscle tissue. Together, these results demonstrate that parthenogenetic stem cells can be successfully isolated and utilized for various tissue engineering applications. PMID:18799133

  6. Phenotypic Effects of an Allele Causing Obligate Parthenogenesis in a Rotifer

    PubMed Central

    Scheuerl, Thomas; Riss, Simone

    2011-01-01

    Transitions to obligate asexuality have been documented in almost all metazoan taxa, yet the conditions favoring such transitions remained largely unexplored. We address this problem in the rotifer Brachionus calyciflorus. In this species, a polymorphism at a single locus, op, can result in transitions to obligate parthenogenesis. Homozygotes for the op allele reproduce strictly by asexual reproduction, whereas heterozygous clones (+/op) and wild-type clones (+/+) are cyclical parthenogens that undergo sexual reproduction at high population densities. Here, we examine dosage effects of the op allele by analyzing various life-history characteristics and population traits in 10 clones for each of the 3 possible genotypes (op/op, +/op, and +/+). For most traits, we found that op/op clones differed significantly (P < 0.05) from the 2 cyclical parthenogenetic genotypes (+/+ and +/op). By contrast, the 2 cyclical parthenogenetic genotypes were almost indistinguishable, except that heterozygote individuals were slightly but significantly smaller in body size compared with wild-type individuals. Overall, this indicates that the op allele is selectively neutral in the heterozygous state. Thus, selective sweeps of this allele in natural populations would first require conditions favoring the generation of homozygotes. This may be given by inbreeding in very small populations or by double mutants in very large populations. PMID:21576287

  7. Independent life history evolution between generations of bivoltine species: a case study of cyclical parthenogenesis.

    PubMed

    Hood, Glen R; Ott, James R

    2017-04-01

    Successive generations of bi- and multivoltine species encounter differing biotic and abiotic environments intra-annually. The question of whether selection can independently adjust the relationship between body size and components of reproductive effort within successive generations in response to generation-specific environmental variation is applicable to a diversity of taxa. Herein, we develop a conceptual framework that illustrates increasingly independent life history adjustments between successive generations of taxa exhibiting complex life cycles. We apply this framework to the reproductive biology of the gall-forming insect, Belonocnema treatae (Hymenoptera: Cynipidae). This bivoltine species expresses cyclical parthenogenesis in which alternating sexual and asexual generations develop in different seasons and different environments. We tested the hypotheses that ecological divergence between the alternate generations is accompanied by generational differences in body size, egg size, and egg number and by changes in the relationships between body size and these components of reproductive effort. Increased potential reproductive effort of sexual generation B. treatae is attained by increased body size and egg number (with no trade-off between egg number and egg size) and by a significant increase in the slope of the relationship between body size and potential fecundity. These generation-specific relationships, interpreted in the context of the model framework, suggest that within each generation selection has independently molded the relationships relating body size to potential fecundity and potential reproductive effort in B. treatae. The conceptual framework is broadly applicable to comparisons involving the alternating generations of bi- and multivoltine species.

  8. Thelytokous Parthenogenesis in Unmated Queen Honeybees (Apis mellifera capensis): Central Fusion and High Recombination Rates

    PubMed Central

    Oldroyd, Benjamin P.; Allsopp, Michael H.; Gloag, Rosalyn S.; Lim, Julianne; Jordan, Lyndon A.; Beekman, Madeleine

    2008-01-01

    The subspecies of honeybee indigenous to the Cape region of South Africa, Apis mellifera capensis, is unique because a high proportion of unmated workers can lay eggs that develop into females via thelytokous parthenogenesis involving central fusion of meiotic products. This ability allows pseudoclonal lineages of workers to establish, which are presently widespread as reproductive parasites within the honeybee populations of South Africa. Successful long-term propagation of a parthenogen requires the maintenance of heterozygosity at the sex locus, which in honeybees must be heterozygous for the expression of female traits. Thus, in successful lineages of parasitic workers, recombination events are reduced by an order of magnitude relative to meiosis in queens of other honeybee subspecies. Here we show that in unmated A. m. capensis queens treated to induce oviposition, no such reduction in recombination occurs, indicating that thelytoky and reduced recombination are not controlled by the same gene. Our virgin queens were able to lay both arrhenotokous male-producing haploid eggs and thelytokous female-producing diploid eggs at the same time, with evidence that they have some voluntary control over which kind of egg was laid. If so, they are able to influence the kind of second-division meiosis that occurs in their eggs post partum. PMID:18716331

  9. Self-oocyte activation and parthenogenesis: an unusual outcome of a misconducted IVF cycle.

    PubMed

    Socolov, Razvan; Ebner, Thomas; Gorduza, Vlad; Martiniuc, Violeta; Angioni, Stefano; Socolov, Demetra

    2015-07-01

    A rare cause of infertility is the lack of fertilisation with the spontaneous activation of oocytes, leading to parthenogenesis. We present such a case. The patient was a G1P0 38-year-old woman of African ethnicity, who requested an in vitro fertilisation (IVF) with donor sperm. She received a stimulation protocol of 75 IU of FSH/LH from day 3 of the cycle, which she interrupted after 2 d, and restarted with the same dosage for another 3 d from day 7, plus one administration of GnRH antagonist in day 10 of the cycle. With a follicle reaching 19 mm on day 11, estradiol of 325 ng/ml, ovulation was induced with hMG 5000 UI, and oocyte pick-up performed at 30 h. One oocyte was retrieved, and good-quality sperms were added to the insemination procedure. No fecundation occurred at 20 h, with the extruded oocyte separated from the granulosa wall. At 40 h and 64 h the aspect was of three cells, one cell with one nucleus, the others with high granulation and no visible nuclei. This case shows an unusual self-activation oocyte in a poorly managed IVF cycle. The patient will be further evaluated, to decide if a better managed stimulation protocol would prevent recurrence.

  10. Artificial parthenogenesis and control of voltinism to manage transgenic populations in Bombyx mori.

    PubMed

    Grenier, Anne-Marie; Da Rocha, Martine; Jalabert, Audrey; Royer, Corinne; Mauchamp, Bernard; Chavancy, Gérard

    2004-08-01

    In order to improve the management of transformed populations in a routine application of transgenesis technology in Bombyx mori, we modified its mode of reproduction and its voltinism. On one hand, after a stable integration of the gene of interest by transgenesis, it is preferable to maintain this gene in an identical genomic context through successive generations. This can be obtained by artificial parthenogenetic reproduction (ameiotic parthenogenesis) giving isogenic females identical to their transformed mother. On the other hand, it is essential to obtain continuous generations (polyvoltinism) after microinjection, in order to screen positive transgenic insects and study genetics and insertion of the transgene. Thereafter, it is more convenient to store these populations, as diapause eggs before their use in biotechnology application. We obtained such polyvoltine parthenoclones, first by selection for a parthenogenetic character in polyvoltine races, and second, by selection for a polyvoltine character in a parthenogenetic, but diapausing clone of B. mori. As diapause was directly under the control of diapause hormone (DH), we also tested direct injection of DH in female pupae of polyvoltine strains, as well as anti-DH antibody treatment to eliminate diapause in univoltine strains. We discussed the advantages and limitations of these methods and proved the feasibility in obtaining polyvoltine parthenoclones and determining the voltinism in B. mori. These methods would permit us to improve the management of populations used in transgenesis technology.

  11. Transfer of a parthenogenesis-inducing Wolbachia endosymbiont derived from Trichogramma dendrolimi into Trichogramma evanescens.

    PubMed

    Watanabe, Masaya; Kageyama, Daisuke; Miura, Kazuki

    2013-01-01

    Wolbachia, which are maternally transmitted endosymbionts, are considered to have moved horizontally between invertebrate hosts multiple times. However, it is not well understood how easily Wolbachia are transmitted horizontally between different hosts and how frequently horizontally-transmitted Wolbachia become established in their new hosts. We transferred a parthenogenesis-inducing Wolbachia endosymbiont derived from the parasitic wasp Trichogramma dendrolimi to Trichogramma evanescens. Specifically, Wolbachia was cultivated in a mosquito cell line and the Wolbachia-infected cells were microinjected into uninfected T. evanescens. Among 276 pupae inoculated with Wolbachia-infected cells, 65 adults emerged (G0). Diagnostic PCR demonstrated that 25 of 37 G0 females (68%) were Wolbachia-positive. Among isofemale lines established from G0 females, the proportions of infected lines were 80% (20 of 25) in G1 and 100% (18 of 18) in G2. In an isofemale line, infection was stably maintained for more than 10 generations. These results indicate invasion of Wolbachia into the germline of the recipient insect. Quantitative PCR demonstrated that the Wolbachia titer in the recipient host was significantly lower than that in the native host. The absence or very low number, if any, of parthenogenetically-reproducing individuals in the recipient host may be caused by the low Wolbachia titer. The Wolbachia titer in the recipients was lower in G11 than in G5, suggesting a decline in the density. Together with a previous report, our study may imply that Wolbachia in Trichogramma species are highly adapted to their hosts, which hinders robust expression of the Wolbachia phenotype in non-native host species. Copyright © 2012 Elsevier Inc. All rights reserved.

  12. Intragenomic conflict in populations infected by Parthenogenesis Inducing Wolbachia ends with irreversible loss of sexual reproduction

    PubMed Central

    2010-01-01

    Background The maternally inherited, bacterial symbiont, parthenogenesis inducing (PI) Wolbachia, causes females in some haplodiploid insects to produce daughters from both fertilized and unfertilized eggs. The symbionts, with their maternal inheritance, benefit from inducing the production of exclusively daughters, however the optimal sex ratio for the nuclear genome is more male-biased. Here we examine through models how an infection with PI-Wolbachia in a previously uninfected population leads to a genomic conflict between PI-Wolbachia and the nuclear genome. In most natural populations infected with PI-Wolbachia the infection has gone to fixation and sexual reproduction is impossible, specifically because the females have lost their ability to fertilize eggs, even when mated with functional males. Results The PI Wolbachia infection by itself does not interfere with the fertilization process in infected eggs, fertilized infected eggs develop into biparental infected females. Because of the increasingly female-biased sex ratio in the population during a spreading PI-Wolbachia infection, sex allocation alleles in the host that cause the production of more sons are rapidly selected. In haplodiploid species a reduced fertilization rate leads to the production of more sons. Selection for the reduced fertilization rate leads to a spread of these alleles through both the infected and uninfected population, eventually resulting in the population becoming fixed for both the PI-Wolbachia infection and the reduced fertilization rate. Fertilization rate alleles that completely interfere with fertilization ("virginity alleles") will be selected over alleles that still allow for some fertilization. This drives the final resolution of the conflict: the irreversible loss of sexual reproduction and the complete dependence of the host on its symbiont. Conclusions This study shows that dependence among organisms can evolve rapidly due to the resolution of the conflicts between

  13. Facultative use of thelytokous parthenogenesis for queen production in the polyandrous ant Cataglyphis cursor.

    PubMed

    Doums, C; Cronin, A L; Ruel, C; Fédérici, P; Haussy, C; Tirard, C; Monnin, T

    2013-07-01

    The evolutionary paradox of sex remains one of the major debates in evolutionary biology. The study of species capable of both sexual and asexual reproduction can elucidate factors important in the evolution of sex. One such species is the ant Cataglyphis cursor, where the queen maximizes the transmission of her genes by producing new queens (gynes) asexually while simultaneously maintaining a genetically diverse workforce via the sexual production of workers. We show that the queen can also produce gynes sexually and may do so to offset the costs of asexual reproduction. We genotyped 235 gynes from 18 colonies and found that half were sexually produced. A few colonies contained both sexually and asexually produced gynes. Although workers in this species can also use thelytoky, we found no evidence of worker production of gynes based on genotypes of 471 workers from the six colonies producing sexual gynes. Gynes are thus mainly, and potentially exclusively, produced by the queen. Simulations of gynes inbreeding level following one to ten generations of automictic thelytoky suggest that the queen switches between or combines thelytoky and sex, which may reduce the costs of inbreeding. This is supported by the relatively small size of inbred gynes in one colony, although we found no relationship between the level of inbreeding and immune parameters. Such facultative use of sex and thelytoky by individual queens contrasts with other known forms of parthenogenesis in ants, which are typically characterized by distinct lineages specializing in one strategy or the other. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  14. A Parthenogenesis Gene Candidate and Evidence for Segmental Allopolyploidy in Apomictic Brachiaria decumbens

    PubMed Central

    Worthington, Margaret; Heffelfinger, Christopher; Bernal, Diana; Quintero, Constanza; Zapata, Yeny Patricia; Perez, Juan Guillermo; De Vega, Jose; Miles, John; Dellaporta, Stephen; Tohme, Joe

    2016-01-01

    Apomixis, asexual reproduction through seed, enables breeders to identify and faithfully propagate superior heterozygous genotypes by seed without the disadvantages of vegetative propagation or the expense and complexity of hybrid seed production. The availability of new tools such as genotyping by sequencing and bioinformatics pipelines for species lacking reference genomes now makes the construction of dense maps possible in apomictic species, despite complications including polyploidy, multisomic inheritance, self-incompatibility, and high levels of heterozygosity. In this study, we developed saturated linkage maps for the maternal and paternal genomes of an interspecific Brachiaria ruziziensis (R. Germ. and C. M. Evrard) × B. decumbens Stapf. F1 mapping population in order to identify markers linked to apomixis. High-resolution molecular karyotyping and comparative genomics with Setaria italica (L.) P. Beauv provided conclusive evidence for segmental allopolyploidy in B. decumbens, with strong preferential pairing of homologs across the genome and multisomic segregation relatively more common in chromosome 8. The apospory-specific genomic region (ASGR) was mapped to a region of reduced recombination on B. decumbens chromosome 5. The Pennisetum squamulatum (L.) R.Br. PsASGR-BABY BOOM-like (psASGR–BBML)-specific primer pair p779/p780 was in perfect linkage with the ASGR in the F1 mapping population and diagnostic for reproductive mode in a diversity panel of known sexual and apomict Brachiaria (Trin.) Griseb. and P. maximum Jacq. germplasm accessions and cultivars. These findings indicate that ASGR–BBML gene sequences are highly conserved across the Paniceae and add further support for the postulation of the ASGR–BBML as candidate genes for the apomictic function of parthenogenesis. PMID:27206716

  15. A Parthenogenesis Gene Candidate and Evidence for Segmental Allopolyploidy in Apomictic Brachiaria decumbens.

    PubMed

    Worthington, Margaret; Heffelfinger, Christopher; Bernal, Diana; Quintero, Constanza; Zapata, Yeny Patricia; Perez, Juan Guillermo; De Vega, Jose; Miles, John; Dellaporta, Stephen; Tohme, Joe

    2016-07-01

    Apomixis, asexual reproduction through seed, enables breeders to identify and faithfully propagate superior heterozygous genotypes by seed without the disadvantages of vegetative propagation or the expense and complexity of hybrid seed production. The availability of new tools such as genotyping by sequencing and bioinformatics pipelines for species lacking reference genomes now makes the construction of dense maps possible in apomictic species, despite complications including polyploidy, multisomic inheritance, self-incompatibility, and high levels of heterozygosity. In this study, we developed saturated linkage maps for the maternal and paternal genomes of an interspecific Brachiaria ruziziensis (R. Germ. and C. M. Evrard) × B. decumbens Stapf. F1 mapping population in order to identify markers linked to apomixis. High-resolution molecular karyotyping and comparative genomics with Setaria italica (L.) P. Beauv provided conclusive evidence for segmental allopolyploidy in B. decumbens, with strong preferential pairing of homologs across the genome and multisomic segregation relatively more common in chromosome 8. The apospory-specific genomic region (ASGR) was mapped to a region of reduced recombination on B. decumbens chromosome 5. The Pennisetum squamulatum (L.) R.Br. PsASGR-BABY BOOM-like (psASGR-BBML)-specific primer pair p779/p780 was in perfect linkage with the ASGR in the F1 mapping population and diagnostic for reproductive mode in a diversity panel of known sexual and apomict Brachiaria (Trin.) Griseb. and P. maximum Jacq. germplasm accessions and cultivars. These findings indicate that ASGR-BBML gene sequences are highly conserved across the Paniceae and add further support for the postulation of the ASGR-BBML as candidate genes for the apomictic function of parthenogenesis. Copyright © 2016 by the Genetics Society of America.

  16. A methylation status analysis of the apomixis-specific region in Paspalum spp. suggests an epigenetic control of parthenogenesis.

    PubMed

    Podio, Maricel; Cáceres, Maria E; Samoluk, Sergio S; Seijo, José G; Pessino, Silvina C; Ortiz, Juan Pablo A; Pupilli, Fulvio

    2014-12-01

    Apomixis, a clonal plant reproduction by seeds, is controlled in Paspalum spp. by a single locus which is blocked in terms of recombination. Partial sequence analysis of the apomixis locus revealed structural features of heterochromatin, namely the presence of repetitive elements, gene degeneration, and de-regulation. To test the epigenetic control of apomixis, a study on the distribution of cytosine methylation at the apomixis locus and the effect of artificial DNA demethylation on the mode of reproduction was undertaken in two apomictic Paspalum species. The 5-methylcytosine distribution in the apomixis-controlling genomic region was studied in P. simplex by methylation-sensitive restriction fragment length polymorphism (RFLP) analysis and in P. notatum by fluorescene in situ hybridization (FISH). The effect of DNA demethylation was studied on the mode of reproduction of P. simplex by progeny test analysis of apomictic plants treated with the demethylating agent 5'-azacytidine. A high level of cytosine methylation was detected at the apomixis-controlling genomic region in both species. By analysing a total of 374 open pollination progeny, it was found that artificial demethylation had little or no effect on apospory, whereas it induced a significant depression of parthenogenesis. The results suggested that factors controlling repression of parthenogenesis might be inactivated in apomictic Paspalum by DNA methylation. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  17. Thelytokous parthenogenesis, male clonality and genetic caste determination in the little fire ant: new evidence and insights from the lab.

    PubMed

    Foucaud, J; Estoup, A; Loiseau, A; Rey, O; Orivel, J

    2010-08-01

    Previous studies indicate that some populations of the little fire ant, Wasmannia auropunctata, display an unusual reproduction system polymorphism. Although some populations have a classical haplodiploid reproduction system, in other populations queens are produced by thelytokous parthenogenesis, males are produced by a male clonality system and workers are produced sexually. An atypical genetic caste determination system was also suggested. However, these conclusions were indirectly inferred from genetic studies on field population samples. Here we set up experimental laboratory nests that allow the control of the parental relationships between individuals. The queens heading those nests originated from either putatively clonal or sexual populations. We characterized the male, queen and worker offspring they produced at 12 microsatellite loci. Our results unambiguously confirm the unique reproduction system polymorphism mentioned above and that male clonality is strictly associated with thelytokous parthenogenesis. We also observed direct evidence of the rare production of sexual gynes and arrhenotokous males in clonal populations. Finally, we obtained evidence of a genetic basis for caste determination. The evolutionary significance of the reproduction system polymorphism and genetic caste determination as well as future research opportunities are discussed.

  18. 47 CFR 10.450 - Geographic targeting.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Geographic targeting. 10.450 Section 10.450 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMERCIAL MOBILE ALERT SYSTEM Alert Message Requirements § 10.450 Geographic targeting. This section establishes minimum requirements for the geographic...

  19. Sexual conflict over the maintenance of sex: effects of sexually antagonistic coevolution for reproductive isolation of parthenogenesis.

    PubMed

    Kawatsu, Kazutaka

    2013-01-01

    Sexual reproduction involves many costs. Therefore, females acquiring a capacity for parthenogenetic (or asexual) reproduction will gain a reproductive advantage over obligately sexual females. In contrast, for males, any trait coercing parthenogens into sexual reproduction (male coercion) increases their fitness and should be under positive selection because parthenogenesis deprives them of their genetic contribution to future generations. Surprisingly, although such sexual conflict is a possible outcome whenever reproductive isolation is incomplete between parthenogens and the sexual ancestors, it has not been given much attention in the studies of the maintenance of sex. Using two mathematical models, I show here that the evolution of male coercion substantially favours the maintenance of sex even though a female barrier against the coercion can evolve. First, the model based on adaptive-dynamics theory demonstrates that the resultant antagonistic coevolution between male coercion and a female barrier fundamentally ends in either the prevalence of sex or the co-occurrence of two reproductive modes. This is because the coevolution between the two traits additionally involves sex-ratio selection, that is, an increase in parthenogenetic reproduction leads to a female-biased population sex ratio, which will enhance reproductive success of more coercive males and directly promotes the evolution of the coercion among males. Therefore, as shown by the individual-based model, the establishment of obligate parthenogenesis in the population requires the simultaneous evolution of strong reproductive isolation between males and parthenogens. These findings should shed light on the interspecific diversity of reproductive modes as well as help to explain the prevalence of sexual reproduction.

  20. Sexual Conflict over the Maintenance of Sex: Effects of Sexually Antagonistic Coevolution for Reproductive Isolation of Parthenogenesis

    PubMed Central

    Kawatsu, Kazutaka

    2013-01-01

    Sexual reproduction involves many costs. Therefore, females acquiring a capacity for parthenogenetic (or asexual) reproduction will gain a reproductive advantage over obligately sexual females. In contrast, for males, any trait coercing parthenogens into sexual reproduction (male coercion) increases their fitness and should be under positive selection because parthenogenesis deprives them of their genetic contribution to future generations. Surprisingly, although such sexual conflict is a possible outcome whenever reproductive isolation is incomplete between parthenogens and the sexual ancestors, it has not been given much attention in the studies of the maintenance of sex. Using two mathematical models, I show here that the evolution of male coercion substantially favours the maintenance of sex even though a female barrier against the coercion can evolve. First, the model based on adaptive-dynamics theory demonstrates that the resultant antagonistic coevolution between male coercion and a female barrier fundamentally ends in either the prevalence of sex or the co-occurrence of two reproductive modes. This is because the coevolution between the two traits additionally involves sex-ratio selection, that is, an increase in parthenogenetic reproduction leads to a female-biased population sex ratio, which will enhance reproductive success of more coercive males and directly promotes the evolution of the coercion among males. Therefore, as shown by the individual-based model, the establishment of obligate parthenogenesis in the population requires the simultaneous evolution of strong reproductive isolation between males and parthenogens. These findings should shed light on the interspecific diversity of reproductive modes as well as help to explain the prevalence of sexual reproduction. PMID:23469150

  1. Gene expression analysis of parthenogenetic embryonic development of the pea aphid, Acyrthosiphon pisum, suggests that aphid parthenogenesis evolved from meiotic oogenesis.

    PubMed

    Srinivasan, Dayalan G; Abdelhady, Ahmed; Stern, David L

    2014-01-01

    Aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis) during the remainder of the life cycle. The molecular basis for aphid parthenogenesis is unknown. Cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. As a test of these alternatives, we assessed the expression levels and expression patterns of canonical meiotic recombination and germline genes in the sexual and asexual ovaries of the pea aphid, Acyrthosiphon pisum. We observed expression of all meiosis genes in similar patterns in asexual and sexual ovaries, with the exception that some genes encoding Argonaute-family members were not expressed in sexual ovaries. In addition, we observed that asexual aphid tissues accumulated unspliced transcripts of Spo11, whereas sexual aphid tissues accumulated primarily spliced transcripts. In situ hybridization revealed Spo11 transcript in sexual germ cells and undetectable levels of Spo11 transcript in asexual germ cells. We also found that an obligately asexual strain of pea aphid produced little spliced Spo11 transcript. Together, these results suggest that parthenogenetic oogenesis evolved from a meiosis-like, and not a mitosis-like, process and that the aphid reproductive polyphenism may involve a modification of Spo11 gene activity.

  2. Gene Expression Analysis of Parthenogenetic Embryonic Development of the Pea Aphid, Acyrthosiphon pisum, Suggests That Aphid Parthenogenesis Evolved from Meiotic Oogenesis

    PubMed Central

    Srinivasan, Dayalan G.; Abdelhady, Ahmed; Stern, David L.

    2014-01-01

    Aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis) during the remainder of the life cycle. The molecular basis for aphid parthenogenesis is unknown. Cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. As a test of these alternatives, we assessed the expression levels and expression patterns of canonical meiotic recombination and germline genes in the sexual and asexual ovaries of the pea aphid, Acyrthosiphon pisum. We observed expression of all meiosis genes in similar patterns in asexual and sexual ovaries, with the exception that some genes encoding Argonaute-family members were not expressed in sexual ovaries. In addition, we observed that asexual aphid tissues accumulated unspliced transcripts of Spo11, whereas sexual aphid tissues accumulated primarily spliced transcripts. In situ hybridization revealed Spo11 transcript in sexual germ cells and undetectable levels of Spo11 transcript in asexual germ cells. We also found that an obligately asexual strain of pea aphid produced little spliced Spo11 transcript. Together, these results suggest that parthenogenetic oogenesis evolved from a meiosis-like, and not a mitosis-like, process and that the aphid reproductive polyphenism may involve a modification of Spo11 gene activity. PMID:25501006

  3. Thinking Like a Geographer

    ERIC Educational Resources Information Center

    Chernosky, Margaret Shaw

    2012-01-01

    This article presents an activity that engages the student in the geographic inquiry process, the student acquires geographic data and analyzes geographic information to answer a geographic question. The question is: "Do students in my class have place name mastery of the 50 states?" The activity assesses students' geo-literacy and shows the…

  4. Histories of Geographical Education

    ERIC Educational Resources Information Center

    Kent, Ashley

    2006-01-01

    This paper revisits the value of and justification for histories of geographical education as a field of research endeavour within geographical education. Four potentially fruitful areas of research are identified. These are pressure groups, especially the International Geographical Union's Commission on Geographical Education; the influence of…

  5. Where have all the doctors gone? (2). Intraurban trends: changes in the geographic distribution of general practitioners in Auckland, 1980-7.

    PubMed

    Barnett, J R

    1991-08-14

    During the 1980s the Auckland metropolitan area increased its share of all general practitioners in New Zealand at a much faster rate than its share of the population, resulting in a high level of availability by 1987. In the light of such trends, neoclassical theory would predict a diffusion of general practitioners into areas with fewer doctors where there is less competition for patients. Data for 1980-7, however, indicates that for every FTE general practitioner who located in doctor poor areas of the city, 1.87 general practitioners continued to open practices in areas already well provided for. Or, for every extra consultation that took place in low income suburbs, 1.51 extra consultations occurred in more affluent localities. These results do not provide strong support for a market led diffusion of doctors into areas of need and any gains in increased equity appear to have been achieved at the expense of considerable inefficiency given the likely presence of induced demand.

  6. A newly discovered bacterium associated with parthenogenesis and a change in host selection behavior in parasitoid wasps.

    PubMed

    Zchori-Fein, E; Gottlieb, Y; Kelly, S E; Brown, J K; Wilson, J M; Karr, T L; Hunter, M S

    2001-10-23

    The symbiotic bacterium Wolbachia pipientis has been considered unique in its ability to cause multiple reproductive anomalies in its arthropod hosts. Here we report that an undescribed bacterium is vertically transmitted and associated with thelytokous parthenogenetic reproduction in Encarsia, a genus of parasitoid wasps. Although Wolbachia was found in only one of seven parthenogenetic Encarsia populations examined, the "Encarsia bacterium" (EB) was found in the other six. Among seven sexually reproducing populations screened, EB was present in one, and none harbored Wolbachia. Antibiotic treatment did not induce male production in Encarsia pergandiella but changed the oviposition behavior of females. Cured females accepted one host type at the same rate as control females but parasitized significantly fewer of the other host type. Phylogenetic analysis based on the 16S rDNA gene sequence places the EB in a unique clade within the Cytophaga-Flexibacter-Bacteroid group and shows EB is unrelated to the Proteobacteria, where Wolbachia and most other insect symbionts are found. These results imply evolution of the induction of parthenogenesis in a lineage other than Wolbachia. Importantly, these results also suggest that EB may modify the behavior of its wasp carrier in a way that enhances its transmission.

  7. The genetics and evolution of obligate reproductive parasitism in Trichogramma pretiosum infected with parthenogenesis-inducing Wolbachia

    PubMed Central

    Russell, J E; Stouthamer, R

    2011-01-01

    Parthenogenesis-inducing (PI) Wolbachia belong to a class of intracellular symbionts that distort the offspring sex ratio of their hosts toward a female bias. In many PI Wolbachia-infected species sex ratio distortion has reached its ultimate expression-fixation of infection and all-female populations. This is only possible with thelytokous PI symbionts as they provide an alternative form of reproduction and remove the requirement for males and sexual reproduction. Many populations fixed for PI Wolbachia infection have lost the ability to reproduce sexually, even when cured of the infection. We examine one such population in the species Trichogramma pretiosum. Through a series of backcrossing experiments with an uninfected Trichogramma pretiosum population we were able to show that the genetic basis for the loss of female sexual function could be explained by a dominant nuclear effect. Male sexual function had not been completely lost, though some deterioration of male sexual function was also evident when males from the infected population (created through antibiotic curing of infected females) were mated to uninfected females. We discuss the dynamics of sex ratio selection in PI Wolbachia-infected populations and the evolution of non-fertilizing mutations. PMID:20442735

  8. A single mutation results in diploid gamete formation and parthenogenesis in a Drosophila yemanuclein-alpha meiosis I defective mutant

    PubMed Central

    2010-01-01

    Background Sexual reproduction relies on two key events: formation of cells with a haploid genome (the gametes) and restoration of diploidy after fertilization. Therefore the underlying mechanisms must have been evolutionary linked and there is a need for evidence that could support such a model. Results We describe the identification and the characterization of yem1, the first yem-alpha mutant allele (V478E), which to some extent affects diploidy reduction and its restoration. Yem-alpha is a member of the Ubinuclein/HPC2 family of proteins that have recently been implicated in playing roles in chromatin remodeling in concert with HIRA histone chaperone. The yem1 mutant females exhibited disrupted chromosome behavior in the first meiotic division and produced very low numbers of viable progeny. Unexpectedly these progeny did not display paternal chromosome markers, suggesting that they developed from diploid gametes that underwent gynogenesis, a form of parthenogenesis that requires fertilization. Conclusions We focus here on the analysis of the meiotic defects exhibited by yem1 oocytes that could account for the formation of diploid gametes. Our results suggest that yem1 affects chromosome segregation presumably by affecting kinetochores function in the first meiotic division. This work paves the way to further investigations on the evolution of the mechanisms that support sexual reproduction. PMID:21080953

  9. The genetics and evolution of obligate reproductive parasitism in Trichogramma pretiosum infected with parthenogenesis-inducing Wolbachia.

    PubMed

    Russell, J E; Stouthamer, R

    2011-01-01

    Parthenogenesis-inducing (PI) Wolbachia belong to a class of intracellular symbionts that distort the offspring sex ratio of their hosts toward a female bias. In many PI Wolbachia-infected species sex ratio distortion has reached its ultimate expression-fixation of infection and all-female populations. This is only possible with thelytokous PI symbionts as they provide an alternative form of reproduction and remove the requirement for males and sexual reproduction. Many populations fixed for PI Wolbachia infection have lost the ability to reproduce sexually, even when cured of the infection. We examine one such population in the species Trichogramma pretiosum. Through a series of backcrossing experiments with an uninfected Trichogramma pretiosum population we were able to show that the genetic basis for the loss of female sexual function could be explained by a dominant nuclear effect. Male sexual function had not been completely lost, though some deterioration of male sexual function was also evident when males from the infected population (created through antibiotic curing of infected females) were mated to uninfected females. We discuss the dynamics of sex ratio selection in PI Wolbachia-infected populations and the evolution of non-fertilizing mutations.

  10. Survival and Reproductive Strategies in Two-Spotted Spider Mites: Demographic Analysis of Arrhenotokous Parthenogenesis of Tetranychus urticae (Acari: Tetranychidae).

    PubMed

    Tuan, Shu-Jen; Lin, Yung-Hsiang; Yang, Chung-Ming; Atlihan, Remzi; Saska, Pavel; Chi, Hsin

    2016-04-01

    Tetranychus urticae Koch is a cosmopolitan pest whose rapid developmental rate enables it to produce colonies of thousands of individuals within a short time period. When a solitary virgin female colonizes a new host plant, it is capable of producing male offspring through the arrhenotokous parthenogenesis; once her sons mature, oedipal mating occurs and the female will produce bisexual offspring. To analyze the effect of arrhenotokous reproduction on population growth, we devised and compared separate life tables for arrhenotokous and bisexual populations of T. urticae using the age-stage, two-sex life table theory. For the cohort with bisexual reproduction, the intrinsic rate of increase (r), finite rate (λ), net reproductive rate (R0), and mean generation time (T) were 0.2736 d(−1), 1.3146 d(−1), 44.66 offspring, and 13.89 d, respectively. Because only male eggs were produced during the first 8 d of the oviposition period and the cohort would soon begin bisexual reproduction, it would be theoretically wrong to calculate the population parameters using the survival rate and fecundity of an arrhenotokous cohort. We demonstrated that the effect of arrhenotokous reproduction could be accurately described and evaluated using the age-stage, two-sex life table. We also used population projection based on life table data, quantitatively showing the effect that arrhenotokous reproduction has on the growth potential and management of T. urticae.

  11. A single mutation results in diploid gamete formation and parthenogenesis in a Drosophila yemanuclein-alpha meiosis I defective mutant.

    PubMed

    Meyer, Régis E; Delaage, Michèle; Rosset, Roland; Capri, Michèle; Aït-Ahmed, Ounissa

    2010-11-16

    Sexual reproduction relies on two key events: formation of cells with a haploid genome (the gametes) and restoration of diploidy after fertilization. Therefore the underlying mechanisms must have been evolutionary linked and there is a need for evidence that could support such a model. We describe the identification and the characterization of yem1, the first yem-alpha mutant allele (V478E), which to some extent affects diploidy reduction and its restoration. Yem-alpha is a member of the Ubinuclein/HPC2 family of proteins that have recently been implicated in playing roles in chromatin remodeling in concert with HIRA histone chaperone. The yem1 mutant females exhibited disrupted chromosome behavior in the first meiotic division and produced very low numbers of viable progeny. Unexpectedly these progeny did not display paternal chromosome markers, suggesting that they developed from diploid gametes that underwent gynogenesis, a form of parthenogenesis that requires fertilization. We focus here on the analysis of the meiotic defects exhibited by yem1 oocytes that could account for the formation of diploid gametes. Our results suggest that yem1 affects chromosome segregation presumably by affecting kinetochores function in the first meiotic division. This work paves the way to further investigations on the evolution of the mechanisms that support sexual reproduction.

  12. Geographic Information Office

    USGS Publications Warehouse

    ,

    2004-01-01

    The Geographic Information Office (GIO) is the principal information office for U.S. Geological Survey (USGS), focused on: Information Policy and Services, Information Technology, Science Information, Information Security, and the Federal Geographic Data Committee/Geospatial One Stop.

  13. Geographic Media Literacy

    ERIC Educational Resources Information Center

    Lukinbeal, Chris

    2014-01-01

    While the use of media permeates geographic research and pedagogic practice, the underlying literacies that link geography and media remain uncharted. This article argues that geographic media literacy incorporates visual literacy, information technology literacy, information literacy, and media literacy. Geographic media literacy is the ability…

  14. 33 CFR 167.3 - Geographic coordinates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Geographic coordinates. 167.3 Section 167.3 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY OFFSHORE TRAFFIC SEPARATION SCHEMES General § 167.3 Geographic coordinates...

  15. The effects of outbreeding on a parasitoid wasp fixed for infection with a parthenogenesis-inducing Wolbachia symbiont.

    PubMed

    Lindsey, A R I; Stouthamer, R

    2017-12-01

    Trichogramma wasps can be rendered asexual by infection with the maternally inherited symbiont Wolbachia. Previous studies indicate the Wolbachia strains infecting Trichogramma wasps are host-specific, inferred by failed horizontal transfer of Wolbachia to novel Trichogramma hosts. Additionally, Trichogramma can become dependent upon their Wolbachia infection for the production of female offspring, leaving them irreversibly asexual, further linking host and symbiont. We hypothesized Wolbachia strains infecting irreversibly asexual, resistant to horizontal transfer Trichogramma would show adaptation to a particular host genetic background. To test this, we mated Wolbachia-dependent females with males from a Wolbachia-naïve population to create heterozygous wasps. We measured sex ratios and fecundity, a proxy for Wolbachia fitness, produced by heterozygous wasps, and by their recombinant offspring. We find a heterozygote advantage, resulting in higher fitness for Wolbachia, as wasps will produce more offspring without any reduction in the proportion of females. While recombinant wasps did not differ in total fecundity after 10 days, recombinants produced fewer offspring early on, leading to an increased female-biased sex ratio for the whole brood. Despite the previously identified barriers to horizontal transfer of Wolbachia to and from Trichogramma pretiosum, there were no apparent barriers for Wolbachia to induce parthenogenesis in these non-native backgrounds. This is likely due to the route of infection being introgression rather than horizontal transfer, and possibly the co-evolution of Wolbachia with the mitochondria rather than the nuclear genome. These results help to elucidate the mechanisms by which Wolbachia adapt to hosts and the evolution of host-symbiont phenotypes.

  16. Novel microsatellite DNA markers indicate strict parthenogenesis and few genotypes in the invasive willow sawfly Nematus oligospilus.

    PubMed

    Caron, V; Norgate, M; Ede, F J; Nyman, T; Sunnucks, P

    2013-02-01

    Invasive organisms can have major impacts on the environment. Some invasive organisms are parthenogenetic in their invasive range and, therefore, exist as a number of asexual lineages (=clones). Determining the reproductive mode of invasive species has important implications for understanding the evolutionary genetics of such species, more especially, for management-relevant traits. The willow sawfly Nematus oligospilus Förster (Hymenoptera: Tenthredinidae) has been introduced unintentionally into several countries in the Southern Hemisphere where it has subsequently become invasive. To assess the population expansion, reproductive mode and host-plant relationships of this insect, microsatellite markers were developed and applied to natural populations sampled from the native and expanded range, along with sequencing of the cytochrome-oxidase I mitochondrial DNA (mtDNA) region. Other tenthredinids across a spectrum of taxonomic similarity to N. oligospilus and having a range of life strategies were also tested. Strict parthenogenesis was apparent within invasive N. oligospilus populations throughout the Southern Hemisphere, which comprised only a small number of genotypes. Sequences of mtDNA were identical for all individuals tested in the invasive range. The microsatellite markers were used successfully in several sawfly species, especially Nematus spp. and other genera of the Nematini tribe, with the degree of success inversely related to genetic divergence as estimated from COI sequences. The confirmation of parthenogenetic reproduction in N. oligospilus and the fact that it has a very limited pool of genotypes have important implications for understanding and managing this species and its biology, including in terms of phenotypic diversity, host relationships, implications for spread and future adaptive change. It would appear to be an excellent model study system for understanding evolution of invasive parthenogens that diverge without sexual reproduction and

  17. Composing Models of Geographic Physical Processes

    NASA Astrophysics Data System (ADS)

    Hofer, Barbara; Frank, Andrew U.

    Processes are central for geographic information science; yet geographic information systems (GIS) lack capabilities to represent process related information. A prerequisite to including processes in GIS software is a general method to describe geographic processes independently of application disciplines. This paper presents such a method, namely a process description language. The vocabulary of the process description language is derived formally from mathematical models. Physical processes in geography can be described in two equivalent languages: partial differential equations or partial difference equations, where the latter can be shown graphically and used as a method for application specialists to enter their process models. The vocabulary of the process description language comprises components for describing the general behavior of prototypical geographic physical processes. These process components can be composed by basic models of geographic physical processes, which is shown by means of an example.

  18. Review and synthesis of problems and directions for large scale geographic information system development

    NASA Technical Reports Server (NTRS)

    Boyle, A. R.; Dangermond, J.; Marble, D.; Simonett, D. S.; Tomlinson, R. F.

    1983-01-01

    Problems and directions for large scale geographic information system development were reviewed and the general problems associated with automated geographic information systems and spatial data handling were addressed.

  19. Modes of inheritance of two apomixis components, diplospory and parthenogenesis, in Chinese chive (Allium ramosum) revealed by analysis of the segregating population generated by back-crossing between amphimictic and apomictic diploids

    PubMed Central

    Yamashita, Ken-ichiro; Nakazawa, Yoshiko; Namai, Kiyoshi; Amagai, Masayuki; Tsukazaki, Hikaru; Wako, Tadayuki; Kojima, Akio

    2012-01-01

    To investigate the mode of inheritance of apomixis in Chinese chive, the degrees of diplospory and parthenogenesis were evaluated in F1 and BC1 progenies derived from crosses between amphimictic and apomictic diploids (2n = 16, 2x). The F1 population was generated by crossing three amphimictic diploids 94Mo13, 94Mo49 and 94Mo50 with an apomictic diploid KaD2 and comprised 110 diploids and 773 triploids. All the diploid F1 plants examined were completely or highly eusporous and completely syngamic. All the triploid F1 plants examined were highly diplosporous and highly parthenogenetic. KaD2 could not transmit its high level of apomixis via monoploid pollen grains. The BC1 population, generated by crossing 94Mo49 with apomictic triploids found in the F1 offspring, exhibited heteroploidy; it comprised haploid, diploid, triploid, tetraploid and various aneuploid individuals. In this generation, clear segregation was observed between diplospory and parthenogenesis. Analysis of the BC1 population suggests that diplospory and parthenogenesis are each controlled by single dominant genes, D and P, respectively. However, all the BC1 plants characterized as parthenogenetic were diplosporous. The absence of phenotypically eusporous parthenogenetic plants can be explained by assuming that the presence of diplospory gene is a prerequisite for the parthenogenesis gene expression in Chinese chive. PMID:23136527

  20. Geographic Profiling: Knowledge Through Prediction

    DTIC Science & Technology

    2014-06-01

    FTO Foreign Terrorist Organization GIS geographic information systems LE lawless elements MADM multi-attribute decision making MILF Moro Islamic...or her life. Anchor points can include the offender’s home , his or her workplace, a home of a friend of the offender, or even a bar or restaurant...more generally for the improvement of police patrols. In Memphis, TN, city officials have seen a decrease in crime with the help of operation Blue

  1. Evaluation in Geographic Education.

    ERIC Educational Resources Information Center

    Kurfman, Dana G., Ed.

    This second yearbook of the National Council for Geographic Education presents recent thinking about the formulation and assessment of the educational outcomes of geography. Dana G. Kurfman overviews "Evaluation Developments Useful in Geographic Education" relating evaluation to decision making, objectives, data gatherings, and data…

  2. Coloring geographical threshold graphs

    SciTech Connect

    Bradonjic, Milan; Percus, Allon; Muller, Tobias

    We propose a coloring algorithm for sparse random graphs generated by the geographical threshold graph (GTG) model, a generalization of random geometric graphs (RGG). In a GTG, nodes are distributed in a Euclidean space, and edges are assigned according to a threshold function involving the distance between nodes as well as randomly chosen node weights. The motivation for analyzing this model is that many real networks (e.g., wireless networks, the Internet, etc.) need to be studied by using a 'richer' stochastic model (which in this case includes both a distance between nodes and weights on the nodes). Here, we analyzemore » the GTG coloring algorithm together with the graph's clique number, showing formally that in spite of the differences in structure between GTG and RGG, the asymptotic behavior of the chromatic number is identical: {chi}1n 1n n / 1n n (1 + {omicron}(1)). Finally, we consider the leading corrections to this expression, again using the coloring algorithm and clique number to provide bounds on the chromatic number. We show that the gap between the lower and upper bound is within C 1n n / (1n 1n n){sup 2}, and specify the constant C.« less

  3. How patients perceive the therapeutic communications skills of their general practitioners, and how that perception affects adherence: use of the TCom-skill GP scale in a specific geographical area.

    PubMed

    Baumann, Michèle; Baumann, Cédric; Le Bihan, Etienne; Chau, Nearkasen

    2008-12-01

    To study: (1) the structure and test-retest reliability of a measure of how patients perceive the therapeutic communications skills of their general practitioners (TCom-skill GP), and (2) the associations of that scale with socio-demographic and health-related characteristics, and adherence. A total of 393 people who lived in the same geographic area and invited to attend a preventive medical centre for a check up were asked to complete a self-administered questionnaire concerning TCom-skill GP (15 items), socio-demographic and health-related characteristics, and to answer two questions on perceived adherence. The average age of respondents was 46.8 years (SD 14), and 50.4% were men. The TCom-skill GP score was one-dimensional, had high internal coherence (Cronbach alpha 0.92), and good test-retest reliability (intra-class correlation coefficient 0.74). The overall score was positively related to increasing age. Respondents aged 60+ were more likely to be adherent. The higher the score, the higher the probability of adherence. Multivariate analysis showed that the TCom-skill score was associated with advancing age and the number of consultations with the GP during the previous 3 months, but not with gender, living alone, being employed, job category or educational level. Multivariate analysis also showed that adherence was associated with TCom-skill GP score which concealed the association between adherence and advancing age observed in univariate analysis. The TCom-skill GP scale probably has value in assessing the quality of doctor-patient relationships and therapeutic communications. The psychometric properties of the TCom-skill GP scale were appropriate for its use in this context. Adherence related to the TCom-skill GP and the latter related to the age of patients and the number of their previous consultations. The TCom-skill GP scale may be a useful way to assess, in a specific geographical location, the impact of medical professional training on therapeutic

  4. Geographic distribution of physicians in Portugal.

    PubMed

    Isabel, Correia; Paula, Veiga

    2010-08-01

    The main goals of this paper are to (1) analyse the inequality in geographic distribution of physicians and its evolution, (2) estimate the determinants of physician density, and (3) assess the importance of competitive and agglomerative forces in location decisions. The analysis of the geographic distribution of physicians is based on the ratio of general practitioners (GPs) and specialists to 1,000 inhabitants. The inequality is measured using Gini indices, coefficients of variation, and physician-to-population ratios. The econometric models were estimated by ordinary least squares. The data used refer to 1996 and 2007. The impact of the growing number of physicians, and therefore potential increased competition, on geographic distribution during the period studied was small. Nonetheless, there is evidence of competitive forces acting on the dynamics of doctor localisation. Geographic disparities in physician density are still high, and appear to be due mainly to geographic income inequality.

