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Sample records for fine-scale species segregation

  1. Fine-scale species associations in alvar limestone grasslands

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    Diekmann, M; Dupre, C; van der Maarel, E

    2004-01-01

    To examine the importance of positive or negative interactions of plant species on a micro-scale, species associations were studied in 38 1 m(2) - plots in alvar limestone grasslands on Oland, Sweden. Each plot was assumed to be homogeneous as to its environmental conditions and spatial distribution

  2. Fine-scale urbanization affects Odonata species diversity in ponds of a megacity (Paris, France)

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    Jeanmougin, Martin; Leprieur, Fabien; Loïs, Grégoire; Clergeau, Philippe

    2014-08-01

    Current developments in urban ecology include very few studies focused on pond ecosystems, though ponds are recognized as biodiversity hotspots. Using Odonata as an indicator model, we explored changes in species composition in ponds localized along an urban gradient of a megacity (Paris, France). We then assessed the relative importance of local- and landscape-scale variables in shaping Odonata α-diversity patterns using a model-averaging approach. Analyses were performed for adult (A) and adult plus exuviae (AE) census data. At 26 ponds, we recorded 657 adults and 815 exuviae belonging to 17 Odonata species. The results showed that the Odonata species assemblage composition was not determined by pond localization along the urban gradient. Similarly, pond characteristics were found to be similar among urban, suburban and periurban ponds. The analyses of AE census data revealed that fine-scale urbanization (i.e., increased density of buildings surrounding ponds) negatively affects Odonata α-diversity. In contrast, pond localization along the urban gradient weakly explained the α-diversity patterns. Several local-scale variables, such as the coverage of submerged macrophytes, were found to be significant drivers of Odonata α-diversity. Together, these results show that the degree of urbanization around ponds must be considered instead of pond localization along the urban gradient when assessing the potential impacts of urbanization on Odonata species diversity. This work also indicates the importance of exuviae sampling in understanding the response of Odonata to urbanization.

  3. Modeling plant species distributions under future climates: how fine scale do climate projections need to be?

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    Franklin, Janet; Davis, Frank W; Ikegami, Makihiko; Syphard, Alexandra D; Flint, Lorraine E; Flint, Alan L; Hannah, Lee

    2013-02-01

    Recent studies suggest that species distribution models (SDMs) based on fine-scale climate data may provide markedly different estimates of climate-change impacts than coarse-scale models. However, these studies disagree in their conclusions of how scale influences projected species distributions. In rugged terrain, coarse-scale climate grids may not capture topographically controlled climate variation at the scale that constitutes microhabitat or refugia for some species. Although finer scale data are therefore considered to better reflect climatic conditions experienced by species, there have been few formal analyses of how modeled distributions differ with scale. We modeled distributions for 52 plant species endemic to the California Floristic Province of different life forms and range sizes under recent and future climate across a 2000-fold range of spatial scales (0.008-16 km(2) ). We produced unique current and future climate datasets by separately downscaling 4 km climate models to three finer resolutions based on 800, 270, and 90 m digital elevation models and deriving bioclimatic predictors from them. As climate-data resolution became coarser, SDMs predicted larger habitat area with diminishing spatial congruence between fine- and coarse-scale predictions. These trends were most pronounced at the coarsest resolutions and depended on climate scenario and species' range size. On average, SDMs projected onto 4 km climate data predicted 42% more stable habitat (the amount of spatial overlap between predicted current and future climatically suitable habitat) compared with 800 m data. We found only modest agreement between areas predicted to be stable by 90 m models generalized to 4 km grids compared with areas classified as stable based on 4 km models, suggesting that some climate refugia captured at finer scales may be missed using coarser scale data. These differences in projected locations of habitat change may have more serious implications than net

  4. Predicting fine-scale distributions of peripheral aquatic species in headwater streams

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    DeRolph, Christopher R.; Nelson, S.; Kwak, Thomas J.; Hain, Ernie F.

    2015-01-01

    Headwater species and peripheral populations that occupy habitat at the edge of a species range may hold an increased conservation value to managers due to their potential to maximize intraspecies diversity and species' adaptive capabilities in the context of rapid environmental change. The southern Appalachian Mountains are the southern extent of the geographic range of native Salvelinus fontinalis and naturalized Oncorhynchus mykiss and Salmo trutta in eastern North America. We predicted distributions of these peripheral, headwater wild trout populations at a fine scale to serve as a planning and management tool for resource managers to maximize resistance and resilience of these populations in the face of anthropogenic stressors. We developed correlative logistic regression models to predict occurrence of brook trout, rainbow trout, and brown trout for every interconfluence stream reach in the study area. A stream network was generated to capture a more consistent representation of headwater streams. Each of the final models had four significant metrics in common: stream order, fragmentation, precipitation, and land cover. Strahler stream order was found to be the most influential variable in two of the three final models and the second most influential variable in the other model. Greater than 70% presence accuracy was achieved for all three models. The underrepresentation of headwater streams in commonly used hydrography datasets is an important consideration that warrants close examination when forecasting headwater species distributions and range estimates. Additionally, it appears that a relative watershed position metric (e.g., stream order) is an important surrogate variable (even when elevation is included) for biotic interactions across the landscape in areas where headwater species distributions are influenced by topographical gradients.

  5. Evaluation of Species Distribution Model Algorithms For Fine-Scale Container Breeding Mosquito Risk Prediction

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    Khatchikian, C.; Sangermano, F.; Kendell, D.; Livdahl, T.

    2010-01-01

    The present work evaluates the use of species distribution model (SDM) algorithms to classify high density of small container Aedes mosquitoes at a fine scale, in the Bermuda islands. Weekly ovitrap data collected by the Health Department of Bermuda (UK) for the years 2006 and 2007 were used for the models. The models evaluated included the following algorithms: Bioclim, Domain, GARP, logistic regression, and MaxEnt. Models were evaluated according to performance and robustness. The area Receiver Operating Characteristic (ROC) curve was used to evaluate each model’s performance, and robustness was assessed considering the spatial correlation between classification risks for the two datasets. Relative to the other algorithms, logistic regression was the best model for classifying high risk areas, and the maximum entropy approach (MaxEnt) presented the second best performance. We report the importance of covariables for these two models, and discuss the utility of SDMs for vector control efforts and the potential for the development of scripts that automate the task of creating risk assessment maps. PMID:21198711

  6. Fine-scale spatial variation in plant species richness and its relationship to environmental conditions in coastal marshlands

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    Mancera, J.E.; Meche, G.C.; Cardona-Olarte, P.P.; Castaneda-Moya, E.; Chiasson, R.L.; Geddes, N.A.; Schile, L.M.; Wang, H.G.; Guntenspergen, G.R.; Grace, J.B.

    2005-01-01

    Previous studies have shown that variations in environmental conditions play a major role in explaining variations in plant species richness at community and landscape scales. In this study, we considered the degree to which fine-scale spatial variations in richness could be related to fine-scale variations in abiotic and biotic factors. To examine spatial variation in richness, grids of 1 m(2) plots were laid out at five sites within a coastal riverine wetland landscape. At each site, a 5 x 7 array of plots was established adjacent to the river's edge with plots one meter apart. In addition to the estimation of species richness, environmental measurements included sediment salinity, plot microelevation, percent of plot recently disturbed, and estimated community biomass. Our analysis strategy was to combine the use of structural equation modeling (path modeling) with an assessment of spatial association. Mantel's tests revealed significant spatial autocorrelation in species richness at four of the five sites sampled, indicating that richness in a plot correlated with the richness of nearby plots. We subsequently considered the degree to which spatial autocorrelations in richness could be explained by spatial autocorrelations in environmental conditions. Once data were corrected for environmental correlations, spatial autocorrelation in residual species richness could not be detected at any site. Based on these results, we conclude that in this coastal wetland, there appears to be a fine-scale mapping of diversity to microgradients in environmental conditions.

  7. Evaluating β Diversity as a Surrogate for Species Representation at Fine Scale.

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    Paul Beier

    Full Text Available Species turnover or β diversity is a conceptually attractive surrogate for conservation planning. However, there has been only 1 attempt to determine how well sites selected to maximize β diversity represent species, and that test was done at a scale too coarse (2,500 km2 sites to inform most conservation decisions. We used 8 plant datasets, 3 bird datasets, and 1 mammal dataset to evaluate whether sites selected to span β diversity will efficiently represent species at finer scale (sites sizes < 1 ha to 625 km2. We used ordinations to characterize dissimilarity in species assemblages (β diversity among plots (inventory data or among grid cells (atlas data. We then selected sites to maximize β diversity and used the Species Accumulation Index, SAI, to evaluate how efficiently the surrogate (selecting sites for maximum β diversity represented species in the same taxon. Across all 12 datasets, sites selected for maximum β diversity represented species with a median efficiency of 24% (i.e., the surrogate was 24% more effective than random selection of sites, and an interquartile range of 4% to 41% efficiency. β diversity was a better surrogate for bird datasets than for plant datasets, and for atlas datasets with 10-km to 14-km grid cells than for atlas datasets with 25-km grid cells. We conclude that β diversity is more than a mere descriptor of how species are distributed on the landscape; in particular β diversity might be useful to maximize the complementarity of a set of sites. Because we tested only within-taxon surrogacy, our results do not prove that β diversity is useful for conservation planning. But our results do justify further investigation to identify the circumstances in which β diversity performs well, and to evaluate it as a cross-taxon surrogate.

  8. Fine scale spatial genetic structure in Pouteria reticulata (Engl. Eyma (Sapotaceae, a dioecious, vertebrate dispersed tropical rain forest tree species

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    John W. Schroeder

    2014-08-01

    Full Text Available Dioecious tropical tree species often have small flowers and fleshy fruits indicative of small-insect pollination and vertebrate seed dispersal. We hypothesize that seed mediated gene flow should be exceed pollen-mediated gene flow in such species, leading to weak patterns of fine scale spatial genetic structure (SGS. In the present study, we characterize novel microsatellite DNA markers and test for SGS in sapling (N=100 and adult trees (N=99 of the dioecious canopy tree Pouteria reticulata (Sapotaceae in a 50 ha forest dynamics plot on Barro Colorado Island (BCI, Panama. The five genetic markers contained between five and 15 alleles per locus, totaling 51 alleles in the sample population. Significant SGS at local spatial scales (<100m was detected in the sapling (dbh≈1cm and adult (dbh≥20cm size classes, but was stronger in the former (sapling Sp=0.010±0.004, adult Sp=0.006±0.002, suggesting demographic thinning. The degree of SGS was lower than the value expected for non-vertebrate dispersed tropical trees (Sp=0.029, but similar to the average value for vertebrate dispersed tropical trees (Sp=0.009 affirming the dispersal potential of vertebrate dispersed tropical trees in faunally intact forests.

  9. Fine-Scale Ecological and Genetic Population Structure of Two Whitefish (Coregoninae) Species in the Vicinity of Industrial Thermal Emissions.

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    Graham, Carly F; Eberts, Rebecca L; Morgan, Thomas D; Boreham, Douglas R; Lance, Stacey L; Manzon, Richard G; Martino, Jessica A; Rogers, Sean M; Wilson, Joanna Y; Somers, Christopher M

    2016-01-01

    Thermal pollution from industrial processes can have negative impacts on the spawning and development of cold-water fish. Point sources of thermal effluent may need to be managed to avoid affecting discrete populations. Correspondingly, we examined fine-scale ecological and genetic population structure of two whitefish species (Coregonus clupeaformis and Prosopium cylindraceum) on Lake Huron, Canada, in the immediate vicinity of thermal effluent from nuclear power generation. Niche metrics using δ13C and δ15N stable isotopes showed high levels of overlap (48.6 to 94.5%) in resource use by adult fish captured in areas affected by thermal effluent compared to nearby reference locations. Isotopic niche size, a metric of resource use diversity, was 1.3- to 2.8-fold higher than reference values in some thermally affected areas, indicative of fish mixing. Microsatellite analyses of genetic population structure (Fst, STRUCTURE and DAPC) indicated that fish captured at all locations in the vicinity of the power plant were part of a larger population extending beyond the study area. In concert, ecological and genetic markers do not support the presence of an evolutionarily significant unit in the vicinity of the power plant. Thus, future research should focus on the potential impacts of thermal emissions on development and recruitment.

  10. Fine-Scale Ecological and Genetic Population Structure of Two Whitefish (Coregoninae Species in the Vicinity of Industrial Thermal Emissions.

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    Carly F Graham

    Full Text Available Thermal pollution from industrial processes can have negative impacts on the spawning and development of cold-water fish. Point sources of thermal effluent may need to be managed to avoid affecting discrete populations. Correspondingly, we examined fine-scale ecological and genetic population structure of two whitefish species (Coregonus clupeaformis and Prosopium cylindraceum on Lake Huron, Canada, in the immediate vicinity of thermal effluent from nuclear power generation. Niche metrics using δ13C and δ15N stable isotopes showed high levels of overlap (48.6 to 94.5% in resource use by adult fish captured in areas affected by thermal effluent compared to nearby reference locations. Isotopic niche size, a metric of resource use diversity, was 1.3- to 2.8-fold higher than reference values in some thermally affected areas, indicative of fish mixing. Microsatellite analyses of genetic population structure (Fst, STRUCTURE and DAPC indicated that fish captured at all locations in the vicinity of the power plant were part of a larger population extending beyond the study area. In concert, ecological and genetic markers do not support the presence of an evolutionarily significant unit in the vicinity of the power plant. Thus, future research should focus on the potential impacts of thermal emissions on development and recruitment.

  11. RAD genotyping reveals fine-scale genetic structuring and provides powerful population assignment in a widely distributed marine species, the American lobster (Homarus americanus).

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    Benestan, Laura; Gosselin, Thierry; Perrier, Charles; Sainte-Marie, Bernard; Rochette, Rémy; Bernatchez, Louis

    2015-07-01

    Deciphering genetic structure and inferring connectivity in marine species have been challenging due to weak genetic differentiation and limited resolution offered by traditional genotypic methods. The main goal of this study was to assess how a population genomics framework could help delineate the genetic structure of the American lobster (Homarus americanus) throughout much of the species' range and increase the assignment success of individuals to their location of origin. We genotyped 10 156 filtered SNPs using RAD sequencing to delineate genetic structure and perform population assignment for 586 American lobsters collected in 17 locations distributed across a large portion of the species' natural distribution range. Our results revealed the existence of a hierarchical genetic structure, first separating lobsters from the northern and southern part of the range (FCT  = 0.0011; P-value = 0.0002) and then revealing a total of 11 genetically distinguishable populations (mean FST  = 0.00185; CI: 0.0007-0.0021, P-value < 0.0002), providing strong evidence for weak, albeit fine-scale population structuring within each region. A resampling procedure showed that assignment success was highest with a subset of 3000 SNPs having the highest FST . Applying Anderson's (Molecular Ecology Resources, 2010, 10, 701) method to avoid 'high-grading bias', 94.2% and 80.8% of individuals were correctly assigned to their region and location of origin, respectively. Lastly, we showed that assignment success was positively associated with sample size. These results demonstrate that using a large number of SNPs improves fine-scale population structure delineation and population assignment success in a context of weak genetic structure. We discuss the implications of these findings for the conservation and management of highly connected marine species, particularly regarding the geographic scale of demographic independence.

  12. Host islands within the California Northern Channel Islands create fine-scale genetic structure in two sympatric species of the symbiotic ectomycorrhizal fungus Rhizopogon.

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    Grubisha, Lisa C; Bergemann, Sarah E; Bruns, Thomas D

    2007-05-01

    We have examined fine-scale genetic structure of the symbiotic ectomycorrhizal fungi Rhizopogon occidentalis and R. vulgaris on two of the California Channel Islands using five and six microsatellite loci, respectively. Both Rhizopogon species are sympatric on Santa Cruz and Santa Rosa Islands and are ectomycorrhizal with bishop pine (Pinus muricata) on both islands or Santa Rosa Island Torrey pine (P. torreyana ssp. insularis) on Santa Rosa. The combination of disjunct pine host distributions and geographic barriers within and among the islands have created highly structured Rhizopogon populations over very short distances (8.5 km on Santa Cruz Island; F(ST) = 0.258, F(ST) = 0.056, R. occidentalis and R. vulgaris, respectively). Both species show similar patterns of genetic differentiation as a result of limited dispersal between host populations as revealed by a significant isolation by distance relationship (r = 0.69, P analyses, and is most likely a function of the small foraging range of the few mammals that disperse Rhizopogon on these islands and the enormous spore bank characteristic of Rhizopogon species.

  13. Fine-scale genetic structure patterns in two freshwater fish species, Geophagus brasiliensis (Osteichthyes, Cichlidae) and Astyanax altiparanae (Osteichthyes, Characidae) throughout a Neotropical stream.

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    Ferreira, D G; Lima, S C; Frantine-Silva, W; Silva, J F; Apolinário-Silva, C; Sofia, S H; Carvalho, S; Galindo, B A

    2016-10-24

    Streams are very important environments for Neotropical freshwater fish fauna, and possess a high number of species. These small drainages are also highlighted by their intrinsic biological and physicochemical features; however, knowledge on the genetic distribution of fish in these drainages is limited. Therefore, in the present study, RAPD (random amplified polymorphic DNA) and microsatellite markers were used to analyze population differentiation and gene flow of Astyanax altiparanae and Geophagus brasiliensis from three sites (high, medium, and low) throughout the Penacho stream (about 32 km long), which is a Neotropical stream. Both markers revealed higher levels of genetic diversity levels for A. altiparanae (: 90.05; HS: 0.350) compared to G. brasiliensis (: 30.43; HS: 0.118), which may be related to the particular biology of each species. AMOVA revealed significant genetic variation among populations of each species. All pairwise ΦST values were significant, ranging from 0.020 to 0.056 for A. altiparanae samples, and from 0.065 to 0.190 for G. brasiliensis samples. Bayesian clustering analysis corroborated these results and revealed clusters of both A. altiparanae (two based on RAPD data) and G. brasiliensis (two based on RAPD data and three on microsatellite data). Gene flow estimates showed that there were similar rates of migration among A. altiparanae samples and low rates of migration among some G. brasiliensis samples. These results suggest patterns of fine-scale genetic structure for both species in the Penacho stream. This information may enhance knowledge of Neotropical streams and may be useful for future management and conservation activities.

  14. Altitudinal gradients, biogeographic history and microhabitat adaptation affect fine-scale spatial genetic structure in African and Neotropical populations of an ancient tropical tree species.

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    Torroba-Balmori, Paloma; Budde, Katharina B; Heer, Katrin; González-Martínez, Santiago C; Olsson, Sanna; Scotti-Saintagne, Caroline; Casalis, Maxime; Sonké, Bonaventure; Dick, Christopher W; Heuertz, Myriam

    2017-01-01

    The analysis of fine-scale spatial genetic structure (FSGS) within populations can provide insights into eco-evolutionary processes. Restricted dispersal and locally occurring genetic drift are the primary causes for FSGS at equilibrium, as described in the isolation by distance (IBD) model. Beyond IBD expectations, spatial, environmental or historical factors can affect FSGS. We examined FSGS in seven African and Neotropical populations of the late-successional rain forest tree Symphonia globulifera L. f. (Clusiaceae) to discriminate the influence of drift-dispersal vs. landscape/ecological features and historical processes on FSGS. We used spatial principal component analysis and Bayesian clustering to assess spatial genetic heterogeneity at SSRs and examined its association with plastid DNA and habitat features. African populations (from Cameroon and São Tomé) displayed a stronger FSGS than Neotropical populations at both marker types (mean Sp = 0.025 vs. Sp = 0.008 at SSRs) and had a stronger spatial genetic heterogeneity. All three African populations occurred in pronounced altitudinal gradients, possibly restricting animal-mediated seed dispersal. Cyto-nuclear disequilibria in Cameroonian populations also suggested a legacy of biogeographic history to explain these genetic patterns. Conversely, Neotropical populations exhibited a weaker FSGS, which may reflect more efficient wide-ranging seed dispersal by Neotropical bats and other dispersers. The population from French Guiana displayed an association of plastid haplotypes with two morphotypes characterized by differential habitat preferences. Our results highlight the importance of the microenvironment for eco-evolutionary processes within persistent tropical tree populations.

  15. Altitudinal gradients, biogeographic history and microhabitat adaptation affect fine-scale spatial genetic structure in African and Neotropical populations of an ancient tropical tree species

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    Torroba-Balmori, Paloma; Budde, Katharina B.; Heer, Katrin; González-Martínez, Santiago C.; Olsson, Sanna; Scotti-Saintagne, Caroline; Sonké, Bonaventure; Dick, Christopher W.

    2017-01-01

    The analysis of fine-scale spatial genetic structure (FSGS) within populations can provide insights into eco-evolutionary processes. Restricted dispersal and locally occurring genetic drift are the primary causes for FSGS at equilibrium, as described in the isolation by distance (IBD) model. Beyond IBD expectations, spatial, environmental or historical factors can affect FSGS. We examined FSGS in seven African and Neotropical populations of the late-successional rain forest tree Symphonia globulifera L. f. (Clusiaceae) to discriminate the influence of drift-dispersal vs. landscape/ecological features and historical processes on FSGS. We used spatial principal component analysis and Bayesian clustering to assess spatial genetic heterogeneity at SSRs and examined its association with plastid DNA and habitat features. African populations (from Cameroon and São Tomé) displayed a stronger FSGS than Neotropical populations at both marker types (mean Sp = 0.025 vs. Sp = 0.008 at SSRs) and had a stronger spatial genetic heterogeneity. All three African populations occurred in pronounced altitudinal gradients, possibly restricting animal-mediated seed dispersal. Cyto-nuclear disequilibria in Cameroonian populations also suggested a legacy of biogeographic history to explain these genetic patterns. Conversely, Neotropical populations exhibited a weaker FSGS, which may reflect more efficient wide-ranging seed dispersal by Neotropical bats and other dispersers. The population from French Guiana displayed an association of plastid haplotypes with two morphotypes characterized by differential habitat preferences. Our results highlight the importance of the microenvironment for eco-evolutionary processes within persistent tropical tree populations. PMID:28771629

  16. Diet Segregation between Cohabiting Builder and Inquiline Termite Species.

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    Daniela Faria Florencio

    Full Text Available How do termite inquilines manage to cohabit termitaria along with the termite builder species? With this in mind, we analysed one of the several strategies that inquilines could use to circumvent conflicts with their hosts, namely, the use of distinct diets. We inspected overlapping patterns for the diets of several cohabiting Neotropical termite species, as inferred from carbon and nitrogen isotopic signatures for termite individuals. Cohabitant communities from distinct termitaria presented overlapping diet spaces, indicating that they exploited similar diets at the regional scale. When such communities were split into their components, full diet segregation could be observed between builders and inquilines, at regional (environment-wide and local (termitarium scales. Additionally, diet segregation among inquilines themselves was also observed in the vast majority of inspected termitaria. Inquiline species distribution among termitaria was not random. Environmental-wide diet similarity, coupled with local diet segregation and deterministic inquiline distribution, could denounce interactions for feeding resources. However, inquilines and builders not sharing the same termitarium, and thus not subject to potential conflicts, still exhibited distinct diets. Moreover, the areas of the builder's diet space and that of its inquilines did not correlate negatively. Accordingly, the diet areas of builders which hosted inquilines were in average as large as the areas of builders hosting no inquilines. Such results indicate the possibility that dietary partitioning by these cohabiting termites was not majorly driven by current interactive constraints. Rather, it seems to be a result of traits previously fixed in the evolutionary past of cohabitants.

  17. Fine-scale determinants of conservation value of river reaches in a hotspot of native and non-native species diversity.

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    Maceda-Veiga, Alberto; Baselga, Andrés; Sousa, Ronaldo; Vilà, Montserrat; Doadrio, Ignacio; de Sostoa, Adolfo

    2017-01-01

    Global freshwater biodiversity is declining at unprecedented rates while non-native species are expanding. Examining diversity patterns across variable river conditions can help develop better management strategies. However, many indicators can be used to determine the conservartion value of aquatic communities, and little is known of how well they correlate to each other in making diagnostics, including when testing for the efficacy of protected areas. Using an extensive data set (99,700km(2), n=530 sites) across protected and unprotected river reaches in 15 catchments of NE Spain, we examine correlations among 20 indicators of conservation value of fish communities, including the benefits they provide to birds and threatened mammals and mussels. Our results showed that total native fish abundance or richness correlated reasonably well with many native indicators. However, the lack of a strong congruence led modelling techniques to identify different river attributes for each indicator of conservation value. Overall, tributaries were identified as native fish refugees, and nutrient pollution, salinization, low water velocity and poor habitat structure as major threats to the native biota. We also found that protected areas offered limited coverage to major components of biodiversity, including rarity, threat and host-parasite relationships, even though values of non-native indicators were notably reduced. In conclusion, restoring natural hydrological regimes and water chemical status is a priority to stem freshwater biodiversity loss in this region. A complementary action can be the protection of tributaries, but more studies examining multiple components of diversity are necessary to fully test their potential as fluvial reserves in Mediterranean climate areas. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Segregation of male-sterility alleles across a species boundary.

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    Weller, S G; Sakai, A K; Culley, T M; Duong, L; Danielson, R E

    2014-02-01

    Hybrid zones may serve as bridges permitting gene flow between species, including alleles influencing the evolution of breeding systems. Using greenhouse crosses, we assessed the likelihood that a hybrid zone could serve as a conduit for transfer of nuclear male-sterility alleles between a gynodioecious species and a hermaphroditic species with very rare females in some populations. Segregation patterns in progeny of crosses between rare females of hermaphroditic Schiedea menziesii and hermaphroditic plants of gynodioecious Schiedea salicaria heterozygous at the male-sterility locus, and between female S. salicaria and hermaphroditic plants from the hybrid zone, were used to determine whether male-sterility was controlled at the same locus in the parental species and the hybrid zone. Segregations of females and hermaphrodites in approximately equal ratios from many of the crosses indicate that the same nuclear male-sterility allele occurs in the parent species and the hybrid zone. These rare male-sterility alleles in S. menziesii may result from gene flow from S. salicaria through the hybrid zone, presumably facilitated by wind pollination in S. salicaria. Alternatively, rare male-sterility alleles might result from a reversal from gynodioecy to hermaphroditism in S. menziesii, or possibly de novo evolution of male sterility. Phylogenetic analysis indicates that some species of Schiedea have probably evolved separate sexes independently, but not in the lineage containing S. salicaria and S. menziesii. High levels of selfing and expression of strong inbreeding depression in S. menziesii, which together should favour females in populations, argue against a reversal from gynodioecy to hermaphroditism in S. menziesii.

  19. No evidence for niche segregation in a North American Cattail (Typha) species complex.

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    McKenzie-Gopsill, Andrew; Kirk, Heather; Drunen, Wendy Van; Freeland, Joanna R; Dorken, Marcel E

    2012-05-01

    Interspecific hybridization can lead to a breakdown of species boundaries, and is of particular concern in cases in which one of the parental species is invasive. Cattails (Typha spp.) have increased their abundance in the Great Lakes region of North America over the past 150 years. This increase in the distribution of cattails is associated with hybridization between broad-leaved (Typha latifolia) and narrow-leaved cattails (T. angustifolia). The resulting hybrids occur predominantly as F(1)s, which are known as T. × glauca, although later-generation hybrids have also been documented. It has been proposed that in sympatric populations, the parental species and hybrids are often spatially segregated according to growth in contrasting water depths, and that this should promote the maintenance of parental species. In this study, we tested the hypothesis that the two species and their hybrids segregate along a water-depth gradient at sites where they are sympatric. We identified the two parental species and their hybrids using molecular genetic markers (SSR), and measured shoot elevations (a proxy for water depth) at 18 sites in Southern Ontario, Canada. We found no evidence for niche segregation among species based on elevation. Our data indicate that all three lineages compete for similar habitat where they co-occur suggesting that there is potential for an overall loss of biodiversity in the species complex, particularly if the hybrid lineage is more vigorous compared to the parental species, as has been suggested by other authors.

  20. Modelling Fine Scale Movement Corridors for the Tricarinate Hill Turtle

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    Mondal, I.; Kumar, R. S.; Habib, B.; Talukdar, G.

    2016-06-01

    Habitat loss and the destruction of habitat connectivity can lead to species extinction by isolation of population. Identifying important habitat corridors to enhance habitat connectivity is imperative for species conservation by preserving dispersal pattern to maintain genetic diversity. Circuit theory is a novel tool to model habitat connectivity as it considers habitat as an electronic circuit board and species movement as a certain amount of current moving around through different resistors in the circuit. Most studies involving circuit theory have been carried out at small scales on large ranging animals like wolves or pumas, and more recently on tigers. This calls for a study that tests circuit theory at a large scale to model micro-scale habitat connectivity. The present study on a small South-Asian geoemydid, the Tricarinate Hill-turtle (Melanochelys tricarinata), focuses on habitat connectivity at a very fine scale. The Tricarinate has a small body size (carapace length: 127-175 mm) and home range (8000-15000 m2), with very specific habitat requirements and movement patterns. We used very high resolution Worldview satellite data and extensive field observations to derive a model of landscape permeability at 1 : 2,000 scale to suit the target species. Circuit theory was applied to model potential corridors between core habitat patches for the Tricarinate Hill-turtle. The modelled corridors were validated by extensive ground tracking data collected using thread spool technique and found to be functional. Therefore, circuit theory is a promising tool for accurately identifying corridors, to aid in habitat studies of small species.

  1. On the segregation of chemical species in a clear boundary layer over heterogeneous land surfaces

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    H. G. Ouwersloot

    2011-07-01

    Full Text Available We have systematically studied the inability of boundary layer turbulence to efficiently mix reactive species. This creates regions where the species are accumulated in a correlated or anti-correlated way, thereby modifying the mean reactivity. Here, we quantify this modification by the intensity of segregation, IS, and analyse the driving mechanisms: heterogeneity of the surface moisture and heat fluxes, various background wind patterns and non-uniform isoprene emissions. For typical conditions in the Amazon rain forest, applying homogeneous surface forcings, the isoprene-OH reaction rate is altered by less than 10 %. This is substantially smaller than the previously assumed IS of 50 % in recent large-scale model analyses of tropical rain forest chemistry. Spatial heterogeneous surface emissions enhance the segregation of species, leading to alterations of the chemical reaction rates of up to 20 %. For these cases, spatial segregation is induced by heterogeneities of the surface properties: a cool and wet forested patch characterized by high isoprene emissions is alternated with a warm and dry patch that represents pasture with relatively low isoprene emissions. The intensities of segregation are enhanced when the background wind direction is parallel to the borders between the patches and reduced in case of a perpendicular wind direction. The effects of segregation on trace gas concentrations vary per species. For the highly reactive OH, the differences in concentration averaged over the boundary layer are less than 2 % compared to homogeneous surface conditions, while the isoprene concentration is increased by as much as 12 % due to the reduced chemical reaction rates. These processes take place at the sub-grid scale of chemistry transport models and therefore need to be parameterized.

  2. Fish passage in plains and prairie waterways and predicting fish response to climate change: Fine scale fish passage and physiological response data needed to restore and conserve plains and prairie pothole fish species

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The research aims to build on two existing projects underway: (1) to improve fish passage and landscape connectivity for native species; and (2) determine thermal...

  3. Temporal segregation in coexisting Acomys species: the role of odour.

    Science.gov (United States)

    Haim, A; Rozenfeld, F M

    1993-12-01

    To understand the mechanisms underlying displacement (the shift from nocturnal to diurnal activity), in one of the two coexisting spiny mice (genus Acomys), the effect of chemical cues released by A. cahirinus on the time of activity of A. russatus was tested Six golden spiny mice (A. russatus), which prior to the experiments were kept separate from common spiny mice (A. cahirinus), showed nocturnal activity. They were exposed to chemical cues from the urine and faeces of conspecific and heterospecific mice of the opposite sex. The onset of activity in these mice was recorded. While the urine and faeces of conspecific mice did not have a significant effect on the time of onset of activity, heterospecific urine and faeces did cause a significant (p < 0.001) time shift and, a day after they were introduced, activity started 6.8 +/- 1.9 h earlier. This shift also took place on the second day. The results of this study suggest that the mechanism for displacement of A. russatus from nocturnal activity is by chemical signals released by A. cahirinus. Therefore, it may be concluded that chemical cues maintain time separation between these two species.

  4. Coexisting orchid species have distinct mycorrhizal communities and display strong spatial segregation.

    Science.gov (United States)

    Jacquemyn, Hans; Brys, Rein; Merckx, Vincent S F T; Waud, Michael; Lievens, Bart; Wiegand, Thorsten

    2014-04-01

    Because orchids are dependent on mycorrhizal fungi for germination and establishment of seedlings, differences in the mycorrhizal communities associating with orchids can be expected to mediate the abundance, spatial distribution and coexistence of terrestrial orchids in natural communities. We assessed the small-scale spatial distribution of seven orchid species co-occurring in 25 × 25 m plots in two Mediterranean grasslands. In order to characterize the mycorrhizal community associating with each orchid species, 454 pyrosequencing was used. The extent of spatial clustering was assessed using techniques of spatial point pattern analysis. The community of mycorrhizal fungi consisted mainly of members of the Tulasnellaceae, Thelephoraceae and Ceratobasidiaceae, although sporadically members of the Sebacinaceae, Russulaceae and Cortinariaceae were observed. Pronounced differences in mycorrhizal communities were observed between species, whereas strong clustering and significant segregation characterized the spatial distribution of orchid species. However, spatial segregation was not significantly related to phylogenetic dissimilarity of fungal communities. Our results indicate that co-occurring orchid species have distinctive mycorrhizal communities and show strong spatial segregation, suggesting that mycorrhizal fungi are important factors driving niche partitioning in terrestrial orchids and may therefore contribute to orchid coexistence.

  5. Landscape and fine scale habitat associations of the Loggerhead Shrike

    Science.gov (United States)

    Michaels, H.L.; Cully, J.E.

    1998-01-01

    This study was conducted to determine landscape and fine-scale vegetative variables associated with breeding Loggerhead Shrikes (Lanius ludovicianus) on Fort Riley Military Reservation, Kansas. Because Fort Riley is an Army training site, the influences of training disturbance to the vegetation, and range management practices on bird habitat patterns were also investigated. Breeding birds were surveyed in 1995 and 1996 using point counts. Survey plots were identified, a priori, at the landscape scale as either grassland, savannah, or woodland edge according to cover by woody vegetation. In 1996, fine-scale habitat at survey points and at bird use sites was measured and a principal components analysis used to characterize the fine-scale herbaceous vegetation structure. A military disturbance index was developed to quantify the severity of vehicle disturbance to the vegetation at survey and bird use sites. Shrikes were associated with savannah habitat at the landscape scale. Sites used by Loggerhead Shrikes were characterized at the fine-scale by tall, sparse, structurally heterogeneous herbaceous vegetation with high standing dead plant cover and low litter cover. At the fine-scale, tree and shrub density did not differ between sites used and not used by shrikes. Used sites did not differ from survey sites with respect to military training disturbance, hay harvest, or the number of years since a site was last burned. Our results in this study suggest that the shifting mosaic of vegetation on Fort Riley resulting from training and range management practices maintains adequate habitat for breeding shrikes.

  6. Segregation process and phase transition in cyclic predator-prey models with even number of species

    CERN Document Server

    Szabo, Gyorgy; Sznaider, Gustavo Ariel

    2007-01-01

    We study a spatial cyclic predator-prey model with an even number of species (for n=4, 6, and 8) that allows the formation of two defective alliances consisting of the even and odd label species. The species are distributed on the sites of a square lattice. The evolution of spatial distribution is governed by iteration of two elementary processes on neighboring sites chosen randomly: if the sites are occupied by a predator-prey pair then the predator invades the prey's site; otherwise the species exchange their site with a probability $X$. For low $X$ values a self-organizing pattern is maintained by cyclic invasions. If $X$ exceeds a threshold value then two types of domains grow up that formed by the odd and even label species, respectively. Monte Carlo simulations indicate the blocking of this segregation process within a range of X for n=8.

  7. Breed locally, disperse globally: fine-scale genetic structure despite landscape-scale panmixia in a fire-specialist.

    Directory of Open Access Journals (Sweden)

    Jennifer C Pierson

    Full Text Available An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go 'extinct' during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic structuring or how this changes over time in ephemeral patches. We predicted that species that specialize on ephemeral habitats will delay dispersal to exploit natal habitat patches while resources are plentiful and thus display fine-scale structure. To investigate this idea, we evaluated the effect of frequent colonization of ephemeral habitats on the fine-scale genetic structure of a fire specialist, the black-backed woodpecker (Picoides arcticus and found a pattern of fine-scale genetic structure. We then tested for differences in spatial structure between sexes and detected a pattern consistent with male-biased dispersal. We also detected a temporal increase in relatedness among individuals within newly burned forest patches. Our results indicate that specialist species that outlive their ephemeral patches can accrue significant fine-scale spatial structure that does not necessarily affect spatial structure at larger scales. This highlights the importance of both spatial and temporal scale considerations in both sampling and data interpretation of molecular genetic results.

  8. Breed locally, disperse globally: fine-scale genetic structure despite landscape-scale panmixia in a fire-specialist.

    Science.gov (United States)

    Pierson, Jennifer C; Allendorf, Fred W; Drapeau, Pierre; Schwartz, Michael K

    2013-01-01

    An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go 'extinct' during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic structuring or how this changes over time in ephemeral patches. We predicted that species that specialize on ephemeral habitats will delay dispersal to exploit natal habitat patches while resources are plentiful and thus display fine-scale structure. To investigate this idea, we evaluated the effect of frequent colonization of ephemeral habitats on the fine-scale genetic structure of a fire specialist, the black-backed woodpecker (Picoides arcticus) and found a pattern of fine-scale genetic structure. We then tested for differences in spatial structure between sexes and detected a pattern consistent with male-biased dispersal. We also detected a temporal increase in relatedness among individuals within newly burned forest patches. Our results indicate that specialist species that outlive their ephemeral patches can accrue significant fine-scale spatial structure that does not necessarily affect spatial structure at larger scales. This highlights the importance of both spatial and temporal scale considerations in both sampling and data interpretation of molecular genetic results.

  9. Fine-Scale Habitat Heterogeneity Influences Occupancy in Terrestrial Mammals in a Temperate Region of Australia.

    Science.gov (United States)

    Stirnemann, Ingrid; Mortelliti, Alessio; Gibbons, Philip; Lindenmayer, David B

    2015-01-01

    Vegetation heterogeneity is an inherent feature of most ecosystems, characterises the structure of habitat, and is considered an important driver of species distribution patterns. However, quantifying fine-scale heterogeneity of vegetation cover can be time consuming, and therefore it is seldom measured. Here, we determine if heterogeneity is worthwhile measuring, in addition to the amount of cover, when examining species distribution patterns. Further, we investigated the effect of the surrounding landscape heterogeneity on species occupancy. We tested the effect of cover and heterogeneity of trees and shrubs, and the context of the surrounding landscape (number of habitats and distance to an ecotone) on site occupancy of three mammal species (the black wallaby [Wallabia bicolor], the long-nosed bandicoot [Perameles nasuta], and the bush rat [Rattus fuscipes]) within a naturally heterogeneous landscape in a temperate region of Australia. We found that fine-scale heterogeneity of vegetation attributes is an important driver of mammal occurrence of two of these species. Further, we found that, although all three species responded positively to vegetation heterogeneity, different mammals vary in their response to different types of vegetation heterogeneity measurement. For example, the black wallaby responded to the proximity of an ecotone, and the bush rat and the long-nosed bandicoot responded to fine-scale heterogeneity of small tree cover, whereas none of the mammals responded to broad scale heterogeneity (i.e., the number of habitat types). Our results highlight the influence of methodological decisions, such as how heterogeneity vegetation is measured, in quantifying species responses to habitat structures. The findings confirm the importance of choosing meaningful heterogeneity measures when modelling the factors influencing occupancy of the species of interest.

  10. Mutualistic mimicry enhances species diversification through spatial segregation and extension of the ecological niche space.

    Science.gov (United States)

    Aubier, Thomas G; Elias, Marianne; Llaurens, Violaine; Chazot, Nicolas

    2017-04-01

    Species richness varies among clades, yet the drivers of diversification creating this variation remain poorly understood. While abiotic factors likely drive some of the variation in species richness, ecological interactions may also contribute. Here, we examine one class of potential contributors to species richness variation that is particularly poorly understood: mutualistic interactions. We aim to elucidate large-scale patterns of diversification mediated by mutualistic interactions using a spatially explicit population-based model. We focus on mutualistic Müllerian mimicry between conspicuous toxic prey species, where convergence in color patterns emerges from predators' learning process. To investigate the effects of Müllerian mimicry on species diversification, we assume that some speciation events stem from shifts in ecological niches, and can also be associated with shift in mimetic color pattern. Through the emergence of spatial mosaics of mimetic color patterns, Müllerian mimicry constrains the geographical distribution of species and allows different species occupying similar ecological niches to exist simultaneously in different regions. Müllerian mimicry and the resulting spatial segregation of mimetic color patterns thus generate more balanced phylogenetic trees and increase overall species diversity. Our study sheds light on complex effects of Müllerian mimicry on ecological, spatial, and phylogenetic diversification. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  11. Genetic Segregation and Genomic Hybridization Patterns Support an Allotetraploid Structure and Disomic Inheritance for Salix Species

    Directory of Open Access Journals (Sweden)

    Gianni Barcaccia

    2014-09-01

    Full Text Available The Salix alba L. (white willow—Salix fragilis L. (crack willow complex includes closely related polyploid species, mainly tetraploid (2n = 4x = 76, which are dioecious and hence obligate allogamous. Because little is known about the genome constitution and chromosome behavior of these pure willow trees, genetic analysis of their naturally occurring interspecific polyploid hybrids is still very difficult. A two-way pseudo-testcross strategy was exploited using single-dose AFLP markers in order to assess the main inheritance patterns of tetraploid biotypes (disomy vs. tetrasomy in segregating populations stemmed from S. alba × S. fragilis crosses and reciprocals. In addition, a genomic in situ hybridization (GISH technology was implemented in willow to shed some light on the genome structure of S. alba and S. fragilis species, and their hybrids (allopolyploidy vs. autopolyploidy. The frequency of S. alba-specific molecular markers was almost double compared to that of S. fragilis-specific ones, suggesting the phylogenetic hypothesis of S. fragilis as derivative species from S. alba-like progenitors. Cytogenetic observations at pro-metaphase revealed about half of the chromosome complements being less contracted than the remaining ones, supporting an allopolyploid origin of both S. alba and S. fragilis. Both genetic segregation and genomic hybridization data are consistent with an allotetraploid nature of the Salix species. In particular, the vast majority of the AFLP markers were inherited according to disomic patterns in S. alba × S. fragilis populations and reciprocals. Moreover, in all S. alba against S. fragilis hybridizations and reciprocals, GISH signals were observed only on the contracted chromosomes whereas the non-contracted chromosomes were never hybridized. In conclusion, half of the chromosomes of the pure species S. alba and S. fragilis are closely related and they could share a common diploid ancestor, while the rest of

  12. Species associations in a species-rich subtropical forest were not well-explained by stochastic geometry of biodiversity.

    Directory of Open Access Journals (Sweden)

    Qinggang Wang

    Full Text Available The stochastic dilution hypothesis has been proposed to explain species coexistence in species-rich communities. The relative importance of the stochastic dilution effects with respect to other effects such as competition and habitat filtering required to be tested. In this study, using data from a 25-ha species-rich subtropical forest plot with a strong topographic structure at Badagongshan in central China, we analyzed overall species associations and fine-scale species interactions between 2,550 species pairs. The result showed that: (1 the proportion of segregation in overall species association analysis at 2 m neighborhood in this plot followed the prediction of the stochastic dilution hypothesis that segregations should decrease with species richness but that at 10 m neighborhood was higher than the prediction. (2 The proportion of no association type was lower than the expectation of stochastic dilution hypothesis. (3 Fine-scale species interaction analyses using Heterogeneous Poisson processes as null models revealed a high proportion (47% of significant species effects. However, the assumption of separation of scale of this method was not fully met in this plot with a strong fine-scale topographic structure. We also found that for species within the same families, fine-scale positive species interactions occurred more frequently and negative ones occurred less frequently than expected by chance. These results suggested effects of environmental filtering other than species interaction in this forest. (4 We also found that arbor species showed a much higher proportion of significant fine-scale species interactions (66% than shrub species (18%. We concluded that the stochastic dilution hypothesis only be partly supported and environmental filtering left discernible spatial signals in the spatial associations between species in this species-rich subtropical forest with a strong topographic structure.

  13. Species associations in a species-rich subtropical forest were not well-explained by stochastic geometry of biodiversity.

    Science.gov (United States)

    Wang, Qinggang; Bao, Dachuan; Guo, Yili; Lu, Junmeng; Lu, Zhijun; Xu, Yaozhan; Zhang, Kuihan; Liu, Haibo; Meng, Hongjie; Jiang, Mingxi; Qiao, Xiujuan; Huang, Handong

    2014-01-01

    The stochastic dilution hypothesis has been proposed to explain species coexistence in species-rich communities. The relative importance of the stochastic dilution effects with respect to other effects such as competition and habitat filtering required to be tested. In this study, using data from a 25-ha species-rich subtropical forest plot with a strong topographic structure at Badagongshan in central China, we analyzed overall species associations and fine-scale species interactions between 2,550 species pairs. The result showed that: (1) the proportion of segregation in overall species association analysis at 2 m neighborhood in this plot followed the prediction of the stochastic dilution hypothesis that segregations should decrease with species richness but that at 10 m neighborhood was higher than the prediction. (2) The proportion of no association type was lower than the expectation of stochastic dilution hypothesis. (3) Fine-scale species interaction analyses using Heterogeneous Poisson processes as null models revealed a high proportion (47%) of significant species effects. However, the assumption of separation of scale of this method was not fully met in this plot with a strong fine-scale topographic structure. We also found that for species within the same families, fine-scale positive species interactions occurred more frequently and negative ones occurred less frequently than expected by chance. These results suggested effects of environmental filtering other than species interaction in this forest. (4) We also found that arbor species showed a much higher proportion of significant fine-scale species interactions (66%) than shrub species (18%). We concluded that the stochastic dilution hypothesis only be partly supported and environmental filtering left discernible spatial signals in the spatial associations between species in this species-rich subtropical forest with a strong topographic structure.

  14. A fine-scale chimpanzee genetic map from population sequencing

    Science.gov (United States)

    Auton, Adam; Fledel-Alon, Adi; Pfeifer, Susanne; Venn, Oliver; Ségurel, Laure; Street, Teresa; Leffler, Ellen M.; Bowden, Rory; Aneas, Ivy; Broxholme, John; Humburg, Peter; Iqbal, Zamin; Lunter, Gerton; Maller, Julian; Hernandez, Ryan D.; Melton, Cord; Venkat, Aarti; Nobrega, Marcelo A.; Bontrop, Ronald; Myers, Simon; Donnelly, Peter; Przeworski, Molly; McVean, Gil

    2012-01-01

    To study the evolution of recombination rates in apes, we developed methodology to construct a fine-scale genetic map from high throughput sequence data from ten Western chimpanzees, Pan troglodytes verus. Compared to the human genetic map, broad-scale recombination rates tend to be conserved, but with exceptions, particularly in regions of chromosomal rearrangements and around the site of ancestral fusion in human chromosome 2. At fine-scales, chimpanzee recombination is dominated by hotspots, which show no overlap with humans even though rates are similarly elevated around CpG islands and decreased within genes. The hotspot-specifying protein PRDM9 shows extensive variation among Western chimpanzees and there is little evidence that any sequence motifs are enriched in hotspots. The contrasting locations of hotspots provide a natural experiment, which demonstrates the impact of recombination on base composition. PMID:22422862

  15. The effects of fine-scale disturbances on demography and population dynamics of the clonal moss Hylocomium splendens

    NARCIS (Netherlands)

    Rydgren, K.; Kroon, de H.; Okland, R.H.; Groenendael, van J.

    2001-01-01

    1. The boreal forest is subject to disturbance but the effects on population dynamics are poorly understood. We investigated how a prominent species of the forest floor, the clonal moss Hylocomium splendens, responded to different types of fine-scale disturbance. 2. Canopy gap formation was simulate

  16. Resource partitioning amongst five coexisting species of gurnards (Scorpaeniforme: Triglidae): Role of trophic and habitat segregation

    Science.gov (United States)

    Lopez-Lopez, L.; Preciado, I.; Velasco, F.; Olaso, I.; Gutiérrez-Zabala, J. L.

    2011-08-01

    Feeding habits and habitat preferences of five related species ( Aspitrigla cuculus, Chelidonichthys lucerna, Chelidonichthys obscurus, Eutrigla gurnardus and Trigla lyra) (Scorpaeniformes: Triglidae) were studied in the southern Bay of Biscay. Specimens were collected during annual bottom trawl surveys carried out every autumn between 1990 and 2008 on soft bottoms of the Galician and Cantabrian Sea continental shelf between 30 and 800 m depth. All species were found to display a different depth distribution, despite co-occurring in many of the hauls (co-occurrence percentage ranged between 4.45 and 34.77%). Although depth was the main variable explaining the triglid distribution, latitude, temperature and sediment type were also important driving factors. Regarding feeding habits all triglids fed mainly on crustaceans, their main prey being Alpheus glaber, Polybius henslowii, Scyllarus arctus, Chlorotocus crassicornis and Pagurus prideaux. However, fish accounted for a considerable proportion of the diet with Gadiculus argenteus, Callionymus spp., and Cepola rubescens being the most common fish prey. Ontogenetic changes in diet were evident in all species but C. obscurus. Dietary overlap, determined by the Schoener Index greatly differed amongst species pairs ranging between 0.10 and 0.63. Considering all ontogenetic groups in the triglid assemblage, either diet or habitat segregation occurred between most of them. This fact suggests that any of these strategies on their own would suffice in order to avoid inter and intra specific competitions. Nevertheless, habitat partitioning occurred mainly at the inter-specific level and trophic segregation at the intra-specific level. A. cuculus and E. gurnardus showed the poorest resource partitioning in the assemblage, possibly as a consequence of the increasing abundance of the population of the first during the last decades.

  17. Seasonal sexual segregation in two Thalassarche albatross species: competitive exclusion, reproductive role specialization or foraging niche divergence?

    Science.gov (United States)

    Phillips, R A; Silk, J R D; Phalan, B; Catry, P; Croxall, J P

    2004-06-22

    Sexual segregation by micro- or macrohabitat is common in birds, and usually attributed to size-mediated dominance and exclusion of females by larger males, trophic niche divergence or reproductive role specialization. Our study of black-browed albatrosses, Thalassarche melanophrys, and grey-headed albatrosses, T. chrysostoma, revealed an exceptional degree of sexual segregation during incubation, with largely mutually exclusive core foraging ranges for each sex in both species. Spatial segregation was not apparent during brood-guard or post-guard chick rearing, when adults are constrained to feed close to colonies, providing no evidence for dominance-related competitive exclusion at the macrohabitat level. A comprehensive morphometric comparison indicated considerable species and sexual dimorphism in wing area and wing loading that corresponded, both within and between species, to broad-scale habitat preferences relating to wind strength. We suggest that seasonal sexual segregation in these two species is attributable to niche divergence mediated by differences in flight performance. Such sexual segregation may also have implications for conservation in relation to sex-specific overlap with commercial fisheries.

  18. Fine-Scale Crossover Rate Variation on the Caenorhabditis elegans X Chromosome

    Science.gov (United States)

    Bernstein, Max R.; Rockman, Matthew V.

    2016-01-01

    Meiotic recombination creates genotypic diversity within species. Recombination rates vary substantially across taxa, and the distribution of crossovers can differ significantly among populations and between sexes. Crossover locations within species have been found to vary by chromosome and by position within chromosomes, where most crossover events occur in small regions known as recombination hotspots. However, several species appear to lack hotspots despite significant crossover heterogeneity. The nematode Caenorhabditis elegans was previously found to have the least fine-scale variation in crossover distribution among organisms studied to date. It is unclear whether this pattern extends to the X chromosome given its unique compaction through the pachytene stage of meiotic prophase in hermaphrodites. We generated 798 recombinant nested near-isogenic lines (NILs) with crossovers in a 1.41 Mb region on the left arm of the X chromosome to determine if its recombination landscape is similar to that of the autosomes. We find that the fine-scale variation in crossover rate is lower than that of other model species, and is inconsistent with hotspots. The relationship of genomic features to crossover rate is dependent on scale, with GC content, histone modifications, and nucleosome occupancy being negatively associated with crossovers. We also find that the abundances of 4- to 6-bp DNA motifs significantly explain crossover density. These results are consistent with recombination occurring at unevenly distributed sites of open chromatin. PMID:27172189

  19. A quantitative analysis of fine scale distribution of intertidal meiofauna in response to food resources

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Gauns, M.

    Fine scale vertical and spatial distribution of meiofauna in relation to food abundance was studied in the intertidal sediment at Dias Beach. The major abiotic factors showed significant changes and progressive fine scale decrease in vertical...

  20. Fine scale habitat use by age-1 stocked muskellunge and wild northern pike in an upper St. Lawrence River bay

    Science.gov (United States)

    Farrell, John M.; Kapuscinski, Kevin L.; Underwood, Harold

    2014-01-01

    Radio telemetry of stocked muskellunge (n = 6) and wild northern pike (n = 6) was used to track late summer and fall movements from a common release point in a known shared nursery bay to test the hypothesis that age-1 northern pike and stocked muskellunge segregate and have different habitat affinities. Water depth, temperature, substrate and aquatic vegetation variables were estimated for each muskellunge (n = 103) and northern pike (n = 131) position and nested ANOVA comparisons by species indicated differences in habitat use. Muskellunge exhibited a greater displacement from the release point and used habitat in shallower water depths (mean = 0.85 m, SE = 0.10) than northern pike (mean = 1.45 m, SE = 0.08). Both principal components analysis (PCA) and principal components ordination (PCO) were used to interpret underlying gradients relative to fish positions in two-dimensional space. Our analysis indicated that a separation of age-1 northern pike and muskellunge occurred 7 d post-release. This first principal component explained 48% of the variation in habitat use. Northern pike locations were associated with deeper habitats that generally had softer silt substrates and dense submersed vegetation. Muskellunge locations post-acclimation showed greater association with shallower habitats containing firmer sandy and clay substrates and emergent vegetation. The observed differences in habitat use suggest that fine-scale ecological separation occurred between these stocked muskellunge and wild northern pike, but small sample sizes and potential for individual variation limit extension of these conclusions. Further research is needed to determine if these patterns exist between larger samples of fishes over a greater range of habitats.

  1. Fine-Scale Filamentary Structure in Coronal Streamers

    Science.gov (United States)

    Woo, Richard; Armstrong, John W.; Bird, Michael K.; Paetzold, Martin

    1995-01-01

    Doppler scintillation measurements of a coronal streamer lasting several solar rotations have been conducted by Ulysses in 1991 over a heliocentric distance range of 14-77 R(sub 0). By showing that the solar corona is filamentary, and that Doppler frequency is the radio counterpart of white-light eclipse pictures processed to enhance spatial gradients, it is demonstrated that Doppler scintillation measurements provide the high spatial resolution that has long eluded white-light coronagraph measurements. The region of enhanced scintillation, spanning an angular extent of 1.8 deg in heliographic longitude, coincides with the radially expanding streamer stalk and represents filamentary structure with scale sizes at least as small as 340 km (0.5 sec) when extrapolated to the Sun. Within the stalk of the streamer, the fine-scale structure corresponding to scale sizes in the range of 20-340 km at the Sun and associated with closed magnetic fields amounts to a few percent of the mean density, while outside the stalk, the fine-scale structure associated with open fields is an order of magnitude lower. Clustering of filamentary structure that takes place within the stalk of the streamer is suggestive of multiple current sheets. Comparison with ISEE 3 in situ plasma measurements shows that significant evolution resulting from dynamic interaction with increasing heliocentric distance takes place by the time streamers reach Earth orbit.

  2. Reproductive constraints influence habitat accessibility, segregation, and preference of sympatric albatross species.

    Science.gov (United States)

    Kappes, Michelle A; Shaffer, Scott A; Tremblay, Yann; Foley, David G; Palacios, Daniel M; Bograd, Steven J; Costa, Daniel P

    2015-01-01

    The spatiotemporal distribution of animals is dependent on a suite of factors, including the distribution of resources, interactions within and between species, physiological limitations, and requirements for reproduction, dispersal, or migration. During breeding, reproductive constraints play a major role in the distribution and behavior of central place foragers, such as pelagic seabirds. We examined the foraging behavior and marine habitat selection of Laysan (Phoebastria immutabilis) and black-footed (P. nigripes) albatrosses throughout their eight month breeding cycle at Tern Island, Northwest Hawaiian Islands to evaluate how variable constraints of breeding influenced habitat availability and foraging decisions. We used satellite tracking and light-based geolocation to determine foraging locations of individuals, and applied a biologically realistic null usage model to generate control locations and model habitat preference under a case-control design. Remotely sensed oceanographic data were used to characterize albatross habitats in the North Pacific. Individuals of both species ranged significantly farther and for longer durations during incubation and chick-rearing compared to the brooding period. Interspecific segregation of core foraging areas was observed during incubation and chick-rearing, but not during brooding. At-sea activity patterns were most similar between species during brooding; neither species altered foraging effort to compensate for presumed low prey availability and high energy demands during this stage. Habitat selection during long-ranging movements was most strongly associated with sea surface temperature for both species, with a preference for cooler ocean temperatures compared to overall availability. During brooding, lower explanatory power of habitat models was likely related to the narrow range of ocean temperatures available for selection. Laysan and black-footed albatrosses differ from other albatross species in that they breed

  3. The role of fine-scale anatomical structure in the dynamics of reentry in computational models of the rabbit ventricles.

    Science.gov (United States)

    Bishop, Martin J; Plank, Gernot

    2012-09-15

    Fine-scale anatomical structures in the heart may play an important role in sustaining cardiac arrhythmias. However, the extent of this role and how it may differ between species are not fully understood. In this study we used computational modelling to assess the impact of anatomy upon arrhythmia maintenance in the rabbit ventricles. Specifically, we quantified the dynamics of excitation wavefronts during episodes of simulated tachyarrhythmias and fibrillatory arrhythmias, defined as being respectively characterised by relatively low and high spatio-temporal disorganisation.Two computational models were used: a highly anatomically detailed MR-derived rabbit ventricular model (representing vasculature, endocardial structures) and a simplified equivalent model, constructed from the same MR-data but lacking such fine-scale anatomical features. During tachyarrhythmias, anatomically complex and simplified models showed very similar dynamics; however, during fibrillatory arrhythmias, as activation wavelength decreased, the presence of fine-scale anatomical details appeared to marginally increase disorganisation of wavefronts during arrhythmias in the complex model. Although a small amount of clustering of reentrant rotor centres (filaments) around endocardial structures was witnessed in follow-up analysis (which slightly increased during fibrillation as rotor size decreased), this was significantly less than previously reported in large animals. Importantly, no anchoring of reentrant rotors was visibly identifiable in arrhythmia movies. These differences between tachy- and fibrillatory arrhythmias suggest that the relative size of reentrant rotors with respect to anatomical obstacles governs the influence of fine-scale anatomy in the maintenance of ventricular arrhythmias in the rabbit. In conclusion, our simulations suggest that fine-scale anatomical features play little apparent role in the maintenance of tachyarrhythmias in the rabbit ventricles and, contrary to

  4. A heterogeneity test for fine-scale genetic structure.

    Science.gov (United States)

    Smouse, Peter E; Peakall, Rod; Gonzales, Eva

    2008-07-01

    For organisms with limited vagility and/or occupying patchy habitats, we often encounter nonrandom patterns of genetic affinity over relatively small spatial scales, labelled fine-scale genetic structure. Both the extent and decay rate of that pattern can be expected to depend on numerous interesting demographic, ecological, historical, and mating system factors, and it would be useful to be able to compare different situations. There is, however, no heterogeneity test currently available for fine-scale genetic structure that would provide us with any guidance on whether the differences we encounter are statistically credible. Here, we develop a general nonparametric heterogeneity test, elaborating on standard autocorrelation methods for pairs of individuals. We first develop a 'pooled within-population' correlogram, where the distance classes (lags) can be defined as functions of distance. Using that pooled correlogram as our null-hypothesis reference frame, we then develop a heterogeneity test of the autocorrelations among different populations, lag-by-lag. From these single-lag tests, we construct an analogous test of heterogeneity for multilag correlograms. We illustrate with a pair of biological examples, one involving the Australian bush rat, the other involving toadshade trillium. The Australian bush rat has limited vagility, and sometimes occupies patchy habitat. We show that the autocorrelation pattern diverges somewhat between continuous and patchy habitat types. For toadshade trillium, clonal replication in Piedmont populations substantially increases autocorrelation for short lags, but clonal replication is less pronounced in mountain populations. Removal of clonal replicates reduces the autocorrelation for short lags and reverses the sign of the difference between mountain and Piedmont correlograms.

  5. Fine-Scale Genetic Structure and Cryptic Associations Reveal Evidence of Kin-Based Sociality in the African Forest Elephant

    OpenAIRE

    Stephanie G Schuttler; Jessica A Philbrick; Jeffery, Kathryn J.; Eggert, Lori S.

    2014-01-01

    Spatial patterns of relatedness within animal populations are important in the evolution of mating and social systems, and have the potential to reveal information on species that are difficult to observe in the wild. This study examines the fine-scale genetic structure and connectivity of groups within African forest elephants, Loxodonta cyclotis, which are often difficult to observe due to forest habitat. We tested the hypothesis that genetic similarity will decline with increasing geograph...

  6. Hierarchical spatial segregation of two Mediterranean vole species: the role of patch-network structure and matrix composition.

    Science.gov (United States)

    Pita, Ricardo; Lambin, Xavier; Mira, António; Beja, Pedro

    2016-09-01

    According to ecological theory, the coexistence of competitors in patchy environments may be facilitated by hierarchical spatial segregation along axes of environmental variation, but empirical evidence is limited. Cabrera and water voles show a metapopulation-like structure in Mediterranean farmland, where they are known to segregate along space, habitat, and time axes within habitat patches. Here, we assess whether segregation also occurs among and within landscapes, and how this is influenced by patch-network and matrix composition. We surveyed 75 landscapes, each covering 78 ha, where we mapped all habitat patches potentially suitable for Cabrera and water voles, and the area effectively occupied by each species (extent of occupancy). The relatively large water vole tended to be the sole occupant of landscapes with high habitat amount but relatively low patch density (i.e., with a few large patches), and with a predominantly agricultural matrix, whereas landscapes with high patch density (i.e., many small patches) and low agricultural cover, tended to be occupied exclusively by the small Cabrera vole. The two species tended to co-occur in landscapes with intermediate patch-network and matrix characteristics, though their extents of occurrence were negatively correlated after controlling for environmental effects. In combination with our previous studies on the Cabrera-water vole system, these findings illustrated empirically the occurrence of hierarchical spatial segregation, ranging from within-patches to among-landscapes. Overall, our study suggests that recognizing the hierarchical nature of spatial segregation patterns and their major environmental drivers should enhance our understanding of species coexistence in patchy environments.

  7. A genome-wide, fine-scale map of natural pigmentation variation in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Héloïse Bastide

    2013-06-01

    Full Text Available Various approaches can be applied to uncover the genetic basis of natural phenotypic variation, each with their specific strengths and limitations. Here, we use a replicated genome-wide association approach (Pool-GWAS to fine-scale map genomic regions contributing to natural variation in female abdominal pigmentation in Drosophila melanogaster, a trait that is highly variable in natural populations and highly heritable in the laboratory. We examined abdominal pigmentation phenotypes in approximately 8000 female European D. melanogaster, isolating 1000 individuals with extreme phenotypes. We then used whole-genome Illumina sequencing to identify single nucleotide polymorphisms (SNPs segregating in our sample, and tested these for associations with pigmentation by contrasting allele frequencies between replicate pools of light and dark individuals. We identify two small regions near the pigmentation genes tan and bric-à-brac 1, both corresponding to known cis-regulatory regions, which contain SNPs showing significant associations with pigmentation variation. While the Pool-GWAS approach suffers some limitations, its cost advantage facilitates replication and it can be applied to any non-model system with an available reference genome.

  8. Investigations of fine-scale phylogeography in Tigriopus californicus reveal historical patterns of population divergence

    Directory of Open Access Journals (Sweden)

    Ladner Jason T

    2009-06-01

    Full Text Available Abstract Background The intertidal copepod Tigriopus californicus is a model for studying the process of genetic divergence in allopatry and for probing the nature of genetic changes that lead to reproductive isolation. Although previous studies have revealed a pattern of remarkably high levels of genetic divergence between the populations of this species at several spatial scales, it is not clear what types of historical processes are responsible. Particularly lacking are data that can yield insights into population history from the finest scales of geographic resolution. Results Sequence variation in both cytochrome b (CYTB, mtDNA and the rieske iron-sulfur protein (RISP, nuclear are examined at a fine scale within four different regions for populations of T. californicus. High levels of genetic divergence are seen for both genes at the broader scale, and genetic subdivision is apparent at nearly all scales in these populations for these two genes. Patterns of polymorphism and divergence in both CYTB and RISP suggest that selection may be leading to non-neutral evolution of these genes in several cases but a pervasive pattern of neither selection nor coadaptation is seen for these markers. Conclusion The use of sequence data at a fine-scale of resolution in this species has provided novel insights into the processes that have resulted in the accumulation of genetic divergence among populations. This divergence is likely to result from an interplay between a limited dispersal ability for this copepod and the temporal instability of copepod habitat. Both shorter-term processes such as the extinction/recolonization dynamics of copepod pools and longer-term processes such as geological uplift of coastline and sea level changes appear to have impacted the patterns of differentiation. Some patterns of sequence variation are consistent with selection acting upon the loci used in this study; however, it appears that most phylogeographic patterns are

  9. Male meiotic segregation analyses of peri- and paracentric inversions in the pig species.

    Science.gov (United States)

    Massip, K; Bonnet, N; Calgaro, A; Billoux, S; Baquié, V; Mary, N; Bonnet-Garnier, A; Ducos, A; Yerle, M; Pinton, A

    2009-01-01

    Inversions are well-known structural chromosomal rearrangements in humans and pigs. Such rearrangements generally have no effect on the carriers' phenotype. However, the presence of an inversion can lead to spermatogenesis impairments and to the production of unbalanced (recombinant) gametes, responsible for early miscarriages, stillbirth, or congenital abnormalities. Sperm samples from boars heterozygote for pericentric inv(2)(p1.1;q1.1), inv(2) (p1.1;q2.1), inv(1)(p2.1;q2.10), or inv(1)(p2.4;q2.9), as well as for paracentric inv(2)(q1.3;q2.5) or inv(1)(q1.2;q2.4) were analyzed using sperm FISH (fluorescent in situ hybridization on decondensed sperm heads) to determine the male meiotic segregation profiles of the rearrangements. Furthermore, the availability of sperm samples for 2 unrelated carriers of inv(2)(p1.1;q1.1) allowed us to check for the occurrence of inter-individual variability of the rates of unbalanced meiotic products for this rearrangement. The estimated proportions of recombinant gametes were very low for all the inversions studied (0.62%, 1.30%, 3.05%, 1.27%, 4.12% and 0.84%, respectively), albeit significantly higher than the control. The rearrangements should therefore have very little impact on the reproductive performance of the carriers. No difference was found between the 2 carriers of inv(2)(p1.1;q1.1), suggesting a lack of inter-individual variability for this rearrangement. Overall, no significant correlation was found between the sizes of the inverted fragments and the proportions of recombinant (unbalanced) gametes for the 6 inversions studied. This is in contradiction with most human results. Further studies (pairing and recombination analysis using immunostaining techniques) should be carried out to elucidate the origin of such an inter-species difference.

  10. Sexual recombination in Colletotrichum lindemuthianum occurs on a fine scale.

    Science.gov (United States)

    Souza, E A; Camargo, O A; Pinto, J M A

    2010-09-08

    Glomerella cingulata f. sp phaseoli is the sexual phase of the fungus Colletotrichum lindemuthianum, the causal agent of common bean anthracnose. This fungus is of great concern, because it causes large economic losses in common bean crops. RAPD markers of five populations of G. cingulata f. sp phaseoli from two Brazilian states were analyzed to determine if this population possesses the sexual reproductive potential to generate the genetic variation that is observed in this phytopathogen. We identified 128 polymorphic bands, amplified by 28 random primers. The estimates of genetic similarity in this analysis ranged from 0.43 to 1.00, and the dendrogram generated from analysis of all genotypes displayed five principal groups, coinciding with the five populations. Genetic differentiation was observed between the populations (GST=0.6455); 69% of the overall observed genetic variation was between individual populations and 31% of the variance was within the sub-populations. We identified significant levels of linkage disequilibrium in all populations. However, the values of the disequilibrium ranged from low to moderate, indicating that this pathogen maintains a genetic structure consistent with sexual reproduction. The mean contribution of sexual reproduction was determined by comparison of the amplitudes of genetic similarity of isolates from sexual and asexual phases. These results support the hypothesis that recombination plays an important role in determining the amplitude of variability in this pathogen population and that this determination occurs on a fine scale.

  11. Forest age correlates with fine-scale spatial structure of Matsutake mycorrhizas.

    Science.gov (United States)

    Amend, Anthony; Keeley, Sterling; Garbelotto, Matteo

    2009-05-01

    Examining the fine-scale spatial structure of fungal populations can tell us much about how individual species reproduce and disperse throughout natural landscapes. Here we study the fine-scale genetic structure of Tricholoma matsutake, a prized edible and medicinal mushroom, by systematic sampling of mycorrhizas within fairy rings in 50-y-old and old-growth forests in two villages. Using single nucleotide polymorphism DNA markers we show that mycorrhizas in both forest age classes in both villages showed high levels of genotypic diversity, consistent with a reproductive life history predominated by outcrossing via basidiospore dispersal. Both the percentage of polymorphic loci within fairy rings, as well as genotype diversity were higher in old-growth compared to 50-y-old forests. Fifty-year-old forests showed significant spatial autocorrelation between pairs of mycorrhizas up to 42m, and a pattern consistent isolation-by-distance structure. Spatial patterns in old-growth forests were random. Furthermore, AMOVA analysis indicates that 11% of molecular variance in 50-y-old forests is partitioned between villages, whereas no significant variance is partitioned between villages in old-growth forests. We conclude that populations of T. matsutake in 50-y-old forests are the result of a founder effect maintained by local inoculation sources. This pattern attenuates as forests age and accumulate inocula from more distance sources. We speculate on how genetic mosaicism within T. matsutake fairy rings may structure populations within a chronosequence. Finally, we discuss how population spatial dynamics and dispersal strategy in T. matsutake contrast with other ectomycorrhizal species.

  12. Competition and habitat suitability: small-scale segregation underpins large-scale coexistence of key species on temperate rocky shores.

    Science.gov (United States)

    Firth, Louise Bridget; Crowe, Tasman P

    2010-01-01

    Identifying the mechanisms that underpin species richness is one of the central issues of community ecology. On rocky shores in north-western Europe, two key limpet species coexist on the mid- and low shore but are segregated at small scales with respect to habitat. Shortterm and long-term experiments were done to test whether habitat suitability or habitat-specific competition drives the small-scale segregation of these species and therefore underpins their coexistence at larger spatial scales. In a controlled short-term experiment, Patella vulgata was transplanted onto open rock and into pools that either contained Patella ulyssiponensis and/or their mucus or from which P. ulyssiponensis and/or their mucus had been removed. After 2 days, P. vulgata remained in all experimental plots in similar numbers irrespective of treatment indicating that there was no negative response to P. ulyssiponensis, mucus or the pool habitat. In a long-term experiment, cage enclosures containing both species were set up in pools and on open rock over a 6-month period. P. vulgata grew equally well on both open rock and in pools but suffered higher mortality in pools. P. ulyssiponensis showed lower growth rate and higher mortality on open rock than in pools. P. ulyssiponensis exhibited increased growth in higher intraspecific densities on open rock and reduced growth in higher intraspecific densities in pools, indicating some degree of intraspecific facilitation on open rock and intraspecific competition in pools. There was no evidence of interspecific competition either in the short term or in the long term. Results revealed that habitat suitability was the mechanism causing segregation of these species at smaller spatial scales enabling them to coexist at larger spatial scales. Conflicting results in the short-term and long-term experiments highlight the importance of considering the correct temporal extent for experimental tests of hypotheses.

  13. Outlier SNP markers reveal fine-scale genetic structuring across European hake populations (Merluccius merluccius).

    Science.gov (United States)

    Milano, Ilaria; Babbucci, Massimiliano; Cariani, Alessia; Atanassova, Miroslava; Bekkevold, Dorte; Carvalho, Gary R; Espiñeira, Montserrat; Fiorentino, Fabio; Garofalo, Germana; Geffen, Audrey J; Hansen, Jakob H; Helyar, Sarah J; Nielsen, Einar E; Ogden, Rob; Patarnello, Tomaso; Stagioni, Marco; Tinti, Fausto; Bargelloni, Luca

    2014-01-01

    Shallow population structure is generally reported for most marine fish and explained as a consequence of high dispersal, connectivity and large population size. Targeted gene analyses and more recently genome-wide studies have challenged such view, suggesting that adaptive divergence might occur even when neutral markers provide genetic homogeneity across populations. Here, 381 SNPs located in transcribed regions were used to assess large- and fine-scale population structure in the European hake (Merluccius merluccius), a widely distributed demersal species of high priority for the European fishery. Analysis of 850 individuals from 19 locations across the entire distribution range showed evidence for several outlier loci, with significantly higher resolving power. While 299 putatively neutral SNPs confirmed the genetic break between basins (F(CT) = 0.016) and weak differentiation within basins, outlier loci revealed a dramatic divergence between Atlantic and Mediterranean populations (F(CT) range 0.275-0.705) and fine-scale significant population structure. Outlier loci separated North Sea and Northern Portugal populations from all other Atlantic samples and revealed a strong differentiation among Western, Central and Eastern Mediterranean geographical samples. Significant correlation of allele frequencies at outlier loci with seawater surface temperature and salinity supported the hypothesis that populations might be adapted to local conditions. Such evidence highlights the importance of integrating information from neutral and adaptive evolutionary patterns towards a better assessment of genetic diversity. Accordingly, the generated outlier SNP data could be used for tackling illegal practices in hake fishing and commercialization as well as to develop explicit spatial models for defining management units and stock boundaries.

  14. Image-Based Fine-Scale Infrastructure Monitoring

    Science.gov (United States)

    Detchev, Ivan Denislavov

    Monitoring the physical health of civil infrastructure systems is an important task that must be performed frequently in order to ensure their serviceability and sustainability. Additionally, laboratory experiments where individual system components are tested on the fine-scale level provide essential information during the structural design process. This type of inspection, i.e., measurements of deflections and/or cracks, has traditionally been performed with instrumentation that requires access to, or contact with, the structural element being tested; performs deformation measurements in only one dimension or direction; and/or provides no permanent visual record. To avoid the downsides of such instrumentation, this dissertation proposes a remote sensing approach based on a photogrammetric system capable of three-dimensional reconstruction. The proposed system is low-cost, consists of off-the-shelf components, and is capable of reconstructing objects or surfaces with homogeneous texture. The scientific contributions of this research work address the drawbacks in currently existing literature. Methods for in-situ multi-camera system calibration and system stability analysis are proposed in addition to methods for deflection/displacement monitoring, and crack detection and characterization in three dimensions. The mathematical model for the system calibration is based on a single or multiple reference camera(s) and built-in relative orientation constraints where the interior orientation and the mounting parameters for all cameras are explicitly estimated. The methods for system stability analysis can be used to comprehensively check for the cumulative impact of any changes in the system parameters. They also provide a quantitative measure of this impact on the reconstruction process in terms of image space units. Deflection/displacement monitoring of dynamic surfaces in three dimensions is achieved with the system by performing an innovative sinusoidal fitting

  15. 75 FR 60407 - Gulf of the Farallones National Marine Sanctuary Permit Application Project Titled: Fine Scale...

    Science.gov (United States)

    2010-09-30

    ... Application Project Titled: Fine Scale, Long-Term Tracking of Adult White Sharks AGENCY: Office of National...://farallones.noaa.gov/eco/sharks/pdf/ea_mcsi_permit2009.pdf . DATES: Comments on this draft...

  16. Document Fine Scale Linkage Areas and Conservation Delivery of the Northern Rockies in US and Canada

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Assessment of fine-scale habitat linkages in the Northern Rockies through use of biological DNA, telemetry and ecological modeling to predict critical linkages for...

  17. Fine-Scale Bacterial Beta Diversity within a Complex Ecosystem (Zodletone Spring, OK, USA): The Role of the Rare Biosphere

    Science.gov (United States)

    Youssef, Noha H.; Couger, M. B.; Elshahed, Mostafa S.

    2010-01-01

    Background The adaptation of pyrosequencing technologies for use in culture-independent diversity surveys allowed for deeper sampling of ecosystems of interest. One extremely well suited area of interest for pyrosequencing-based diversity surveys that has received surprisingly little attention so far, is examining fine scale (e.g. micrometer to millimeter) beta diversity in complex microbial ecosystems. Methodology/Principal Findings We examined the patterns of fine scale Beta diversity in four adjacent sediment samples (1mm apart) from the source of an anaerobic sulfide and sulfur rich spring (Zodletone spring) in southwestern Oklahoma, USA. Using pyrosequencing, a total of 292,130 16S rRNA gene sequences were obtained. The beta diversity patterns within the four datasets were examined using various qualitative and quantitative similarity indices. Low levels of Beta diversity (high similarity indices) were observed between the four samples at the phylum-level. However, at a putative species (OTU0.03) level, higher levels of beta diversity (lower similarity indices) were observed. Further examination of beta diversity patterns within dominant and rare members of the community indicated that at the putative species level, beta diversity is much higher within rare members of the community. Finally, sub-classification of rare members of Zodletone spring community based on patterns of novelty and uniqueness, and further examination of fine scale beta diversity of each of these subgroups indicated that members of the community that are unique, but non novel showed the highest beta diversity within these subgroups of the rare biosphere. Conclusions/Significance The results demonstrate the occurrence of high inter-sample diversity within seemingly identical samples from a complex habitat. We reason that such unexpected diversity should be taken into consideration when exploring gamma diversity of various ecosystems, as well as planning for sequencing-intensive metagenomic

  18. Fine-scale bacterial beta diversity within a complex ecosystem (Zodletone Spring, OK, USA: the role of the rare biosphere.

    Directory of Open Access Journals (Sweden)

    Noha H Youssef

    Full Text Available BACKGROUND: The adaptation of pyrosequencing technologies for use in culture-independent diversity surveys allowed for deeper sampling of ecosystems of interest. One extremely well suited area of interest for pyrosequencing-based diversity surveys that has received surprisingly little attention so far, is examining fine scale (e.g. micrometer to millimeter beta diversity in complex microbial ecosystems. METHODOLOGY/PRINCIPAL FINDINGS: We examined the patterns of fine scale Beta diversity in four adjacent sediment samples (1mm apart from the source of an anaerobic sulfide and sulfur rich spring (Zodletone spring in southwestern Oklahoma, USA. Using pyrosequencing, a total of 292,130 16S rRNA gene sequences were obtained. The beta diversity patterns within the four datasets were examined using various qualitative and quantitative similarity indices. Low levels of Beta diversity (high similarity indices were observed between the four samples at the phylum-level. However, at a putative species (OTU(0.03 level, higher levels of beta diversity (lower similarity indices were observed. Further examination of beta diversity patterns within dominant and rare members of the community indicated that at the putative species level, beta diversity is much higher within rare members of the community. Finally, sub-classification of rare members of Zodletone spring community based on patterns of novelty and uniqueness, and further examination of fine scale beta diversity of each of these subgroups indicated that members of the community that are unique, but non novel showed the highest beta diversity within these subgroups of the rare biosphere. CONCLUSIONS/SIGNIFICANCE: The results demonstrate the occurrence of high inter-sample diversity within seemingly identical samples from a complex habitat. We reason that such unexpected diversity should be taken into consideration when exploring gamma diversity of various ecosystems, as well as planning for sequencing

  19. Strict sex-specific mtDNA segregation in the germ line of the DUI species Venerupis philippinarum (Bivalvia: Veneridae).

    Science.gov (United States)

    Ghiselli, Fabrizio; Milani, Liliana; Passamonti, Marco

    2011-02-01

    Doubly Uniparental Inheritance (DUI) is one of the most striking exceptions to the common rule of standard maternal inheritance of metazoan mitochondria. In DUI, two mitochondrial genomes are present, showing different transmission routes, one through eggs (F-type) and the other through sperm (M-type). In this paper, we report results from a multiplex real-time quantitative polymerase chain reaction analysis on the Manila clam Venerupis philippinarum (formerly Tapes philippinarum). We quantified M- and F-types in somatic tissues, gonads, and gametes. Nuclear and external reference sequences were used, and the whole experimental process was designed to avoid any possible cross-contamination. In most male somatic tissues, the M-type is largely predominant: This suggests that the processes separating sex-linked mitochondrial DNAs (mtDNAs) in somatic tissues are less precise than in other DUI species. In the germ line, we evidenced a strict sex-specific mtDNA segregation because both sperm and eggs do carry exclusively M- and F-types, respectively, an observation that is in contrast with a previous analysis on Mytilus galloprovincialis. More precisely, whereas two mtDNAs are present in the whole gonad, only the sex-specific one is detected in gametes. Because of this, we propose that the mtDNA transmission is achieved through a three-checkpoint process in V. philippinarum. The cytological mechanisms of male mitochondria segregation in males and degradation in females during the embryo development (here named Checkpoint #1 and Checkpoint #2) are already well known for DUI species; a Checkpoint #3 would act when primordial germ cells (PGCs) are first formed and would work in both males and females. We believe that Checkpoint #3 is a mere variation of the "mitochondrial bottleneck" in species with standard maternal inheritance, established when their PGCs separate during embryo cleavage.

  20. Fine-Scale Relief in the Amazon Drives Large Scale Ecohydrological Processes

    Science.gov (United States)

    Nobre, A. D.; Cuartas, A.; Hodnett, M.; Saleska, S. R.

    2014-12-01

    Access to soil water by roots is a key ecophysiological factor for plant productivity in natural systems. Periodically during dry seasons or critically during episodic climate droughts, shortage of water supply can reduce or severely impair plant life. At the other extreme persistent soil waterlogging will limit root respiration and restrict local establishment to adapted species, usually leading to stunted and less productive communities. Soil-water availability is therefore a very important climate variable controlling plant physiology and ecosystem dynamics. Terra-firme, the non-seasonally floodable terrain that covers 82% of the landscape in Amazonia,[1] supports the most massive part of the rainforest ecosystem. The availability of soil water data for terra-firme is scant and very coarse. This lack of data has hampered observational and modeling studies aiming to develop a large-scale integrative ecohydrological picture of Amazonia and its vulnerability to climate change. We have mapped the Amazon basin with a new terrain model developed in our group (HAND, Height Above the Nearest drainage[2]), delineating soil water environments using topographical data from the SRTM digital elevation model (250 m horizontal interpolated resolution). The preliminary results show that more than 50% of Terra-firme has the water table very close to the surface (up to 2 m deep), while the remainder of the upland landscape has variable degree of dependence on non-saturated soil (vadose layer). The mapping also shows extremely heterogeneous patterns of fine-scale relief across the basin, which implies complex ecohydrological regional forcing on the forest physiology. Ecoclimate studies should therefore take into account fine-scale relief and its implications for soil-water availability to plant processes. [1] Melack, J. M., & Hess, L. L. (2011). Remote sensing of the distribution and extent of wetlands in the Amazon basin. In W. J. Junk & M. Piedade (Eds.), Amazonian floodplain

  1. Effects of currents and tides on fine-scale use of marine bird habitats in a Southeast Alaska hotspot

    Science.gov (United States)

    Drew, Gary S.; Piatt, John F.; Hill, David J.

    2013-01-01

    Areas with high species richness have become focal points in the establishment of marine protected areas, but an understanding of the factors that support this diversity is still incomplete. In coastal areas, tidal currents—modulated by bathymetry and manifested in variable speeds—are a dominant physical feature of the environment. However, difficulties resolving tidally affected currents and depths at fine spatial-temporal scales have limited our ability to understand their influence the distribution of marine birds. We used a hydrographic model of the water mass in Glacier Bay, Alaska to link depths and current velocities with the locations of 15 common marine bird species observed during fine-scale boat-based surveys of the bay conducted during June of four consecutive years (2000-2003). Marine birds that forage on the bottom tended to occupy shallow habitats with slow-moving currents; mid-water foragers used habitats with intermediate depths and current speeds; and surface-foraging species tended to use habitats with fast-moving, deep waters. Within foraging groups there was variability among species in their use of habitats. While species obligated to foraging near bottom were constrained to use similar types of habitat, species in the mid-water foraging group were associated with a wider range of marine habitat characteristics. Species also showed varying levels of site use depending on tide stage. The dramatic variability in bottom topography—especially the presence of numerous sills, islands, headlands and channels—and large tidal ranges in Glacier Bay create a wide range of current-affected fine-scale foraging habitats that may contribute to the high diversity of marine bird species found there.

  2. Restricted gene flow and fine-scale population structuring in tool using New Caledonian crows

    Science.gov (United States)

    Rutz, C.; Ryder, T. B.; Fleischer, R. C.

    2012-04-01

    New Caledonian crows Corvus moneduloides are the most prolific avian tool users. It has been suggested that some aspects of their complex tool use behaviour are under the influence of cultural processes, involving the social transmission—and perhaps even progressive refinement—of tool designs. Using microsatellite and mt-haplotype profiling of crows from three distinct habitats (dry forest, farmland and beachside habitat), we show that New Caledonian crow populations can exhibit significant fine-scale genetic structuring. Our finding that some sites of genetic and/or cultural isolation of crow groups. Restricted movement of birds between local populations at such small spatial scales, especially across habitat boundaries, illustrates how specific tool designs could be preserved over time, and how tool technologies of different crow groups could diverge due to drift and local selection pressures. Young New Caledonian crows have an unusually long juvenile dependency period, during which they acquire complex tool-related foraging skills. We suggest that the resulting delayed natal dispersal drives population-divergence patterns in this species. Our work provides essential context for future studies that examine the genetic makeup of crow populations across larger geographic areas, including localities with suspected cultural differences in crow tool technologies.

  3. Restricted gene flow and fine-scale population structuring in tool using New Caledonian crows.

    Science.gov (United States)

    Rutz, C; Ryder, T B; Fleischer, R C

    2012-04-01

    New Caledonian crows Corvus moneduloides are the most prolific avian tool users. It has been suggested that some aspects of their complex tool use behaviour are under the influence of cultural processes, involving the social transmission-and perhaps even progressive refinement-of tool designs. Using microsatellite and mt-haplotype profiling of crows from three distinct habitats (dry forest, farmland and beachside habitat), we show that New Caledonian crow populations can exhibit significant fine-scale genetic structuring. Our finding that some sites of crow groups. Restricted movement of birds between local populations at such small spatial scales, especially across habitat boundaries, illustrates how specific tool designs could be preserved over time, and how tool technologies of different crow groups could diverge due to drift and local selection pressures. Young New Caledonian crows have an unusually long juvenile dependency period, during which they acquire complex tool-related foraging skills. We suggest that the resulting delayed natal dispersal drives population-divergence patterns in this species. Our work provides essential context for future studies that examine the genetic makeup of crow populations across larger geographic areas, including localities with suspected cultural differences in crow tool technologies.