  5. Sexually antagonistic coevolution for sexual harassment can act as a barrier to further invasions by parthenogenesis.

    PubMed

    Kawatsu, Kazutaka

    2013-02-01

    The assumption of a twofold cost of sex not only complicates the maintenance of sex but also sets conditions for sexual conflict: in organisms with the twofold cost, males often sexually harass females. Sexual harassment is detrimental to female fitness and thus might help maintain sexual populations if male harassment inflicts a harsher cost on parthenogens than on sexual females (asymmetric harassment cost). However, the generality of this concept is now considered doubtful because selective harassment of parthenogens results in loss of mating opportunities for males. Using three mathematical models, I show here that sexual harassment still can impose the asymmetric cost on parthenogens. First, I apply the Lotka-Volterra model to show the degree of asymmetric harassment cost that permits sex to be maintained stably in the population. Second, using adaptive dynamics, I examine whether sexually antagonistic coevolution for sexual harassment, which occurs only in sexual populations, can promote the asymmetric harassment cost. Finally, an individual-based model, which assumes a spatial structure unlike that in the other two, demonstrates that the asymmetric evolution of harassment cost prevents further invasions of parthenogens from different patches into sexual lineages; these mechanisms may account for allopatric distributions of sexual and parthenogenetic lineages as well as the maintenance of sex.

  6. On human parthenogenesis.

    PubMed

    Jose de Carli, Gabriel; Campos Pereira, Tiago

    2017-09-01

    Spontaneous parthenogenetic and androgenetic events occur in humans, but they result in tumours: the ovarian teratoma and the hydatidiform mole, respectively. However, the observation of fetiform (ovarian) teratomas, the serependious identification of several chimeric human parthenotes and androgenotes in the last two decades, along with the creation of viable bi-maternal mice in the laboratory based on minor genetic interferences, raises the question of whether natural cases of clinically healthy human parthenotes have gone unnoticed to science. Here we present a hypothesis based on three elements to support the existence of such elusive individuals: mutations affecting (i) genomic imprinting, (ii) meiosis and (iii) oocyte activation. Additionally, we suggest that the routine practice of whole genome sequencing on every single newborn worldwide will be the ultimate test to this controversial, yet astonishing hypothesis. Finally, several medical implications of such intriguing event are presented. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Symposium on Geographic Information Systems.

    ERIC Educational Resources Information Center

    Felleman, John, Ed.

    1990-01-01

    Six papers on geographic information systems cover the future of geographic information systems, land information systems modernization in Wisconsin, the Topologically Integrated Geographic Encoding and Referencing (TIGER) System of the U.S. Bureau of the Census, satellite remote sensing, geographic information systems and sustainable development,…

  8. Making Geographical Futures

    ERIC Educational Resources Information Center

    Morgan, John

    2015-01-01

    Although there are surprisingly few academic books about geography with the term "future" or "futures" in their titles, this paper indicates that for much of the twentieth century geographers contributed to important discussions about the shape of worlds to come. The paper offers a review of these debates within Anglo-American…

  9. Geographic Education in Louisiana

    ERIC Educational Resources Information Center

    Lewis, Anthony J.

    2004-01-01

    In this article, the author analyzes and summarizes geographic education in Louisiana from a historical perspective with a specific emphasis on the degree to which geography was implemented into the state's standards. To accomplish that, he draws from the following three sources of information: active and retired social studies teachers from a…

  10. Minimum variance geographic sampling

    NASA Technical Reports Server (NTRS)

    Terrell, G. R. (Principal Investigator)

    1980-01-01

    Resource inventories require samples with geographical scatter, sometimes not as widely spaced as would be hoped. A simple model of correlation over distances is used to create a minimum variance unbiased estimate population means. The fitting procedure is illustrated from data used to estimate Missouri corn acreage.

  11. Geographic data from space

    USGS Publications Warehouse

    Alexander, Robert H.

    1964-01-01

    Space science has been called “the collection of scientific problems to which space vehicles can make some specific contributions not achievable by ground-based experiments.” Geography, the most spatial of the sciences, has now been marked as one of these “space sciences.” The National Aeronautics and Space Administration (NASA) is sponsoring an investigation to identify the Potential geographic benefits from the nation’s space program. This is part of NASA’s long-range inquiry to determine the kinds of scientific activities which might profitably be carried out on future space missions. Among such future activities which are now being planned by NASA are a series of manned earth orbital missions, many of which would be devoted to research. Experiments in physics, astronomy, geophysics, meteorology, and biology are being discussed for these long-range missions. The question which is being put to geographers is, essentially, what would it mean to geographic research to have an observation satellite (or many such satellites) orbiting the earth, gathering data about earth-surface features and environments?

  12. Estimating tree species diversity across geographic scales

    Treesearch

    Susanne Winter; Andreas Böck; Ronald E. McRoberts

    2012-01-01

    The relationship between number of species and area observed has been described using numerous approaches and has been discussed for more than a century. The general objectives of our study were fourfold: (1) to evaluate the behaviour of species-area curves across geographic scales, (2) to determine sample sizes necessary to produce acceptably precise estimates of tree...

  13. Natural Scales in Geographical Patterns

    NASA Astrophysics Data System (ADS)

    Menezes, Telmo; Roth, Camille

    2017-04-01

    Human mobility is known to be distributed across several orders of magnitude of physical distances, which makes it generally difficult to endogenously find or define typical and meaningful scales. Relevant analyses, from movements to geographical partitions, seem to be relative to some ad-hoc scale, or no scale at all. Relying on geotagged data collected from photo-sharing social media, we apply community detection to movement networks constrained by increasing percentiles of the distance distribution. Using a simple parameter-free discontinuity detection algorithm, we discover clear phase transitions in the community partition space. The detection of these phases constitutes the first objective method of characterising endogenous, natural scales of human movement. Our study covers nine regions, ranging from cities to countries of various sizes and a transnational area. For all regions, the number of natural scales is remarkably low (2 or 3). Further, our results hint at scale-related behaviours rather than scale-related users. The partitions of the natural scales allow us to draw discrete multi-scale geographical boundaries, potentially capable of providing key insights in fields such as epidemiology or cultural contagion where the introduction of spatial boundaries is pivotal.

  14. The ARC/INFO geographic information system

    NASA Astrophysics Data System (ADS)

    Morehouse, Scott

    1992-05-01

    ARC/INFO is a general-purpose system for processing geographic information. It is based on a relatively simple model of geographic space—the coverage—and contains an extensive set of geoprocessing tools which operate on coverages. ARC/INFO is used in a wide variety of applications areas, including: natural-resource inventory and planning, cadastral database development and mapping, urban and regional planning, and cartography. This paper is an overview of ARC/INFO and discusses the ARC/INFO conceptual architecture, data model, operators, and user interface.

  15. Volunteered Geographic Information in Wikipedia

    ERIC Educational Resources Information Center

    Hardy, Darren

    2010-01-01

    Volunteered geographic information (VGI) refers to the geographic subset of online user-generated content. Through Geobrowsers and online mapping services, which use geovisualization and Web technologies to share and produce VGI, a global digital commons of geographic information has emerged. A notable example is Wikipedia, an online collaborative…

  16. Synergetic Paradigm of Geographical Science

    ERIC Educational Resources Information Center

    Gorbanyov, Vladimir A.

    2016-01-01

    It is shown that in the last decades, geography has expanded so much, that it has lost its object of study. It was not clear, what the geographical science does, and, as a consequence, households have an extremely low level of geographical cultures and geographical education. Each geography is extremely isolated, has its own object of study.…

  17. GEOGRAPHIC NAMES INFORMATION SYSTEM (GNIS)

    EPA Science Inventory

    The Geographic Names Information System (GNIS), developed by the U.S. Geological Survey in cooperation with the U.S. Board on Geographic Names (BGN), contains information about physical and cultural geographic features in the United States and associated areas, both current and h...

  18. The National Map - Geographic Names

    USGS Publications Warehouse

    ,

    2002-01-01

    Governments depend on a common set of base geographic information as a tool for economic and community development, land and natural resource management, and health and safety services. Emergency management and homeland security applications rely on this information. Private industry, nongovernmental organizations, and individual citizens use the same geographic data. Geographic information underpins an increasingly large part of the Nation's economy.

  19. Molecular phylogeny, biogeography and insights into the origin of parthenogenesis in the Neotropical genus Leposoma (Squamata: Gymnophthalmidae): Ancient links between the Atlantic Forest and Amazonia.

    PubMed

    Pellegrino, Katia C M; Rodrigues, Miguel T; Harris, D James; Yonenaga-Yassuda, Yatiyo; Sites, Jack W

    2011-11-01

    Leposoma is a conspicuous component of leaf litter herpetofauna of South and Central American rainforests. The 15 bisexual and one parthenogenetic species are allocated to the parietale and scincoides groups based on morphology. Phylogenetic analyses of 1830 bp (mtDNA+nuclear) were performed on 63 specimens of four species from Amazonian and Panamanian rainforests, and six species and one undescribed form from the Atlantic Forest. Different methods of tree reconstruction were explored, with Anotosaura vanzolinia and Colobosauroides cearensis as outgroups. The monophyly of the parietale and scincoides groups is strongly supported. Contrary to previous hypotheses suggesting a recent contact between Atlantic and Amazon forests, our estimates point to an initial split in Miocene. The position of Leposoma baturitensis, endemic to relictual forests in the semiarid Caatingas northeastern Brazil, and its divergence from the remaining species of the Atlantic Forest, suggests an ancient isolation with no indication of a secondary contact with forests of the eastern coast. Our data do not permit unambiguous assignment of parental species of the unisexual Leposoma percarinatum or the mechanism involved in the origin of parthenogenesis, but revealed two highly divergent diploid and triploid lineages within L. percarinatum, indicating that the unisexuals represent a species complex. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Developing Trainee Teacher Practice with Geographical Information Systems (GIS)

    ERIC Educational Resources Information Center

    Walshe, Nicola

    2017-01-01

    There is general agreement that geographical information systems (GIS) have a place within the geography classroom; they offer the potential to support geographical learning, exploring real-world problems through student-centred learning, and developing spatial thinking. Despite this, teachers often avoid engaging with GIS and research suggests…

  1. Patterns and causes of geographic variation in bat echolocation pulses.

    PubMed

    Jiang, Tinglei; Wu, Hui; Feng, Jiang

    2015-05-01

    Evolutionary biologists have a long-standing interest in how acoustic signals in animals vary geographically, because divergent ecology and sensory perception play an important role in speciation. Geographic comparisons are valuable in determining the factors that influence divergence of acoustic signals. Bats are social mammals and they depend mainly on echolocation pulses to locate prey, to navigate and to communicate. Mounting evidence shows that geographic variation of bat echolocation pulses is common, with a mean 5-10 kHz differences in peak frequency, and a high level of individual variation may be nested in this geographical variation. However, understanding the geographic variation of echolocation pulses in bats is very difficult, because of differences in sample and statistical analysis techniques as well as the variety of factors shaping the vocal geographic evolution. Geographic differences in echolocation pulses of bats generally lack latitudinal, longitudinal and elevational patterns, and little is known about vocal dialects. Evidence is accumulating to support the fact that geographic variation in echolocation pulses of bats may be caused by genetic drift, cultural drift, ecological selection, sexual selection and social selection. Future studies could relate geographic differences in echolocation pulses to social adaptation, vocal learning strategies and patterns of dispersal. In addition, new statistical techniques and acoustic playback experiments may help to illustrate the causes and consequences of the geographic evolution of echolocation pulse in bats. © 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

  2. GEOGRAPHIC NAMES INFORMATION SYSTEM (GNIS) ...

    EPA Pesticide Factsheets

    The Geographic Names Information System (GNIS), developed by the U.S. Geological Survey in cooperation with the U.S. Board on Geographic Names (BGN), contains information about physical and cultural geographic features in the United States and associated areas, both current and historical, but not including roads and highways. The database also contains geographic names in Antarctica. The database holds the Federally recognized name of each feature and defines the location of the feature by state, county, USGS topographic map, and geographic coordinates. Other feature attributes include names or spellings other than the official name, feature designations, feature class, historical and descriptive information, and for some categories of features the geometric boundaries. The database assigns a unique feature identifier, a random number, that is a key for accessing, integrating, or reconciling GNIS data with other data sets. The GNIS is our Nation's official repository of domestic geographic feature names information.

  3. Geographically correlated orbit error

    NASA Technical Reports Server (NTRS)

    Rosborough, G. W.

    1989-01-01

    The dominant error source in estimating the orbital position of a satellite from ground based tracking data is the modeling of the Earth's gravity field. The resulting orbit error due to gravity field model errors are predominantly long wavelength in nature. This results in an orbit error signature that is strongly correlated over distances on the size of ocean basins. Anderle and Hoskin (1977) have shown that the orbit error along a given ground track also is correlated to some degree with the orbit error along adjacent ground tracks. This cross track correlation is verified here and is found to be significant out to nearly 1000 kilometers in the case of TOPEX/POSEIDON when using the GEM-T1 gravity model. Finally, it was determined that even the orbit error at points where ascending and descending ground traces cross is somewhat correlated. The implication of these various correlations is that the orbit error due to gravity error is geographically correlated. Such correlations have direct implications when using altimetry to recover oceanographic signals.

  4. Geographical Database Integrity Validation

    NASA Technical Reports Server (NTRS)

    Jacobs, Derya; Kauffman, Paul; Blackstock, Dexter

    2000-01-01

    Airport Safety Modeling Data (ASMD) was developed at the request of a 1997 White House Conference on Aviation Safety and Security. Politicians, military personnel, commercial aircraft manufacturers and the airline industry attended the conference. The objective of the conference was to study the airline industry and make recommendations to improve safety and security. One of the topics discussed at the conference was the loss of situational awareness by aircraft pilots. Loss of situational awareness occurs when a pilot loses his geographic position during flight and can result in crashes into terrain and obstacles. It was recognized at the conference that aviation safety could be improved by reducing the loss of situational awareness. The conference advised that a system be placed in the airplane cockpit that would provide pilots with a visual representation of the terrain around airports. The system would prevent airline crashes during times of inclement weather and loss of situational awareness. The system must be based on accurate data that represents terrain around airports. The Department of Defense and the National Imagery and Mapping Agency (NIMA) released ASMD to be used for the development of a visual system for aircraft pilots. ASMD was constructed from NIMA digital terrain elevation data (DTED).

  5. Female parthenogenetic apomixis and androsporogenetic parthenogenesis in embryonal cells of Araucaria angustifolia: interpolation of progenesis and asexual heterospory in an artificial sporangium.

    PubMed

    Durzan, Don J

    2012-09-01

    Cell fate, development timing and occurrence of reproductive versus apomictic development in gymnosperms are shown to be influenced by culture conditions in vitro. In this study, female parthenogenetic apomixis (fPA), androsporogenetic parthenogenesis (mAP) and progenesis were demonstrated using embryonal initials of Araucaria angustifolia in scaled-up cell suspensions passing through a single-cell bottleneck in darkness and in an artificial sporangium (AS). Expression was based on defined nutrition, hormones and feedforward-adaptive feedback process controls at 23-25 °C and in darkness. In fPA, the nucleus of an embryonal initial undergoes endomitosis and amitosis, forming a diploid egg-equivalent and an apoptotic ventral canal nucleus in a transdifferentiated archegonial tube. Discharge of egg-equivalent cells as parthenospores and their dispersal into the aqueous culture medium were followed by free-nuclear conifer-type proembryogenesis. This replaced the plesiomorphic and central features of proembryogenesis in Araucariaceae. Protoplasmic fusions of embryonal initials were used to reconstruct heterokaryotic expressions of fPA in multiwell plates. In mAP, restitutional meiosis (automixis) was responsible for androsporogenesis and the discharge of monads, dyads, tetrads and polyads. In a display of progenesis, reproductive development was brought to an earlier ontogenetic stage and expressed by embryonal initials. Colchicine increased polyploidy, but androspore formation became aberrant and fragmented. Aberrant automixis led to the formation of chromosomal bouquets, which contributed to genomic silencing in embryonal initials, cytomixis and the formation of pycnotic micronucleated cells. Dispersal of female and male parthenospores displayed heteromorphic asexual heterospory in an aqueous environment.

  6. Adding complexity to the complex: new insights into the phylogeny, diversification and origin of parthenogenesis in the Aporrectodea caliginosa species complex (Oligochaeta, Lumbricidae).

    PubMed

    Fernández, Rosa; Almodóvar, Ana; Novo, Marta; Simancas, Bárbara; Díaz Cosín, Darío J

    2012-08-01

    The importance of the Aporrectodea caliginosa species complex lies in the great abundance and wide distribution of the species which exist within it. For more than a century, chaos has surrounded this complex; morphological criteria has failed to solve the taxonomic status of these species. This present body of work aims to study the phylogeny of this complex by increasing the number of samples used in previous molecular works and by including morphologically-similar species that were never studied using molecular tools (A. giardi, Nicodrilus monticola, N. carochensis and N. tetramammalis). Two basal clades were obtained: one formed by A. caliginosa and A. tuberculata and the other by the rest of the species. This second clade was divided into two more: one with Eurosiberian and another with Mediterranean forms. A. caliginosa and A. longa were divided into two paraphyletic groups. Both A. giardi and A. nocturna showed characteristics consistent with monophyletic groups. Each of the two recovered lineages of A. trapezoides were phylogenetically related to different sexual species. While lineage I of A. trapezoides was monophyletic, lineage II resulted to be paraphyletic, as well as the three Nicodrilus 'species'. The diversification of the complex occurred during the Late Miocene-Early Pliocene (6.92-11.09 Mya). The parthenogenetic forms within the Mediterranean clade would have diversified before the ones in the Eurosiberian clade (3.13-4.64 Mya and 1.05-3.48 Mya, respectively), thus implying the existence not only of at least two different moments in which parthenogenesis arose within this complex of species, but also of two different and independent evolutionary lines. Neither the 4× rule nor the GMYC method for species delimitation were successful for distinguishing taxonomically-distinct species. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Pig oocytes with a large perivitelline space matured in vitro show greater developmental competence after parthenogenesis and somatic cell nuclear transfer.

    PubMed

    Lee, Joohyeong; You, Jinyoung; Lee, Geun-Shik; Hyun, Sang-Hwan; Lee, Eunsong

    2013-09-01

    The objective of this study was to examine the developmental competence of pig oocytes in relation to the size of the perivitelline space (PVS) of oocytes matured in vitro. Immature oocytes were matured in medium 199 or porcine zygote medium (PZM)-3 containing 108 or 61.6 mM NaCl. In vitro-matured (IVM) oocytes were examined for intracellular glutathione (GSH) level; cyclin-dependent kinase 1 (CDK1), proliferating cell nuclear antigen (PCNA), and extracellular signal-regulated kinase 2 (ERK2) mRNA levels; and developmental competence after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT). IVM oocytes with a larger PVS had higher (P < 0.05) levels of intracellular GSH (1.00 pixels/oocyte vs. 0.57 pixels/oocyte) and blastocyst formation (54.3% vs. 37.3%) after PA than oocytes with a smaller PVS. Culturing oocytes for maturation in PZM-3 with reduced (61.6 mM) NaCl increased (P < 0.05) the size of the PVS (6.4 µm vs. 2.8 µm) compared to control oocytes that were matured in normal PZM-3 containing 108 mM NaCl. Moreover, oocytes with a larger PVS showed higher CDK1, PCNA, and ERK2 mRNA and intracellular GSH levels (1.6 pixels/oocyte vs. 1.2 pixels/oocyte) and increased blastocyst formation after PA (52.1% vs. 40.6%) and SCNT (31.8% vs. 18.2%) than control oocytes. Our results demonstrate that pig oocytes with a large PVS have greater developmental competence after PA and SCNT, which is attributed to improved cytoplasmic maturation based on the enhanced GSH level and transcription factor expression. Further, enlargement of the PVS by culturing in low-NaCl medium improves the developmental competence of pig oocytes. Copyright © 2013 Wiley Periodicals, Inc.

  8. Determinants of Dentists' Geographic Distribution.

    ERIC Educational Resources Information Center

    Beazoglou, Tryfon J.; And Others

    1992-01-01

    A model for explaining the geographic distribution of dentists' practice locations is presented and applied to particular market areas in Connecticut. Results show geographic distribution is significantly related to a few key variables, including demography, disposable income, and housing prices. Implications for helping students make practice…

  9. Geographic information systems: introduction.

    PubMed

    Calistri, Paolo; Conte, Annamaria; Freier, Jerome E; Ward, Michael P

    2007-01-01

    The recent exponential growth of the science and technology of geographic information systems (GIS) has made a tremendous contribution to epidemiological analysis and has led to the development of new powerful tools for the surveillance of animal diseases. GIS, spatial analysis and remote sensing provide valuable methods to collect and manage information for epidemiological surveys. Spatial patterns and trends of disease can be correlated with climatic and environmental information, thus contributing to a better understanding of the links between disease processes and explanatory spatial variables. Until recently, these tools were underexploited in the field of veterinary public health, due to the prohibitive cost of hardware and the complexity of GIS software that required a high level of expertise. The revolutionary developments in computer performance of the last decade have not only reduced the costs of equipment but have made available easy-to-use Web-based software which in turn have meant that GIS are more widely accessible by veterinary services at all levels. At the same time, the increased awareness of the possibilities offered by these tools has created new opportunities for decision-makers to enhance their planning, analysis and monitoring capabilities. These technologies offer a new way of sharing and accessing spatial and non-spatial data across groups and institutions. The series of papers included in this compilation aim to: - define the state of the art in the use of GIS in veterinary activities - identify priority needs in the development of new GIS tools at the international level for the surveillance of animal diseases and zoonoses - define practical proposals for their implementation. The topics addressed are presented in the following order in this book: - importance of GIS for the monitoring of animal diseases and zoonoses - GIS application in surveillance activities - spatial analysis in veterinary epidemiology - data collection and remote

  10. Geographical and taxonomic biases in invasion ecology.

    PubMed

    Pysek, Petr; Richardson, David M; Pergl, Jan; Jarosík, Vojtech; Sixtová, Zuzana; Weber, Ewald

    2008-05-01

    Invasive alien species come from most taxonomic groups, and invasion biology is searching for robust cross-taxon generalizations and principles. An analysis of 2,670 papers dealing with 892 invasive species showed that all major groups of invaders are well studied, but that most information on the mechanisms of invasion has emerged from work on a limited number of the most harmful invaders. A strong geographical bias, with Africa and Asia understudied, inhibits a balanced understanding of invasion, because we might be lacking knowledge of specific invasion mechanisms from poorly studied, regionally specific habitats. International cooperation is required to achieve a more geographically balanced picture of biological invasions. Invasive species with the greatest impact are best studied, but more studies of species that are naturalized but not (yet) invasive are needed to improve understanding of the mechanisms acting during the naturalization phase of invasions and leading to successful invasion.

  11. Geographic Education for Spaceship Earth

    ERIC Educational Resources Information Center

    Blachford, Kevin

    1974-01-01

    Six unsatisfactory ways of approaching geographic concepts in the classroom are presented. An alternative that would promote global-mindedness and the development of accurate mental maps in students is discussed in terms of teaching techniques. (JH)

  12. Reproductive biology and species geographical distribution in the Melastomataceae: a survey based on New World taxa

    PubMed Central

    dos Santos, Ana Paula Milla; Fracasso, Carla Magioni; Luciene dos Santos, Mirley; Romero, Rosana; Sazima, Marlies; Oliveira, Paulo Eugênio

    2012-01-01

    distributed. This is, to a certain extent, similar to the geographical parthenogenesis pattern of temperate apomictics. PMID:22751617

  13. The National Map - geographic names

    USGS Publications Warehouse

    Yost, Lou; Carswell, William J.

    2009-01-01

    The Geographic Names Information System (GNIS), developed by the U.S. Geological Survey (USGS) in cooperation with the U.S. Board on Geographic Names (BGN), contains information about the official names for places, features, and areas in the 50 States, the District of Columbia, the territories and outlying areas of the United States, including Antarctica. It is the geographic names component of The National Map. The BGN maintains working relationships with State names authorities to cooperate in achieving the standardization of geographic names. The GNIS contains records on more than 2 million geographic names in the United States - from populated places, schools, reservoirs, and parks to streams, valleys, springs, ridges, and every feature type except roads and highways. Entries include information such as the federally-recognized name and variant names and spellings for the feature; former names; the status of the name as determined by the BGN; county or counties in which each named feature is located; geographic coordinates that locate the approximate center of an aerial feature or the mouth and source of a linear feature, such as a stream; name of the cell of the USGS topographic map or maps on which the feature may appear; elevation figures derived from the National Elevation Dataset; bibliographic code for the source of the name; BGN decision dates and historical information are available for some features. Data from the GNIS are used for emergency preparedness, mapmaking, local and regional planning, service delivery routing, marketing, site selection, environmental analysis, genealogical research, and other applications.

  14. Absence of Sperm Factors as in the Parthenogenesis Does Not Interfere on Bovine Embryo Sensitiveness to Heat Shock at Pre-Implantation Stage.

    PubMed

    Camargo, L S A; Paludo, F; Pereira, M M; Wohlres-Viana, S; Gioso, M M; Carvalho, B C; Quintao, C C R; Viana, J H M

    2016-02-01

    Oocyte has been considered the major contributor for embryo thermo-tolerance. However, it was shown that sperm factors can be transferred to the oocyte during fertilization, raising the question of whether the absence of such factors could interfere on embryo thermo-tolerance. In this study, we used parthenogenesis to generate bovine embryos without spermatozoa in order to test whether the absence of sperm factors could influence their thermo-sensitiveness at early stages. In vitro fertilized (IVF) and parthenogenetic (PA) embryos at 44 h post-insemination/chemical activation were exposed to 38.5°C (control) or 41°C (heat shock) for 12 h and then developed for 48 h and up to blastocyst stage. Apoptosis index and expression of PRDX1, GLUT1, GLUT5 and IGF1r genes in blastocysts derived from heat-shocked embryos were also evaluated. The heat shock decreased the blastocyst rate at day seven (p < 0.05) for IVF embryos and at day eight (p < 0.01) for both IVF and PA embryos. Total cell number was not affected by heat shock in IVF and PA blastocysts, but there was an increased proportion (p < 0.05) of apoptotic cells in heat-shocked embryos when compared to controls. There was no interaction (p > 0.05) between method of activation (IVF and PA) and temperature (38.5°C or 41.5°C) for all developmental parameters evaluated. Expression of GLUT1 gene was downregulated (p < 0.05) by heat shock in both IVF and PA blastocyst whereas expression of GLUT5 and IGF1r genes was downregulated (p < 0.05) by heat shock in PA blastocysts. Those data show that the heat shock affects negatively the embryo development towards blastocysts stage, increases the apoptotic index and disturbed the expression of some genes in both IVF and PA embryos, indicating that the presence or absence of sperm factors does not influence the sensitivity of the bovine embryo to heat shock. © 2015 Blackwell Verlag GmbH.

  15. High prevalence of stroke symptoms among persons without a diagnosis of stroke or transient ischemic attack in a general population: the REasons for Geographic And Racial Differences in Stroke (REGARDS) study.

    PubMed

    Howard, Virginia J; McClure, Leslie A; Meschia, James F; Pulley, Leavonne; Orr, Sean C; Friday, Gary H

    2006-10-09

    A substantial portion of the general population has clinically silent stroke on brain imaging. These lesions may cause symptoms. This study assessed the prevalence of stroke symptoms in a stroke- and transient ischemic attack (TIA)-free population and the association of symptoms with risk factors indexed by the Framingham Stroke Risk Score. We performed a cross-sectional analysis from a randomly sampled national cohort enrolled from January 25, 2003, through November 30, 2005, with oversampling from the southeastern stroke belt and African American populations. The main outcome measure was stroke symptoms assessed by validated questionnaire. The study included 18 462 (41% African American; 51% female; mean age, 65.8 years) participants who reported no stroke or TIA. The prevalence of stroke symptoms was 5.8% for sudden painless hemibody weakness, 8.5% for sudden hemibody numbness, 4.6% for sudden painless loss of vision in one or both eyes, 3.1% for sudden hemifield visual loss, 2.7% for sudden inability to understand speech, and 3.8% for sudden inability of linguistic expression. The prevalence of 1 or more symptoms was 17.8%. Relative to the first quartile of the Framingham Stroke Risk Score, the adjusted odds ratio for 1 or more stroke symptoms increased from 1.0 (95% confidence interval [CI], 0.90-1.2) in the second quartile to 1.2 (95% CI, 1.1-1.5) and 1.5 (95% CI, 1.3-1.6) in successive quartiles. Symptoms were more prevalent among African American compared with white participants and among those with lower income, lower educational level, and fair to poor perceived health status. The general population without prior diagnosed stroke or TIA has a high prevalence of stroke symptoms. The relationship between symptoms and risk factors suggests that some symptomatic individuals may have had clinically undetected cerebrovascular events and may benefit from aggressive stroke prophylaxis.

  16. Idea and implementation studies of populating TOPO250 component with the data from TOPO10 - generalization of geographic information in the BDG database. (Polish Title: Koncepcja i studium implementacji procesu zasilania komponentu TOPO250 danymi TOPO10 - generalizacja informacji geograficznej w bazie danych BDG )

    NASA Astrophysics Data System (ADS)

    Olszewski, R.; Pillich-Kolipińska, A.; Fiedukowicz, A.

    2013-12-01

    Implementation of INSPIRE Directive in Poland requires not only legal transposition but also development of a number of technological solutions. The one of such tasks, associated with creation of Spatial Information Infrastructure in Poland, is developing a complex model of georeference database. Significant funding for GBDOT project enables development of the national basic topographical database as a multiresolution database (MRDB). Effective implementation of this type of database requires developing procedures for generalization of geographic information (generalization of digital landscape model - DLM), which, treating TOPO10 component as the only source for creation of TOPO250 component, will allow keeping conceptual and classification consistency between those database elements. To carry out this task, the implementation of the system's concept (prepared previously for Head Office of Geodesy and Cartography) is required. Such system is going to execute the generalization process using constrained-based modeling and allows to keep topological relationships between the objects as well as between the object classes. Full implementation of the designed generalization system requires running comprehensive tests which would help with its calibration and parameterization of the generalization procedures (related to the character of generalized area). Parameterization of this process will allow determining the criteria of specific objects selection, simplification algorithms as well as the operation order. Tests with the usage of differentiated, related to the character of the area, generalization process parameters become nowadays the priority issue. Parameters are delivered to the system in the form of XML files, which, with the help of dedicated tool, are generated from the spreadsheet files (XLS) filled in by user. Using XLS file makes entering and modifying the parameters easier. Among the other elements defined by the external parametric files there are

  17. Ontology for cell-based geographic information

    NASA Astrophysics Data System (ADS)

    Zheng, Bin; Huang, Lina; Lu, Xinhai

    2009-10-01

    Inter-operability is a key notion in geographic information science (GIS) for the sharing of geographic information (GI). That requires a seamless translation among different information sources. Ontology is enrolled in GI discovery to settle the semantic conflicts for its natural language appearance and logical hierarchy structure, which are considered to be able to provide better context for both human understanding and machine cognition in describing the location and relationships in the geographic world. However, for the current, most studies on field ontology are deduced from philosophical theme and not applicable for the raster expression in GIS-which is a kind of field-like phenomenon but does not physically coincide to the general concept of philosophical field (mostly comes from the physics concepts). That's why we specifically discuss the cell-based GI ontology in this paper. The discussion starts at the investigation of the physical characteristics of cell-based raster GI. Then, a unified cell-based GI ontology framework for the recognition of the raster objects is introduced, from which a conceptual interface for the connection of the human epistemology and the computer world so called "endurant-occurrant window" is developed for the better raster GI discovery and sharing.

  18. Characterization of the altered gene expression profile in early porcine embryos generated from parthenogenesis and somatic cell chromatin transfer.

    PubMed

    Zhou, Chi; Dobrinsky, John; Tsoi, Stephen; Foxcroft, George R; Dixon, Walter T; Stothard, Paul; Verstegen, John; Dyck, Michael K

    2014-01-01

    The in vitro production of early porcine embryos is of particular scientific and economic interest. In general, embryos produced from in vitro Assisted Reproductive Technologies (ART) manipulations, such as somatic cell chromatin transfer (CT) and parthenogenetic activation (PA), are less developmentally competent than in vivo-derived embryos. The mechanisms underlying the deficiencies of embryos generated from PA and CT have not been completely understood. To characterize the altered genes and gene networks in embryos generated from CT and PA, comparative transcriptomic analyses of in vivo (IVV) expanded blastocysts (XB), IVV hatched blastocyst (HB), PA XB, PA HB, and CT HB were performed using a custom microarray platform enriched for genes expressed during early embryonic development. Differential expressions of 1492 and 103 genes were identified in PA and CT HB, respectively, in comparison with IVV HB. The "eIF2 signalling", "mitochondrial dysfunction", "regulation of eIF4 and p70S6K signalling", "protein ubiquitination", and "mTOR signalling" pathways were down-regulated in PA HB. Dysregulation of notch signalling-associated genes were observed in both PA and CT HB. TP53 was predicted to be activated in both PA and CT HB, as 136 and 23 regulation targets of TP53 showed significant differential expression in PA and CT HB, respectively, in comparison with IVV HB. In addition, dysregulations of several critical pluripotency, trophoblast development, and implantation-associated genes (NANOG, GATA2, KRT8, LGMN, and DPP4) were observed in PA HB during the blastocyst hatching process. The critical genes that were observed to be dysregulated in CT and PA embryos could be indicative of underlying developmental deficiencies of embryos produced from these technologies.

  19. The geographical accessibility of hospitals to the aged: a geographic information systems analysis within Illinois.

    PubMed Central

    Love, D; Lindquist, P

    1995-01-01

    OBJECTIVE. This article uses geographic information systems and their related tools to empirically measure and display the geographic accessibility of the aged population to hospital facilities within Illinois. DATA SOURCES AND STUDY SETTING. Geographic accessibility of Illinois' aged population is measured from each of the state's 10,796 census block groups to the state's 214 hospital facilities. Block group demographic compositions and centroids are obtained from 1990 census files. Hospital coordinates are obtained by the authors. STUDY DESIGN. Of five alternative measures of accessibility considered, empirical estimates are obtained for two: choice set and minimum distance. Access to both general hospitals and the subset having specialized geriatric facilities is measured with special attention to differences in accessibility between the aged within metropolitan statistical areas (MSAs) and those outside MSAs. Cumulative accessibility distributions and their summary statistics provide a basis of comparison among subgroups. DATA COLLECTION AND EXTRACTION. Geographic information systems (GIS) and their related tools are used as a means of efficiently capturing, organizing, storing, and retrieving the required data. Hospitals and census block groups are geocoded to specific locations in the database, and aspatial attributes are assigned to the hospitals and block groups. The GIS database is queried to produce shaded isarithm and point distribution maps that show the location of hospitals relative to surrounding aged populations. CONCLUSION. The vast majority of Illinois' aged population is within close proximity to hospital facilities. Eighty percent (1,147,504 persons) of the aged in Illinois are within 4.8 miles (7.7 km) of a hospital and 11.6 miles (18.7 km) of two hospitals. However, geographic accessibility differences between the aged living in MSAs and those living outside MSAs to hospitals offering geriatric services are substantial; but there is no

  20. Evaluating geographic information systems technology

    USGS Publications Warehouse

    Guptill, Stephen C.

    1989-01-01

    Computerized geographic information systems (GISs) are emerging as the spatial data handling tools of choice for solving complex geographical problems. However, few guidelines exist for assisting potential users in identifying suitable hardware and software. A process to be followed in evaluating the merits of GIS technology is presented. Related standards and guidelines, software functions, hardware components, and benchmarking are discussed. By making users aware of all aspects of adopting GIS technology, they can decide if GIS is an appropriate tool for their application and, if so, which GIS should be used.

  1. Multiple sclerosis: a geographical hypothesis.

    PubMed

    Carlyle, I P

    1997-12-01

    Multiple sclerosis remains a rare neurological disease of unknown aetiology, with a unique distribution, both geographically and historically. Rare in equatorial regions, it becomes increasingly common in higher latitudes; historically, it was first clinically recognized in the early nineteenth century. A hypothesis, based on geographical reasoning, is here proposed: that the disease is the result of a specific vitamin deficiency. Different individuals suffer the deficiency in separate and often unique ways. Evidence to support the hypothesis exists in cultural considerations, in the global distribution of the disease, and in its historical prevalence.

  2. 5 CFR 536.303 - Geographic conversion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Geographic conversion. 536.303 Section... PAY RETENTION Pay Retention § 536.303 Geographic conversion. (a) Geographic conversion at time of... basic pay resulting from this geographic conversion is not a basis for entitlement to pay retention. The...

  3. 5 CFR 536.303 - Geographic conversion.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Geographic conversion. 536.303 Section... PAY RETENTION Pay Retention § 536.303 Geographic conversion. (a) Geographic conversion at time of... basic pay resulting from this geographic conversion is not a basis for entitlement to pay retention. The...

  4. Changes at the National Geographic Society

    ERIC Educational Resources Information Center

    Schwille, Kathleen

    2016-01-01

    For more than 125 years, National Geographic has explored the planet, unlocking its secrets and sharing them with the world. For almost thirty of those years, National Geographic has been committed to K-12 educators and geographic education through its Network of Alliances. As National Geographic begins a new chapter, they remain committed to the…

  5. Plants and geographical names in Croatia.

    PubMed

    Cargonja, Hrvoje; Daković, Branko; Alegro, Antun

    2008-09-01

    The main purpose of this paper is to present some general observations, regularities and insights into a complex relationship between plants and people through symbolic systems like geographical names on the territory of Croatia. The basic sources of data for this research were maps from atlas of Croatia of the scale 1:100000. Five groups of maps or areas were selected in order to represent main Croatian phytogeographic regions. A selection of toponyms from each of the map was made in which the name for a plant in Croatian language was recognized (phytotoponyms). Results showed that of all plant names recognized in geographical names the most represented are trees, and among them birch and oak the most. Furthermore, an attempt was made to explain the presence of the most represented plant species in the phytotoponyms in the light of general phytogeographical and sociocultural differences and similarities of comparing areas. The findings confirm an expectation that the genera of climazonal vegetation of particular area are the most represented among the phytotoponyms. Nevertheless, there are ample examples where representation of a plant name in the names of human environment can only be ascribed to ethno-linguistic and socio-cultural motives. Despite the reductionist character of applied methodology, this research also points out some advantages of this approach for ethnobotanic and ethnolinguistic studies of greater areas of human environment.

  6. Geographical differences in food allergy.

    PubMed

    Bartra, Joan; García-Moral, Alba; Enrique, Ernesto

    2016-06-01

    Food allergy represents a health problem worldwide and leads to life-threatening reactions and even impairs quality of life. Epidemiological data during the past decades is very heterogeneous because of the use of different diagnostic procedures, and most studies have only been performed in specific geographical areas. The aim of this article is to review the available data on the geographical distribution of food allergies at the food source and molecular level and to link food allergy patterns to the aeroallergen influence in each area. Systematic reviews, meta-analysis, studies performed within the EuroPrevall Project and EAACI position papers regarding food allergy were analysed. The prevalence of food allergy sensitization differs between geographical areas, probably as a consequence of differences among populations, their habits and the influence of the cross-reactivity of aeroallergens and other sources of allergens. Geographical differences in food allergy are clearly evident at the allergenic molecular level, which seems to be directly influenced by the aeroallergens of each region and associated with specific clinical patterns.

  7. Educational Geographers and Applied Geography.

    ERIC Educational Resources Information Center

    Frazier, John W.

    1979-01-01

    Describes the development of applied geography programs and restructuring of curricula with an emphasis on new technique and methodology courses, though retaining the liberal arts role. Educational geographers can help the programs to succeed through curriculum analysis, auditing, advising students, and liaison with other geography sources. (CK)

  8. Geographical Concepts in Turkish Lullabys

    ERIC Educational Resources Information Center

    Çifçi, Taner

    2016-01-01

    In this study, a collection of lullabies which have an important place in Turkish culture and which form an important genre in folk literature are examined to find out distribution and presentation of geographical terms in the lullabies in this collection. In the study, 2480 lullabies in Turkish Lullabies which is one of the leading collections in…

  9. Harvesting geographic features from heterogeneous raster maps

    NASA Astrophysics Data System (ADS)

    Chiang, Yao-Yi

    2010-11-01

    Raster maps offer a great deal of geospatial information and are easily accessible compared to other geospatial data. However, harvesting geographic features locked in heterogeneous raster maps to obtain the geospatial information is challenging. This is because of the varying image quality of raster maps (e.g., scanned maps with poor image quality and computer-generated maps with good image quality), the overlapping geographic features in maps, and the typical lack of metadata (e.g., map geocoordinates, map source, and original vector data). Previous work on map processing is typically limited to a specific type of map and often relies on intensive manual work. In contrast, this thesis investigates a general approach that does not rely on any prior knowledge and requires minimal user effort to process heterogeneous raster maps. This approach includes automatic and supervised techniques to process raster maps for separating individual layers of geographic features from the maps and recognizing geographic features in the separated layers (i.e., detecting road intersections, generating and vectorizing road geometry, and recognizing text labels). The automatic technique eliminates user intervention by exploiting common map properties of how road lines and text labels are drawn in raster maps. For example, the road lines are elongated linear objects and the characters are small connected-objects. The supervised technique utilizes labels of road and text areas to handle complex raster maps, or maps with poor image quality, and can process a variety of raster maps with minimal user input. The results show that the general approach can handle raster maps with varying map complexity, color usage, and image quality. By matching extracted road intersections to another geospatial dataset, we can identify the geocoordinates of a raster map and further align the raster map, separated feature layers from the map, and recognized features from the layers with the geospatial

  10. Assesing Geographic Isolation of the Galapagos Islands

    NASA Astrophysics Data System (ADS)

    Orellana, D.; Smith, F.

    2016-06-01

    The Galapagos Archipelago is one of the most important ecological spots in the planet due its unique biodiversity, active geology, and relatively well-preserved ecosystems. These characteristics are strongly based on the geographical isolation of the islands. On the one hand this isolation allowed the evolution processes that gave the islands their international fame and on the other hand it kept them from major human impacts that affected the vast majority of the Earth's surface. Galapagos' geographical isolation is therefore of mayor value, but it is rapidly diminishing due to the increase of marine and air transportation among islands and with the rest of the world. This increased accessibility implies enhanced risks for the ecological dynamics on the archipelago (e.g. increased risk of biological invasions, uncontrolled tourism growth, more water and energy consumption). Here, we introduce a general accessibility model to assess geographical isolation of the Galapagos Islands. The model aims to characterize accessibility in terms of human mobility by evaluating travel time to each point of the archipelago using all available transportation modalities. Using a multi criteria cost surface for marine and land areas, we estimated travel time for each surface unit using the fastest route and mode of transportation available while considering several friction factors such as surface type, slope, infrastructure, transfer points, legal restrictions, and physical barriers. We created maps to evaluate the isolation of different islands and places, highlighting the potential risks for several habitats and ecosystems. The model can be used for research and decision-making regarding island conservation, such as estimating spreading paths for invasive species, informing decisions on tourism management, and monitoring isolation changes of sensitive ecosystems.

  11. Geographic Information System Data Analysis

    NASA Technical Reports Server (NTRS)

    Billings, Chad; Casad, Christopher; Floriano, Luis G.; Hill, Tracie; Johnson, Rashida K.; Locklear, J. Mark; Penn, Stephen; Rhoulac, Tori; Shay, Adam H.; Taylor, Antone; hide

    1995-01-01

    Data was collected in order to further NASA Langley Research Center's Geographic Information System(GIS). Information on LaRC's communication, electrical, and facility configurations was collected. Existing data was corrected through verification, resulting in more accurate databases. In addition, Global Positioning System(GPS) points were used in order to accurately impose buildings on digitized images. Overall, this project will help the Imaging and CADD Technology Team (ICTT) prove GIS to be a valuable resource for LaRC.

  12. Geographical Applications of Remote Sensing

    SciTech Connect

    Weng, Qihao; Zhou, Yuyu; Quattrochi, Dale

    2013-02-28

    Data and Information derived through Earth observation technology have been extensively used in geographic studies, such as in the areas of natural and human environments, resources, land use and land cover, human-environment interactions, and socioeconomic issues. Land-use and land-cover change (LULCC), affecting biodiversity, climate change, watershed hydrology, and other surface processes, is one of the most important research topics in geography.

  13. Geographic names of the Antarctic

    USGS Publications Warehouse

    ,; ,; ,; ,; Alberts, Fred G.

    1995-01-01

    This gazetteer contains 12,710 names approved by the United States Board on Geographic Names and the Secretary of the Interior for features in Antarctica and the area extending northward to the Antarctic Convergence. Included in this geographic area, the Antarctic region, are the off-lying South Shetland Islands, the South Orkney Islands, the South Sandwich Islands, South Georgia, Bouvetøya, Heard Island, and the Balleny Islands. These names have been approved for use by U.S. Government agencies. Their use by the Antarctic specialist and the public is highly recommended for the sake of accuracy and uniformity. This publication, which supersedes previous Board gazetteers or lists for the area, contains names approved as recently as December 1994. The basic name coverage of this gazetteer corresponds to that of maps at the scale of 1:250,000 or larger for coastal Antarctica, the off-lying islands, and isolated mountains and ranges of the continent. Much of the interior of Antarctica is a featureless ice plateau. That area has been mapped at a smaller scale and is nearly devoid of toponyms. All of the names are for natural features, such as mountains, glaciers, peninsulas, capes, bays, islands, and subglacial entities. The names of scientific stations have not been listed alphabetically, but they may appear in the texts of some decisions. For the names of submarine features, reference should be made to the Gazetteer of Undersea Features, 4th edition, U.S. Board on Geographic Names, 1990.

  14. Geographic Mobility of Postsecondary Occupational Education Graduates. Phase II.

    ERIC Educational Resources Information Center

    Winter, Gene M.; Fadale, LaVerna M.

    This report of the second phase of a study of the geographic mobility patterns of postsecondary occupational education graduates in New York State provides a further examination of reasons for the mobility of program completers, verifies the general magnitude of the identified mobility trends, and examines the occupational status of program…

  15. Campus-Based Geographic Learning: A Field Oriented Teaching Scenario

    ERIC Educational Resources Information Center

    Jennings, Steven A.; Huber, Thomas P.

    2003-01-01

    The use of field classes and the need for university master planning are presented as a way to enhance learning. This field-oriented, goal-oriented approach to learning is proposed as a general model for university-level geographic education. This approach is presented for physical geography classes, but could also be applied to other subdivisions…

  16. Using Visual Basic to Teach Programming for Geographers.

    ERIC Educational Resources Information Center

    Slocum, Terry A.; Yoder, Stephen C.

    1996-01-01

    Outlines reasons why computer programming should be taught to geographers. These include experience using macro (scripting) languages and sophisticated visualization software, and developing a deeper understanding of general hardware and software capabilities. Discusses the distinct advantages and few disadvantages of the programming language…

  17. Practical applications of the geographic coordinate data base in Arkansas

    Treesearch

    Mickie Warwick; Don C. Bragg

    2005-01-01

    Though not intended for these applications, the General Land Office (GLO) survey notes are a primary source of historical, ecological, and cultural information, making it imperative that their spatial coordinates be as reliable as possible. The Geographic Coordinate Data Base (GCDB) is a statistically-based coordinate fitting program that uses the GLO notes and other...

  18. Geographic variation within the military health system.

    PubMed

    Kimsey, Linda; Olaiya, Samuel; Smith, Chad; Hoburg, Andrew; Lipsitz, Stuart R; Koehlmoos, Tracey; Nguyen, Louis L; Weissman, Joel S

    2017-04-13

    This study seeks to quantify variation in healthcare utilization and per capita costs using system-defined geographic regions based on enrollee residence within the Military Health System (MHS). Data for fiscal years 2007 - 2010 were obtained from the Military Health System under a data sharing agreement with the Defense Health Agency (DHA). DHA manages all aspects of the Department of Defense Military Health System, including TRICARE. Adjusted rates were calculated for per capita costs and for two procedures with high interest to the MHS- back surgery and Cesarean sections for TRICARE Prime and Plus enrollees. Coefficients of variation (CoV) and interquartile ranges (IQR) were calculated and analyzed using residence catchment area as the geographic unit. Catchment areas anchored by a Military Treatment Facility (MTF) were compared to catchment areas not anchored by a MTF. Variation, as measured by CoV, was 0.37 for back surgery and 0.13 for C-sections in FY 2010- comparable to rates documented in other healthcare systems. The 2010 CoV (and average cost) for per capita costs was 0.26 ($3,479.51). Procedure rates were generally lower and CoVs higher in regions anchored by a MTF compared with regions not anchored by a MTF, based on both system-wide comparisons and comparisons of neighboring areas. In spite of its centrally managed system and relatively healthy beneficiaries with very robust health benefits, the MHS is not immune to unexplained variation in utilization and cost of healthcare.

  19. Integrating geographically isolated wetlands into land ...

    EPA Pesticide Factsheets

    Wetlands across the globe provide extensive ecosystem services. However, many wetlands – especially those surrounded by uplands, often referred to as geographically isolated wetlands (GIWs) – remain poorly protected. Protection and restoration of wetlands frequently requires information on their hydrologic connectivity to other surface waters, and their cumulative watershed-scale effects. The integration of measurements and models can supply this information. However, the types of measurements and models that should be integrated are dependent on management questions and information compatibility. We summarize the importance of GIWs in watersheds and discuss what wetland connectivity means in both science and management contexts. We then describe the latest tools available to quantify GIW connectivity and explore crucial next steps to enhancing and integrating such tools. These advancements will ensure that appropriate tools are used in GIW decision making and maintaining the important ecosystem services that these wetlands support. In a nutshell: Wetlands in general receive insufficient protection and this is particularly true for geographically isolated wetlands (GIWs), which are completely surrounded by upland areas GIWs have recently gained policy attention because they provide important ecosystem services, but like most wetlands, their loss and degradation continues Knowledge of the hydrologic connections of GIWs to downstream waters is necessary for th

  20. 33 CFR 165.8 - Geographic coordinates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 1983 (NAD 83), unless such geographic coordinates are expressly labeled NAD 83. Geographic coordinates without the NAD 83 reference may be plotted on maps or charts referenced to NAD 83 only after application...

  1. Research and Research Methods in Geographical Education.

    ERIC Educational Resources Information Center

    Graves, Norman J., Ed.

    This collection of papers examines research methods in geographical education in nine countries. "Research Methods in the History of Geographical Education" (William Marsden, the United Kingdom) examines the methods used and some of the research undertaken in the history of geographical education. "Research Methods in Investigating…

  2. Geographical variation in neonatal phenotype

    PubMed Central

    Leary, Sam; Fall, Caroline; Osmond, Clive; Lovel, Hermione; Campbell, Doris; Eriksson, Johan; Forrester, Terrence; Godfrey, Keith; Hill, Jacqui; Jie, Mi; Law, Catherine; Newby, Rachel; Robinson, Sian; Yajnik, Chittaranjan

    2009-01-01

    Background Recent studies have shown associations between size and body proportions at birth and health outcomes throughout the life cycle, but there are few data on how neonatal phenotype varies in different populations around the world. Methods Data from the UK, Finland, India, Sri Lanka, China, DR Congo, Nigeria and Jamaica (N=22 067) were used to characterise geographical differences in phenotype in singleton, liveborn newborns. Measurements included birthweight, placental weight, length, head, chest, abdominal and arm circumferences and skinfolds. Results Neonates in Europe were the largest, followed by Jamaica, East Asia (China), then Africa and South Asia. Birthweight varied widely (mean values 2730g to 3570g), but in contrast, head circumference was similar in all except China (markedly smaller). The main difference in body proportions between populations was the head to length ratio, with small heads relative to length in China and large heads relative to length in South Asia and Africa. Conclusions These marked geographical differences in neonatal phenotype need to be considered when investigating determinants of fetal growth, and optimal phenotype for short-term and long-term outcomes. PMID:16929412

  3. Geographic profiling and animal foraging.

    PubMed

    Le Comber, Steven C; Nicholls, Barry; Rossmo, D Kim; Racey, Paul A

    2006-05-21

    Geographic profiling was originally developed as a statistical tool for use in criminal cases, particularly those involving serial killers and rapists. It is designed to help police forces prioritize lists of suspects by using the location of crime scenes to identify the areas in which the criminal is most likely to live. Two important concepts are the buffer zone (criminals are less likely to commit crimes in the immediate vicinity of their home) and distance decay (criminals commit fewer crimes as the distance from their home increases). In this study, we show how the techniques of geographic profiling may be applied to animal data, using as an example foraging patterns in two sympatric colonies of pipistrelle bats, Pipistrellus pipistrellus and P. pygmaeus, in the northeast of Scotland. We show that if model variables are fitted to known roost locations, these variables may be used as numerical descriptors of foraging patterns. We go on to show that these variables can be used to differentiate patterns of foraging in these two species.

  4. 24 CFR 599.103 - Geographic and population requirements for a nominated area.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 3 2013-04-01 2013-04-01 false Geographic and population... Requirements for Nomination of Renewal Communities § 599.103 Geographic and population requirements for a... part. (b) Population requirements—(1) In general. Except as provided in paragraph (b)(2) of this...

  5. 24 CFR 599.103 - Geographic and population requirements for a nominated area.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false Geographic and population... Requirements for Nomination of Renewal Communities § 599.103 Geographic and population requirements for a... part. (b) Population requirements—(1) In general. Except as provided in paragraph (b)(2) of this...

  6. 24 CFR 599.103 - Geographic and population requirements for a nominated area.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 3 2012-04-01 2012-04-01 false Geographic and population... Requirements for Nomination of Renewal Communities § 599.103 Geographic and population requirements for a... part. (b) Population requirements—(1) In general. Except as provided in paragraph (b)(2) of this...

  7. 24 CFR 599.103 - Geographic and population requirements for a nominated area.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 3 2014-04-01 2013-04-01 true Geographic and population... Requirements for Nomination of Renewal Communities § 599.103 Geographic and population requirements for a... part. (b) Population requirements—(1) In general. Except as provided in paragraph (b)(2) of this...

  8. 24 CFR 599.103 - Geographic and population requirements for a nominated area.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 3 2011-04-01 2010-04-01 true Geographic and population... Requirements for Nomination of Renewal Communities § 599.103 Geographic and population requirements for a... part. (b) Population requirements—(1) In general. Except as provided in paragraph (b)(2) of this...

  9. Brief Report: Diminishing Geographic Variability in Autism Spectrum Disorders over Time?

    ERIC Educational Resources Information Center

    Hoffman, Kate; Vieira, Veronica M.; Daniels, Julie L.

    2014-01-01

    We investigated differences in the geographic distribution of autism spectrum disorders (ASD) over time in central North Carolina with data from the Autism and Developmental Disabilities Monitoring Network. Using generalized additive models and geographic information systems we produced maps of ASD risk in 2002-2004 and 2006-2008. Overall the risk…

  10. Analysis of impact of geographic characteristics on suicide rate and visualization of result with Geographic Information System.

    PubMed

    Oka, Mayumi; Kubota, Takafumi; Tsubaki, Hiroe; Yamauchi, Keita

    2015-06-01

    The aim of our study was to understand the geographic characteristics of Japanese communities and the impact of these characteristics on suicide rates. We calculated the standardized mortality ratio from suicide statistics of 3318 municipalities from 1972 to 2002. Correlation analysis, multi-regression analysis and generalized additive model were used to find the relation between topographic and climatic variables and suicide rate. We visualized the relation between geographic characteristics and suicide rate on the map of Wakayama Prefecture, using the Geographic Information System. Our study showed that the geographic characteristics of each community are related with its suicide rate. The strongest factor among the geographic characteristics to increase the suicide rate was the slope of the habitable land. It is necessary to take the characteristics of each community into consideration when we work out measures of suicide prevention. Visualization of the findings on the local map should be helpful to promote understanding of problems and to share the information among various parties in charge of suicide prevention. © 2014 The Authors. Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology.

  11. Investigation of Error Patterns in Geographical Databases

    NASA Technical Reports Server (NTRS)

    Dryer, David; Jacobs, Derya A.; Karayaz, Gamze; Gronbech, Chris; Jones, Denise R. (Technical Monitor)

    2002-01-01

    The objective of the research conducted in this project is to develop a methodology to investigate the accuracy of Airport Safety Modeling Data (ASMD) using statistical, visualization, and Artificial Neural Network (ANN) techniques. Such a methodology can contribute to answering the following research questions: Over a representative sampling of ASMD databases, can statistical error analysis techniques be accurately learned and replicated by ANN modeling techniques? This representative ASMD sample should include numerous airports and a variety of terrain characterizations. Is it possible to identify and automate the recognition of patterns of error related to geographical features? Do such patterns of error relate to specific geographical features, such as elevation or terrain slope? Is it possible to combine the errors in small regions into an error prediction for a larger region? What are the data density reduction implications of this work? ASMD may be used as the source of terrain data for a synthetic visual system to be used in the cockpit of aircraft when visual reference to ground features is not possible during conditions of marginal weather or reduced visibility. In this research, United States Geologic Survey (USGS) digital elevation model (DEM) data has been selected as the benchmark. Artificial Neural Networks (ANNS) have been used and tested as alternate methods in place of the statistical methods in similar problems. They often perform better in pattern recognition, prediction and classification and categorization problems. Many studies show that when the data is complex and noisy, the accuracy of ANN models is generally higher than those of comparable traditional methods.

  12. Fundamental procedures of geographic information analysis

    NASA Technical Reports Server (NTRS)

    Berry, J. K.; Tomlin, C. D.

    1981-01-01

    Analytical procedures common to most computer-oriented geographic information systems are composed of fundamental map processing operations. A conceptual framework for such procedures is developed and basic operations common to a broad range of applications are described. Among the major classes of primitive operations identified are those associated with: reclassifying map categories as a function of the initial classification, the shape, the position, or the size of the spatial configuration associated with each category; overlaying maps on a point-by-point, a category-wide, or a map-wide basis; measuring distance; establishing visual or optimal path connectivity; and characterizing cartographic neighborhoods based on the thematic or spatial attributes of the data values within each neighborhood. By organizing such operations in a coherent manner, the basis for a generalized cartographic modeling structure can be developed which accommodates a variety of needs in a common, flexible and intuitive manner. The use of each is limited only by the general thematic and spatial nature of the data to which it is applied.

  13. Geographic distance affects dispersal of the patchy distributed greater long-tailed hamster (Tscherskia triton).

    PubMed

    Xue, Huiliang; Zhong, Min; Xu, Jinhui; Xu, Laixiang

    2014-01-01

    Dispersal is a fundamental process in ecology influencing the genetic structure and the viability of populations. Understanding how variable factors influence the dispersal of the population is becoming an important question in animal ecology. To date, geographic distance and geographic barriers are often considered as main factors impacting dispersal, but their effects are variable depending on different conditions. In general, geographic barriers affect more significantly than geographic distance on dispersal. In rapidly expanding populations, however, geographic barriers have less effect on dispersal than geographic distance. The effects of both geographic distance and geographic barriers in low-density populations with patchy distributions are poorly understood. By using a panel of 10 microsatellite loci we investigated the genetic structure of three patchy-distributed populations of the Greater long-tailed hamster (Tscherskia triton) from Raoyang, Guan and Shunyi counties of the North China Plain. The results showed that (i) high genetic diversity and differentiation exist in three geographic populations with patchy distributions; (ii) gene flow occurs among these three populations with physical barriers of Beijing city and Hutuo River, which potentially restricted the dispersal of the animal; (iii) the gene flow is negatively correlated with the geographic distance, while the genetic distance shows the positive correlation. Our results suggest that the effect of the physical barriers is conditional-dependent, including barrier capacity or individual potentially dispersal ability. Geographic distance also acts as an important factor affecting dispersal for the patchy distributed geographic populations. So, gene flow is effective, even at relatively long distances, in balancing the effect of geographic barrier in this study.

  14. The Oklahoma Geographic Information Retrieval System

    NASA Technical Reports Server (NTRS)

    Blanchard, W. A.

    1982-01-01

    The Oklahoma Geographic Information Retrieval System (OGIRS) is a highly interactive data entry, storage, manipulation, and display software system for use with geographically referenced data. Although originally developed for a project concerned with coal strip mine reclamation, OGIRS is capable of handling any geographically referenced data for a variety of natural resource management applications. A special effort has been made to integrate remotely sensed data into the information system. The timeliness and synoptic coverage of satellite data are particularly useful attributes for inclusion into the geographic information system.

  15. Representing and Acquiring Geographic Knowledge.

    DTIC Science & Technology

    1984-01-01

    which is allowed if v is a kowledge bound of REG. e3. The real vertices of a clump map into the boundary of the corresponding object so * , 21...example, *What is the diameter of the pond?" can be answered, but the answer will, in general, be a range power -bound, upper-bound]. If the clump for...cases of others. They are included separately, because their procedures are either faster or more powerful than the general procedure. I will not

  16. 25 CFR 571.10 - Geographical location.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 25 Indians 2 2012-04-01 2012-04-01 false Geographical location. 571.10 Section 571.10 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR COMPLIANCE AND ENFORCEMENT PROVISIONS MONITORING AND INVESTIGATIONS Subpoenas and Depositions § 571.10 Geographical location. The attendance of...

  17. 25 CFR 571.10 - Geographical location.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 2 2011-04-01 2011-04-01 false Geographical location. 571.10 Section 571.10 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR COMPLIANCE AND ENFORCEMENT PROVISIONS MONITORING AND INVESTIGATIONS Subpoenas and Depositions § 571.10 Geographical location. The attendance of...

  18. 25 CFR 571.10 - Geographical location.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 2 2014-04-01 2014-04-01 false Geographical location. 571.10 Section 571.10 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR COMPLIANCE AND ENFORCEMENT PROVISIONS MONITORING AND INVESTIGATIONS Subpoenas and Depositions § 571.10 Geographical location. The attendance of...

  19. 25 CFR 571.10 - Geographical location.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 2 2013-04-01 2013-04-01 false Geographical location. 571.10 Section 571.10 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR COMPLIANCE AND ENFORCEMENT PROVISIONS MONITORING AND INVESTIGATIONS Subpoenas and Depositions § 571.10 Geographical location. The attendance of...

  20. The evolution of cooperation on geographical networks

    NASA Astrophysics Data System (ADS)

    Li, Yixiao; Wang, Yi; Sheng, Jichuan

    2017-11-01

    We study evolutionary public goods game on geographical networks, i.e., complex networks which are located on a geographical plane. The geographical feature effects in two ways: In one way, the geographically-induced network structure influences the overall evolutionary dynamics, and, in the other way, the geographical length of an edge influences the cost when the two players at the two ends interact. For the latter effect, we design a new cost function of cooperators, which simply assumes that the longer the distance between two players, the higher cost the cooperator(s) of them have to pay. In this study, network substrates are generated by a previous spatial network model with a cost-benefit parameter controlling the network topology. Our simulations show that the greatest promotion of cooperation is achieved in the intermediate regime of the parameter, in which empirical estimates of various railway networks fall. Further, we investigate how the distribution of edges' geographical costs influences the evolutionary dynamics and consider three patterns of the distribution: an approximately-equal distribution, a diverse distribution, and a polarized distribution. For normal geographical networks which are generated using intermediate values of the cost-benefit parameter, a diverse distribution hinders the evolution of cooperation, whereas a polarized distribution lowers the threshold value of the amplification factor for cooperation in public goods game. These results are helpful for understanding the evolution of cooperation on real-world geographical networks.

  1. 33 CFR 166.103 - Geographic coordinates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... charts whose referenced horizontal datum is the North American Datum of 1983 (NAD 83), unless such geographic coordinates are expressly labeled NAD 83. Geographic coordinates without the NAD 83 reference may be plotted on maps or charts referenced to NAD 83 only after application of the appropriate...

  2. Suggested Geographic Information Literacy for K-12

    ERIC Educational Resources Information Center

    Miller, Jason; Keller, C. Peter; Yore, Larry D.

    2005-01-01

    Geographic information literacy (GIL) is defined as the possession of concepts, abilities and habits of mind that allow an individual to understand and use geographic information properly. This paper reports the results of an online survey undertaken to get expert input into specifying the concepts and abilities associated with GIL that should be…

  3. 25 CFR 571.10 - Geographical location.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 2 2010-04-01 2010-04-01 false Geographical location. 571.10 Section 571.10 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR COMPLIANCE AND ENFORCEMENT PROVISIONS MONITORING AND INVESTIGATIONS Subpoenas and Depositions § 571.10 Geographical location. The attendance of...

  4. Gene genealogies in geographically structured populations

    Treesearch

    Bryan K. Epperson

    1999-01-01

    Population genetics theory has dealt only with the spatial or geographic pattern of degrees of relatedness or genetic similarity separately for each point in time. However, a frequent goal of experimental studies is to infer migration patterns that occurred in the past or over extended periods of time. To fully understand how a present geographic pattern of genetic...

  5. Cartographic services contract...for everything geographic

    USGS Publications Warehouse

    ,

    2003-01-01

    The U.S. Geological Survey's (USGS) Cartographic Services Contract (CSC) is used to award work for photogrammetric and mapping services under the umbrella of Architect-Engineer (A&E) contracting. The A&E contract is broad in scope and can accommodate any activity related to standard, nonstandard, graphic, and digital cartographic products. Services provided may include, but are not limited to, photogrammetric mapping and aerotriangulation; orthophotography; thematic mapping (for example, land characterization); analog and digital imagery applications; geographic information systems development; surveying and control acquisition, including ground-based and airborne Global Positioning System; analog and digital image manipulation, analysis, and interpretation; raster and vector map digitizing; data manipulations (for example, transformations, conversions, generalization, integration, and conflation); primary and ancillary data acquisition (for example, aerial photography, satellite imagery, multispectral, multitemporal, and hyperspectral data); image scanning and processing; metadata production, revision, and creation; and production or revision of standard USGS products defined by formal and informal specification and standards, such as those for digital line graphs, digital elevation models, digital orthophoto quadrangles, and digital raster graphics.

  6. Geographic differences in heart failure trials.

    PubMed

    Ferreira, João Pedro; Girerd, Nicolas; Rossignol, Patrick; Zannad, Faiez

    2015-09-01

    Randomized controlled trials (RCTs) are essential to develop advances in heart failure (HF). The need for increasing numbers of patients (without substantial cost increase) and generalization of results led to the disappearance of international boundaries in large RCTs. The significant geographic differences in patients' characteristics, outcomes, and, most importantly, treatment effect observed in HF trials have recently been highlighted. Whether the observed regional discrepancies in HF trials are due to trial-specific issues, patient heterogeneity, structural differences in countries, or a complex interaction between factors are the questions we propose to debate in this review. To do so, we will analyse and review data from HF trials conducted in different world regions, from heart failure with preserved ejection fraction (HF-PEF), heart failure with reduced ejection fraction (HF-REF), and acute heart failure (AHF). Finally, we will suggest objective and actionable measures in order to mitigate regional discrepancies in future trials, particularly in HF-PEF where prognostic modifying treatments are urgently needed and in which trials are more prone to selection bias, due to a larger patient heterogeneity. © 2015 The Authors European Journal of Heart Failure © 2015 European Society of Cardiology.

  7. The Effect of Geographic Units of Analysis on Measuring Geographic Variation in Medical Services Utilization.

    PubMed

    Kim, Agnus M; Park, Jong Heon; Kang, Sungchan; Hwang, Kyosang; Lee, Taesik; Kim, Yoon

    2016-07-01

    We aimed to evaluate the effect of geographic units of analysis on measuring geographic variation in medical services utilization. For this purpose, we compared geographic variations in the rates of eight major procedures in administrative units (districts) and new areal units organized based on the actual health care use of the population in Korea. To compare geographic variation in geographic units of analysis, we calculated the age-sex standardized rates of eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee-replacement surgery, caesarean section, hysterectomy, computed tomography scan, and magnetic resonance imaging scan) from the National Health Insurance database in Korea for the 2013 period. Using the coefficient of variation, the extremal quotient, and the systematic component of variation, we measured geographic variation for these eight procedures in districts and new areal units. Compared with districts, new areal units showed a reduction in geographic variation. Extremal quotients and inter-decile ratios for the eight procedures were lower in new areal units. While the coefficient of variation was lower for most procedures in new areal units, the pattern of change of the systematic component of variation between districts and new areal units differed among procedures. Geographic variation in medical service utilization could vary according to the geographic unit of analysis. To determine how geographic characteristics such as population size and number of geographic units affect geographic variation, further studies are needed.

  8. GEOGRAPHIC ATROPHY: Semantic Considerations and Literature Review.

    PubMed

    Schmitz-Valckenberg, Steffen; Sadda, Srinivas; Staurenghi, Giovanni; Chew, Emily Y; Fleckenstein, Monika; Holz, Frank G

    2016-12-01

    There is a lack of agreement regarding the types of lesions and clinical conditions that should be included in the term "geographic atrophy." Varied and conflicting views prevail throughout the literature and are currently used by retinal experts and other health care professionals. We reviewed the nominal definition of the term "geographic atrophy" and conducted a search of the ophthalmologic literature focusing on preceding terminologies and the first citations of the term "geographic atrophy" secondary to age-related macular degeneration. According to the nominal definition, the term "geography" stands for a detailed description of the surface features of a specific region, indicating its relative position. However, it does not necessarily imply that the borders of the region must be sharply demarcated or related to any anatomical structures. The term "geographical areas of atrophy" was initially cited in the 1960s in the ophthalmologic literature in the context of uveitic eye disease and shortly thereafter also for the description of variants of "senile macular degeneration." However, no direct explanation could be found in the literature as to why the terms "geographical" and "geographic" were chosen. Presumably the terms were used as the atrophic regions resembled the map of a continent or well-defined country borders on thematic geographical maps. With the evolution of the terminology, the commonly used adjunct "of the retinal pigment epithelium" was frequently omitted and solely the term "geographic atrophy" prevailed for the nonexudative late-stage of age-related macular degeneration itself. Along with the quantification of atrophic areas, based on different imaging modalities and the use of both manual and semiautomated approaches, various and inconsistent definitions for the minimal lesion diameter or size of atrophic lesions have also emerged. Reconsideration of the application of the term "geographic atrophy" in the context of age-related macular

  9. Hosts and geographic distribution of Arceuthobium oxycedri

    Treesearch

    W. M. Ciesla; B. W. Geils; R. P. Adams

    2002-01-01

    Data on hosts and geographic distribution of the juniper dwarf mistletoe, Arceuthobium oxycedri, are updated in light of changes in host nomenclature, political geography, and interpretation of reports and labels. Seventeen species of Juniperus, 3 Chamaecyparis, 5 Cupressus, and 1

  10. Geographic Education--Where Have We Failed?

    ERIC Educational Resources Information Center

    Gritzner, Charles F.

    1981-01-01

    Discusses geography's rather low status and relatively poor public image in the United States and some of the consequences. Among the world's educated industrial nations, the United States ranks among the least literate in a geographical sense. (RM)

  11. The Geographic Distribution of Physicians Revisited

    PubMed Central

    Rosenthal, Meredith B; Zaslavsky, Alan; Newhouse, Joseph P

    2005-01-01

    Context While there is debate over whether the U.S. is training too many physicians, many seem to agree that physicians are geographically maldistributed, with too few in rural areas. Objective Official definitions of shortage areas assume the market for physician services is based on county boundaries. We wished to ascertain how the picture of a possible shortage changes using alternative measures of geographic access. We measure geographic access by the number of full-time equivalent physicians serving a community divided by the expected number of patients (possibly both from within the community and outside) receiving care from those physicians. Moreover, we wished to determine how the geographic distribution of physicians had changed since previous studies, in light of the large increase in physician numbers. Design Cross-sectional data analyses of alternative measures of geographic access to physicians in 23 states with low physician–population ratios. Results Between 1979 and 1999, the number of physicians doubled in the sample states. Although most specialties experienced greater diffusion everywhere, smaller specialties had not yet diffused to the smallest towns. Multiple measures of geographic access, including physician-to-population ratios, average distance traveled to the nearest physician, and projected average caseload per physician, confirm that residents of metropolitan areas have better geographic access to physicians. Physician-to-population ratios exhibit the largest degree of geographic disparity, but ratios in rural counties adjacent to metropolitan areas are smaller than in those not adjacent to metropolitan areas. Distance-traveled and caseload models that allow patients to cross county lines show less disparity and indicate that residents of isolated rural counties have less access than those living in counties adjacent to metropolitan areas. Conclusion Geographic access to physicians has continued to improve over the past two decades

  12. Remote sensing and geographically based information systems

    NASA Technical Reports Server (NTRS)

    Cicone, R. C.

    1977-01-01

    A structure is proposed for a geographically-oriented computer-based information system applicable to the analysis of remote sensing digital data. The structure, intended to answer a wide variety of user needs, would permit multiple views of the data, provide independent management of data security, quality and integrity, and rely on automatic data filing. Problems in geographically-oriented data systems, including those related to line encoding and cell encoding, are considered.

  13. Geographic variation in speed of seed germination in central Oregon ponderosa pine (Pinus ponderosa Dougl. ex Laws.).

    Treesearch

    John C. Weber; Frank C. Sorensen

    1992-01-01

    Variation in speed of seed germination was investigated among ponderosa pine trees representing 225 locations in central Oregon. Results suggested that at least some of the geographic variation is related to the severity of summer drought. In general, germination speed was greater in locations with shod, drought-limited growing seasons. Levels of geographic variation...

  14. Geographic differences in perioperative opioid administration in children

    PubMed Central

    Rabbitts, Jennifer A.; Groenewald, Cornelius B.; Räsänen, Jukka

    2012-01-01

    Objectives To investigate whether geographic differences exist in perioperative opioid administration to children. Aim To investigate whether perioperative fentanyl use for cleft lip and palate surgery varies between children of three different geographic regions. Background Differences have been found in perioperative opioid administration to children of differing ethnicity in the U.S.A. Whether similar differences exist in perioperative opioid administration to children residing in different geographic regions is unknown. Methods/materials We retrospectively reviewed the medical records of ASA I children who underwent surgery under standardized general anesthesia between January 2010 and April 2011 during SMILE Network International mission trips to Africa, India and Central and South America. Perioperative administration of fentanyl was compared between these three locations. Results We analyzed data from 79 children who underwent surgery in Africa, 76 in India and 153 in Central and South America. Children in Central and South America were given less than 50% of the intraoperative amount of fentanyl (2.0 ± 1.2 mcg/kg) administered to children in Africa (4.1 ± 2.4 mcg/kg; p<0.001) and children in India (4.3 ± 2.2 mcg/kg; p < 0.001). Postoperatively, fentanyl was administered in equivalent doses to all groups. Conclusions Children in Central and South America received less opioid intraoperatively than African and Indian children, under standardized anesthesia for cleft surgeries. Further research is necessary to elucidate the mechanisms underlying these group differences. PMID:22324378

  15. 3. Historic American Buildings Survey Photocopy, National Geographic Society Photograph, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Historic American Buildings Survey Photocopy, National Geographic Society Photograph, 1971 Courtesy, National Geographic Society LIBRARY, 1971 - Townsend House, 2121 Massachusetts Avenue Northwest, Washington, District of Columbia, DC

  16. Introductory comments on the USGS geographic applications program

    NASA Technical Reports Server (NTRS)

    Gerlach, A. C.

    1970-01-01

    The third phase of remote sensing technologies and potentials applied to the operations of the U.S. Geological Survey is introduced. Remote sensing data with multidisciplinary spatial data from traditional sources is combined with geographic theory and techniques of environmental modeling. These combined imputs are subject to four sequential activities that involve: (1) thermatic mapping of land use and environmental factors; (2) the dynamics of change detection; (3) environmental surveillance to identify sudden changes and general trends; and (4) preparation of statistical model and analytical reports. Geography program functions, products, clients, and goals are presented in graphical form, along with aircraft photo missions, geography test sites, and FY-70.

  17. The Value of Open Geographical Data - The Danish Case

    NASA Astrophysics Data System (ADS)

    Colding, T. S.; Folner, M.; Krarup, S.; Kongsbak, J.

    2013-12-01

    Good basic data for everyone is part of the common public-sector digitization strategy for 2011 to 2015. The vision is that basic data is to be the high-quality common foundation for public sector administration; efficiently updated at one place, and used by everyone - including the private sector. Open basic data will benefit public-sector efficiency as well as innovation and value creation by Danish society in general. With basic data as a new digital raw material, commercial products can be developed and public information and services can be improved, providing for greater insight and stronger democracy. On the first of January 2013 Denmark released this digital raw material. As a general rule, all basic data is to be made freely available to all public authorities, private businesses and individuals. This makes basic data a common digital resource, which can be exploited freely for commercial as well as non-commercial purposes. A positive business case contributed in convincing Danish politicians to approve the basic data program. Once the initiatives have been fully implemented, the revenues for society are expected to be approx. DKK 800 million annually. Private-sector revenues will be up to DKK half a billion annually, and it is expected that e.g. the real estate, insurance, financial, and telecom sectors, as well as GPS (sat-nav) manufacturers, public companies and entrepreneurs will be among those to benefit hugely from the initiatives. The financial gain for the private sector of open geographical data alone is expected to be approx. 100 million DKK annually. As part of the Basic data program The Danish Geodata Agency (Ministry of the Environment) gave free access to all topographic data, cadastral maps and Digital Elevation Model on Jan. 1st, 2013. The Danish Geodata Agency has decided to measure the effect of the open geographic data in the public sector (efficiency) and in the private sector (growth). The effect will be measured by using reference

  18. Personality Homophily and Geographic Distance in Facebook.

    PubMed

    Noë, Nyala; Whitaker, Roger M; Allen, Stuart M

    2018-05-24

    Personality homophily remains an understudied aspect of social networks, with the traditional focus concerning sociodemographic variables as the basis for assortativity, rather than psychological dispositions. We consider the effect of personality homophily on one of the biggest constraints to human social networks: geographic distance. We use the Big five model of personality to make predictions for each of the five facets: Openness to experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism. Using a network of 313,669 Facebook users, we investigate the difference in geographic distance between homophilous pairs, in which both users scored similarly on a particular facet, and mixed pairs. In accordance with our hypotheses, we find that pairs of open and conscientious users are geographically further apart than mixed pairs. Pairs of extraverts, on the other hand, tend to be geographically closer together. We find mixed results for the Neuroticism facet, and no significant effects for the Agreeableness facet. The results are discussed in the context of personality homophily and the impact of geographic distance on social connections.

  19. Money circulation networks reveal emerging geographical communities

    NASA Astrophysics Data System (ADS)

    Brockmann, D.; Theis, F.; David, V.

    2008-03-01

    Geographical communities and their boundaries are key determinants of various spatially extended dynamical phenomena. Examples are migration dynamics of species, the spread of infectious diseases, bioinvasive processes, and the spatial evolution of language. We address the question to what extend multiscale human transportation networks encode geographical community structures, how they differ from geopolitical classifications, whether they are spatially coherent, and analyse their structure as a function of length scale. Our analysis is based on a proxy network for human transportation obtained from the geographic circulation of more than 10 million dollar bills in the United States recorded at the bill tracking website www.wheresgeorge.com. The data extends that of a previous study (Brockmann et al., Nature 2006) on the discovery of scaling laws of human travel by an order of magnitude and permits an approach to multiscale human transportation from a network perspective.

  20. Geographic variation in marine turtle fibropapillomatosis.

    PubMed

    Greenblatt, Rebecca J; Work, Thierry M; Dutton, Peter; Sutton, Claudia A; Spraker, Terry R; Casey, Rufina N; Diez, Carlos E; Parker, Denise; St Leger, Judy; Balazs, George H; Casey, James W

    2005-09-01

    We document three examples of fibropapillomatosis by histology, quantitative polymerase chain reaction (qPCR), and sequence analysis from three different geographic areas. Tumors compatible in morphology with fibropapillomatosis were seen in green turtles from Puerto Rico and San Diego (California) and in a hybrid loggerhead/ hawksbill turtle from Florida Bay (Florida). Tumors were confirmed as fibropapillomas on histology, although severity of disease varied between cases. Polymerase chain reaction (PCR) analyses revealed infection with the fibropapilloma-associated turtle herpesvirus (FPTHV) in all cases, albeit at highly variable copy numbers per cell. Alignment of a portion of the polymerase gene from each fibropapilloma-associated turtle herpesvirus isolate demonstrated geographic variation in sequence. These cases illustrate geographic variation in both the pathology and the virology of fibropapillomatosis.

  1. Geographic variation in marine turtle fibropapillomatosis

    USGS Publications Warehouse

    Greenblatt, R.J.; Work, Thierry M.; Dutton, P.; Sutton, C.A.; Spraker, T.R.; Casey, R.N.; Diez, C.E.; Parker, Dana C.; St. Ledger, J.; Balazs, G.H.; Casey, J.W.

    2005-01-01

    We document three examples of fibropapillomatosis by histology, quantitative polymerase chain reaction (qPCR), and sequence analysis from three different geographic areas. Tumors compatible in morphology with fibropapillomatosis were seen in green turtles from Puerto Rico and San Diego (California) and in a hybrid loggerhead/ hawksbill turtle from Florida Bay (Florida). Tumors were confirmed as fibropapillomas on histology, although severity of disease varied between cases. Polymerase chain reaction (PCR) analyses revealed infection with the fibropapilloma-associated turtle herpesvirus (FPTHV) in all cases, albeit at highly variable copy numbers per cell. Alignment of a portion of the polymerase gene from each fibropapilloma-associated turtle herpesvirus isolate demonstrated geographic variation in sequence. These cases illustrate geographic variation in both the pathology and the virology of fibropapillomatosis.

  2. Global change: Geographical approaches (A Review)*

    PubMed Central

    Kotlyakov, V. M.; Mather, J. R.; Sdasyuk, G. V.; White, G. F.

    1988-01-01

    The International Geosphere Biosphere Program sponsored by the International Council of Scientific Unions is directing attention to geophysical and biological change as influenced by human modifications in global energy and mass exchanges. Geographers in the Soviet Union and the United States have joined in critical appraisal of their experience in studying environmental change. This initial report is on some promising approaches, such as the reconstruction of earlier landscape processes, modeling of the dynamics of present-day landscapes, analysis of causes and consequences of anthropogenic changes in specified regions, appraisal of social response to change, and enhanced geographic information systems supported by detailed site studies. PMID:16593971

  3. Location of geographical objects in crisis situations

    NASA Astrophysics Data System (ADS)

    Rybansky, M.; Kratochvil, V.

    2014-02-01

    This article summarizes the various expressions of object positioning using different coordinate data and different methods, such as use of maps, exploiting the properties of digital Global System for Mobile Communications (GSM) networks, Global Navigational Satellite Systems (GNSS), Inertial Navigation Systems (INS), Inertial Measurement Systems (IMS), hybrid methods and non-contact (remote sensing) methods; all with varying level of accuracy. Furthermore, the article describes some geographical identifiers and verbal means to describe location of geographical objects such as settlements, rivers, forest, roads, etc. All of the location methods have some advantages and disadvantages, especially in emergency situations, when usually the crisis management has a lack of time in a decision process.

  4. Geographical variation in Plasmodium vivax relapse

    PubMed Central

    2014-01-01

    Background Plasmodium vivax has the widest geographic distribution of the human malaria parasites and nearly 2.5 billion people live at risk of infection. The control of P. vivax in individuals and populations is complicated by its ability to relapse weeks to months after initial infection. Strains of P. vivax from different geographical areas are thought to exhibit varied relapse timings. In tropical regions strains relapse quickly (three to six weeks), whereas those in temperate regions do so more slowly (six to twelve months), but no comprehensive assessment of evidence has been conducted. Here observed patterns of relapse periodicity are used to generate predictions of relapse incidence within geographic regions representative of varying parasite transmission. Methods A global review of reports of P. vivax relapse in patients not treated with a radical cure was conducted. Records of time to first P. vivax relapse were positioned by geographic origin relative to expert opinion regions of relapse behaviour and epidemiological zones. Mixed-effects meta-analysis was conducted to determine which geographic classification best described the data, such that a description of the pattern of relapse periodicity within each region could be described. Model outputs of incidence and mean time to relapse were mapped to illustrate the global variation in relapse. Results Differences in relapse periodicity were best described by a historical geographic classification system used to describe malaria transmission zones based on areas sharing zoological and ecological features. Maps of incidence and time to relapse showed high relapse frequency to be predominant in tropical regions and prolonged relapse in temperate areas. Conclusions The results indicate that relapse periodicity varies systematically by geographic region and are categorized by nine global regions characterized by similar malaria transmission dynamics. This indicates that relapse may be an adaptation evolved to

  5. Geographic information system/watershed model interface

    USGS Publications Warehouse

    Fisher, Gary T.

    1989-01-01

    Geographic information systems allow for the interactive analysis of spatial data related to water-resources investigations. A conceptual design for an interface between a geographic information system and a watershed model includes functions for the estimation of model parameter values. Design criteria include ease of use, minimal equipment requirements, a generic data-base management system, and use of a macro language. An application is demonstrated for a 90.1-square-kilometer subbasin of the Patuxent River near Unity, Maryland, that performs automated derivation of watershed parameters for hydrologic modeling.

  6. Enhancing robustness and immunization in geographical networks

    SciTech Connect

    Huang Liang; Department of Physics, Lanzhou University, Lanzhou 730000; Yang Kongqing

    2007-03-15

    We find that different geographical structures of networks lead to varied percolation thresholds, although these networks may have similar abstract topological structures. Thus, strategies for enhancing robustness and immunization of a geographical network are proposed. Using the generating function formalism, we obtain an explicit form of the percolation threshold q{sub c} for networks containing arbitrary order cycles. For three-cycles, the dependence of q{sub c} on the clustering coefficients is ascertained. The analysis substantiates the validity of the strategies with analytical evidence.

  7. [Geographic data for Neotropical bats (Chiroptera)].

    PubMed

    Noguera-Urbano, Elkin A; Escalante, Tania

    2014-03-01

    The global effort to digitize biodiversity occurrence data from collections, museums and other institutions has stimulated the development of important tools to improve the knowledge and conservation of biodiversity. The Global Biodiversity Information Facility (GBIF) enables and opens access to biodiversity data of 321 million of records, from 379 host institutions. Neotropical bats are a highly diverse and specialized group, and the geographic information about them is increasing since few years ago, but there are a few reports about this topic. The aim of this study was to analyze the number of digital records in GBIF of Neotropical bats with distribution in 21 American countries, evaluating their nomenclatural and geographical consistence at scale of country. Moreover, we evaluated the gaps of information on 1 degrees latitude x 1 degrees longitude grids cells. There were over 1/2 million records, but 58% of them have no latitude and longitude data; and 52% full fit nomenclatural and geographic evaluation. We estimated that there are no records in 54% of the analyzed area; the principal gaps are in biodiversity hotspots like the Colombian and Brazilian Amazonia and Southern Venezuela. In conclusion, our study suggests that available data on GBIF have nomenclatural and geographic biases. GBIF data represent partially the bat species richness and the main gaps in information are in South America.

  8. Geography and Geographical Information Science: Interdisciplinary Integrators

    ERIC Educational Resources Information Center

    Ellul, Claire

    2015-01-01

    To understand how Geography and Geographical Information Science (GIS) can contribute to Interdisciplinary Research (IDR), it is relevant to articulate the differences between the different types of such research. "Multidisciplinary" researchers work in a "parallel play" mode, completing work in their disciplinary work streams…

  9. Data Representations for Geographic Information Systems.

    ERIC Educational Resources Information Center

    Shaffer, Clifford A.

    1992-01-01

    Surveys the field and literature of geographic information systems (GIS) and spatial data representation as it relates to GIS. Highlights include GIS terms, data types, and operations; vector representations and raster, or grid, representations; spatial indexing; elevation data representations; large spatial databases; and problem areas and future…

  10. Geographic Analysis of Neurosurgery Workforce in Korea.

    PubMed

    Park, Hye Ran; Park, Sukh Que; Kim, Jae Hyun; Hwang, Jae Chan; Lee, Gwang Soo; Chang, Jae-Chil

    2018-01-01

    In respect of the health and safety of the public, universal access to health care is an issue of the greatest importance. The geographic distribution of doctors is one of the important factors contributing to access to health care. The aim of this study is to assess the imbalances in the geographic distribution of neurosurgeons across Korea. Population data was obtained from the National Statistical Office. We classified geographic groups into 7 metropolitan cities, 78 non-metropolitan cities, and 77 rural areas. The number of doctors and neurosurgeons per 100000 populations in each county unit was calculated using the total number of doctors and neurosurgeons at the country level from 2009 to 2015. The density levels of neurosurgeon and doctor were calculated and depicted in maps. Between 2009 and 2015, the number of neurosurgeons increased from 2002 to 2557, and the ratio of neurosurgeons per 100000 populations increased from 4.02 to 4.96. The number of neurosurgeons per 100000 populations was highest in metropolitan cities and lowest in rural areas from 2009 to 2015. A comparison of the geographic distribution of neurosurgeons in 2009 and 2015 showed an increase in the regional gap. The neurosurgeon density was affected by country unit characteristics ( p =0.000). Distribution of neurosurgeons throughout Korea is uneven. Neurosurgeons are being increasingly concentrated in a limited number of metropolitan cities. This phenomenon will need to be accounted when planning for a supply of neurosurgeons, allocation of resources and manpower, and the provision of regional neurosurgical services.

  11. The National Geographic Society's Teaching Geography Project.

    ERIC Educational Resources Information Center

    Bockenhauer, Mark H.

    1993-01-01

    Contends that the National Geographic Society's Teaching Geography Project is an inservice teacher education success story. Describes the origins, objectives, and development of the project. Summarizes the impact of the project and contends that its success is the result of the workshop format and guided practice in instructional strategies. (CFR)

  12. Validating a Geographical Image Retrieval System.

    ERIC Educational Resources Information Center

    Zhu, Bin; Chen, Hsinchun

    2000-01-01

    Summarizes a prototype geographical image retrieval system that demonstrates how to integrate image processing and information analysis techniques to support large-scale content-based image retrieval. Describes an experiment to validate the performance of this image retrieval system against that of human subjects by examining similarity analysis…

  13. The Geographic Polarization of American Voters

    ERIC Educational Resources Information Center

    Pearson-Merkowitz, Shanna; Lang, Corey

    2016-01-01

    For the past two decades, the presidency and both houses of Congress have been hotly contested by the two major political parties. Yet, geographically, the United States seems to be increasingly marked by "red" areas where the Democratic Party lacks any ability to even dream of winning office and "blue" areas where the…

  14. Geographic Variation in Condom Availability and Accessibility.

    PubMed

    Shacham, Enbal; J Nelson, Erik; Schulte, Lauren; Bloomfield, Mark; Murphy, Ryan

    2016-12-01

    Identifying predictors that contribute to geographic disparities in sexually transmitted infections (STIs) is necessary in order to reduce disparities. This study assesses the spatial relationship condom availability and accessibility in order to better identify determinants of geographic disparities in STIs. We conducted a telephone-based audit among potential-condom selling establishments. Descriptive analyses were conducted to detect differences in condom-selling characteristics by stores and by store type. Geocoding, mapping, and spatial analysis were conducted to measure the availability of condoms. A total of 850 potential condom-selling establishments participated in the condom availability and accessibility audit in St. Louis city; 29 % sold condoms. There were several significant geographic clusters of stores identified across the study area. The first consisted of fewer convenience stores and gas stations that sold condoms in the northern section of the city, whereas condoms were less likely to be sold in non-convenience store settings in the southwestern and central parts of the city. Additionally, locations that distributed free condoms clustered significantly in city center. However, there was a dearth of businesses that were neither convenience stores nor gas stations in the northern region of the city, which also had the highest concentration of condoms sold. This initial study was conducted to provide evidence that condom availability and accessibility differ by geographic region, and likely are a determinant of social norms surrounding condom use and ultimately impact STI rates.