  4. Cerambycid Beetle Species with Similar Pheromones are Segregated by Phenology and Minor Pheromone Components.

    Science.gov (United States)

    Mitchell, Robert F; Reagel, Peter F; Wong, Joseph C H; Meier, Linnea R; Silva, Weliton Dias; Mongold-Diers, Judith; Millar, Jocelyn G; Hanks, Lawrence M

    2015-05-01

    Recent research has shown that volatile sex and aggregation-sex pheromones of many species of cerambycid beetles are highly conserved, with sympatric and synchronic species that are closely related (i.e., congeners), and even more distantly related (different subfamilies), using the same or similar pheromones. Here, we investigated mechanisms by which cross attraction is averted among seven cerambycid species that are native to eastern North America and active as adults in spring: Anelaphus pumilus (Newman), Cyrtophorus verrucosus (Olivier), Euderces pini (Olivier), Neoclytus caprea (Say), and the congeners Phymatodes aereus (Newman), P. amoenus (Say), and P. varius (F.). Males of these species produce (R)-3-hydroxyhexan-2-one as their dominant or sole pheromone component. Our field bioassays support the hypothesis that cross attraction between species is averted or at least minimized by differences among species in seasonal phenology and circadian flight periods of adults, and/or by minor pheromone components that act as synergists for conspecifics and antagonists for heterospecifics.

  5. Fine-scale movement decisions of tropical forest birds in a fragmented landscape.

    Science.gov (United States)

    Gillies, Cameron S; Beyer, Hawthorne L; St Clair, Colleen Cassady

    2011-04-01

    The persistence of forest-dependent species in fragmented landscapes is fundamentally linked to the movement of individuals among subpopulations. The paths taken by dispersing individuals can be considered a series of steps built from individual route choices. Despite the importance of these fine-scale movement decisions, it has proved difficult to collect such data that reveal how forest birds move in novel landscapes. We collected unprecedented route information about the movement of translocated forest birds from two species in the highly fragmented tropical dry forest of Costa Rica. In this pasture-dominated landscape, forest remains in patches or riparian corridors, with lesser amounts of living fencerows and individual trees or "stepping stones." We used step selection functions to quantify how route choice was influenced by these habitat elements. We found that the amount of risk these birds were willing to take by crossing open habitat was context dependent. The forest-specialist Barred Antshrike (Thamnophilus doliatus) exhibited stronger selection for forested routes when moving in novel landscapes distant from its territory relative to locations closer to its territory. It also selected forested routes when its step originated in forest habitat. It preferred steps ending in stepping stones when the available routes had little forest cover, but avoided them when routes had greater forest cover. The forest-generalist Rufous-naped Wren (Campylorhynchus rufinucha) preferred steps that contained more pasture, but only when starting from non-forest habitats. Our results showed that forested corridors (i.e., riparian corridors) best facilitated the movement of a sensitive forest specialist through this fragmented landscape. They also suggested that stepping stones can be important in highly fragmented forests with little remaining forest cover. We expect that naturally dispersing birds and species with greater forest dependence would exhibit even stronger

  6. Spatial Segregation and Aggregation of Ectomycorrhizal and Root-Endophytic Fungi in the Seedlings of Two Quercus Species

    Science.gov (United States)

    Yamamoto, Satoshi; Sato, Hirotoshi; Tanabe, Akifumi S.; Hidaka, Amane; Kadowaki, Kohmei; Toju, Hirokazu

    2014-01-01

    Diverse clades of mycorrhizal and endophytic fungi are potentially involved in competitive or facilitative interactions within host-plant roots. We investigated the potential consequences of these ecological interactions on the assembly process of root-associated fungi by examining the co-occurrence of pairs of fungi in host-plant individuals. Based on massively-parallel pyrosequencing, we analyzed the root-associated fungal community composition for each of the 249 Quercus serrata and 188 Quercus glauca seedlings sampled in a warm-temperate secondary forest in Japan. Pairs of fungi that co-occurred more or less often than expected by chance were identified based on randomization tests. The pyrosequencing analysis revealed that not only ectomycorrhizal fungi but also endophytic fungi were common in the root-associated fungal community. Intriguingly, specific pairs of these ectomycorrhizal and endophytic fungi showed spatially aggregated patterns, suggesting the existence of facilitative interactions between fungi in different functional groups. Due to the large number of fungal pairs examined, many of the observed aggregated/segregated patterns with very low P values (e.g., fungi could influence each other through interspecific competitive/facilitative interactions in root. To test the potential of host-plants' control of fungus–fungus ecological interactions in roots, we further examined whether the aggregated/segregated patterns could vary depending on the identity of host plant species. Potentially due to the physiological properties shared between the congeneric host plant species, the sign of hosts' control was not detected in the present study. The pyrosequencing-based randomization analyses shown in this study provide a platform of the high-throughput investigation of fungus–fungus interactions in plant root systems. PMID:24801150

  7. Spatial segregation and aggregation of ectomycorrhizal and root-endophytic fungi in the seedlings of two Quercus species.

    Science.gov (United States)

    Yamamoto, Satoshi; Sato, Hirotoshi; Tanabe, Akifumi S; Hidaka, Amane; Kadowaki, Kohmei; Toju, Hirokazu

    2014-01-01

    Diverse clades of mycorrhizal and endophytic fungi are potentially involved in competitive or facilitative interactions within host-plant roots. We investigated the potential consequences of these ecological interactions on the assembly process of root-associated fungi by examining the co-occurrence of pairs of fungi in host-plant individuals. Based on massively-parallel pyrosequencing, we analyzed the root-associated fungal community composition for each of the 249 Quercus serrata and 188 Quercus glauca seedlings sampled in a warm-temperate secondary forest in Japan. Pairs of fungi that co-occurred more or less often than expected by chance were identified based on randomization tests. The pyrosequencing analysis revealed that not only ectomycorrhizal fungi but also endophytic fungi were common in the root-associated fungal community. Intriguingly, specific pairs of these ectomycorrhizal and endophytic fungi showed spatially aggregated patterns, suggesting the existence of facilitative interactions between fungi in different functional groups. Due to the large number of fungal pairs examined, many of the observed aggregated/segregated patterns with very low P values (e.g., fungi could influence each other through interspecific competitive/facilitative interactions in root. To test the potential of host-plants' control of fungus-fungus ecological interactions in roots, we further examined whether the aggregated/segregated patterns could vary depending on the identity of host plant species. Potentially due to the physiological properties shared between the congeneric host plant species, the sign of hosts' control was not detected in the present study. The pyrosequencing-based randomization analyses shown in this study provide a platform of the high-throughput investigation of fungus-fungus interactions in plant root systems.

  8. Modelling and visualizing fine-scale linkage disequilibrium structure

    DEFF Research Database (Denmark)

    Edwards, David

    2013-01-01

    Background Detailed study of genetic variation at the population level in humans and other species is now possible due to the availability of large sets of single nucleotide polymorphism data. Alleles at two or more loci are said to be in linkage disequilibrium (LD) when they are correlated...... the methods they are applied to data obtained by genotyping 8341 pigs. It is found that roughly 20% of the porcine genome exhibits complex LD patterns, forming islands of relatively high genetic diversity. Conclusions The proposed algorithm is efficient and makes it feasible to estimate and visualize...

  9. Crossing Methods and Cultivation Conditions for Rapid Production of Segregating Populations in Three Grain Amaranth Species.

    Science.gov (United States)

    Stetter, Markus G; Zeitler, Leo; Steinhaus, Adrian; Kroener, Karoline; Biljecki, Michelle; Schmid, Karl J

    2016-01-01

    Grain amaranths (Amaranthus spp.) have been cultivated for thousands of years in Central and South America. Their grains are of high nutritional value, but the low yield needs to be increased by selection of superior genotypes from genetically diverse breeding populations. Amaranths are adapted to harsh conditions and can be cultivated on marginal lands although little is known about their physiology. The development of controlled growing conditions and efficient crossing methods is important for research on and improvement of this ancient crop. Grain amaranth was domesticated in the Americas and is highly self-fertilizing with a large inflorescence consisting of thousands of very small flowers. We evaluated three different crossing methods (open pollination, hot water emasculation and hand emasculation) for their efficiency in amaranth and validated them with genetic markers. We identified cultivation conditions that allow an easy control of flowering time by day length manipulation and achieved flowering times of 4 weeks and generation times of 2 months. All three different crossing methods successfully produced hybrid F1 offspring, but with different success rates. Open pollination had the lowest (10%) and hand emasculation the highest success rate (74%). Hot water emasculation showed an intermediate success rate (26%) with a maximum of 94% success. It is simple to perform and suitable for a more large-scale production of hybrids. We further evaluated 11 single nucleotide polymorphism (SNP) markers and found that they were sufficient to validate all crosses of the genotypes used in this study for intra- and interspecific hybridizations. Despite its very small flowers, crosses in amaranth can be carried out efficiently and evaluated with inexpensive SNP markers. Suitable growth conditions strongly reduce the generation time and allow the control of plant height, flowering time, and seed production. In combination, this enables the rapid production of segregating

  10. Crossing methods and cultivation conditions for rapid production of segregating populations in three grain amaranth species

    Directory of Open Access Journals (Sweden)

    Markus G Stetter

    2016-06-01

    production of segregating populations which makes amaranth an attractive model for basic plant research but also facilitates further the improvement of this ancient crop by plant breeding.

  11. Spatial Downscaling of TRMM Precipitation Using Geostatistics and Fine Scale Environmental Variables

    Directory of Open Access Journals (Sweden)

    No-Wook Park

    2013-01-01

    Full Text Available A geostatistical downscaling scheme is presented and can generate fine scale precipitation information from coarse scale Tropical Rainfall Measuring Mission (TRMM data by incorporating auxiliary fine scale environmental variables. Within the geostatistical framework, the TRMM precipitation data are first decomposed into trend and residual components. Quantitative relationships between coarse scale TRMM data and environmental variables are then estimated via regression analysis and used to derive trend components at a fine scale. Next, the residual components, which are the differences between the trend components and the original TRMM data, are then downscaled at a target fine scale via area-to-point kriging. The trend and residual components are finally added to generate fine scale precipitation estimates. Stochastic simulation is also applied to the residual components in order to generate multiple alternative realizations and to compute uncertainty measures. From an experiment using a digital elevation model (DEM and normalized difference vegetation index (NDVI, the geostatistical downscaling scheme generated the downscaling results that reflected detailed characteristics with better predictive performance, when compared with downscaling without the environmental variables. Multiple realizations and uncertainty measures from simulation also provided useful information for interpretations and further environmental modeling.

  12. Fine-scale spatial genetic structure in predominantly selfing plants with limited seed dispersal: A rule or exception?

    Directory of Open Access Journals (Sweden)

    Sergei Volis

    2016-04-01

    Full Text Available Gene flow at a fine scale is still poorly understood despite its recognized importance for plant population demographic and genetic processes. We tested the hypothesis that intensity of gene flow will be lower and strength of spatial genetic structure (SGS will be higher in more peripheral populations because of lower population density. The study was performed on the predominantly selfing Avena sterilis and included: (1 direct measurement of dispersal in a controlled environment; and (2 analyses of SGS in three natural populations, sampled in linear transects at fixed increasing inter-plant distances. We found that in A. sterilis major seed dispersal is by gravity in close (less than 2 m vicinity of the mother plant, with a minor additional effect of wind. Analysis of SGS with six nuclear SSRs revealed a significant autocorrelation for the distance class of 1 m only in the most peripheral desert population, while in the two core populations with Mediterranean conditions, no genetic structure was found. Our results support the hypothesis that intensity of SGS increases from the species core to periphery as a result of decreased within-population gene flow related to low plant density. Our findings also show that predominant self-pollination and highly localized seed dispersal lead to SGS at a very fine scale, but only if plant density is not too high.

  13. Finding your mate at a cocktail party: frequency separation promotes auditory stream segregation of concurrent voices in multi-species frog choruses.

    Directory of Open Access Journals (Sweden)

    Vivek Nityananda

    Full Text Available Vocal communication in crowded social environments is a difficult problem for both humans and nonhuman animals. Yet many important social behaviors require listeners to detect, recognize, and discriminate among signals in a complex acoustic milieu comprising the overlapping signals of multiple individuals, often of multiple species. Humans exploit a relatively small number of acoustic cues to segregate overlapping voices (as well as other mixtures of concurrent sounds, like polyphonic music. By comparison, we know little about how nonhuman animals are adapted to solve similar communication problems. One important cue enabling source segregation in human speech communication is that of frequency separation between concurrent voices: differences in frequency promote perceptual segregation of overlapping voices into separate "auditory streams" that can be followed through time. In this study, we show that frequency separation (ΔF also enables frogs to segregate concurrent vocalizations, such as those routinely encountered in mixed-species breeding choruses. We presented female gray treefrogs (Hyla chrysoscelis with a pulsed target signal (simulating an attractive conspecific call in the presence of a continuous stream of distractor pulses (simulating an overlapping, unattractive heterospecific call. When the ΔF between target and distractor was small (e.g., ≤3 semitones, females exhibited low levels of responsiveness, indicating a failure to recognize the target as an attractive signal when the distractor had a similar frequency. Subjects became increasingly more responsive to the target, as indicated by shorter latencies for phonotaxis, as the ΔF between target and distractor increased (e.g., ΔF = 6-12 semitones. These results support the conclusion that gray treefrogs, like humans, can exploit frequency separation as a perceptual cue to segregate concurrent voices in noisy social environments. The ability of these frogs to segregate

  14. Landscape relatedness: detecting contemporary fine-scale spatial structure in wild populations

    DEFF Research Database (Denmark)

    Norman, Anita J; Strønen, Astrid Vik; Fuglstad, Geir-Arne

    2017-01-01

    Context Methods for detecting contemporary, fine-scale population genetic structure in continuous populations are scarce. Yet such methods are vital for ecological and conservation studies, particularly under a changing landscape. Objectives Here we present a novel, spatially explicit method...... that we call landscape relatedness (LandRel). With this method, we aim to detect contemporary, fine-scale population structure that is sensitive to spatial and temporal changes in the landscape. Methods We interpolate spatially determined relatedness values based on SNP genotypes across the landscape...... population. Further analysis suggests that inbreeding has occurred in at least one of these areas. Conclusions LandRel enabled us to identify previously unknown fine-scale structuring in the population. These results will help direct future research efforts, conservation action and aid in the management...

  15. Segregation of Species-Specific Male Attractiveness in F2 Hybrid Lake Malawi Cichlid Fish

    Directory of Open Access Journals (Sweden)

    Ola Svensson

    2011-01-01

    Full Text Available Among the huge radiations of haplochromine cichlid fish in Lakes Malawi and Victoria, closely related species are often reproductively isolated via female mate choice although viable fertile hybrids can be produced when females are confined only with heterospecific males. We generated F2 hybrid males from a cross between a pair of closely related sympatric cichlid fish from Lake Malawi. Laboratory mate choice experiments using microsatellite paternity analysis demonstrated that F2 hybrid males differed significantly in their attractiveness to females of the two parental species, indicating heritable variation in traits involved in mate choice that may contribute to reproductive isolation between these species. We found no significant correlation between male mating success and any measurement of male colour pattern. A simple quantitative genetic model of reproductive isolation suggests that there may be as few as two chromosomal regions controlling species-specific attractiveness. We propose that adaptive radiation of Lake Malawi cichlids could be facilitated by the presence of genes with major effects on mate choice and reproductive isolation.

  16. Fine-scale spatial genetic structure and clonal distribution of the cold-water coral Lophelia pertusa

    Science.gov (United States)

    Dahl, M. P.; Pereyra, R. T.; Lundälv, T.; André, C.

    2012-12-01

    Determining the spatial genetic structure within and among cold-water coral populations is crucial to understanding population dynamics, assessing the resilience of cold-water coral communities and estimating genetic effects of habitat fragmentation for conservation. The spatial distribution of genetic diversity in natural populations depends on the species' mode of reproduction, and coral species often have a mixed strategy of sexual and asexual reproduction. We describe the clonal architecture of a cold-water coral reef and the fine-scale population genetic structure (Asexual reproduction was found to be a highly important mode of reproduction for L. pertusa: 35 genetic individuals were found on the largest reef, with the largest clone covering an area of nearly 300 m2.

  17. Molecular markers reveal spatially segregated cryptic species in a critically endangered fish, the common skate (Dipturus batis).

    Science.gov (United States)

    Griffiths, Andrew M; Sims, David W; Cotterell, Stephen P; El Nagar, Aliya; Ellis, Jim R; Lynghammar, Arve; McHugh, Matthew; Neat, Francis C; Pade, Nicolas G; Queiroz, Nuno; Serra-Pereira, Bárbara; Rapp, Toby; Wearmouth, Victoria J; Genner, Martin J

    2010-05-22

    Many sharks and skates are particularly vulnerable to overfishing because of their large size, slow growth, late maturity and low fecundity. In Europe dramatic population declines have taken place in common skate (Dipturus batis L.), one of the largest demersal fish in regional shelf seas, leading to extirpations from substantial parts of its former range. Here we report the discovery of cryptic species in common skate collected from the northeast Atlantic continental shelf. Data from nuclear microsatellite markers indicated two clearly distinct clades and phylogenetic analysis of mitochondrial DNA sequences demonstrated monophyly of each one of them. Capture locations showed evidence of strong spatial segregation, with one taxon occurring mainly in waters off the southern British Isles and around Rockall, while the other was restricted to more northerly shelf waters. These apparently cryptic species showed overlapping substrate and depth preferences, but distributional limits were closely related to temperature gradients, potentially indicating thermal limits to their distributions. This discovery of hidden diversity within a large, critically endangered marine vertebrate demonstrates how marine biodiversity can be underestimated, even in such a relatively well-studied and heavily exploited region.

  18. Fine-scale differences in diel activity among nocturnal freshwater planarias (Platyhelminthes: Tricladida

    Directory of Open Access Journals (Sweden)

    Cicolani Bruno

    2011-04-01

    , consistent with their photonegative characteristics. The fine-scale differences in diel behavior among these three triclad species may not be sufficient to allow coexistence in the wild, with the nonnative D. tigrina eventually displacing D. polychroa and P. tenuis in many European waters. The link between planarian diel rhythms and ecological characteristics are worth of further, detailed investigation.

  19. Inferring natural selection on fine-scale chromatin organization in yeast.

    Science.gov (United States)

    Babbitt, G A; Kim, Y

    2008-08-01

    Despite its potential role in the evolution of complex phenotypes, the detection of negative (purifying) and positive selection on noncoding regulatory sequence has been elusive because of the inherent difficulty in predicting the functional consequences of mutations on noncoding sequence. Because the functioning of regulatory sequence depends upon both chromatin configuration and cis-regulatory factor binding, we investigate the idea that the functional conservation of regulatory regions should be associated with the conservation of sequence-dependent bending properties of DNA that determine its affinity for the nucleosome. Recent advances in the computational prediction of sequence-dependent affinity to nucleosomes provide an opportunity to distinguish between neutral and nonneutral evolution of fine-scale chromatin organization. Here, a statistical test is presented for detecting evolutionary conservation and/or adaptive evolution of nucleosome affinity from interspecies comparisons of DNA sequences. Local nucleosome affinities of homologous sequences were calculated using 2 recently published methods. A randomization test was applied to sites of mutation to evaluate the similarity of DNA-nucleosome affinity between several closely related species of Saccharomyces yeast. For most of the genes we analyzed, the conservation of local nucleosome affinity was detected at a few distinct locations in the upstream noncoding region. Our results also demonstrate that different patterns of chromatin evolution have shaped DNA-nucleosome interaction at the core promoters of TATA-containing and TATA-less genes and that elevated purifying selection has maintained low affinity for nucleosome in the core promoters of the latter group. Across the entire yeast genome, DNA-nucleosome interaction was also discovered to be significantly more conserved in TATA-less genes compared with TATA-containing genes.

  20. Foraging segregation of two congeneric diving seabird species breeding on St. George Island, Bering Sea

    Science.gov (United States)

    Kokubun, Nobuo; Yamamoto, Takashi; Sato, Nobuhiko; Watanuki, Yutaka; Will, Alexis; Kitaysky, Alexander S.; Takahashi, Akinori

    2016-04-01

    Subarctic environmental changes are expected to affect the foraging ecology of marine top predators, but the response to such changes may vary among species if they use food resources differently. We examined the characteristics of foraging behavior of two sympatric congeneric diving seabird: common (Uria aalge: hereafter COMUs) and thick-billed (U. lomvia: hereafter TBMUs) murres breeding on St. George Island, located in the seasonal sea-ice region of the Bering Sea. We investigated their foraging trip and flight durations, diel patterns of dive depth, and underwater wing strokes, along with wing morphology and blood stable isotope signatures and stress hormones. Acceleration-temperature-depth loggers were attached to chick-guarding birds, and data were obtained from 7 COMUs and 12 TBMUs. Both species showed similar mean trip duration (13.2 h for COMUs and 10.5 h for TBMUs) and similar diurnal patterns of diving (frequent dives to various depths in the daytime and less frequent dives to shallow depths in the nighttime). During the daytime, the dive depths of COMUs had two peaks in shallow (18.1 m) and deep (74.2 m) depths, while those of TBMUs were 20.2 m and 59.7 m. COMUs showed more frequent wing strokes during the bottom phase of dives (1.90 s-1) than TBMUs (1.66 s-1). Fish occurred more frequently in the bill loads of COMUs (85 %) than those of TBMUs (56 %). The δ15N value of blood was significantly higher in COMUs (14.5 ‰) than in TBMUs (13.1 ‰). The relatively small wing area (0.053 m2) of COMUs compared to TBMUs (0.067 m2) may facilitate their increased agility while foraging and allow them to capture more mobile prey such as larger fishes that inhabit deeper depths. These differences in food resource use may lead to the differential responses of the two murre species to marine environmental changes in the Bering Sea.

  1. Fine-scale patterns of vegetation assembly in the monitoring of changes in coastal sand-dune landscapes

    Directory of Open Access Journals (Sweden)

    J. Honrado

    2010-02-01

    Full Text Available Understanding dune ecosystem responses to multi-scale environmental changes can provide the framework for reliable forecasts and cost-efficient protocols for detecting shifts in prevailing coastal dynamics. Based on the hypothesis that stress and disturbance interact as primary community controls in coastal dunes, we studied the fine-scale floristic assembly of foredune vegetation, in its relation to topography, along regional and local environmental gradients in the 200 km long coastline of northern Portugal, encompassing a major biogeographic transition in western Europe. Thirty topographic profiles perpendicular to the shoreline were recorded at ten sites along the regional climate gradient, and vegetation was sampled by recording the frequency of plant species along those profiles. Quantitative topographic attributes of vegetated dune profiles (e.g. length or height exhibited wide variations relatable to differences in prevailing coastal dynamics. Metrics of taxonomic diversity (e.g. total species richness and its additive beta component and of the functional composition of vegetation were highly correlated to attributes of dune topography. Under transgressive dynamics, vegetation profiles have fewer species, increased dominance, lower turnover rates, and lower total vegetation cover. These changes may drive a decrease in structural and functional diversity, with important consequences for resistance, resilience and other ecosystem properties. Moreover, differences in both vegetation assembly (in meta-stable dunes and response to increased disturbance (in eroding dunes between distinct biogeographic contexts highlight a possible decline in facilitation efficiency under extreme physical stress (i.e. under Mediterranean climate and support the significance of functional approaches in the study of local ecosystem responses to disturbance along regional gradients. Our results strongly suggest that assessing fine-scale community assembly can

  2. Seasonal variation in coastal marine habitat use by the European shag: Insights from fine scale habitat selection modeling and diet

    Science.gov (United States)

    Michelot, Candice; Pinaud, David; Fortin, Matthieu; Maes, Philippe; Callard, Benjamin; Leicher, Marine; Barbraud, Christophe

    2017-07-01

    Studies of habitat selection by higher trophic level species are necessary for using top predator species as indicators of ecosystem functioning. However, contrary to terrestrial ecosystems, few habitat selection studies have been conducted at a fine scale for coastal marine top predator species, and fewer have coupled diet data with habitat selection modeling to highlight a link between prey selection and habitat use. The aim of this study was to characterize spatially and oceanographically, at a fine scale, the habitats used by the European Shag Phalacrocorax aristotelis in the Special Protection Area (SPA) of Houat-Hœdic in the Mor Braz Bay during its foraging activity. Habitat selection models were built using in situ observation data of foraging shags (transect sampling) and spatially explicit environmental data to characterize marine benthic habitats. Observations were first adjusted for detectability biases and shag abundance was subsequently spatialized. The influence of habitat variables on shag abundance was tested using Generalized Linear Models (GLMs). Diet data were finally confronted to habitat selection models. Results showed that European shags breeding in the Mor Braz Bay changed foraging habitats according to the season and to the different environmental and energetic constraints. The proportion of the main preys also varied seasonally. Rocky and coarse sand habitats were clearly preferred compared to fine or muddy sand habitats. Shags appeared to be more selective in their foraging habitats during the breeding period and the rearing of chicks, using essentially rocky areas close to the colony and consuming preferentially fish from the Labridae family and three other fish families in lower proportions. During the post-breeding period shags used a broader range of habitats and mainly consumed Gadidae. Thus, European shags seem to adjust their feeding strategy to minimize energetic costs, to avoid intra-specific competition and to maximize access

  3. GeneRecon Users' Manual — A coalescent based tool for fine-scale association mapping

    DEFF Research Database (Denmark)

    Mailund, T

    2006-01-01

    GeneRecon is a software package for linkage disequilibrium mapping using coalescent theory. It is based on Bayesian Markov-chain Monte Carlo (MCMC) method for fine-scale linkage-disequilibrium gene mapping using high-density marker maps. GeneRecon explicitly models the genealogy of a sample...

  4. Adaptive integration of local region information to detect fine-scale brain activity patterns

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    With the rapid development of functional magnetic resonance imaging (fMRI) technology, the spatial resolution of fMRI data is continuously growing. This pro- vides us the possibility to detect the fine-scale patterns of brain activities. The es- tablished univariate and multivariate methods to analyze fMRI data mostly focus on detecting the activation blobs without considering the distributed fine-scale pat- terns within the blobs. To improve the sensitivity of the activation detection, in this paper, multivariate statistical method and univariate statistical method are com- bined to discover the fine-grained activity patterns. For one voxel in the brain, a local homogenous region is constructed. Then, time courses from the local ho- mogenous region are integrated with multivariate statistical method. Univariate statistical method is finally used to construct the interests of statistic for that voxel. The approach has explicitly taken into account the structures of both activity pat- terns and existing noise of local brain regions. Therefore, it could highlight the fine-scale activity patterns of the local regions. Experiments with simulated and real fMRI data demonstrate that the proposed method dramatically increases the sensitivity of detection of fine-scale brain activity patterns which contain the subtle information about experimental conditions.

  5. Fine-Scale Mapping of the FGFR2 Breast Cancer Risk Locus

    DEFF Research Database (Denmark)

    Meyer, Kerstin B; O'Reilly, Martin; Michailidou, Kyriaki

    2013-01-01

    The 10q26 locus in the second intron of FGFR2 is the locus most strongly associated with estrogen-receptor-positive breast cancer in genome-wide association studies. We conducted fine-scale mapping in case-control studies genotyped with a custom chip (iCOGS), comprising 41 studies (n = 89,050) of...

  6. Fine scale variations of surface water chemistry in an ephemeral to perennial drainage network

    Science.gov (United States)

    Margaret A. Zimmer; Scott W. Bailey; Kevin J. McGuire; Thomas D. Bullen

    2013-01-01

    Although temporal variation in headwater stream chemistry has long been used to document baseline conditions and response to environmental drivers, less attention is paid to fine scale spatial variations that could yield clues to processes controlling stream water sources. We documented spatial and temporal variation in water composition in a headwater catchment (41 ha...

  7. Fine Scale Modeling and Forecasts of Upper Atmospheric Turbulence for Operational Use

    Science.gov (United States)

    2014-11-30

    nonequilibrium layer dynamics at fine scales, Phys. Scr . 89 (22pp) 098001 (2014). Observation and simulation of wave breaking in the southern hemispheric...physics, turbulent mixing , rotation, ... Qm = /^d^m^ ^m = ^v’^c’^/’ -• ^rc the couplcd mixing ratios of water vapor, cloud, ice, etc. e^=6[\\^{R^lR

  8. Adaptive intesration of local resion information to detect fine-scale brain activity patterns

    Institute of Scientific and Technical Information of China (English)

    ZHEN ZongLei; TIAN Jie; ZHANG Hui

    2008-01-01

    With the rapid development of functional magnetic resonance imaging (fMRI) technology, the spatial resolution of fMRI data is continuously growing. This pro-vides us the possibility to detect the fine-scale patterns of brain activities. The es-tablished univariate and multivariate methods to analyze fMRI data mostly focus on detecting the activation blobs without considering the distributed fine-scale pat-terns within the blobs. To improve the sensitivity of the activation detection, in this paper, multivariate statistical method and univariate statistical method are com-bined to discover the fine-grained activity patterns. For one voxel in the brain, a local homogenous region is constructed. Then, time courses from the local ho-mogenous region are integrated with multivariate statistical method. Univariate statistical method is finally used to construct the interests of statistic for that voxel. The approach has explicitly taken into account the structures of both activity pat-terns and existing noise of local brain regions. Therefore, it could highlight the fine-scale activity patterns of the local regions. Experiments with simulated and real fMRI data demonstrate that the proposed method dramatically increases the sensitivity of detection of fine-scale brain activity patterns which contain the subtle information about experimental conditions.

  9. Fine-scale spatial distribution of plants and resources on a sandy soil in the Sahel

    NARCIS (Netherlands)

    Rietkerk, M; Ouedraogo, T; Kumar, L; Sanou, S; van Langevelde, F; Kiema, A; van de Koppel, J; van Andel, J; Hearne, J; Skidmore, AK; de Ridder, N; Stroosnijder, L; Prins, HHT

    We studied fine-scale spatial plant distribution in relation to the spatial distribution of erodible soil particles, organic matter, nutrients and soil water on a sandy to sandy loam soil in the Sahel. We hypothesized that the distribution of annual plants would be highly spatially autocorrelated

  10. Fine-scale spatial distribution of plants and resources on a sandy soil in the Sahel

    NARCIS (Netherlands)

    Rietkerk, M.G.; Ouedraogo, T.; Kumar, L.; Sanou, S.; Langevelde, F. van; Kiema, A.; Koppel, J. van de; Andel, J. van; Hearne, J.; Skidmore, A.K.; Ridder, N. de; Stroosnijder, L.; Prins, H.H.T.

    2002-01-01

    We studied fine-scale spatial plant distribution in relation to the spatial distribution of erodible soil particles, organic matter, nutrients and soil water on a sandy to sandy loam soil in the Sahel. We hypothesized that the distribution of annual plants would be highly spatially autocorrelated

  11. GeneRecon—A coalescent based tool for fine-scale association mapping

    DEFF Research Database (Denmark)

    Mailund, Thomas; Schierup, Mikkel Heide; Pedersen, Christian Nørgaard Storm

    2006-01-01

    GeneRecon is a tool for fine-scale association mapping using a coalescence model. GeneRecon takes as input case-control data from phased or unphased SNP and micro-satellite genotypes. The posterior distribution of disease locus position is obtained by Metropolis Hastings sampling in the state space...

  12. Mixing Eucalyptus and Acacia trees leads to fine root over-yielding and vertical segregation between species.

    Science.gov (United States)

    Laclau, Jean-Paul; Nouvellon, Yann; Reine, Caroline; Gonçalves, José Leonardo de Moraes; Krushe, Alex Vladimir; Jourdan, Christophe; le Maire, Guerric; Bouillet, Jean-Pierre

    2013-07-01

    The consequences of diversity on belowground processes are still poorly known in tropical forests. The distributions of very fine roots (diameter Acacia mangium (100A) stands and a mixture with the same stocking density and 50% of each species (50A:50E). The total fine root (FR) biomass down to a depth of 2 m was about 27% higher in 50A:50E than in 100A and 100E. Fine root over-yielding in 50A:50E resulted from a 72 % rise in E. grandis fine root biomass per tree relative to 100E, whereas A. mangium FR biomass per tree was 17% lower than in 100A. Mixing A. mangium with E. grandis trees led to a drop in A. mangium FR biomass in the upper 50 cm of soil relative to 100A, partially balanced by a rise in deep soil layers. Our results highlight similarities in the effects of directional resources on leaf and FR distributions in the mixture, with A. mangium leaves below the E. grandis canopy and a low density of A. mangium fine roots in the resource-rich soil layers relative to monospecific stands. The vertical segregation of resource-absorbing organs did not lead to niche complementarity expected to increase the total biomass production.

  13. Genome-wide fine-scale recombination rate variation in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Andrew H Chan

    Full Text Available Estimating fine-scale recombination maps of Drosophila from population genomic data is a challenging problem, in particular because of the high background recombination rate. In this paper, a new computational method is developed to address this challenge. Through an extensive simulation study, it is demonstrated that the method allows more accurate inference, and exhibits greater robustness to the effects of natural selection and noise, compared to a well-used previous method developed for studying fine-scale recombination rate variation in the human genome. As an application, a genome-wide analysis of genetic variation data is performed for two Drosophila melanogaster populations, one from North America (Raleigh, USA and the other from Africa (Gikongoro, Rwanda. It is shown that fine-scale recombination rate variation is widespread throughout the D. melanogaster genome, across all chromosomes and in both populations. At the fine-scale, a conservative, systematic search for evidence of recombination hotspots suggests the existence of a handful of putative hotspots each with at least a tenfold increase in intensity over the background rate. A wavelet analysis is carried out to compare the estimated recombination maps in the two populations and to quantify the extent to which recombination rates are conserved. In general, similarity is observed at very broad scales, but substantial differences are seen at fine scales. The average recombination rate of the X chromosome appears to be higher than that of the autosomes in both populations, and this pattern is much more pronounced in the African population than the North American population. The correlation between various genomic features-including recombination rates, diversity, divergence, GC content, gene content, and sequence quality-is examined using the wavelet analysis, and it is shown that the most notable difference between D. melanogaster and humans is in the correlation between

  14. Assessment of fine-scale parameterizations of turbulent dissipation rates in the Southern Ocean

    Science.gov (United States)

    Takahashi, A.; Hibiya, T.

    2016-12-01

    To sustain the global overturning circulation, more mixing is required in the ocean than has been observed. The most likely candidates for this missing mixing are breaking of wind-induced near-inertial waves and bottom-generated internal lee waves in the sparsely observed Southern Ocean. Nevertheless, there is a paucity of direct microstructure measurements in the Southern Ocean where energy dissipation rates have been estimated mostly using fine-scale parameterizations. In this study, we assess the validity of the existing fine-scale parameterizations in the Antarctic Circumpolar Current (ACC) region using the data obtained from simultaneous full-depth measurements of micro-scale turbulence and fine-scale shear/strain carried out south of Australia during January 17 to February 2, 2016. Although the fine-scale shear/strain ratio (Rω) is close to the Garrett-Munk (GM) value at the station north of Subtropical Front, the values of Rω at the stations south of Subantarctic Front well exceed the GM value, suggesting that the local internal wave spectra are significantly biased to lower frequencies. We find that not all of the observed energy dissipation rates at these locations are well predicted using Gregg-Henyey-Polzin (GHP; Gregg et al., 2003) and Ijichi-Hibiya (IH; Ijichi and Hibiya, 2015) parameterizations, both of which take into account the spectral distortion in terms of Rω; energy dissipation rates at some locations are obviously overestimated by GHP and IH, although only the strain-based Wijesekera (Wijesekera et al., 1993) parameterization yields fairly good predictions. One possible explanation for this result is that a significant portion of the observed shear variance at these locations might be attributed to kinetic-energy-dominant small-scale eddies associated with the ACC, so that fine-scale strain rather than Rω becomes a more appropriate parameter to characterize the actual internal wave field.

  15. Fine scale population genetic structure of Varroa destructor, an ectoparasitic mite of the honey bee (Apis mellifera)

    Science.gov (United States)

    Dynes, Travis L.; De Roode, Jacobus C.; Lyons, Justine I.; Berry, Jennifer A.; Delaplane, Keith S.; Brosi, Berry J.

    2016-01-01

    Varroa destructor is an obligate ectoparasitic mite and the most important biotic threat currently facing honey bees (Apis mellifera). We used neutral microsatellites to analyze previously unreported fine scale population structure of V. destructor, a species characterized by extreme lack of genetic diversity owing to multiple bottleneck events, haplodiploidy, and primarily brother-sister matings. Our results surprisingly indicate that detectable hierarchical genetic variation exists between apiaries, between colonies within an apiary, and even within colonies. This finding of within-colony parasite diversity provides empirical evidence that the spread of V. destructor is not accomplished solely by vertical transmission but that horizontal transmission (natural or human-mediated) must occur regularly. PMID:27812229

  16. Fine-scale genetic structure and cryptic associations reveal evidence of kin-based sociality in the African forest elephant.

    Science.gov (United States)

    Schuttler, Stephanie G; Philbrick, Jessica A; Jeffery, Kathryn J; Eggert, Lori S

    2014-01-01

    Spatial patterns of relatedness within animal populations are important in the evolution of mating and social systems, and have the potential to reveal information on species that are difficult to observe in the wild. This study examines the fine-scale genetic structure and connectivity of groups within African forest elephants, Loxodonta cyclotis, which are often difficult to observe due to forest habitat. We tested the hypothesis that genetic similarity will decline with increasing geographic distance, as we expect kin to be in closer proximity, using spatial autocorrelation analyses and Tau K(r) tests. Associations between individuals were investigated through a non-invasive genetic capture-recapture approach using network models, and were predicted to be more extensive than the small groups found in observational studies, similar to fission-fusion sociality found in African savanna (Loxodonta africana) and Asian (Elephas maximus) species. Dung samples were collected in Lopé National Park, Gabon in 2008 and 2010 and genotyped at 10 microsatellite loci, genetically sexed, and sequenced at the mitochondrial DNA control region. We conducted analyses on samples collected at three different temporal scales: a day, within six-day sampling sessions, and within each year. Spatial autocorrelation and Tau K(r) tests revealed genetic structure, but results were weak and inconsistent between sampling sessions. Positive spatial autocorrelation was found in distance classes of 0-5 km, and was strongest for the single day session. Despite weak genetic structure, individuals within groups were significantly more related to each other than to individuals between groups. Social networks revealed some components to have large, extensive groups of up to 22 individuals, and most groups were composed of individuals of the same matriline. Although fine-scale population genetic structure was weak, forest elephants are typically found in groups consisting of kin and based on matrilines

  17. Fine-scale genetic structure and cryptic associations reveal evidence of kin-based sociality in the African forest elephant.

    Directory of Open Access Journals (Sweden)

    Stephanie G Schuttler

    Full Text Available Spatial patterns of relatedness within animal populations are important in the evolution of mating and social systems, and have the potential to reveal information on species that are difficult to observe in the wild. This study examines the fine-scale genetic structure and connectivity of groups within African forest elephants, Loxodonta cyclotis, which are often difficult to observe due to forest habitat. We tested the hypothesis that genetic similarity will decline with increasing geographic distance, as we expect kin to be in closer proximity, using spatial autocorrelation analyses and Tau K(r tests. Associations between individuals were investigated through a non-invasive genetic capture-recapture approach using network models, and were predicted to be more extensive than the small groups found in observational studies, similar to fission-fusion sociality found in African savanna (Loxodonta africana and Asian (Elephas maximus species. Dung samples were collected in Lopé National Park, Gabon in 2008 and 2010 and genotyped at 10 microsatellite loci, genetically sexed, and sequenced at the mitochondrial DNA control region. We conducted analyses on samples collected at three different temporal scales: a day, within six-day sampling sessions, and within each year. Spatial autocorrelation and Tau K(r tests revealed genetic structure, but results were weak and inconsistent between sampling sessions. Positive spatial autocorrelation was found in distance classes of 0-5 km, and was strongest for the single day session. Despite weak genetic structure, individuals within groups were significantly more related to each other than to individuals between groups. Social networks revealed some components to have large, extensive groups of up to 22 individuals, and most groups were composed of individuals of the same matriline. Although fine-scale population genetic structure was weak, forest elephants are typically found in groups consisting of kin and

  18. How Elephant Seals (Mirounga leonina) Adjust Their Fine Scale Horizontal Movement and Diving Behaviour in Relation to Prey Encounter Rate

    Science.gov (United States)

    Jouma’a, Joffrey; Picard, Baptiste; Guinet, Christophe

    2016-01-01

    Understanding the diving behaviour of diving predators in relation to concomitant prey distribution could have major practical applications in conservation biology by allowing the assessment of how changes in fine scale prey distribution impact foraging efficiency and ultimately population dynamics. The southern elephant seal (Mirounga leonina, hereafter SES), the largest phocid, is a major predator of the southern ocean feeding on myctophids and cephalopods. Because of its large size it can carry bio-loggers with minimal disturbance. Moreover, it has great diving abilities and a wide foraging habitat. Thus, the SES is a well suited model species to study predator diving behaviour and the distribution of ecologically important prey species in the Southern Ocean. In this study, we examined how SESs adjust their diving behaviour and horizontal movements in response to fine scale prey encounter densities using high resolution accelerometers, magnetometers, pressure sensors and GPS loggers. When high prey encounter rates were encountered, animals responded by (1) diving and returning to the surface with steeper angles, reducing the duration of transit dive phases (thus improving dive efficiency), and (2) exhibiting more horizontally and vertically sinuous bottom phases. In these cases, the distance travelled horizontally at the surface was reduced. This behaviour is likely to counteract horizontal displacement from water currents, as they try to remain within favourable prey patches. The prey encounter rate at the bottom of dives decreased with increasing diving depth, suggesting a combined effect of decreased accessibility and prey density with increasing depth. Prey encounter rate also decreased when the bottom phases of dives were spread across larger vertical extents of the water column. This result suggests that the vertical aggregation of prey can regulate prey density, and as a consequence impact the foraging success of SESs. To our knowledge, this is one of

  19. Novel Bio-Logging Tool for Studying Fine-Scale Behaviors of Marine Turtles in Response to Sound

    Directory of Open Access Journals (Sweden)

    Reny B. Tyson

    2017-07-01

    Full Text Available Increases in the spatial scale and intensity of activities that produce marine anthropogenic sound highlight the importance of understanding the impacts and effects of sound on threatened species such as marine turtles. Marine turtles detect and behaviorally respond to low-frequency sounds, however few studies have directly examined their behavioral responses to specific types or intensities of anthropogenic or natural sounds. Recent advances in the development of bio-logging tools, which combine acoustic and fine-scale movement measurements, have allowed for evaluations of animal responses to sound. Here, we describe these tools and present a case study demonstrating the potential application of a newly developed technology (ROTAG, Loggerhead Instruments, Inc. to examine behavioral responses of freely swimming marine turtles to sound. The ROTAG incorporates a three-axis accelerometer, gyroscope, and magnetometer to record the turtle's pitch, roll, and heading; a pressure sensor to record turtle depth; a hydrophone to record the turtle's received underwater acoustic sound field; a temperature gauge; and two VHF radio telemetry transmitters and antennas for tag and turtle tracking. Tags can be programmed to automatically release via a timed corrodible link several hours or days after deployment. We describe an example of the data collected with these tags and present a case study of a successful ROTAG deployment on a juvenile green turtle (Chelonia mydas in the Paranaguá Estuary Complex, Brazil. The tag was deployed for 221 min, during which several vessels passed closely (<2 km by the turtle. The concurrent movement and acoustic data collected by the ROTAG were examined during these times to determine if the turtle responded to these anthropogenic sound sources. While fine-scale behavioral responses were not apparent (second-by-second, the turtle did appear to perform dives during which it remained still on or near the sea floor during several

  20. Beyond habitat requirements: individual fine-scale site fidelity in a colony of the Galapagos sea lion (Zalophus wollebaeki) creates conditions for social structuring.

    Science.gov (United States)

    Wolf, Jochen B W; Trillmich, Fritz

    2007-06-01

    Site fidelity has been widely discussed, but rarely been related explicitly to a species' social context. This is surprising, as fine-scale site fidelity constitutes an important structural component in animal societies by setting limits to an individual's social interaction space. The study of fine-scale site fidelity is complicated by the fact that it is inextricably linked to patterns of habitat use. We here document fine-scale site fidelity in the Galapagos sea lion (Zalophus wollebaeki) striving to disentangle these two aspects of spatial behaviour. Regardless of sex and age, all individuals used small, cohesive home ranges, which were stable in size across the reproductive and non-reproductive season. Home ranges showed a large individual component and did not primarily reflect age- or sex-specific habitat requirements. Site specificity could be illustrated up to a resolution of several metres. Long-term site fidelity was indicated by home range persistence over 3 years and the degree of site fidelity was unaffected by habitat, but showed seasonal differences: it was lower between reproductive and non-reproductive periods than between reproductive seasons. We further examined static and social interaction within mother-offspring pairs, which constitute a central social unit in most mammalian societies. Regardless of the occupied habitat type, adult females with offspring had smaller home range sizes than non-breeding females, demonstrating the importance of spatial predictability for mother-offspring pairs that recurrently have to reunite after females' foraging sojourns. While social interaction with the mother dropped to naught in both sexes after weaning, analysis of static interaction suggested female-biased home range inheritance. Dispersal decisions were apparently not based on habitat quality, but determined by the offspring's sex. We discuss the implication of observed fine-scale site fidelity patterns on habitat use, dispersal decisions and social

  1. Fine scale heterogeneity in the Earth's upper mantle - observation and interpretation

    DEFF Research Database (Denmark)

    Thybo, Hans

    2014-01-01

    can be correlated to main plate tectonic features, such as oceanic spreading centres, continental rift zones and subducting slabs. Much seismological mantle research is now concentrated on imaging fine scale heterogeneity, which may be detected and imaged with high-resolution seismic data with dense......High resolution seismic data has over the last decade provided significant evidence for pronounced fine scale heterogeneity in the Earth’s mantle at an unprecedented detail. Seismic tomography developed tremendously during the last 20-30 years. The results show overall structure in the mantle which...... station spacing and at high frequency, e.g. from the Russian Peaceful Nuclear Explosion (PNE) data set and array recordings of waves from natural seismic sources. Mantle body waves indicate pronounced heterogeneity at three depth levels whereas other depth intervals appear transparent, at least...

  2. Intermittency at Fine Scales and Complex Singularities of Turbulent Couette Flow

    CERN Document Server

    Souza, Andre

    2015-01-01

    Fine scales of turbulent velocity fields, beyond the inertial range and well into the dissipative range, are highly intermittent. It has been hypothesized that complex plane singularities are the principal mechanism behind fine scale intermittency. In this article, we view the velocity field of a turbulent flow as an analytic function of time. Although the function is only available for real values of time, we present a numerical technique to analytically continue the function to complex values of time, and with sufficient fidelity to locate and visualize the singularity closest to the real axis. Using this technique, we demonstrate a robust connection between temporal intermittency and the location of singularities in the complex plane.

  3. Quad-plane stereoscopic PIV for fine-scale structure measurements in turbulence

    Science.gov (United States)

    Naka, Y.; Tomita, K.; Shimura, M.; Fukushima, N.; Tanahashi, M.; Miyauchi, T.

    2016-05-01

    The fine-scale structure in turbulence is investigated by quad-plane stereoscopic particle image velocimetry (QPSPIV). The quad-plane consists of two each of different polarizations and wavelengths, and it provides three velocity components at four independent parallel planes. Measurements have been undertaken in the developed region of a turbulent round jet with a spatial resolution sufficient to capture the small-scale structures. The advantage of the QPSPIV is presented in terms of the spectral response in the evaluation of the out-of-plane velocity gradient. The full velocity gradient tensor is computed with a fourth-order finite difference scheme in the out-of-plane direction as well as the in-plane directions. The turbulence quantities, such as the vorticity components, the energy dissipation rate and the second and third invariants of the velocity gradient tensor, are computed according to their faithful definitions. The coherent fine-scale eddies are extracted from the present QPSPIV data. The probability density functions of the diameter and the maximum azimuthal velocity of the extracted eddies exhibit their peak at approximately 8η and 1.5u_k, respectively, where η and u_k are the Kolmogorov length and velocity. These values agree well with the data in the literature. The phase-averaged distributions of turbulence quantities around the coherent fine-scale eddy indicate an apparent elliptic feature around the axis. Furthermore, the state of the strain rate exerting the eddy is quantified from the phase-averaged distributions of eigenvalues of the strain rate tensor and the alignment of the corresponding eigenvectors against the axis. The present study gives a solid experimental support of the coherent fine-scale structures in turbulence, and the technique can be applied to various flow fields and to the higher Reynolds number condition.

  4. GeneRecon—A coalescent based tool for fine-scale association mapping

    DEFF Research Database (Denmark)

    Mailund, Thomas; Schierup, Mikkel Heide; Pedersen, Christian Nørgaard Storm

    2006-01-01

    GeneRecon is a tool for fine-scale association mapping using a coalescence model. GeneRecon takes as input case-control data from phased or unphased SNP and micro-satellite genotypes. The posterior distribution of disease locus position is obtained by Metropolis Hastings sampling in the state space...... of genealogies. Input format, search strategy, and the sampled statistics can be configured through the Guile Scheme programming language embedded in GeneRecon, making GeneRecon highly configurable....

  5. Higher fine-scale genetic structure in peripheral than in core populations of a long-lived and mixed-mating conifer - eastern white cedar (Thuja occidentalis L.

    Directory of Open Access Journals (Sweden)

    Pandey Madhav

    2012-04-01

    Full Text Available Abstract Background Fine-scale or spatial genetic structure (SGS is one of the key genetic characteristics of plant populations. Several evolutionary and ecological processes and population characteristics influence the level of SGS within plant populations. Higher fine-scale genetic structure may be expected in peripheral than core populations of long-lived forest trees, owing to the differences in the magnitude of operating evolutionary and ecological forces such as gene flow, genetic drift, effective population size and founder effects. We addressed this question using eastern white cedar (Thuja occidentalis as a model species for declining to endangered long-lived tree species with mixed-mating system. Results We determined the SGS in two core and two peripheral populations of eastern white cedar from its Maritime Canadian eastern range using six nuclear microsatellite DNA markers. Significant SGS ranging from 15 m to 75 m distance classes was observed in the four studied populations. An analysis of combined four populations revealed significant positive SGS up to the 45 m distance class. The mean positive significant SGS observed in the peripheral populations was up to six times (up to 90 m of that observed in the core populations (15 m. Spatial autocorrelation coefficients and correlograms of single and sub-sets of populations were statistically significant. The extent of within-population SGS was significantly negatively correlated with all genetic diversity parameters. Significant heterogeneity of within-population SGS was observed for 0-15 m and 61-90 m between core and peripheral populations. Average Sp, and gene flow distances were higher in peripheral (Sp = 0.023, σg = 135 m than in core (Sp = 0.014, σg = 109 m populations. However, the mean neighborhood size was higher in the core (Nb = 82 than in the peripheral (Nb = 48 populations. Conclusion Eastern white cedar populations have significant fine-scale genetic structure at short

  6. Fine-scale Structures of Flux Ropes Tracked by Erupting Material

    CERN Document Server

    Li, Ting

    2013-01-01

    We present the Solar Dynamics Observatory observations of two flux ropes respectively tracked out by material from a surge and a failed filament eruption on 2012 July 29 and August 04. For the first event, the interaction between the erupting surge and a loop-shaped filament in the east seems to "peel off" the filament and add bright mass into the flux rope body. The second event is associated with a C-class flare that occurs several minutes before the filament activation. The two flux ropes are respectively composed of 85$\\pm$12 and 102$\\pm$15 fine-scale structures, with an average width of about 1$\\arcsec$.6. Our observations show that two extreme ends of the flux rope are rooted in the opposite polarity fields and each end is composed of multiple footpoints (FPs) of the fine-scale structures. The FPs of the fine-scale structures are located at network magnetic fields, with magnetic fluxes from 5.6$\\times10^{18}$ Mx to 8.6$\\times10^{19}$ Mx. Moreover, almost half of the FPs show converging motion of smaller...

  7. Parallelization of fine-scale computation in Agile Multiscale Modelling Methodology

    Science.gov (United States)

    Macioł, Piotr; Michalik, Kazimierz

    2016-10-01

    Nowadays, multiscale modelling of material behavior is an extensively developed area. An important obstacle against its wide application is high computational demands. Among others, the parallelization of multiscale computations is a promising solution. Heterogeneous multiscale models are good candidates for parallelization, since communication between sub-models is limited. In this paper, the possibility of parallelization of multiscale models based on Agile Multiscale Methodology framework is discussed. A sequential, FEM based macroscopic model has been combined with concurrently computed fine-scale models, employing a MatCalc thermodynamic simulator. The main issues, being investigated in this work are: (i) the speed-up of multiscale models with special focus on fine-scale computations and (ii) on decreasing the quality of computations enforced by parallel execution. Speed-up has been evaluated on the basis of Amdahl's law equations. The problem of `delay error', rising from the parallel execution of fine scale sub-models, controlled by the sequential macroscopic sub-model is discussed. Some technical aspects of combining third-party commercial modelling software with an in-house multiscale framework and a MPI library are also discussed.

  8. Temporal changes in vegetation of a virgin beech woodland remnant: stand-scale stability with intensive fine-scale dynamics governed by stand dynamic events

    Directory of Open Access Journals (Sweden)

    Tibor Standovár

    2017-03-01

    Full Text Available The aim of this resurvey study is to check if herbaceous vegetation on the forest floor exhibits overall stability at the stand-scale in spite of intensive dynamics at the scale of individual plots and stand dynamic events (driven by natural fine scale canopy gap dynamics. In 1996, we sampled a 1.5 ha patch using 0.25 m² plots placed along a 5 m × 5 m grid in the best remnant of central European montane beech woods in Hungary. All species in the herbaceous layer and their cover estimates were recorded. Five patches representing different stand developmental situations (SDS were selected for resurvey. In 2013, 306 plots were resurveyed by using blocks of four 0.25 m² plots to test the effects of imperfect relocation. We found very intensive fine-scale dynamics in the herbaceous layer with high species turnover and sharp changes in ground layer cover at the local-scale (< 1 m2. A decrease in species richness and herbaceous layer cover, as well as high species turnover, characterized the closing gaps. Colonization events and increasing species richness and herbaceous layer cover prevailed in the two newly created gaps. A pronounced decrease in the total cover, but low species turnover and survival of the majority of the closed forest specialists was detected by the resurvey at the stand-scale. The test aiming at assessing the effect of relocation showed a higher time effect than the effect of imprecise relocation. The very intensive fine-scale dynamics of the studied beech forest are profoundly determined by natural stand dynamics. Extinction and colonisation episodes even out at the stand-scale, implying an overall compositional stability of the herbaceous vegetation at the given spatial and temporal scale. We argue that fine-scale gap dynamics, driven by natural processes or applied as a management method, can warrant the survival of many closed forest specialist species in the long-run. Nomenclature: Flora Europaea (Tutin et al. 2010 for

  9. Nutrient limitation and physiology mediate the fine-scale (de)coupling of biogeochemical cycles.

    Science.gov (United States)

    Appling, Alison P; Heffernan, James B

    2014-09-01

    Nutrients in the environment are coupled over broad timescales (days to seasons) when organisms add or withdraw multiple nutrients simultaneously and in ratios that are roughly constant. But at finer timescales (seconds to days), nutrients become decoupled if physiological traits such as nutrient storage limits, circadian rhythms, or enzyme kinetics cause one nutrient to be processed faster than another. To explore the interactions among these coupling and decoupling mechanisms, we introduce a model in which organisms process resources via uptake, excretion, growth, respiration, and mortality according to adjustable trait parameters. The model predicts that uptake can couple the input of one nutrient to the export of another in a ratio reflecting biological demand stoichiometry, but coupling occurs only when the input nutrient is limiting. Temporal nutrient coupling may, therefore, be a useful indicator of ecosystem limitation status. Fine-scale patterns of nutrient coupling are further modulated by, and potentially diagnostic of, physiological traits governing growth, uptake, and internal nutrient storage. Together, limitation status and physiological traits create a complex and informative relationship between nutrient inputs and exports. Understanding the mechanisms behind that relationship could enrich interpretations of fine-scale time-series data such as those now emerging from in situ solute sensors.

  10. Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir

    Directory of Open Access Journals (Sweden)

    Jean-Baptiste Burnet

    2015-09-01

    Full Text Available Background: The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Methods: Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Results: Parasites displayed heterogeneous distribution patterns, as reflected by significant (oocyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. Conclusion: This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

  11. Fine-Scale Structure of the Moho From Receiver Functions: Effects of a Deforming Crust

    Science.gov (United States)

    Zandt, G.; Gilbert, H.; Ozacar, A.; Owens, T. J.

    2004-12-01

    Andrija Mohorovicic, a Croatian seismologist, is credited with the first estimation in 1906 of crustal thickness using the critically refracted phase Pn. The crust-mantle boundary has become commonly known as the Moho and its depth, structure, formation, and evolution remains an important research topic in seismology, petrology, and tectonics. Other seismic phases sensitive to Moho depth and structure are the converted phases Ps and Sp, and the associated 2p1s and 1p2s reverberation phases that are isolated in receiver function waveforms. With sufficient station coverage, multiple receiver functions can be migrated and stacked into cross-sections of the crust. Crustal cross-sections from tectonically active regions reveal dramatic variations in amplitude and frequency content of Moho phases that we associate with fine-scale structure, and possibly anisotropy at the crust-mantle boundary. The Moho amplitude or "brightness" is a measure of the crust-mantle impedance contrast, thickness and structure within the crust-mantle boundary, and effects of scattering from 3D structure. Processes directly related to these Moho structures include crustal thickening, crustal extension, crustal flow, delamination or convective removal, and eclogitization. Therefore, the fine-scale seismological structure of the Moho is an important constraint in regional tectonic reconstructions. Examples of receiver function crustal images and their tectonic implications from the western US, South American Andes, and the Tibetan plateau will be reviewed.

  12. Fine-scale estimations of bioclimatic change in the Valencia region, Spain

    Science.gov (United States)

    Miró, Juan Javier; Estrela, María José; Caselles, Vicente; Olcina-Cantos, Jorge

    2016-11-01

    Recent advances in statistical downscaling have allowed the reconstruction of temperatures for the complete 1948-2011 period in a spatial resolution of 90 m and without gaps for the Valencian Community (Spain) and bordering areas. It presently enables analyses in this region, which allows the determination of recent temperature changes at subregional and local scales. The present work focuses on obtaining the thermicity index according to Rivas-Martínez, a well-known indicator of different thermotypes associated with bioclimatic horizons. The change in this index, which has happened in the region between 1948 and 2011, was calculated by generating fine-scale maps of the potential extension of different thermotypes. The results show a greater regression for the thermotypes in a finicolous position, e.g. Orotemperate, Supratemperate and Supramediterranean horizons, which herein indicate greater potential vulnerability in climate change. In the absence of, and given the need for, such fine-scale information, this work should be useful for specialized researchers to spatially limit the potentially most vulnerable biotopes to climate change.

  13. Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir.

    Science.gov (United States)

    Burnet, Jean-Baptiste; Ogorzaly, Leslie; Penny, Christian; Cauchie, Henry-Michel

    2015-09-23

    The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Parasites displayed heterogeneous distribution patterns, as reflected by significant (oo)cyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir) for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

  14. Fine-scale population structure of blue whale wintering aggregations in the Gulf of California.

    Science.gov (United States)

    Costa-Urrutia, Paula; Sanvito, Simona; Victoria-Cota, Nelva; Enríquez-Paredes, Luis; Gendron, Diane

    2013-01-01

    Population differentiation in environments without well-defined geographical barriers represents a challenge for wildlife management. Based on a comprehensive database of individual sighting records (1988-2009) of blue whales from the winter/calving Gulf of California, we assessed the fine-scale genetic and spatial structure of the population using individual-based approaches. Skin samples of 187 individuals were analyzed for nine microsatellite loci. A single population with no divergence among years and months and no isolation by distance (Rxy = 0.1-0.001, p>0.05) were found. We ran two bayesian clustering methods using Structure and Geneland softwares in two different ways: 1) a general analysis including all individuals in which a single cluster was identified with both softwares; 2) a specific analysis of females only in which two main clusters (Loreto Bay and northern areas, and San Jose-La Paz Bay area) were revealed by Geneland program. This study provides information indicating that blue whales wintering in the Gulf of California are part of a single population unit and showed a fine-scale structure among females, possibly associated with their high site fidelity, particularly when attending calves. It is likely that the loss of genetic variation is minimized by male mediated gene flow, which may reduce the genetic drift effect. Opportunities for kin selection may also influence calf survival and, in consequence, have a positive impact on population demography in this small and endangered population.

  15. Fine-scale population structure of blue whale wintering aggregations in the Gulf of California.

    Directory of Open Access Journals (Sweden)

    Paula Costa-Urrutia

    Full Text Available Population differentiation in environments without well-defined geographical barriers represents a challenge for wildlife management. Based on a comprehensive database of individual sighting records (1988-2009 of blue whales from the winter/calving Gulf of California, we assessed the fine-scale genetic and spatial structure of the population using individual-based approaches. Skin samples of 187 individuals were analyzed for nine microsatellite loci. A single population with no divergence among years and months and no isolation by distance (Rxy = 0.1-0.001, p>0.05 were found. We ran two bayesian clustering methods using Structure and Geneland softwares in two different ways: 1 a general analysis including all individuals in which a single cluster was identified with both softwares; 2 a specific analysis of females only in which two main clusters (Loreto Bay and northern areas, and San Jose-La Paz Bay area were revealed by Geneland program. This study provides information indicating that blue whales wintering in the Gulf of California are part of a single population unit and showed a fine-scale structure among females, possibly associated with their high site fidelity, particularly when attending calves. It is likely that the loss of genetic variation is minimized by male mediated gene flow, which may reduce the genetic drift effect. Opportunities for kin selection may also influence calf survival and, in consequence, have a positive impact on population demography in this small and endangered population.

  16. Contrasting patterns of clonality and fine-scale genetic structure in two rare sedges with differing geographic distributions.

    Science.gov (United States)

    Binks, R M; Millar, M A; Byrne, M

    2015-09-01

    For plants with mixed reproductive capabilities, asexual reproduction is more frequent in rare species and is considered a strategy for persistence when sexual recruitment is limited. We investigate whether asexual reproduction contributes to the persistence of two co-occurring, rare sedges that both experience irregular seed set and if their differing geographic distributions have a role in the relative contribution of clonality. Genotypic richness was high (R=0.889±0.02) across the clustered populations of Lepidosperma sp. Mt Caudan and, where detected, clonal patches were small, both in ramet numbers (⩽3 ramets/genet) and physical size (1.3±0.1 m). In contrast, genotypic richness was lower in the isolated L. sp. Parker Range populations, albeit more variable (R=0.437±0.13), with genets as large as 17 ramets and up to 5.8 m in size. Aggregated clonal growth generated significant fine-scale genetic structure in both species but to a greater spatial extent and with additional genet-level structure in L. sp. Parker Range that is likely due to restricted seed dispersal. Despite both species being rare, asexual reproduction clearly has a more important role in the persistence of L. sp. Parker Range than L. sp. Mt Caudan. This is consistent with our prediction that limitations to sexual reproduction, via geographic isolation to effective gene exchange, can lead to greater contributions of asexual reproduction. These results demonstrate the role of population isolation in affecting the balance of alternate reproductive modes and the contextual nature of asexual reproduction in rare species.

  17. Resource selection models are useful in predicting fine-scale distributions of black-footed ferrets in prairie dog colonies

    Science.gov (United States)

    Eads, David A.; Jachowski, David S.; Biggins, Dean E.; Livieri, Travis M.; Matchett, Marc R.; Millspaugh, Joshua J.

    2012-01-01

    Wildlife-habitat relationships are often conceptualized as resource selection functions (RSFs)—models increasingly used to estimate species distributions and prioritize habitat conservation. We evaluated the predictive capabilities of 2 black-footed ferret (Mustela nigripes) RSFs developed on a 452-ha colony of black-tailed prairie dogs (Cynomys ludovicianus) in the Conata Basin, South Dakota. We used the RSFs to project the relative probability of occurrence of ferrets throughout an adjacent 227-ha colony. We evaluated performance of the RSFs using ferret space use data collected via postbreeding spotlight surveys June–October 2005–2006. In home ranges and core areas, ferrets selected the predicted "very high" and "high" occurrence categories of both RSFs. Count metrics also suggested selection of these categories; for each model in each year, approximately 81% of ferret locations occurred in areas of very high or high predicted occurrence. These results suggest usefulness of the RSFs in estimating the distribution of ferrets throughout a black-tailed prairie dog colony. The RSFs provide a fine-scale habitat assessment for ferrets that can be used to prioritize releases of ferrets and habitat restoration for prairie dogs and ferrets. A method to quickly inventory the distribution of prairie dog burrow openings would greatly facilitate application of the RSFs.

  18. Fine-scale habitat use of reintroduced black-footed ferrets on prairie dog colonies in New Mexico

    Science.gov (United States)

    Chipault, Jennifer G.; Biggins, Dean E.; Detling, James K.; Long, Dustin H.; Reich, Robin M.

    2012-01-01

    Black-footed ferrets (Mustela nigripes) are among the most endangered animals in North America. Reintroductions of captive-born ferrets onto prairie dog (Cynomys spp.) colonies are crucial to the conservation of the species. In September 2007, captive-born ferrets were released on a black-tailed prairie dog (Cynomys ludovicianus) colony at the Vermejo Park Ranch, New Mexico. Ferret kits experimentally released in areas of comparatively low and high prairie dog burrow densities were located via spotlight surveys. Some maturing ferret kits were subsequently translocated to areas of low and high burrow densities on nearby prairie dog colonies. For 2 months, fine-scale habitat use was quantified by mapping all burrow openings within a 30-m radius of each ferret location. Spatial statistics accounted for autocorrelation in the burrow densities in areas used by ferrets. It was hypothesized that ferrets would select areas of high burrow densities within colonies; however, burrow densities in areas used by ferrets were generally similar to the available burrow densities. Because ferrets used areas with burrow densities similar to densities available at the colony level and because of the potential energetic benefits for ferrets using areas with high burrow densities, releasing ferrets on colonies with high burrow densities might increase reintroduction success.

  19. Significant demographic and fine-scale genetic structure in expanding and senescing populations of the terrestrial orchid Cymbidium goeringii (Orchidaceae).

    Science.gov (United States)

    Chung, Mi Yoon; Nason, John D; Chung, Myong Gi

    2011-12-01

    Fine-scale genetic structure (FSGS) in plants is influenced by variation in spatial and temporal demographic processes. To determine how demographic structure and FSGS change with stages of population succession, we studied replicate expanding and senescing populations of the Asian terrestrial orchid Cymbidium goeringii. We used spatial autocorrelation methods (O-ring and kinship statistics) to quantify spatial demographic structure and FSGS in two expanding and two senescing populations, also measuring genetic diversity and inbreeding in each. All populations exhibited significant aggregation of individuals and FSGS at short spatial scales. In expanding populations, this finding was associated with high recruitment rates, suggesting restricted seed dispersal. In senescing populations, recruitment was minimal, suggesting alternative mechanisms of aggregation, perhaps including spatial associations with mycorrhizal fungi. All populations had significant evidence of genetic bottlenecks, and inbreeding levels were consistently high. Our results indicate that different successional stages can generate similar patterns of spatial demographic and genetic structure, but as a consequence of different processes. These results contrast with the only other study of senescence effects on population genetic structure in an herbaceous perennial, which found little to no FSGS in senescing populations. With the exception of populations subject to mass collection by orchid sellers, significant FSGS is characteristic of the 16 terrestrial orchid species examined to date. From a conservation perspective, this result suggests that inference of orchid population history will benefit from analyses of both FSGS and demographic structure in combination with other ecological field data.

  20. A face in the crowd: a non-invasive and cost effective photo-identification methodology to understand the fine scale movement of eastern water dragons.

    Directory of Open Access Journals (Sweden)

    Riana Zanarivero Gardiner

    Full Text Available Ectothermic vertebrates face many challenges of thermoregulation. Many species rely on behavioral thermoregulation and move within their landscape to maintain homeostasis. Understanding the fine-scale nature of this regulation through tracking techniques can provide a better understanding of the relationships between such species and their dynamic environments. The use of animal tracking and telemetry technology has allowed the extensive collection of such data which has enabled us to better understand the ways animals move within their landscape. However, such technologies do not come without certain costs: they are generally invasive, relatively expensive, can be too heavy for small sized animals and unreliable in certain habitats. This study provides a cost-effective and non-invasive method through photo-identification, to determine fine scale movements of individuals. With our methodology, we have been able to find that male eastern water dragons (Intellagama leuseurii have home ranges one and a half times larger than those of females. Furthermore, we found intraspecific differences in the size of home ranges depending on the time of the day. Lastly, we found that location mostly influenced females' home ranges, but not males and discuss why this may be so. Overall, we provide valuable information regarding the ecology of the eastern water dragon, but most importantly demonstrate that non-invasive photo-identification can be successfully applied to the study of reptiles.

  1. A face in the crowd: a non-invasive and cost effective photo-identification methodology to understand the fine scale movement of eastern water dragons.

    Science.gov (United States)

    Gardiner, Riana Zanarivero; Doran, Erik; Strickland, Kasha; Carpenter-Bundhoo, Luke; Frère, Celine

    2014-01-01

    Ectothermic vertebrates face many challenges of thermoregulation. Many species rely on behavioral thermoregulation and move within their landscape to maintain homeostasis. Understanding the fine-scale nature of this regulation through tracking techniques can provide a better understanding of the relationships between such species and their dynamic environments. The use of animal tracking and telemetry technology has allowed the extensive collection of such data which has enabled us to better understand the ways animals move within their landscape. However, such technologies do not come without certain costs: they are generally invasive, relatively expensive, can be too heavy for small sized animals and unreliable in certain habitats. This study provides a cost-effective and non-invasive method through photo-identification, to determine fine scale movements of individuals. With our methodology, we have been able to find that male eastern water dragons (Intellagama leuseurii) have home ranges one and a half times larger than those of females. Furthermore, we found intraspecific differences in the size of home ranges depending on the time of the day. Lastly, we found that location mostly influenced females' home ranges, but not males and discuss why this may be so. Overall, we provide valuable information regarding the ecology of the eastern water dragon, but most importantly demonstrate that non-invasive photo-identification can be successfully applied to the study of reptiles.

  2. Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta Forests.

    Directory of Open Access Journals (Sweden)

    Anne C S McIntosh

    Full Text Available Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs and multiple carbon-source substrate-induced respiration (MSIR of the forest floor microbial community environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis showed that two above-ground (mean tree diameter, litter cover and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs properties were associated with variation in understory plant community composition. These results provide

  3. Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests.

    Science.gov (United States)

    McIntosh, Anne C S; Macdonald, S Ellen; Quideau, Sylvie A

    2016-01-01

    Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand) scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover) and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs) and multiple carbon-source substrate-induced respiration (MSIR) of the forest floor microbial community) environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis) showed that two above-ground (mean tree diameter, litter cover) and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs) properties were associated with variation in understory plant community composition. These results provide novel insights

  4. Fine-scale features on bioreplicated decoys of the emerald ash borer provide necessary visual verisimilitude

    Science.gov (United States)

    Domingue, Michael J.; Pulsifer, Drew P.; Narkhede, Mahesh S.; Engel, Leland G.; Martín-Palma, Raúl J.; Kumar, Jayant; Baker, Thomas C.; Lakhtakia, Akhlesh

    2014-03-01

    The emerald ash borer (EAB), Agrilus planipennis, is an invasive tree-killing pest in North America. Like other buprestid beetles, it has an iridescent coloring, produced by a periodically layered cuticle whose reflectance peaks at 540 nm wavelength. The males perform a visually mediated ritualistic mating flight directly onto females poised on sunlit leaves. We attempted to evoke this behavior using artificial visual decoys of three types. To fabricate decoys of the first type, a polymer sheet coated with a Bragg-stack reflector was loosely stamped by a bioreplicating die. For decoys of the second type, a polymer sheet coated with a Bragg-stack reflector was heavily stamped by the same die and then painted green. Every decoy of these two types had an underlying black absorber layer. Decoys of the third type were produced by a rapid prototyping machine and painted green. Fine-scale features were absent on the third type. Experiments were performed in an American ash forest infested with EAB, and a European oak forest home to a similar pest, the two-spotted oak borer (TSOB), Agrilus biguttatus. When pinned to leaves, dead EAB females, dead TSOB females, and bioreplicated decoys of both types often evoked the complete ritualized flight behavior. Males also initiated approaches to the rapidly prototyped decoy, but would divert elsewhere without making contact. The attraction of the bioreplicated decoys was also demonstrated by providing a high dc voltage across the decoys that stunned and killed approaching beetles. Thus, true bioreplication with fine-scale features is necessary to fully evoke ritualized visual responses in insects, and provides an opportunity for developing insecttrapping technologies.

  5. Lack of sex-biased dispersal promotes fine-scale genetic structure in alpine ungulates

    Science.gov (United States)

    Roffler, Gretchen H.; Talbot, Sandra L.; Luikart, Gordon; Sage, George K.; Pilgrim, Kristy L.; Adams, Layne G.; Schwartz, Michael K.

    2014-01-01

    Identifying patterns of fine-scale genetic structure in natural populations can advance understanding of critical ecological processes such as dispersal and gene flow across heterogeneous landscapes. Alpine ungulates generally exhibit high levels of genetic structure due to female philopatry and patchy configuration of mountain habitats. We assessed the spatial scale of genetic structure and the amount of gene flow in 301 Dall’s sheep (Ovis dalli dalli) at the landscape level using 15 nuclear microsatellites and 473 base pairs of the mitochondrial (mtDNA) control region. Dall’s sheep exhibited significant genetic structure within contiguous mountain ranges, but mtDNA structure occurred at a broader geographic scale than nuclear DNA within the study area, and mtDNA structure for other North American mountain sheep populations. No evidence of male-mediated gene flow or greater philopatry of females was observed; there was little difference between markers with different modes of inheritance (pairwise nuclear DNA F ST = 0.004–0.325; mtDNA F ST = 0.009–0.544), and males were no more likely than females to be recent immigrants. Historical patterns based on mtDNA indicate separate northern and southern lineages and a pattern of expansion following regional glacial retreat. Boundaries of genetic clusters aligned geographically with prominent mountain ranges, icefields, and major river valleys based on Bayesian and hierarchical modeling of microsatellite and mtDNA data. Our results suggest that fine-scale genetic structure in Dall’s sheep is influenced by limited dispersal, and structure may be weaker in populations occurring near ancestral levels of density and distribution in continuous habitats compared to other alpine ungulates that have experienced declines and marked habitat fragmentation.

  6. Unresolved Fine-scale Structure in Solar Coronal Loop-tops

    Science.gov (United States)

    Scullion, E.; Rouppe van der Voort, L.; Wedemeyer, S.; Antolin, P.

    2014-12-01

    New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer substructures within coronal loop cross-sections, in order to understand the nature of the solar corona. Here, we push this lower limit further to search for the finest coronal loop substructures, through taking advantage of the resolving power of the Swedish 1 m Solar Telescope/CRisp Imaging Spectro-Polarimeter (CRISP), together with co-observations from the Solar Dynamics Observatory/Atmospheric Image Assembly (AIA). High-resolution imaging of the chromospheric Hα 656.28 nm spectral line core and wings can, under certain circumstances, allow one to deduce the topology of the local magnetic environment of the solar atmosphere where its observed. Here, we study post-flare coronal loops, which become filled with evaporated chromosphere that rapidly condenses into chromospheric clumps of plasma (detectable in Hα) known as a coronal rain, to investigate their fine-scale structure. We identify, through analysis of three data sets, large-scale catastrophic cooling in coronal loop-tops and the existence of multi-thermal, multi-stranded substructures. Many cool strands even extend fully intact from loop-top to footpoint. We discover that coronal loop fine-scale strands can appear bunched with as many as eight parallel strands within an AIA coronal loop cross-section. The strand number density versus cross-sectional width distribution, as detected by CRISP within AIA-defined coronal loops, most likely peaks at well below 100 km, and currently, 69% of the substructure strands are statistically unresolved in AIA coronal loops.

  7. Fine-scale population genetic structure in a fission-fusion society.

    Science.gov (United States)

    Archie, Elizabeth A; Maldonado, Jésus E; Hollister-Smith, Julie A; Poole, Joyce H; Moss, Cynthia J; Fleischer, Robert C; Alberts, Susan C

    2008-06-01

    Nonrandom patterns of mating and dispersal create fine-scale genetic structure in natural populations - especially of social mammals - with important evolutionary and conservation genetic consequences. Such structure is well-characterized for typical mammalian societies; that is, societies where social group composition is stable, dispersal is male-biased, and males form permanent breeding associations in just one or a few social groups over the course of their lives. However, genetic structure is not well understood for social mammals that differ from this pattern, including elephants. In elephant societies, social groups fission and fuse, and males never form permanent breeding associations with female groups. Here, we combine 33 years of behavioural observations with genetic information for 545 African elephants (Loxodonta africana), to investigate how mating and dispersal behaviours structure genetic variation between social groups and across age classes. We found that, like most social mammals, female matrilocality in elephants creates co-ancestry within core social groups and significant genetic differentiation between groups (Phi(ST) = 0.058). However, unlike typical social mammals, male elephants do not bias reproduction towards a limited subset of social groups, and instead breed randomly across the population. As a result, reproductively dominant males mediate gene flow between core groups, which creates cohorts of similar-aged paternal relatives across the population. Because poaching tends to eliminate the oldest elephants from populations, illegal hunting and poaching are likely to erode fine-scale genetic structure. We discuss our results and their evolutionary and conservation genetic implications in the context of other social mammals.

  8. Short-and long term niche segregation and individual specialization of brown trout (Salmo trutta) in species poor Faroese lakes

    DEFF Research Database (Denmark)

    Brodersen, Jakob; Malmquist, Hilmar J.; Landkildehus, Frank

    2012-01-01

    by comparing relative abundance, stable isotope ratios and diet in multiple habitats. In the presence of three-spined sticklebacks (Gasterosteus aculeatus), a higher proportion of the trout population was found in the pelagic habitat, and trout in general relied on a more pelagic diet base as compared to trout...... living in allopatry or in sympatry with Arctic charr (Salvelinus alpinus). Diet analyses revealed, however, that niche-segregation may be more complex than described on a one-dimensional pelagic-littoral axis. Trout from both littoral and offshore benthic habitats had in the presence of sticklebacks...... a less benthic diet as compared to trout living in allopatry or in sympatry with charr. Furthermore, we found individual habitat specialization between littoral/benthic and pelagic trout in deep lakes. Hence, our findings indicate that for trout populations interspecific competition can drive shifts...

  9. Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater.

    Science.gov (United States)

    Berlincourt, Maud; Angel, Lauren P; Arnould, John P Y

    2015-01-01

    Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals), is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1) resting on water, (2) flapping flight, (3) gliding flight, (4) foraging (i.e., surface foraging and diving events), and (5) taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1-70.0%) of time at sea resting on water and 18.2% (range: 2.3-49.6%) foraging. Individuals made 76.4 ± 65.3 dives (range: 8-237) per foraging trip (mean duration 9.0 ± 1.9 s), with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey.

  10. Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater.

    Directory of Open Access Journals (Sweden)

    Maud Berlincourt

    Full Text Available Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals, is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1 resting on water, (2 flapping flight, (3 gliding flight, (4 foraging (i.e., surface foraging and diving events, and (5 taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1-70.0% of time at sea resting on water and 18.2% (range: 2.3-49.6% foraging. Individuals made 76.4 ± 65.3 dives (range: 8-237 per foraging trip (mean duration 9.0 ± 1.9 s, with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey.

  11. Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater

    Science.gov (United States)

    Berlincourt, Maud; Angel, Lauren P.; Arnould, John P. Y.

    2015-01-01

    Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals), is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1) resting on water, (2) flapping flight, (3) gliding flight, (4) foraging (i.e., surface foraging and diving events), and (5) taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1–70.0%) of time at sea resting on water and 18.2% (range: 2.3–49.6%) foraging. Individuals made 76.4 ± 65.3 dives (range: 8–237) per foraging trip (mean duration 9.0 ± 1.9 s), with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey. PMID:26439491

  12. Integration of climatic water deficit and fine-scale physiography in process-based modeling of forest landscape resilience to large-scale tree mortality

    Science.gov (United States)

    Yang, J.; Weisberg, P.; Dilts, T.

    2016-12-01

    Climate warming can lead to large-scale drought-induced tree mortality events and greatly affect forest landscape resilience. Climatic water deficit (CWD) and its physiographic variations provide a key mechanism in driving landscape dynamics in response to climate change. Although CWD has been successfully applied in niche-based species distribution models, its application in process-based forest landscape models is still scarce. Here we present a framework incorporating fine-scale influence of terrain on ecohydrology in modeling forest landscape dynamics. We integrated CWD with a forest landscape succession and disturbance model (LANDIS-II) to evaluate how tree species distribution might shift in response to different climate-fire scenarios across an elevation-aspect gradient in a semi-arid montane landscape of northeastern Nevada, USA. Our simulations indicated that drought-intolerant tree species such as quaking aspen could experience greatly reduced distributions in the more arid portions of their existing ranges due to water stress limitations under future climate warming scenarios. However, even at the most xeric portions of its range, aspen is likely to persist in certain environmental settings due to unique and often fine-scale combinations of resource availability, species interactions and disturbance regime. The modeling approach presented here allowed identification of these refugia. In addition, this approach helped quantify how the direction and magnitude of fire influences on species distribution would vary across topoclimatic gradients, as well as furthers our understanding on the role of environmental conditions, fire, and inter-specific competition in shaping potential responses of landscape resilience to climate change.

  13. Chemical and morphological segregation of Alternaria arborescens, A-infectoria and A-tenuissima species-groups

    DEFF Research Database (Denmark)

    Andersen, Birgitte; Krøger, Elisabeth; Roberts, R.G.

    2002-01-01

    belonging to the genus Alternaria were examined. They were grown under standardised conditions and subjected to morphological and chemical examination. All isolates were grouped according to their three-dimensional sporulation pattern on potato carrot agar and their colony colour on dichloran rose bengal....... tenuissima species-groups with only a few metabolites in common. None of the 35 A. infectoria species-group isolates produced any known metabolites and all had white or greyish white colonies on DRYES. The A. arborescens species-group and the A. tenuissima species-group, shared most of the known metabolites...

  14. Heats of Segregation and Segregation Profiles of BCC Metals

    Science.gov (United States)

    Good, Brian S.; Bozzolo, Guillermo

    2002-01-01

    The composition of metal alloy surfaces is often different from that of the bulk. Some alloys exhibit surface segregation, where one or more species reside preferentially at or near the surface. A detailed understanding of this behavior is necessary to correctly model such phenomena as adhesion or catalysis. Several phenomenological approaches to the problem have been put forward, falling into two broad categories: Thermodynamic approaches, where the equilibrium distribution of chemical species is computed. Atomistic approaches, where the tendency of a species to segregate is determined by computation of the energies of single atoms of that species in bulk and surface environments.

  15. On Time/Space Aggregation of Fine-Scale Error Estimates (Invited)

    Science.gov (United States)

    Huffman, G. J.

    2013-12-01

    Estimating errors inherent in fine time/space-scale satellite precipitation data sets is still an on-going problem and a key area of active research. Complicating features of these data sets include the intrinsic intermittency of the precipitation in space and time and the resulting highly skewed distribution of precipitation rates. Additional issues arise from the subsampling errors that satellites introduce, the errors due to retrieval algorithms, and the correlated error that retrieval and merger algorithms sometimes introduce. Several interesting approaches have been developed recently that appear to make progress on these long-standing issues. At the same time, the monthly averages over 2.5°x2.5° grid boxes in the Global Precipitation Climatology Project (GPCP) Satellite-Gauge (SG) precipitation data set follow a very simple sampling-based error model (Huffman 1997) with coefficients that are set using coincident surface and GPCP SG data. This presentation outlines the unsolved problem of how to aggregate the fine-scale errors (discussed above) to an arbitrary time/space averaging volume for practical use in applications, reducing in the limit to simple Gaussian expressions at the monthly 2.5°x2.5° scale. Scatter diagrams with different time/space averaging show that the relationship between the satellite and validation data improves due to the reduction in random error. One of the key, and highly non-linear, issues is that fine-scale estimates tend to have large numbers of cases with points near the axes on the scatter diagram (one of the values is exactly or nearly zero, while the other value is higher). Averaging 'pulls' the points away from the axes and towards the 1:1 line, which usually happens for higher precipitation rates before lower rates. Given this qualitative observation of how aggregation affects error, we observe that existing aggregation rules, such as the Steiner et al. (2003) power law, only depend on the aggregated precipitation rate

  16. Microsatellite genetic diversity and fine-scale spatial genetic structure within a natural stand of Liriodendron chinense (Magnoliaceae in Lanmushan, Duyun City, Guizhou Province

    Directory of Open Access Journals (Sweden)

    Aihong Yang

    2014-05-01

    Full Text Available The Chinese tulip tree (Liriodendron chinense, an endangered species scattered throughout subtropical China and northern Vietnam, suffers from severe habitat fragmentation. Understanding the genetic diversity and fine-scale spatial genetic structure (SGS of fragmented populations is critical for developing successful conservation strategies for endangered species. In this study, we investigated the population genetic diversity and fine-scale spatial genetic structure in a wild, fragmented population of L. chinense using 13 polymorphic microsatellite loci. No significant differences in genetic diversity were found among habitat fragments or age classes (P > 0.05. Two genetically heterogeneous subpopulations were revealed through Bayesian assignment analysis and Principal Coordinates Analysis (PCoA. Significant SGS was found within the whole population within 200 m, while weak spatial aggregation of related individuals in the two subpopulations was found within 20 m. SGS intensity was weak in this population (Sp = 0.0090, and it was stronger in the village subpopulation (Sp = 0.0067 than in the hill subpopulation (Sp = 0.0053. Liriodendron chinense is a predominantly outcrossing tree and its winged seeds are wind-dispersed, a fact that may reduce SGS intensity in the species. Furthermore, low population density and flat hypsography also likely influence the SGS of L. chinense. The presence of significant heterozygote deficiency in the population (FIS = 0.099, P < 0.01 suggests a genetic signal of habitat fragmentation. Therefore, measures for promoting pollen flow should be taken for in situ conservation. For ex situ conservation, individuals should be sampled at 20 m apart to efficiently capture genetic diversity of wild populations.

  17. Fine-scale spatial genetic structure in the frankincense tree Boswellia papyrifera (Del.) Hochst. and implications for conservation

    NARCIS (Netherlands)

    Addisalem, A.B.; Duminil, J.; Wouters, D.; Bongers, F.; Smulders, M.J.M.

    2016-01-01

    The fine-scale genetic structure and how it varies between generations depends on the spatial scale of gene dispersal and other fundamental aspects of species’ biology, such as the mating system. Such knowledge is crucial for the design of genetic conservation strategies. This is particularly

  18. Fine-scale spatial genetic structure in the frankincense tree Boswellia papyrifera (Del.) Hochst. and implications for conservation

    NARCIS (Netherlands)

    Bekele, Addisalem; Duminil, J.; Wouters, D.; Bongers, F.; Smulders, M.J.M.