  15. Using Educational Tourism in Geographical Education

    ERIC Educational Resources Information Center

    Prakapiene, Dalia; Olberkyte, Loreta

    2013-01-01

    The article analyses and defines the concept of educational tourism, presents the structure of the concept and looks into the opportunities for using educational tourism in geographical education. In order to reveal such opportunities a research was carried out in the Lithuanian national and regional parks using the qualitative method of content…

  16. Enhancing Geographic Learning and Literacy through Filmmaking

    ERIC Educational Resources Information Center

    Dando, Christina E.; Chadwick, Jacob J.

    2014-01-01

    In this media-saturated society, students need to think more critically about the media they encounter and that they are producing. Through filmmaking, students can link geographic theory and the real world, bridging the distance from readings/lectures/discussions to the geography on the ground, making the abstract concrete. But constructing films…

  17. Representing Historical Knowledge in Geographic Information Systems

    ERIC Educational Resources Information Center

    Grossner, Karl Eric

    2010-01-01

    A growing number of historical scholars in social science and humanities fields are using geographic information systems (GIS) to help investigate spatial questions and map their findings. The nature of historical data and historiographic practices present several challenges in using GIS that have been addressed only partially to date. For…

  18. Teaching Geographic Field Methods Using Paleoecology

    ERIC Educational Resources Information Center

    Walsh, Megan K.

    2014-01-01

    Field-based undergraduate geography courses provide numerous pedagogical benefits including an opportunity for students to acquire employable skills in an applied context. This article presents one unique approach to teaching geographic field methods using paleoecological research. The goals of this course are to teach students key geographic…

  19. Geographic Education in Turkish High Schools

    ERIC Educational Resources Information Center

    Tas, Halil I.

    2005-01-01

    This paper presents a review of geographic curricula, teaching methods, materials and assessments in Turkish high schools. Geopolitics and political instability have contributed to large fluctuations in emphasis on geography in Turkish education and have also affected the content of the geography curriculum.

  20. Frontiers in Geographical Teaching. Second Edition.

    ERIC Educational Resources Information Center

    Chorley, Richard J., Ed.; Haggett, Peter, Ed.

    Composed of three parts, "Concepts,""Techniques," and "Teaching," this volume of essays by British geographers emerged from the editors' geography education courses and symposia at Cambridge University. It is addressed to two questions: what is happening in geography? and, what impact does this have on school…

  1. The Geographic Distribution of Indochinese Refugees.

    ERIC Educational Resources Information Center

    Forbes, Susan

    This paper presents information regarding the geographic distribution of Indochinese refugees in the United States and how it compares to that of the overall U.S. population and the non-refugee legal immigrant population. The following information is reported: Seventy percent of all Indochinese refugees currently reside in 10 States, with…

  2. Diversity, Disability, and Geographic Digital Divide

    ERIC Educational Resources Information Center

    Sumari, Melati; Carr, Erika; Ndebe-Ngovo, Manjerngie

    2006-01-01

    The phenomenon called digital divide was the focus of this paper. Diversity, disability, and geographical digital divide were relevant to this collaborative project. An extensive review of the literature was conducted for the completion of this project. The evidence for the digital divide in terms of race, level of education, and gender in the…

  3. Threading One's Way Through the Geographic Region.

    ERIC Educational Resources Information Center

    Thomas, Paul F.

    1982-01-01

    Designed for students in grades 7 through 12, the paper presents illustrative resource materials for teaching concepts related to geographic regions. Emphasis is on giving students an understanding of the interrelationship between regional characteristics and human behavior. The paper introduces students to the following notions: environmental…

  4. Displaying Geographically-Based Domestic Statistics

    NASA Technical Reports Server (NTRS)

    Quann, J.; Dalton, J.; Banks, M.; Helfer, D.; Szczur, M.; Winkert, G.; Billingsley, J.; Borgstede, R.; Chen, J.; Chen, L.; hide

    1982-01-01

    Decision Information Display System (DIDS) is rapid-response information-retrieval and color-graphics display system. DIDS transforms tables of geographically-based domestic statistics (such as population or unemployment by county, energy usage by county, or air-quality figures) into high-resolution, color-coded maps on television display screen.

  5. Geographical Study of American Blues Culture

    ERIC Educational Resources Information Center

    Strait, John B.

    2010-01-01

    Music is not often utilized in teaching geography, despite the fact that many scholars orient their research around analyzing both the historical and spatial dimensions of musical expression. This article reports on the use of a teaching module that utilizes blues culture as a lens to understand the geographical history of the United States. The…

  6. Science Fiction for Geographers: Selected Works.

    ERIC Educational Resources Information Center

    Elbow, Gary S.; Martinson, Tom L.

    1980-01-01

    Explains how college level teachers of geography can use works of science fiction to help students understand geographical settings and create impressionistic pictures of a given region in their minds. Particular areas in which science fiction is useful include invented terrestrial landscapes, specialized extraterrestrial landscapes, disaster…

  7. Geographical distribution of HCV genotypes in Mexico.

    PubMed

    Sánchez-Avila, Juan Francisco; González, Elizabeth; Vázquez, Victoria; Suárez, Susana; Uribe, Misael

    2007-01-01

    Chronic hepatitis C (CHC) is the second cause of endstage liver disease in our country and one of the main indications of liver transplantation. Hepatitis C virus (HCV) genotype is the principal prognostic factor and the determinant of the therapeutic scheme. In our country few data exist regarding the prevalence of HCV infection and genotype distribution in the Mexican Republic has not been determined. The aim of this study was to characterize the prevalence of the different HCV genotypes and to explore their geographical distribution. Mexican patients with hepatitis C infection, detected throughout the country between 2003 and 2006, were included. All samples were analyzed by a central laboratory and Hepatitis C genotype was identified by Line Immuno Probe Assay in PCR positive samples (Versant Line Probe Assay Quest Diagnostics Nichols Institute, San Juan Capistrano CA). Data were analyzed according to the four geographical areas in Mexico. One thousand three hundred and ninety CHC patients were included. The most frequent genotype detected was genotype 1 (69%) followed by genotype 2 (21.4%) and genotype 3 (9.2%). Genotype 4 and 5 were infrequent. There was no subject infected with genotype 6. Genotype 1 and 2 exhibit very similar distribution in all geographical areas. Genotype 3 infected patients were more frequent in the North region (52%) compared with other areas:center-western (30%), center (17%), South-South east (1%) (p < 0.001). The most prevalent HCV genotype in Mexico is genotype 1. Geographical distribution of HCV genotypes in the four geographical areas in Mexico is not homogenous with a greater frequency of genotype3 in the north region. This difference could be related to the global changes of risk factors for HCV infection.

  8. Geographic variation in gorilla limb bones.

    PubMed

    Jabbour, Rebecca S; Pearman, Tessa L

    2016-06-01

    Gorilla systematics has received increased attention over recent decades from primatologists, conservationists, and paleontologists. Studies of geographic variation in DNA, skulls, and teeth have led to new taxonomic proposals, such as recognition of two gorilla species, Gorilla gorilla (western gorilla) and Gorilla beringei (eastern gorilla). Postcranial differences between mountain gorillas (G. beringei beringei) and western lowland gorillas (G. g. gorilla) have a long history of study, but differences between the limb bones of the eastern and western species have not yet been examined with an emphasis on geographic variation within each species. In addition, proposals for recognition of the Cross River gorilla as Gorilla gorilla diehli and gorillas from Tshiaberimu and Kahuzi as G. b. rex-pymaeorum have not been evaluated in the context of geographic variation in the forelimb and hindlimb skeletons. Forty-three linear measurements were collected from limb bones of 266 adult gorillas representing populations of G. b. beringei, Gorilla beringei graueri, G. g. gorilla, and G. g. diehli in order to investigate geographic diversity. Skeletal elements included the humerus, radius, third metacarpal, third proximal hand phalanx, femur, tibia, calcaneus, first metatarsal, third metatarsal, and third proximal foot phalanx. Comparisons of means and principal components analyses clearly differentiate eastern and western gorillas, indicating that eastern gorillas have absolutely and relatively smaller hands and feet, among other differences. Gorilla subspecies and populations cluster consistently by species, although G. g. diehli may be similar to the eastern gorillas in having small hands and feet. The subspecies of G. beringei are distinguished less strongly and by different variables than the two gorilla species. Populations of G. b. graueri are variable, and Kahuzi and Tshiaberimu specimens do not cluster together. Results support the possible influence of

  9. Immigration and geographic access to prenatal clinics in Brooklyn, NY: a geographic information systems analysis.

    PubMed

    McLafferty, Sara; Grady, Sue

    2005-04-01

    We compared levels of geographic access to prenatal clinics in Brooklyn, NY, between immigrant and US-born mothers and among immigrant groups by country of birth. We used birth data to characterize the spatial distribution of mothers and kernel estimation to measure clinic density within a 2-mile radius of each mother. Results showed that geographic access to clinics differs substantially by country of birth. Certain groups (e.g., Pakistani, Bangladeshi) have relatively poor geographic access despite a high need for prenatal care.

  10. ERBE Geographic Scene and Monthly Snow Data

    NASA Technical Reports Server (NTRS)

    Coleman, Lisa H.; Flug, Beth T.; Gupta, Shalini; Kizer, Edward A.; Robbins, John L.

    1997-01-01

    The Earth Radiation Budget Experiment (ERBE) is a multisatellite system designed to measure the Earth's radiation budget. The ERBE data processing system consists of several software packages or sub-systems, each designed to perform a particular task. The primary task of the Inversion Subsystem is to reduce satellite altitude radiances to fluxes at the top of the Earth's atmosphere. To accomplish this, angular distribution models (ADM's) are required. These ADM's are a function of viewing and solar geometry and of the scene type as determined by the ERBE scene identification algorithm which is a part of the Inversion Subsystem. The Inversion Subsystem utilizes 12 scene types which are determined by the ERBE scene identification algorithm. The scene type is found by combining the most probable cloud cover, which is determined statistically by the scene identification algorithm, with the underlying geographic scene type. This Contractor Report describes how the geographic scene type is determined on a monthly basis.

  11. Ethics and geographical equity in health care

    PubMed Central

    Rice, N.; Smith, P.

    2001-01-01

    Important variations in access to health care and health outcomes are associated with geography, giving rise to profound ethical concerns. This paper discusses the consequences of such concerns for the allocation of health care finance to geographical regions. Specifically, it examines the ethical drivers underlying capitation systems, which have become the principal method of allocating health care finance to regions in most countries. Although most capitation systems are based on empirical models of health care expenditure, there is much debate about which needs factors to include in (or exclude from) such models. This concern with legitimate and illegitimate drivers of health care expenditure reflects the ethical concerns underlying the geographical distribution of health care finance. Key Words: Health economics • resource allocation • ethics of regional health care finance • capitation systems PMID:11479357

  12. Ecologic and Geographic Distribution of Filovirus Disease

    PubMed Central

    Bauer, John T.; Mills, James N.

    2004-01-01

    We used ecologic niche modeling of outbreaks and sporadic cases of filovirus-associated hemorrhagic fever (HF) to provide a large-scale perspective on the geographic and ecologic distributions of Ebola and Marburg viruses. We predicted that filovirus would occur across the Afrotropics: Ebola HF in the humid rain forests of central and western Africa, and Marburg HF in the drier and more open areas of central and eastern Africa. Most of the predicted geographic extent of Ebola HF has been observed; Marburg HF has the potential to occur farther south and east. Ecologic conditions appropriate for Ebola HF are also present in Southeast Asia and the Philippines, where Ebola Reston is hypothesized to be distributed. This first large-scale ecologic analysis provides a framework for a more informed search for taxa that could constitute the natural reservoir for this virus family. PMID:15078595

  13. Transmission and visualization of large geographical maps

    NASA Astrophysics Data System (ADS)

    Zhang, Liqiang; Zhang, Liang; Ren, Yingchao; Guo, Zhifeng

    Transmission and visualization of large geographical maps have become a challenging research issue in GIS applications. This paper presents an efficient and robust way to simplify large geographical maps using frame buffers and Voronoi diagrams. The topological relationships are kept during the simplification by removing the Voronoi diagram's self-overlapped regions. With the simplified vector maps, we establish different levels of detail (LOD) models of these maps. Then we introduce a client/server architecture which integrates our out-of-core algorithm, progressive transmission and rendering scheme based on computer graphics hardware. The architecture allows the viewers to view different regions interactively at different LODs on the network. Experimental results show that our proposed scheme provides an effective way for powerful transmission and manipulation of large maps.

  14. Quantitative Social Dialectology: Explaining Linguistic Variation Geographically and Socially

    PubMed Central

    Wieling, Martijn; Nerbonne, John; Baayen, R. Harald

    2011-01-01

    In this study we examine linguistic variation and its dependence on both social and geographic factors. We follow dialectometry in applying a quantitative methodology and focusing on dialect distances, and social dialectology in the choice of factors we examine in building a model to predict word pronunciation distances from the standard Dutch language to 424 Dutch dialects. We combine linear mixed-effects regression modeling with generalized additive modeling to predict the pronunciation distance of 559 words. Although geographical position is the dominant predictor, several other factors emerged as significant. The model predicts a greater distance from the standard for smaller communities, for communities with a higher average age, for nouns (as contrasted with verbs and adjectives), for more frequent words, and for words with relatively many vowels. The impact of the demographic variables, however, varied from word to word. For a majority of words, larger, richer and younger communities are moving towards the standard. For a smaller minority of words, larger, richer and younger communities emerge as driving a change away from the standard. Similarly, the strength of the effects of word frequency and word category varied geographically. The peripheral areas of the Netherlands showed a greater distance from the standard for nouns (as opposed to verbs and adjectives) as well as for high-frequency words, compared to the more central areas. Our findings indicate that changes in pronunciation have been spreading (in particular for low-frequency words) from the Hollandic center of economic power to the peripheral areas of the country, meeting resistance that is stronger wherever, for well-documented historical reasons, the political influence of Holland was reduced. Our results are also consistent with the theory of lexical diffusion, in that distances from the Hollandic norm vary systematically and predictably on a word by word basis. PMID:21912639

  15. Quantitative social dialectology: explaining linguistic variation geographically and socially.

    PubMed

    Wieling, Martijn; Nerbonne, John; Baayen, R Harald

    2011-01-01

    In this study we examine linguistic variation and its dependence on both social and geographic factors. We follow dialectometry in applying a quantitative methodology and focusing on dialect distances, and social dialectology in the choice of factors we examine in building a model to predict word pronunciation distances from the standard Dutch language to 424 Dutch dialects. We combine linear mixed-effects regression modeling with generalized additive modeling to predict the pronunciation distance of 559 words. Although geographical position is the dominant predictor, several other factors emerged as significant. The model predicts a greater distance from the standard for smaller communities, for communities with a higher average age, for nouns (as contrasted with verbs and adjectives), for more frequent words, and for words with relatively many vowels. The impact of the demographic variables, however, varied from word to word. For a majority of words, larger, richer and younger communities are moving towards the standard. For a smaller minority of words, larger, richer and younger communities emerge as driving a change away from the standard. Similarly, the strength of the effects of word frequency and word category varied geographically. The peripheral areas of the Netherlands showed a greater distance from the standard for nouns (as opposed to verbs and adjectives) as well as for high-frequency words, compared to the more central areas. Our findings indicate that changes in pronunciation have been spreading (in particular for low-frequency words) from the Hollandic center of economic power to the peripheral areas of the country, meeting resistance that is stronger wherever, for well-documented historical reasons, the political influence of Holland was reduced. Our results are also consistent with the theory of lexical diffusion, in that distances from the Hollandic norm vary systematically and predictably on a word by word basis.

  16. Plastome data reveal multiple geographic origins of Quercus Group Ilex

    PubMed Central

    Grimm, Guido W.; Papini, Alessio; Vessella, Federico; Cardoni, Simone; Tordoni, Enrico; Piredda, Roberta; Franc, Alain; Denk, Thomas

    2016-01-01

    Nucleotide sequences from the plastome are currently the main source for assessing taxonomic and phylogenetic relationships in flowering plants and their historical biogeography at all hierarchical levels. One major exception is the large and economically important genus Quercus (oaks). Whereas differentiation patterns of the nuclear genome are in agreement with morphology and the fossil record, diversity patterns in the plastome are at odds with established taxonomic and phylogenetic relationships. However, the extent and evolutionary implications of this incongruence has yet to be fully uncovered. The DNA sequence divergence of four Euro-Mediterranean Group Ilex oak species (Quercus ilex L., Q. coccifera L., Q. aucheri Jaub. & Spach., Q. alnifolia Poech.) was explored at three chloroplast markers (rbcL, trnK/matK, trnH-psbA). Phylogenetic relationships were reconstructed including worldwide members of additional 55 species representing all Quercus subgeneric groups. Family and order sequence data were harvested from gene banks to better frame the observed divergence in larger taxonomic contexts. We found a strong geographic sorting in the focal group and the genus in general that is entirely decoupled from species boundaries. High plastid divergence in members of Quercus Group Ilex, including haplotypes shared with related, but long isolated oak lineages, point towards multiple geographic origins of this group of oaks. The results suggest that incomplete lineage sorting and repeated phases of asymmetrical introgression among ancestral lineages of Group Ilex and two other main Groups of Eurasian oaks (Cyclobalanopsis and Cerris) caused this complex pattern. Comparison with the current phylogenetic synthesis also suggests an initial high- versus mid-latitude biogeographic split within Quercus. High plastome plasticity of Group Ilex reflects geographic area disruptions, possibly linked with high tectonic activity of past and modern distribution ranges, that did not

  17. History Shaped the Geographic Distribution of Genomic Admixture on the Island of Puerto Rico

    PubMed Central

    Via, Marc; Gignoux, Christopher R.; Roth, Lindsey A.; Fejerman, Laura; Galanter, Joshua; Choudhry, Shweta; Toro-Labrador, Gladys; Viera-Vera, Jorge; Oleksyk, Taras K.; Beckman, Kenneth; Ziv, Elad; Risch, Neil

    2011-01-01

    Contemporary genetic variation among Latin Americans human groups reflects population migrations shaped by complex historical, social and economic factors. Consequently, admixture patterns may vary by geographic regions ranging from countries to neighborhoods. We examined the geographic variation of admixture across the island of Puerto Rico and the degree to which it could be explained by historic and social events. We analyzed a census-based sample of 642 Puerto Rican individuals that were genotyped for 93 ancestry informative markers (AIMs) to estimate African, European and Native American ancestry. Socioeconomic status (SES) data and geographic location were obtained for each individual. There was significant geographic variation of ancestry across the island. In particular, African ancestry demonstrated a decreasing East to West gradient that was partially explained by historical factors linked to the colonial sugar plantation system. SES also demonstrated a parallel decreasing cline from East to West. However, at a local level, SES and African ancestry were negatively correlated. European ancestry was strongly negatively correlated with African ancestry and therefore showed patterns complementary to African ancestry. By contrast, Native American ancestry showed little variation across the island and across individuals and appears to have played little social role historically. The observed geographic distributions of SES and genetic variation relate to historical social events and mating patterns, and have substantial implications for the design of studies in the recently admixed Puerto Rican population. More generally, our results demonstrate the importance of incorporating social and geographic data with genetics when studying contemporary admixed populations. PMID:21304981

  18. Knowing what and where: TMS evidence for the dual neural basis of geographical knowledge.

    PubMed

    Hoffman, Paul; Crutch, Sebastian

    2016-02-01

    All animals acquire knowledge about the topography of their immediate environment through direct exploration. Uniquely, humans also acquire geographical knowledge indirectly through exposure to maps and verbal information, resulting in a rich database of global geographical knowledge. We used transcranial magnetic stimulation to investigate the structure and neural basis of this critical but poorly understood component of semantic knowledge. Participants completed tests of geographical knowledge that probed either information about spatial locations (e.g., France borders Spain) or non-spatial taxonomic information (e.g., France is a country). TMS applied to the anterior temporal lobe, a region that codes conceptual knowledge for words and objects, had a general disruptive effect on the geographical tasks. In contrast, stimulation of the intraparietal sulcus (IPS), a region involved in the coding of spatial and numerical information, had a highly selective effect on spatial geographical decisions but no effect on taxonomic judgements. Our results establish that geographical concepts lie at the intersection of two distinct neural representation systems, and provide insights into how the interaction of these systems shape our understanding of the world. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Methodology for classification of geographical features with remote sensing images: Application to tidal flats

    NASA Astrophysics Data System (ADS)

    Revollo Sarmiento, G. N.; Cipolletti, M. P.; Perillo, M. M.; Delrieux, C. A.; Perillo, Gerardo M. E.

    2016-03-01

    Tidal flats generally exhibit ponds of diverse size, shape, orientation and origin. Studying the genesis, evolution, stability and erosive mechanisms of these geographic features is critical to understand the dynamics of coastal wetlands. However, monitoring these locations through direct access is hard and expensive, not always feasible, and environmentally damaging. Processing remote sensing images is a natural alternative for the extraction of qualitative and quantitative data due to their non-invasive nature. In this work, a robust methodology for automatic classification of ponds and tidal creeks in tidal flats using Google Earth images is proposed. The applicability of our method is tested in nine zones with different morphological settings. Each zone is processed by a segmentation stage, where ponds and tidal creeks are identified. Next, each geographical feature is measured and a set of shape descriptors is calculated. This dataset, together with a-priori classification of each geographical feature, is used to define a regression model, which allows an extensive automatic classification of large volumes of data discriminating ponds and tidal creeks against other various geographical features. In all cases, we identified and automatically classified different geographic features with an average accuracy over 90% (89.7% in the worst case, and 99.4% in the best case). These results show the feasibility of using freely available Google Earth imagery for the automatic identification and classification of complex geographical features. Also, the presented methodology may be easily applied in other wetlands of the world and perhaps employing other remote sensing imagery.

  20. Geographic disparity in kidney transplantation under KAS.

    PubMed

    Zhou, Sheng; Massie, Allan B; Luo, Xun; Ruck, Jessica M; Chow, Eric K H; Bowring, Mary G; Bae, Sunjae; Segev, Dorry L; Gentry, Sommer E

    2017-12-12

    The Kidney Allocation System fundamentally altered kidney allocation, causing a substantial increase in regional and national sharing that we hypothesized might impact geographic disparities. We measured geographic disparity in deceased donor kidney transplant (DDKT) rate under KAS (6/1/2015-12/1/2016), and compared that with pre-KAS (6/1/2013-12/3/2014). We modeled DSA-level DDKT rates with multilevel Poisson regression, adjusting for allocation factors under KAS. Using the model we calculated a novel, improved metric of geographic disparity: the median incidence rate ratio (MIRR) of transplant rate, a measure of DSA-level variation that accounts for patient casemix and is robust to outlier values. Under KAS, MIRR was 1.75 1.81 1.86 for adults, meaning that similar candidates across different DSAs have a median 1.81-fold difference in DDKT rate. The impact of geography was greater than the impact of factors emphasized by KAS: having an EPTS score ≤20% was associated with a 1.40-fold increase (IRR =  1.35 1.40 1.45 , P < .01) and a three-year dialysis vintage was associated with a 1.57-fold increase (IRR =  1.56 1.57 1.59 , P < .001) in transplant rate. For pediatric candidates, MIRR was even more pronounced, at 1.66 1.92 2.27 . There was no change in geographic disparities with KAS (P = .3). Despite extensive changes to kidney allocation under KAS, geography remains a primary determinant of access to DDKT. © 2017 The American Society of Transplantation and the American Society of Transplant Surgeons.

  1. Geographic Analysis of Neurosurgery Workforce in Korea

    PubMed Central

    Park, Hye Ran; Park, Sukh Que; Kim, Jae Hyun; Hwang, Jae Chan; Lee, Gwang Soo; Chang, Jae-Chil

    2018-01-01

    Objective In respect of the health and safety of the public, universal access to health care is an issue of the greatest importance. The geographic distribution of doctors is one of the important factors contributing to access to health care. The aim of this study is to assess the imbalances in the geographic distribution of neurosurgeons across Korea. Methods Population data was obtained from the National Statistical Office. We classified geographic groups into 7 metropolitan cities, 78 non-metropolitan cities, and 77 rural areas. The number of doctors and neurosurgeons per 100000 populations in each county unit was calculated using the total number of doctors and neurosurgeons at the country level from 2009 to 2015. The density levels of neurosurgeon and doctor were calculated and depicted in maps. Results Between 2009 and 2015, the number of neurosurgeons increased from 2002 to 2557, and the ratio of neurosurgeons per 100000 populations increased from 4.02 to 4.96. The number of neurosurgeons per 100000 populations was highest in metropolitan cities and lowest in rural areas from 2009 to 2015. A comparison of the geographic distribution of neurosurgeons in 2009 and 2015 showed an increase in the regional gap. The neurosurgeon density was affected by country unit characteristics (p=0.000). Conclusion Distribution of neurosurgeons throughout Korea is uneven. Neurosurgeons are being increasingly concentrated in a limited number of metropolitan cities. This phenomenon will need to be accounted when planning for a supply of neurosurgeons, allocation of resources and manpower, and the provision of regional neurosurgical services. PMID:29354242

  2. Geographic Information Systems and travel health.

    PubMed

    Bauer, Irmgard L; Puotinen, Marji

    2002-01-01

    Questions dealing with space and/or location have always been integral to understanding and addressing health issues, such as charting the spread of a disease. Health researchers have traditionally used paper maps to explore the spatial dimensions of health. However, due to advances in technology, it is now possible to ask such questions using a suite of computer-based methods and tools that are collectively known as a Geographic Information System (GIS).

  3. U-PLANT GEOGRAPHIC ZONE CLEANUP PROTOTYPE

    SciTech Connect

    ROMINE, L.D.

    2006-02-01

    The U Plant geographic zone (UPZ) occupies 0.83 square kilometers on the Hanford Site Central Plateau (200 Area). It encompasses the U Plant canyon (221-U Facility), ancillary facilities that supported the canyon, soil waste sites, and underground pipelines. The UPZ cleanup initiative coordinates the cleanup of the major facilities, ancillary facilities, waste sites, and contaminated pipelines (collectively identified as ''cleanup items'') within the geographic zone. The UPZ was selected as a geographic cleanup zone prototype for resolving regulatory, technical, and stakeholder issues and demonstrating cleanup methods for several reasons: most of the area is inactive, sufficient characterization information is availablemore » to support decisions, cleanup of the high-risk waste sites will help protect the groundwater, and the zone contains a representative cross-section of the types of cleanup actions that will be required in other geographic zones. The UPZ cleanup demonstrates the first of 22 integrated zone cleanup actions on the Hanford Site Central Plateau to address threats to groundwater, the environment, and human health. The UPZ contains more than 100 individual cleanup items. Cleanup actions in the zone will be undertaken using multiple regulatory processes and decision documents. Cleanup actions will include building demolition, waste site and pipeline excavation, and the construction of multiple, large engineered barriers. In some cases, different cleanup actions may be taken at item locations that are immediately adjacent to each other. The cleanup planning and field activities for each cleanup item must be undertaken in a coordinated and cohesive manner to ensure effective execution of the UPZ cleanup initiative. The UPZ zone cleanup implementation plan (ZCIP) was developed to address the need for a fundamental integration tool for UPZ cleanup. As UPZ cleanup planning and implementation moves forward, the ZCIP is intended to be a living document that

  4. Geographic Accessibility of Community Pharmacies in Ontario

    PubMed Central

    Law, Michael R.; Dijkstra, Anna; Douillard, Jay A.; Morgan, Steven G.

    2011-01-01

    Background: Proximity is an important component of access to healthcare services. Recent changes in generic pricing in Ontario have caused speculation about pharmacy closures. However, there is little information on the current geographic accessibility of pharmacies. Therefore, we studied geographic access to pharmacies and modelled the impact of possible closures. Methods: We used location data on the 3,352 accredited community pharmacies from the Ontario College of Pharmacists and population estimates at the census dissemination block level. Using network analysis, we determined the share of Ontario's population who reside in a census dissemination block within three road travel distances of a community pharmacy: 800 m (walking), 2 km and 5 km (driving). We then simulated the effects on these measures of 10% to 50% reductions in the number of community pharmacies in Ontario. Results: Approximately 63.6% of the Ontario population reside in a dissemination block located within walking distance of one or more pharmacies; 84.6% and 90.7% reside within 2-km and 5-km driving distances, respectively. Randomly removing 30% of Ontario's community pharmacies reduces these estimates to 56.0%, 81.4% and 89.0% for each distance, respectively; a 50% reduction results in 48.3%, 77.1% and 87.2%, respectively. Conclusions: Pharmacies are geographically accessible for a majority of the Ontario population. Moreover, it appears that modest closures would have only a small impact on geographic access to pharmacies. However, closures may have other impacts on access, such as cost, waiting time and reduced patient choice. PMID:22294990

  5. Geographic Analysis of the Radiation Oncology Workforce

    SciTech Connect

    Aneja, Sanjay; Cancer Outcomes, Policy, and Effectiveness Research Center at Yale, New Haven, CT; Smith, Benjamin D.

    2012-04-01

    Purpose: To evaluate trends in the geographic distribution of the radiation oncology (RO) workforce. Methods and Materials: We used the 1995 and 2007 versions of the Area Resource File to map the ratio of RO to the population aged 65 years or older (ROR) within different health service areas (HSA) within the United States. We used regression analysis to find associations between population variables and 2007 ROR. We calculated Gini coefficients for ROR to assess the evenness of RO distribution and compared that with primary care physicians and total physicians. Results: There was a 24% increase in the RO workforcemore » from 1995 to 2007. The overall growth in the RO workforce was less than that of primary care or the overall physician workforce. The mean ROR among HSAs increased by more than one radiation oncologist per 100,000 people aged 65 years or older, from 5.08 per 100,000 to 6.16 per 100,000. However, there remained consistent geographic variability concerning RO distribution, specifically affecting the non-metropolitan HSAs. Regression analysis found higher ROR in HSAs that possessed higher education (p = 0.001), higher income (p < 0.001), lower unemployment rates (p < 0.001), and higher minority population (p = 0.022). Gini coefficients showed RO distribution less even than for both primary care physicians and total physicians (0.326 compared with 0.196 and 0.292, respectively). Conclusions: Despite a modest growth in the RO workforce, there exists persistent geographic maldistribution of radiation oncologists allocated along socioeconomic and racial lines. To solve problems surrounding the RO workforce, issues concerning both gross numbers and geographic distribution must be addressed.« less

  6. Geographically isolated wetlands: Rethinking a misnomer

    USGS Publications Warehouse

    Mushet, David M.; Calhoun, Aram J.K.; Alexander, Laurie C.; Cohen, Matthew J.; DeKeyser, Edward S.; Fowler, Laurie G.; Lane, Charles R.; Lang, Megan W.; Rains, Mark C.; Walls, Susan

    2015-01-01

    We explore the category “geographically isolated wetlands” (GIWs; i.e., wetlands completely surrounded by uplands at the local scale) as used in the wetland sciences. As currently used, the GIW category (1) hampers scientific efforts by obscuring important hydrological and ecological differences among multiple wetland functional types, (2) aggregates wetlands in a manner not reflective of regulatory and management information needs, (3) implies wetlands so described are in some way “isolated,” an often incorrect implication, (4) is inconsistent with more broadly used and accepted concepts of “geographic isolation,” and (5) has injected unnecessary confusion into scientific investigations and discussions. Instead, we suggest other wetland classification systems offer more informative alternatives. For example, hydrogeomorphic (HGM) classes based on well-established scientific definitions account for wetland functional diversity thereby facilitating explorations into questions of connectivity without an a priori designation of “isolation.” Additionally, an HGM-type approach could be used in combination with terms reflective of current regulatory or policymaking needs. For those rare cases in which the condition of being surrounded by uplands is the relevant distinguishing characteristic, use of terminology that does not unnecessarily imply isolation (e.g., “upland embedded wetlands”) would help alleviate much confusion caused by the “geographically isolated wetlands” misnomer.

  7. A Geographical Heuristic Routing Protocol for VANETs

    PubMed Central

    Urquiza-Aguiar, Luis; Tripp-Barba, Carolina; Aguilar Igartua, Mónica

    2016-01-01

    Vehicular ad hoc networks (VANETs) leverage the communication system of Intelligent Transportation Systems (ITS). Recently, Delay-Tolerant Network (DTN) routing protocols have increased their popularity among the research community for being used in non-safety VANET applications and services like traffic reporting. Vehicular DTN protocols use geographical and local information to make forwarding decisions. However, current proposals only consider the selection of the best candidate based on a local-search. In this paper, we propose a generic Geographical Heuristic Routing (GHR) protocol that can be applied to any DTN geographical routing protocol that makes forwarding decisions hop by hop. GHR includes in its operation adaptations simulated annealing and Tabu-search meta-heuristics, which have largely been used to improve local-search results in discrete optimization. We include a complete performance evaluation of GHR in a multi-hop VANET simulation scenario for a reporting service. Our study analyzes all of the meaningful configurations of GHR and offers a statistical analysis of our findings by means of MANOVA tests. Our results indicate that the use of a Tabu list contributes to improving the packet delivery ratio by around 5% to 10%. Moreover, if Tabu is used, then the simulated annealing routing strategy gets a better performance than the selection of the best node used with carry and forwarding (default operation). PMID:27669254

  8. A Geographical Heuristic Routing Protocol for VANETs.

    PubMed

    Urquiza-Aguiar, Luis; Tripp-Barba, Carolina; Aguilar Igartua, Mónica

    2016-09-23

    Vehicular ad hoc networks (VANETs) leverage the communication system of Intelligent Transportation Systems (ITS). Recently, Delay-Tolerant Network (DTN) routing protocols have increased their popularity among the research community for being used in non-safety VANET applications and services like traffic reporting. Vehicular DTN protocols use geographical and local information to make forwarding decisions. However, current proposals only consider the selection of the best candidate based on a local-search. In this paper, we propose a generic Geographical Heuristic Routing (GHR) protocol that can be applied to any DTN geographical routing protocol that makes forwarding decisions hop by hop. GHR includes in its operation adaptations simulated annealing and Tabu-search meta-heuristics, which have largely been used to improve local-search results in discrete optimization. We include a complete performance evaluation of GHR in a multi-hop VANET simulation scenario for a reporting service. Our study analyzes all of the meaningful configurations of GHR and offers a statistical analysis of our findings by means of MANOVA tests. Our results indicate that the use of a Tabu list contributes to improving the packet delivery ratio by around 5% to 10%. Moreover, if Tabu is used, then the simulated annealing routing strategy gets a better performance than the selection of the best node used with carry and forwarding (default operation).

  9. Geographical assemblages of European raptors and owls

    NASA Astrophysics Data System (ADS)

    López-López, Pascual; Benavent-Corai, José; García-Ripollés, Clara

    2008-09-01

    In this work we look for geographical structure patterns in European raptors (Order: Falconiformes) and owls (Order: Strigiformes). For this purpose we have conducted our research using freely available tools such as statistical software and databases. To perform the study, presence-absence data for the European raptors and owl species (Class Aves) were downloaded from the BirdLife International website. Using the freely available "pvclust" R-package, we applied similarity Jaccard index and cluster analysis in order to delineate biogeographical relationships for European countries. According to the cluster of similarity, we found that Europe is structured into two main geographical assemblages. The larger length branch separated two main groups: one containing Iceland, Greenland and the countries of central, northern and northwestern Europe, and the other group including the countries of eastern, southern and southwestern Europe. Both groups are divided into two main subgroups. According to our results, the European raptors and owls could be considered structured into four meta-communities well delimited by suture zones defined by Remington (1968) [Remington, C.L., 1968. Suture-zones of hybrid interaction between recently joined biotas. Evol. Biol. 2, 321-428]. Climatic oscillations during the Quaternary Ice Ages could explain at least in part the modern geographical distribution of the group.

  10. Geographical variation in cancer survival in England, 1991–2006: an analysis by Cancer Network

    PubMed Central

    Quaresma, Manuela; Coleman, Michel P; Gordon, Emma; Forman, David; Rachet, Bernard

    2011-01-01

    Background Reducing geographical inequalities in cancer survival in England was a key aim of the Calman–Hine Report (1995) and the NHS Cancer Plan (2000). This study assesses whether geographical inequalities changed following these policy developments by analysing the trend in 1-year relative survival in the 28 cancer networks of England. Methods Population-based age-standardised relative survival at 1 year is estimated for 1.4 million patients diagnosed with cancer of the oesophagus, stomach, colon, lung, breast (women) or cervix in England during 1991–2006 and followed up to 2007. Regional and deprivation-specific life tables are built to adjust survival estimates for differences in background mortality. Analysis is divided into three calendar periods: 1991–5, 1996–2000 and 2001–6. Funnel plots are used to assess geographical variation in survival over time. Results One-year relative survival improved for all cancers except cervical cancer. There was a wide geographical variation in survival with generally lower estimates in northern England. This north–south divide became less marked over time, although the overall number of cancer networks that were lower outliers compared with the England value remained stable. Breast cancer was the only cancer for which there was a marked reduction in geographical inequality in survival over time. Conclusion Policy changes over the past two decades coincided with improved relative survival, without an increase in geographical variation. The north–south divide in relative survival became less pronounced over time but geographical inequalities persist. The reduction in geographical inequality in breast cancer survival may be followed by a similar trend for other cancers, provided government recommendations are implemented similarly. PMID:21321064

  11. Job Satisfaction and Pay Satisfaction Levels of University Faculty by Discipline Type and by Geographic Region.

    ERIC Educational Resources Information Center

    Terpstra, David E.; Honoree, Andre L.

    2004-01-01

    This study surveyed approximately 500 faculty across different disciplines from over 100 four- year colleges and universities in the U.S. The primary purpose of the study was to provide some empirical data on the general job satisfaction and pay satisfaction levels of faculty by type of academic discipline and by geographic region. The possible…

  12. Bridging High School and Introductory Undergraduate Courses in Geographic Information Science and Technology

    ERIC Educational Resources Information Center

    Journal of Geography, 2018

    2018-01-01

    This article presents the findings of a study to determine the degree of consistency in what is taught and learned in high school and college-level introductory courses in geographic information science and technology (GIS&T). A content analysis identified sixteen topics that are generally representative of the knowledge, skills, and abilities…

  13. An Assessment of the Use of Geographical Information Systems (GIS) in Teaching Geography in Singapore Schools

    ERIC Educational Resources Information Center

    Yap, Lee Yong; Tan, Geok Chin Ivy; Zhu, Xuan; Wettasinghe, Marissa C.

    2008-01-01

    In 1998, geographical information systems (GIS) were introduced to secondary schools in Singapore as a tool for teaching geography at the secondary and junior college levels. However, general observations and feedback from school teachers suggested that only a small number of secondary schools and junior colleges in Singapore were actually using…

  14. The Study of Geographic Differences in the Prevalence of Disability among Taiwanese Population

    ERIC Educational Resources Information Center

    Lin, Jin-Ding; Li, Chien-De; Lin, Lan-Ping; Hsu, Shang-Wei

    2012-01-01

    The present study analyzes data of the governmental reported general population and population of persons with disabilities from 2002 to 2009, to describe the disability prevalence and to test the overtime change with particular focused on the geographic differences in Taiwan. In average, the disability prevalence was 42.06% (range = 31.06%-80.04%…

  15. Association Between Geographic Access to Cancer Care, Insurance, and Receipt of Chemotherapy: Geographic Distribution of Oncologists and Travel Distance.

    PubMed

    Lin, Chun Chieh; Bruinooge, Suanna S; Kirkwood, M Kelsey; Olsen, Christine; Jemal, Ahmedin; Bajorin, Dean; Giordano, Sharon H; Goldstein, Michael; Guadagnolo, B Ashleigh; Kosty, Michael; Hopkins, Shane; Yu, James B; Arnone, Anna; Hanley, Amy; Stevens, Stephanie; Hershman, Dawn L

    2015-10-01

    Geographic access to care may be associated with receipt of chemotherapy but has not been fully examined. This study sought to evaluate the association between density of oncologists and travel distance and receipt of adjuvant chemotherapy for colon cancer within 90 days of colectomy. Patients in the National Cancer Data Base with stage III colon cancer, diagnosed between 2007 and 2010, and age 18 to 80 years were selected. Generalized estimating equation clustering by hospital service area was conducted to examine the association between geographic access and receipt of oncology services, controlling for patient sociodemographic and clinical characteristics. Of 34,694 patients in the study cohort, 75.7% received adjuvant chemotherapy within 90 days of colectomy. Compared with travel distance less than 12.5 miles, patients who traveled 50 to 249 miles (odds ratio [OR], 0.87; P=.009) or ≥250 miles (OR, 0.36; P<.001) had decreased likelihood of receiving adjuvant chemotherapy. Density level of oncologists was not statistically associated with receipt of adjuvant chemotherapy (low v high density: OR, 0.98; P=.77). When stratifying analyses by insurance status, non-privately insured patients who resided in areas with low density of oncologists were less likely to receive adjuvant chemotherapy (OR, 0.85; P=.03). Increased travel burden was associated with a decreased likelihood of receiving adjuvant chemotherapy, regardless of insurance status. Patients with nonprivate insurance who resided in low-density oncologist areas were less likely to receive adjuvant chemotherapy. If these findings are validated prospectively, interventions to decrease geographic barriers may improve the timeliness and quality of colon cancer treatment. © 2015 by American Society of Clinical Oncology.

  16. Association Between Geographic Access to Cancer Care, Insurance, and Receipt of Chemotherapy: Geographic Distribution of Oncologists and Travel Distance

    PubMed Central

    Lin, Chun Chieh; Bruinooge, Suanna S.; Kirkwood, M. Kelsey; Olsen, Christine; Jemal, Ahmedin; Bajorin, Dean; Giordano, Sharon H.; Goldstein, Michael; Guadagnolo, B. Ashleigh; Kosty, Michael; Hopkins, Shane; Yu, James B.; Arnone, Anna; Hanley, Amy; Stevens, Stephanie; Hershman, Dawn L.

    2015-01-01

    Purpose Geographic access to care may be associated with receipt of chemotherapy but has not been fully examined. This study sought to evaluate the association between density of oncologists and travel distance and receipt of adjuvant chemotherapy for colon cancer within 90 days of colectomy. Patients and Methods Patients in the National Cancer Data Base with stage III colon cancer, diagnosed between 2007 and 2010, and age 18 to 80 years were selected. Generalized estimating equation clustering by hospital service area was conducted to examine the association between geographic access and receipt of oncology services, controlling for patient sociodemographic and clinical characteristics. Results Of 34,694 patients in the study cohort, 75.7% received adjuvant chemotherapy within 90 days of colectomy. Compared with travel distance less than 12.5 miles, patients who traveled 50 to 249 miles (odds ratio [OR], 0.87; P = .009) or ≥ 250 miles (OR, 0.36; P < .001) had decreased likelihood of receiving adjuvant chemotherapy. Density level of oncologists was not statistically associated with receipt of adjuvant chemotherapy (low v high density: OR, 0.98; P = .77). When stratifying analyses by insurance status, non–privately insured patients who resided in areas with low density of oncologists were less likely to receive adjuvant chemotherapy (OR, 0.85; P = .03). Conclusion Increased travel burden was associated with a decreased likelihood of receiving adjuvant chemotherapy, regardless of insurance status. Patients with nonprivate insurance who resided in low-density oncologist areas were less likely to receive adjuvant chemotherapy. If these findings are validated prospectively, interventions to decrease geographic barriers may improve the timeliness and quality of colon cancer treatment. PMID:26304878

  17. KBGIS-2: A knowledge-based geographic information system

    NASA Technical Reports Server (NTRS)

    Smith, T.; Peuquet, D.; Menon, S.; Agarwal, P.

    1986-01-01

    The architecture and working of a recently implemented knowledge-based geographic information system (KBGIS-2) that was designed to satisfy several general criteria for the geographic information system are described. The system has four major functions that include query-answering, learning, and editing. The main query finds constrained locations for spatial objects that are describable in a predicate-calculus based spatial objects language. The main search procedures include a family of constraint-satisfaction procedures that use a spatial object knowledge base to search efficiently for complex spatial objects in large, multilayered spatial data bases. These data bases are represented in quadtree form. The search strategy is designed to reduce the computational cost of search in the average case. The learning capabilities of the system include the addition of new locations of complex spatial objects to the knowledge base as queries are answered, and the ability to learn inductively definitions of new spatial objects from examples. The new definitions are added to the knowledge base by the system. The system is currently performing all its designated tasks successfully, although currently implemented on inadequate hardware. Future reports will detail the performance characteristics of the system, and various new extensions are planned in order to enhance the power of KBGIS-2.