    2016-01-01

    The fine-scale genetic structure and how it varies between generations depends on the spatial scale of gene dispersal and other fundamental aspects of species’ biology, such as the mating system. Such knowledge is crucial for the design of genetic conservation strategies. This is particularly rel

  19. Fine-scale spatial genetic dynamics over the life cycle of the tropical tree Prunus africana.

    Science.gov (United States)

    Berens, D G; Braun, C; González-Martínez, S C; Griebeler, E M; Nathan, R; Böhning-Gaese, K

    2014-11-01

    Studying fine-scale spatial genetic patterns across life stages is a powerful approach to identify ecological processes acting within tree populations. We investigated spatial genetic dynamics across five life stages in the insect-pollinated and vertebrate-dispersed tropical tree Prunus africana in Kakamega Forest, Kenya. Using six highly polymorphic microsatellite loci, we assessed genetic diversity and spatial genetic structure (SGS) from seed rain and seedlings, and different sapling stages to adult trees. We found significant SGS in all stages, potentially caused by limited seed dispersal and high recruitment rates in areas with high light availability. SGS decreased from seed and early seedling stages to older juvenile stages. Interestingly, SGS was stronger in adults than in late juveniles. The initial decrease in SGS was probably driven by both random and non-random thinning of offspring clusters during recruitment. Intergenerational variation in SGS could have been driven by variation in gene flow processes, overlapping generations in the adult stage or local selection. Our study shows that complex sequential processes during recruitment contribute to SGS of tree populations.

  20. Dynamics of land change in India: a fine-scale spatial analysis

    Science.gov (United States)

    Meiyappan, P.; Roy, P. S.; Sharma, Y.; Jain, A. K.; Ramachandran, R.; Joshi, P. K.

    2015-12-01

    Land is scarce in India: India occupies 2.4% of worlds land area, but supports over 1/6th of worlds human and livestock population. This high population to land ratio, combined with socioeconomic development and increasing consumption has placed tremendous pressure on India's land resources for food, feed, and fuel. In this talk, we present contemporary (1985 to 2005) spatial estimates of land change in India using national-level analysis of Landsat imageries. Further, we investigate the causes of the spatial patterns of change using two complementary lines of evidence. First, we use statistical models estimated at macro-scale to understand the spatial relationships between land change patterns and their concomitant drivers. This analysis using our newly compiled extensive socioeconomic database at village level (~630,000 units), is 100x higher in spatial resolution compared to existing datasets, and covers over 200 variables. The detailed socioeconomic data enabled the fine-scale spatial analysis with Landsat data. Second, we synthesized information from over 130 survey based case studies on land use drivers in India to complement our macro-scale analysis. The case studies are especially useful to identify unobserved variables (e.g. farmer's attitude towards risk). Ours is the most detailed analysis of contemporary land change in India, both in terms of national extent, and the use of detailed spatial information on land change, socioeconomic factors, and synthesis of case studies.

  1. Fine scale mapping of the structure and composition of the Elkhorn Slough (California, USA) tidal plume

    Science.gov (United States)

    Fischer, Andrew M.; Ryan, John P.; Rienecker, Erich V.

    2017-01-01

    Fine scale mapping of the structure and composition of a tidal ebb plume from a highly modified coastal lagoon (Elkhorn Slough, California, USA) was conducted by combining in situ, observational data sets from surface underway mapping, autonomous underwater vehicle (AUV) profiles, drifter tracking and the analysis of plume structure indices. The results reveal a 6-m-deep, jet-like, sediment laden plume extending one km offshore at low tide, which becomes entrained in the prevailing nearshore circulation. The plume that exits the slough is significantly different from the water that enters the slough. The rapidly evolving discharge plume is associated with elevated and highly correlated (r = 0.93) concentrations of dissolved organic matter and nitrate. While dissolved constituents remain in the shallow plume and are transported northward with the prevailing current, sediment may settle quickly through the water column and can be transported southwestward with the littoral currents. This study illustrates the applications of AUVs, when coupled with additional datasets, for generating higher resolution observational snapshots of dynamic and ephemeral tidal plumes. The results provide unique perspective on small-scale dynamics of an estuarine plume and its influence on coastal ecology.

  2. Microsatellite analyses reveal fine-scale genetic structure in grey mouse lemurs (Microcebus murinus).

    Science.gov (United States)

    Fredsted, T; Pertoldi, C; Schierup, M H; Kappeler, P M

    2005-07-01

    Information on genetic structure can be used to complement direct inferences on social systems and behaviour. We studied the genetic structure of the solitary grey mouse lemur (Microcebus murinus), a small, nocturnal primate endemic to western Madagascar, with the aim of getting further insight on its breeding structure. Tissue samples from 167 grey mouse lemurs in an area covering 12.3 km2 in Kirindy Forest were obtained from trapping. The capture data indicated a noncontinuous distribution of individuals in the study area. Using 10 microsatellite markers, significant genetic differentiation in the study area was demonstrated and dispersal was found to be significantly male biased. Furthermore, we observed an overall excess of homozygotes in the total population (F(IT) = 0.131), which we interpret as caused by fine-scale structure with breeding occurring in small units. Evidence for a clumped distribution of identical homozygotes was found, supporting the notion that dispersal distance for breeding was shorter than that for foraging, i.e. the breeding neighbourhood size is smaller than the foraging neighbourhood size. In conclusion, we found a more complex population structure than what has been previously reported in studies performed on smaller spatial scales. The noncontinuous distribution of individuals and the effects of social variables on the genetic structure have implications for the interpretation of social organization and the planning of conservation activities that may apply to other solitary and endangered mammals as well.

  3. Fine-scale spatial ecology drives kin selection relatedness among cooperating amoebae.

    Science.gov (United States)

    Smith, Jeff; Strassmann, Joan E; Queller, David C

    2016-04-01

    Cooperation among microbes is important for traits as diverse as antibiotic resistance, pathogen virulence, and sporulation. The evolutionary stability of cooperation against "cheater" mutants depends critically on the extent to which microbes interact with genetically similar individuals. The causes of this genetic social structure in natural microbial systems, however, are unknown. Here, we show that social structure among cooperative Dictyostelium amoebae is driven by the population ecology of colonization, growth, and dispersal acting at spatial scales as small as fruiting bodies themselves. Despite the fact that amoebae disperse while grazing, all it takes to create substantial genetic clonality within multicellular fruiting bodies is a few millimeters distance between the cells colonizing a feeding site. Even adjacent fruiting bodies can consist of different genotypes. Soil populations of amoebae are sparse and patchily distributed at millimeter scales. The fine-scale spatial structure of cells and genotypes can thus account for the otherwise unexplained high genetic uniformity of spores in fruiting bodies from natural substrates. These results show how a full understanding of microbial cooperation requires understanding ecology and social structure at the small spatial scales microbes themselves experience.

  4. Population genomic footprints of fine-scale differentiation between habitats in Mediterranean blue tits.

    Science.gov (United States)

    Szulkin, M; Gagnaire, P-A; Bierne, N; Charmantier, A

    2016-01-01

    Linking population genetic variation to the spatial heterogeneity of the environment is of fundamental interest to evolutionary biology and ecology, in particular when phenotypic differences between populations are observed at biologically small spatial scales. Here, we applied restriction-site associated DNA sequencing (RAD-Seq) to test whether phenotypically differentiated populations of wild blue tits (Cyanistes caeruleus) breeding in a highly heterogeneous environment exhibit genetic structure related to habitat type. Using 12 106 SNPs in 197 individuals from deciduous and evergreen oak woodlands, we applied complementary population genomic analyses, which revealed that genetic variation is influenced by both geographical distance and habitat type. A fine-scale genetic differentiation supported by genome- and transcriptome-wide analyses was found within Corsica, between two adjacent habitats where blue tits exhibit marked differences in breeding time while nesting < 6 km apart. Using redundancy analysis (RDA), we show that genomic variation remains associated with habitat type when controlling for spatial and temporal effects. Finally, our results suggest that the observed patterns of genomic differentiation were not driven by a small proportion of highly differentiated loci, but rather emerged through a process such as habitat choice, which reduces gene flow between habitats across the entire genome. The pattern of genomic isolation-by-environment closely matches differentiation observed at the phenotypic level, thereby offering significant potential for future inference of phenotype-genotype associations in a heterogeneous environment.

  5. Mapping to Support Fine Scale Epidemiological Cholera Investigations: A Case Study of Spatial Video in Haiti

    Directory of Open Access Journals (Sweden)

    Andrew Curtis

    2016-02-01

    Full Text Available The cartographic challenge in many developing world environments suffering a high disease burden is a lack of granular environmental covariates suitable for modeling disease outcomes. As a result, epidemiological questions, such as how disease diffuses at intra urban scales are extremely difficult to answer. This paper presents a novel geospatial methodology, spatial video, which can be used to collect and map environmental covariates, while also supporting field epidemiology. An example of epidemic cholera in a coastal town of Haiti is used to illustrate the potential of this new method. Water risks from a 2012 spatial video collection are used to guide a 2014 survey, which concurrently included the collection of water samples, two of which resulted in positive lab results “of interest” (bacteriophage specific for clinical cholera strains to the current cholera situation. By overlaying sample sites on 2012 water risk maps, a further fifteen proposed water sample locations are suggested. These resulted in a third spatial video survey and an additional “of interest” positive water sample. A potential spatial connection between the “of interest” water samples is suggested. The paper concludes with how spatial video can be an integral part of future fine-scale epidemiological investigations for different pathogens.

  6. Fine-Scale Human Population Structure in Southern Africa Reflects Ecogeographic Boundaries.

    Science.gov (United States)

    Uren, Caitlin; Kim, Minju; Martin, Alicia R; Bobo, Dean; Gignoux, Christopher R; van Helden, Paul D; Möller, Marlo; Hoal, Eileen G; Henn, Brenna M

    2016-09-01

    Recent genetic studies have established that the KhoeSan populations of southern Africa are distinct from all other African populations and have remained largely isolated during human prehistory until ∼2000 years ago. Dozens of different KhoeSan groups exist, belonging to three different language families, but very little is known about their population history. We examine new genome-wide polymorphism data and whole mitochondrial genomes for >100 South Africans from the ≠Khomani San and Nama populations of the Northern Cape, analyzed in conjunction with 19 additional southern African populations. Our analyses reveal fine-scale population structure in and around the Kalahari Desert. Surprisingly, this structure does not always correspond to linguistic or subsistence categories as previously suggested, but rather reflects the role of geographic barriers and the ecology of the greater Kalahari Basin. Regardless of subsistence strategy, the indigenous Khoe-speaking Nama pastoralists and the N|u-speaking ≠Khomani (formerly hunter-gatherers) share ancestry with other Khoe-speaking forager populations that form a rim around the Kalahari Desert. We reconstruct earlier migration patterns and estimate that the southern Kalahari populations were among the last to experience gene flow from Bantu speakers, ∼14 generations ago. We conclude that local adoption of pastoralism, at least by the Nama, appears to have been primarily a cultural process with limited genetic impact from eastern Africa.

  7. Mapping to Support Fine Scale Epidemiological Cholera Investigations: A Case Study of Spatial Video in Haiti.

    Science.gov (United States)

    Curtis, Andrew; Blackburn, Jason K; Smiley, Sarah L; Yen, Minmin; Camilli, Andrew; Alam, Meer Taifur; Ali, Afsar; Morris, J Glenn

    2016-02-03

    The cartographic challenge in many developing world environments suffering a high disease burden is a lack of granular environmental covariates suitable for modeling disease outcomes. As a result, epidemiological questions, such as how disease diffuses at intra urban scales are extremely difficult to answer. This paper presents a novel geospatial methodology, spatial video, which can be used to collect and map environmental covariates, while also supporting field epidemiology. An example of epidemic cholera in a coastal town of Haiti is used to illustrate the potential of this new method. Water risks from a 2012 spatial video collection are used to guide a 2014 survey, which concurrently included the collection of water samples, two of which resulted in positive lab results "of interest" (bacteriophage specific for clinical cholera strains) to the current cholera situation. By overlaying sample sites on 2012 water risk maps, a further fifteen proposed water sample locations are suggested. These resulted in a third spatial video survey and an additional "of interest" positive water sample. A potential spatial connection between the "of interest" water samples is suggested. The paper concludes with how spatial video can be an integral part of future fine-scale epidemiological investigations for different pathogens.

  8. Integrating coarse-scale uncertain soil moisture data into a fine-scale hydrological modelling scenario

    Directory of Open Access Journals (Sweden)

    H. Vernieuwe

    2011-06-01

    Full Text Available In a hydrological modelling scenario, often the modeller is confronted with external data, such as remotely-sensed soil moisture observations, that become available to update the model output. However, the scale triplet (spacing, extent and support of these data is often inconsistent with that of the model. Furthermore, the external data can be cursed with epistemic uncertainty. Hence, a method is needed that not only integrates the external data into the model, but that also takes into account the difference in scale and the uncertainty of the observations. In this paper, a synthetic hydrological modelling scenario is set up in which a high-resolution distributed hydrological model is run over an agricultural field. At regular time steps, coarse-scale field-averaged soil moisture data, described by means of possibility distributions (epistemic uncertainty, are retrieved by synthetic aperture radar and assimilated into the model. A method is presented that allows to integrate the coarse-scale possibility distribution of soil moisture content data with the fine-scale model-based soil moisture data. To this end, a scaling relationship between field-averaged soil moisture content data and its corresponding standard deviation is employed.

  9. Modelling deep water habitats to develop a spatially explicit, fine scale understanding of the distribution of the western rock lobster, Panulirus cygnus.

    Directory of Open Access Journals (Sweden)

    Renae K Hovey

    Full Text Available BACKGROUND: The western rock lobster, Panulirus cygnus, is endemic to Western Australia and supports substantial commercial and recreational fisheries. Due to and its wide distribution and the commercial and recreational importance of the species a key component of managing western rock lobster is understanding the ecological processes and interactions that may influence lobster abundance and distribution. Using terrain analyses and distribution models of substrate and benthic biota, we assess the physical drivers that influence the distribution of lobsters at a key fishery site. METHODS AND FINDINGS: Using data collected from hydroacoustic and towed video surveys, 20 variables (including geophysical, substrate and biota variables were developed to predict the distributions of substrate type (three classes of reef, rhodoliths and sand and dominant biota (kelp, sessile invertebrates and macroalgae within a 40 km(2 area about 30 km off the west Australian coast. Lobster presence/absence data were collected within this area using georeferenced pots. These datasets were used to develop a classification tree model for predicting the distribution of the western rock lobster. Interestingly, kelp and reef were not selected as predictors. Instead, the model selected geophysical and geomorphic scalar variables, which emphasise a mix of terrain within limited distances. The model of lobster presence had an adjusted D(2 of 64 and an 80% correct classification. CONCLUSIONS: Species distribution models indicate that juxtaposition in fine scale terrain is most important to the western rock lobster. While key features like kelp and reef may be important to lobster distribution at a broad scale, it is the fine scale features in terrain that are likely to define its ecological niche. Determining the most appropriate landscape configuration and scale will be essential to refining niche habitats and will aid in selecting appropriate sites for protecting critical

  10. Inbreeding avoidance drives consistent variation of fine-scale genetic structure caused by dispersal in the seasonal mating system of Brandt's voles.

    Directory of Open Access Journals (Sweden)

    Xiao Hui Liu

    Full Text Available Inbreeding depression is a major evolutionary and ecological force influencing population dynamics and the evolution of inbreeding-avoidance traits such as mating systems and dispersal. Mating systems and dispersal are fundamental determinants of population genetic structure. Resolving the relationships among genetic structure, seasonal breeding-related mating systems and dispersal will facilitate our understanding of the evolution of inbreeding avoidance. The goals of this study were as follows: (i to determine whether females actively avoided mating with relatives in a group-living rodent species, Brandt's voles (Lasiopodomys brandtii, by combined analysis of their mating system, dispersal and genetic structure; and (ii to analyze the relationships among the variation in fine-genetic structure, inbreeding avoidance, season-dependent mating strategies and individual dispersal. Using both individual- and population-level analyses, we found that the majority of Brandt's vole groups consisted of close relatives. However, both group-specific FISs, an inbreeding coefficient that expresses the expected percentage rate of homozygosity arising from a given breeding system, and relatedness of mates showed no sign of inbreeding. Using group pedigrees and paternity analysis, we show that the mating system of Brandt's voles consists of a type of polygyny for males and extra-group polyandry for females, which may decrease inbreeding by increasing the frequency of mating among distantly-related individuals. The consistent variation in within-group relatedness, among-group relatedness and fine-scale genetic structures was mostly due to dispersal, which primarily occurred during the breeding season. Biologically relevant variation in the fine-scale genetic structure suggests that dispersal during the mating season may be a strategy to avoid inbreeding and drive the polygynous and extra-group polyandrous mating system of this species.

  11. Fine Scale ANUClimate Data for Ecosystem Modeling and Assessment of Plant Functional Types

    Science.gov (United States)

    Hutchinson, M. F.; Kesteven, J. L.; Xu, T.; Evans, B. J.; Togashi, H. F.; Stein, J. L.

    2015-12-01

    High resolution spatially extended values of climate variables play a central role in the assessment of climate and projected future climate in ecosystem modeling. The ground based meteorological network remains a key resource for deriving these spatially extended climate variables. We report on the production, and applications, of new anomaly based fine scale spatial interpolations of key climate variables at daily and monthly time scale, across the Australian continent. The methods incorporate several innovations that have significantly improved spatial predictive accuracy, as well as providing a platform for the incorporation of additional remotely sensed data. The interpolated climate data are supporting many continent-wide ecosystem modeling applications and are playing a key role in testing optimality hypotheses associated with plant functional types (PFTs). The accuracy, and robustness to data error, of anomaly-based interpolation has been enhanced by incorporating physical process aspects of the different climate variables and employing robust statistical methods implemented in the ANUSPLIN package. New regression procedures have also been developed to estimate "background" monthly climate normals from all stations with minimal records to substantially increase the density of supporting spatial networks. Monthly mean temperature interpolation has been enhanced by incorporating process based coastal effects that have reduced predictive error by around 10%. Overall errors in interpolated monthly temperature fields are around 25% less than errors reported by an earlier study. For monthly and daily precipitation, a new anomaly structure has been devised to take account of the skewness in precipitation data and the large proportion of zero values that present significant challenges to standard interpolation methods. The many applications include continent-wide Gross Primary Production modeling and assessing constraints on light and water use efficiency derived

  12. The fine-scale vertical variability of a wastewater plume in shallow, stratified coastal waters

    Science.gov (United States)

    Lucas, Andrew J.; Kudela, Raphael M.

    2017-02-01

    We observed the fine-scale vertical variability of a wastewater plume discharged into shallow, stratified coastal waters with a set of wave-powered profiling moorings and bottom-mounted Acoustic Doppler Current Profilers. These in situ observations demonstrated that the effluent plume occupied a variable portion of the water column, but was typically at or above the pycnocline. The plume was characterized by small vertical scales away from the surface, while complicated patterns of vertical temperature and salinity compensation were found in the plume above the pycnocline. The particular design of the diffuser led to an effluent plume that was roughly split between depth-trapped and trapped at the surface. Estimates of dilution from temperature/salinity diagrams indicated that the plume dilution ranged between 60 and 120, and that the environmental mixing end-members ranged from waters well below the pycnocline to the waters at or near the surface. Far from the outfall, oceanographic variability at frequencies equal to and higher than the diurnal frequency dominated the vertical shear in local currents and thus the vertical and temporal distribution of the plume. Mixing driven by the high frequency non-linear internal waves and bore-like manifestations of the cross-shore baroclinic tide, as suggested by elevated inverse Richardson number within the leading and trailing edge of the bores, was likely the primary source of mixing between the plume and ambient waters far from the outfall. Complicated patterns in plume water characteristics demonstrated the complexity of the plume dilution even in a surfacing plume. The co-occurrence of elevated chlorophyll fluorescence and plume waters was evident in the later part of the diversion period, but the overall response of the phytoplankton to the effluent diversion was limited. Implications for outfall wastewater monitoring and diffuser design are briefly considered.

  13. Regulation of the demographic structure in isomorphic biphasic life cycles at the spatial fine scale.

    Directory of Open Access Journals (Sweden)

    Vasco Manuel Nobre de Carvalho da Silva Vieira

    Full Text Available Isomorphic biphasic algal life cycles often occur in the environment at ploidy abundance ratios (Haploid:Diploid different from 1. Its spatial variability occurs within populations related to intertidal height and hydrodynamic stress, possibly reflecting the niche partitioning driven by their diverging adaptation to the environment argued necessary for their prevalence (evolutionary stability. Demographic models based in matrix algebra were developed to investigate which vital rates may efficiently generate an H:D variability at a fine spatial resolution. It was also taken into account time variation and type of life strategy. Ploidy dissimilarities in fecundity rates set an H:D spatial structure miss-fitting the ploidy fitness ratio. The same happened with ploidy dissimilarities in ramet growth whenever reproductive output dominated the population demography. Only through ploidy dissimilarities in looping rates (stasis, breakage and clonal growth did the life cycle respond to a spatially heterogeneous environment efficiently creating a niche partition. Marginal locations were more sensitive than central locations. Related results have been obtained experimentally and numerically for widely different life cycles from the plant and animal kingdoms. Spore dispersal smoothed the effects of ploidy dissimilarities in fertility and enhanced the effects of ploidy dissimilarities looping rates. Ploidy dissimilarities in spore dispersal could also create the necessary niche partition, both over the space and time dimensions, even in spatial homogeneous environments and without the need for conditional differentiation of the ramets. Fine scale spatial variability may be the key for the prevalence of isomorphic biphasic life cycles, which has been neglected so far.

  14. Air pollution, health and social deprivation: A fine-scale risk assessment.

    Science.gov (United States)

    Morelli, Xavier; Rieux, Camille; Cyrys, Josef; Forsberg, Bertil; Slama, Rémy

    2016-05-01

    Risk assessment studies often ignore within-city variations of air pollutants. Our objective was to quantify the risk associated with fine particulate matter (PM2.5) exposure in 2 urban areas using fine-scale air pollution modeling and to characterize how this risk varied according to social deprivation. In Grenoble and Lyon areas (0.4 and 1.2 million inhabitants, respectively) in 2012, PM2.5 exposure was estimated on a 10×10m grid by coupling a dispersion model to population density. Outcomes were mortality, lung cancer and term low birth weight incidences. Cases attributable to air pollution were estimated overall and stratifying areas according to the European Deprivation Index (EDI), taking 10µg/m(3) yearly average as reference (counterfactual) level. Estimations were repeated assuming spatial homogeneity of air pollutants within urban area. Median PM2.5 levels were 18.1 and 19.6μg/m(3) in Grenoble and Lyon urban areas, respectively, corresponding to 114 (5.1% of total, 95% confidence interval, CI, 3.2-7.0%) and 491 non-accidental deaths (6.0% of total, 95% CI 3.7-8.3%) attributable to long-term exposure to PM2.5, respectively. Attributable term low birth weight cases represented 23.6% of total cases (9.0-37.1%) in Grenoble and 27.6% of cases (10.7-42.6%) in Lyon. In Grenoble, 6.8% of incident lung cancer cases were attributable to air pollution (95% CI 3.1-10.1%). Risk was lower by 8 to 20% when estimating exposure through background stations. Risk was highest in neighborhoods with intermediate to higher social deprivation. Risk assessment studies relying on background stations to estimate air pollution levels may underestimate the attributable risk.

  15. Using fine-scale fuel measurements to assess wildland fuels, potential fire behavior and hazard mitigation treatments in the southeastern USA

    Science.gov (United States)

    Roger D. Ottmar; John I. Blake; William T. Crolly

    2012-01-01

    The inherent spatial and temporal heterogeneity of fuel beds in forests of the southeastern United States may require fine scale fuel measurements for providing reliable fire hazard and fuel treatment effectiveness estimates. In a series of five papers, an intensive, fine scale fuel inventory from the Savanna River Site in the southeastern United States is used for...

  16. Fine-scale refuges can buffer demographic and genetic processes against short-term climatic variation and disturbance: a 22-year case study of an arboreal marsupial.

    Science.gov (United States)

    Banks, Sam C; Lorin, Thibault; Shaw, Robyn E; McBurney, Lachlan; Blair, David; Blyton, Michaela D J; Smith, Annabel L; Pierson, Jennifer C; Lindenmayer, David B

    2015-08-01

    Ecological disturbance and climate are key drivers of temporal dynamics in the demography and genetic diversity of natural populations. Microscale refuges are known to buffer species' persistence against environmental change, but the effects of such refuges on demographic and genetic patterns in response to short-term environmental variation are poorly understood. We quantified demographic and genetic responses of mountain brushtail possums (Trichosurus cunninghami) to rainfall variability (1992-2013) and to a major wildfire. We hypothesized that there would be underlying differences in demographic and genetic processes between an unburnt mesic refuge and a topographically exposed zone that was burnt in 2009. Fire caused a 2-year decrease in survival in the burnt zone, but the population grew after the fire due to immigration, leading to increased expected heterozygosity. We documented a fire-related behavioural shift, where the rate of movement by individuals in the unburnt refuge to the burnt zone decreased after fire. Irrespective of the fire, there were long-term differences in demographic and genetic parameters between the mesic/unburnt refuge and the nonmesic/burnt zone. Survival was high and unaffected by rainfall in the refuge, but lower and rainfall-dependent in the nonmesic zone. Net movement of individuals was directional, from the mesic refuge to the nonmesic zone, suggesting fine-scale source-sink dynamics. There were higher expected heterozygosity (HE ) and temporal genetic stability in the refuge, but lower HE and marked temporal genetic structure in the exposed habitat, consistent with reduced generational overlap caused by elevated mortality and immigration. Thus, fine-scale refuges can mediate the short-term demographic and genetic effects of climate and ecological disturbance. © 2015 John Wiley & Sons Ltd.

  17. Natural selection drives the fine-scale divergence of a coevolutionary arms race involving a long-mouthed weevil and its obligate host plant

    Directory of Open Access Journals (Sweden)

    Toju Hirokazu

    2009-01-01

    Full Text Available Abstract Background One of the major recent advances in evolutionary biology is the recognition that evolutionary interactions between species are substantially differentiated among geographic populations. To date, several authors have revealed natural selection pressures mediating the geographically-divergent processes of coevolution. How local, then, is the geographic structuring of natural selection in coevolutionary systems? Results I examined the spatial scale of a "geographic selection mosaic," focusing on a system involving a seed-predatory insect, the camellia weevil (Curculio camelliae, and its host plant, the Japanese camellia (Camellia japonica. In this system, female weevils excavate camellia fruits with their extremely-long mouthparts to lay eggs into seeds, while camellia seeds are protected by thick pericarps. Quantitative evaluation of natural selection demonstrated that thicker camellia pericarps are significantly favored in some, but not all, populations within a small island (Yakushima Island, Japan; diameter ca. 30 km. At the extreme, camellia populations separated by only several kilometers were subject to different selection pressures. Interestingly, in a population with the thickest pericarps, camellia individuals with intermediate pericarp thickness had relatively high fitness when the potential costs of producing thick pericarps were considered. Also importantly, some parameters of the weevil - camellia interaction such as the severity of seed infestation showed clines along temperature, suggesting the effects of climate on the fine-scale geographic differentiation of the coevolutionary processes. Conclusion These results show that natural selection can drive the geographic differentiation of interspecific interactions at surprisingly small spatial scales. Future studies should reveal the evolutionary/ecological outcomes of the "fine scale geographic mosaics" in biological communities.

  18. Fine-Scale Microclimatic Variation Can Shape the Responses of Organisms to Global Change in Both Natural and Urban Environments.

    Science.gov (United States)

    Pincebourde, Sylvain; Murdock, Courtney C; Vickers, Mathew; Sears, Michael W

    2016-07-01

    abilities of ectotherms in setting their overall performance. We used a random walk framework to show that the thermal heterogeneity allows a more precise behavioral thermoregulation and a narrower temperature distribution of the ectotherm compared to less heterogeneous microhabitats. Finally, we discuss the potential impacts of global change on the fine scale mosaics of microclimates. The amplitude of change may differ between spatial scales. In heterogeneous microhabitats, the amplitude of change at micro-scale, caused by atmospheric warming, can be substantial while it can be limited at the local and landscape scales. We suggest that the warming signal will influence species performance and biotic interactions by modulating the mosaic of microclimates.

  19. Fine Scale Structure observed in the Total Electron Content above the Sub-Auroral, Auroral, and Polar Ionosphere

    Science.gov (United States)

    Coster, A. J.; Thomas, E. G.; Vierinen, J.; Rideout, W. E.

    2015-12-01

    This paper details recent improvements in TEC observations made in the sub-auroral, auroral, and polar regions. The goal is high-resolution measurements of both medium and fine-scale TEC-gradients. To achieve this, the number of GNSS receivers processed was more than doubled, due to agreements made with multiple government and commercial agencies, such as those involved with highway transportation and precision farming. Following the increase in GNSS observations, additional improvements were made in the MIT Haystack GNSS data processing algorithms, allowing for finer grid spacing of the output TEC data. Merging data sets also increased sensitivity. Scintillation data from several GNSS receivers have been overlaid on top of all-sky camera images showing evidence of aurora. These data sets have been merged with the measured background TEC to monitor the development both medium and fine-scale TEC gradients. Data from multiple geomagnetic storms and auroral events in this solar cycle will be presented.

  20. DETECTION OF A FINE-SCALE DISCONTINUITY OF PHOTOSPHERIC MAGNETIC FIELDS ASSOCIATED WITH SOLAR CORONAL LOOP BRIGHTENINGS

    Energy Technology Data Exchange (ETDEWEB)

    Song, Donguk; Chae, Jongchul; Park, Soyoung [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Cho, Kyung-Suk; Lim, Eun-Kyung [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Ahn, Kwangsu; Cao, Wenda [Big Bear Solar Observatory, New Jersey Institute of Technology, Big Bear City, CA 92314 (United States)

    2015-09-10

    We present the transient brightening of a coronal loop and an associated fine-scale magnetic discontinuity detected in the photosphere. Utilizing the high-resolution data taken with the Fast Imaging Solar Spectrograph and InfraRed Imaging Magnetograph of the New Solar Telescope at Big Bear Solar Observatory, we detect a narrow lane of intense horizontal magnetic field representing a magnetic discontinuity. It was visible as a dark lane partially encircling a pore in the continuum image, and was located near one of the footpoints of a small coronal loop that experienced transient brightenings. The horizontal field strength gradually increased before the loop brightening, and then rapidly decreased in the impulsive phase of the brightening, suggesting the increase of the magnetic non-potentiality at the loop footpoint and the sudden release of magnetic energy via magnetic reconnection. Our results support the nanoflare theory that coronal heating events are caused by magnetic reconnection events at fine-scale magnetic discontinuities.

  1. Introgression and Habitat Segregation in a Pair of Ladybird Beetle Species in the Genus Propylea (Coccinellidae, Coccinellinae) in Northern Japan.

    Science.gov (United States)

    Suga, Hiromu; Hirano, Wataru; Katoh, Toru; Matsubayashi, Kei W; Katakura, Haruo

    2016-12-01

    The ladybird beetles Propylea quatuordecimpunctata and P. japonica have largely overlapping distributions in northern Japan, and in the laboratory produce fertile hybrids. In this study, we surveyed the distribution and morphological differentiation of these species and the hybrids in natural populations, with a focus on western Hokkaido, northern Japan. Phenotypic analyses were conducted for 987 individuals collected at 90 localities. In addition, the nuclear internal transcribed spacer-II (ITS2) region (549 bp) and part of the mitochondrial cytochrome c oxidase subunit I (COI) gene (700 bp) were sequenced for 620 individuals from 53 localities. Analyses of both phenotypic and genotypic features discriminated two distinct entities assignable to P. quatuordecimpunctata and P. japonica. However, individuals with intermediate phenotypes and/or genotypes also occurred extensively, indicating natural hybridization. Putative P. quatuordecimpunctata individuals were collected across a wide range of altitudes (30-600 m), whereas those of P. japonica were found mostly lower than 300 m alt. In addition, P. quatuordecimpunctata was dominant in semi-open habitats shaded by canopy foliage, whereas P. japonica was frequent in more open habitats. The perceived altitudinal difference in the distributions may thus in part be a consequence of this different habitat preference, as open habitats are more common at lower altitudes in the study area.

  2. A nanobuffer reporter library for fine-scale imaging and perturbation of endocytic organelles | Office of Cancer Genomics

    Science.gov (United States)

    Endosomes, lysosomes and related catabolic organelles are a dynamic continuum of vacuolar structures that impact a number of cell physiological processes such as protein/lipid metabolism, nutrient sensing and cell survival. Here we develop a library of ultra-pH-sensitive fluorescent nanoparticles with chemical properties that allow fine-scale, multiplexed, spatio-temporal perturbation and quantification of catabolic organelle maturation at single organelle resolution to support quantitative investigation of these processes in living cells.

  3. Genetic Geostatistical Framework for Spatial Analysis of Fine-Scale Genetic Heterogeneity in Modern Populations: Results from the KORA Study

    OpenAIRE

    Diaz-Lacava, A. N.; Walier, M; D. Holler; Steffens, M; Gieger, C; C. Furlanello; Lamina, C; Wichmann, H E; Becker, T

    2015-01-01

    Aiming to investigate fine-scale patterns of genetic heterogeneity in modern humans from a geographic perspective, a genetic geostatistical approach framed within a geographic information system is presented. A sample collected for prospective studies in a small area of southern Germany was analyzed. None indication of genetic heterogeneity was detected in previous analysis. Socio-demographic and genotypic data of German citizens were analyzed (212 SNPs; n = 728). Genetic heterogeneity was ev...

  4. Fine Scale Spatiotemporal Clustering of Dengue Virus Transmission in Children and Aedes aegypti in Rural Thai Villages

    Science.gov (United States)

    2012-07-01

    Fine Scale Spatiotemporal Clustering of Dengue Virus Transmission in Children and Aedes aegypti in Rural Thai Villages In-Kyu Yoon1*, Arthur Getis2...between infected humans and Aedes aegypti in Thai villages. Methodology/Principal Findings: Geographic cluster investigations of 100-meter radius were...in rural Thailand. Child contacts and Ae. aegypti from cluster houses were assessed for DENV infection. Spatiotemporal, demographic, and entomological

  5. Fine-scale structure of the mid-mantle characterised by global stacks of PP precursors

    Science.gov (United States)

    Bentham, H. L. M.; Rost, S.; Thorne, M. S.

    2017-08-01

    Subduction zones are likely a major source of compositional heterogeneities in the mantle, which may preserve a record of the subduction history and mantle convection processes. The fine-scale structure associated with mantle heterogeneities can be studied using the scattered seismic wavefield that arrives as coda to or as energy preceding many body wave arrivals. In this study we analyse precursors to PP by creating stacks recorded at globally distributed stations. We create stacks aligned on the PP arrival in 5° distance bins (with range 70-120°) from 600 earthquakes recorded at 193 stations stacking a total of 7320 seismic records. As the energy trailing the direct P arrival, the P coda, interferes with the PP precursors, we suppress the P coda by subtracting a best fitting exponential curve to this energy. The resultant stacks show that PP precursors related to scattering from heterogeneities in the mantle are present for all distances. Lateral variations are explored by producing two regional stacks across the Atlantic and Pacific hemispheres, but we find only negligible differences in the precursory signature between these two regions. The similarity of these two regions suggests that well mixed subducted material can survive at upper and mid-mantle depth. To describe the scattered wavefield in the mantle, we compare the global stacks to synthetic seismograms generated using a Monte Carlo phonon scattering technique. We propose a best-fitting layered heterogeneity model, BRT2017, characterised by a three layer mantle with a background heterogeneity strength (ɛ = 0.8%) and a depth-interval of increased heterogeneity strength (ɛ = 1%) between 1000 km and 1800 km. The scalelength of heterogeneity is found to be 8 km throughout the mantle. Since mantle heterogeneity of 8 km scale may be linked to subducted oceanic crust, the detection of increased heterogeneity at mid-mantle depths could be associated with stalled slabs due to increases in viscosity

  6. Spatio-Temporal Effect on Soil Respiration in Fine-Scale Patches in a Desert Ecosystem

    Institute of Scientific and Technical Information of China (English)

    S. PEN-MOURATOV; M. RAKHIMBAEV; Y. STEINBERGER

    2006-01-01

    Soil organisms in terrestrial systems are unevenly distributed in time and space, and often aggregated. Spatiotemporal patchiness in the soil environment is thought to be crucial for the maintenance of soil biodiversity, providing diverse microhabitats tightly interweaving with resource partitioning. Determination of a "scale unit" to help understandecological processes has become one of the important and most debatable problems in recent years. A fieldwork was carried out in the northern Negev Desert highland, Israel to determine the influence of fine-scale landscape patch moisture heterogeneity on biogeochemical variables and microbial activity linkage in a desert ecosystem. The results showed that the spatio-temporal patchiness of soil moisture to which we attribute influential properties, was found to become more heterogenic with the decrease in soil moisture availability (from 8.2 to 0.4 g kg-1) toward the hot, dry seasons, with coefficient of variation (CV) change amounting to 66.9%. Spatio-temporal distribution of organic matter (OM) and total soluble nitrogen (TSN) was found to be relatively uniformly distributed throughout the wet seasons (winter and spring),with increase of relatively high heterogeneity toward the dry seasons (from 0.25% to 2.17% for OM, and from 0 to 10.2 mg kg-1 for TSN) with CV of 47.4% and 99.7% for OM and TSN, respectively. Different spatio-temporal landscape patterns were obtained for Ca (CV = 44.6%), K (CV = 34.4%), and Na (CV = 92%) ions throughout the study period. CO2evolution (CV = 48.6%) was found to be of lower heterogeneity (varying between 2 and 39 g CO2-C g-1 dry soil h-1) in the moist seasons, e.g., winter and spring, with lower values of respiration coupled with high heterogeneity of Na+ and low levels of TSN and organic matter content, and with more homogeneity in the dry seasons (varying between 1 and 50g CO2-C g-1 dry soil h-1). Our results elucidate the heterogeneity and complexity of desert system habitats affecting

  7. Assessment of Functional EST-SSR Markers (Sugarcane in Cross-Species Transferability, Genetic Diversity among Poaceae Plants, and Bulk Segregation Analysis

    Directory of Open Access Journals (Sweden)

    Shamshad Ul Haq

    2016-01-01

    Full Text Available Expressed sequence tags (ESTs are important resource for gene discovery, gene expression and its regulation, molecular marker development, and comparative genomics. We procured 10000 ESTs and analyzed 267 EST-SSRs markers through computational approach. The average density was one SSR/10.45 kb or 6.4% frequency, wherein trinucleotide repeats (66.74% were the most abundant followed by di- (26.10%, tetra- (4.67%, penta- (1.5%, and hexanucleotide (1.2% repeats. Functional annotations were done and after-effect newly developed 63 EST-SSRs were used for cross transferability, genetic diversity, and bulk segregation analysis (BSA. Out of 63 EST-SSRs, 42 markers were identified owing to their expansion genetics across 20 different plants which amplified 519 alleles at 180 loci with an average of 2.88 alleles/locus and the polymorphic information content (PIC ranged from 0.51 to 0.93 with an average of 0.83. The cross transferability ranged from 25% for wheat to 97.22% for Schlerostachya, with an average of 55.86%, and genetic relationships were established based on diversification among them. Moreover, 10 EST-SSRs were recognized as important markers between bulks of pooled DNA of sugarcane cultivars through BSA. This study highlights the employability of the markers in transferability, genetic diversity in grass species, and distinguished sugarcane bulks.

  8. North African hybrid sparrows (Passer domesticus, P. hispaniolensis) back from oblivion - ecological segregation and asymmetric mitochondrial introgression between parental species.

    Science.gov (United States)

    Ait Belkacem, Abdelkrim; Gast, Oliver; Stuckas, Heiko; Canal, David; LoValvo, Mario; Giacalone, Gabriele; Päckert, Martin

    2016-08-01

    A stabilized hybrid form of the house sparrow (Passer domesticus) and the Spanish sparrow (P. hispaniolensis) is known as Passer italiae from the Italian Peninsula and a few Mediterranean islands. The growing attention for the Italian hybrid sparrow and increasing knowledge on its biology and genetic constitution greatly contrast the complete lack of knowledge of the long-known phenotypical hybrid sparrow populations from North Africa. Our study provides new data on the breeding biology and variation of mitochondrial DNA in three Algerian populations of house sparrows, Spanish sparrows, and phenotypical hybrids. In two field seasons, the two species occupied different breeding habitats: Spanish sparrows were only found in rural areas outside the cities and bred in open-cup nests built in large jujube bushes. In contrast, house sparrows bred only in the town centers and occupied nesting holes in walls of buildings. Phenotypical hybrids were always associated with house sparrow populations. House sparrows and phenotypical hybrids started breeding mid of March, and most pairs had three successive clutches, whereas Spanish sparrows started breeding almost one month later and had only two successive clutches. Mitochondrial introgression is strongly asymmetric because about 75% of the rural Spanish sparrow population carried house sparrow haplotypes. In contrast, populations of the Italian hybrid form, P. italiae, were genetically least diverse among all study populations and showed a near-fixation of house sparrow haplotypes that elsewhere were extremely rare or that were even unique for the Italian Peninsula. Such differences between mitochondrial gene pools of Italian and North African hybrid sparrow populations provide first evidence that different demographic histories have shaped the extant genetic diversity observed on both continents.

  9. Demonstrating the Uneven Importance of Fine-Scale Forest Structure on Snow Distributions using High Resolution Modeling

    Science.gov (United States)

    Broxton, P. D.; Harpold, A. A.; van Leeuwen, W.; Biederman, J. A.

    2016-12-01

    Quantifying the amount of snow in forested mountainous environments, as well as how it may change due to warming and forest disturbance, is critical given its importance for water supply and ecosystem health. Forest canopies affect snow accumulation and ablation in ways that are difficult to observe and model. Furthermore, fine-scale forest structure can accentuate or diminish the effects of forest-snow interactions. Despite decades of research demonstrating the importance of fine-scale forest structure (e.g. canopy edges and gaps) on snow, we still lack a comprehensive understanding of where and when forest structure has the largest impact on snowpack mass and energy budgets. Here, we use a hyper-resolution (1 meter spatial resolution) mass and energy balance snow model called the Snow Physics and Laser Mapping (SnowPALM) model along with LIDAR-derived forest structure to determine where spatial variability of fine-scale forest structure has the largest influence on large scale mass and energy budgets. SnowPALM was set up and calibrated at sites representing diverse climates in New Mexico, Arizona, and California. Then, we compared simulations at different model resolutions (i.e. 1, 10, and 100 m) to elucidate the effects of including versus not including information about fine scale canopy structure. These experiments were repeated for different prescribed topographies (i.e. flat, 30% slope north, and south-facing) at each site. Higher resolution simulations had more snow at lower canopy cover, with the opposite being true at high canopy cover. Furthermore, there is considerable scatter, indicating that different canopy arrangements can lead to different amounts of snow, even when the overall canopy coverage is the same. This modeling is contributing to the development of a high resolution machine learning algorithm called the Snow Water Artificial Network (SWANN) model to generate predictions of snow distributions over much larger domains, which has implications

  10. Host identity matters in the amphibian-Batrachochytrium dendrobatidis system: fine-scale patterns of variation in responses to a multi-host pathogen.