  18. Geographical distributions of lake trout strains stocked in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.; Schaner, Ted

    1996-01-01

    Geographical distributions of lake trout (Salvelinus namaycush) stocked at seven locations in U.S. waters and at four locations in Canadian waters of Lake Ontario were determined from fish caught with gill nets in September in 17 areas of U.S. waters and at 10 fixed locations in Canadian waters in 1986-95. For fish of a given strain stocked at a given location, geographical distributions were not different for immature males and immature females or for mature males and mature females. The proportion of total catch at the three locations nearest the stocking location was higher for mature fish than for immature fish in all 24 available comparisons (sexes combined) and was greater for fish stocked as yearlings than for those stocked as fingerlings in all eight comparisons. Mature fish were relatively widely dispersed from stocking locations indicating that their tendency to return to stocking locations for spawning was weak, and there was no appreciable difference in this tendency among strains. Mature lake trout were uniformly distributed among sampling locations, and the strain composition at stocking locations generally reflected the stocking history 5 to 6 years earlier. Few lake trout moved across Lake Ontario between the north and south shores or between the eastern outlet basin and the main lake basin. Limited dispersal from stocking sites supports the concept of stocking different genetic strains in various parts of the lake with the attributes of each strain selected to match environmental conditions in the portion of the lake where it is stocked.

  19. Geographic structure of European anchovy: A nuclear-DNA study

    NASA Astrophysics Data System (ADS)

    Bouchenak-Khelladi, Yanis; Durand, Jean-Dominique; Magoulas, Antonios; Borsa, Philippe

    2008-08-01

    Atlantic-Mediterranean anchovies were genetically characterized at two polymorphic nuclear loci (intron 6 of two creatine-kinase genes) and compared to reference Engraulis albidus and E. encrasicolus samples from the northern Western Mediterranean to provide new insights into their geographic structure. Northeastern Atlantic anchovy, represented by one sample from the Canary archipelago and one sample from the Alboran Sea, were genetically distinct from Mediterranean E. encrasicolus (Weir and Cockerham's ^θ = 0.027-0.311), indicating geographic isolation from either side of the Almería-Oran oceanographic front. Generally smaller genetic differences were evident among anchovy populations from different sub-basins in the Mediterranean ( ^θ = - 0.019-0.116), the genetic differences between Black Sea and Ionian Sea/Aegean Sea anchovies being the strongest ( ^θ = 0.002-0.116). There was no evidence of the presence of E. albidus in our samples outside Camargue (northern shore of the Western Mediterranean). However, a sample from the southern Western Mediterranean appeared to be genetically intermediate between E. albidus and Mediterranean E. encrasicolus, indicating possible hybridization. Anchovy from the Benguela current system off southern Africa possessed allele frequencies characteristic of E. albidus at one locus and Northeastern Atlantic anchovy at the other locus, suggesting past introgression.

  20. Geographic Variation in Camouflage Specialization by a Decorator Crab.

    PubMed

    Stachowicz, John J; Hay, Mark E

    2000-07-01

    In North Carolina, the decorator crab Libinia dubia camouflages almost exclusively with the chemically noxious alga Dictyota menstrualis. By placing this alga on its carapace, the crab behaviorally sequesters the defensive chemicals of the plant and gains protection from omnivorous consumers. However, Dictyota is absent north of North Carolina, whereas Libinia occurs as far north as New England. Crabs from three northern locations where Dictyota is absent (Rhode Island, Connecticut, and New Jersey) camouflaged to match their environment, rather than selectively accumulating any one species. When D. menstrualis was offered to crabs from northern sites, they did not distinguish between it and other seaweeds for camouflage, whereas crabs from Alabama and two locations in North Carolina used D. menstrualis almost exclusively. In addition, in winter and spring, when Dictyota was seasonally absent in North Carolina, Libinia selectively camouflaged with the sun sponge Hymeniacidon heliophila, which was chemically unpalatable to local fishes. Thus, southern crabs were consistent specialists on chemically defended species for camouflage, while northern crabs were more generalized. The geographic shift in crab behavior away from specialization coincides with a reported decrease in both total predation pressure and the frequency of omnivorous consumers. These shifts in the nature and intensity of predation pressure may favor different camouflage strategies (generalist vs. specialist), contributing to the observed geographic differences in camouflage behavior.

  1. General paresis

    MedlinePlus

    General paresis of the insane; General paralysis of the insane; Paralytic dementia ... General paresis is one form of neurosyphilis . It usually occurs in people who have had untreated syphilis for many ...

  2. Geographic deaggregation of seismic hazard in the United States

    USGS Publications Warehouse

    Harmsen, S.; Frankel, A.

    2001-01-01

    The seismic hazard calculations for the 1996 national seismic hazard maps have been geographically deaggregated to assist in the understanding of the relative contributions of sources. These deaggregations are exhibited as maps with vertical bars whose heights are proportional to the contribution that each geographical cell makes to the ground-motion exceedance hazard. Bar colors correspond to average source magnitudes. We also extend the deaggregation analysis reported in Harmsen et al. (1999) to the western conterminous United States. In contrast to the central and eastern United States (CEUS); the influence of specific faults or characteristic events can be clearly identified. Geographic deaggregation for 0.2-sec and 1.0-sec pseudo spectral acceleration (SA) is performed for 10% probability of exceedance (PE) in 50 yr (475-yr mean return period) and 2% PE in 50 yr (2475-yr mean return period) for four western U.S. cities, Los Angeles, Salt Lake City, San Francisco, and Seattle, and for three central and eastern U.S. cities, Atlanta, Boston, and Saint Louis. In general, as the PE is lowered, the sources of hazard closer to the site dominate. Larger, more distant earthquakes contribute more significantly to hazard for 1.0-sec SA than for 0.2-sec SA. Additional maps of geographically deaggregated seismic hazard are available on the Internet for 120 cities in the conterminous United States (http://geohazards. cr.usgs.gov/eq/) for 1-sec SA and for 0.2-sec SA with a 2% PE in 50 yr. Examination of these maps of hazard contributions enables the investigator to determine the distance and azimuth to predominant sources, and their magnitudes. This information can be used to generate scenario earthquakes and corresponding time histories for seismic design and retrofit. Where fault density is lower than deaggregation cell dimensions, we can identify specific faults that contribute significantly to the seismic hazard at a given site. Detailed fault information enables

  3. Design Research of TIANDITU (Map Worl)-Based Geographic Information System for Travelling Service

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Zhang, H.; Wang, C.

    2014-04-01

    TIANDITU (Map World) is the public version of the National Platform for Common Geospatial Information Service, and the travelling channel is TIANDITU-based geographic information platform for travelling service. With the development of tourism, traditional ways for providing travelling information cannot meet the needs of travelers. As such, the travelling channel of TIANDITU focuses on providing travel information abundantly and precisely, which integrated the geographic information data of TIANDITU Version 2.0 and the authoritative information resources from China National Tourism Administration. Furthermore, spatial positioning, category and information query of various travelling information were offered for the public in the travelling channel. This research mainly involves three important parts: the system design, key technologies of the system design and application examples. Firstly, this paper introduced the design of TIANDITU-based geographic information system for travelling service, and the general and database design were described in detail. The designs for general, database and travelling service above should consider lots of factors which illustrated in the paper in order to guarantee the efficient service. The process of system construction, the content of geographic information for travelling and system functions of geographic information for travelling are also proposed via diagram in this part. Then several key technologies were discussed, including the travelling information integration for main node and among nodes, general architecture design and management system for travelling channel, web portals and system interface. From the perspective of main technologies, this part describes how TIANDITU travelling channel can realize various functions and reach the requirements from different users. Finally, three application examples about travelling information query were listed shortly. The functions and search results are shown clearly in this

  4. 33 CFR 169.10 - What geographic coordinates are used?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of 1983 (NAD 83), unless such geographic coordinates are expressly labeled NAD 83. Geographic coordinates without the NAD 83 reference may be plotted on maps or charts referenced to NAD 83 only after...

  5. Global Seismicity: Three New Maps Compiled with Geographic Information Systems

    NASA Technical Reports Server (NTRS)

    Lowman, Paul D., Jr.; Montgomery, Brian C.

    1996-01-01

    This paper presents three new maps of global seismicity compiled from NOAA digital data, covering the interval 1963-1998, with three different magnitude ranges (mb): greater than 3.5, less than 3.5, and all detectable magnitudes. A commercially available geographic information system (GIS) was used as the database manager. Epicenter locations were acquired from a CD-ROM supplied by the National Geophysical Data Center. A methodology is presented that can be followed by general users. The implications of the maps are discussed, including the limitations of conventional plate models, and the different tectonic behavior of continental vs. oceanic lithosphere. Several little-known areas of intraplate or passive margin seismicity are also discussed, possibly expressing horizontal compression generated by ridge push.

  6. On the mixing time of geographical threshold graphs

    SciTech Connect

    Bradonjic, Milan

    In this paper, we study the mixing time of random graphs generated by the geographical threshold graph (GTG) model, a generalization of random geometric graphs (RGG). In a GTG, nodes are distributed in a Euclidean space, and edges are assigned according to a threshold function involving the distance between nodes as well as randomly chosen node weights. The motivation for analyzing this model is that many real networks (e.g., wireless networks, the Internet, etc.) need to be studied by using a 'richer' stochastic model (which in this case includes both a distance between nodes and weights on the nodes). Wemore » specifically study the mixing times of random walks on 2-dimensional GTGs near the connectivity threshold. We provide a set of criteria on the distribution of vertex weights that guarantees that the mixing time is {Theta}(n log n).« less

  7. Geographic clusters in underimmunization and vaccine refusal.

    PubMed

    Lieu, Tracy A; Ray, G Thomas; Klein, Nicola P; Chung, Cindy; Kulldorff, Martin

    2015-02-01

    Parental refusal and delay of childhood vaccines has increased in recent years and is believed to cluster in some communities. Such clusters could pose public health risks and barriers to achieving immunization quality benchmarks. Our aims were to (1) describe geographic clusters of underimmunization and vaccine refusal, (2) compare clusters of underimmunization with different vaccines, and (3) evaluate whether vaccine refusal clusters may pose barriers to achieving high immunization rates. We analyzed electronic health records among children born between 2000 and 2011 with membership in Kaiser Permanente Northern California. The study population included 154,424 children in 13 counties with continuous membership from birth to 36 months of age. We used spatial scan statistics to identify clusters of underimmunization (having missed 1 or more vaccines by 36 months of age) and vaccine refusal (based on International Classification of Diseases, Ninth Revision, Clinical Modification codes). We identified 5 statistically significant clusters of underimmunization among children who turned 36 months old during 2010-2012. The underimmunization rate within clusters ranged from 18% to 23%, and the rate outside them was 11%. Children in the most statistically significant cluster had 1.58 (P < .001) times the rate of underimmunization as others. Underimmunization with measles, mumps, rubella vaccine and varicella vaccines clustered in similar geographic areas. Vaccine refusal also clustered, with rates of 5.5% to 13.5% within clusters, compared with 2.6% outside them. Underimmunization and vaccine refusal cluster geographically. Spatial scan statistics may be a useful tool to identify locations with challenges to achieving high immunization rates, which deserve focused intervention. Copyright © 2015 by the American Academy of Pediatrics.

  8. Geographic Information Systems and Web Page Development

    NASA Technical Reports Server (NTRS)

    Reynolds, Justin

    2004-01-01

    The Facilities Engineering and Architectural Branch is responsible for the design and maintenance of buildings, laboratories, and civil structures. In order to improve efficiency and quality, the FEAB has dedicated itself to establishing a data infrastructure based on Geographic Information Systems, GIS. The value of GIS was explained in an article dating back to 1980 entitled "Need for a Multipurpose Cadastre" which stated, "There is a critical need for a better land-information system in the United States to improve land-conveyance procedures, furnish a basis for equitable taxation, and provide much-needed information for resource management and environmental planning." Scientists and engineers both point to GIS as the solution. What is GIS? According to most text books, Geographic Information Systems is a class of software that stores, manages, and analyzes mapable features on, above, or below the surface of the earth. GIS software is basically database management software to the management of spatial data and information. Simply put, Geographic Information Systems manage, analyze, chart, graph, and map spatial information. GIS can be broken down into two main categories, urban GIS and natural resource GIS. Further still, natural resource GIS can be broken down into six sub-categories, agriculture, forestry, wildlife, catchment management, archaeology, and geology/mining. Agriculture GIS has several applications, such as agricultural capability analysis, land conservation, market analysis, or whole farming planning. Forestry GIs can be used for timber assessment and management, harvest scheduling and planning, environmental impact assessment, and pest management. GIS when used in wildlife applications enables the user to assess and manage habitats, identify and track endangered and rare species, and monitor impact assessment.

  9. Geolinde - a geographical online learning platform

    NASA Astrophysics Data System (ADS)

    Steinmüller, Max

    2017-04-01

    Starting about ten years ago during a classroom project on Africa, two colleagues and me started developing an educational platform with geographic content: www.geolinde.musin.de The basic concept was to collect and present a wide range of free educational materials, which could be used by teachers, students and anyone who is interested in geography as well. Soon we found out that producing units for our students also means working on age-appropriate texts on each topic. We made our learning units matching the curriculum for Bavarian 'Gymnasium' and are still working on the improvement of each single unit, especially on the basis of suggestions by our students and our teaching experience. The main advantage in teaching with units from geolinde is that the students work at their own speed, repeat topics, use the glossary or have a look at the skill pages. Everyone uses the wide range of materials in his own way to achieve the curricular goals. Many topics contain short online tests, so that the students can control their basic understanding. The teacher is set free for giving helpful advice, discussing special questions and to monitor the learning progress. After a certain time a question and answer session follows and puts the focus on major curricular goals. Until now www.geolinde.musin.de consists of several blended learning units: Africa, Europe, Climate, Climate Change, Plate tectonics,… It also contains thematic pages on many geographical skills, a glossary of more than one thousand geographic terms and last but not least a collection of approximately 23.000 photos of places of interest all around the world. All the many thousand web pages can be used freely (CC-BY-SA 4.0). The only limitation is www.geolinde.musin.de is available in German only.

  10. Urethroplasty: a geographic disparity in care.

    PubMed

    Burks, Frank N; Salmon, Scott A; Smith, Aaron C; Santucci, Richard A

    2012-06-01

    Urethroplasty is the gold standard for urethral strictures but its geographic prevalence throughout the United States is unknown. We analyzed where and how often urethroplasty was being performed in the United States compared to other treatment modalities for urethral stricture. De-identified case logs from the American Board of Urology were collected from certifying/recertifying urologists from 2004 to 2009. Results were categorized by ZIP codes to determine the geographic distribution. Case logs from 3,877 urologists (2,533 recertifying and 1,344 certifying) were reviewed including 1,836 urethroplasties, 13,080 urethrotomies and 19,564 urethral dilations. The proportion of urethroplasty varied widely among states (range 0% to 17%). The ratio of urethroplasty-to-urethrotomy/dilation also varied widely from state to state, but overall 1 urethroplasty was performed for every 17 urethrotomies or dilations performed. Certifying urologists were 3 times as likely to perform urethroplasty as recertifying urologists (12% vs 4%, respectively, p<0.05). Urethroplasties were performed more commonly in states with residency programs (mean 5% vs 3%). Some states reported no urethroplasties during the observation period (Vermont, North Dakota, South Dakota, Maine and West Virginia). To our knowledge this is the first report on the geographic distribution of urethroplasty for urethral stricture disease. There are large variations in the rates of urethroplasty performed throughout the United States, indicating a disparity of care, especially for those regions in which few or no urethroplasties were reported. This disparity may decrease with time as younger certifying urologists are performing 3 times as many urethroplasties as older recertifying urologists. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  11. [Geographic atrophy imaging using fundus autofluorescence method].

    PubMed

    Dolar-Szczasny, Joanna; Święch-Zubilewicz, Anna; Mackiewicz, Jerzy

    2015-01-01

    Geographic atrophy is a manifestation of the advanced age-related macular degeneration and form of irreversible atrophy of retinal pigment epithelium and photoreceptor layer. Early detection of changes and the ability to evaluate disease progression accurately constitute a key problem in diagnosis and treatment planning. Fundus autofluorescence is a relatively new imaging method considered nowadays to be the best in diagnosis and observing the natural or treatment-altered course of disease. High resolution images showing the 3D distribution of retinal pigment epithelium autofluorescence as lipofuscin index can be obtained owing to the launch of the confocal scanning laser ophthalmoscope.

  12. A multidimensional representation model of geographic features

    USGS Publications Warehouse

    Usery, E. Lynn; Timson, George; Coletti, Mark

    2016-01-28

    A multidimensional model of geographic features has been developed and implemented with data from The National Map of the U.S. Geological Survey. The model, programmed in C++ and implemented as a feature library, was tested with data from the National Hydrography Dataset demonstrating the capability to handle changes in feature attributes, such as increases in chlorine concentration in a stream, and feature geometry, such as the changing shoreline of barrier islands over time. Data can be entered directly, from a comma separated file, or features with attributes and relationships can be automatically populated in the model from data in the Spatial Data Transfer Standard format.

  13. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  14. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  15. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  16. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  17. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  18. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request an...

  19. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request an...

  20. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  1. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request an...

  2. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  3. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  4. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  5. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request an...

  6. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request an...

  7. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement under...

  8. Geographic Literacy and Moral Formation among University Students

    ERIC Educational Resources Information Center

    Bascom, Jonathan

    2011-01-01

    This study extends analysis of geographic literacy further by examining the relationship of geographic knowledge with the primary goal of geographic educators--cultivation of cultural understanding and moral sensitivity for global citizenry. The main aim is to examine contributors to moral formation during the university years based on a survey…

  9. 42 CFR § 512.105 - Geographic areas.

    Code of Federal Regulations, 2010 CFR

    2017-10-01

    ... (CONTINUED) HEALTH CARE INFRASTRUCTURE AND MODEL PROGRAMS EPISODE PAYMENT MODEL Episode Payment Model Participants § 512.105 Geographic areas. (a) The SHFFT model must be implemented in the same geographic areas as the CJR model as described under § 510.105 of the chapter. (b) The geographic areas for inclusion...

  10. Effect of Geographic Distance on Distance Education: An Empirical Study

    ERIC Educational Resources Information Center

    Luo, Heng; Robinson, Anthony C.; Detwiler, Jim

    2014-01-01

    This study investigates the effect of geographic distance on students' distance learning experience with the aim to provide tentative answers to a fundamental question--does geographic distance matter in distance education? Using educational outcome data collected from an online master's program in Geographic Information Systems, this study…

  11. Geographic Accessibility to Higher Education on the Island of Ireland

    ERIC Educational Resources Information Center

    Walsh, Sharon; Flannery, Darragh; Cullinan, John

    2015-01-01

    This paper presents, for the first time, comprehensive measures of geographic accessibility to higher education both within and between the Republic of Ireland and Northern Ireland. Using geographic information system techniques, we find high levels of geographic accessibility to higher education in both jurisdictions. However, when we…

  12. Introduction to the Complex Geospatial Web in Geographical Education

    ERIC Educational Resources Information Center

    Papadimitriou, Fivos

    2010-01-01

    The Geospatial Web is emerging in the geographical education landscape in all its complexity. How will geographers and educators react? What are the most important facets of this development? After reviewing the possible impacts on geographical education, it can be conjectured that the Geospatial Web will eventually replace the usual geographical…

  13. Experiments to Distribute Map Generalization Processes

    NASA Astrophysics Data System (ADS)

    Berli, Justin; Touya, Guillaume; Lokhat, Imran; Regnauld, Nicolas

    2018-05-01

    Automatic map generalization requires the use of computationally intensive processes often unable to deal with large datasets. Distributing the generalization process is the only way to make them scalable and usable in practice. But map generalization is a highly contextual process, and the surroundings of a generalized map feature needs to be known to generalize the feature, which is a problem as distribution might partition the dataset and parallelize the processing of each part. This paper proposes experiments to evaluate the past propositions to distribute map generalization, and to identify the main remaining issues. The past propositions to distribute map generalization are first discussed, and then the experiment hypotheses and apparatus are described. The experiments confirmed that regular partitioning was the quickest strategy, but also the less effective in taking context into account. The geographical partitioning, though less effective for now, is quite promising regarding the quality of the results as it better integrates the geographical context.

  14. Acquiring geographical data with web harvesting

    NASA Astrophysics Data System (ADS)

    Dramowicz, K.

    2016-04-01

    Many websites contain very attractive and up to date geographical information. This information can be extracted, stored, analyzed and mapped using web harvesting techniques. Poorly organized data from websites are transformed with web harvesting into a more structured format, which can be stored in a database and analyzed. Almost 25% of web traffic is related to web harvesting, mostly while using search engines. This paper presents how to harvest geographic information from web documents using the free tool called the Beautiful Soup, one of the most commonly used Python libraries for pulling data from HTML and XML files. It is a relatively easy task to process one static HTML table. The more challenging task is to extract and save information from tables located in multiple and poorly organized websites. Legal and ethical aspects of web harvesting are discussed as well. The paper demonstrates two case studies. The first one shows how to extract various types of information about the Good Country Index from the multiple web pages, load it into one attribute table and map the results. The second case study shows how script tools and GIS can be used to extract information from one hundred thirty six websites about Nova Scotia wines. In a little more than three minutes a database containing one hundred and six liquor stores selling these wines is created. Then the availability and spatial distribution of various types of wines (by grape types, by wineries, and by liquor stores) are mapped and analyzed.

  15. Semi-Supervised Geographical Feature Detection

    NASA Astrophysics Data System (ADS)

    Yu, H.; Yu, L.; Kuo, K. S.

    2016-12-01

    Extraction and tracking geographical features is a fundamental requirement in many geoscience fields. However, this operation has become an increasingly challenging task for domain scientists when tackling a large amount of geoscience data. Although domain scientists may have a relatively clear definition of features, it is difficult to capture the presence of features in an accurate and efficient fashion. We propose a semi-supervised approach to address large geographical feature detection. Our approach has two main components. First, we represent a heterogeneous geoscience data in a unified high-dimensional space, which can facilitate us to evaluate the similarity of data points with respect to geolocation, time, and variable values. We characterize the data from these measures, and use a set of hash functions to parameterize the initial knowledge of the data. Second, for any user query, our approach can automatically extract the initial results based on the hash functions. To improve the accuracy of querying, our approach provides a visualization interface to display the querying results and allow users to interactively explore and refine them. The user feedback will be used to enhance our knowledge base in an iterative manner. In our implementation, we use high-performance computing techniques to accelerate the construction of hash functions. Our design facilitates a parallelization scheme for feature detection and extraction, which is a traditionally challenging problem for large-scale data. We evaluate our approach and demonstrate the effectiveness using both synthetic and real world datasets.

  16. Using volunteered geographic information to visualize ...

    EPA Pesticide Factsheets

    Volunteered geographic information (VGI), specifically geotagged photographs available from social media platforms, is a promising technology that can be utilized to identify public values for ecosystem goods and services in a defined geographic area. VGI can help researchers indirectly survey and report on the values and preferences of communities involved in restoration and revitalization projects. We are using geotagged images from three social media platforms: Flickr, Instagram, and Panaramio. Images are obtained for the neighborhoods to the St. Louis River in the Duluth, MN and analyzed along several dimensions including the spatial distribution of images from each platform and the types and frequencies of social values and ecosystem service depicted. This study will demonstrate a method for translating the values of ecosystem goods and services as captured in social media into spatially-explicit data. Study outcomes are the incorporation of social media-derived indicators of ecosystems services into City of Duluth’s Comprehensive Planning and community revitalization efforts, habitat restoration in a Great Lakes Area of Concern, and the USEPA’s Office of Research and Development Sustainable and Healthy Community research. Not applicable

  17. Geographic Gossip: Efficient Averaging for Sensor Networks

    NASA Astrophysics Data System (ADS)

    Dimakis, Alexandros D. G.; Sarwate, Anand D.; Wainwright, Martin J.

    Gossip algorithms for distributed computation are attractive due to their simplicity, distributed nature, and robustness in noisy and uncertain environments. However, using standard gossip algorithms can lead to a significant waste in energy by repeatedly recirculating redundant information. For realistic sensor network model topologies like grids and random geometric graphs, the inefficiency of gossip schemes is related to the slow mixing times of random walks on the communication graph. We propose and analyze an alternative gossiping scheme that exploits geographic information. By utilizing geographic routing combined with a simple resampling method, we demonstrate substantial gains over previously proposed gossip protocols. For regular graphs such as the ring or grid, our algorithm improves standard gossip by factors of $n$ and $\\sqrt{n}$ respectively. For the more challenging case of random geometric graphs, our algorithm computes the true average to accuracy $\\epsilon$ using $O(\\frac{n^{1.5}}{\\sqrt{\\log n}} \\log \\epsilon^{-1})$ radio transmissions, which yields a $\\sqrt{\\frac{n}{\\log n}}$ factor improvement over standard gossip algorithms. We illustrate these theoretical results with experimental comparisons between our algorithm and standard methods as applied to various classes of random fields.

  18. Experimental effects of climate messages vary geographically

    NASA Astrophysics Data System (ADS)

    Zhang, Baobao; van der Linden, Sander; Mildenberger, Matto; Marlon, Jennifer R.; Howe, Peter D.; Leiserowitz, Anthony

    2018-05-01

    Social science scholars routinely evaluate the efficacy of diverse climate frames using local convenience or nationally representative samples1-5. For example, previous research has focused on communicating the scientific consensus on climate change, which has been identified as a `gateway' cognition to other key beliefs about the issue6-9. Importantly, although these efforts reveal average public responsiveness to particular climate frames, they do not describe variation in message effectiveness at the spatial and political scales relevant for climate policymaking. Here we use a small-area estimation method to map geographical variation in public responsiveness to information about the scientific consensus as part of a large-scale randomized national experiment (n = 6,301). Our survey experiment finds that, on average, public perception of the consensus increases by 16 percentage points after message exposure. However, substantial spatial variation exists across the United States at state and local scales. Crucially, responsiveness is highest in more conservative parts of the country, leading to national convergence in perceptions of the climate science consensus across diverse political geographies. These findings not only advance a geographical understanding of how the public engages with information about scientific agreement, but will also prove useful for policymakers, practitioners and scientists engaged in climate change mitigation and adaptation.

  19. A Method for Analyzing Volunteered Geographic Information ...

    EPA Pesticide Factsheets

    Volunteered geographic information (VGI) can be used to identify public valuation of ecosystem services in a defined geographic area using photos as a representation of lived experiences. This method can help researchers better survey and report on the values and preferences of stakeholders involved in rehabilitation and revitalization projects. Current research utilizes VGI in the form of geotagged social media photos from three platforms: Flickr, Instagram, and Panaramio. Social media photos have been obtained for the neighborhoods next to the St. Louis River in Duluth, Minnesota, and are being analyzed along several dimensions. These dimensions include the spatial distribution of each platform, the characteristics of the physical environment portrayed in the photos, and finally, the ecosystem service depicted. In this poster, we focus on the photos from the Irving and Fairmount neighborhoods of Duluth, MN to demonstrate the method at the neighborhood scale. This study demonstrates a method for translating the values expressed in social media photos into ecosystem services and spatially-explicit data to be used in multiple settings, including the City of Duluth’s Comprehensive Planning and community revitalization efforts, habitat restoration in a Great Lakes Area of Concern, and the USEPA’s Office of Research and Development. This poster will demonstrate a method for translating values expressed in social media photos into ecosystem services and spatially

  20. Global Health, Geographical Contingency, and Contingent Geographies

    PubMed Central

    Herrick, Clare

    2016-01-01

    Health geography has emerged from under the “shadow of the medical” to become one of the most vibrant of all the subdisciplines. Yet, this success has also meant that health research has become increasingly siloed within this subdisciplinary domain. As this article explores, this represents a potential lost opportunity with regard to the study of global health, which has instead come to be dominated by anthropology and political science. Chief among the former's concerns are exploring the gap between the programmatic intentions of global health and the unintended or unanticipated consequences of their deployment. This article asserts that recent work on contingency within geography offers significant conceptual potential for examining this gap. It therefore uses the example of alcohol taxation in Botswana, an emergent global health target and tool, to explore how geographical contingency and the emergent, contingent geographies that result might help counter the prevailing tendency for geography to be side-stepped within critical studies of global health. At the very least, then, this intervention aims to encourage reflection by geographers on how to make explicit the all-too-often implicit links between their research and global health debates located outside the discipline. PMID:27611662

  1. Geographic Wormhole Detection in Wireless Sensor Networks

    PubMed Central

    Sookhak, Mehdi; Akhundzada, Adnan; Sookhak, Alireza; Eslaminejad, Mohammadreza; Gani, Abdullah; Khurram Khan, Muhammad; Li, Xiong; Wang, Xiaomin

    2015-01-01

    Wireless sensor networks (WSNs) are ubiquitous and pervasive, and therefore; highly susceptible to a number of security attacks. Denial of Service (DoS) attack is considered the most dominant and a major threat to WSNs. Moreover, the wormhole attack represents one of the potential forms of the Denial of Service (DoS) attack. Besides, crafting the wormhole attack is comparatively simple; though, its detection is nontrivial. On the contrary, the extant wormhole defense methods need both specialized hardware and strong assumptions to defend against static and dynamic wormhole attack. The ensuing paper introduces a novel scheme to detect wormhole attacks in a geographic routing protocol (DWGRP). The main contribution of this paper is to detect malicious nodes and select the best and the most reliable neighbors based on pairwise key pre-distribution technique and the beacon packet. Moreover, this novel technique is not subject to any specific assumption, requirement, or specialized hardware, such as a precise synchronized clock. The proposed detection method is validated by comparisons with several related techniques in the literature, such as Received Signal Strength (RSS), Authentication of Nodes Scheme (ANS), Wormhole Detection uses Hound Packet (WHOP), and Wormhole Detection with Neighborhood Information (WDI) using the NS-2 simulator. The analysis of the simulations shows promising results with low False Detection Rate (FDR) in the geographic routing protocols. PMID:25602616

  2. Geographically weighted regression model on poverty indicator

    NASA Astrophysics Data System (ADS)

    Slamet, I.; Nugroho, N. F. T. A.; Muslich

    2017-12-01

    In this research, we applied geographically weighted regression (GWR) for analyzing the poverty in Central Java. We consider Gaussian Kernel as weighted function. The GWR uses the diagonal matrix resulted from calculating kernel Gaussian function as a weighted function in the regression model. The kernel weights is used to handle spatial effects on the data so that a model can be obtained for each location. The purpose of this paper is to model of poverty percentage data in Central Java province using GWR with Gaussian kernel weighted function and to determine the influencing factors in each regency/city in Central Java province. Based on the research, we obtained geographically weighted regression model with Gaussian kernel weighted function on poverty percentage data in Central Java province. We found that percentage of population working as farmers, population growth rate, percentage of households with regular sanitation, and BPJS beneficiaries are the variables that affect the percentage of poverty in Central Java province. In this research, we found the determination coefficient R2 are 68.64%. There are two categories of district which are influenced by different of significance factors.

  3. Workload management and geographic disorientation in aviation incidents: A review of the ASRS data base

    NASA Technical Reports Server (NTRS)

    Williams, Henry P.; Tham, Mingpo; Wickens, Christopher D.

    1993-01-01

    NASA's Aviation Safety Reporting System (ASRS) incident reports are reviewed in two related areas: pilots' failures to appropriately manage tasks, and breakdowns in geographic orientation. Examination of 51 relevant reports on task management breakdowns revealed that altitude busts and inappropriate runway usee were the most frequently reported consequences. Task management breakdowns appeared to occur at all levels of expertise, and prominent causal factors were related to breakdowns in crew communications, over-involvement with the flight management system and, for small (general aviation) aircraft, preoccupation with weather. Analysis of the 83 cases of geographic disorientation suggested that these too occurred at all levels of pilot experience. With regard to causal factors, a majority was related to poor cockpit resource management, in which inattention led to a loss of geographic awareness. Other leading causes were related to poor weather and poor decision making. The potential of the ASRS database for contributing to research and design issues is addressed.

  4. Geographic variation in the relationship between body mass index and the built environment.

    PubMed

    Adachi-Mejia, Anna M; Lee, Chanam; Lee, Chunkuen; Carlos, Heather A; Saelens, Brian E; Berke, Ethan M; Doescher, Mark P

    2017-07-01

    Studies examining associations between weight status and neighborhood built environment (BE) have shown inconsistent results and have generally focused on urban settings. However, many Americans do not live in metropolitan areas and BE impacts may be different outside of metropolitan areas. We sought to examine whether the relationship between body mass index (BMI) and neighborhood BE exists and varies by geographic region across small towns in the United States. We conducted telephone surveys with 2156 adults and geographic information systems data in nine towns located within three geographic regions (Northeast, Texas, Washington) in 2011 and 2012. Multiple regression models examined the relationship between individual BMI and BE measures. Most physical activity variables were significantly associated with lower BMI in all geographic regions. We saw variation across geographic region in the relationship between characteristics of the BE variables and BMI. Some perceived and objectively-measured characteristics of the BE were significantly associated with adult BMI, but significant relationships varied by geographic region. For example, in the Northeast, perceived attractiveness of the neighborhood as a reason for why they chose to live there was associated with lower BMI; in Texas, the perceived presence of a fast food restaurant was negatively associated with BMI; in Washington, perceived presence of trees along the streets was associated with lower BMI. Our findings suggest that regional variation plays a role in the relationship between adult BMI and BE characteristics in small towns. Regardless of geographic location, interventions should encourage utilitarian walking and other forms of physical activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Correlates and geographic patterns of knowledge that physical activity decreases cancer risk.

    PubMed

    Ramírez, A Susana; Finney Rutten, Lila J; Vanderpool, Robin C; Moser, Richard P; Hesse, Bradford W

    2013-04-01

    While many lifestyle-related cancer risk factors including tobacco use, poor diet, and sun exposure are well recognized by the general public, the role of physical activity in decreasing cancer risk is less recognized. Studies have demonstrated gender-, race/ethnicity-, and age-based disparities in cancer risk factor knowledge; however, beliefs and geographic factors that may be related to knowledge are under-examined. In this study, we analyzed data from the 2008 Health Information National Trends Survey to determine correlates of knowledge of the relationship between physical activity and reduced cancer risk in the adult US population. We generated geographic information system maps to examine the geographic distribution of this knowledge. Results revealed that there is confusion among US adults about the relationship between physical activity and cancer risk: Respondents who believed that cancer is not preventable had significantly lower odds of knowing that physical activity reduces cancer risk (p < .001) whereas respondents who believed that cancer is caused by one's behavior had almost two times the odds of knowing that physical activity reduces cancer risk (p < .001). Those who were aware of current physical activity guidelines were also significantly more likely to know that physical activity reduces cancer risk (p < .01). Observed geographic variability in knowledge was consistent with geographic trends in obesity and physical inactivity. Correlates of cancer risk factor knowledge point to opportunities for targeted interventions.

  6. Remote sensing research in geographic education: An alternative view

    NASA Technical Reports Server (NTRS)

    Wilson, H.; Cary, T. K.; Goward, S. N.

    1981-01-01

    It is noted that within many geography departments remote sensing is viewed as a mere technique a student should learn in order to carry out true geographic research. This view inhibits both students and faculty from investigation of remotely sensed data as a new source of geographic knowledge that may alter our understanding of the Earth. The tendency is for geographers to accept these new data and analysis techniques from engineers and mathematicians without questioning the accompanying premises. This black-box approach hinders geographic applications of the new remotely sensed data and limits the geographer's contribution to further development of remote sensing observation systems. It is suggested that geographers contribute to the development of remote sensing through pursuit of basic research. This research can be encouraged, particularly among students, by demonstrating the links between geographic theory and remotely sensed observations, encouraging a healthy skepticism concerning the current understanding of these data.

  7. Integrating Geographic Information Systems (GIS) Applications into Business Courses Using Online Business Geographics Modules

    ERIC Educational Resources Information Center

    Miller, Fred; Mangold, W. Glynn; Holmes, Terry

    2006-01-01

    Although the value of geographic information systems (GIS) technologies is recognized by practitioners and educators alike, GIS instruction has yet to make significant inroads into business curricula. In this article, the authors discuss the constraints of integrating GIS tools into business education. They develop a prototype module for…

  8. Geographic Information Systems and Web Page Development

    NASA Technical Reports Server (NTRS)

    Reynolds, Justin

    2004-01-01

    The Facilities Engineering and Architectural Branch is responsible for the design and maintenance of buildings, laboratories, and civil structures. In order to improve efficiency and quality, the FEAB has dedicated itself to establishing a data infrastructure based on Geographic Information Systems, GIs. The value of GIS was explained in an article dating back to 1980 entitled "Need for a Multipurpose Cadastre which stated, "There is a critical need for a better land-information system in the United States to improve land-conveyance procedures, furnish a basis for equitable taxation, and provide much-needed information for resource management and environmental planning." Scientists and engineers both point to GIS as the solution. What is GIS? According to most text books, Geographic Information Systems is a class of software that stores, manages, and analyzes mapable features on, above, or below the surface of the earth. GIS software is basically database management software to the management of spatial data and information. Simply put, Geographic Information Systems manage, analyze, chart, graph, and map spatial information. At the outset, I was given goals and expectations from my branch and from my mentor with regards to the further implementation of GIs. Those goals are as follows: (1) Continue the development of GIS for the underground structures. (2) Extract and export annotated data from AutoCAD drawing files and construct a database (to serve as a prototype for future work). (3) Examine existing underground record drawings to determine existing and non-existing underground tanks. Once this data was collected and analyzed, I set out on the task of creating a user-friendly database that could be assessed by all members of the branch. It was important that the database be built using programs that most employees already possess, ruling out most AutoCAD-based viewers. Therefore, I set out to create an Access database that translated onto the web using Internet

  9. Racial and geographic differences in fish consumption

    PubMed Central

    Le, A.; Judd, S.; Frankel, M.R.; Ard, J.; Newby, P.K.; Howard, V.J.

    2011-01-01

    Background: Omega-3 fatty acids from fish have been shown to have favorable effects on platelet aggregation, blood pressure, lipid profile, endothelial function, and ischemic stroke risk, but there are limited data on racial and geographic differences in fish consumption. Methods: Reasons for Geographic and Racial Differences in Stroke (REGARDS) is a national cohort study that recruited 30,239 participants age ≥45 years with oversampling from the southeastern Stroke Belt and Buckle and African Americans (AAs). Centralized phone interviewers obtained medical histories and in-home examiners measured weight and height. Dietary data for this cross-sectional analysis were collected using the self-administered Block98 Food Frequency Questionnaire (FFQ). Adequate intake of nonfried fish was defined as consumption of ≥2 servings per week based on American Heart Association guidelines. After excluding the top and bottom 1% of total energy intake and individuals who did not answer 85% or more of questions on the FFQ, the analysis included 21,675 participants. Results: Only 5,022 (23%) participants consumed ≥2 servings per week of nonfried fish. In multivariable analysis, factors associated with inadequate intake of nonfried fish included living in the Stroke Belt (vs non-Belt) (odds ratio [OR] 0.83, 95% confidence interval [CI] 0.77–0.90) and living in the Stroke Buckle (vs non-Belt) (OR 0.89, 95% CI 0.81–0.98); factors associated with ≥2 servings per week of fried fish included being AA (vs white) (OR 3.59, 95% CI 3.19–4.04), living in the Stroke Belt (vs non-Belt) (OR 1.32, 95% CI 1.17–1.50), and living in the Stroke Buckle (vs non-Belt) (OR 1.17, 95% CI 1.00–1.36). Conclusions: Differential consumption of fish may contribute to the racial and geographic disparities in stroke. PMID:21178096

  10. Geographic Variance of Cost Associated With Hysterectomy.

    PubMed

    Sheyn, David; Mahajan, Sangeeta; Billow, Megan; Fleary, Alexandra; Hayashi, Emi; El-Nashar, Sherif A

    2017-05-01

    To estimate whether the cost of hysterectomy varies by geographic region. This was a cross-sectional, population-based study using the 2013 Healthcare Cost and Utilization Project National Inpatient Sample of women older than 18 years undergoing inpatient hysterectomy for benign conditions. Hospital charges obtained from the National Inpatient Sample database were converted to actual costs using cost-to-charge ratios provided by the Healthcare Cost and Utilization Project. Multivariate regression was used to assess the effects that demographic factors, concomitant procedures, diagnoses, and geographic region have on hysterectomy cost above the median. Women who underwent hysterectomy for benign conditions were identified (N=38,414). The median cost of hysterectomy was $13,981 (interquartile range $9,075-29,770). The mid-Atlantic region had the lowest median cost of $9,661 (interquartile range $6,243-15,335) and the Pacific region had the highest median cost, $22,534 (interquartile range $15,380-33,797). Compared with the mid-Atlantic region, the Pacific (adjusted odds ratio [OR] 10.43, 95% confidence interval [CI] 9.44-11.45), South Atlantic (adjusted OR 5.39, 95% CI 4.95-5.86), and South Central (adjusted OR 2.40, 95% CI 2.21-2.62) regions were associated with the highest probability of costs above the median. All concomitant procedures were associated with an increased cost with the exception of bilateral salpingectomy (adjusted OR 1.03, 95% CI 0.95-1.12). Compared with vaginal hysterectomy, laparoscopic and robotic modes of hysterectomy were associated with higher probabilities of increased costs (adjusted OR 2.86, 95% CI 2.61-3.15 and adjusted OR 5.66, 95% CI 5.11-6.26, respectively). Abdominal hysterectomy was not associated with a statistically significant increase in cost compared with vaginal hysterectomy (adjusted OR 1.01, 95% CI 0.91-1.09). The cost of hysterectomy varies significantly with geographic region after adjusting for confounders.

  11. Correlation Assessment of Climate and Geographic Distribution of Tuberculosis Using Geographical Information System (GIS).

    PubMed

    Beiranvand, Reza; Karimi, Asrin; Delpisheh, Ali; Sayehmiri, Kourosh; Soleimani, Samira; Ghalavandi, Shahnaz

    2016-01-01

    Tuberculosis (TB) spread pattern is influenced by geographic and social factors. Nowadays Geographic Information System (GIS) is one of the most important epidemiological instrumentation identifying high-risk population groups and geographic areas of TB. The aim of this study was to determine the correlation between climate and geographic distribution of TB in Khuzestan Province using GIS during 2005-2012. Through an ecological study, all 6363 patients with definite diagnosis of TB from 2005 until the end of September 2012 in Khuzestan Province, southern Iran were diagnosed. Data were recorded using TB- Register software. Tuberculosis incidence based on the climate and the average of annual rain was evaluated using GIS. Data were analyzed through SPSS software. Independent t-test, ANOVA, Linear regression, Pearson and Eta correlation coefficient with a significance level of less than 5% were used for the statistical analysis. The TB incidence was different in various geographic conditions. The highest mean of TB cumulative incidence rate was observed in extra dry areas (P= 0.017). There was a significant inverse correlation between annual rain rate and TB incidence rate (R= -0.45, P= 0.001). The lowest TB incidence rate (0-100 cases per 100,000) was in areas with the average of annual rain more than 1000 mm (P= 0.003). The risk of TB has a strong relationship with climate and the average of annual rain, so that the risk of TB in areas with low annual rainfall and extra dry climate is more than other regions. Services and special cares to high-risk regions of TB are recommended.

  12. Geographic Visualization of Power-Grid Dynamics

    SciTech Connect

    Sukumar, Sreenivas R.

    2015-06-18

    The visualization enables the simulation analyst to see changes in the frequency through time and space. With this technology, the analyst has a bird's eye view of the frequency at loads and generators as the simulated power system responds to the loss of a generator, spikes in load, and other contingencies. The significance of a contingency to the operation of an electrical power system depends critically on how the resulting tansients evolve in time and space. Consequently, these dynamic events can only be understood when seen in their proper geographic context. this understanding is indispensable to engineers working on themore » next generation of distributed sensing and control systems for the smart grid. By making possible a natural and intuitive presentation of dynamic behavior, our new visualization technology is a situational-awareness tool for power-system engineers.« less

  13. Comprehensive monitoring for heterogeneous geographically distributed storage

    DOE PAGES

    Ratnikova, Natalia; Karavakis, E.; Lammel, S.; ...

    2015-12-23

    Storage capacity at CMS Tier-1 and Tier-2 sites reached over 100 Petabytes in 2014, and will be substantially increased during Run 2 data taking. The allocation of storage for the individual users analysis data, which is not accounted as a centrally managed storage space, will be increased to up to 40%. For comprehensive tracking and monitoring of the storage utilization across all participating sites, CMS developed a space monitoring system, which provides a central view of the geographically dispersed heterogeneous storage systems. The first prototype was deployed at pilot sites in summer 2014, and has been substantially reworked since then.more » In this study, we discuss the functionality and our experience of system deployment and operation on the full CMS scale.« less

  14. Geographic analysis of shigellosis in Vietnam.

    PubMed

    Kim, Deok Ryun; Ali, Mohammad; Thiem, Vu Dinh; Park, Jin-Kyung; von Seidlein, Lorenz; Clemens, John

    2008-12-01

    Geographic and ecological analysis may provide investigators useful ecological information for the control of shigellosis. This paper provides distribution of individual Shigella species in space, and ecological covariates for shigellosis in Nha Trang, Vietnam. Data on shigellosis in neighborhoods were used to identify ecological covariates. A Bayesian hierarchical model was used to obtain joint posterior distribution of model parameters and to construct smoothed risk maps for shigellosis. Neighborhoods with a high proportion of worshippers of traditional religion, close proximity to hospital, or close proximity to the river had increased risk for shigellosis. The ecological covariates associated with Shigella flexneri differed from the covariates for Shigella sonnei. In contrast the spatial distribution of the two species was similar. The disease maps can help identify high-risk areas of shigellosis that can be targeted for interventions. This approach may be useful for the selection of populations and the analysis of vaccine trials.