    Science.gov (United States)

    Gervasi, Stephanie; Gondhalekar, Carmen; Olson, Deanna H; Blaustein, Andrew R

    2013-01-01

    Species composition within ecological assemblages can drive disease dynamics including pathogen invasion, spread, and persistence. In multi-host pathogen systems, interspecific variation in responses to infection creates important context dependency when predicting the outcome of disease. Here, we examine the responses of three sympatric host species to a single fungal pathogen, Batrachochytrium dendrobatidis, which is associated with worldwide amphibian population declines and extinctions. Using an experimental approach, we show that amphibian species from three different genera display significant differences in patterns of pathgen-induced mortality as well as the magnitude and temporal dynamics of infection load. We exposed amphibians to one of four inoculation dose treatments at both larval and post- metamorphic stages and quantified infection load on day 8 and day 15 post-inoculation. Of the three species examined, only one (the Pacific treefrog; Pseudacris regilla) displayed "dose-dependent" responses; survival was reduced and infection load was elevated as inoculation dose was increased. We observed a reduction in survival but no differences in infection load across pathogen treatments in Cascades frogs (Rana cascadae). Western toads (Anaxyrus boreas) displayed differences in infection load but no differences in survival across pathogen treatments. Within species, responses to the pathogen varied with life history stage, and the most heavily infected species at the larval stage was different from the most heavily infected species at the post-metamorphic stage. Temporal changes in infection load were species and life history stage-specific. We show that variation in susceptibility to this multi-host pathogen is complex when viewed at a fine-scale and may be mediated through intrinsic host traits.

  11. Host identity matters in the amphibian-Batrachochytrium dendrobatidis system: fine-scale patterns of variation in responses to a multi-host pathogen.

    Directory of Open Access Journals (Sweden)

    Stephanie Gervasi

    Full Text Available Species composition within ecological assemblages can drive disease dynamics including pathogen invasion, spread, and persistence. In multi-host pathogen systems, interspecific variation in responses to infection creates important context dependency when predicting the outcome of disease. Here, we examine the responses of three sympatric host species to a single fungal pathogen, Batrachochytrium dendrobatidis, which is associated with worldwide amphibian population declines and extinctions. Using an experimental approach, we show that amphibian species from three different genera display significant differences in patterns of pathgen-induced mortality as well as the magnitude and temporal dynamics of infection load. We exposed amphibians to one of four inoculation dose treatments at both larval and post- metamorphic stages and quantified infection load on day 8 and day 15 post-inoculation. Of the three species examined, only one (the Pacific treefrog; Pseudacris regilla displayed "dose-dependent" responses; survival was reduced and infection load was elevated as inoculation dose was increased. We observed a reduction in survival but no differences in infection load across pathogen treatments in Cascades frogs (Rana cascadae. Western toads (Anaxyrus boreas displayed differences in infection load but no differences in survival across pathogen treatments. Within species, responses to the pathogen varied with life history stage, and the most heavily infected species at the larval stage was different from the most heavily infected species at the post-metamorphic stage. Temporal changes in infection load were species and life history stage-specific. We show that variation in susceptibility to this multi-host pathogen is complex when viewed at a fine-scale and may be mediated through intrinsic host traits.

  12. Fine-scaling mapping of the gene responsible for multiple endocrine neoplasia type I (MEN1)

    Energy Technology Data Exchange (ETDEWEB)

    Fujimori, Minoru; Nakamura, Yusuke (Cancer Institute, Tokyo (Japan)); Wells, S.A. (Washington University School of Medicine, St. Louis (United States))

    1992-02-01

    The authors have constructed a high-resolution genetic linkage map in the vicinity of the gene responsible for multiple endocrine neoplasia type 1 (MEN1). The mutation causing this disease, inherited as an autosomal dominant, predisposes carriers to development of neoplastic tumors in the parathyroid, the endocrine pancreas, and the anterior lobe of the pituitary. The 12 markers on the genetic linkage map reported here span nearly 20 cM, and linkage analysis of MEN1 pedigrees has placed the MEN1 locus within the 8-cM region between D11S480 and D11S546. The markers on this map will be useful for prenatal or presymptomatic diagnosis of individuals in families that segregate a mutant allele of the MEN1 gene.

  13. Mechanisms for chromosome segregation.

    Science.gov (United States)

    Bouet, Jean-Yves; Stouf, Mathieu; Lebailly, Elise; Cornet, François

    2014-12-01

    Bacteria face the problem of segregating their gigantic chromosomes without a segregation period restricted in time and space, as Eukaryotes do. Segregation thus involves multiple activities, general or specific of a chromosome region and differentially controlled. Recent advances show that these various mechanisms conform to a “pair and release” rule, which appears as a general rule in DNA segregation. We describe the latest advances in segregation of bacterial chromosomes with emphasis on the different pair and release mechanisms.

  14. Fine-scale spatial and interannual cadmium isotope variability in the subarctic northeast Pacific

    Science.gov (United States)

    Janssen, D. J.; Abouchami, W.; Galer, S. J. G.; Cullen, J. T.

    2017-08-01

    that cannot be explained by a closed-system Rayleigh model. These results correspond with a warm water surface anomaly found along Line P in 2014 and demonstrate that there is interannual variability in the biogeochemical cycling of Cd and its isotopes in the subarctic North Pacific. In contrast to other ocean basins where vertical variability in ɛ 112 / 110Cd is observed at depth, deep and intermediate waters in the North Pacific have a near-uniform ɛ 112 / 110Cd value (mean of 1.14 ± 0.37, n = 43, 2SD) representative of nearly all samples at or below 1000 m depth. Imprinted upon this nearly homogeneous intermediate and deep North Pacific ɛ 112 / 110Cd signature are fine-scale spatial trends, with heavier values observed toward the coastal end of Line P than the oceanic end at intermediate depths, and with slightly heavier values in subtropical North Pacific deep water compared to the subarctic North Pacific. The nearly constant Cd isotopic composition of North Pacific deep waters is consistent with the inflow of Circumpolar Deep Water at depth in the Pacific basin, along with deep remineralization, and supports the potential of ɛ 112 / 110Cd as a tracer of global deepwater circulation.

  15. Reflectance anisotropy for characterising fine-scale changes in soil surface condition across different soil types

    Science.gov (United States)

    Croft, Holly; Anderson, Karen; Kuhn, Nikolaus J.

    2010-05-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in a reduction in soil productivity, an increased susceptibility to erosion and increased release of greenhouse gases. Soil surface roughness at the centimetre scale plays a fundamental role in affecting soil erosion and surface runoff pathways. A decline in surface roughness can also be used to infer soil degradation as soil aggregates are broken down through raindrop impact. However, due to the time and resources involved in using traditional field sampling techniques, there is a lack of spatially-distributed information on soil surface condition. Remotely sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Furthermore, a growing recognition into the importance of the directional reflectance domain has led to an increasing number of satellites with multiple view angle (MVA) capabilities (e.g. MISR, CHRIS on Proba). This is potentially useful for monitoring soil degradation and susceptibility to erosion because changes in soil surface roughness, associated with the breakdown of macro-aggregates, have a measurable effect on directional reflectance factors. Consequently, field and laboratory data are required for an empirical understanding of soil directional reflectance characteristics, underpinning subsequent model development. This study assessed the extent to which a hyperspectral MVA approach (350-2500 nm) could detect fine-scale changes in soil crusting states across five different soil types. A series of soil crusting states were produced for all five soil types, using an artificial rainfall simulator. The controlled conditions allowed the production of a series of stages in the soil crusting process; showing progressively declining surface roughness values. Each soil state was then spatially characterised, using a laboratory laser device at 2 mm sample spacing, over a 10 x 10 cm area. Laser data

  16. Mating system and gene flow in the red seaweed Gracilaria gracilis: effect of haploid-diploid life history and intertidal rocky shore landscape on fine-scale genetic structure.

    Science.gov (United States)

    Engel, C R; Destombe, C; Valero, M

    2004-04-01

    The impact of haploid-diploidy and the intertidal landscape on a fine-scale genetic structure was explored in a red seaweed Gracilaria gracilis. The pattern of genetic structure was compared in haploid and diploid stages at a microgeographic scale (shore. In this intertidal species, biased spore dispersal may occur during the transport of spores and gametes at low tide when small streams flow from high- to lower-shore pools. The longevity of both haploid and diploid free-living stages and the long generation times typical of G. gracilis populations may promote the observed pattern of high genetic diversity within populations relative to that among populations.

  17. Green light: gross primary production influences seasonal stream N export by controlling fine-scale temporal N dynamics

    Science.gov (United States)

    Bernal, S.; Lupon, A.; Sabater, F.; Martí Roca, E.

    2015-12-01

    The contribution of in-stream processes to nitrogen (N) exports remains unclear because stream water chemistry integrates biogeochemical processes occurring at different spatial and temporal scales within upland, riparian and aquatic ecosystems. Monitoring nutrient concentrations at fine-scale temporal resolution can provide insights on in-stream N processing. Yet, the mechanisms underlying fine-scale temporal nutrient dynamics and their implications for flux budgets at catchment scale are still poorly understood. Here, we investigated patterns and controls of diel variation in stream nitrate (NO3-) concentration and the influence of these on N fluxes along a stream continuum with increasing riparian area and channel width. We tested two alternative hypotheses: that diel variation in stream NO3- concentration is driven (a) by stream metabolism, or (b) by riparian groundwater inputs. Although productivity in this stream was extremely low, patterns of diel variation in stream NO3- concentration emerged in early-spring and they were highly correlated with the daily regime of irradiance and gross primary production (GPP). In addition, diel NO3- patterns agreed with those predicted from GPP and biofilm C:N ratios, but not with diel variations predicted from changes in riparian groundwater inputs. These results point at in-stream photoautotrophic N uptake as the most likely driver of diel fluctuations in stream NO3- concentration. From a network perspective, the occurrence of diel variations in stream NO3- concentration, and thus their influence on stream N fluxes, increased along the stream continuum likely because of increases in light inputs and water temperature. This study evidences that monitoring of nutrient concentrations at fine-scale temporal resolution can provide mechanistic explanations about the relevance of in-stream and terrestrial processes on regulating stream N dynamics and their contribution to N export at catchment scale.

  18. Fine-scale habitat structure complexity determines insectivorous bird diversity in a tropical forest

    Science.gov (United States)

    Castaño-Villa, Gabriel J.; Ramos-Valencia, Santiago A.; Fontúrbel, Francisco E.

    2014-11-01

    Habitat complexity in reforested stands has been acknowledged as a key factor that influences habitat use by birds, being especially critical for habitat disturbance-sensitive species such as tropical understory insectivorous birds. Most studies regarding the relationship between forest structure and species diversity were conducted at the landscape scale, but different diversity patterns may emerge at a finer scale (i.e., within a habitat patch). We examined a tropical reforested area (State of Caldas, Colombia), hypothesizing that insectivorous bird richness, abundance, and foraging guild abundance would increase as intra-habitat complexity increases. We established 40 monitoring plots within a reforested area, measured their structural features, and determined their relationships with species richness, total abundance, and foraging guild abundance, using Generalized Additive Models. We found that the increasing variation in basal area, stem diameter, and number of stems was positively correlated with species richness, total abundance, and foraging guild abundance. Relationships between richness or abundance and structural features were not lineal, but showing curvilinear responses and thresholds. Our results show that heterogeneity on basal area, stem diameter, and the number of stems was more correlated to insectivorous bird richness and abundance than the average of those structural features. Promoting structural variation on reforested areas by planting species with different growth rates may contribute to increase the richness and abundance of a tropical vulnerable group of species such as the understory insectivorous birds.

  19. Landscape management of fire and grazing regimes alters the fine-scale habitat utilisation by feral cats.

    Directory of Open Access Journals (Sweden)

    Hugh W McGregor

    Full Text Available Intensification of fires and grazing by large herbivores has caused population declines in small vertebrates in many ecosystems worldwide. Impacts are rarely direct, and usually appear driven via indirect pathways, such as changes to predator-prey dynamics. Fire events and grazing may improve habitat and/or hunting success for the predators of small mammals, however, such impacts have not been documented. To test for such an interaction, we investigated fine-scale habitat selection by feral cats in relation to fire, grazing and small-mammal abundance. Our study was conducted in north-western Australia, where small mammal populations are sensitive to changes in fire and grazing management. We deployed GPS collars on 32 cats in landscapes with contrasting fire and grazing treatments. Fine-scale habitat selection was determined using discrete choice modelling of cat movements. We found that cats selected areas with open grass cover, including heavily-grazed areas. They strongly selected for areas recently burnt by intense fires, but only in habitats that typically support high abundance of small mammals. Intense fires and grazing by introduced herbivores created conditions that are favoured by cats, probably because their hunting success is improved. This mechanism could explain why, in northern Australia, impacts of feral cats on small mammals might have increased. Our results suggest the impact of feral cats could be reduced in most ecosystems by maximising grass cover, minimising the incidence of intense fires, and reducing grazing by large herbivores.

  20. Landscape management of fire and grazing regimes alters the fine-scale habitat utilisation by feral cats.

    Science.gov (United States)

    McGregor, Hugh W; Legge, Sarah; Jones, Menna E; Johnson, Christopher N

    2014-01-01

    Intensification of fires and grazing by large herbivores has caused population declines in small vertebrates in many ecosystems worldwide. Impacts are rarely direct, and usually appear driven via indirect pathways, such as changes to predator-prey dynamics. Fire events and grazing may improve habitat and/or hunting success for the predators of small mammals, however, such impacts have not been documented. To test for such an interaction, we investigated fine-scale habitat selection by feral cats in relation to fire, grazing and small-mammal abundance. Our study was conducted in north-western Australia, where small mammal populations are sensitive to changes in fire and grazing management. We deployed GPS collars on 32 cats in landscapes with contrasting fire and grazing treatments. Fine-scale habitat selection was determined using discrete choice modelling of cat movements. We found that cats selected areas with open grass cover, including heavily-grazed areas. They strongly selected for areas recently burnt by intense fires, but only in habitats that typically support high abundance of small mammals. Intense fires and grazing by introduced herbivores created conditions that are favoured by cats, probably because their hunting success is improved. This mechanism could explain why, in northern Australia, impacts of feral cats on small mammals might have increased. Our results suggest the impact of feral cats could be reduced in most ecosystems by maximising grass cover, minimising the incidence of intense fires, and reducing grazing by large herbivores.

  1. Genetic Geostatistical Framework for Spatial Analysis of Fine-Scale Genetic Heterogeneity in Modern Populations: Results from the KORA Study

    Directory of Open Access Journals (Sweden)

    A. N. Diaz-Lacava

    2015-01-01

    Full Text Available Aiming to investigate fine-scale patterns of genetic heterogeneity in modern humans from a geographic perspective, a genetic geostatistical approach framed within a geographic information system is presented. A sample collected for prospective studies in a small area of southern Germany was analyzed. None indication of genetic heterogeneity was detected in previous analysis. Socio-demographic and genotypic data of German citizens were analyzed (212 SNPs; n=728. Genetic heterogeneity was evaluated with observed heterozygosity (HO. Best-fitting spatial autoregressive models were identified, using socio-demographic variables as covariates. Spatial analysis included surface interpolation and geostatistics of observed and predicted patterns. Prediction accuracy was quantified. Spatial autocorrelation was detected for both socio-demographic and genetic variables. Augsburg City and eastern suburban areas showed higher HO values. The selected model gave best predictions in suburban areas. Fine-scale patterns of genetic heterogeneity were observed. In accordance to literature, more urbanized areas showed higher levels of admixture. This approach showed efficacy for detecting and analyzing subtle patterns of genetic heterogeneity within small areas. It is scalable in number of loci, even up to whole-genome analysis. It may be suggested that this approach may be applicable to investigate the underlying genetic history that is, at least partially, embedded in geographic data.

  2. Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction.

    Science.gov (United States)

    Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

    2016-08-09

    Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps.

  3. Ecological Niche Modeling Identifies Fine-Scale Areas at High Risk of Dengue Fever in the Pearl River Delta, China

    Directory of Open Access Journals (Sweden)

    Qiaoxuan Li

    2017-06-01

    Full Text Available Dengue fever (DF is one of the most common and rapidly spreading mosquito-borne viral diseases in tropical and subtropical regions. In recent years, this imported disease has posed a serious threat to public health in China, especially in the Pearl River Delta (PRD. Although the severity of DF outbreaks in the PRD is generally associated with known risk factors, fine scale assessments of areas at high risk for DF outbreaks are limited. We built five ecological niche models to identify such areas including a variety of climatic, environmental, and socioeconomic variables, as well as, in some models, extracted principal components. All the models we tested accurately identified the risk of DF, the area under the receiver operating characteristic curve (AUC were greater than 0.8, but the model using all original variables was the most accurate (AUC = 0.906. Socioeconomic variables had a greater impact on this model (total contribution 55.27% than climatic and environmental variables (total contribution 44.93%. We found the highest risk of DF outbreaks on the border of Guangzhou and Foshan (in the central PRD, and in northern Zhongshan (in the southern PRD. Our fine-scale results may help health agencies to focus epidemic monitoring tightly on the areas at highest risk of DF outbreaks.

  4. Fine-scale nutrient and carbonate system dynamics around cold-water coral reefs in the northeast Atlantic.

    Science.gov (United States)

    Findlay, Helen S; Hennige, Sebastian J; Wicks, Laura C; Navas, Juan Moreno; Woodward, E Malcolm S; Roberts, J Murray

    2014-01-20

    Ocean acidification has been suggested as a serious threat to the future existence of cold-water corals (CWC). However, there are few fine-scale temporal and spatial datasets of carbonate and nutrients conditions available for these reefs, which can provide a baseline definition of extant conditions. Here we provide observational data from four different sites in the northeast Atlantic that are known habitats for CWC. These habitats differ by depth and by the nature of the coral habitat. At depths where CWC are known to occur across these sites the dissolved inorganic carbon ranged from 2088 to 2186 μmol kg(-1), alkalinity ranged from 2299 to 2346 μmol kg(-1), and aragonite Ω ranged from 1.35 to 2.44. At two sites fine-scale hydrodynamics caused increased variability in the carbonate and nutrient conditions over daily time-scales. The observed high level of variability must be taken into account when assessing CWC sensitivities to future environmental change.

  5. Fine-scale flight strategies of gulls in urban airflows indicate risk and reward in city living.

    Science.gov (United States)

    Shepard, Emily L C; Williamson, Cara; Windsor, Shane P

    2016-09-26

    Birds modulate their flight paths in relation to regional and global airflows in order to reduce their travel costs. Birds should also respond to fine-scale airflows, although the incidence and value of this remains largely unknown. We resolved the three-dimensional trajectories of gulls flying along a built-up coastline, and used computational fluid dynamic models to examine how gulls reacted to airflows around buildings. Birds systematically altered their flight trajectories with wind conditions to exploit updraughts over features as small as a row of low-rise buildings. This provides the first evidence that human activities can change patterns of space-use in flying birds by altering the profitability of the airscape. At finer scales still, gulls varied their position to select a narrow range of updraught values, rather than exploiting the strongest updraughts available, and their precise positions were consistent with a strategy to increase their velocity control in gusty conditions. Ultimately, strategies such as these could help unmanned aerial vehicles negotiate complex airflows. Overall, airflows around fine-scale features have profound implications for flight control and energy use, and consideration of this could lead to a paradigm-shift in the way ecologists view the urban environment.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

  6. Fine-scale ecological and economic assessment of climate change on olive in the Mediterranean Basin reveals winners and losers.

    Science.gov (United States)

    Ponti, Luigi; Gutierrez, Andrew Paul; Ruti, Paolo Michele; Dell'Aquila, Alessandro

    2014-04-15

    The Mediterranean Basin is a climate and biodiversity hot spot, and climate change threatens agro-ecosystems such as olive, an ancient drought-tolerant crop of considerable ecological and socioeconomic importance. Climate change will impact the interactions of olive and the obligate olive fruit fly (Bactrocera oleae), and alter the economics of olive culture across the Basin. We estimate the effects of climate change on the dynamics and interaction of olive and the fly using physiologically based demographic models in a geographic information system context as driven by daily climate change scenario weather. A regional climate model that includes fine-scale representation of the effects of topography and the influence of the Mediterranean Sea on regional climate was used to scale the global climate data. The system model for olive/olive fly was used as the production function in our economic analysis, replacing the commonly used production-damage control function. Climate warming will affect olive yield and fly infestation levels across the Basin, resulting in economic winners and losers at the local and regional scales. At the local scale, profitability of small olive farms in many marginal areas of Europe and elsewhere in the Basin will decrease, leading to increased abandonment. These marginal farms are critical to conserving soil, maintaining biodiversity, and reducing fire risk in these areas. Our fine-scale bioeconomic approach provides a realistic prototype for assessing climate change impacts in other Mediterranean agro-ecosystems facing extant and new invasive pests.

  7. Fine-scale nutrient and carbonate system dynamics around cold-water coral reefs in the northeast Atlantic

    Science.gov (United States)

    Findlay, Helen S.; Hennige, Sebastian J.; Wicks, Laura C.; Navas, Juan Moreno; Woodward, E. Malcolm S.; Roberts, J. Murray

    2014-01-01

    Ocean acidification has been suggested as a serious threat to the future existence of cold-water corals (CWC). However, there are few fine-scale temporal and spatial datasets of carbonate and nutrients conditions available for these reefs, which can provide a baseline definition of extant conditions. Here we provide observational data from four different sites in the northeast Atlantic that are known habitats for CWC. These habitats differ by depth and by the nature of the coral habitat. At depths where CWC are known to occur across these sites the dissolved inorganic carbon ranged from 2088 to 2186 μmol kg-1, alkalinity ranged from 2299 to 2346 μmol kg-1, and aragonite Ω ranged from 1.35 to 2.44. At two sites fine-scale hydrodynamics caused increased variability in the carbonate and nutrient conditions over daily time-scales. The observed high level of variability must be taken into account when assessing CWC sensitivities to future environmental change.

  8. Fine-scale flight strategies of gulls in urban airflows indicate risk and reward in city living

    Science.gov (United States)

    Shepard, Emily L. C.

    2016-01-01

    Birds modulate their flight paths in relation to regional and global airflows in order to reduce their travel costs. Birds should also respond to fine-scale airflows, although the incidence and value of this remains largely unknown. We resolved the three-dimensional trajectories of gulls flying along a built-up coastline, and used computational fluid dynamic models to examine how gulls reacted to airflows around buildings. Birds systematically altered their flight trajectories with wind conditions to exploit updraughts over features as small as a row of low-rise buildings. This provides the first evidence that human activities can change patterns of space-use in flying birds by altering the profitability of the airscape. At finer scales still, gulls varied their position to select a narrow range of updraught values, rather than exploiting the strongest updraughts available, and their precise positions were consistent with a strategy to increase their velocity control in gusty conditions. Ultimately, strategies such as these could help unmanned aerial vehicles negotiate complex airflows. Overall, airflows around fine-scale features have profound implications for flight control and energy use, and consideration of this could lead to a paradigm-shift in the way ecologists view the urban environment. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’. PMID:27528784

  9. Fine-scale population dynamics in a marine fish species inferred from dynamic state-space models.

    Science.gov (United States)

    Rogers, Lauren A; Storvik, Geir O; Knutsen, Halvor; Olsen, Esben M; Stenseth, Nils C

    2017-07-01

    Identifying the spatial scale of population structuring is critical for the conservation of natural populations and for drawing accurate ecological inferences. However, population studies often use spatially aggregated data to draw inferences about population trends and drivers, potentially masking ecologically relevant population sub-structure and dynamics. The goals of this study were to investigate how population dynamics models with and without spatial structure affect inferences on population trends and the identification of intrinsic drivers of population dynamics (e.g. density dependence). Specifically, we developed dynamic, age-structured, state-space models to test different hypotheses regarding the spatial structure of a population complex of coastal Atlantic cod (Gadus morhua). Data were from a 93-year survey of juvenile (age 0 and 1) cod sampled along >200 km of the Norwegian Skagerrak coast. We compared two models: one which assumes all sampled cod belong to one larger population, and a second which assumes that each fjord contains a unique population with locally determined dynamics. Using the best supported model, we then reconstructed the historical spatial and temporal dynamics of Skagerrak coastal cod. Cross-validation showed that the spatially structured model with local dynamics had better predictive ability. Furthermore, posterior predictive checks showed that a model which assumes one homogeneous population failed to capture the spatial correlation pattern present in the survey data. The spatially structured model indicated that population trends differed markedly among fjords, as did estimates of population parameters including density-dependent survival. Recent biomass was estimated to be at a near-record low all along the coast, but the finer scale model indicated that the decline occurred at different times in different regions. Warm temperatures were associated with poor recruitment, but local changes in habitat and fishing pressure may have played a role in driving local dynamics. More generally, we demonstrated how state-space models can be used to test evidence for population spatial structure based on survey time-series data. Our study shows the importance of considering spatially structured dynamics, as the inferences from such an approach can lead to a different ecological understanding of the drivers of population declines, and fundamentally different management actions to restore populations. © 2017 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

  10. Fine-scale spatio-temporal variation in tiger Panthera tigris diet: Effect of study duration and extent on estimates of tiger diet in Chitwan National Park, Nepal

    Science.gov (United States)

    Kapfer, Paul M.; Streby, Henry M.; Gurung, B.; Simcharoen, A.; McDougal, C.C.; Smith, J.L.D.

    2011-01-01

    Attempts to conserve declining tiger Panthera tigris populations and distributions have experienced limited success. The poaching of tiger prey is a key threat to tiger persistence; a clear understanding of tiger diet is a prerequisite to conserve dwindling populations. We used unpublished data on tiger diet in combination with two previously published studies to examine fine-scale spatio-temporal changes in tiger diet relative to prey abundance in Chitwan National Park, Nepal, and aggregated data from the three studies to examine the effect that study duration and the size of the study area have on estimates of tiger diet. Our results correspond with those of previous studies: in all three studies, tiger diet was dominated by members of Cervidae; small to medium-sized prey was important in one study. Tiger diet was unrelated to prey abundance, and the aggregation of studies indicates that increasing study duration and study area size both result in increased dietary diversity in terms of prey categories consumed, and increasing study duration changed which prey species contributed most to tiger diet. Based on our results, we suggest that managers focus their efforts on minimizing the poaching of all tiger prey, and that future studies of tiger diet be of long duration and large spatial extent to improve our understanding of spatio-temporal variation in estimates of tiger diet. ?? 2011 Wildlife Biology, NKV.

  11. Genome-wide SNPs reveal fine-scale differentiation among wingless alpine stonefly populations and introgression between winged and wingless forms.

    Science.gov (United States)

    Dussex, Nicolas; Chuah, Aaron; Waters, Jonathan M

    2016-01-01

    Insect flight loss is a repeated phenomenon in alpine habitats, where wing reduction is thought to enhance local recruitment and increase fecundity. One predicted consequence of flight loss is reduced dispersal ability, which should lead to population genetic differentiation and perhaps ultimately to speciation. Using a dataset of 15,123 SNP loci, we present comparative analyses of fine-scale population structure in codistributed Zelandoperla stonefly species, across three parallel altitudinal transects in New Zealand's Rock and Pillar mountain range. We find that winged populations (altitude 200-500 m; Zelandoperla decorata) show no genetic structuring within or among streams, suggesting substantial dispersal mediated by flight. By contrast, wingless populations (Zelandoperla fenestrata; altitude 200-1100 m) exhibit distinct genetic clusters associated with each stream, and additional evidence of isolation by distance within streams. Our data support the hypothesis that wing-loss can initiate diversification in alpine insect populations over small spatial scales. The often deep phylogenetic placement of lowland Z. fenestrata within their stream-specific clades suggests the possibility of independent alpine colonization events for each stream. Additionally, the detection of winged, interspecific hybrid individuals raises the intriguing possibility that a previously flightless lineage could reacquire flight via introgression.

  12. Fine-scale thermal adaptation in a green turtle nesting population

    NARCIS (Netherlands)

    Weber, Sam B.; Broderick, Annette C.; Groothuis, Ton G. G.; Ellick, Jacqui; Godley, Brendan J.; Blount, Jonathan D.

    2012-01-01

    The effect of climate warming on the reproductive success of ectothermic animals is currently a subject of major conservation concern. However, for many threatened species, we still know surprisingly little about the extent of naturally occurring adaptive variation in heat-tolerance. Here, we show t

  13. Fine-scale thermal adaptation in a green turtle nesting population

    NARCIS (Netherlands)

    Weber, Sam B.; Broderick, Annette C.; Groothuis, Ton G. G.; Ellick, Jacqui; Godley, Brendan J.; Blount, Jonathan D.

    2012-01-01

    The effect of climate warming on the reproductive success of ectothermic animals is currently a subject of major conservation concern. However, for many threatened species, we still know surprisingly little about the extent of naturally occurring adaptive variation in heat-tolerance. Here, we show t

  14. Investigations of fine-scale phylogeography in Tigriopus californicus reveal historical patterns of population divergence

    OpenAIRE

    Ladner Jason T; Willett Christopher S

    2009-01-01

    Abstract Background The intertidal copepod Tigriopus californicus is a model for studying the process of genetic divergence in allopatry and for probing the nature of genetic changes that lead to reproductive isolation. Although previous studies have revealed a pattern of remarkably high levels of genetic divergence between the populations of this species at several spatial scales, it is not clear what types of historical processes are responsible. Particularly lacking are data that can yield...

  15. Fine-scale geographical origin of an insect pest invading North America.

    Directory of Open Access Journals (Sweden)

    Takahiro Hosokawa

    Full Text Available Invasive species may rapidly spread throughout new areas once introduced, which may potentially lead to serious damage to local fauna and flora. Information on geographical origins, introduction routes, and biology in native regions of such invasive species is of critical importance in identifying means of transport, preventing reintroduction, and establishing control/eradication methods. The plataspid stinkbug Megacopta cribraria, known as kudzu bug, recently invaded North America and now has become not only an agricultural pest of soybean but also a nuisance pest. Here we investigate the geographical origin of the invasive M. cribraria populations. Phylogeographical analyses based on 8.7 kb mitochondrial DNA sequences of the introduced and East Asian native Megacopta populations identified a well-supported clade consisting of the introduced populations and M. punctatissima populations in the Kyushu region of Japan, which strongly suggests that the invading M. cribraria populations are derived from a M. punctatissima population in the Kyushu region. Therefore, the region is proposed as a promising source of natural enemies for biological control of the invasive pest. Based on the phylogenetic information, relationship and treatment of the two Megacopta species are discussed.

  16. Identifying Where REDD+ Financially Out-Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach.

    Directory of Open Access Journals (Sweden)

    Nicola K Abram

    Full Text Available Reducing Emissions from Deforestation and forest Degradation (REDD+ aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional fine-scale and coarse-scale analyses (through carbon mapping and economic modelling to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD+ could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e would enable REDD+ to outcompete oil-palm in 55% of the unprotected forests requiring US $27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e would increase the competitiveness of REDD+ within the landscape but would still only capture between 69%-74% of the unprotected forest, requiring US $380-416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia. Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by

  17. Identifying Where REDD+ Financially Out-Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach.

    Science.gov (United States)

    Abram, Nicola K; MacMillan, Douglas C; Xofis, Panteleimon; Ancrenaz, Marc; Tzanopoulos, Joseph; Ong, Robert; Goossens, Benoit; Koh, Lian Pin; Del Valle, Christian; Peter, Lucy; Morel, Alexandra C; Lackman, Isabelle; Chung, Robin; Kler, Harjinder; Ambu, Laurentius; Baya, William; Knight, Andrew T

    2016-01-01

    Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional fine-scale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD+ could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e) would enable REDD+ to outcompete oil-palm in 55% of the unprotected forests requiring US $27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69%-74% of the unprotected forest, requiring US $380-416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD

  18. Identifying Where REDD+ Financially Out-Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach

    Science.gov (United States)

    MacMillan, Douglas C.; Xofis, Panteleimon; Ancrenaz, Marc; Tzanopoulos, Joseph; Ong, Robert; Goossens, Benoit; Koh, Lian Pin; Del Valle, Christian; Peter, Lucy; Morel, Alexandra C.; Lackman, Isabelle; Chung, Robin; Kler, Harjinder; Ambu, Laurentius; Baya, William; Knight, Andrew T.

    2016-01-01

    Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional fine-scale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD+ could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e) would enable REDD+ to outcompete oil-palm in 55% of the unprotected forests requiring US $27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69%-74% of the unprotected forest, requiring US $380–416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD

  19. Is substrate composition a suitable predictor for deep-water coral occurrence on fine scales?

    Science.gov (United States)

    Bennecke, Swaantje; Metaxas, Anna

    2017-06-01

    Species distribution modelling can be applied to identify potentially suitable habitat for species with largely unknown distributions, such as many deep-water corals. Important variables influencing species occurrence in the deep sea, e.g. substrate composition, are often not included in these modelling approaches because high-resolution data are unavailable. We investigated the relationship between substrate composition and the occurrence of the two deep-water octocoral species Primnoa resedaeformis and Paragorgia arborea, which require hard substrate for attachment. On a scale of 10s of metres, we analysed images of the seafloor taken at two locations inside the Northeast Channel Coral Conservation Area in the Northwest Atlantic. We interpolated substrate composition over the sampling areas and determined the contribution of substrate classes, depth and slope to describe habitat suitability using maximum entropy modelling (Maxent). Substrate composition was similar at both sites - dominated by pebbles in a matrix of sand (>80%) with low percentages of suitable substrate for coral occurrence. Coral abundance was low at site 1 (0.9 colonies of P. resedaeformis per 100 m2) and high at site 2 (63 colonies of P. resedaeformis per 100 m2) indicating that substrate alone is not sufficient to explain varying patterns in coral occurrence. Spatial interpolations of substrate classes revealed the difficulty to accurately resolve sparsely distributed boulders (3-5% of substrate). Boulders were by far the most important variable in the habitat suitability model (HSM) for P. resedaeformis at site 1, indicating the fundamental influence of a substrate class that is the least abundant. At site 2, HSMs identified cobbles and sand/pebble as the most important variables for habitat suitability. However, substrate classes were correlated making it difficult to determine the influence of individual variables. To provide accurate information on habitat suitability for the two coral

  20. What do we learn on bromoform transport and chemistry in deep convection from fine scale modelling?

    Directory of Open Access Journals (Sweden)

    V. Marécal

    2011-11-01

    Full Text Available Bromoform is one of the main sources of halogenated Very Short-Lived Species (VSLS that possibly contributes when degradated to the inorganic halogen loading in the stratosphere. Because of its short lifetime of about four weeks, its pathway to the stratosphere is mainly the transport by convection up to the tropical tropopause layer (TTL and then by radiative ascent in the low stratosphere. Some of its degradation product gases (PGs that are soluble can be scavenged and not reach the TTL.

    In this paper we present a detailed modelling study of the transport and the degradation of bromoform and its PGs in convection. We use a 3-D-cloud resolving model coupled with a chemistry model including gaseous and aqueous chemistry. We run idealised simulations up to 10 days, initialised using a tropical radiosounding for atmospheric conditions and using outputs from a global chemistry-transport model for chemical species. Bromoform is initialised only in the low levels. The first simulation is run with stable atmospheric conditions. It shows that the sum of the bromoform and its PGs significantly decreases with time because of dry deposition and that PGs are mainly in the form of HBr after 2 days of simulation. The other simulation is similar to the first simulation but includes perturbations of temperature and of moisture leading to the development of a convective cloud reaching the TTL. Results of this simulation show an efficient vertical transport of the bromoform from the boundary layer in the upper troposphere and TTL (mixing ratio up to 45% of the initial boundary layer mixing ratio. The organic PGs, which are for the most abundant of them not very soluble, are also uplifted efficiently. For the inorganic PGs, which are more abundant than organic PGs, their mixing ratios in the upper troposphere and in the TTL depend on the partitioning between inorganic soluble and inorganic non soluble species in the convective cloud. Important soluble

  1. Hyper-temporal LiDAR for tracking fine-scale changes in vegetation structure, phenology, and physiology

    Science.gov (United States)

    Magney, T. S.; Vierling, L. A.; Eitel, J.; Greaves, H.

    2015-12-01

    Vegetation three-dimensional (3-D) structure is inherently dynamic - plants alter both the allocation of resources within the canopy and branch/shoot morphology at short time-steps to acclimate to local environmental conditions and maximize photosynthetic potential. However, 3-D structure is often ignored in ecological studies because it is difficult to characterize using traditional field methods. Terrestrial laser scanning (TLS) is a rapidly maturing technique to complement and enhance traditional field methods for quantifying 3-D geometric properties of ecosystems. Two major limitations of TLS include the low temporal resolution that often exists between each data acquisition, and the relatively high cost of such systems (entry level systems cost >$40,000 USD) that puts this method out of reach for many potential users. Consequently, TLS is currently limited as a mainstream method for capturing 3-D geometric ecosystem dynamics. Over the last several years, we have been developing a field-ready autonomously operating terrestrial laser scanner (ATLS) capable of monitoring fine-scale changes in vegetation structure on a daily time-step. We will present an overview of recent findings using the ATLS to track changes in vegetation structure in low-stature ecosystems - from cropping system dynamics to Arctic tundra phenology. Further, we will discuss the potential for laser intensity return information from both an ATLS and TLS to track changes in plant phenology and physiology (Chlorophyll content, photoprotective mechanisms, moisture) that occur simultaneously - or prior to - changes in vegetation structure. Our results suggest that fine-scale mapping of plant structure, phenology, and physiology using information from TLS and ATLS could provide new insights into vegetation dynamics in space and time.

  2. Distribution and fine-scale spatial-genetic structure in British wild cherry (Prunus avium L.).

    Science.gov (United States)

    Vaughan, S P; Cottrell, J E; Moodley, D J; Connolly, T; Russell, K

    2007-05-01

    Insights into the within-population spatial-genetic structure (SGS) of forest tree species, where little is known regarding seed and pollen dispersal patterns, enhance understanding of their ecology and provide information of value in conservation and breeding. This study utilised 13 polymorphic simple sequence repeat loci to investigate the impact of asexual recruitment, management regime and tree size on the development of SGS in wild cherry (Prunus avium L). Only 246 genotypes were identified in the 551 trees sampled, reflecting significant levels of clonal reproduction in both managed and unmanaged populations. Naturally regenerated wild cherry was spatially aggregated under both management regimes. However, in the managed population, sexually derived trees accounted for a greater proportion of the smaller size classes, whereas vegetatively produced trees dominated the smaller size classes in the unmanaged population. High overall SGS values (Sp 0.030-Sp 0.045) were observed when considering only sexually derived genets and kinship coefficients were significant up to the 120 m distance class for both populations. The inclusion of clonal ramets in the analysis significantly increased the overall SGS (Sp 0.089-Sp 0.119) as well as kinship coefficients in the 40-80 m distance classes, illustrating the dramatic impact of vegetative propagation on SGS in this species. Increased spatial aggregation and regeneration appeared to be concomitant with increased SGS in the 40 m distance class in the unmanaged population. Neighbourhood size estimates were relatively small for both populations and kinship coefficients were found to decline with distance under both management regimes, suggesting that common mechanisms may restrict gene dispersal in wild cherry.

  3. Testing sexual segregation and aggregation: old ways are best.

    Science.gov (United States)

    Bonenfant, Christophe; Gaillard, Jean-michel; Dray, Stéphane; Loison, Anne; Royer, Manuela; Chessel, Daniel

    2007-12-01

    The study of sexual segregation has received increasing attention over the last two decades. Several hypotheses have been proposed to explain the existence of sexual segregation, such as the "predation risk hypothesis," the "forage selection hypothesis," and the "activity budget hypothesis." Testing which hypothesis drives sexual segregation is hampered, however, by the lack of consensus regarding a formal measurement of sexual segregation. By using a derivation of the well-known chi-square (here called the sexual segregation and aggregation statistic [SSAS]) instead of existent segregation coefficients, we offer a reliable way to test for temporal variation in the occurrence of sexual segregation and aggregation, even in cases where a large proportion of animals are observed alone. A randomization procedure provides a test for the null hypothesis of independence of the distributions of males and females among the groups. The usefulness of SSAS in the study of sexual segregation is demonstrated with three case studies on ungulate populations belonging to species with contrasting life histories and annual grouping patterns (isard, red deer, and roe deer). The existent segregation coefficients were unreliable since, for a given value, sexual segregation could or could not occur. Similarly, the existent segregation coefficients performed badly when males and females aggregated. The new SSAS was not prone to such limitations and allowed clear conclusions regarding whether males and females segregate, aggregate, or simply mix at random applicable to all species.

  4. Population genomics of an endemic Mediterranean fish: differentiation by fine scale dispersal and adaptation

    Science.gov (United States)

    Carreras, Carlos; Ordóñez, Víctor; Zane, Lorenzo; Kruschel, Claudia; Nasto, Ina; Macpherson, Enrique; Pascual, Marta

    2017-01-01

    The assessment of the genetic structuring of biodiversity is crucial for management and conservation. For species with large effective population sizes a low number of markers may fail to identify population structure. A solution of this shortcoming can be high-throughput sequencing that allows genotyping thousands of markers on a genome-wide approach while facilitating the detection of genetic structuring shaped by selection. We used Genotyping-by-Sequencing (GBS) on 176 individuals of the endemic East Atlantic peacock wrasse (Symphodus tinca), from 6 locations in the Adriatic and Ionian seas. We obtained a total of 4,155 polymorphic SNPs and we observed two strong barriers to gene flow. The first one differentiated Tremiti Islands, in the northwest, from all the other locations while the second one separated east and south-west localities. Outlier SNPs potentially under positive selection and neutral SNPs both showed similar patterns of structuring, although finer scale differentiation was unveiled with outlier loci. Our results reflect the complexity of population genetic structure and demonstrate that both habitat fragmentation and positive selection are on play. This complexity should be considered in biodiversity assessments of different taxa, including non-model yet ecologically relevant organisms. PMID:28262802

  5. Fine-scale phylogeographic structure of Borrelia lusitaniae revealed by multilocus sequence typing.

    Directory of Open Access Journals (Sweden)

    Liliana R Vitorino

    Full Text Available Borrelia lusitaniae is an Old World species of the Lyme borreliosis (LB group of tick-borne spirochetes and prevails mainly in countries around the Mediterranean Basin. Lizards of the family Lacertidae have been identified as reservoir hosts of B. lusitaniae. These reptiles are highly structured geographically, indicating limited migration. In order to examine whether host geographic structure shapes the evolution and epidemiology of B. lusitaniae, we analyzed the phylogeographic population structure of this tick-borne bacterium using a recently developed multilocus sequence typing (MLST scheme based on chromosomal housekeeping genes. A total of 2,099 questing nymphal and adult Ixodes ricinus ticks were collected in two climatically different regions of Portugal, being approximately 130 km apart. All ticks were screened for spirochetes by direct PCR. Attempts to isolate strains yielded 16 cultures of B. lusitaniae in total. Uncontaminated cultures as well as infected ticks were included in this study. The results using MLST show that the regional B. lusitaniae populations constitute genetically distinct populations. In contrast, no clear phylogeographic signals were detected in sequences of the commonly used molecular markers ospA and ospC. The pronounced population structure of B. lusitaniae over a short geographic distance as captured by MLST of the housekeeping genes suggests that the migration rates of B. lusitaniae are rather low, most likely because the distribution of mediterranean lizard populations is highly parapatric. The study underlines the importance of vertebrate hosts in the geographic spread of tick-borne microparasites.

  6. Fine-scale phylogeographic structure of Borrelia lusitaniae revealed by multilocus sequence typing.

    Science.gov (United States)

    Vitorino, Liliana R; Margos, Gabriele; Feil, Edward J; Collares-Pereira, Margarida; Zé-Zé, Libia; Kurtenbach, Klaus

    2008-01-01

    Borrelia lusitaniae is an Old World species of the Lyme borreliosis (LB) group of tick-borne spirochetes and prevails mainly in countries around the Mediterranean Basin. Lizards of the family Lacertidae have been identified as reservoir hosts of B. lusitaniae. These reptiles are highly structured geographically, indicating limited migration. In order to examine whether host geographic structure shapes the evolution and epidemiology of B. lusitaniae, we analyzed the phylogeographic population structure of this tick-borne bacterium using a recently developed multilocus sequence typing (MLST) scheme based on chromosomal housekeeping genes. A total of 2,099 questing nymphal and adult Ixodes ricinus ticks were collected in two climatically different regions of Portugal, being approximately 130 km apart. All ticks were screened for spirochetes by direct PCR. Attempts to isolate strains yielded 16 cultures of B. lusitaniae in total. Uncontaminated cultures as well as infected ticks were included in this study. The results using MLST show that the regional B. lusitaniae populations constitute genetically distinct populations. In contrast, no clear phylogeographic signals were detected in sequences of the commonly used molecular markers ospA and ospC. The pronounced population structure of B. lusitaniae over a short geographic distance as captured by MLST of the housekeeping genes suggests that the migration rates of B. lusitaniae are rather low, most likely because the distribution of mediterranean lizard populations is highly parapatric. The study underlines the importance of vertebrate hosts in the geographic spread of tick-borne microparasites.