  15. Geographical Education and Society. Papers Presented at Commission on Geographical Education International Geographical Union (Sitges, Spain, August 25-31, 1986).

    ERIC Educational Resources Information Center

    Hernando, Agustin, Ed.

    Educational discourse is totally completely imbued with the values that affect the societies to which individuals belong. Those in the field of geographical education must examine those values in order to determine what type of geographical education is best for each society. The following papers contribute to this knowledge: "Presentation"…

  16. Stennis Space Center Environmental Geographic Information System

    NASA Technical Reports Server (NTRS)

    Lovely, Janette; Cohan, Tyrus

    2000-01-01

    As NASA's lead center for rocket propulsion testing, the John C. Stennis Space Center (SSC) monitors and assesses the off-site impacts of such testing through its Environmental Office (SSC-EO) using acoustical models and ancillary data. The SSC-EO has developed a geographical database, called the SSC Environmental Geographic Information System (SSC-EGIS), that covers an eight-county area bordering the NASA facility. Through the SSC-EGIS, the Enivronmental Office inventories, assesses, and manages the nearly 139,000 acres that comprise Stennis Space Center and its surrounding acoustical buffer zone. The SSC-EGIS contains in-house data as well as a wide range of data obtained from outside sources, including private agencies and local, county, state, and U.S. government agencies. The database comprises cadastral/geodetic, hydrology, infrastructure, geo-political, physical geography, and socio-economic vector and raster layers. The imagery contained in the database is varied, including low-resolution imagery, such as Landsat TM and SPOT; high-resolution imagery, such as IKONOS and AVIRIS; and aerial photographs. The SSC-EGIS has been an integral part of several major projects and the model upon which similar EGIS's will be developed for other NASA facilities. The Corps of Engineers utilized the SSC-EGIS in a plan to establish wetland mitigation sites within the SSC buffer zone. Mississippi State University employed the SSC-EGIS in a preliminary study to evaluate public access points within the buffer zone. The SSC-EO has also expressly used the SSC-EGIS to assess noise pollution modeling, land management/wetland mitigation assessment, environmental hazards mapping, and protected areas mapping for archaeological sites and for threatened and endangered species habitats. The SSC-EO has several active and planned projects that will also make use of the SSC-EGIS during this and the coming fiscal year.

  17. Modelling Ecuador's rainfall distribution according to geographical characteristics.

    NASA Astrophysics Data System (ADS)

    Tobar, Vladimiro; Wyseure, Guido

    2017-04-01

    It is known that rainfall is affected by terrain characteristics and some studies had focussed on its distribution over complex terrain. Ecuador's temporal and spatial rainfall distribution is affected by its location on the ITCZ, the marine currents in the Pacific, the Amazon rainforest, and the Andes mountain range. Although all these factors are important, we think that the latter one may hold a key for modelling spatial and temporal distribution of rainfall. The study considered 30 years of monthly data from 319 rainfall stations having at least 10 years of data available. The relatively low density of stations and their location in accessible sites near to main roads or rivers, leave large and important areas ungauged, making it not appropriate to rely on traditional interpolation techniques to estimate regional rainfall for water balance. The aim of this research was to come up with a useful model for seasonal rainfall distribution in Ecuador based on geographical characteristics to allow its spatial generalization. The target for modelling was the seasonal rainfall, characterized by nine percentiles for each one of the 12 months of the year that results in 108 response variables, later on reduced to four principal components comprising 94% of the total variability. Predictor variables for the model were: geographic coordinates, elevation, main wind effects from the Amazon and Coast, Valley and Hill indexes, and average and maximum elevation above the selected rainfall station to the east and to the west, for each one of 18 directions (50-135°, by 5°) adding up to 79 predictors. A multiple linear regression model by the Elastic-net algorithm with cross-validation was applied for each one of the PC as response to select the most important ones from the 79 predictor variables. The Elastic-net algorithm deals well with collinearity problems, while allowing variable selection in a blended approach between the Ridge and Lasso regression. The model fitting

  18. Geographic Information Systems to Assess External Validity in Randomized Trials.

    PubMed

    Savoca, Margaret R; Ludwig, David A; Jones, Stedman T; Jason Clodfelter, K; Sloop, Joseph B; Bollhalter, Linda Y; Bertoni, Alain G

    2017-08-01

    To support claims that RCTs can reduce health disparities (i.e., are translational), it is imperative that methodologies exist to evaluate the tenability of external validity in RCTs when probabilistic sampling of participants is not employed. Typically, attempts at establishing post hoc external validity are limited to a few comparisons across convenience variables, which must be available in both sample and population. A Type 2 diabetes RCT was used as an example of a method that uses a geographic information system to assess external validity in the absence of a priori probabilistic community-wide diabetes risk sampling strategy. A geographic information system, 2009-2013 county death certificate records, and 2013-2014 electronic medical records were used to identify community-wide diabetes prevalence. Color-coded diabetes density maps provided visual representation of these densities. Chi-square goodness of fit statistic/analysis tested the degree to which distribution of RCT participants varied across density classes compared to what would be expected, given simple random sampling of the county population. Analyses were conducted in 2016. Diabetes prevalence areas as represented by death certificate and electronic medical records were distributed similarly. The simple random sample model was not a good fit for death certificate record (chi-square, 17.63; p=0.0001) and electronic medical record data (chi-square, 28.92; p<0.0001). Generally, RCT participants were oversampled in high-diabetes density areas. Location is a highly reliable "principal variable" associated with health disparities. It serves as a directly measurable proxy for high-risk underserved communities, thus offering an effective and practical approach for examining external validity of RCTs. Copyright © 2017 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  19. The NASA John C. Stennis Environmental Geographic Information System

    NASA Technical Reports Server (NTRS)

    Cohan, Tyrus; Grant, Kerry

    2002-01-01

    In addition to the Environmental Geographic Information System (EGIS) presentation, we will present two live demonstrations of a portion of the work being performed in support of environmental operations onsite and NASA-wide. These live demonstrations will showcase the NASA EGIS database through working versions of two software packages available from Environmental Systems Research Institute, Inc. (ESRI, Inc.): ArcIMS 3.0 and either ArcView 3.2a or ArcGIS 8.0.2. Using a standard web browser, the ArcIMS demo will allow users to access a project file containing several data layers found in the EGIS database. ArcIMS is configured so that a single computer can be used as the data server and as the user interface, which allows for maximum Internet security because the computer being used will not actually be connected to the World Wide Web. Further, being independent of the Internet, the demo will run at an increased speed. This demo will include several data layers that are specific to Stennis Space Center. The EGIS database demo is a representative portion of the entire EGIS project sent to NASA Headquarters last year. This demo contains data files that are readily available at various government agency Web sites for download. Although these files contain roads, rails, and other infrastructure details, they are generalized and at a small enough scale that they provide only a general idea of each NASA center's surroundings rather than specific details of the area.

  20. Geographic disparities in colorectal cancer survival

    PubMed Central

    Henry, Kevin A; Niu, Xiaoling; Boscoe, Francis P

    2009-01-01

    Background Examining geographic variation in cancer patient survival can help identify important prognostic factors that are linked by geography and generate hypotheses about the underlying causes of survival disparities. In this study, we apply a recently developed spatial scan statistic method, designed for time-to-event data, to determine whether colorectal cancer (CRC) patient survival varies by place of residence after adjusting survival times for several prognostic factors. Methods Using data from a population-based, statewide cancer registry, we examined a cohort of 25,040 men and women from New Jersey who were newly diagnosed with local or regional stage colorectal cancer from 1996 through 2003 and followed to the end of 2006. Survival times were adjusted for significant prognostic factors (sex, age, stage at diagnosis, race/ethnicity and census tract socioeconomic deprivation) and evaluated using a spatial scan statistic to identify places where CRC survival was significantly longer or shorter than the statewide experience. Results Age, sex and stage adjusted survival times revealed several areas in the northern part of the state where CRC survival was significantly different than expected. The shortest and longest survival areas had an adjusted 5-year survival rate of 73.1% (95% CI 71.5, 74.9) and 88.3% (95% CI 85.4, 91.3) respectively, compared with the state average of 80.0% (95% CI 79.4, 80.5). Analysis of survival times adjusted for age, sex and stage as well as race/ethnicity and area socioeconomic deprivation attenuated the risk of death from CRC in several areas, but survival disparities persisted. Conclusion The results suggest that in areas where additional adjustments for race/ethnicity and area socioeconomic deprivation changed the geographic survival patterns and reduced the risk of death from CRC, the adjustment factors may be contributing causes of the disparities. Further studies should focus on specific and modifiable individual and

  1. A review of geographic variation and Geographic Information Systems (GIS) applications in prescription drug use research.

    PubMed

    Wangia, Victoria; Shireman, Theresa I

    2013-01-01

    While understanding geography's role in healthcare has been an area of research for over 40 years, the application of geography-based analyses to prescription medication use is limited. The body of literature was reviewed to assess the current state of such studies to demonstrate the scale and scope of projects in order to highlight potential research opportunities. To review systematically how researchers have applied geography-based analyses to medication use data. Empiric, English language research articles were identified through PubMed and bibliographies. Original research articles were independently reviewed as to the medications or classes studied, data sources, measures of medication exposure, geographic units of analysis, geospatial measures, and statistical approaches. From 145 publications matching key search terms, forty publications met the inclusion criteria. Cardiovascular and psychotropic classes accounted for the largest proportion of studies. Prescription drug claims were the primary source, and medication exposure was frequently captured as period prevalence. Medication exposure was documented across a variety of geopolitical units such as countries, provinces, regions, states, and postal codes. Most results were descriptive and formal statistical modeling capitalizing on geospatial techniques was rare. Despite the extensive research on small area variation analysis in healthcare, there are a limited number of studies that have examined geographic variation in medication use. Clearly, there is opportunity to collaborate with geographers and GIS professionals to harness the power of GIS technologies and to strengthen future medication studies by applying more robust geospatial statistical methods. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Geographical Topics Learning of Geo-Tagged Social Images.

    PubMed

    Zhang, Xiaoming; Ji, Shufan; Wang, Senzhang; Li, Zhoujun; Lv, Xueqiang

    2016-03-01

    With the availability of cheap location sensors, geotagging of images in online social media is very popular. With a large amount of geo-tagged social images, it is interesting to study how these images are shared across geographical regions and how the geographical language characteristics and vision patterns are distributed across different regions. Unlike textual document, geo-tagged social image contains multiple types of content, i.e., textual description, visual content, and geographical information. Existing approaches usually mine geographical characteristics using a subset of multiple types of image contents or combining those contents linearly, which ignore correlations between different types of contents, and their geographical distributions. Therefore, in this paper, we propose a novel method to discover geographical characteristics of geo-tagged social images using a geographical topic model called geographical topic model of social images (GTMSIs). GTMSI integrates multiple types of social image contents as well as the geographical distributions, in which image topics are modeled based on both vocabulary and visual features. In GTMSI, each region of the image would have its own topic distribution, and hence have its own language model and vision pattern. Experimental results show that our GTMSI could identify interesting topics and vision patterns, as well as provide location prediction and image tagging.

  3. Temporal and geographic patterns in population trends of brown-headed cowbirds

    USGS Publications Warehouse

    Peterjohn, B.G.; Sauer, J.R.; Schwarz, S.

    2000-01-01

    The temporal and geographic patterns in the population trends of Brown-headed Cowbirds are summarized from the North American Breeding Bird Survey. During 1966-1992, the survey-wide population declined significantly, a result of declining populations in the Eastern BBS Region, southern Great Plains, and the Pacific coast states. Increasing populations were most evident in the northern Great Plains. Cowbird populations were generally stable or increasing during 1966-1976, but their trends became more negative after 1976. The trends in cowbird populations were generally directly correlated with the trends of both host and nonhost species, suggesting that large-scale factors such as changing weather patterns, land use practices, or habitat availability were responsible for the observed temporal and geographic patterns in the trends of cowbirds and their hosts.

  4. Do geographically isolated wetlands influence landscape functions?

    USGS Publications Warehouse

    Cohen, Matthew J.; Creed, Irena F.; Alexander, Laurie C.; Basu, Nandita; Calhoun, Aram J.K.; Craft, Christopher; D’Amico, Ellen; DeKeyser, Edward S.; Fowler, Laurie; Golden, Heather E.; Jawitz, James W.; Kalla, Peter; Kirkman, L. Katherine; Lane, Charles R.; Lang, Megan; Leibowitz, Scott G.; Lewis, David Bruce; Marton, John; McLaughlin, Daniel L.; Mushet, David M.; Raanan-Kiperwas, Hadas; Rains, Mark C.; Smith, Lora; Walls, Susan C.

    2015-01-01

    Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fraction of wetland edges where many functions are enhanced, and form complexes with other water bodies to create spatial and temporal heterogeneity in the timing, flow paths, and magnitude of network connectivity. These attributes signal a critical role for GIWs in sustaining a portfolio of landscape functions, but legal protections remain weak despite preferential loss from many landscapes. GIWs lack persistent surface water connections, but this condition does not imply the absence of hydrological, biogeochemical, and biological exchanges with nearby and downstream waters. Although hydrological and biogeochemical connectivity is often episodic or slow (e.g., via groundwater), hydrologic continuity and limited evaporative solute enrichment suggest both flow generation and solute and sediment retention. Similarly, whereas biological connectivity usually requires overland dispersal, numerous organisms, including many rare or threatened species, use both GIWs and downstream waters at different times or life stages, suggesting that GIWs are critical elements of landscape habitat mosaics. Indeed, weaker hydrologic connectivity with downstream waters and constrained biological connectivity with other landscape elements are precisely what enhances some GIW functions and enables others. Based on analysis of wetland geography and synthesis of wetland functions, we argue that sustaining landscape functions requires conserving the entire continuum of wetland connectivity, including GIWs.

  5. Geographic atrophy: Etiopathogenesis and current therapies.

    PubMed

    Sastre-Ibáñez, M; Barreiro-González, A; Gallego-Pinazo, R; Dolz-Marco, R; García-Armendariz, B

    2018-01-01

    Geographic atrophy is characterized by severe visual deficit whose etiology and pathophysiology are yet to be elucidated. As a working hypothesis, oxidative damage could trigger a chronic inflammation in Bruch's membrane-RPE-choriocapillaris complex, mostly due to complement pathway overactivation. Some individuals with mutations in the complement system and other factors have diminished capacity in the modulation of the inflammatory response, which results in cell damage and waste accumulation. This accumulation of intracellular and extracellular waste products manifests as drusen and pigmentary changes that precede the atrophy of photoreceptors, RPE, choriocapillaris with an ischemic process with decreased choroid flow. All these processes can be detected as tomographic findings and autofluorescence signals that are useful in the evaluation of patients with atrophic AMD, which helps to establish an individualized prognosis. Anti-inflammatory, antioxidant and therapies that decrease the accumulation of toxins for the preservation of the RPE cells and photoreceptors are being investigated in order to slow down the progression of this disease. Copyright © 2017 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  6. Genetic Evidence of Geographical Groups among Neanderthals

    PubMed Central

    Fabre, Virginie; Condemi, Silvana; Degioanni, Anna

    2009-01-01

    The Neanderthals are a well-distinguished Middle Pleistocene population which inhabited a vast geographical area extending from Europe to western Asia and the Middle East. Since the 1950s paleoanthropological studies have suggested variability in this group. Different sub-groups have been identified in western Europe, in southern Europe and in the Middle East. On the other hand, since 1997, research has been published in paleogenetics, carried out on 15 mtDNA sequences from 12 Neanderthals. In this paper we used a new methodology derived from different bioinformatic models based on data from genetics, demography and paleoanthropology. The adequacy of each model was measured by comparisons between simulated results (obtained by BayesianSSC software) and those estimated from nucleotide sequences (obtained by DNAsp4 software). The conclusions of this study are consistent with existing paleoanthropological research and show that Neanderthals can be divided into at least three groups: one in western Europe, a second in the Southern area and a third in western Asia. Moreover, it seems from our results that the size of the Neanderthal population was not constant and that some migration occurred among the demes. PMID:19367332

  7. Inferring social ties from geographic coincidences.

    PubMed

    Crandall, David J; Backstrom, Lars; Cosley, Dan; Suri, Siddharth; Huttenlocher, Daniel; Kleinberg, Jon

    2010-12-28

    We investigate the extent to which social ties between people can be inferred from co-occurrence in time and space: Given that two people have been in approximately the same geographic locale at approximately the same time, on multiple occasions, how likely are they to know each other? Furthermore, how does this likelihood depend on the spatial and temporal proximity of the co-occurrences? Such issues arise in data originating in both online and offline domains as well as settings that capture interfaces between online and offline behavior. Here we develop a framework for quantifying the answers to such questions, and we apply this framework to publicly available data from a social media site, finding that even a very small number of co-occurrences can result in a high empirical likelihood of a social tie. We then present probabilistic models showing how such large probabilities can arise from a natural model of proximity and co-occurrence in the presence of social ties. In addition to providing a method for establishing some of the first quantifiable estimates of these measures, our findings have potential privacy implications, particularly for the ways in which social structures can be inferred from public online records that capture individuals' physical locations over time.

  8. Geographic Hotspots of Critical National Infrastructure.

    PubMed

    Thacker, Scott; Barr, Stuart; Pant, Raghav; Hall, Jim W; Alderson, David

    2017-12-01

    Failure of critical national infrastructures can result in major disruptions to society and the economy. Understanding the criticality of individual assets and the geographic areas in which they are located is essential for targeting investments to reduce risks and enhance system resilience. Within this study we provide new insights into the criticality of real-life critical infrastructure networks by integrating high-resolution data on infrastructure location, connectivity, interdependence, and usage. We propose a metric of infrastructure criticality in terms of the number of users who may be directly or indirectly disrupted by the failure of physically interdependent infrastructures. Kernel density estimation is used to integrate spatially discrete criticality values associated with individual infrastructure assets, producing a continuous surface from which statistically significant infrastructure criticality hotspots are identified. We develop a comprehensive and unique national-scale demonstration for England and Wales that utilizes previously unavailable data from the energy, transport, water, waste, and digital communications sectors. The testing of 200,000 failure scenarios identifies that hotspots are typically located around the periphery of urban areas where there are large facilities upon which many users depend or where several critical infrastructures are concentrated in one location. © 2017 Society for Risk Analysis.

  9. Ecoregions and ecoregionalization: geographical and ecological perspectives

    USGS Publications Warehouse

    Loveland, Thomas R.; Merchant, James W.

    2005-01-01

    Ecoregions, i.e., areas exhibiting relative homogeneity of ecosystems, are units of analysis that are increasingly important in environmental assessment and management. Ecoregions provide a holistic framework for flexible, comparative analysis of complex environmental problems. Ecoregions mapping has intellectual foundations in both geography and ecology. However, a hallmark of ecoregions mapping is that it is a truly interdisciplinary endeavor that demands the integration of knowledge from a multitude of sciences. Geographers emphasize the role of place, scale, and both natural and social elements when delineating and characterizing regions. Ecologists tend to focus on environmental processes with special attention given to energy flows and nutrient cycling. Integration of disparate knowledge from the many key sciences has been one of the great challenges of ecoregions mapping, and may lie at the heart of the lack of consensus on the “optimal” approach and methods to use in such work. Through a review of the principal existing US ecoregion maps, issues that should be addressed in order to advance the state of the art are identified. Research related to needs, methods, data sources, data delivery, and validation is needed. It is also important that the academic system foster education so that there is an infusion of new expertise in ecoregion mapping and use.

  10. Adaptive optics imaging of geographic atrophy.

    PubMed

    Gocho, Kiyoko; Sarda, Valérie; Falah, Sabrina; Sahel, José-Alain; Sennlaub, Florian; Benchaboune, Mustapha; Ullern, Martine; Paques, Michel

    2013-05-01

    To report the findings of en face adaptive optics (AO) near infrared (NIR) reflectance fundus flood imaging in eyes with geographic atrophy (GA). Observational clinical study of AO NIR fundus imaging was performed in 12 eyes of nine patients with GA, and in seven controls using a flood illumination camera operating at 840 nm, in addition to routine clinical examination. To document short term and midterm changes, AO imaging sessions were repeated in four patients (mean interval between sessions 21 days; median follow up 6 months). As compared with scanning laser ophthalmoscope imaging, AO NIR imaging improved the resolution of the changes affecting the RPE. Multiple hyporeflective clumps were seen within and around GA areas. Time-lapse imaging revealed micrometric-scale details of the emergence and progression of areas of atrophy as well as the complex kinetics of some hyporeflective clumps. Such dynamic changes were observed within as well as outside atrophic areas. in eyes affected by GA, AO nir imaging allows high resolution documentation of the extent of RPE damage. this also revealed that a complex, dynamic process of redistribution of hyporeflective clumps throughout the posterior pole precedes and accompanies the emergence and progression of atrophy. therefore, these clumps are probably also a biomarker of rpe damage. AO NIR imaging may, therefore, be of interest to detect the earliest stages, to document the retinal pathology and to monitor the progression oF GA. (ClinicalTrials.gov number, NCT01546181.).

  11. General Relativity

    NASA Astrophysics Data System (ADS)

    Hobson, M. P.; Efstathiou, G. P.; Lasenby, A. N.

    2006-02-01

    1. The spacetime of special relativity; 2. Manifolds and coordinates; 3. Vector calculus on manifolds; 4. Tensor calculus on manifolds; 5. Special relativity revisited; 6. Electromagnetism; 7. The equivalence principle and spacetime curvature; 8. The gravitational field equations; 9. The Schwarzschild geometry; 10. Experimental tests of general relativity; 11. Schwarzschild black holes; 12. Further spherically-symmetric geometries; 13. The Kerr geometry; 14. The Friedmann-Robertson-Walker geometry; 15. Cosmological models; 16. Inflationary cosmology; 17. Linearised general relativity; 18. Gravitational waves; 19. A variational approach to general relativity.

  12. General Dentist

    MedlinePlus

    ... information you need from the Academy of General Dentistry Friday, June 29, 2018 About | Contact InfoBites Quick ... Instead of specializing in just one area of dentistry, they can provide plenty of different services for ...

  13. General Conformity

    EPA Pesticide Factsheets

    The General Conformity requirements ensure that the actions taken by federal agencies in nonattainment and maintenance areas do not interfere with a state’s plans to meet national standards for air quality.

  14. Probabilistic Flood Mapping using Volunteered Geographical Information

    NASA Astrophysics Data System (ADS)

    Rivera, S. J.; Girons Lopez, M.; Seibert, J.; Minsker, B. S.

    2016-12-01

    Flood extent maps are widely used by decision makers and first responders to provide critical information that prevents economic impacts and the loss of human lives. These maps are usually obtained from sensory data and/or hydrologic models, which often have limited coverage in space and time. Recent developments in social media and communication technology have created a wealth of near-real-time, user-generated content during flood events in many urban areas, such as flooded locations, pictures of flooding extent and height, etc. These data could improve decision-making and response operations as events unfold. However, the integration of these data sources has been limited due to the need for methods that can extract and translate the data into useful information for decision-making. This study presents an approach that uses volunteer geographic information (VGI) and non-traditional data sources (i.e., Twitter, Flicker, YouTube, and 911 and 311 calls) to generate/update the flood extent maps in areas where no models and/or gauge data are operational. The approach combines Web-crawling and computer vision techniques to gather information about the location, extent, and water height of the flood from unstructured textual data, images, and videos. These estimates are then used to provide an updated flood extent map for areas surrounding the geo-coordinate of the VGI through the application of a Hydro Growing Region Algorithm (HGRA). HGRA combines hydrologic and image segmentation concepts to estimate a probabilistic flooding extent along the corresponding creeks. Results obtained for a case study in Austin, TX (i.e., 2015 Memorial Day flood) were comparable to those obtained by a calibrated hydrologic model and had good spatial correlation with flooding extents estimated by the Federal Emergency Management Agency (FEMA).

  15. Do geographically isolated wetlands influence landscape functions?

    PubMed Central

    Cohen, Matthew J.; Creed, Irena F.; Alexander, Laurie; Basu, Nandita B.; Calhoun, Aram J. K.; Craft, Christopher; D’Amico, Ellen; DeKeyser, Edward; Fowler, Laurie; Golden, Heather E.; Jawitz, James W.; Kalla, Peter; Kirkman, L. Katherine; Lane, Charles R.; Lang, Megan; Leibowitz, Scott G.; Lewis, David Bruce; Marton, John; McLaughlin, Daniel L.; Mushet, David M.; Raanan-Kiperwas, Hadas; Rains, Mark C.; Smith, Lora; Walls, Susan C.

    2016-01-01

    Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fraction of wetland edges where many functions are enhanced, and form complexes with other water bodies to create spatial and temporal heterogeneity in the timing, flow paths, and magnitude of network connectivity. These attributes signal a critical role for GIWs in sustaining a portfolio of landscape functions, but legal protections remain weak despite preferential loss from many landscapes. GIWs lack persistent surface water connections, but this condition does not imply the absence of hydrological, biogeochemical, and biological exchanges with nearby and downstream waters. Although hydrological and biogeochemical connectivity is often episodic or slow (e.g., via groundwater), hydrologic continuity and limited evaporative solute enrichment suggest both flow generation and solute and sediment retention. Similarly, whereas biological connectivity usually requires overland dispersal, numerous organisms, including many rare or threatened species, use both GIWs and downstream waters at different times or life stages, suggesting that GIWs are critical elements of landscape habitat mosaics. Indeed, weaker hydrologic connectivity with downstream waters and constrained biological connectivity with other landscape elements are precisely what enhances some GIW functions and enables others. Based on analysis of wetland geography and synthesis of wetland functions, we argue that sustaining landscape functions requires conserving the entire continuum of wetland connectivity, including GIWs. PMID:26858425

  16. Geographic atrophy phenotype identification by cluster analysis.

    PubMed

    Monés, Jordi; Biarnés, Marc

    2018-03-01

    To identify ocular phenotypes in patients with geographic atrophy secondary to age-related macular degeneration (GA) using a data-driven cluster analysis. This was a retrospective analysis of data from a prospective, natural history study of patients with GA who were followed for ≥6 months. Cluster analysis was used to identify subgroups within the population based on the presence of several phenotypic features: soft drusen, reticular pseudodrusen (RPD), primary foveal atrophy, increased fundus autofluorescence (FAF), greyish FAF appearance and subfoveal choroidal thickness (SFCT). A comparison of features between the subgroups was conducted, and a qualitative description of the new phenotypes was proposed. The atrophy growth rate between phenotypes was then compared. Data were analysed from 77 eyes of 77 patients with GA. Cluster analysis identified three groups: phenotype 1 was characterised by high soft drusen load, foveal atrophy and slow growth; phenotype 3 showed high RPD load, extrafoveal and greyish FAF appearance and thin SFCT; the characteristics of phenotype 2 were midway between phenotypes 1 and 3. Phenotypes differed in all measured features (p≤0.013), with decreases in the presence of soft drusen, foveal atrophy and SFCT seen from phenotypes 1 to 3 and corresponding increases in high RPD load, high FAF and greyish FAF appearance. Atrophy growth rate differed between phenotypes 1, 2 and 3 (0.63, 1.91 and 1.73 mm 2 /year, respectively, p=0.0005). Cluster analysis identified three distinct phenotypes in GA. One of them showed a particularly slow growth pattern. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  17. Monitoring bird populations in small geographic areas

    USGS Publications Warehouse

    Dunn, Erica H.; Bart, J.; Collins, B.T.; Craig, B.; Dale, B.; Downes, C.M.; Francis, C.M.; Woodley, S.; Zorn, P.

    2006-01-01

    Numerous methods exist for monitoring bird populations, and there is a large literature describing them. There are few resources, however, that provide comprehensive advice on every step of organizing and carrying out a survey, from the early stages of planning to final use of the data. Even fewer resources are designed to meet the needs of a wide variety of potential users, from amateurs interested in change of bird life in a local study preserve to professionals testing hypotheses on the response of birds to habitat management, although much of the advice should be the same for every monitoring program. Whether survey objectives are very modest or rigorously scientific, samples must be sufficiently numerous and well distributed to provide meaningful results, and the survey should be well designed to ensure that the money and effort going into it are not wasted. This document is intended to be a complete resource for anyone planning to organize monitoring of noncolonial landbirds within a relatively small geographic area (e.g., from the size of a woodlot to a large park). The first of its two parts provides background explaining the importance of good study design and gives specific advice on all aspects of project planning and execution of high-quality data collection for the purpose of hypothesis testing. The second part is self-contained and nontechnical and describes complete plans for a site-specific checklist survey, suitable for addressing monitoring questions frequently asked by amateurs and for involvement of volunteers in data collection. Throughout are references to additional resources, from background literature to sources of existing survey protocols, analysis software, and tools for archiving data.

  18. Choroidal Round Hyporeflectivities in Geographic Atrophy.

    PubMed

    Corbelli, Eleonora; Sacconi, Riccardo; De Vitis, Luigi Antonio; Carnevali, Adriano; Rabiolo, Alessandro; Querques, Lea; Bandello, Francesco; Querques, Giuseppe

    2016-01-01

    In geographic atrophy (GA), choroidal vessels typically appear on structural optical coherence tomography (OCT) as hyperreflective round areas with highly reflective borders. We observed that some GA eyes show choroidal round hyporeflectivities with highly reflective borders beneath the atrophy, and futher investigated the charcteristcs by comparing structural OCT, indocyanine green angiography (ICGA) and OCT angiography (OCT-A). Round hyporeflectivities were individuated from a pool of patients with GA secondary to non-neovascular age-related macular degeneration consecutively presenting between October 2015 and March 2016 at the Medical Retina & Imaging Unit of the University Vita-Salute San Raffaele. Patients underwent a complete ophthalmologic examination including ICGA, structural OCT and OCT-A. The correspondence between choroidal round hyporeflectivities beneath GA on structural OCT and ICGA and OCT-A imaging were analyzed. Fifty eyes of 26 consecutive patients (17 females and 9 males; mean age 76.8±6.2 years) with GA were included. Twenty-nine round hyporeflectivities have been found by OCT in choroidal layers in 21 eyes of 21 patients (42.0%; estimated prevalence of 57.7%). All 29 round hyporeflectivities showed constantly a hyperreflective border and a backscattering on structural OCT, and appeared as hypofluorescent in late phase ICGA and as dark foci with non detectable flow in the choroidal segmentation of OCT-A. Interestingly, the GA area was greater in eyes with compared to eyes without round hyporeflectivities (9.30±5.74 and 5.57±4.48mm2, respectively; p = 0.01). Our results suggest that most round hyporeflectivities beneath GA may represent non-perfused or hypo-perfused choroidal vessels with non-detectable flow.

  19. Automation technology using Geographic Information System (GIS)

    NASA Technical Reports Server (NTRS)

    Brooks, Cynthia L.

    1994-01-01

    Airport Surface Movement Area is but one of the actions taken to increase the capacity and safety of existing airport facilities. The System Integration Branch (SIB) has designed an integrated system consisting of an electronic moving display in the cockpit, and includes display of taxi routes which will warn controllers and pilots of the position of other traffic and warning information automatically. Although, this system has in test simulation proven to be accurate and helpful; the initial process of obtaining an airport layout of the taxi-routes and designing each of them is a very tedious and time-consuming process. Other methods of preparing the display maps are being researched. One such method is the use of the Geographical Information System (GIS). GIS is an integrated system of computer hardware and software linking topographical, demographic and other resource data that is being referenced. The software can support many areas of work with virtually unlimited information compatibility due to the system's open architecture. GIS will allow us to work faster with increased efficiency and accuracy while providing decision making capabilities. GIS is currently being used at the Langley Research Center with other applications and has been validated as an accurate system for that task. GIS usage for our task will involve digitizing aerial photographs of the topology for each taxi-runway and identifying each position according to its specific spatial coordinates. The information currently being used can be integrated with the GIS system, due to its ability to provide a wide variety of user interfaces. Much more research and data analysis will be needed before this technique will be used, however we are hopeful this will lead to better usage of man-power and technological capabilities for the future.

  20. Wing geometry of Phlebotomus stantoni and Sergentomyia hodgsoni from different geographical locations in Thailand.

    PubMed

    Sumruayphol, Suchada; Chittsamart, Boonruam; Polseela, Raxsina; Sriwichai, Patchara; Samung, Yudthana; Apiwathnasorn, Chamnarn; Dujardin, Jean-Pierre

    2017-01-01

    Geographic populations of the two main sandflies genera present in Thailand were studied for species and population identification. Size and shape of Phlebotomus stantoni and Sergentomyia hodgsoni from different island and mainland locations were examined by landmark-based geometric morphometrics. Intraspecific and interspecific wing comparison was carried out based on 12 anatomical landmarks. The wing centroid size of P. stantoni was generally larger than that of S. hodgsoni. Within both species, wings from the continent were significantly larger than those from island populations. Size variation could be significant between geographic locations, but could also overlap between genera. The wing venation geometry showed non-overlapping differences between two species. The within-species variation of geometric shape between different geographical locations was highly significant, but it could not interfere with the interspecies difference. The lack of species overlapping in shape, and the high discrimination between geographic populations, make geometric shape a promising character for future taxonomic and epidemiological studies. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  1. Geographic variation in mimetic precision among different species of coral snake mimics.

    PubMed

    Akcali, C K; Pfennig, D W

    2017-07-01

    Batesian mimicry is widespread, but whether and why different species of mimics vary geographically in resemblance to their model is unclear. We characterized geographic variation in mimetic precision among four Batesian mimics of coral snakes. Each mimic occurs where its model is abundant (i.e. in 'deep sympatry'), rare (i.e. at the sympatry/allopatry boundary or 'edge sympatry') and absent (i.e. in allopatry). Geographic variation in mimetic precision was qualitatively different among these mimics. In one mimic, the most precise individuals occurred in edge sympatry; in another, they occurred in deep sympatry; in the third, they occurred in allopatry; and in the fourth, precise mimics were not concentrated anywhere throughout their range. Mimicry was less precise in allopatry than in sympatry in only two mimics. We present several nonmutually exclusive hypotheses for these patterns. Generally, examining geographic variation in mimetic precision - within and among different mimics - offers novel insights into the causes and consequences of mimicry. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  2. Genetic characterization of Bombyx mori (Lepidoptera: Bombycidae) breeding and hybrid lines with different geographic origins.

    PubMed

    Furdui, Emilia M; Mărghitaş, Liviu A; Dezmirean, Daniel S; Paşca, Ioan; Pop, Iulia F; Erler, Silvio; Schlüns, Ellen A

    2014-01-01

    The domesticated silkworm Bombyx mori L. comprises a large number of geographical breeds and hybrid lines. Knowing the genetic structure of those may provide information to improve the conservation of commercial lines by estimating inbreeding over generations and the consequences of excessive use of those lineages. Here, we analyzed the genetic diversity of seven breeds and eight hybrid lines from Eastern Europe and Asia using highly polymorphic microsatellites markers to determine its genetical impact on their use in global breeding programs. No consistent pattern of deviation from Hardy-Weinberg equilibrium was found for most breed and hybrids; and the absence of a linkage disequilibrium also suggests that the strains are in equilibrium. A principal coordinate analysis revealed a clear separation of two silkworm breeds from the rest: one (IBV) originated from India and the other one (RG90) from Romania/Japan. The tendency of the other breeds from different geographic origins to cluster together in a general mix might be due to similar selection pressures (climate and anthropogenic factors) in different geographic locations. Phylogenetic analyses grouped the different silkworm breeds but not the hybrids according to their geographic origin and confirmed the pattern found in the principal coordinate analysis. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

  3. Geographic and racial-ethnic differences in satisfaction with and perceived benefits of mental health services.

    PubMed

    Kim, Giyeon; Parton, Jason M; Ford, Katy-Lauren; Bryant, Ami N; Shim, Ruth S; Parmelee, Patricia

    2014-12-01

    This study examined whether racial-ethnic differences in satisfaction with and perceived benefits from mental health services vary by geographic region among U.S. adults. Drawn from the Collaborative Psychiatric Epidemiology Surveys (CPES), selected samples consisted of 2,160 adults age 18 and older from diverse racial-ethnic groups (Asian, black, Hispanic/Latino, and white) who had used mental health services in the past 12 months. Generalized linear model analysis was conducted for the United States as a whole and separately by geographic region (Northeast, South, Midwest, and West) after adjustment for covariates. In the national sample, no significant main effects of race-ethnicity and geographic region were found in either satisfaction with or perceived benefits from mental health services. In the stratified analyses for geographic regions, however, significant racial-ethnic differences were observed in the West; blacks in the West were significantly more likely to report higher satisfaction and perceived benefits, whereas Hispanics/Latinos in the West were significantly less likely to do so. The findings suggest that there are regional variations of racial-ethnic differences in satisfaction with and perceived benefits from mental health services among U.S. adults and that addressing needs of Hispanics/Latinos in the West may help reduce racial-ethnic disparities in mental health care. Clinical and policy implications are discussed.

  4. Reptiles of Chubut province, Argentina: richness, diversity, conservation status and geographic distribution maps.

    PubMed

    Minoli, Ignacio; Morando, Mariana; Avila, Luciano Javier

    2015-01-01

    An accurate estimation of species and population geographic ranges is essential for species-focused studies and conservation and management plans. Knowledge of the geographic distributions of reptiles from Patagonian Argentina is in general limited and dispersed over manuscripts from a wide variety of topics. We completed an extensive review of reptile species of central Patagonia (Argentina) based on information from a wide variety of sources. We compiled and checked geographic distribution records from published literature and museum records, including extensive new data from the LJAMM-CNP (CENPAT-CONICET) herpetological collection. Our results show that there are 52 taxa recorded for this region and the highest species richness was seen in the families Liolaemidae and Dipsadidae with 31 and 10 species, respectively. The Patagónica was the phytogeographic province most diverse in species and Phymaturus was the genus of conservation concern most strongly associated with it. We present a detailed species list with geographical information, richness species, diversity analyses with comparisons across phytogeographical provinces, conservation status, taxonomic comments and distribution maps for all of these taxa.

  5. Reptiles of Chubut province, Argentina: richness, diversity, conservation status and geographic distribution maps

    PubMed Central

    Minoli, Ignacio; Morando, Mariana; Avila, Luciano Javier

    2015-01-01

    Abstract An accurate estimation of species and population geographic ranges is essential for species-focused studies and conservation and management plans. Knowledge of the geographic distributions of reptiles from Patagonian Argentina is in general limited and dispersed over manuscripts from a wide variety of topics. We completed an extensive review of reptile species of central Patagonia (Argentina) based on information from a wide variety of sources. We compiled and checked geographic distribution records from published literature and museum records, including extensive new data from the LJAMM-CNP (CENPAT-CONICET) herpetological collection. Our results show that there are 52 taxa recorded for this region and the highest species richness was seen in the families Liolaemidae and Dipsadidae with 31 and 10 species, respectively. The Patagónica was the phytogeographic province most diverse in species and Phymaturus was the genus of conservation concern most strongly associated with it. We present a detailed species list with geographical information, richness species, diversity analyses with comparisons across phytogeographical provinces, conservation status, taxonomic comments and distribution maps for all of these taxa. PMID:25931966

  6. Geographical mapping and Bayesian spatial modeling of malaria incidence in Sistan and Baluchistan province, Iran.

    PubMed

    Zayeri, Farid; Salehi, Masoud; Pirhosseini, Hasan

    2011-12-01

    To present the geographical map of malaria and identify some of the important environmental factors of this disease in Sistan and Baluchistan province, Iran. We used the registered malaria data to compute the standard incidence rates (SIRs) of malaria in different areas of Sistan and Baluchistan province for a nine-year period (from 2001 to 2009). Statistical analyses consisted of two different parts: geographical mapping of malaria incidence rates, and modeling the environmental factors. The empirical Bayesian estimates of malaria SIRs were utilized for geographical mapping of malaria and a Poisson random effects model was used for assessing the effect of environmental factors on malaria SIRs. In general, 64,926 new cases of malaria were registered in Sistan and Baluchistan Province from 2001 to 2009. Among them, 42,695 patients (65.8%) were male and 22,231 patients (34.2%) were female. Modeling the environmental factors showed that malaria incidence rates had positive relationship with humidity, elevation, average minimum temperature and average maximum temperature, while rainfall had negative effect on malaria SIRs in this province. The results of the present study reveals that malaria is still a serious health problem in Sistan and Baluchistan province, Iran. Geographical map and related environmental factors of malaria can help the health policy makers to intervene in high risk areas more efficiently and allocate the resources in a proper manner. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  7. Genetic Characterization of Bombyx mori (Lepidoptera: Bombycidae) Breeding and Hybrid Lines With Different Geographic Origins

    PubMed Central

    Furdui, Emilia M.; Mărghitaş, Liviu A.; Dezmirean, Daniel S.; Paşca, Ioan; Pop, Iulia F.; Erler, Silvio; Schlüns, Ellen A.

    2014-01-01

    Abstract The domesticated silkworm Bombyx mori L. comprises a large number of geographical breeds and hybrid lines. Knowing the genetic structure of those may provide information to improve the conservation of commercial lines by estimating inbreeding over generations and the consequences of excessive use of those lineages. Here, we analyzed the genetic diversity of seven breeds and eight hybrid lines from Eastern Europe and Asia using highly polymorphic microsatellites markers to determine its genetical impact on their use in global breeding programs. No consistent pattern of deviation from Hardy–Weinberg equilibrium was found for most breed and hybrids; and the absence of a linkage disequilibrium also suggests that the strains are in equilibrium. A principal coordinate analysis revealed a clear separation of two silkworm breeds from the rest: one (IBV) originated from India and the other one (RG 90 ) from Romania/Japan. The tendency of the other breeds from different geographic origins to cluster together in a general mix might be due to similar selection pressures (climate and anthropogenic factors) in different geographic locations. Phylogenetic analyses grouped the different silkworm breeds but not the hybrids according to their geographic origin and confirmed the pattern found in the principal coordinate analysis. PMID:25502023

  8. Connecting the Demographic Dots: Geographic Mobility and Birth Intentions

    ERIC Educational Resources Information Center

    Myers, Scott M.

    2010-01-01

    Having a child is a major determinant of geographic mobility. Little is known, however, about the opposite process--whether geographic mobility is a determinant of fertility. Drawing on social and human capital theories and research on fertility and migration to develop competing hypotheses, the author examines the effects of mobility on changes…

  9. Issues Surrounding the Use of Virtual Reality in Geographic Education

    ERIC Educational Resources Information Center

    Lisichenko, Richard

    2015-01-01

    As with all classroom innovations intended to improve geographic education, the adoption of virtual reality (VR) poses issues for consideration prior to endorsing its use. Of these, effectiveness, implementation, and safe use need to be addressed. Traditionally, sense of place, geographic knowledge, and firsthand experiences provided by field…

  10. Geographic Differences in the Earnings of Economics Majors

    ERIC Educational Resources Information Center

    Winters, John V.; Xu, Weineng

    2014-01-01

    Economics has been shown to be a relatively high-earning college major, but geographic differences in earnings have been largely overlooked. The authors of this article use the American Community Survey to examine geographic differences in both absolute earnings and relative earnings for economics majors. They find that there are substantial…

  11. An integrated framework for the geographic surveillance of chronic disease

    PubMed Central

    2009-01-01

    Background Geographic public health surveillance is concerned with describing and disseminating geographic information about disease and other measures of health to policy makers and the public. While methodological developments in the geographical analysis of disease are numerous, few have been integrated into a framework that also considers the effects of case ascertainment bias on the effectiveness of chronic disease surveillance. Results We present a framework for the geographic surveillance of chronic disease that integrates methodological developments in the spatial statistical analysis and case ascertainment. The framework uses an hierarchical approach to organize and model health information derived from an administrative health data system, and importantly, supports the detection and analysis of case ascertainment bias in geographic data. We test the framework on asthmatic data from Alberta, Canada. We observe high prevalence in south-western Alberta, particularly among Aboriginal females. We also observe that persons likely mistaken for asthmatics tend to be distributed in a pattern similar to asthmatics, suggesting that there may be an underlying social vulnerability to a variety of respiratory illnesses, or the presence of a diagnostic practice style effect. Finally, we note that clustering of asthmatics tends to occur at small geographic scales, while clustering of persons mistaken for asthmatics tends to occur at larger geographic scales. Conclusion Routine and ongoing geographic surveillance of chronic diseases is critical to developing an understanding of underlying epidemiology, and is critical to informing policy makers and the public about the health of the population. PMID:19948046

  12. Roundball Geography: A Successful Grass Roots Geographic Education.

    ERIC Educational Resources Information Center

    Bailey, William H.; Dawsey, Cyrus B.

    1992-01-01

    Describes a grass-roots geographic education program that combines the efforts of elementary school teachers, Auburn University (Alabama), and a local newspaper. Explains that the program is designed as an alternative to existing curriculum materials. Discusses how geographic themes are illustrated in a way that takes advantage of local interest…

  13. The Pedagogical Benefits of Participatory GIS for Geographic Education

    ERIC Educational Resources Information Center

    Sinha, Gaurav; Smucker, Thomas A.; Lovell, Eric J.; Velempini, Kgosietsile; Miller, Samuel A.; Weiner, Daniel; Wangui, Elizabeth Edna

    2017-01-01

    In this article, participatory geographic information systems GIS (PGIS) is explored and established as a powerful platform for geographic education. PGIS pedagogy can help educators meet diverse learning objectives pertaining to: (1) local knowledge and place-based thinking; (2) community engagement; (3) field mapping with geospatial…

  14. Lived and Imagined: Information and Storytelling in Geographic Systems

    ERIC Educational Resources Information Center

    Kabisch, Eric Alan

    2011-01-01

    This dissertation investigates the relationship between storytelling and information in the narration of geographic space. While storytelling has historically shaped our understanding of geography, modern practices in data collection, cartography, and geographic visualization enable one-way forms of representation that remove the negotiation and…

  15. Geographic Mobility and Social Inequality among Peruvian University Students

    ERIC Educational Resources Information Center

    Wells, Ryan; Cuenca, Ricardo; Blanco Ramirez, Gerardo; Aragón, Jorge

    2018-01-01

    The purpose of this study was to explore geographic mobility among university students in Peru and to understand how mobility patterns differ by region and by demographic indicators of inequality. The ways that students may be able to move geographically in order to access quality higher education within the educational system can be a driver of…

  16. 47 CFR 22.911 - Cellular geographic service area.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Cellular geographic service area. 22.911 Section 22.911 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Cellular Radiotelephone Service § 22.911 Cellular geographic service area. The...

  17. Geographic Variations in Public Schools' Costs. Working Paper Series.

    ERIC Educational Resources Information Center

    Chambers, Jay G.

    This report addresses the following question: How much more or less does it cost to provide the same levels of educational resources across different geographic locations in the United States? To answer this question, the report develops a comprehensive geographic cost-of-education index (GCEI) that focuses on the prices of inputs (personnel and…

  18. 47 CFR 27.15 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. (1) Parties seeking approval for... service area or disaggregate their licensed spectrum at any time following the grant of their licenses. (b...

  19. 42 CFR 412.316 - Geographic adjustment factors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Geographic adjustment factors. 412.316 Section 412... Costs § 412.316 Geographic adjustment factors. (a) Local cost variation. CMS adjusts for local cost... part. The adjustment factor equals the hospital wage index value applicable to the hospital raised to...

  20. Managing the Web-Enhanced Geographic Information Service.

    ERIC Educational Resources Information Center

    Stephens, Denise

    1997-01-01

    Examines key management issues involved in delivering geographic information services on the World Wide Web, using the Geographic Information Center (GIC) program at the University of Virginia Library as a reference. Highlights include integrating the Web into services; building collections for Web delivery; and evaluating spatial information…

  1. KBGIS-II: A knowledge-based geographic information system

    NASA Technical Reports Server (NTRS)

    Smith, Terence; Peuquet, Donna; Menon, Sudhakar; Agarwal, Pankaj

    1986-01-01

    The architecture and working of a recently implemented Knowledge-Based Geographic Information System (KBGIS-II), designed to satisfy several general criteria for the GIS, is described. The system has four major functions including query-answering, learning and editing. The main query finds constrained locations for spatial objects that are describable in a predicate-calculus based spatial object language. The main search procedures include a family of constraint-satisfaction procedures that use a spatial object knowledge base to search efficiently for complex spatial objects in large, multilayered spatial data bases. These data bases are represented in quadtree form. The search strategy is designed to reduce the computational cost of search in the average case. The learning capabilities of the system include the addition of new locations of complex spatial objects to the knowledge base as queries are answered, and the ability to learn inductively definitions of new spatial objects from examples. The new definitions are added to the knowledge base by the system. The system is performing all its designated tasks successfully. Future reports will relate performance characteristics of the system.

  2. Geographic setting influences Great Lakes beach microbiological water quality

    USGS Publications Warehouse

    Haack, Sheridan K.; Fogarty, Lisa R.; Stelzer, Erin A.; Fuller, Lori M.; Brennan, Angela K.; Isaacs, Natasha M.; Johnson, Heather E.

    2013-01-01

    Understanding of factors that influence Escherichia coli (EC) and enterococci (ENT) concentrations, pathogen occurrence, and microbial sources at Great Lakes beaches comes largely from individual beach studies. Using 12 representative beaches, we tested enrichment cultures from 273 beach water and 22 tributary samples for EC, ENT, and genes indicating the bacterial pathogens Shiga-toxin producing E. coli (STEC), Shigella spp., Salmonella spp, Campylobacter jejuni/coli, and methicillin-resistant Staphylococcus aureus, and 108–145 samples for Bacteroides human, ruminant, and gull source-marker genes. EC/ENT temporal patterns, general Bacteroides concentration, and pathogen types and occurrence were regionally consistent (up to 40 km), but beach catchment variables (drains/creeks, impervious surface, urban land cover) influenced exceedances of EC/ENT standards and detections of Salmonella and STEC. Pathogen detections were more numerous when the EC/ENT Beach Action Value (but not when the Geometric Mean and Statistical Threshold Value) was exceeded. EC, ENT, and pathogens were not necessarily influenced by the same variables. Multiple Bacteroides sources, varying by date, occurred at every beach. Study of multiple beaches in different geographic settings provided new insights on the contrasting influences of regional and local variables, and a broader-scale perspective, on significance of EC/ENT exceedances, bacterial sources, and pathogen occurrence.

  3. 32 CFR 724.601 - General.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false General. 724.601 Section 724.601 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NAVAL DISCHARGE REVIEW BOARD... applications accumulated from a given geographical area and the resources available to support distant personal...

  4. 32 CFR 724.601 - General.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 5 2014-07-01 2014-07-01 false General. 724.601 Section 724.601 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NAVAL DISCHARGE REVIEW BOARD... applications accumulated from a given geographical area and the resources available to support distant personal...

  5. 32 CFR 724.601 - General.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 5 2013-07-01 2013-07-01 false General. 724.601 Section 724.601 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NAVAL DISCHARGE REVIEW BOARD... applications accumulated from a given geographical area and the resources available to support distant personal...

  6. 32 CFR 724.601 - General.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false General. 724.601 Section 724.601 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NAVAL DISCHARGE REVIEW BOARD... applications accumulated from a given geographical area and the resources available to support distant personal...

  7. 32 CFR 724.601 - General.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 5 2012-07-01 2012-07-01 false General. 724.601 Section 724.601 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NAVAL DISCHARGE REVIEW BOARD... applications accumulated from a given geographical area and the resources available to support distant personal...

  8. 15 CFR 923.10 - General.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL RESOURCE MANAGEMENT COASTAL ZONE MANAGEMENT PROGRAM REGULATIONS Uses Subject to Management § 923.10 General. This subpart sets..., because of their direct and significant impacts on coastal waters or those geographic areas likely to be...

  9. Problems of Geography as General Education.

    ERIC Educational Resources Information Center

    Harper, Robert A.

    The increasing interdependency and regional specialization of today's world demand a new approach to the teaching of introductory geography courses. By focusing on the interrelationship of physical, cultural, and economic geography, a course for general education students can foster development of the geographic perspective on human systems needed…

  10. Geographically Specialized Magazines of the South.

    ERIC Educational Resources Information Center

    Riley, Sam G.

    A study was undertaken to gather information on magazines published in the southern United States in general and on southern city and regional magazines in particular. Data were collected for 25 southern city magazines, 24 southern regional magazines, and 21 speciality magazines from the region. The primary means of data collection was a…

  11. Enabling Research without Geographical Boundaries via Collaborative Research Infrastructures

    NASA Astrophysics Data System (ADS)

    Gesing, S.

    2016-12-01

    Collaborative research infrastructures on global scale for earth and space sciences face a plethora of challenges from technical implementations to organizational aspects. Science gateways - also known as virtual research environments (VREs) or virtual laboratories - address part of such challenges by providing end-to-end solutions to aid researchers to focus on their specific research questions without the need to become acquainted with the technical details of the complex underlying infrastructures. In general, they provide a single point of entry to tools and data irrespective of organizational boundaries and thus make scientific discoveries easier and faster. The importance of science gateways has been recognized on national as well as on international level by funding bodies and by organizations. For example, the US NSF has just funded a Science Gateways Community Institute, which offers support, consultancy and open accessible software repositories for users and developers; Horizon 2020 provides funding for virtual research environments in Europe, which has led to projects such as VRE4EIC (A Europe-wide Interoperable Virtual Research Environment to Empower Multidisciplinary Research Communities and Accelerate Innovation and Collaboration); national or continental research infrastructures such as XSEDE in the USA, Nectar in Australia or EGI in Europe support the development and uptake of science gateways; the global initiatives International Coalition on Science Gateways, the RDA Virtual Research Environment Interest Group as well as the IEEE Technical Area on Science Gateways have been founded to provide global leadership on future directions for science gateways in general and facilitate awareness for science gateways. This presentation will give an overview on these projects and initiatives aiming at supporting domain researchers and developers with measures for the efficient creation of science gateways, for increasing their usability and sustainability

  12. Sociodemographic and health characteristics, rather than primary care supply, are major drivers of geographic variation in preventable hospitalizations in Australia.

    PubMed

    Falster, Michael O; Jorm, Louisa R; Douglas, Kirsty A; Blyth, Fiona M; Elliott, Robert F; Leyland, Alastair H

    2015-05-01

    Geographic rates of preventable hospitalization are used internationally as an indicator of accessibility and quality of primary care. Much research has correlated the indicator with the supply of primary care services, yet multiple other factors may influence these admissions. To quantify the relative contributions of the supply of general practitioners (GPs) and personal sociodemographic and health characteristics, to geographic variation in preventable hospitalization. Self-reported questionnaire data for 267,091 participants in the 45 and Up Study, Australia, were linked with administrative hospital data to identify preventable hospitalizations. Multilevel Poisson models, with participants clustered in their geographic area of residence, were used to explore factors that explain geographic variation in hospitalization. GP supply, measured as full-time workload equivalents, was not a significant predictor of preventable hospitalization, and explained only a small amount (2.9%) of the geographic variation in hospitalization rates. Conversely, more than one-third (36.9%) of variation was driven by the sociodemographic composition, health, and behaviors of the population. These personal characteristics explained a greater amount of the variation for chronic conditions (37.5%) than acute (15.5%) or vaccine-preventable conditions (2.4%). Personal sociodemographic and health characteristics, rather than GP supply, are major drivers of preventable hospitalization. Their contribution varies according to condition, and if used for performance comparison purposes, geographic rates of preventable hospitalization should be reported according to individual condition or potential pathways for intervention.

  13. Sociodemographic and Health Characteristics, Rather Than Primary Care Supply, are Major Drivers of Geographic Variation in Preventable Hospitalizations in Australia

    PubMed Central

    Jorm, Louisa R.; Douglas, Kirsty A.; Blyth, Fiona M.; Elliott, Robert F.; Leyland, Alastair H.

    2015-01-01

    Background: Geographic rates of preventable hospitalization are used internationally as an indicator of accessibility and quality of primary care. Much research has correlated the indicator with the supply of primary care services, yet multiple other factors may influence these admissions. Objective: To quantify the relative contributions of the supply of general practitioners (GPs) and personal sociodemographic and health characteristics, to geographic variation in preventable hospitalization. Methods: Self-reported questionnaire data for 267,091 participants in the 45 and Up Study, Australia, were linked with administrative hospital data to identify preventable hospitalizations. Multilevel Poisson models, with participants clustered in their geographic area of residence, were used to explore factors that explain geographic variation in hospitalization. Results: GP supply, measured as full-time workload equivalents, was not a significant predictor of preventable hospitalization, and explained only a small amount (2.9%) of the geographic variation in hospitalization rates. Conversely, more than one-third (36.9%) of variation was driven by the sociodemographic composition, health, and behaviors of the population. These personal characteristics explained a greater amount of the variation for chronic conditions (37.5%) than acute (15.5%) or vaccine-preventable conditions (2.4%). Conclusions: Personal sociodemographic and health characteristics, rather than GP supply, are major drivers of preventable hospitalization. Their contribution varies according to condition, and if used for performance comparison purposes, geographic rates of preventable hospitalization should be reported according to individual condition or potential pathways for intervention. PMID:25793270

  14. Geographic variation in cowbird distribution, abundance, and parasitism

    USGS Publications Warehouse

    Morrison, M.L.; Hahn, D.C.; George, T. Luke; Dobkin, David S.

    2002-01-01

    We evaluated geographical patterns in the abundance and distribution of Brown-headed Cowbirds (Molothrus ater), and in the frequency of cowbird parasitism, across North America in relation to habitat fragmentation. We found no distinctive parasitism patterns at the national or even regional scales, but the species is most abundant in the Great Plains, the heart of their original range, and least common in the southeastern U.S. This situation is dynamic, because both the Brown-headed and two other cowbird species are actively expanding their ranges in the southern U.S. We focused almost entirely in this paper on the Brown-headed Cowbird, because it is the only endemic North American cowbird, its distribution is much wider, and it has been much more intensively studied. We determined that landscape is the most meaningful unit of scale for comparing cowbird parasitism patterns as, for example, in comparisons of northeastern and central hardwood forests within agricultural matrices, and suburbanized areas versus western coniferous forests. We concluded that cowbird parasitism patterns were broadly similar within all landscapes. Even comparisons between prominently dissimilar landscapes, such as hardwoods in agriculture and suburbia versus coniferous forest, display a striking similarity in the responses of cowbirds. Our review clearly indicated that proximity of feeding areas is the key factor influencing presence and parasitism patterns within the landscape. We considered intensity of landscape fragmentation from forest-dominated landscapes altered in a forest management context to fragmentation characterized by mixed suburbanization or agricultural development. Our review consistently identified an inverse relationship between extent of forest cover across the landscape and cowbird presence. Invariably, the variation seen in parasitism frequencies within a region was at least partially explained as a response to changes in forest cover. The most salient geographic

  15. Cryptic diversity, geographical endemism and allopolyploidy in NE Pacific seaweeds.

    PubMed

    Neiva, João; Serrão, Ester A; Anderson, Laura; Raimondi, Peter T; Martins, Neusa; Gouveia, Licínia; Paulino, Cristina; Coelho, Nelson C; Miller, Kathy Ann; Reed, Daniel C; Ladah, Lydia B; Pearson, Gareth A

    2017-01-23

    Molecular markers are revealing a much more diverse and evolutionarily complex picture of marine biodiversity than previously anticipated. Cryptic and/or endemic marine species are continually being found throughout the world oceans, predominantly in inconspicuous tropical groups but also in larger, canopy-forming taxa from well studied temperate regions. Interspecific hybridization has also been found to be prevalent in many marine groups, for instance within dense congeneric assemblages, with introgressive gene-flow being the most common outcome. Here, using a congeneric phylogeographic approach, we investigated two monotypic and geographically complementary sister genera of north-east Pacific intertidal seaweeds (Hesperophycus and Pelvetiopsis), for which preliminary molecular tests revealed unexpected conflicts consistent with unrecognized cryptic diversity and hybridization. The three recovered mtDNA clades did not match a priori species delimitations. H. californicus was congruent, whereas widespread P. limitata encompassed two additional narrow-endemic species from California - P. arborescens (here genetically confirmed) and P. hybrida sp. nov. The congruence between the genotypic clusters and the mtDNA clades was absolute. Fixed heterozygosity was apparent in a high proportion of loci in P. limitata and P. hybrida, with genetic analyses showing that the latter was composed of both H. californicus and P. arborescens genomes. All four inferred species could be distinguished based on their general morphology. This study confirmed additional diversity and reticulation within NE Pacific Hesperophycus/Pelvetiopsis, including the validity of the much endangered, modern climatic relict P. arborescens, and the identification of a new, stable allopolyploid species (P. hybrida) with clearly discernable ancestry (♀ H. californicus x ♂ P. arborescens), morphology, and geographical distribution. Allopolyploid speciation is otherwise completely unknown in brown

  16. National Geographic Education. An Interview with Gilbert M. Grosvenor, President and Chairman of the Board, National Geographic Society.

    ERIC Educational Resources Information Center

    Jumper, Sidney R.

    1991-01-01

    Presents an interview with Gilbert Grosvenor, president and chairman of the board of the National Geographic Society. Examines student and public ignorance about geography. Describes the Society's Geography Education Project, Geographic Alliance Project, and Education Foundation. Includes Grosvenor's call for greater emphasis on geography in…

  17. Teaching Poverty with Geographic Visualization and Geographic Information Systems (GIS): A Case Study of East Buffalo and Food Access

    ERIC Educational Resources Information Center

    Gjesfjeld, Christopher D.; Jung, Jin-Kyu

    2014-01-01

    Although various methods have been used to teach about poverty in the social work classroom (e.g., quantitative, historical, and qualitative), the use of geographic visualization and geographic information systems (GIS) has become a relatively new method. In our analysis of food access on the East Side of Buffalo, New York, we demonstrate the…

  18. Vitreoretinal interface changes in geographic atrophy.

    PubMed

    Abdillahi, Hannan; Enzmann, Volker; Wittwer, Valéry V; Wolf, Sebastian; Wolf-Schnurrbusch, Ute E K

    2014-09-01

    Geographic atrophy (GA) is the end-stage manifestation of atrophic age-related macular degeneration (AMD). The disease progresses slowly over time, eventually causing loss of central vision. Its cause and pathomechanism are not fully known. Previous studies have suggested that vitreoretinal traction (VRT) may contribute to the progression of neovascular AMD. The aim of this study was to examine whether an association between changes at the vitreoretinal interface (VRI), in particular traction (VRT), and the characteristics and progression of GA in eyes with dry AMD can be established. Clinic-based prospective cohort study. A total of 97 patients (age range, 61-90 years; mean, 78.4 years) with GA secondary to dry AMD were enrolled. Patients exhibiting neovascular signs on fluorescein angiography in either eye were excluded. The VRI changes were examined using spectral-domain optical coherence tomography (SD-OCT). Characteristics of GA were examined using fundus autofluorescence (FAF) imaging. All imaging was performed using a Spectralis SLO+OCT device (Heidelberg Engineering, Heidelberg, Germany); GA area was measured using the Region Finder (Heidelberg Engineering) software native to the Spectralis platform. Area and increase in area of GA. A total of 97 eyes were examined. Vitreoretinal traction was found in 39 eyes (40%). The GA area at baseline was 6.65±5.64 mm(2) in eyes with VRT and 5.73±4.72 mm(2) in eyes with no VRT. The annual rate of progression of GA area progression was 2.99±0.66 mm(2) in eyes with VRT and 1.45±0.67mm(2) in eyes without VRT. Differences between groups in both parameters were statistically significant (n = 97 total number of eyes; P<0.001). Multiple regression analysis confirmed this finding (B = 0.714, P<0.001; F3,93 = 72.542, P<0.001; adjusted R(2) = 0.691) CONCLUSIONS: Our results indicate an association between VRT and an increased rate of progression of GA area in dry AMD. Monitoring VRT may contribute to an improved estimate

  19. Geographical Variation and Social Work Students' Job Intentions in China: A Geographic Information Systems Approach.

    PubMed

    Wang, Yean; Guo, Yingqi; Zeng, Shouchui

    2018-04-01

    Social work education in China is undergoing far-reaching development. However, an important issue, low professional commitment, has been identified. Why do social work graduates-especially master's level graduates-take jobs unrelated to social work? To answer this question, it is important to take into account that the professionalization of social work is happening unevenly across China as a result of uneven social and economic development. Models used in past research do not consider the possibility that the low intention for social work jobs and its potential predictors may vary across regions. To address this problem, Geographic Information Systems software is being adopted to explore the varying degrees of social work graduates' job intention, its predictors across China, and the association between job intention and predictors at both national and regional levels. Authors of this study found substantial geographic variation in predictors of social work graduates' job intention across regions. Their findings also suggest some heterogeneity in the association between job intention and specific correlates that would be masked in the traditional nationwide model. Policymakers aiming to improve the job intention of social work graduates should consider regional variation as part of their approach.

  20. Geographical differences in the prevalence of dyspepsia.

    PubMed

    Knill-Jones, R P

    1991-01-01

    The epidemiology of dyspepsia is reviewed with reference to the factors that affect prevalence, including definitions of the term, case mix, and selection. Period prevalence of dyspepsia in several different populations gives an average of 32%, of which 24% is accounted for by recognized ulcer disease. Dyspepsia appears to comprise about 70% of patients' gastrointestinal problems in a large prospective survey carried out in general practice in England, higher than some other estimates. The proportion of gastrointestinal disease in general practice consultations is examined, and while it accounts for about 5% of all consultations, it accounts for about 14% of patients consulting with a problem. There seems to have been a decline of 15% over 30 years. The difficulty of establishing the population prevalence of functional dyspepsia is emphasized, and several studies in which the proportion in general gastrointestinal outpatients has been measured are reviewed. Some data from a Glasgow study in which clinical histories have been recorded directly from patients by a computer system (GLADYS) show the prevalence of several common gastrointestinal symptoms in a clinic population and also of dysmotility-like dyspepsia. Such descriptive data should also be used for predicting diagnosis and for selecting patients to investigate.

  1. Poverty, wealth, and health care utilization: a geographic assessment.

    PubMed

    Cooper, Richard A; Cooper, Matthew A; McGinley, Emily L; Fan, Xiaolin; Rosenthal, J Thomas

    2012-10-01

    Geographic variation has been of interest to both health planners and social epidemiologists. However, while the major focus of interest of planners has been on variation in health care spending, social epidemiologists have focused on health; and while social epidemiologists have observed strong associations between poor health and poverty, planners have concluded that income is not an important determinant of variation in spending. These different conclusions stem, at least in part, from differences in approach. Health planners have generally studied variation among large regions, such as states, counties, or hospital referral regions (HRRs), while epidemiologists have tended to study local areas, such as ZIP codes and census tracts. To better understand the basis for geographic variation in hospital utilization, we drew upon both approaches. Counties and HRRs were disaggregated into their constituent ZIP codes and census tracts and examined the interrelationships between income, disability, and hospital utilization that were examined at both the regional and local levels, using statistical and geomapping tools. Our studies centered on the Milwaukee and Los Angeles HRRs, where per capita health care utilization has been greater than elsewhere in their states. We compared Milwaukee to other HRRs in Wisconsin and Los Angeles to the other populous counties of California and to a region in California of comparable size and diversity, stretching from San Francisco to Sacramento (termed "San-Framento"). When studied at the ZIP code level, we found steep, curvilinear relationships between lower income and both increased hospital utilization and increasing percentages of individuals reporting disabilities. These associations were also evident on geomaps. They were strongest among populations of working-age adults but weaker among seniors, for whom income proved to be a poor proxy for poverty and whose residential locations deviated from the major underlying income

  2. Beyond Knee-Jerk Environmental Thinking: Teaching Geographic Perspectives on Conservation, Preservation and the Hetch Hetchy Valley Controversy

    ERIC Educational Resources Information Center

    Moseley, William G.

    2009-01-01

    Attention to scale, use of space and connections between places and regions are general, yet distinctive, geographical concepts that may be employed in introductory level human-environment geography courses to distinguish them from other environmental studies offerings. This article demonstrates how attention to the aforementioned concepts…

  3. Interactions among climate and soil properties influence current and future geographic distribution of an invasive grass in the Chihuahuan Desert

    USDA-ARS?s Scientific Manuscript database

    Background/Question/Methods: Lehmann lovegrass (Eragrostis lehmanniana) is an invasive exotic perennial grass throughout the Sonoran Desert. However, in the neighboring Chihuahuan Desert, this species is generally present in low abundance, although data on its geographic distribution are scarce. Our...

  4. Geographic Mosaic of Plant Evolution: Extrafloral Nectary Variation Mediated by Ant and Herbivore Assemblages

    PubMed Central

    Nogueira, Anselmo; Rey, Pedro J.; Alcántara, Julio M.; Feitosa, Rodrigo M.; Lohmann, Lúcia G.

    2015-01-01

    Herbivory is an ecological process that is known to generate different patterns of selection on defensive plant traits across populations. Studies on this topic could greatly benefit from the general framework of the Geographic Mosaic Theory of Coevolution (GMT). Here, we hypothesize that herbivory represents a strong pressure for extrafloral nectary (EFN) bearing plants, with differences in herbivore and ant visitor assemblages leading to different evolutionary pressures among localities and ultimately to differences in EFN abundance and function. In this study, we investigate this hypothesis by analyzing 10 populations of Anemopaegma album (30 individuals per population) distributed through ca. 600 km of Neotropical savanna and covering most of the geographic range of this plant species. A common garden experiment revealed a phenotypic differentiation in EFN abundance, in which field and experimental plants showed a similar pattern of EFN variation among populations. We also did not find significant correlations between EFN traits and ant abundance, herbivory and plant performance across localities. Instead, a more complex pattern of ant–EFN variation, a geographic mosaic, emerged throughout the geographical range of A. album. We modeled the functional relationship between EFNs and ant traits across ant species and extended this phenotypic interface to characterize local situations of phenotypic matching and mismatching at the population level. Two distinct types of phenotypic matching emerged throughout populations: (1) a population with smaller ants (Crematogaster crinosa) matched with low abundance of EFNs; and (2) seven populations with bigger ants (Camponotus species) matched with higher EFN abundances. Three matched populations showed the highest plant performance and narrower variance of EFN abundance, representing potential plant evolutionary hotspots. Cases of mismatched and matched populations with the lowest performance were associated with abundant

  5. From fields to objects: A review of geographic boundary analysis

    NASA Astrophysics Data System (ADS)

    Jacquez, G. M.; Maruca, S.; Fortin, M.-J.

    Geographic boundary analysis is a relatively new approach unfamiliar to many spatial analysts. It is best viewed as a technique for defining objects - geographic boundaries - on spatial fields, and for evaluating the statistical significance of characteristics of those boundary objects. This is accomplished using null spatial models representative of the spatial processes expected in the absence of boundary-generating phenomena. Close ties to the object-field dialectic eminently suit boundary analysis to GIS data. The majority of existing spatial methods are field-based in that they describe, estimate, or predict how attributes (variables defining the field) vary through geographic space. Such methods are appropriate for field representations but not object representations. As the object-field paradigm gains currency in geographic information science, appropriate techniques for the statistical analysis of objects are required. The methods reviewed in this paper are a promising foundation. Geographic boundary analysis is clearly a valuable addition to the spatial statistical toolbox. This paper presents the philosophy of, and motivations for geographic boundary analysis. It defines commonly used statistics for quantifying boundaries and their characteristics, as well as simulation procedures for evaluating their significance. We review applications of these techniques, with the objective of making this promising approach accessible to the GIS-spatial analysis community. We also describe the implementation of these methods within geographic boundary analysis software: GEM.

  6. Evaluation of Geographic Indices Describing Health Care Utilization.

    PubMed

    Kim, Agnus M; Park, Jong Heon; Kang, Sungchan; Kim, Yoon

    2017-01-01

    The accurate measurement of geographic patterns of health care utilization is a prerequisite for the study of geographic variations in health care utilization. While several measures have been developed to measure how accurately geographic units reflect the health care utilization patterns of residents, they have been only applied to hospitalization and need further evaluation. This study aimed to evaluate geographic indices describing health care utilization. We measured the utilization rate and four health care utilization indices (localization index, outflow index, inflow index, and net patient flow) for eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee replacement surgery, caesarean sections, hysterectomy, computed tomography scans, and magnetic resonance imaging scans) according to three levels of geographic units in Korea. Data were obtained from the National Health Insurance database in Korea. We evaluated the associations among the health care utilization indices and the utilization rates. In higher-level geographic units, the localization index tended to be high, while the inflow index and outflow index were lower. The indices showed different patterns depending on the procedure. A strong negative correlation between the localization index and the outflow index was observed for all procedures. Net patient flow showed a moderate positive correlation with the localization index and the inflow index. Health care utilization indices can be used as a proxy to describe the utilization pattern of a procedure in a geographic unit.

  7. Evaluation of Geographic Indices Describing Health Care Utilization

    PubMed Central

    Park, Jong Heon

    2017-01-01

    Objectives The accurate measurement of geographic patterns of health care utilization is a prerequisite for the study of geographic variations in health care utilization. While several measures have been developed to measure how accurately geographic units reflect the health care utilization patterns of residents, they have been only applied to hospitalization and need further evaluation. This study aimed to evaluate geographic indices describing health care utilization. Methods We measured the utilization rate and four health care utilization indices (localization index, outflow index, inflow index, and net patient flow) for eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee replacement surgery, caesarean sections, hysterectomy, computed tomography scans, and magnetic resonance imaging scans) according to three levels of geographic units in Korea. Data were obtained from the National Health Insurance database in Korea. We evaluated the associations among the health care utilization indices and the utilization rates. Results In higher-level geographic units, the localization index tended to be high, while the inflow index and outflow index were lower. The indices showed different patterns depending on the procedure. A strong negative correlation between the localization index and the outflow index was observed for all procedures. Net patient flow showed a moderate positive correlation with the localization index and the inflow index. Conclusions Health care utilization indices can be used as a proxy to describe the utilization pattern of a procedure in a geographic unit. PMID:28173689

  8. Identification of General Patterns of Sex-Biased Expression in Daphnia, a Genus with Environmental Sex Determination

    PubMed Central

    Molinier, Cécile; Reisser, Céline M.O.; Fields, Peter; Ségard, Adeline; Galimov, Yan; Haag, Christoph R.

    2018-01-01

    Daphnia reproduce by cyclic-parthenogenesis, where phases of asexual reproduction are intermitted by sexual production of diapause stages. This life cycle, together with environmental sex determination, allow the comparison of gene expression between genetically identical males and females. We investigated gene expression differences between males and females in four genotypes of Daphnia magna and compared the results with published data on sex-biased gene expression in two other Daphnia species, each representing one of the major phylogenetic clades within the genus. We found that 42% of all annotated genes showed sex-biased expression in D. magna. This proportion is similar both to estimates from other Daphnia species as well as from species with genetic sex determination, suggesting that sex-biased expression is not reduced under environmental sex determination. Among 7453 single copy, one-to-one orthologs in the three Daphnia species, 707 consistently showed sex-biased expression and 675 were biased in the same direction in all three species. Hence these genes represent a core-set of genes with consistent sex-differential expression in the genus. A functional analysis identified that several of them are involved in known sex determination pathways. Moreover, 75% were overexpressed in females rather than males, a pattern that appears to be a general feature of sex-biased gene expression in Daphnia. PMID:29535148

  9. Identification of General Patterns of Sex-Biased Expression in Daphnia, a Genus with Environmental Sex Determination.

    PubMed

    Molinier, Cécile; Reisser, Céline M O; Fields, Peter; Ségard, Adeline; Galimov, Yan; Haag, Christoph R

    2018-05-04

    Daphnia reproduce by cyclic-parthenogenesis, where phases of asexual reproduction are intermitted by sexual production of diapause stages. This life cycle, together with environmental sex determination, allow the comparison of gene expression between genetically identical males and females. We investigated gene expression differences between males and females in four genotypes of Daphnia magna and compared the results with published data on sex-biased gene expression in two other Daphnia species, each representing one of the major phylogenetic clades within the genus. We found that 42% of all annotated genes showed sex-biased expression in D. magna This proportion is similar both to estimates from other Daphnia species as well as from species with genetic sex determination, suggesting that sex-biased expression is not reduced under environmental sex determination. Among 7453 single copy, one-to-one orthologs in the three Daphnia species, 707 consistently showed sex-biased expression and 675 were biased in the same direction in all three species. Hence these genes represent a core-set of genes with consistent sex-differential expression in the genus. A functional analysis identified that several of them are involved in known sex determination pathways. Moreover, 75% were overexpressed in females rather than males, a pattern that appears to be a general feature of sex-biased gene expression in Daphnia . Copyright © 2018 Molinier et al.

  10. Scrotal tongue and geographic tongue: polygenic and associated traits.

    PubMed

    Eidelman, E; Chosack, A; Cohen, T

    1976-11-01

    The familial nature of scrotal and geographic tongue was investigated in parents and siblings of 156 probands having these conditions. The prevalence in parents and siblings was significantly higher than that in the control populations. The prevalence in sibilings from families in which at least one parent was also affected was significantly higher than that in siblings from families in which neither parent was affected. The prevalence of scrotal tongue alone in siblins was similar irrespective of the condition in the proband. The prevalence of geographic tongue alone was highest in siblins of probands having only geographic tongue. A polygenic mode of inheritance with some genes common to both conditions is suggested.

  11. Generalizing entanglement

    NASA Astrophysics Data System (ADS)

    Jia, Ding

    2017-12-01

    The expected indefinite causal structure in quantum gravity poses a challenge to the notion of entanglement: If two parties are in an indefinite causal relation of being causally connected and not, can they still be entangled? If so, how does one measure the amount of entanglement? We propose to generalize the notions of entanglement and entanglement measure to address these questions. Importantly, the generalization opens the path to study quantum entanglement of states, channels, networks, and processes with definite or indefinite causal structure in a unified fashion, e.g., we show that the entanglement distillation capacity of a state, the quantum communication capacity of a channel, and the entanglement generation capacity of a network or a process are different manifestations of one and the same entanglement measure.

  12. Species are not most abundant in the centre of their geographic range or climatic niche.

    PubMed

    Dallas, Tad; Decker, Robin R; Hastings, Alan

    2017-12-01

    The pervasive idea that species should be most abundant in the centre of their geographic range or centre of their climatic niche is a key assumption in many existing ecological hypotheses and has been declared a general macroecological rule. However, empirical support for decreasing population abundance with increasing distance from geographic range or climatic niche centre (distance-abundance relationships) remains fairly weak. We examine over 1400 bird, mammal, fish and tree species to provide a thorough test of distance-abundance relationships, and their associations with species traits and phylogenetic relationships. We failed to detect consistent distance-abundance relationships, and found no association between distance-abundance slope and species traits or phylogenetic relatedness. Together, our analyses suggest that distance-abundance relationships may be rare, difficult to detect, or are an oversimplification of the complex biogeographical forces that determine species spatial abundance patterns. © 2017 John Wiley & Sons Ltd/CNRS.

  13. [Geographical distribution of physicians in Chile].

    PubMed

    Goic, A

    1995-03-01

    In 1994, Chile had 15,451 active physicians (less than 70 years old) for a population of 14,027,344 with a ratio of 1 physician per 908 inhabitants, a satisfactory figure compared to other countries of similar socio-economical development. Ratios of 1:880 and 1:843 are projected for 1999 and 2004 respectively. The annual rate of physician's population growth (2.2%), that is superior to the general population's growth rate (1.6%), will increase to about 2.5% per annum in 2001 as a consequence of the creation of three new medical schools. However, the distribution of physicians along the country is unsatisfactory. While the capital (Metropolitan Region) has a ratio of 1 physician per 629 inhabitants, the figure for the Region of Maule is 1:2,113. Only two of ten regions, excepting the capital, have a ratio lower than 1:1,000. Sixty percent of physicians live in Santiago while only 40% of the general population does so, illustrating their high concentration. Median ratio in Chile, that better reflects the reality than the mean, is 1:1,280. The heterogeneous distribution of physicians in Chile is a sign of social inequity that must be corrected. In a free society a better physician distribution is achieved with economical and professional incentives given by health institutions.

  14. Geographic information system for pigweed distribution in the US Southeast

    USDA-ARS?s Scientific Manuscript database

    In the southeastern United States, pigweeds have become troublesome weeds in agricultural systems. To implement management strategies to control them, agriculturalists need information on areas affected by pigweeds. Geographic information systems (GIS) afford users the ability to evaluate agricult...

  15. Order from noise: Toward a social theory of geographic information

    USGS Publications Warehouse

    Poore, B.S.; Chrisman, N.R.

    2006-01-01

    In the so-called Information Age, it is surprising that the concept of information is imprecisely defined and almost taken for granted. Historic and recent geographic information science (GIScience) literature relies on two conflicting metaphors, often espoused by the same author in adjacent paragraphs. The metaphor of invariance, derived from telecommunications engineering, defines information as a thing to be transported without loss through a conduit. Another metaphor, originating in the utopian movements of the 19th century, locates information within a hierarchy of refinement-a stopping place on the path to convert mere data into higher forms of knowledge and perhaps to wisdom. Both metaphors rely on long-forgotten debates outside geography and preclude us from seeing that there are important social and ethical concerns in the relationship between geographic information technologies and society. We examine the conflicts between competing metaphors and propose a social theory of geographic information. ?? 2006 by Association of American Geographers.

  16. Three geographic decomposition approaches in transportation network analysis

    DOT National Transportation Integrated Search

    1980-03-01

    This document describes the results of research into the application of geographic decomposition techniques to practical transportation network problems. Three approaches are described for the solution of the traffic assignment problem. One approach ...

  17. Applications of geographic information systems for planning and environmental linkages

    DOT National Transportation Integrated Search

    2007-11-30

    On October 4-5, 2007, the Federal Highway Administration's (FHWA) Office of Environment, Planning, and Real Estate Services sponsored a 1.5-day peer exchange focusing on select State Departments of Transportation (DOTs) applications of Geographic Inf...

  18. Integrating geographically isolated wetlands into land management decisions

    EPA Science Inventory

    Wetlands across the globe provide extensive ecosystem services. However, many wetlands – especially those surrounded by uplands, often referred to as geographically isolated wetlands (GIWs) – remain poorly protected. Protection and restoration of wetlands frequently r...

  19. Wyoming Department of Transportation geographic information system implementation project

    DOT National Transportation Integrated Search

    2000-01-01

    A geographic information system (GIS) was needed by the Wyoming Department of Transportation (WYDOT) to complement existing information management procedures and leverage the spatial components of its data. WYDOT contracted with Environmental Systems...

  20. Case studies in geographic information systems for environmental streamlining

    DOT National Transportation Integrated Search

    2012-05-31

    This 2012 summary report addresses the current use of geographic information systems (GIS) and related technologies by State Departments of Transportation (DOTs) for environmental streamlining and stewardship, particularly in relation to the National...

  1. Putting Connectivity in Context: Overview on Geographically Isolated Wetland Research

    EPA Science Inventory

    Geographically isolated wetlands (GIWs) affect and contribute to the integrity of other waters through biological, chemical, and hydrological (or physical) processes that vary in timing, duration, and magnitude of their impact. Research quantifying contributions and effects of so...

  2. Correlation dimensions of climate subsystems and their geographic variability

    NASA Astrophysics Data System (ADS)

    Gan, Thian Yew; Wang, Qiang; Seneka, Michael

    2002-12-01

    The correlation dimension D2 of precipitation (Canada and Africa), air temperature (Canada, New Zealand, and Southern Hemisphere), geo-potential height (Canada), and unregulated streamflow (Canada, USA, and Africa) were estimated using the Hill procedure of Mikosch and Wang [1995] and the bias correction of Wang and Gan [1998]. After bias correction, it seems that D2 is distinct between climate subsystems, such that for precipitation, it is between 8 and 9, for streamflow, it is between 7 and 9, for temperature, it is between 10 and 11, and for geo-potential heights, it is between 12 and 14. The results seem to suggest that climate might be viewed as a loosely coupled set of fairly high-dimensional subsystems and that different climate variables can yield different D2 values. Further, results also suggest that the D2 values of the climate subsystems studied, generally, have low geographic variability, as found between the precipitation data of Western Canada and Uganda, between the streamflow data of basins representing wide range climate and scales from Canada, USA, and Africa, and among the temperature data of Western Canada, New Zealand, and the southern hemisphere, and that the original D2 values analyzed from Canadian geo-potential heights are similar to that of Western Europe, eastern North America, and Germany. There is at most a weak relationship among basin physical characteristics, location, basin scale, and streamflow D2, while climatic influence is more obvious, as shown by drier basins having slightly higher D2 values than basins of wetter climate, basins from temperate climate having higher D2 values than those from cold or hot climates, and comparable D2 values between precipitation and streamflow data.

  3. Strain variation and geographic endemism in Streptococcus iniae.

    PubMed

    Kvitt, H; Colorni, A

    2004-10-21

    Twenty-six Israeli isolates of Streptococcus iniae from both marine and fresh/brackish water sources were compared with each other and with 9 foreign isolates. All the isolates were tentatively identified according to their biochemical profile. Direct sequencing of approximately 600 bp PCR products of the 16S rDNA confirmed their identification as S. iniae at the molecular level and revealed a new (one-nucleotide) variant among Israeli isolates, in addition to 2 variants that had been previously reported. Strain variation was further examined by subjecting the isolates to randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analyses. The RAPD method allowed separation of the isolates into only 2 groups, one including 5 Israeli fresh/brackish water isolates and one including all the other isolates. The AFLP method grouped the Israeli marine isolates into one homogeneous cluster, although they had been obtained in different years (1995 to 2001) from different species of fish, and from wild (Red Sea) as well as cultured (both Mediterranean and Red Sea) sources. The Israeli fresh/brackish water isolates and foreign isolates separated into distinct entities that clustered at generally high degrees of similarity. The distance between the clusters of the Israeli marine and fresh/brackish water isolates indicates that the S. iniae streptococcosis that has been afflicting the aquaculture industries in the 2 environments in recent years was caused by distinct strains. AFLP showed superior discriminative properties over RAPD in detecting intraspecific variation and proved to be an important tool for the characterization of S. iniae. A correlation between strain variation and geographic endemism was established.

  4. The significant surface-water connectivity of "geographically isolated wetlands"

    USGS Publications Warehouse

    Calhoun, Aram J.K.; Mushet, David M.; Alexander, Laurie C.; DeKeyser, Edward S.; Fowler, Laurie; Lane, Charles R.; Lang, Megan W.; Rains, Mark C.; Richter, Stephen; Walls, Susan

    2017-01-01

    We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of grouping wetlands based on the singular condition of being surrounded by uplands. The most recent research on wetlands considered to be “geographically isolated” shows the difficulties in grouping an ecological resource that does not reliably indicate lack of surface water connectivity in order to meet legal, regulatory, or scientific needs. Additionally, the practice of identifying “geographically isolated wetlands” based on distance from a stream can result in gross overestimates of the number of wetlands lacking ecologically important surface-water connections. Our findings do not support use of the overly simplistic label of “geographically isolated wetlands”. Wetlands surrounded by uplands vary in function and surface-water connections based on wetland landscape setting, context, climate, and geographic region and should be evaluated as such. We found that the “geographically isolated” grouping does not reflect our understanding of the hydrologic variability of these wetlands and hence does not benefit conservation of the Nation’s diverse wetland resources. Therefore, we strongly discourage use of categorizations that provide overly simplistic views of surface-water connectivity of wetlands fully embedded in upland landscapes.

  5. a Conceptual Framework for Virtual Geographic Environments Knowledge Engineering

    NASA Astrophysics Data System (ADS)

    You, Lan; Lin, Hui

    2016-06-01

    VGE geographic knowledge refers to the abstract and repeatable geo-information which is related to the geo-science problem, geographical phenomena and geographical laws supported by VGE. That includes expert experiences, evolution rule, simulation processes and prediction results in VGE. This paper proposes a conceptual framework for VGE knowledge engineering in order to effectively manage and use geographic knowledge in VGE. Our approach relies on previous well established theories on knowledge engineering and VGE. The main contribution of this report is following: (1) The concepts of VGE knowledge and VGE knowledge engineering which are defined clearly; (2) features about VGE knowledge different with common knowledge; (3) geographic knowledge evolution process that help users rapidly acquire knowledge in VGE; and (4) a conceptual framework for VGE knowledge engineering providing the supporting methodologies system for building an intelligent VGE. This conceptual framework systematically describes the related VGE knowledge theories and key technologies. That will promote the rapid transformation from geodata to geographic knowledge, and furtherly reduce the gap between the data explosion and knowledge absence.

  6. Geographic range did not confer resilience to extinction in terrestrial vertebrates at the end-Triassic crisis.

    PubMed

    Dunhill, Alexander M; Wills, Matthew A

    2015-08-11

    Rates of extinction vary greatly through geological time, with losses particularly concentrated in mass extinctions. Species duration at other times varies greatly, but the reasons for this are unclear. Geographical range correlates with lineage duration amongst marine invertebrates, but it is less clear how far this generality extends to other groups in other habitats. It is also unclear whether a wide geographical distribution makes groups more likely to survive mass extinctions. Here we test for extinction selectivity amongst terrestrial vertebrates across the end-Triassic event. We demonstrate that terrestrial vertebrate clades with larger geographical ranges were more resilient to extinction than those with smaller ranges throughout the Triassic and Jurassic. However, this relationship weakened with increasing proximity to the end-Triassic mass extinction, breaking down altogether across the event itself. We demonstrate that these findings are not a function of sampling biases; a perennial issue in studies of this kind.

  7. Geographic location and phylogeny are the main determinants of the size of the geographical range in aquatic beetles

    PubMed Central

    2011-01-01

    Background Why some species are widespread while others are very restricted geographically is one of the most basic questions in biology, although it remains largely unanswered. This is particularly the case for groups of closely related species, which often display large differences in the size of the geographical range despite sharing many other factors due to their common phylogenetic inheritance. We used ten lineages of aquatic Coleoptera from the western Palearctic to test in a comparative framework a broad set of possible determinants of range size: species' age, differences in ecological tolerance, dispersal ability and geographic location. Results When all factors were combined in multiple regression models between 60-98% of the variance was explained by geographic location and phylogenetic signal. Maximum latitudinal and longitudinal limits were positively correlated with range size, with species at the most northern latitudes and eastern longitudes displaying the largest ranges. In lineages with lotic and lentic species, the lentic (better dispersers) display larger distributional ranges than the lotic species (worse dispersers). The size of the geographical range was also positively correlated with the extent of the biomes in which the species is found, but we did not find evidence of a clear relationship between range size and age of the species. Conclusions Our findings show that range size of a species is shaped by an interplay of geographic and ecological factors, with a phylogenetic component affecting both of them. The understanding of the factors that determine the size and geographical location of the distributional range of species is fundamental to the study of the origin and assemblage of the current biota. Our results show that for this purpose the most relevant data may be the phylogenetic history of the species and its geographical location. PMID:22122885

  8. Geographic extent and variation of a coral reef trophic cascade.

    PubMed

    McClanahan, T R; Muthiga, N A

    2016-07-01

    Trophic cascades caused by a reduction in predators of sea urchins have been reported in Indian Ocean and Caribbean coral reefs. Previous studies have been constrained by their site-specific nature and limited spatial replication, which has produced site and species-specific understanding that can potentially preclude larger community-organization nuances and generalizations. In this study, we aimed to evaluate the extent and variability of the cascade community in response to fishing across ~23° of latitude and longitude in coral reefs in the southwestern Indian Ocean. The taxonomic composition of predators of sea urchins, the sea urchin community itself, and potential effects of changing grazer abundance on the calcifying benthic organisms were studied in 171 unique coral reef sites. We found that geography and habitat were less important than the predator-prey relationships. There were seven sea urchin community clusters that aligned with a gradient of declining fishable biomass and the abundance of a key predator, the orange-lined triggerfish (Balistapus undulatus). The orange-lined triggerfish dominated where sea urchin numbers and diversity were low but the relative abundance of wrasses and emperors increased where sea urchin numbers were high. Two-thirds of the study sites had high sea urchin biomass (>2,300 kg/ha) and could be dominated by four different sea urchin species, Echinothrix diadema, Diadema savignyi, D. setosum, and Echinometra mathaei, depending on the community of sea urchin predators, geographic location, and water depth. One-third of the sites had low sea urchin biomass and diversity and were typified by high fish biomass, predators of sea urchins, and herbivore abundance, representing lightly fished communities with generally higher cover of calcifying algae. Calcifying algal cover was associated with low urchin abundance where as noncalcifying fleshy algal cover was not clearly associated with herbivore abundance. Fishing of the orange

  9. Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): A range-wide synthesis.