  7. Fine-scale thermal adaptation in a green turtle nesting population

    Science.gov (United States)

    Weber, Sam B.; Broderick, Annette C.; Groothuis, Ton G. G.; Ellick, Jacqui; Godley, Brendan J.; Blount, Jonathan D.

    2012-01-01

    The effect of climate warming on the reproductive success of ectothermic animals is currently a subject of major conservation concern. However, for many threatened species, we still know surprisingly little about the extent of naturally occurring adaptive variation in heat-tolerance. Here, we show that the thermal tolerances of green turtle (Chelonia mydas) embryos in a single, island-breeding population have diverged in response to the contrasting incubation temperatures of nesting beaches just a few kilometres apart. In natural nests and in a common-garden rearing experiment, the offspring of females nesting on a naturally hot (black sand) beach survived better and grew larger at hot incubation temperatures compared with the offspring of females nesting on a cooler (pale sand) beach nearby. These differences were owing to shallower thermal reaction norms in the hot beach population, rather than shifts in thermal optima, and could not be explained by egg-mediated maternal effects. Our results suggest that marine turtle nesting behaviour can drive adaptive differentiation at remarkably fine spatial scales, and have important implications for how we define conservation units for protection. In particular, previous studies may have underestimated the extent of adaptive structuring in marine turtle populations that may significantly affect their capacity to respond to environmental change. PMID:21937495

  8. Fine-scale population genetic structure in Alaskan Pacific halibut (Hippoglossus stenolepis)

    Science.gov (United States)

    2010-01-01

    Pacific halibut collected in the Aleutian Islands, Bering Sea and Gulf of Alaska were used to test the hypothesis of genetic panmixia for this species in Alaskan marine waters. Nine microsatellite loci and sequence data from the mitochondrial (mtDNA) control region were analyzed. Eighteen unique mtDNA haplotypes were found with no evidence of geographic population structure. Using nine microsatellite loci, significant heterogeneity was detected between Aleutian Island Pacific halibut and fish from the other two regions (FST range = 0.007–0.008). Significant FST values represent the first genetic evidence of divergent groups of halibut in the central and western Aleutian Archipelago. No significant genetic differences were found between Pacific halibut in the Gulf of Alaska and the Bering Sea leading to questions about factors contributing to separation of Aleutian halibut. Previous studies have reported Aleutian oceanographic conditions at deep inter-island passes leading to ecological discontinuity and unique community structure east and west of Aleutian passes. Aleutian Pacific halibut genetic structure may result from oceanographic transport mechanisms acting as partial barriers to gene flow with fish from other Alaskan waters.

  9. Fine-scale genetic structure of Eremosparton songoricum and implication for conservation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Eremosparton songoricum (Litv.) Vass. is a clonal shrub that reproduces both asexually by under-ground rhizomes and sexually by seeds. It is now a rare species with a narrow distribution in fragmented habitat patches in the Gurbantunggut Desert of Xinjiang, China. The objective of this study was to determine the spatial pattern or structure of genetic variation within population. The within-populations genetic structure of E. songoricum in a plot (10 m×10 m) was analyzed using inter simple sequence repeats (ISSR) markers. Correlograms of Moran’s I showed significant positive value was about 7 m, but changed into a negative correlation with the increase of distance, indicating strong genetic structure. The natural character of clonal reproduction, restricted seed and pollen dispersal were the main factors of influencing the spatial pattern. The knowledge of clonal structures within populations was crucial for understanding evolutionary processes and ecological adaptation. This study provided basic data for the conservation and management of E. songoricum, especially for sampling strategies for ex situ conservation.

  10. Bacterial chromosome segregation.

    Science.gov (United States)

    Possoz, Christophe; Junier, Ivan; Espeli, Olivier

    2012-01-01

    Dividing cells have mechanisms to ensure that their genomes are faithfully segregated into daughter cells. In bacteria, the description of these mechanisms has been considerably improved in the recent years. This review focuses on the different aspects of bacterial chromosome segregation that can be understood thanks to the studies performed with model organisms: Escherichia coli, Bacillus subtilis, Caulobacter crescentus and Vibrio cholerae. We describe the global positionning of the nucleoid in the cell and the specific localization and dynamics of different chromosomal loci, kinetic and biophysic aspects of chromosome segregation are presented. Finally, a presentation of the key proteins involved in the chromosome segregation is made.

  11. Fine-scale pathways used by adult sea lampreys during riverine spawning migrations

    Science.gov (United States)

    Holbrook, Christopher; Bergstedt, Roger A.; Adams, Noah S.; Hatton, Tyson; McLaughlin, Robert L.

    2015-01-01

    Better knowledge of upstream migratory patterns of spawning Sea Lampreys Petromyzon marinus, an invasive species in the Great Lakes, is needed to improve trapping for population control and assessment. Although trapping of adult Sea Lampreys provides the basis for estimates of lake-wide abundance that are used to evaluate the Sea Lamprey control program, traps have only been operated at dams due to insufficient knowledge of Sea Lamprey behavior in unobstructed channels. Acoustic telemetry and radiotelemetry were used to obtain movement tracks for 23 Sea Lampreys in 2008 and 18 Sea Lampreys in 2009 at two locations in the Mississagi River, Ontario. Cabled hydrophone arrays provided two-dimensional geographic positions from acoustic transmitters at 3-s intervals; depth-encoded radio tag detections provided depths. Upstream movements occurred at dusk or during the night (2015–0318 hours). Sea Lampreys were closely associated with the river bottom and showed some preference to move near banks in shallow glide habitats, suggesting that bottom-oriented gears could selectively target adult Sea Lampreys in some habitats. However, Sea Lampreys were broadly distributed across the river channel, suggesting that the capture efficiency of nets and traps in open channels would depend heavily on the proportion of the channel width covered. Lack of vertical movements into the water column may have reflected lamprey preference for low water velocities, suggesting that energy conservation was more beneficial for lampreys than was vertical searching in rivers. Improved understanding of Sea Lamprey movement will assist in the development of improved capture strategies for their assessment and control in the Great Lakes.

  12. Landscape genetic analyses reveal fine-scale effects of forest fragmentation in an insular tropical bird.

    Science.gov (United States)

    Khimoun, Aurélie; Peterman, William; Eraud, Cyril; Faivre, Bruno; Navarro, Nicolas; Garnier, Stéphane

    2017-07-20

    Within the framework of landscape genetics, resistance surface modelling is particularly relevant to explicitly test competing hypotheses about landscape effects on gene flow. To investigate how fragmentation of tropical forest affects population connectivity in a forest specialist bird species, we optimized resistance surfaces without a priori specification, using least-cost (LCP) or resistance (IBR) distances. We implemented a two-step procedure in order (i) to objectively define the landscape thematic resolution (level of detail in classification scheme to describe landscape variables) and spatial extent (area within the landscape boundaries) and then (ii) to test the relative role of several landscape features (elevation, roads, land cover) in genetic differentiation in the Plumbeous Warbler (Setophaga plumbea). We detected a small-scale reduction of gene flow mainly driven by land cover, with a negative impact of the nonforest matrix on landscape functional connectivity. However, matrix components did not equally constrain gene flow, as their conductivity increased with increasing structural similarity with forest habitat: urban areas and meadows had the highest resistance values whereas agricultural areas had intermediate resistance values. Our results revealed a higher performance of IBR compared to LCP in explaining gene flow, reflecting suboptimal movements across this human-modified landscape, challenging the common use of LCP to design habitat corridors and advocating for a broader use of circuit theory modelling. Finally, our results emphasize the need for an objective definition of landscape scales (landscape extent and thematic resolution) and highlight potential pitfalls associated with parameterization of resistance surfaces. © 2017 John Wiley & Sons Ltd.

  13. Fine scale gene flow and individual movements among subpopulations of Centrolene prosoblepon (Anura: Centrolenidae

    Directory of Open Access Journals (Sweden)

    Jeanne M Robertson

    2008-03-01

    Full Text Available Dispersal capabilities determine and maintain local gene flow, and this has implications for population persistence and/or recolonization following environmental perturbations (natural or anthropogenic, disease outbreaks, or other demographic collapses. To predict recolonization and understand dispersal capacity in a stream-breeding frog, we examined individual movement patterns and gene flow among four subpopulations of the Neotropical glassfrog, Centrolene prosoblepon, at a mid-elevation cloud forest site at El Copé, Panama. We measured male movement directly during a two year mark-recapture study, and indirectly with gene flow estimates from mitochondrial DNA sequences (mtDNA. Individuals of this species showed strong site fidelity: over two years, male frogs in all four headwater streams moved very little (mean = 2.33 m; mode = 0 m. Nine individuals changed streams within one or two years, moving 675-1 108 m. For those males moving more than 10 m, movement was biased upstream (p ST = 0.007, p = 0.325 but gene flow was more limited across greater distances (CT = 0.322, p = 0.065, even within the same drainage network. Lowland populations of C. prosoblepon potentially act as an important source of colonists for upland populations in this watershed. Rev. Biol. Trop. 56 (1: 13-26. Epub 2008 March 31.La capacidad de dispersión determina y mantiene el flujo genético local, y esto tiene implicaciones para la persistencia poblacional y/o la recolonización que sigue a perturbaciones ambientales. Examinamos patrones individuales de movimiento y flujo genético entre subpoblaciones de Centrolene prosoblepon (Anura: Centrolenidae en un sitio de elevación media en El Copé, Panamá. Medimos directamente el movimiento de los machos durante un estudio de marcado-recaptura, e indirectamente con estimaciones de flujo genético a partir de secuencias de ADN mitocondrial (mtDNA. Los individuos mostraron fuerte fidelidad a su lugar: por más de dos a

  14. Effects of land use and fine-scale environmental heterogeneity on net ecosystem production over a temperate coniferous forest landscape

    Science.gov (United States)

    Turner, David P.; Guzy, Michael; Lefsky, Michael A.; van Tuyl, Steve; Sun, Osbert; Daly, Chris; Law, Beverly E.

    2003-04-01

    In temperate coniferous forests, spatial variation in net ecosystem production (NEP) is often associated with variation in stand age and heterogeneity in environmental factors such as soil depth. However, coarse spatial resolution analyses used to evaluate the terrestrial contribution to global NEP do not generally incorporate these effects. In this study, a fine-scale (25 m grid) analysis of NEP over a 164-km2 area of productive coniferous forests in the Pacific Northwest region of the United States was made to evaluate the effects of including fine scale information in landscape-scale NEP assessments. The Enhanced Thematic Mapper (ETM+) sensor resolved five cover classes in the study area and further differentiated between young, mature and old-growth conifer stands. ETM+ was also used to map current leaf area index (LAI) based on an empirical relationship of observed LAI to spectral vegetation indices. A daily time step climatology, based on 18 years of meteorological observations, was distributed (1 km resolution) over the mountainous terrain of the study area using the DAYMET model. Estimates of carbon pools and flux associated with soil, litter, coarse woody debris and live trees were then generated by running a carbon cycle model (Biome-BGC) to a state that reflected the current successional status and LAI of each grid cell, as indicated by the remote sensing observations. Estimated annual NEP for 1997 over the complete study area averaged 230 g C m-2, with most of the area acting as a carbon sink. The area-wide NEP is strongly positive because of reduced harvesting in the last decade and the recovery of areas harvested between 1940 and 1990. The average value was greater than would be indicated if the entire area was assumed to be a mature conifer stand, as in a coarse-scale analysis. The mean NEP varied interannually by over a factor of two. This variation was 38% less than the interannual variation for a single point. The integration of process models

  15. Identification of independent association signals and putative functional variants for breast cancer risk through fine-scale mapping of the 12p11 locus

    DEFF Research Database (Denmark)

    Zeng, Chenjie; Guo, Xingyi; Long, Jirong

    2016-01-01

    BACKGROUND: Multiple recent genome-wide association studies (GWAS) have identified a single nucleotide polymorphism (SNP), rs10771399, at 12p11 that is associated with breast cancer risk. METHOD: We performed a fine-scale mapping study of a 700 kb region including 441 genotyped and more than 1300...

  16. Fine-Scale Mapping at 9p22.2 Identifies Candidate Causal Variants That Modify Ovarian Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

    DEFF Research Database (Denmark)

    Vigorito, E.; Kuchenbaecker, Karoline B; Beesley, J

    2016-01-01

    Population-based genome wide association studies have identified a locus at 9p22.2 associated with ovarian cancer risk, which also modifies ovarian cancer risk in BRCA1 and BRCA2 mutation carriers. We conducted fine-scale mapping at 9p22.2 to identify potential causal variants in BRCA1 and BRCA2 ...

  17. Fine-scale mapping of type I allergy candidate loci suggests central susceptibility genes on chromosomes 3q, 4q and Xp

    DEFF Research Database (Denmark)

    Haagerup, A; Børglum, A D; Binderup, H G;

    2004-01-01

    and prevention. Like for other complex disorders, achievement of the knowledge necessary depends on confirmation of reported genomic candidate regions. METHODS: We performed a two-stage fine-scale linkage analysis in 11 selected candidate regions on chromosome 3p, 3q, 4p, 4q, 5q, 6p, 9p, 12q, 12qter, 18q and Xp...

  18. The fine-scale genetic structure of the malaria vectors Anopheles funestus and Anopheles gambiae (Diptera: Culicidae) in the north-eastern part of Tanzania

    NARCIS (Netherlands)

    Gélin, P.; Magalon, H.; Drakeley, C.; Maxwell, C.; Magesa, S.; Takken, W.; Boëte, C.

    2016-01-01

    Understanding the impact of altitude and ecological heterogeneity at a fine scale on the populations of malaria vectors is essential to better understand and anticipate eventual epidemiological changes. It could help to evaluate the spread of alleles conferring resistance to insecticides and also

  19. Identification of independent association signals and putative functional variants for breast cancer risk through fine-scale mapping of the 12p11 locus

    NARCIS (Netherlands)

    C. Zeng (Chenjie); Guo, X. (Xingyi); J. Long (Jirong); K.B. Kuchenbaecker (Karoline); A. Droit (Arnaud); K. Michailidou (Kyriaki); M. Ghoussaini (Maya); S. Kar (Siddhartha); Freeman, A. (Adam); J.L. Hopper (John); R.L. Milne (Roger); M.K. Bolla (Manjeet K.); Wang, Q. (Qin); J. Dennis (Joe); S. Agata (Simona); S. Ahmed (Shahana); K. Aittomäki (Kristiina); I.L. Andrulis (Irene); H. Anton-Culver (Hoda); Antonenkova, N.N. (Natalia N.); A. Arason (Adalgeir); Arndt, V. (Volker); B.K. Arun (Banu); B. Arver (Brita Wasteson); F. Bacot (Francois); D. Barrowdale (Daniel); Baynes, C. (Caroline); A. Beeghly-Fadiel (Alicia); J. Benítez (Javier); M. Bermisheva (Marina); C. Blomqvist (Carl); W.J. Blot (William); N.V. Bogdanova (Natalia); S.E. Bojesen (Stig); B. Bonnani (Bernardo); A.-L. Borresen-Dale (Anne-Lise); J.S. Brand (Judith S.); H. Brauch (Hiltrud); P. Brennan (Paul); H. Brenner (Hermann); A. Broeks (Annegien); T. Brüning (Thomas); B. Burwinkel (Barbara); S.S. Buys (Saundra); Q. Cai (Qiuyin); T. Caldes (Trinidad); I. Campbell (Ian); T.A. Carpenter (Adrian); J. Chang-Claude (Jenny); Choi, J.-Y. (Ji-Yeob); K.B.M. Claes (Kathleen B.M.); C. Clarke (Christine); A. Cox (Angela); S.S. Cross (Simon); K. Czene (Kamila); M.B. Daly (Mary B.); M. de La Hoya (Miguel); K. De Leeneer (Kim); P. Devilee (Peter); O. Díez (Orland); S.M. Domchek (Susan); M. Doody (Michele); C.M. Dorfling (Cecilia); T. Dörk (Thilo); I. dos Santos Silva (Isabel); M. Dumont (Martine); M. Dwek (Miriam); Dworniczak, B. (Bernd); K.M. Egan (Kathleen); U. Eilber (Ursula); Z. Einbeigi (Zakaria); B. Ejlertsen (Bent); S.D. Ellis (Steve); D. Frost (Debra); F. Lalloo (Fiona); P.A. Fasching (Peter); J.D. Figueroa (Jonine); H. Flyger (Henrik); M. Friedlander (Michael); E. Friedman (Eitan); Gambino, G. (Gaetana); Gao, Y.-T. (Yu-Tang); J. Garber (Judy); M. García-Closas (Montserrat); P.A. Gehrig (Paola A.); F. Damiola (Francesca); F. Lesueur (Fabienne); S. Mazoyer (Sylvie); D. Stoppa-Lyonnet (Dominique); Giles, G.G. (Graham G.); A.K. Godwin (Andrew K.); D. Goldgar (David); A. González-Neira (Anna); M.H. Greene (Mark H.); P. Guénel (Pascal); L. Haeberle (Lothar); C.A. Haiman (Christopher A.); Hallberg, E. (Emily); U. Hamann (Ute); T.V.O. Hansen (Thomas); S. Hart (Stewart); J.M. Hartikainen (J.); J.M. Hartman (Joost); N. Hassan (Norhashimah); S. Healey (Sue); F.B.L. Hogervorst (Frans); S. Verhoef; Hendricks, C.B. (Carolyn B.); P. Hillemanns (Peter); A. Hollestelle (Antoinette); P.J. Hulick (Peter); D. Hunter (David); E.N. Imyanitov (Evgeny); C. Isaacs (Claudine); H. Ito (Hidemi); A. Jakubowska (Anna); R. Janavicius (Ramunas); Jaworska-Bieniek, K. (Katarzyna); U.B. Jensen; E.M. John (Esther); Joly Beauparlant, C. (Charles); M. Jones (Michael); M. Kabisch (Maria); D. Kang (Daehee); Karlan, B.Y. (Beth Y.); S. Kauppila (Saila); M. Kerin (Michael); S. Khan (Sofia); E.K. Khusnutdinova (Elza); J.A. Knight (Julia); I. Konstantopoulou (I.); P. Kraft (Peter); A. Kwong (Ava); Y. Laitman (Yael); Lambrechts, D. (Diether); C. Lazaro (Conxi); L. Le Marchand (Loic); C.N. Lee (Chuen); M.H. Lee (Min Hyuk); K.J. Lester (Kathryn); J. Li (Jingmei); A. Liljegren (Annelie); A. Lindblom (Annika); A. Lophatananon (Artitaya); J. Lubinski (Jan); P.L. Mai (Phuong); A. Mannermaa (Arto); S. Manoukian (Siranoush); S. Margolin (Sara); Marme, F. (Frederik); K. Matsuo (Keitaro); L. McGuffog (Lesley); A. Meindl (Alfons); F. Menegaux (Florence); M. Montagna (Marco); K.R. Muir (K.); A.-M. Mulligan (Anna-Marie); K.L. Nathanson (Katherine); S.L. Neuhausen (Susan); H. Nevanlinna (Heli); P. Newcomb (Polly); S. Nord (Silje); R.L. Nussbaum (Robert L.); K. Offit (Kenneth); E. Olah; O.I. Olopade (Olufunmilayo I.); C. Olswold (Curtis); A. Osorio (Ana); L. Papi (Laura); T.-W. Park-Simon; Paulsson-Karlsson, Y. (Ylva); S.T.H. Peeters (Stephanie); B. Peissel (Bernard); P. Peterlongo (Paolo); J. Peto (Julian); G. Pfeiler (Georg); C. Phelan (Catherine); Presneau, N. (Nadege); P. Radice (Paolo); N. Rahman (Nazneen); S.J. Ramus (Susan); M.U. Rashid (Muhammad); G. Rennert (Gad); K. Rhiem (Kerstin); Rudolph, A. (Anja); R. Salani (Ritu); Sangrajrang, S. (Suleeporn); E.J. Sawyer (Elinor); M.K. Schmidt (Marjanka); R.K. Schmutzler (Rita); M. Schoemaker (Minouk); P. Schürmann (Peter); C.M. Seynaeve (Caroline); C.-Y. Shen (Chen-Yang); M. Shrubsole (Martha); X.-O. Shu (Xiao-Ou); A.J. Sigurdson (Alice); C.F. Singer (Christian); S. Slager (Susan); Soucy, P. (Penny); M.C. Southey (Melissa); D. Steinemann (Doris); A.J. Swerdlow (Anthony ); C. Szabo (Csilla); Tchatchou, S. (Sandrine); P.J. Teixeira; S.-H. Teo; M.B. Terry (Mary Beth); D.C. Tessier (Daniel C.); A. Teulé (A.); M. Thomassen (Mads); L. Tihomirova (Laima); M. Tischkowitz (Marc); A.E. Toland (Amanda); N. Tung (Nadine); C. Turnbull (Clare); A.M.W. van den Ouweland (Ans); E.J. van Rensburg (Elizabeth); ven den Berg, D. (David); J. Vijai (Joseph); S. Wang-Gohrke (Shan); J.N. Weitzel (Jeffrey); A.S. Whittemore (Alice); R. Winqvist (Robert); Wong, T.Y. (Tien Y.); A.H. Wu (Anna); Yannoukakos, D. (Drakoulis); J-C. Yu (Jyh-Cherng); P.D.P. Pharoah (Paul); P. Hall (Per); G. Chenevix-Trench (Georgia); A.M. Dunning (Alison); J. Simard (Jacques); F.J. Couch (Fergus); A.C. Antoniou (Antonis C.); D.F. Easton (Douglas F.); W. Zheng (Wei)

    2016-01-01

    textabstractBackground: Multiple recent genome-wide association studies (GWAS) have identified a single nucleotide polymorphism (SNP), rs10771399, at 12p11 that is associated with breast cancer risk. Method: We performed a fine-scale mapping study of a 700 kb region including 441 genotyped and more

  20. Aviation Model: A Fine-Scale Numerical Weather Prediction System for Aviation Applications at the Hong Kong International Airport

    Directory of Open Access Journals (Sweden)

    Wai-Kin Wong

    2013-01-01

    Full Text Available The Hong Kong Observatory (HKO is planning to implement a fine-resolution Numerical Weather Prediction (NWP model for supporting the aviation weather applications at the Hong Kong International Airport (HKIA. This new NWP model system, called Aviation Model (AVM, is configured at a horizontal grid spacing of 600 m and 200 m. It is based on the WRF-ARW (Advance Research WRF model that can have sufficient computation efficiency in order to produce hourly updated forecasts up to 9 hours ahead on a future high performance computer system with theoretical peak performance of around 10 TFLOPS. AVM will be nested inside the operational mesoscale NWP model of HKO with horizontal resolution of 2 km. In this paper, initial numerical experiment results in forecast of windshear events due to seabreeze and terrain effect are discussed. The simulation of sea-breeze-related windshear is quite successful, and the headwind change observed from flight data could be reproduced in the model forecast. Some impacts of physical processes on generating the fine-scale wind circulation and development of significant convection are illustrated. The paper also discusses the limitations in the current model setup and proposes methods for the future development of AVM.

  1. Mother-offspring distances reflect sex differences in fine-scale genetic structure of eastern grey kangaroos.

    Science.gov (United States)

    King, Wendy J; Garant, Dany; Festa-Bianchet, Marco

    2015-05-01

    Natal dispersal affects life history and population biology and causes gene flow. In mammals, dispersal is usually male-biased so that females tend to be philopatric and surrounded by matrilineal kin, which may lead to preferential associations among female kin. Here we combine genetic analyses and behavioral observations to investigate spatial genetic structure and sex-biased dispersal patterns in a high-density population of mammals showing fission-fusion group dynamics. We studied eastern grey kangaroos (Macropus giganteus) over 2 years at Wilsons Promontory National Park, Australia, and found weak fine-scale genetic structure among adult females in both years but no structure among adult males. Immature male kangaroos moved away from their mothers at 18-25 months of age, while immature females remained near their mothers until older. A higher proportion of male (34%) than female (6%) subadults and young adults were observed to disperse, although median distances of detected dispersals were similar for both sexes. Adult females had overlapping ranges that were far wider than the maximum extent of spatial genetic structure found. Female kangaroos, although weakly philopatric, mostly encounter nonrelatives in fission-fusion groups at high density, and therefore kinship is unlikely to strongly affect sociality.

  2. Mother–offspring distances reflect sex differences in fine-scale genetic structure of eastern grey kangaroos

    Science.gov (United States)

    King, Wendy J; Garant, Dany; Festa-Bianchet, Marco

    2015-01-01

    Natal dispersal affects life history and population biology and causes gene flow. In mammals, dispersal is usually male-biased so that females tend to be philopatric and surrounded by matrilineal kin, which may lead to preferential associations among female kin. Here we combine genetic analyses and behavioral observations to investigate spatial genetic structure and sex-biased dispersal patterns in a high-density population of mammals showing fission–fusion group dynamics. We studied eastern grey kangaroos (Macropus giganteus) over 2 years at Wilsons Promontory National Park, Australia, and found weak fine-scale genetic structure among adult females in both years but no structure among adult males. Immature male kangaroos moved away from their mothers at 18–25 months of age, while immature females remained near their mothers until older. A higher proportion of male (34%) than female (6%) subadults and young adults were observed to disperse, although median distances of detected dispersals were similar for both sexes. Adult females had overlapping ranges that were far wider than the maximum extent of spatial genetic structure found. Female kangaroos, although weakly philopatric, mostly encounter nonrelatives in fission–fusion groups at high density, and therefore kinship is unlikely to strongly affect sociality. PMID:26045958

  3. On the diffusion mechanisms of fine-scale γ′ in an advanced Ni-based superalloy

    Directory of Open Access Journals (Sweden)

    Chen Y.

    2014-01-01

    Full Text Available Size dependent compositional variations for the ordered L12-structure gamma prime (γ′ precipitates in the commercial Ni-based superalloy RR1000 have been investigated using scanning transmission electron microscope (STEM imaging combined with energy-dispersive X-ray (EDX spectroscopy. To address the problem of quantitative compositional determination for nanoscale particles within a metal matrix we have applied a novel electrochemical method to extract individual precipitates. The use of a high-efficiency EDX detector enabled compositional measurements to be obtained for particles with diameters as small as 20 nm with acquisition times of the order of a few minutes. We have studied compositional variations across the different size families of γ′ precipitates within a microstructure generated by slow cooling. Our results demonstrate the importance of kinetic factors for determining the precipitates compositions. In particular, we provide new evidence for the role of aluminium antisite atoms on the low-temperature growth kinetics of fine scale γ′ precipitates. Our findings provide valuable structural data towards improving the accuracy of predicting the microstructural evolution in Ni-based superalloys.

  4. Cultural transmission of tool use combined with habitat specializations leads to fine-scale genetic structure in bottlenose dolphins.

    Science.gov (United States)

    Kopps, Anna M; Ackermann, Corinne Y; Sherwin, William B; Allen, Simon J; Bejder, Lars; Krützen, Michael

    2014-05-01

    Socially learned behaviours leading to genetic population structure have rarely been described outside humans. Here, we provide evidence of fine-scale genetic structure that has probably arisen based on socially transmitted behaviours in bottlenose dolphins (Tursiops sp.) in western Shark Bay, Western Australia. We argue that vertical social transmission in different habitats has led to significant geographical genetic structure of mitochondrial DNA (mtDNA) haplotypes. Dolphins with mtDNA haplotypes E or F are found predominantly in deep (more than 10 m) channel habitat, while dolphins with a third haplotype (H) are found predominantly in shallow habitat (less than 10 m), indicating a strong haplotype-habitat correlation. Some dolphins in the deep habitat engage in a foraging strategy using tools. These 'sponging' dolphins are members of one matriline, carrying haplotype E. This pattern is consistent with what had been demonstrated previously at another research site in Shark Bay, where vertical social transmission of sponging had been shown using multiple lines of evidence. Using an individual-based model, we found support that in western Shark Bay, socially transmitted specializations may have led to the observed genetic structure. The reported genetic structure appears to present an example of cultural hitchhiking of mtDNA haplotypes on socially transmitted foraging strategies, suggesting that, as in humans, genetic structure can be shaped through cultural transmission.

  5. Fine-scale planktonic habitat partitioning at a shelf-slope front revealed by a high-resolution imaging system

    Science.gov (United States)

    Greer, Adam T.; Cowen, Robert K.; Guigand, Cedric M.; Hare, Jonathan A.

    2015-02-01

    Ocean fronts represent productive regions of the ocean, but predator-prey interactions within these features are poorly understood partially due to the coarse-scale and biases of net-based sampling methods. We used the In Situ Ichthyoplankton Imaging System (ISIIS) to sample across a front near the Georges Bank shelf edge on two separate sampling days in August 2010. Salinity characterized the transition from shelf to slope water, with isopycnals sloping vertically, seaward, and shoaling at the thermocline. A frontal feature defined by the convergence of isopycnals and a surface temperature gradient was sampled inshore of the shallowest zone of the shelf-slope front. Zooplankton and larval fishes were abundant on the shelf side of the front and displayed taxon-dependent depth distributions but were rare in the slope waters. Supervised automated particle counting showed small particles with high solidity, verified to be zooplankton (copepods and appendicularians), aggregating near surface above the front. Salps were most abundant in zones of intermediate chlorophyll-a fluorescence, distinctly separate from high abundances of other grazers and found almost exclusively in colonial form (97.5%). Distributions of gelatinous zooplankton differed among taxa but tended to follow isopycnals. Fine-scale sampling revealed distinct habitat partitioning of various planktonic taxa, resulting from a balance of physical and biological drivers in relation to the front.

  6. Local topography shapes fine-scale spatial genetic structure in the Arkansas Valley evening primrose, Oenothera harringtonii (Onagraceae).

    Science.gov (United States)

    Rhodes, Matthew K; Fant, Jeremie B; Skogen, Krissa A

    2014-01-01

    Identifying factors that shape the spatial distribution of genetic variation is crucial to understanding many population- and landscape-level processes. In this study, we explore fine-scale spatial genetic structure in Oenothera harringtonii (Onagraceae), an insect-pollinated, gravity-dispersed herb endemic to the grasslands of south-central and southeastern Colorado, USA. We genotyped 315 individuals with 11 microsatellite markers and utilized a combination of spatial autocorrelation analyses and landscape genetic models to relate life history traits and landscape features to dispersal processes. Spatial genetic structure was consistent with theoretical expectations of isolation by distance, but this pattern was weak (Sp = 0.00374). Anisotropic analyses indicated that spatial genetic structure was markedly directional, in this case consistent with increased dispersal along prominent slopes. Landscape genetic models subsequently confirmed that spatial genetic variation was significantly influenced by local topographic heterogeneity, specifically that geographic distance, elevation and aspect were important predictors of spatial genetic structure. Among these variables, geographic distance was ~68% more important than elevation in describing spatial genetic variation, and elevation was ~42% more important than aspect after removing the effect of geographic distance. From these results, we infer a mechanism of hydrochorous seed dispersal along major drainages aided by seasonal monsoon rains. Our findings suggest that landscape features may shape microevolutionary processes at much finer spatial scales than typically considered, and stress the importance of considering how particular dispersal vectors are influenced by their environmental context.

  7. Fine-scale habitat preference of green sturgeon (Acipenser medirostris) within three spawning locations in the Sacramento River, California

    Science.gov (United States)

    Wyman, Megan T.; Thomas, Michael J.; McDonald, Richard R.; Hearn, Alexander R.; Battleson, Ryan D.; Chapman, Eric D.; Kinzel, Paul J.; Minear, J. Tobey; Mora, Ethan A.; Nelson, Jonathan M.; Pagel, Matthew D.; Klimley, A. Peter

    2017-01-01

    Vast sections of the Sacramento River have been listed as critical habitat by the National Marine Fisheries Service for green sturgeon spawning (Acipenser medirostris), yet spawning is known to occur at only a few specific locations. This study reveals the range of physical habitat variables selected by adult green sturgeon during their spawning period. We integrated fine-scale fish positions, physical habitat characteristics, discharge, bathymetry, and simulated velocity and depth using a 2-dimensional hydraulic model (FaSTMECH). The objective was to create habitat suitability curves for depth, velocity, and substrate type within three known spawning locations over two years. An overall cumulative habitat suitability score was calculated that averaged the depth, velocity, and substrate scores over all fish, sites, and years. A weighted usable area (WUA) index was calculated throughout the sampling periods for each of the three sites. Cumulative results indicate that the microhabitat characteristics most preferred by green sturgeon in these three spawning locations were velocities between 1.0-1.1 m/s, depths of 8-9 m, and gravel and sand substrate. This study provides guidance for those who may in the future want to increase spawning habitat for green sturgeon within the Sacramento River.

  8. Fine-scale population structure of Malays in Peninsular Malaysia and Singapore and implications for association studies.

    Science.gov (United States)

    Hoh, Boon-Peng; Deng, Lian; Julia-Ashazila, Mat Jusoh; Zuraihan, Zakaria; Nur-Hasnah, Ma'amor; Nur-Shafawati, Ab Rajab; Hatin, Wan Isa; Endom, Ismail; Zilfalil, Bin Alwi; Khalid, Yusoff; Xu, Shuhua

    2015-07-22

    Fine scale population structure of Malays - the major population in Malaysia, has not been well studied. This may have important implications for both evolutionary and medical studies. Here, we investigated the population sub-structure of Malay involving 431 samples collected from all states from peninsular Malaysia and Singapore. We identified two major clusters of individuals corresponding to the north and south peninsular Malaysia. On an even finer scale, the genetic coordinates of the geographical Malay populations are in correlation with the latitudes (R(2) = 0.3925; P = 0.029). This finding is further supported by the pairwise FST of Malay sub-populations, of which the north and south regions showed the highest differentiation (FST [North-south] = 0.0011). The collective findings therefore suggest that population sub-structure of Malays are more heterogenous than previously expected even within a small geographical region, possibly due to factors like different genetic origins, geographical isolation, could result in spurious association as demonstrated in our analysis. We suggest that cautions should be taken during the stage of study design or interpreting the association signals in disease mapping studies which are expected to be conducted in Malay population in the near future.

  9. Impact of soil matric potential on the fine-scale spatial distribution and activity of specific microbial degrader communities.

    Science.gov (United States)

    Monard, Cécile; Mchergui, Chokri; Nunan, Naoise; Martin-Laurent, Fabrice; Vieublé-Gonod, Laure

    2012-09-01

    The impact of the soil matric potential on the relationship between the relative abundance of degraders and their activity and on the spatial distribution of both at fine scales was determined to understand the role of environmental conditions in the degradation of organic substrates. The mineralization of (13) C-glucose and (13) C-2,4-dichlorophenoxyacetic acid (2,4-D) was measured at different matric potentials (-0.001, -0.01 and -0.316 MPa) in 6 × 6 × 6 mm(3) cubes excised from soil cores. At the end of the incubation, total bacterial and 2,4-D degrader abundances were determined by quantifying the 16S rRNA and the tfdA genes, respectively. The mineralization of 2,4-D was more sensitive to changes in matric potential than was that of glucose. The amount and spatial structure of 2,4-D mineralization decreased with matric potential, whilst the spatial variability increased. On the other hand, the spatial variation of glucose mineralization was less affected by changes in matric potential. The relationship between the relative abundance of 2,4-D degraders and 2,4-D mineralization was significantly affected by matric potential: the relative abundance of tfdA needed to be higher to reach a given level of 2,4-D mineralization in dryer than in moister conditions. The data show how microbial interactions with their microhabitat can have an impact on soil processes at larger scales.

  10. Sampling strategy for wild soybean (Glycine soja) populations based on their genetic diversity and fine-scale spatial genetic structure

    Institute of Scientific and Technical Information of China (English)

    ZHU Weiyue; ZHOU Taoying; ZHONG Ming; LU Baorong

    2007-01-01

    A total of 892 individuals sampled from a wild soybean population in a natural reserve near the Yellow River estuary located in Kenli of Shandong Province (China) were investigated.Seventeen SSR (simple sequence repeat) primer pairs from cultivated soybeans were used to estimate the genetic diversity of the population and its variation pattern versus changes of the sample size (sub-samples),in addition to investigating the fine-scale spatial genetic structure within the population.The results showed relatively high genetic diversity of the population with the mean value of allele number (A) being 2.88,expected heterozygosity (He) 0.431,Shannon diversity index (/) 0.699,and percentage of polymorphic loci (P) 100%.Sub-samples of different sizes (ten groups) were randomly drawn from the population and their genetic diversity was calculated by computer simulation.The regression model of the four diversity indexes with the change of sample sizes was computed.As a result,27-52 individuals can reach 95% of total genetic variability of the population.Spatial autocorrelation analysis revealed that the genetic patch size of this wild soybean population is about 18 m.The study provided a scientific basis for the sampling strategy of wild soybean populations.

  11. Color-Biased Dispersal Inferred by Fine-Scale Genetic Spatial Autocorrelation in a Color Polymorphic Salamander.

    Science.gov (United States)

    Grant, Alexa H; Liebgold, Eric B

    2017-07-01

    Behavioral traits can be influenced by predation rates of color morphs, potentially leading to reduced boldness or increased escape behaviors in one color morph. The red-backed salamander, Plethodon cinereus, is a small terrestrial salamander whose color morphs have different diets and select different microhabitats, but little is known about potential differences in dispersal behaviors. We used fine-scale genetic spatial autocorrelation to examine 122 P. cinereus in a color-polymorphic population at 10 microsatellite loci in order to generate estimates of spatial genetic structure for each color morph. Differences in spatial genetic structure have been used extensively to infer within-population sex-biased dispersal but have never been used to test for dispersal differences between other groups within populations such as color morphs. We found evidence for color-biased dispersal, but not sex-biased dispersal. Striped salamanders had significant positive genetic structure in the shortest distance classes indicating philopatry. In contrast, unstriped salamanders showed a lack of spatial genetic structure at shorter distances and higher than expected genetic similarity at further distances, as expected if they are dispersing from their natal site. These results show that genetic methods typically used for sex-biased dispersal can be used to investigate differences in dispersal between morphs that vary discretely in polymorphic populations, such as color morphs. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Fine-scale features on the sea surface in SAR satellite imagery – Part 1: Simultaneous in-situ measurements

    Directory of Open Access Journals (Sweden)

    S. Brusch

    2012-09-01

    Full Text Available This work is aimed at identifying the origin of fine-scale features on the sea surface in synthetic aperture radar (SAR imagery with the help of in-situ measurements as well as numerical models (presented in a companion paper. We are interested in natural and artificial features starting from the horizontal scale of the upper ocean mixed layer, around 30–50 m. These features are often associated with three-dimensional upper ocean dynamics. We have conducted a number of studies involving in-situ observations in the Straits of Florida during SAR satellite overpass. The data include examples of sharp frontal interfaces, wakes of surface ships, internal wave signatures, as well as slicks of artificial and natural origin. Atmospheric processes, such as squall lines and rain cells, produced prominent signatures on the sea surface. This data has allowed us to test an approach for distinguishing between natural and artificial features and atmospheric influences in SAR images that is based on a co-polarized phase difference filter.

  13. Adaptive modelling of long-distance wave propagation and fine-scale flooding during the Tohoku tsunami

    Directory of Open Access Journals (Sweden)

    S. Popinet

    2012-04-01

    Full Text Available The 11 March 2011 Tohoku tsunami is simulated using the quadtree-adaptive Saint-Venant solver implemented within the Gerris Flow Solver. The spatial resolution is adapted dynamically from 250 m in flooded areas up to 250 km for the areas at rest. Wave fronts are tracked at a resolution of 1.8 km in deep water. The simulation domain extends over 73° of both latitude and longitude and covers a significant part of the north-west Pacific. The initial wave elevation is obtained from a source model derived using seismic data only. Accurate long-distance wave prediction is demonstrated through comparison with DART buoys timeseries and GLOSS tide gauges records. The model also accurately predicts fine-scale flooding compared to both satellite and survey data. Adaptive mesh refinement leads to orders-of-magnitude gains in computational efficiency compared to non-adaptive methods. The study confirms that consistent source models for tsunami initiation can be obtained from seismic data only. However, while the observed extreme wave elevations are reproduced by the model, they are located further south than in the surveyed data. Comparisons with inshore wave buoys data indicate that this may be due to an incomplete understanding of the local wave generation mechanisms.

  14. Phylogenetic analysis, genetic diversity and relationships between the recently segregated species of Corynandra and Cleoserrata from the genus Cleome using DNA barcoding and molecular markers.

    Science.gov (United States)

    Tamboli, Asif Shabodin; Patil, Swapnil Mahadeo; Gholave, Avinash Ramchandra; Kadam, Suhas Kishor; Kotibhaskar, Shreya Vijaykumar; Yadav, Shrirang Ramchandra; Govindwar, Sanjay Prabhu

    2016-01-01

    Cleome is the largest genus in the family Cleomaceae and it is known for its various medicinal properties. Recently, some species from the Cleome genus (Cleome viscosa, Cleome chelidonii, Cleome felina and Cleome speciosa) are split into genera Corynandra (Corynandra viscosa, Corynandra chelidonii, Corynandra felina), and Cleoserrata (Cleoserrata speciosa). The objective of this study was to obtain DNA barcodes for these species for their accurate identification and determining phylogenetic relationships. Out of 10 screened barcoding regions, rbcL, matK and ITS1 regions showed higher PCR efficiency and sequencing success. This study added matK, rbcL and ITS1 barcodes for the identification of Corynandra chelidonii, Corynandra felina, Cleome simplicifolia and Cleome aspera species in existing barcode data. Corynandra chelidonii and Corynandra felina species belong to the Corynandra genus, but they are not grouped with the Corynandra viscosa species, however clustered with the Cleome species. Molecular marker analysis showed 100% polymorphism among the studied plant samples. Diversity indices for molecular markers were ranged from He=0.1115-0.1714 and I=0.2268-0.2700, which indicates a significant amount of genetic diversity among studied species. Discrimination of the Cleome and Corynandra species from Cleoserrata speciosa was obtained by two RAPD primers (OPA-4 and RAPD-17) and two ISSR primers (ISSR-1 and ISSR-2). RAPD and ISSR markers are useful for the genetic characterization of these studied species. The present investigation will be helpful to understand the relationships of Cleome lineages with Corynandra and Cleoserrata species.

  15. Disturbances can control fine-scale pedodiversity in old-growth forest: is the soil evolution theory disturbed as well?

    Directory of Open Access Journals (Sweden)

    P. Šamonil

    2014-04-01

    Full Text Available Biota–soil interaction in natural ecosystems is an area of considerable research. Our hypothesis is that individual trees play a significant role through biomechanical and biochemical disturbances in soil formation in temperate forest resulting in complex spatial pattern of disturbance regimes and a close relationship between disturbance histories and soil units. In Žofínský Prales (Czech Republic – the fourth oldest, continuously protected reserve in Europe and the only SIGEO site in continental Europe – in time and space we compared extensive dendrochronological, soil and pit-mound microtopography data on an area of 42.01 ha collected in 2008–2012. The datasets differ in terms of information complexity and length of memory. Tree cores contain complex information about disturbance history of the past 350 years, footprints of the specific tree uprooting disturbance can persist 1700 years, and soils representing extensive composite phenotype have been developing for at least the entire postglacial period (10 500 years. On average, 6.18–13.41% of the canopy was disturbed on individual soil units per decade. Even though the "backbone" of key events in the development of the forest ecosystem remained the same (e.g. the 1870s, 1880s and 1980s, the internal structure of disturbance history often differed among soil units; the most exceptional were Gleysols and Histosols, where important feedback from soil to trees was expected. However characteristics of treethrow dynamics as well as frequencies of stronger releases in core series significantly differed also along a gradient of terrestrial soil weathering and leaching (Haplic Cambisols – Dystric Cambisols – Entic Podzols – Albic Podzols. Results suggest the existence of several disturbance regimes within the forest controlling fine-scale pedodiversity.