    PubMed

    Hileman, Eric T; King, Richard B; Adamski, John M; Anton, Thomas G; Bailey, Robyn L; Baker, Sarah J; Bieser, Nickolas D; Bell, Thomas A; Bissell, Kristin M; Bradke, Danielle R; Campa, Henry; Casper, Gary S; Cedar, Karen; Cross, Matthew D; DeGregorio, Brett A; Dreslik, Michael J; Faust, Lisa J; Harvey, Daniel S; Hay, Robert W; Jellen, Benjamin C; Johnson, Brent D; Johnson, Glenn; Kiel, Brooke D; Kingsbury, Bruce A; Kowalski, Matthew J; Lee, Yu Man; Lentini, Andrew M; Marshall, John C; Mauger, David; Moore, Jennifer A; Paloski, Rori A; Phillips, Christopher A; Pratt, Paul D; Preney, Thomas; Prior, Kent A; Promaine, Andrew; Redmer, Michael; Reinert, Howard K; Rouse, Jeremy D; Shoemaker, Kevin T; Sutton, Scott; VanDeWalle, Terry J; Weatherhead, Patrick J; Wynn, Doug; Yagi, Anne

    2017-01-01

    Elucidating how life history traits vary geographically is important to understanding variation in population dynamics. Because many aspects of ectotherm life history are climate-dependent, geographic variation in climate is expected to have a large impact on population dynamics through effects on annual survival, body size, growth rate, age at first reproduction, size-fecundity relationship, and reproductive frequency. The Eastern Massasauga (Sistrurus catenatus) is a small, imperiled North American rattlesnake with a distribution centered on the Great Lakes region, where lake effects strongly influence local conditions. To address Eastern Massasauga life history data gaps, we compiled data from 47 study sites representing 38 counties across the range. We used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. We found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size-fecundity relationship and growth prior to first hibernation both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Our results provide insights into ectotherm life history variation and fill critical data gaps, which will inform Eastern Massasauga conservation efforts by improving biological realism for models of population viability and climate change.

  10. Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): A range-wide synthesis

    PubMed Central

    King, Richard B.; Adamski, John M.; Anton, Thomas G.; Bailey, Robyn L.; Baker, Sarah J.; Bieser, Nickolas D.; Bell, Thomas A.; Bissell, Kristin M.; Bradke, Danielle R.; Campa, Henry; Casper, Gary S.; Cedar, Karen; Cross, Matthew D.; DeGregorio, Brett A.; Dreslik, Michael J.; Faust, Lisa J.; Harvey, Daniel S.; Hay, Robert W.; Jellen, Benjamin C.; Johnson, Brent D.; Johnson, Glenn; Kiel, Brooke D.; Kingsbury, Bruce A.; Kowalski, Matthew J.; Lee, Yu Man; Lentini, Andrew M.; Marshall, John C.; Mauger, David; Moore, Jennifer A.; Paloski, Rori A.; Phillips, Christopher A.; Pratt, Paul D.; Preney, Thomas; Prior, Kent A.; Promaine, Andrew; Redmer, Michael; Reinert, Howard K.; Rouse, Jeremy D.; Shoemaker, Kevin T.; Sutton, Scott; VanDeWalle, Terry J.; Weatherhead, Patrick J.; Wynn, Doug; Yagi, Anne

    2017-01-01

    Elucidating how life history traits vary geographically is important to understanding variation in population dynamics. Because many aspects of ectotherm life history are climate-dependent, geographic variation in climate is expected to have a large impact on population dynamics through effects on annual survival, body size, growth rate, age at first reproduction, size–fecundity relationship, and reproductive frequency. The Eastern Massasauga (Sistrurus catenatus) is a small, imperiled North American rattlesnake with a distribution centered on the Great Lakes region, where lake effects strongly influence local conditions. To address Eastern Massasauga life history data gaps, we compiled data from 47 study sites representing 38 counties across the range. We used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. We found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size–fecundity relationship and growth prior to first hibernation both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Our results provide insights into ectotherm life history variation and fill critical data gaps, which will inform Eastern Massasauga conservation efforts by improving biological realism for models of population viability and climate change. PMID:28196149

  11. Geographic variations in the cost of spine surgery.

    PubMed

    Goz, Vadim; Rane, Ajinkya; Abtahi, Amir M; Lawrence, Brandon D; Brodke, Darrel S; Spiker, William Ryan

    2015-09-01

    Retrospective review. To define the geographic variation in costs of anterior cervical discectomy and fusion (ACDF) and posterolateral fusion (PLF). ACDF and lumbar PLF are common procedures that are used in the treatment of spinal pathologies. To optimize value, both the benefits and costs of an intervention must be quantified. Data on costs are scarce in comparison with data on total charges. This study aims at defining the costs of ACDF and PLF and describing the geographic variation within the United States. Medicare Provider Utilization and Payment data were used to investigate the costs associated with ACDF, PLF, and total knee arthroplasty (TKA). Average total costs of the procedures were compared by state and geographic region. Combined professional and facility costs for a single-level ACDF had a national mean of $13,899. Total costs for a single-level PLF had a mean of $25,858. Total costs for a primary TKA had a national mean of $13,039. The cost increased to an average of $22,138 for TKA with major comorbidities. Analysis of geographic trends showed statistically significant differences in total costs of PLF, TKA, and TKA, with major complications or comorbidities between geographic regions (P < 0.01 for all). Three of the 4 procedures (PLF, TKA, and TKA with major complications or comorbidities) showed statistically significant variation in cost between geographic regions. The Midwest provided the lowest cost for all procedures. Similar geographic trends in the cost of spinal fusions and TKAs suggest that these trends may not be limited to spine-related procedures. Surgical costs were found to correlate with cost of living but were not associated with the population of the state. These data shed light on the actual cost of common surgical procedures throughout the United States and will allow further progress toward the development of cost-effective, value-driven care. 3.

  12. Geographic range size and extinction risk assessment in nomadic species.

    PubMed

    Runge, Claire A; Tulloch, Ayesha; Hammill, Edd; Possingham, Hugh P; Fuller, Richard A

    2015-06-01

    Geographic range size is often conceptualized as a fixed attribute of a species and treated as such for the purposes of quantification of extinction risk; species occupying smaller geographic ranges are assumed to have a higher risk of extinction, all else being equal. However many species are mobile, and their movements range from relatively predictable to-and-fro migrations to complex irregular movements shown by nomadic species. These movements can lead to substantial temporary expansion and contraction of geographic ranges, potentially to levels which may pose an extinction risk. By linking occurrence data with environmental conditions at the time of observations of nomadic species, we modeled the dynamic distributions of 43 arid-zone nomadic bird species across the Australian continent for each month over 11 years and calculated minimum range size and extent of fluctuation in geographic range size from these models. There was enormous variability in predicted spatial distribution over time; 10 species varied in estimated geographic range size by more than an order of magnitude, and 2 species varied by >2 orders of magnitude. During times of poor environmental conditions, several species not currently classified as globally threatened contracted their ranges to very small areas, despite their normally large geographic range size. This finding raises questions about the adequacy of conventional assessments of extinction risk based on static geographic range size (e.g., IUCN Red Listing). Climate change is predicted to affect the pattern of resource fluctuations across much of the southern hemisphere, where nomadism is the dominant form of animal movement, so it is critical we begin to understand the consequences of this for accurate threat assessment of nomadic species. Our approach provides a tool for discovering spatial dynamics in highly mobile species and can be used to unlock valuable information for improved extinction risk assessment and conservation

  13. Mining geographic variations of Plasmodium vivax for active surveillance: a case study in China.

    PubMed

    Shi, Benyun; Tan, Qi; Zhou, Xiao-Nong; Liu, Jiming

    2015-05-27

    , the proposed space-time model is general and can readily be extended to investigate geographic variations of other diseases. Practically, such a computational model will offer new insights into active surveillance and strategic planning for disease surveillance and control.

  14. Population analysis of Vibrio parahaemolyticus originating from different geographical regions demonstrates a high genetic diversity.

    PubMed

    Urmersbach, Sara; Alter, Thomas; Koralage, Madura Sanjeevani Gonsal; Sperling, Lisa; Gerdts, Gunnar; Messelhäusser, Ute; Huehn, Stephan

    2014-03-08

    Vibrio parahaemolyticus is frequently isolated from environmental and seafood samples and associated with gastroenteritis outbreakes in American, European, Asian and African countries. To distinguish between different lineages of V. parahaemolyticus various genotyping techniques have been used, incl. multilocus sequence typing (MLST). Even though some studies have already applied MLST analysis to characterize V. parahaemolyticus strain sets, these studies have been restricted to specific geographical areas (e.g. U.S. coast, Thailand and Peru), have focused exclusively on pandemic or non-pandemic pathogenic isolates or have been based on a limited strain number. To generate a global picture of V. parahaemolyticus genotype distribution, a collection of 130 environmental and seafood related V. parahaemolyticus isolates of different geographical origins (Sri Lanka, Ecuador, North Sea and Baltic Sea as well as German retail) was subjected to MLST analysis after modification of gyrB and recA PCRs. The V. parahaemolyticus population was composed of 82 unique Sequence Types (STs), of which 68 (82.9%) were new to the pubMLST database. After translating the in-frame nucleotide sequences into amino acid sequences, less diversity was detectable: a total of 31 different peptide Sequence Types (pSTs) with 19 (61.3%) new pSTs were generated from the analyzed isolates. Most STs did not show a global dissemination, but some were supra-regionally distributed and clusters of STs were dependent on geographical origin. On peptide level no general clustering of strains from specific geographical regions was observed, thereby the most common pSTs were found on all continents (Asia, South America and Europe) and rare pSTs were restricted to distinct countries or even geographical regions. One lineage of pSTs associated only with strains from North and Baltic Sea strains was identified. Our study reveals a high genetic diversity in the analyzed V. parahaemolyticus strain set as well as for

  15. The geographic epidemiology of Mycobacterium tuberculosis disease in Baltimore, 1971-1995

    NASA Astrophysics Data System (ADS)

    Obasanjo, Olugbenga Olufemi

    Given the reemergence of Tuberculosis (TB) in the United States (U.S.) in the 1980s and 1990s, several strategies have emerged to combat the disease. A successful tool has been Directly Observed Therapy (DOT). Chaulk, et al. showed that DOT was responsible for the maintaining the decline in TB rates in Baltimore through the corresponding period of an upswing in rates nationally. In this study, we measure the impact of DOT on the geographic pattern of TB in Baltimore. We used Geographical Information System (GIS) methods to compare the geographic patterns of TB in Baltimore before and after the introduction of DOT in the city. We identified both predictors of TB, and differences in geographic units in Baltimore over time. We measured the impact of the introduction of DOT and Rifampin on various treatment outcomes for TB at about the same time. Despite the drop in numbers of TB cases, the spatial distribution of cases generally remained unchanged until 1995. This was confirmed by the fact that similar predictors were identified in all of the years that were analyzed. However, higher proportions of TB cases were found among blacks and females in more recent years. Death rates have increased significantly while corresponding relapse rates and the mean length of therapy have declined significantly. Rifampin was associated with a longer length of therapy before DOT, but with a shorter duration of therapy following the introduction of DOT. In all of the years analyzed, losses to follow-up (LTFU) do not differ from those completing therapy and are not spatially clustered relative to those completing therapy. DOT has been effective in reducing the numbers of TB cases in Baltimore city-wide without an emphasis on so-called "high-risk" patients for LTFU. Thus, any declines in TB case rates are not due to a decline in a particular group or geographic sector of the city. Universal DOT is effective and does not cause a geographic clustering of difficult-to-reach patients. This

  16. [New findings on the geographic distribution of the verrucarum group (Diptera: Psychodidae) in Colombia].

    PubMed

    Bejarano, Eduar Elías; Sierra, Diana; Vélez, Iván Darío

    2003-09-01

    The incrimination of sand flies belonging to verrucarum species group in the leishmaniasis transmission underscores the need for a detailed information on the geographical distribution of these species. The current listing adds 34 new records that extend significantly the knowledge of the geographical distribution of the verrucarum group in Colombia. The most important new records pertain to Lutzomyia spinicrassa in the tropical dry forest of the Atlantic coast, Lutzomyia ovallesi in the Orinoco and Amazon River watersheds regions of Colombia, and the sympatric occurrence of Lutzomyia spinicrassa and Lutzomyia quasitownsendi in the eastern chain of the Andes mountains. Additionally, the municipal and altitudinal distributions are compiled for 19 new species recorded for Colombia. The series townsendi of the verrucarum group generally restricted to premontane and lower montane zones based on distribution data on Lutzomyia longiflocosa, L. quasitownsendi, Lutzomyia sauroida, L. spinicrassa, Lutzomyia torvida, Lutzomyia townsendi and Lutzomyia youngi. The series verrucarum is distributed from the tropical lowland to the montane zones, and includes species with wide geographical range (Lutzomyia evansi, Lutzomyia columbiana, L. ovallesi, Lutzomyia nuneztovari, Lutzomyia nevesi), and species of highly endemic distribution (Lutzomyia andina, Lutzomyia disiuncta, Lutzomyia moralesi, Lutzomyia antioquiensis). Members of the series pia (Lutzomyia pia, Lutzomyia limafalcaoae) and the series serrana (Lutzomyia serrana) occur from the tropical lowlands to the lower montane zones. The altitudinal divergences may be intrinsically tied to speciation process, especially as it relates to the climatic and geologic events that have affected the flora and fauna of the Andean region.

  17. [Geographical variation in the species Montivagum dihumerale and speciation in chigger mites (Acari: Trombiculidae)].

    PubMed

    Stekol'nikov, A A

    2006-01-01

    Intraspecific morphological variation of the chigger mite species Montivagum dihumerale (Traub et Nadchatram, 1967) is studied. Eco-geographic rules of the variation are revealed. General size of mites is found to be increased along with the rise of the high-mountain character of the landscape in the collection localities. The numbers of idiosomal setae are varied independently from the size parameters and geographically close populations are proved to be the most similar by these characters. At the same time, numbers of the setae of different types play the leading role in the discrimination of closely related Montivagum species, while the eco-geographical rules have not been found in this genus at the level of interspecific differences. As a result, the hypothesis is set up, that a significant degree of isolation of local populations separated from each other by high mountain ranges of the Central Asia is the main factor of speciation in the genus Montivagum. Regional character of this speciation mode is confirmed by the comparison with other chigger mites taxa.

  18. Geographic and Individual Differences in Healthcare Access for U.S. Transgender Adults: A Multilevel Analysis.

    PubMed

    White Hughto, Jaclyn M; Murchison, Gabriel R; Clark, Kirsty; Pachankis, John E; Reisner, Sari L

    2016-12-01

    To identify geographic and individual-level factors associated with healthcare access among transgender people in the United States. Multilevel analyses were conducted to investigate lifetime healthcare refusal using national data from 5831 U.S. transgender adults. Hierarchical generalized linear models examined associations between individual (age, gender, race, income, insurance, and healthcare avoidance) and state-level factors (percent voting Republican, percent same-sex couple households, income inequality, and transgender protective laws) and lifetime refusal of care. Results show that individual-level factors (being older; trans feminine; Native American, multiracial, or other racial/ethnic minority; having low income; and avoiding care due to discrimination) are positively associated with care refusal (all P-values <0.05). Adjusting for individual-level factors, variation was observed across U.S. states, with a greater proportion of states in the Southern and Western United States with transgender residents at increased odds of experiencing care refusal, relative to other regions of the United States. When adjusting for state-level factors, the percentage of the state population voting Republican was positively associated with care refusal among the transgender adults sampled (P < 0.01). Transgender adults surveyed reported differential access to healthcare by geographic region. Identifying geographic and individual-level factors associated with healthcare barriers allows for the development of targeted educational and policy interventions to improve healthcare access for transgender people most in need of services.

  19. Geographic and Individual Differences in Healthcare Access for U.S. Transgender Adults: A Multilevel Analysis

    PubMed Central

    Murchison, Gabriel R.; Clark, Kirsty; Pachankis, John E.; Reisner, Sari L.

    2016-01-01

    Abstract Purpose: To identify geographic and individual-level factors associated with healthcare access among transgender people in the United States. Methods: Multilevel analyses were conducted to investigate lifetime healthcare refusal using national data from 5831 U.S. transgender adults. Hierarchical generalized linear models examined associations between individual (age, gender, race, income, insurance, and healthcare avoidance) and state-level factors (percent voting Republican, percent same-sex couple households, income inequality, and transgender protective laws) and lifetime refusal of care. Results: Results show that individual-level factors (being older; trans feminine; Native American, multiracial, or other racial/ethnic minority; having low income; and avoiding care due to discrimination) are positively associated with care refusal (all P-values <0.05). Adjusting for individual-level factors, variation was observed across U.S. states, with a greater proportion of states in the Southern and Western United States with transgender residents at increased odds of experiencing care refusal, relative to other regions of the United States. When adjusting for state-level factors, the percentage of the state population voting Republican was positively associated with care refusal among the transgender adults sampled (P < 0.01). Conclusion: Transgender adults surveyed reported differential access to healthcare by geographic region. Identifying geographic and individual-level factors associated with healthcare barriers allows for the development of targeted educational and policy interventions to improve healthcare access for transgender people most in need of services. PMID:27636030

  20. Social Network Analysis and Qualitative Interviews for Assessing Geographic Characteristics of Tourism Business Networks.

    PubMed

    Kelman, Ilan; Luthe, Tobias; Wyss, Romano; Tørnblad, Silje H; Evers, Yvette; Curran, Marina Martin; Williams, Richard J; Berlow, Eric L

    2016-01-01

    This study integrates quantitative social network analysis (SNA) and qualitative interviews for understanding tourism business links in isolated communities through analysing spatial characteristics. Two case studies are used, the Surselva-Gotthard region in the Swiss Alps and Longyearbyen in the Arctic archipelago of Svalbard, to test the spatial characteristics of physical proximity, isolation, and smallness for understanding tourism business links. In the larger Surselva-Gotthard region, we found a strong relationship between geographic separation of the three communities on compartmentalization of the collaboration network. A small set of businesses played a central role in steering collaborative decisions for this community, while a group of structurally 'peripheral' actors were less influential. By contrast, the business community in Svalbard showed compartmentalization that was independent of geographic distance between actors. Within towns of similar size and governance scale, Svalbard is more compartmentalized, and those compartments are not driven by geographic separation of the collaboration clusters. This compartmentalization in Svalbard was reflected in a lower density of formal business collaboration ties compared to the communities of the Alps. We infer that the difference is due to Svalbard having higher cultural diversity and population turnover than the Alps communities. We propose that integrating quantitative network analysis from simple surveys with qualitative interviews targeted from the network results is an efficient general approach to identify regionally specific constraints and opportunities for effective governance.

  1. Updating a synchronous fluorescence spectroscopic virgin olive oil adulteration calibration to a new geographical region.

    PubMed

    Kunz, Matthew Ross; Ottaway, Joshua; Kalivas, John H; Georgiou, Constantinos A; Mousdis, George A

    2011-02-23

    Detecting and quantifying extra virgin olive adulteration is of great importance to the olive oil industry. Many spectroscopic methods in conjunction with multivariate analysis have been used to solve these issues. However, successes to date are limited as calibration models are built to a specific set of geographical regions, growing seasons, cultivars, and oil extraction methods (the composite primary condition). Samples from new geographical regions, growing seasons, etc. (secondary conditions) are not always correctly predicted by the primary model due to different olive oil and/or adulterant compositions stemming from secondary conditions not matching the primary conditions. Three Tikhonov regularization (TR) variants are used in this paper to allow adulterant (sunflower oil) concentration predictions in samples from geographical regions not part of the original primary calibration domain. Of the three TR variants, ridge regression with an additional 2-norm penalty provides the smallest validation sample prediction errors. Although the paper reports on using TR for model updating to predict adulterant oil concentration, the methods should also be applicable to updating models distinguishing adulterated samples from pure extra virgin olive oil. Additionally, the approaches are general and can be used with other spectroscopic methods and adulterants as well as with other agriculture products.

  2. Geographical Environment Factors and Risk Assessment of Tick-Borne Encephalitis in Hulunbuir, Northeastern China.

    PubMed

    Li, Yifan; Wang, Juanle; Gao, Mengxu; Fang, Liqun; Liu, Changhua; Lyu, Xin; Bai, Yongqing; Zhao, Qiang; Li, Hairong; Yu, Hongjie; Cao, Wuchun; Feng, Liqiang; Wang, Yanjun; Zhang, Bin

    2017-05-26

    Tick-borne encephalitis (TBE) is one of natural foci diseases transmitted by ticks. Its distribution and transmission are closely related to geographic and environmental factors. Identification of environmental determinates of TBE is of great importance to understanding the general distribution of existing and potential TBE natural foci. Hulunbuir, one of the most severe endemic areas of the disease, is selected as the study area. Statistical analysis, global and local spatial autocorrelation analysis, and regression methods were applied to detect the spatiotemporal characteristics, compare the impact degree of associated factors, and model the risk distribution using the heterogeneity. The statistical analysis of gridded geographic and environmental factors and TBE incidence show that the TBE patients mainly occurred during spring and summer and that there is a significant positive spatial autocorrelation between the distribution of TBE cases and environmental characteristics. The impact degree of these factors on TBE risks has the following descending order: temperature, relative humidity, vegetation coverage, precipitation and topography. A high-risk area with a triangle shape was determined in the central part of Hulunbuir; the low-risk area is located in the two belts next to the outside edge of the central triangle. The TBE risk distribution revealed that the impact of the geographic factors changed depending on the heterogeneity.

  3. Genetic Diversity and Geographical Distribution of Indigenous Soybean-Nodulating Bradyrhizobia in the United States

    PubMed Central

    Shiro, Sokichi; Matsuura, Syota; Saiki, Rina; Sigua, Gilbert C.; Yamamoto, Akihiro; Umehara, Yosuke; Hayashi, Masaki

    2013-01-01

    We investigated the relationship between the genetic diversity of indigenous soybean-nodulating bradyrhizobia and their geographical distribution in the United States using nine soil isolates from eight states. The bradyrhizobia were inoculated on three soybean Rj genotypes (non-Rj, Rj2Rj3, and Rj4). We analyzed their genetic diversity and community structure by means of restriction fragment length polymorphisms of PCR amplicons to target the 16S-23S rRNA gene internal transcribed spacer region, using 11 USDA Bradyrhizobium strains as reference strains. We also performed diversity analysis, multidimensional scaling analysis based on the Bray-Curtis index, and polar ordination analysis to describe the structure and geographical distribution of the soybean-nodulating bradyrhizobial community. The major clusters were Bradyrhizobium japonicum Bj123, in the northern United States, and Bradyrhizobium elkanii, in the middle to southern regions. Dominance of bradyrhizobia in a community was generally larger for the cluster belonging to B. elkanii than for the cluster belonging to B. japonicum. The indigenous American soybean-nodulating bradyrhizobial community structure was strongly correlated with latitude. Our results suggest that this community varies geographically. PMID:23563944

  4. Social Network Analysis and Qualitative Interviews for Assessing Geographic Characteristics of Tourism Business Networks

    PubMed Central

    Luthe, Tobias; Wyss, Romano; Tørnblad, Silje H.; Evers, Yvette; Curran, Marina Martin; Williams, Richard J.; Berlow, Eric L.

    2016-01-01

    This study integrates quantitative social network analysis (SNA) and qualitative interviews for understanding tourism business links in isolated communities through analysing spatial characteristics. Two case studies are used, the Surselva-Gotthard region in the Swiss Alps and Longyearbyen in the Arctic archipelago of Svalbard, to test the spatial characteristics of physical proximity, isolation, and smallness for understanding tourism business links. In the larger Surselva-Gotthard region, we found a strong relationship between geographic separation of the three communities on compartmentalization of the collaboration network. A small set of businesses played a central role in steering collaborative decisions for this community, while a group of structurally ‘peripheral’ actors were less influential. By contrast, the business community in Svalbard showed compartmentalization that was independent of geographic distance between actors. Within towns of similar size and governance scale, Svalbard is more compartmentalized, and those compartments are not driven by geographic separation of the collaboration clusters. This compartmentalization in Svalbard was reflected in a lower density of formal business collaboration ties compared to the communities of the Alps. We infer that the difference is due to Svalbard having higher cultural diversity and population turnover than the Alps communities. We propose that integrating quantitative network analysis from simple surveys with qualitative interviews targeted from the network results is an efficient general approach to identify regionally specific constraints and opportunities for effective governance. PMID:27258007

  5. DNA barcoding gap: reliable species identification over morphological and geographical scales.

    PubMed

    Čandek, Klemen; Kuntner, Matjaž

    2015-03-01

    The philosophical basis and utility of DNA barcoding have been a subject of numerous debates. While most literature embraces it, some studies continue to question its use in dipterans, butterflies and marine gastropods. Here, we explore the utility of DNA barcoding in identifying spider species that vary in taxonomic affiliation, morphological diagnosibility and geographic distribution. Our first test searched for a 'barcoding gap' by comparing intra- and interspecific means, medians and overlap in more than 75,000 computed Kimura 2-parameter (K2P) genetic distances in three families. Our second test compared K2P distances of congeneric species with high vs. low morphological distinctness in 20 genera of 11 families. Our third test explored the effect of enlarging geographical sampling area at a continental scale on genetic variability in DNA barcodes within 20 species of nine families. Our results generally point towards a high utility of DNA barcodes in identifying spider species. However, the size of the barcoding gap strongly depends on taxonomic groups and practices. It is becoming critical to define the barcoding gap statistically more consistently and to document its variation over taxonomic scales. Our results support models of independent patterns of morphological and molecular evolution by showing that DNA barcodes are effective in species identification regardless of their morphological diagnosibility. We also show that DNA barcodes represent an effective tool for identifying spider species over geographic scales, yet their variation contains useful biogeographic information. © 2014 John Wiley & Sons Ltd.

  6. Geographical Text Analysis: A new approach to understanding nineteenth-century mortality.

    PubMed

    Porter, Catherine; Atkinson, Paul; Gregory, Ian

    2015-11-01

    This paper uses a combination of Geographic Information Systems (GIS) and corpus linguistic analysis to extract and analyse disease related keywords from the Registrar-General's Decennial Supplements. Combined with known mortality figures, this provides, for the first time, a spatial picture of the relationship between the Registrar-General's discussion of disease and deaths in England and Wales in the nineteenth and early twentieth centuries. Techniques such as collocation, density analysis, the Hierarchical Regional Settlement matrix and regression analysis are employed to extract and analyse the data resulting in new insight into the relationship between the Registrar-General's published texts and the changing mortality patterns during this time. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Geodata Modeling and Query in Geographic Information Systems

    NASA Technical Reports Server (NTRS)

    Adam, Nabil

    1996-01-01

    Geographic information systems (GIS) deal with collecting, modeling, man- aging, analyzing, and integrating spatial (locational) and non-spatial (attribute) data required for geographic applications. Examples of spatial data are digital maps, administrative boundaries, road networks, and those of non-spatial data are census counts, land elevations and soil characteristics. GIS shares common areas with a number of other disciplines such as computer- aided design, computer cartography, database management, and remote sensing. None of these disciplines however, can by themselves fully meet the requirements of a GIS application. Examples of such requirements include: the ability to use locational data to produce high quality plots, perform complex operations such as network analysis, enable spatial searching and overlay operations, support spatial analysis and modeling, and provide data management functions such as efficient storage, retrieval, and modification of large datasets; independence, integrity, and security of data; and concurrent access to multiple users. It is on the data management issues that we devote our discussions in this monograph. Traditionally, database management technology have been developed for business applications. Such applications require, among other things, capturing the data requirements of high-level business functions and developing machine- level implementations; supporting multiple views of data and yet providing integration that would minimize redundancy and maintain data integrity and security; providing a high-level language for data definition and manipulation; allowing concurrent access to multiple users; and processing user transactions in an efficient manner. The demands on database management systems have been for speed, reliability, efficiency, cost effectiveness, and user-friendliness. Significant progress have been made in all of these areas over the last two decades to the point that many generalized database platforms

  8. Teaching geographical hydrology in a non-stationary world

    NASA Astrophysics Data System (ADS)

    Hendriks, Martin R.; Karssenberg, Derek

    2010-05-01

    Understanding hydrological processes in a non-stationary world requires knowledge of hydrological processes and their interactions. Also, one needs to understand the (non-linear) relations between the hydrological system and other parts of our Earth system, such as the climate system, the socio-economic system, and the ecosystem. To provide this knowledge and understanding we think that three components are essential when teaching geographical hydrology. First of all, a student needs to acquire a thorough understanding of classical hydrology. For this, knowledge of the basic hydrological equations, such as the energy equation (Bernoulli), flow equation (Darcy), continuity (or water balance) equation is needed. This, however, is not sufficient to make a student fully understand the interactions between hydrological compartments, or between hydrological subsystems and other parts of the Earth system. Therefore, secondly, a student also needs to be knowledgeable of methods by which the different subsystems can be coupled; in general, numerical models are used for this. A major disadvantage of numerical models is their complexity. A solution may be to use simpler models, provided that a student really understands how hydrological processes function in our real, non-stationary world. The challenge for a student then lies in understanding the interactions between the subsystems, and to be able to answer questions such as: what is the effect of a change in vegetation or land use on runoff? Thirdly, knowledge of field hydrology is of utmost importance. For this a student needs to be trained in the field. Fieldwork is very important as a student is confronted in the field with spatial and temporal variability, as well as with real life uncertainties, rather than being lured into believing the world as presented in hydrological textbooks and models, e.g. the world under study is homogeneous, isotropic, or lumped (averaged). Also, students in the field learn to plan and

  9. A preliminary geodetic data model for geographic information systems

    NASA Astrophysics Data System (ADS)

    Kelly, K. M.

    2009-12-01

    Our ability to gather and assimilate integrated data collections from multiple disciplines is important for earth system studies. Moreover, geosciences data collection has increased dramatically, with pervasive networks of observational stations on the ground, in the oceans, in the atmosphere and in space. Contemporary geodetic observations from several space and terrestrial technologies contribute to our knowledge of earth system processes and thus are a valuable source of high accuracy information for many global change studies. Assimilation of these geodetic observations and numerical models into models of weather, climate, oceans, hydrology, ice, and solid Earth processes is an important contribution geodesists can make to the earth science community. Clearly, the geodetic observations and models are fundamental to these contributions. ESRI wishes to provide leadership in the geodetic community to collaboratively build an open, freely available content specification that can be used by anyone to structure and manage geodetic data. This Geodetic Data Model will provide important context for all geographic information. The production of a task-specific geodetic data model involves several steps. The goal of the data model is to provide useful data structures and best practices for each step, making it easier for geodesists to organize their data and metadata in a way that will be useful in their data analyses and to their customers. Built on concepts from the successful Arc Marine data model, we introduce common geodetic data types and summarize the main thematic layers of the Geodetic Data Model. These provide a general framework for envisioning the core feature classes required to represent geodetic data in a geographic information system. Like Arc Marine, the framework is generic to allow users to build workflow or product specific geodetic data models tailored to the specific task(s) at hand. This approach allows integration of the data with other existing

  10. Quick multitemporal approach to get cloudless improved multispectral imagery for large geographical areas

    NASA Astrophysics Data System (ADS)

    Colaninno, Nicola; Marambio Castillo, Alejandro; Roca Cladera, Josep

    2017-10-01

    The demand for remotely sensed data is growing increasingly, due to the possibility of managing information about huge geographic areas, in digital format, at different time periods, and suitable for analysis in GIS platforms. However, primary satellite information is not such immediate as desirable. Beside geometric and atmospheric limitations, clouds, cloud shadows, and haze generally contaminate optical images. In terms of land cover, such a contamination is intended as missing information and should be replaced. Generally, image reconstruction is classified according to three main approaches, i.e. in-painting-based, multispectral-based, and multitemporal-based methods. This work relies on a multitemporal-based approach to retrieve uncontaminated pixels for an image scene. We explore an automatic method for quickly getting daytime cloudless and shadow-free image at moderate spatial resolution for large geographical areas. The process expects two main steps: a multitemporal effect adjustment to avoid significant seasonal variations, and a data reconstruction phase, based on automatic selection of uncontaminated pixels from an image stack. The result is a composite image based on middle values of the stack, over a year. The assumption is that, for specific purposes, land cover changes at a coarse scale are not significant over relatively short time periods. Because it is largely recognized that satellite imagery along tropical areas are generally strongly affected by clouds, the methodology is tested for the case study of the Dominican Republic at the year 2015; while Landsat 8 imagery are employed to test the approach.

  11. Forest management applications of Landsat data in a geographic information system

    NASA Technical Reports Server (NTRS)

    Maw, K. D.; Brass, J. A.

    1982-01-01

    The utility of land-cover data resulting from Landsat MSS classification can be greatly enhanced by use in combination with ancillary data. A demonstration forest management applications data base was constructed for Santa Cruz County, California, to demonstrate geographic information system applications of classified Landsat data. The data base contained detailed soils, digital terrain, land ownership, jurisdictional boundaries, fire events, and generalized land-use data, all registered to a UTM grid base. Applications models were developed from problems typical of fire management and reforestation planning.

  12. The effect of geographical indices on left ventricular structure in healthy Han Chinese population.

    PubMed

    Cen, Minyi; Ge, Miao; Liu, Yonglin; Wang, Congxia; Yang, Shaofang

    2017-02-01

    The left ventricular posterior wall thickness (LVPWT) and interventricular septum thickness (IVST) are generally regarded as the functional parts of the left ventricular (LV) structure. This paper aims to examine the effects of geographical indices on healthy Han adults' LV structural indices and to offer a scientific basis for developing a unified standard for the reference values of adults' LV structural indices in China. Fifteen terrain, climate, and soil indices were examined as geographical explanatory variables. Statistical analysis was performed using correlation analysis. Moreover, a back propagation neural network (BPNN) and a support vector regression (SVR) were applied to developing models to predict the values of two indices. After the prediction models were built, distribution maps were produced. The results show that LV structural indices are characteristically associated with latitude, longitude, altitude, average temperature, average wind velocity, topsoil sand fraction, topsoil silt fraction, topsoil organic carbon, and topsoil sodicity. The model test analyses show the BPNN model possesses better simulative and predictive ability in comparison with the SVR model. The distribution maps of the LV structural indices show that, in China, the values are higher in the west and lower in the east. These results demonstrate that the reference values of the adults' LV structural indices will be different affected by different geographical environment. The reference values of LV structural indices in one region can be calculated by setting up a BPNN, which showed better applicability in this study. The distribution of the reference values of the LV structural indices can be seen clearly on the geographical distribution map.

  13. Climate change influences on the potential geographic distribution of the disease vector tick Ixodes ricinus

    PubMed Central

    Peterson, A. Townsend; Samy, Abdallah M.

    2017-01-01

    Background Ixodes ricinus is a species of hard tick that transmits several important diseases in Europe and North Africa, including Lyme borreliosis and tick-borne encephalitis. Climate change is affecting the geographic distributions and abundances of arthropod vectors, which in turn influence the geographic distribution and epidemiology of associated vector-borne diseases. To date, few studies have investigated effects of climate change on the spatial distribution of I. ricinus at continental extents. Here, we assessed the potential distribution of I. ricinus under current and future climate conditions to understand how climate change will influence the geographic distribution of this important tick vector in coming decades. Method We used ecological niche modeling to estimate the geographic distribution of I. ricinus with respect to current climate, and then assessed its future potential distribution under different climate change scenarios. This approach integrates occurrence records of I. ricinus with six relevant environmental variables over a continental extent that includes Europe, North Africa, and the Middle East. Future projections were based on climate data from 17 general circulation models (GCMs) under 2 representative concentration pathway emissions scenarios (RCPs), for the years 2050 and 2070. Result The present and future potential distributions of I. ricinus showed broad overlap across most of western and central Europe, and in more narrow zones in eastern and northern Europe, and North Africa. Potential expansions were observed in northern and eastern Europe. These results indicate that I. ricinus populations could emerge in areas in which they are currently lacking, posing increased risks to human health in those areas. However, the future of I. ricinus ticks in some important regions such the Mediterranean was unclear owing to high uncertainty in model predictions. PMID:29206879

  14. The effect of geographical indices on left ventricular structure in healthy Han Chinese population

    NASA Astrophysics Data System (ADS)

    Cen, Minyi; Ge, Miao; Liu, Yonglin; Wang, Congxia; Yang, Shaofang

    2017-02-01

    The left ventricular posterior wall thickness (LVPWT) and interventricular septum thickness (IVST) are generally regarded as the functional parts of the left ventricular (LV) structure. This paper aims to examine the effects of geographical indices on healthy Han adults' LV structural indices and to offer a scientific basis for developing a unified standard for the reference values of adults' LV structural indices in China. Fifteen terrain, climate, and soil indices were examined as geographical explanatory variables. Statistical analysis was performed using correlation analysis. Moreover, a back propagation neural network (BPNN) and a support vector regression (SVR) were applied to developing models to predict the values of two indices. After the prediction models were built, distribution maps were produced. The results show that LV structural indices are characteristically associated with latitude, longitude, altitude, average temperature, average wind velocity, topsoil sand fraction, topsoil silt fraction, topsoil organic carbon, and topsoil sodicity. The model test analyses show the BPNN model possesses better simulative and predictive ability in comparison with the SVR model. The distribution maps of the LV structural indices show that, in China, the values are higher in the west and lower in the east. These results demonstrate that the reference values of the adults' LV structural indices will be different affected by different geographical environment. The reference values of LV structural indices in one region can be calculated by setting up a BPNN, which showed better applicability in this study. The distribution of the reference values of the LV structural indices can be seen clearly on the geographical distribution map.

  15. Climate change influences on the potential geographic distribution of the disease vector tick Ixodes ricinus.

    PubMed

    Alkishe, Abdelghafar A; Peterson, A Townsend; Samy, Abdallah M

    2017-01-01

    Ixodes ricinus is a species of hard tick that transmits several important diseases in Europe and North Africa, including Lyme borreliosis and tick-borne encephalitis. Climate change is affecting the geographic distributions and abundances of arthropod vectors, which in turn influence the geographic distribution and epidemiology of associated vector-borne diseases. To date, few studies have investigated effects of climate change on the spatial distribution of I. ricinus at continental extents. Here, we assessed the potential distribution of I. ricinus under current and future climate conditions to understand how climate change will influence the geographic distribution of this important tick vector in coming decades. We used ecological niche modeling to estimate the geographic distribution of I. ricinus with respect to current climate, and then assessed its future potential distribution under different climate change scenarios. This approach integrates occurrence records of I. ricinus with six relevant environmental variables over a continental extent that includes Europe, North Africa, and the Middle East. Future projections were based on climate data from 17 general circulation models (GCMs) under 2 representative concentration pathway emissions scenarios (RCPs), for the years 2050 and 2070. The present and future potential distributions of I. ricinus showed broad overlap across most of western and central Europe, and in more narrow zones in eastern and northern Europe, and North Africa. Potential expansions were observed in northern and eastern Europe. These results indicate that I. ricinus populations could emerge in areas in which they are currently lacking, posing increased risks to human health in those areas. However, the future of I. ricinus ticks in some important regions such the Mediterranean was unclear owing to high uncertainty in model predictions.

  16. Geographic patterns of seed mass are associated with climate factors, but relationships vary between species.

    PubMed

    Soper Gorden, Nicole L; Winkler, Katharine J; Jahnke, Matthew R; Marshall, Elizabeth; Horky, Joshua; Huddelson, Colton; Etterson, Julie R

    2016-01-01

    Seed size is a critical life history attribute with fitness effects that cascade throughout the lifespan of plants. Interspecific studies repeatedly report a negative correlation between seed mass and latitude. Yet, despite its importance, little is known about geographic variation in seed size within species' ranges. To improve our understanding of intraspecific geographic variation in seed size, we collected and weighed seeds by maternal line from 8 to 17 populations of seven herbaceous plant species spanning large geographic areas, and measured a dispersal trait, awn length, for two grass species. We examined the overall relationship between seed mass and latitude, then divided the data into species-specific subsets to compare the fit of three models to explain seed mass and awn length: (1) latitude and longitude, (2) long-term climate, and (3) collection-year weather. Like previous work, we found a negative relationship between interspecific seed mass and latitude. However, the best-fit models explaining seed size and awn length differed between individual species and often included significant interaction terms. For all species, the best model was either long-term or collection-year climate data instead of latitude and longitude. Intraspecific geographic patterns for seed traits were remarkably inconsistent, covarying both negatively and positively with temperature and precipitation. The only apparent generalization is that annual species' seed mass corresponded more with collection-year weather while perennial species covaried more with long-term climate. Overall, this study suggests that the scale of climate variation that molds seed traits is highly species-specific. © 2016 Botanical Society of America.

  17. Sirenomelia in Argentina: Prevalence, geographic clusters and temporal trends analysis.

    PubMed

    Groisman, Boris; Liascovich, Rosa; Gili, Juan Antonio; Barbero, Pablo; Bidondo, María Paz

    2016-07-01

    Sirenomelia is a severe malformation of the lower body characterized by a single medial lower limb and a variable combination of visceral abnormalities. Given that Sirenomelia is a very rare birth defect, epidemiological studies are scarce. The aim of this study is to evaluate prevalence, geographic clusters and time trends of sirenomelia in Argentina, using data from the National Network of Congenital Anomalies of Argentina (RENAC) from November 2009 until December 2014. This is a descriptive study using data from the RENAC, a hospital-based surveillance system for newborns affected with major morphological congenital anomalies. We calculated sirenomelia prevalence throughout the period, searched for geographical clusters, and evaluated time trends. The prevalence of confirmed cases of sirenomelia throughout the period was 2.35 per 100,000 births. Cluster analysis showed no statistically significant geographical aggregates. Time-trends analysis showed that the prevalence was higher in years 2009 to 2010. The observed prevalence was higher than the observed in previous epidemiological studies in other geographic regions. We observed a likely real increase in the initial period of our study. We used strict diagnostic criteria, excluding cases that only had clinical diagnosis of sirenomelia. Therefore, real prevalence could be even higher. This study did not show any geographic clusters. Because etiology of sirenomelia has not yet been established, studies of epidemiological features of this defect may contribute to define its causes. Birth Defects Research (Part A) 106:604-611, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  18. 20. Raw Material for the Geographic Magazine. The mills of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Raw Material for the Geographic Magazine. The mills of the Champion International Company which make paper on which the National Geographic Magazine is printed are located in Lawrence, Mass. This picture shows great piles of pulp-wood ready for conversion into paper for the The Geographic. Parts of these wood piles are more than 50 feet high. The cars shown in the picture are on a trestle 21 feet high. The Geographic magazines mailed in a single year, if laid side by side, would reach from Quito, Ecuador, across Colombia and Caribbean, thence across the United States and Canada, through the North Pole, and across Siberia, China, and Siam to Bangkok. It takes 33,000 miles of wrappers to mail one year's edition. It would require a bookshelf more than three and a half miles long to hold all the copies of this month's issue of The Geographic. (p.235.) - Champion-International Paper Company, West bank of Spicket River at Canal Street, Lawrence, Essex County, MA

  19. Research on a Method of Geographical Information Service Load Balancing

    NASA Astrophysics Data System (ADS)

    Li, Heyuan; Li, Yongxing; Xue, Zhiyong; Feng, Tao

    2018-05-01

    With the development of geographical information service technologies, how to achieve the intelligent scheduling and high concurrent access of geographical information service resources based on load balancing is a focal point of current study. This paper presents an algorithm of dynamic load balancing. In the algorithm, types of geographical information service are matched with the corresponding server group, then the RED algorithm is combined with the method of double threshold effectively to judge the load state of serve node, finally the service is scheduled based on weighted probabilistic in a certain period. At the last, an experiment system is built based on cluster server, which proves the effectiveness of the method presented in this paper.

  20. Fast, Inclusive Searches for Geographic Names Using Digraphs

    USGS Publications Warehouse

    Donato, David I.

    2008-01-01

    An algorithm specifies how to quickly identify names that approximately match any specified name when searching a list or database of geographic names. Based on comparisons of the digraphs (ordered letter pairs) contained in geographic names, this algorithmic technique identifies approximately matching names by applying an artificial but useful measure of name similarity. A digraph index enables computer name searches that are carried out using this technique to be fast enough for deployment in a Web application. This technique, which is a member of the class of n-gram algorithms, is related to, but distinct from, the soundex, PHONIX, and metaphone phonetic algorithms. Despite this technique's tendency to return some counterintuitive approximate matches, it is an effective aid for fast, inclusive searches for geographic names when the exact name sought, or its correct spelling, is unknown.