  16. Fine-Scale Community Structure Analysis of ANME in Nyegga Sediments with High and Low Methane Flux.

    Science.gov (United States)

    Roalkvam, Irene; Dahle, Håkon; Chen, Yifeng; Jørgensen, Steffen Leth; Haflidason, Haflidi; Steen, Ida Helene

    2012-01-01

    To obtain knowledge on how regional variations in methane seepage rates influence the stratification, abundance, and diversity of anaerobic methanotrophs (ANME), we analyzed the vertical microbial stratification in a gravity core from a methane micro-seeping area at Nyegga by using 454-pyrosequencing of 16S rRNA gene tagged amplicons and quantitative PCR. These data were compared with previously obtained data from the more active G11 pockmark, characterized by higher methane flux. A down core stratification and high relative abundance of ANME were observed in both cores, with transition from an ANME-2a/b dominated community in low-sulfide and low methane horizons to ANME-1 dominance in horizons near the sulfate-methane transition zone. The stratification was over a wider spatial region and at greater depth in the core with lower methane flux, and the total 16S rRNA copy numbers were two orders of magnitude lower than in the sediments at G11 pockmark. A fine-scale view into the ANME communities at each location was achieved through operational taxonomical units (OTU) clustering of ANME-affiliated sequences. The majority of ANME-1 sequences from both sampling sites clustered within one OTU, while ANME-2a/b sequences were represented in unique OTUs. We suggest that free-living ANME-1 is the most abundant taxon in Nyegga cold seeps, and also the main consumer of methane. The observation of specific ANME-2a/b OTUs at each location could reflect that organisms within this clade are adapted to different geochemical settings, perhaps due to differences in methane affinity. Given that the ANME-2a/b population could be sustained in less active seepage areas, this subgroup could be potential seed populations in newly developed methane-enriched environments.

  17. Spatial spin-up of fine scales in a regional climate model simulation driven by low-resolution boundary conditions

    Science.gov (United States)

    Matte, Dominic; Laprise, René; Thériault, Julie M.; Lucas-Picher, Philippe

    2017-07-01

    In regional climate modelling, it is well known that domains should be neither too large to avoid a large departure from the driving data, nor too small to provide a sufficient distance from the lateral inflow boundary to allow the full development of the small-scale (SS) features permitted by the finer resolution. Although most practitioners of dynamical downscaling are well aware that the jump of resolution between the lateral boundary condition (LBC) driving data and the nested regional climate model affects the simulated climate, this issue has not been fully investigated. In principle, as the jump of resolution becomes larger, the region of interest in the limited-area domain should be located further away from the lateral inflow boundary to allow the full development of the SS features. A careless choice of domain might result in a suboptimal use of the full finer resolution potential to develop fine-scale features. To address this issue, regional climate model (RCM) simulations using various resolution driving data are compared following the perfect-prognostic Big-Brother protocol. Several experiments were carried out to evaluate the width of the spin-up region (i.e. the distance between the lateral inflow boundary and the domain of interest required for the full development of SS transient eddies) as a function of the RCM and LBC resolutions, as well as the resolution jump. The spin-up distance turns out to be a function of the LBC resolution only, independent of the RCM resolution. When varying the RCM resolution for a given resolution jump, it is found that the spin-up distance corresponds to a fixed number of RCM grid points that is a function of resolution jump only. These findings can serve a useful purpose to guide the choice of domain and RCM configuration for an optimal development of the small scales allowed by the increased resolution of the nested model.

  18. Human Social Behavior and Demography Drive Patterns of Fine-Scale Dengue Transmission in Endemic Areas of Colombia.

    Directory of Open Access Journals (Sweden)

    Harish Padmanabha

    Full Text Available Dengue is known to transmit between humans and A. aegypti mosquitoes living in neighboring houses. Although transmission is thought to be highly heterogeneous in both space and time, little is known about the patterns and drivers of transmission in groups of houses in endemic settings. We carried out surveys of PCR positivity in children residing in 2-block patches of highly endemic cities of Colombia. We found high levels of heterogeneity in PCR positivity, varying from less than 30% in 8 of the 10 patches to 56 and 96%, with the latter patch containing 22 children simultaneously PCR positive (PCR22 for DEN2. We then used an agent-based model to assess the likely eco-epidemiological context of this observation. Our model, simulating daily dengue dynamics over a 20 year period in a single two block patch, suggests that the observed heterogeneity most likely derived from variation in the density of susceptible people. Two aspects of human adaptive behavior were critical to determining this density: external social relationships favoring viral introduction (by susceptible residents or infectious visitors and immigration of households from non-endemic areas. External social relationships generating frequent viral introduction constituted a particularly strong constraint on susceptible densities, thereby limiting the potential for explosive outbreaks and dampening the impact of heightened vectorial capacity. Dengue transmission can be highly explosive locally, even in neighborhoods with significant immunity in the human population. Variation among neighborhoods in the density of local social networks and rural-to-urban migration is likely to produce significant fine-scale heterogeneity in dengue dynamics, constraining or amplifying the impacts of changes in mosquito populations and cross immunity between serotypes.

  19. Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems.

    Directory of Open Access Journals (Sweden)

    Florian Holon

    Full Text Available Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m. It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures

  20. Spatial spin-up of fine scales in a regional climate model simulation driven by low-resolution boundary conditions

    Science.gov (United States)

    Matte, Dominic; Laprise, René; Thériault, Julie M.; Lucas-Picher, Philippe

    2016-09-01

    In regional climate modelling, it is well known that domains should be neither too large to avoid a large departure from the driving data, nor too small to provide a sufficient distance from the lateral inflow boundary to allow the full development of the small-scale (SS) features permitted by the finer resolution. Although most practitioners of dynamical downscaling are well aware that the jump of resolution between the lateral boundary condition (LBC) driving data and the nested regional climate model affects the simulated climate, this issue has not been fully investigated. In principle, as the jump of resolution becomes larger, the region of interest in the limited-area domain should be located further away from the lateral inflow boundary to allow the full development of the SS features. A careless choice of domain might result in a suboptimal use of the full finer resolution potential to develop fine-scale features. To address this issue, regional climate model (RCM) simulations using various resolution driving data are compared following the perfect-prognostic Big-Brother protocol. Several experiments were carried out to evaluate the width of the spin-up region (i.e. the distance between the lateral inflow boundary and the domain of interest required for the full development of SS transient eddies) as a function of the RCM and LBC resolutions, as well as the resolution jump. The spin-up distance turns out to be a function of the LBC resolution only, independent of the RCM resolution. When varying the RCM resolution for a given resolution jump, it is found that the spin-up distance corresponds to a fixed number of RCM grid points that is a function of resolution jump only. These findings can serve a useful purpose to guide the choice of domain and RCM configuration for an optimal development of the small scales allowed by the increased resolution of the nested model.

  1. Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems

    Science.gov (United States)

    Holon, Florian; Mouquet, Nicolas; Boissery, Pierre; Bouchoucha, Marc; Delaruelle, Gwenaelle; Tribot, Anne-Sophie; Deter, Julie

    2015-01-01

    Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant

  2. Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems.

    Science.gov (United States)

    Holon, Florian; Mouquet, Nicolas; Boissery, Pierre; Bouchoucha, Marc; Delaruelle, Gwenaelle; Tribot, Anne-Sophie; Deter, Julie

    2015-01-01

    Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant

  3. Fine-scale community structure analysis of ANME in Nyegga sediments with high and low methane flux

    Directory of Open Access Journals (Sweden)

    Irene eRoalkvam

    2012-06-01

    Full Text Available To obtain knowledge on how regional variations in methane seepage rates influence the stratification, abundance and diversity of anaerobic methanotrophs (ANME we analyzed the vertical microbial stratification in a gravity core from a methane micro-seeping area at Nyegga by using 454-pyrosequencing of 16S rRNA gene tagged amplicons and quantitative PCR. The results were compared with previously obtained data from the more active G11 pockmark, characterized by higher methane flux. A downcore stratification and high relative abundance of ANME was observed in both cores, with transition from an ANME-2a/b dominated community in low-sulfide and low-methane horizons to ANME-1 dominance in horizons near the sulfate methane transition zone (SMTZ. The stratification was over a wider spatial region and at greater depth in the core with lower methane flux, and the total 16S rRNA copy numbers were two orders of magnitude lower than in the sediments at G11 pockmark. A fine-scale view into the ANME communities at each location was achieved through OTU clustering of ANME-affiliated sequences. The majority of ANME-1 sequences from both sampling sites clustered within one OTU, while ANME-2a/b sequences were represented in unique OTUs. We suggest that free living ANME-1 is the most abundant taxon in Nyegga cold seeps, and also the main consumer of methane. The specific ANME-2a/b ecotypes could reflect adaptations to the geochemical composition at each location, with different affinities to methane. Given that the ANME-2a/b population could be sustained in less active seepage areas, this subgroup could be potential seed populations in newly developed methane-enriched environments.

  4. Commentary: Genger Segregation in Childhood.

    Science.gov (United States)

    Maccoby, Eleanor E.

    1994-01-01

    Provides an overview of the preceding articles in this journal issue. Considers the timing of gender segregation, compatibility between play styles and gender segregation, possible physiological processes underlying gender segregation in play, children's cognitive knowledge about gender, and the consequences of gender segregation. (BAC)

  5. Sexual segregation in foraging giraffe

    Science.gov (United States)

    Mramba, Rosemary Peter; Mahenya, Obeid; Siyaya, Annetjie; Mathisen, Karen Marie; Andreassen, Harry Peter; Skarpe, Christina

    2017-02-01

    Sexual segregation in giraffe is known to vary between savannas. In this study, we compared sexual segregation in giraffe in one nutrient-rich savanna, the Serengeti National Park, one nutrient-poor, Mikumi National Park, and one medium rich savanna, Arusha National Park, (from here on referred to just by name) based on effects of sexual size dimorphism and related hypotheses. Data were collected in the wet and dry seasons, by driving road transects and making visual observations of browsing giraffe. Additional data were collected from literature (plant chemistry; mammal communities). There was a noticeable difference in browsing by females and males and in browsing between the three savannas. Females browsed a higher diversity of tree species in Serengeti whereas males browsed a higher diversity in Arusha, while the diversity of species browsed in Mikumi was high and about the same in both sexes. Females selected for high concentrations of nitrogen and low concentrations of tannins and phenolics compared to males in Serengeti but selection in Mikumi was more complex. Males browsed higher in the canopy than females in all sites, but the browsing height was generally higher in Serengeti than Mikumi and Arusha. Season had an effect on the browsing height independent of sex in Mikumi, where giraffes browsed higher in the dry season compared to the wet season. Males spent more time browsing per tree compared to females in all three sites; however, browsing time in Mikumi was also affected by season, where giraffes had longer browsing bouts in the wet season compared to the dry season. We suggest that sexual differences in forage requirement and in foraging interacts with differences in tree chemistry and in competing herbivore communities between nutrient rich and nutrient poor savanna in shaping the sexual segregation.

  6. Understanding Segregation Processes

    Science.gov (United States)

    Bruch, Elizabeth

    There is growing consensus that living in neighborhoods of concentrated poverty increases the likelihood of social problems such as teenage parenthood, drug and alcohol use, crime victimization, and chronic unemployment. Neighborhood inequality is also implicated in studies of enduring race/ethnic health disparities, and there are recent moves to broaden the definition of health care policy to policies targeting social inequality (Mechanic 2007). Residential segregation affects health outcomes in several different ways. First, income, education, and occupation are all strongly related to health (Adler and Newman 2002). Segregation is a key mechanism through which socioeconomic inequality is perpetuated and reinforced, as it hinders the upward mobility of disadvantaged groups by limiting their educational and employment opportunities. Second, segregation increases minority exposure to unhealthy neighborhood environments. Residential segregation creates areas with concentrated poverty and unemployment, both of which are key factors that predict violence and create racial differences in homicide (Samson and Wilson 1995). Neighborhood characteristics, such as exposure to environmental hazards, fear of violence, and access to grocery stores, affect health risks and health behaviors (Cheadle et al. 1991). Tobacco and alcohol industries also advertise their products disproportionately in poor, minority areas (Moore, Williams, and Qualls 1996). Finally, residential segregation leads to inequalitie in health care resources, which contributes to disparities in quality of treatment (Smedley, Stith, and Nelson 2002).

  7. Stabilization of species coexistence in spatial models through the aggregation-segregation effect generated by local dispersal and nonspecific local interactions.

    Science.gov (United States)

    Detto, Matteo; Muller-Landau, Helene C

    2016-12-01

    Spatial interactions are widely acknowledged to play a significant role in sustaining diversity in ecological communities. However, theoretical work on this topic has focused on how spatial processes affect coexistence of species that differ in their strategies, with less attention to how spatial processes matter when competitors are equivalent. Furthermore, though it is recognized that models with local dispersal and local competition may sustain higher diversities of equivalent competitors than models in which these are not both localized, there is debate as to whether this reflects merely equalizing effects or whether there is also a stabilizing component. In this study, we explore how dispersal limitation and nonspecific local competition influence the outcome of species coexistence in communities driven by stochastic drift. We demonstrate that space alone acts as a stabilizing factor in a continuous space model with local dispersal and competition, as individuals of rare species on average experience lower total neighborhood densities, causing per capita reproductive rates to decrease systematically with increasing abundance. These effects prolong time to extinction in a closed system and enhance species diversity in an open system with constant immigration. Fundamentally, these stabilizing effects are obtained when dispersal limitation interacts with local competition to generate fluctuations in population growth rates. Thus this effect can be considered a fluctuating mechanism similar to spatial or temporal storage effects, but generated purely endogenously without requiring any exogenous environmental variability or species dissimilarities.

  8. Research on the Fine-Scale Spatial Uniformity of Natural Rainfall and Rainfall from a Rainfall Simulator with a Rotary Platform (RSRP)

    OpenAIRE

    Bo Liu; Xiaolei Wang; Lihua Shi; Xichuan Liu; Zhaojing Kang; Zhentao Chen

    2017-01-01

    Abstract: The accurate production of a rainfall environment similar to natural rainfall by a rainfall simulator (RS) is a crucial and challenging task in rainfall instrument testing or calibration. Although the spatial uniformity of rainfall accumulation is a key parameter of an RS, the spatial uniformity comparison between simulated rainfall and natural rainfall, and the spatial uniformity improvements for an RS are scant in the literature. In this study, a fine-scale natural rainfall experi...

  9. SYSTEMATIC MOTION OF FINE-SCALE JETS AND SUCCESSIVE RECONNECTION IN SOLAR CHROMOSPHERIC ANEMONE JET OBSERVED WITH THE SOLAR OPTICAL TELESCOPE/HINODE

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K. A. P.; Nishida, K.; Shibata, K. [Kwasan and Hida Observatories, Graduate School of Science, Kyoto University, Yamashina, Kyoto 607-8471 (Japan); Isobe, H., E-mail: singh@kwasan.kyoto-u.ac.jp [Unit for Synergetic Study for Space, Kyoto University, Yamashina, Kyoto 607-8471 (Japan)

    2012-11-20

    The Solar Optical Telescope (SOT) on board Hinode allows observations with high spatiotemporal resolution and stable image quality. A {lambda}-shaped chromospheric anemone jet was observed in high resolution with SOT/Hinode. We found that several fine-scale jets were launched from one end of the footpoint to the other. These fine-scale jets ({approx}1.5-2.5 Mm) gradually move from one end of the footpoint to the other and finally merge into a single jet. This process occurs recurrently, and as time progresses the jet activity becomes more and more violent. The time evolution of the region below the jet in Ca II H filtergram images taken with SOT shows that various parts (or knots) appear at different positions. These bright knots gradually merge into each other during the maximum phase. The systematic motion of the fine-scale jets is observed when different knots merge into each other. Such morphology would arise due to the emergence of a three-dimensional twisted flux rope in which the axial component (or the guide field) appears in the later stages of the flux rope emergence. The partial appearance of the knots could be due to the azimuthal magnetic field that appears during the early stage of the flux rope emergence. If the guide field is strong and reconnection occurs between the emerging flux rope and an ambient magnetic field, this could explain the typical feature of systematic motion in chromospheric anemone jets.

  10. Measuring Inequality and Segregation

    CERN Document Server

    Roberto, Elizabeth

    2015-01-01

    In this paper, I introduce the Divergence Index, a conceptually intuitive and methodologically rigorous measure of inequality and segregation. The index measures the difference between a distribution of interest and another empirical, theoretical, or normative distribution. The Divergence Index provides flexibility in specifying a theoretically meaningful basis for evaluating inequality. It evaluates how surprising an empirical distribution is given a theoretical distribution that represents equality. I demonstrate the unique features of the new measure, as well as deriving its mathematical equivalence with Theil's Inequality Index and the Information Theory Index. I compare the dynamics of the measures using simulated data, and an empirical analysis of racial residential segregation in the Detroit, MI, metro area. The Information Theory Index has become the gold standard for decomposition analyses of segregation. I show that although the Information Theory Index can be decomposed for subareas, it is misleadi...

  11. A Question of Segregation

    DEFF Research Database (Denmark)

    Quedas, Fátima; Ponte, João; Trindade, Carlos

    2016-01-01

    than 40 per cent of breads were indeed over the labelling threshold, and should be labelled. This includes GM maize that is not cultivated in the EU and enters the supply chain via international trade. We conclude that the realisation of coexistence and segregation requires involvement of the full...

  12. Plasmid segregation mechanisms

    DEFF Research Database (Denmark)

    Ebersbach, Gitte; Gerdes, Kenn; Charbon, Gitte Ebersbach

    2005-01-01

    Bacterial plasmids encode partitioning (par) loci that ensure ordered plasmid segregation prior to cell division. par loci come in two types: those that encode actin-like ATPases and those that encode deviant Walker-type ATPases. ParM, the actin-like ATPase of plasmid R1, forms dynamic filaments ...

  13. Thermoregulation and microhabitat use in mountain butterflies of the genus Erebia: importance of fine-scale habitat heterogeneity.

    Science.gov (United States)

    Kleckova, Irena; Konvicka, Martin; Klecka, Jan

    2014-04-01

    Mountain butterflies have evolved efficient thermoregulation strategies enabling their survival in marginal conditions with short flight season and unstable weather. Understanding the importance of their behavioural thermoregulation by habitat use can provide novel information for predicting the fate of alpine Lepidoptera and other insects under ongoing climate change. We studied the link between microhabitat use and thermoregulation in adults of seven species of a butterfly genus Erebia co-occurring in the Austrian Alps. We captured individuals in the field and measured their body temperature in relation to microhabitat and air temperature. We asked whether closely related species regulate their body temperature differently, and if so, what is the effect of behaviour, species traits and individual traits on body to air and body to microhabitat temperature differences. Co-occurring species differed in mean body temperature. These differences were driven by active microhabitat selection by individuals and also by species-specific habitat preferences. Species inhabiting grasslands and rocks utilised warmer microclimates to maintain higher body temperature than woodland species. Under low air temperatures, species of rocky habitats heated up more effectively than species of grasslands and woodlands which allowed them to stay active in colder weather. Species morphology and individual traits play rather minor roles in the thermoregulatory differences; although large species and young individuals maintained higher body temperature. We conclude that diverse microhabitat conditions at small spatial scales probably contribute to sympatric occurrence of closely related species with different thermal demands and that preserving heterogeneous conditions in alpine landscapes might mitigate detrimental consequences of predicted climate change. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Fine-scale biogeography: tidal elevation strongly affects population genetic structure and demographic history in intertidal fishes

    Directory of Open Access Journals (Sweden)

    Sophie von der Heyden

    2013-04-01

    Full Text Available Numerous studies have demonstrated population genetic structuring in marine species, yet few have investigated the effect of vertical zonation on gene flow and population structure. Here we use three sympatric, closely related clinid species, Clinus cottoides, C. superciliosus and Muraenoclinus dorsalis, to test whether zonation on South African intertidal rocky shores affects phylogeographic patterns. We show that the high‐shore restricted species has reduced gene flow and considerably higher Fst values (Fst = 0.9 than the mid‐ and low‐shore species (Fst

  15. Why do polygynous ungulates segregate in space? Testing the activity-budget hypothesis in soay sheep

    OpenAIRE

    2007-01-01

    Sexual segregation is the behavior in which animals of different sex in a species live in separate groups outside the mating season. Recently a new concept, namely, the >activity-budget hypothesis,> has claimed to be the ultimate explanation of this behavior. The new hypothesis explains not only sexual segregation, but also segregation between animals of different size within sex (i.e., social segregation). The hypothesis states that the activity patterns of animals will differ when big diffe...

  16. Fine-Scale Mapping by Spatial Risk Distribution Modeling for Regional Malaria Endemicity and Its Implications under the Low-to-Moderate Transmission Setting in Western Cambodia.

    Directory of Open Access Journals (Sweden)

    Suguru Okami

    Full Text Available The disease burden of malaria has decreased as malaria elimination efforts progress. The mapping approach that uses spatial risk distribution modeling needs some adjustment and reinvestigation in accordance with situational changes. Here we applied a mathematical modeling approach for standardized morbidity ratio (SMR calculated by annual parasite incidence using routinely aggregated surveillance reports, environmental data such as remote sensing data, and non-environmental anthropogenic data to create fine-scale spatial risk distribution maps of western Cambodia. Furthermore, we incorporated a combination of containment status indicators into the model to demonstrate spatial heterogeneities of the relationship between containment status and risks. The explanatory model was fitted to estimate the SMR of each area (adjusted Pearson correlation coefficient R2 = 0.774; Akaike information criterion AIC = 149.423. A Bayesian modeling framework was applied to estimate the uncertainty of the model and cross-scale predictions. Fine-scale maps were created by the spatial interpolation of estimated SMRs at each village. Compared with geocoded case data, corresponding predicted values showed conformity [Spearman's rank correlation r = 0.662 in the inverse distance weighed interpolation and 0.645 in ordinal kriging (95% confidence intervals of 0.414-0.827 and 0.368-0.813, respectively, Welch's t-test; Not significant]. The proposed approach successfully explained regional malaria risks and fine-scale risk maps were created under low-to-moderate malaria transmission settings where reinvestigations of existing risk modeling approaches were needed. Moreover, different representations of simulated outcomes of containment status indicators for respective areas provided useful insights for tailored interventional planning, considering regional malaria endemicity.

  17. Applied Thermodynamics: Grain Boundary Segregation

    Directory of Open Access Journals (Sweden)

    Pavel Lejček

    2014-03-01

    Full Text Available Chemical composition of interfaces—free surfaces and grain boundaries—is generally described by the Langmuir–McLean segregation isotherm controlled by Gibbs energy of segregation. Various components of the Gibbs energy of segregation, the standard and the excess ones as well as other thermodynamic state functions—enthalpy, entropy and volume—of interfacial segregation are derived and their physical meaning is elucidated. The importance of the thermodynamic state functions of grain boundary segregation, their dependence on volume solid solubility, mutual solute–solute interaction and pressure effect in ferrous alloys is demonstrated.

  18. Fine-scale heat flow, shallow heat sources, and decoupled circulation systems at two sea-floor hydrothermal sites, Middle Valley, northern Juan de Fuca Ridge

    Energy Technology Data Exchange (ETDEWEB)

    Stein, J.S.; Fisher, A.T. [Univ. of California, Santa Cruz, CA (United States); Langseth, M.; Jin, W.; Iturrino, G. [Lamont-Doherty Earth Observatory, Palisades, NY (United States); Davis, E. [Geological Survey of Canada, Sidney, British Columbia (Canada). Pacific Geoscience Centre

    1998-12-01

    Fine-scale heat-flow patterns at two areas of active venting in Middle Valley, a sedimented rift on the northern Juan de Fuca Ridge, provide thermal evidence of shallow hydrothermal reservoirs beneath the vent fields. The extreme variability of heat flow is explained by conductive heating immediately adjacent to vents and shallow circulation within sediments above the reservoir. This secondary circulation is hydrologically separated from the deeper system feeding the vents by a shallow conductive lid within the sediments. A similar separation of shallow and deep circulation may also occur at sediment-free ridge-crest hydrothermal environments.

  19. Sexual segregation in vertebrates: proximate and ultimate causes.

    Science.gov (United States)

    Ruckstuhl, K E

    2007-08-01

    Sexual segregation is very common in vertebrates that live in groups. In this article, I will review proximate and ultimate causes of sexual segregation in social species and in particular in ungulates in which the bulk of research on the topic has been carried out. In most social ungulate species, males and females live in separate groups outside the breeding season, sometimes using different home ranges and types of habitat. In most of these species, males are larger than females. Dimorphism in body size can lead to sexual differences in ecology and behavior making it difficult for the two sexes to stay in the same group. It is important for our better understanding of the evolution of sociality, sexual dimorphism and different mating systems to determine why sexual segregation is so widespread not only in ungulates but also in other vertebrates. In this article, I discuss the ecology of the two sexes by reviewing proximate and ultimate causes of sexual segregation. To do this, I compare a range of studies of ruminants and include explanations for social segregation as well as for habitat segregation by gender. This leads into a review and updates current knowledge of the phenomenon. Although I present a number of different hypotheses, I focus in particular on predation risk, forage selection and activity budget and discuss the social-factors hypothesis. I stress that the key in solving the enigma of sexual segregation lies in clearly separating hypotheses that try to explain social segregation and habitat segregation, as well as in including experiments or model systems. To that end, I present a preliminary study on a test of the activity-budget hypothesis in three-spine sticklebacks and explain why I believe that shoaling fish are useful for analysing the underlying processes and mechanisms that lead to sexual segregation in animals. Lastly, I argue that it is unlikely that a single factor can explain social segregation or habitat segregation but that a model

  20. Foraging segregation of two congeneric diving seabird species (common and thick-billed murres breeding on St. George Island, Bering Sea

    Directory of Open Access Journals (Sweden)

    N. Kokubun

    2015-11-01

    Full Text Available Sub-arctic environmental changes are expected to affect the ecology of marine top predators. We examined the characteristics of foraging behavior of two sympatric congeneric diving seabirds, common (Uria aalge: hereafter COMU and thick-billed (U. lomvia: hereafter TBMU murres breeding on St. George Island located in the seasonal sea-ice region of the Bering Sea. We investigated their flight duration, diel patterns of dive depth, and underwater wing strokes, along with morphology and blood stable isotopes. Acceleration-temperature-depth data loggers were attached to chick-guarding birds, and behavioral data were obtained from 7 COMU and 12 TBMU. Both species showed similar trip duration (13.21 ± 4.79 h for COMU and 10.45 ± 7.09 h for TBMU and similar diurnal patterns of diving (frequent dives to various depths in the daytime and less frequent dives to shallow depths in the nighttime. During the daytime, dive depths of COMU had two peaks in shallow (18.1 ± 6.0 m and deep (74.2 ± 8.7 m depths, while those of TBMU were 20.2 ± 7.4 m and 59.7 ± 7.9 m. COMU showed more frequent wing strokes during the bottom phase of dives (1.90 ± 0.11 s−1 than TBMU (1.66 ± 0.15 s−1. Fishes occurred with higher proportion in the bill-loads brought back to chicks in COMU (85 % than in TBMU (56 %. δ15N value of blood was significantly higher in COMU (14.47 ± 0.27 ‰ than in TBMU (13.14 ± 0.36 ‰. Relatively small wing area (0.053 ± 0.007 m2 of COMU compared to TBMU (0.067 ± 0.007 m2 may make them more agile underwater and thus enable them to target more mobile prey including larger fishes that inhabit deeper depths. These differences in foraging behavior between COMU and TBMU might explain the differences in their responses to long-term marine environmental changes.

  1. Fine-scale niche structure of Neotropical forests reflects a legacy of the Great American Biotic Interchange.

    Science.gov (United States)

    Sedio, Brian E; Paul, John R; Taylor, Charlotte M; Dick, Christopher W

    2013-01-01

    The tendency of species to retain their ancestral niches may link processes that determine community assembly with biogeographic histories that span geological time scales. Biogeographic history is likely to have had a particularly strong impact on Neotropical forests because of the influence of the Great American Biotic Interchange, which followed emergence of a land connection between North and South America ~3 Ma. Here we examine the community structure, ancestral niches and ancestral distributions of the related, hyperdiverse woody plant genera Psychotria and Palicourea (Rubiaceae) in Panama. We find that 49% of the variation in hydraulic traits, a strong determinant of community structure, is explained by species' origins in climatically distinct biogeographic regions. Niche evolution models for a regional sample of 152 species indicate that ancestral climatic niches are associated with species' habitat distributions, and hence local community structure and composition, even millions of years after dispersal into new geographic regions.

  2. Source Segregation and Collection of Source-Segregated Waste

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Matsufuji, Y.

    2011-01-01

    The Segregation of individual material fractions at the waste source and keeping the fractions separate for collection is one of the key issues in modern waste management. In most cases the waste is just kept segregated from other waste according to certain criteria that improve the possibility...... the more important it is to consider source segregation of the waste, since the amount of waste links to the possibility of obtaining manageable amounts of segregated waste with reasonable logistics as well as to the manpower that can be allocated at the source to perform source segregation of waste....... Therefore, source segregation usually makes most sense in industry, where the waste often also is more well defined and cleaner, while residential waste containing relatively small amounts of each material fraction is a bigger and much more difficult challenge. This chapter describes the main issues...

  3. The Fine-scale Structure of the Radial Electric Field in the Scrape-Off-Layer during ICRF Heating in Alcator C-Mod

    Science.gov (United States)

    Terry, J. L.; Cziegler, I.; Wukitch, S. J.; Lin, Y.; Zweben, S. J.

    2011-10-01

    By observing the radial structure in the poloidal dynamics of the SOL turbulence, we find a fine-scale radial structure in the broadband turbulence poloidal phase velocities (Vθ) with the application of ICRF power (PRF > 0.6 MW). The radial profiles are very different from typical profiles in Ohmic plasmas. Since Vθ(r) in the SOL is dominated by VExB, this structure implies a fine-scale Er profile is formed in the presence of the ICRF. The existence of such spatial structure is not predicted to be a result of the ICRF since the radial size-scale is much smaller than the fast-wave perpendicular wavelength (~10 cm). Such an Er profile may help to explain the increased impurity content observed with ICRF heating and will be important for SOL flows and transport. Using 2D Gas-Puff-Imaging we find that, in the ~3 cm region outside the separatrix, the dominant propagation direction for Vθ reverses up to 3 times. This is found beyond the region where the antenna near-fields are present; the fast wave is propagating there. While the mechanism is still unknown, it must be consistent with the following: the structure is dependent on which antenna is energized; it changes with q95 and is present when the RF frequency is 78 or 50 MHz. Supported by USDoE awards DE-FC02-99ER54512 and DE-AC02-09CH11466.

  4. Patterns of Residential Segregation.

    Directory of Open Access Journals (Sweden)

    Rémi Louf

    Full Text Available The spatial distribution of income shapes the structure and organisation of cities and its understanding has broad societal implications. Despite an abundant literature, many issues remain unclear. In particular, all definitions of segregation are implicitely tied to a single indicator, usually rely on an ambiguous definition of income classes, without any consensus on how to define neighbourhoods and to deal with the polycentric organization of large cities. In this paper, we address all these questions within a unique conceptual framework. We avoid the challenge of providing a direct definition of segregation and instead start from a definition of what segregation is not. This naturally leads to the measure of representation that is able to identify locations where categories are over- or underrepresented. From there, we provide a new measure of exposure that discriminates between situations where categories co-locate or repel one another. We then use this feature to provide an unambiguous, parameter-free method to find meaningful breaks in the income distribution, thus defining classes. Applied to the 2014 American Community Survey, we find 3 emerging classes-low, middle and higher income-out of the original 16 income categories. The higher-income households are proportionally more present in larger cities, while lower-income households are not, invalidating the idea of an increased social polarisation. Finally, using the density-and not the distance to a center which is meaningless in polycentric cities-we find that the richer class is overrepresented in high density zones, especially for larger cities. This suggests that density is a relevant factor for understanding the income structure of cities and might explain some of the differences observed between US and European cities.

  5. Fine-scale distribution patterns of Synechococcus ecological diversity in the microbial mats of Mushroom Spring, Yellowstone National Park

    DEFF Research Database (Denmark)

    Becraft, E.; Cohan, F.; Kühl, Michael

    2011-01-01

    Past analyses of sequence diversity in high-resolution protein-encoding genes have identified putative ecological species of unicellular cyanobacteria in the genus Synechococcus, which are specialized to 60°C but not 65°C in Mushroom Spring microbial mats. Because these studies were limited to on...

  6. Fine-scale responses of phytoplankton to freshwater influx in a tropical monsoonal estuary following the onset of southwest monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Pednekar, S.M.; Matondkar, S.G.P.; Gomes, H.R.; Goes, J.I.; Parab, S.G.; Kerkar, V.

    estuary; Estuarine Coast. Shelf Sci. 1 107–111. Hallegraeff G M, Anderson D M and Cembella A D 2003 Manual on harmful marine microalgae; UNESCO Publishing. Huang L, Jian W, Song X, Huang X, Liu S, Qian P, Yin K and Wu M 2004 Species diversity...

  7. A first comprehensive census of fungi in soil reveals both hyperdiversity and fine-scale niche partitioning

    Science.gov (United States)

    D. Lee Taylor; Teresa N. Hollingsworth; Jack W. McFarland; Niall J. Lennon; Chad Nusbaum; Roger W. Ruess

    2014-01-01

    Fungi play key roles in ecosystems as mutualists, pathogens, and decomposers. Current estimates of global species richness are highly uncertain, and the importance of stochastic vs. deterministic forces in the assembly of fungal communities is unknown. Molecular studies have so far failed to reach saturated, comprehensive estimates of fungal diversity. To obtain a more...

  8. Chromosome Segregation in Vibrio cholerae

    OpenAIRE

    Ramachandran, R.; Jha, J.; Chattoraj, DK

    2014-01-01

    The study of chromosome segregation is currently one of the most exciting research frontiers in cell biology. In this review, we discuss our current knowledge of the chromosome segregation process in Vibrio cholerae, based primarily on findings from fluorescence microscopy experiments. This bacterium is of special interest because of its eukaryotic feature of having a divided genome, a feature shared with 10% of known bacteria. We also discuss how the segregation mechanisms of V. cholerae com...

  9. Chromosome segregation in Vibrio cholerae.

    Science.gov (United States)

    Ramachandran, Revathy; Jha, Jyoti; Chattoraj, Dhruba K

    2014-01-01

    The study of chromosome segregation is currently one of the most exciting research frontiers in cell biology. In this review, we discuss our current knowledge of the chromosome segregation process in Vibrio cholerae, based primarily on findings from fluorescence microscopy experiments. This bacterium is of special interest because of its eukaryotic feature of having a divided genome, a feature shared with 10% of known bacteria. We also discuss how the segregation mechanisms of V. cholerae compare with those in other bacteria, and highlight some of the remaining questions regarding the process of bacterial chromosome segregation.

  10. "Fine-scale climatic variation drives altitudinal niche partitioning of tabanid flies in a tropical montane cloud forest, Ecuadorian Choco"

    OpenAIRE

    Cárdenas Muñoz, Rafael Enrique

    2015-01-01

    In montane systems, global warming may lead communities to disassemble by forcing organisms to shift their distributions to higher elevations or by causing the extinction of those that are unable to adapt. To predict which species are most at risk from environmental change, physiological responses to multiple factors must be measured in natural conditions at fine spatial and temporal scales. To examine the potential drivers of elevational distributions in tabanid flies, specimens were exha...

  11. Influence of habitat discontinuity, geographical distance, and oceanography on fine-scale population genetic structure of copper rockfish (Sebastes caurinus).

    Science.gov (United States)

    Johansson, M L; Banks, M A; Glunt, K D; Hassel-Finnegan, H M; Buonaccorsi, V P

    2008-07-01

    The copper rockfish is a benthic, nonmigratory, temperate rocky reef marine species with pelagic larvae and juveniles. A previous range-wide study of the population-genetic structure of copper rockfish revealed a pattern consistent with isolation-by-distance. This could arise from an intrinsically limited dispersal capability in the species or from regularly-spaced extrinsic barriers that restrict gene flow (offshore jets that advect larvae offshore and/or habitat patchiness). Tissue samples were collected along the West Coast of the contiguous USA between Neah Bay, WA and San Diego, CA, with dense sampling along Oregon. At the whole-coast scale (approximately 2200 km), significant population subdivision (F(ST) = 0.0042), and a significant correlation between genetic and geographical distance were observed based on 11 microsatellite DNA loci. Population divergence was also significant among Oregon collections (approximately 450 km, F(ST) = 0.001). Hierarchical amova identified a weak but significant 130-km habitat break as a possible barrier to gene flow within Oregon, across which we estimated that dispersal (N(e)m) is half that of the coast-wide average. However, individual-based Bayesian analyses failed to identify more than a single population along the Oregon coast. In addition, no correlation between pairwise population genetic and geographical distances was detected at this scale. The offshore jet at Cape Blanco was not a significant barrier to gene flow in this species. These findings are consistent with low larval dispersal distances calculated in previous studies on this species, support a mesoscale dispersal model, and highlight the importance of continuity of habitat and adult population size in maintaining gene flow.

  12. Recent demographic history and present fine-scale structure in the Northwest Atlantic leatherback (Dermochelys coriacea turtle population.

    Directory of Open Access Journals (Sweden)

    Erica Molfetti

    Full Text Available The leatherback turtle Dermochelys coriacea is the most widely distributed sea turtle species in the world. It exhibits complex life traits: female homing and migration, migrations of juveniles and males that remain poorly known, and a strong climatic influence on resources, breeding success and sex-ratio. It is consequently challenging to understand population dynamics. Leatherbacks are critically endangered, yet the group from the Northwest Atlantic is currently considered to be under lower risk than other populations while hosting some of the largest rookeries. Here, we investigated the genetic diversity and the demographic history of contrasted rookeries from this group, namely two large nesting populations in French Guiana, and a smaller one in the French West Indies. We used 10 microsatellite loci, of which four are newly isolated, and mitochondrial DNA sequences of the control region and cytochrome b. Both mitochondrial and nuclear markers revealed that the Northwest Atlantic stock of leatherbacks derives from a single ancestral origin, but show current genetic structuration at the scale of nesting sites, with the maintenance of migrants amongst rookeries. Low nuclear genetic diversities are related to founder effects that followed consequent bottlenecks during the late Pleistocene/Holocene. Most probably in response to climatic oscillations, with a possible influence of early human hunting, female effective population sizes collapsed from 2 million to 200. Evidence of founder effects and high numbers of migrants make it possible to reconsider the population dynamics of the species, formerly considered as a metapopulation model: we propose a more relaxed island model, which we expect to be a key element in the currently observed recovering of populations. Although these Northwest Atlantic rookeries should be considered as a single evolutionary unit, we stress that local conservation efforts remain necessary since each nesting site hosts

  13. The Importance of Fine-Scale Flow Processes and Food Availability in the Maintenance of Soft-Sediment Communities

    Science.gov (United States)

    1993-02-01

    variability on a transect in the Gulf of Mexico . Estuarine and Coastal Marine Science, 10, 1-14. Folk, R.L. (1966) A review of grain-size parameters... Gulf of Mexico . Limnologv and -159- Oceanoarajhy. Jumars, P. A., L. M. Mayer, J.W. Deming, J.A. Baross & R.A. Wheatcroft (1990). Deep-sea deposit...carcasses (e.g., Dayton and Hessler, 1972). Some species of benthic foraminifera also occur in high -399- densities in the presence of phytodetritus

  14. Patterns of residential segregation

    CERN Document Server

    Louf, Rémi

    2015-01-01

    The spatial distribution of income shapes the structure and organisation of cities and its understanding has broad societal implications. Despite an abundant literature, many issues remain however unclear: there is no clear definition of what segregation is, no unambiguous definition of income classes, no clear way to identify neighborhoods, and no method to deal with the polycentric organization of large cities. In this paper, we address all these questions within a unique theoretical framework. We assume that households belonging to the same class tend to live close to each other, and households from different classes tend to avoid one another. Applied to the US 2000 Census Income data, 3 distinct classes emerge from the clustering of the original 16 income classes. Using these unambiguously defined classes, we cluster together contiguous similar areas and find that the number of clusters for each category scales with the city population, an effect that is more pronounced for rich households. Finally, using...

  15. Fine-Scale Movements and Behaviors of Whale Sharks, Rhincodon typus, in a Seasonal Aggregation near Al Lith, Saudi Arabia

    KAUST Repository

    Sun, Lu

    2016-12-01

    Movement and behavior studies are traditional yet effective ways to understand the biology and ecology of a species. For an endangered species like the whale shark (Rhincodon typus), a comprehensive knowledge of its movement and behavior is particularly critical for successful management and conservation. For this dissertation, acoustic telemetry and biologging tagging studies were carried out at a seasonal whale shark aggregation site near Al Lith in the Saudi Arabian Red Sea. Acoustic telemetry data revealed consistent path usage in a narrow longshore area with patterns in seasonality and diel horizontal movements within a smaller scale. Some individuals specifically concentrated on this path and made non-stop back and forth movements along it. In another dimension, depth use of whale sharks derived from biologgers showed distinct diel patterns. The sharks heavily utilized shallow waters with mixed depth usage consisting of surface swimming and varied types of dives, which explained the data of previous visual surveys. Vertical velocities indicated potential energy expenditure strategies that were further investigated based on acceleration data. Energy expenditure data suggested strategies that fine-tuned foraging efforts to optimize the balance between feeding and foraging. However, while these strategies fit well in the natural habitat, local human impacts could be of great disturbance if not well managed.

  16. Fine-scale mapping of a locus for severe bipolar mood disorder on chromosome 18p11.3 in the Costa Rican population

    Science.gov (United States)

    McInnes, L. Alison; Service, Susan K.; Reus, Victor I.; Barnes, Glenn; Charlat, Olga; Jawahar, Satya; Lewitzky, Steve; Yang, Qing; Duong, Quyen; Spesny, Mitzi; Araya, Carmen; Araya, Xinia; Gallegos, Alvaro; Meza, Luis; Molina, Julio; Ramirez, Rolando; Mendez, Roxana; Silva, Sandra; Fournier, Eduardo; Batki, Steven L.; Mathews, Carol A.; Neylan, Thomas; Glatt, Charles E.; Escamilla, Michael A.; Luo, David; Gajiwala, Paresh; Song, Terry; Crook, Stephen; Nguyen, Jasmine B.; Roche, Erin; Meyer, Joanne M.; Leon, Pedro; Sandkuijl, Lodewijk A.; Freimer, Nelson B.; Chen, Hong

    2001-01-01

    We have searched for genes predisposing to bipolar disorder (BP) by studying individuals with the most extreme form of the affected phenotype, BP-I, ascertained from the genetically isolated population of the Central Valley of Costa Rica (CVCR). The results of a previous linkage analysis on two extended CVCR BP-I pedigrees, CR001 and CR004, and of linkage disequilibrium (LD) analyses of a CVCR population sample of BP-I patients implicated a candidate region on 18p11.3. We further investigated this region by creating a physical map and developing 4 new microsatellite and 26 single-nucleotide polymorphism markers for typing in the pedigree and population samples. We report the results of fine-scale association analyses in the population sample, as well as evaluation of haplotypes in pedigree CR001. Our results suggest a candidate region containing six genes but also highlight the complexities of LD mapping of common disorders. PMID:11572994

  17. Shaping Segregation: Convexity vs. concavity

    NARCIS (Netherlands)

    Gonzalez, S.; Windows-Yule, C.R.; Luding, S.; Parker, D.J.; Thornton, A.R.

    2014-01-01

    Controlling segregation is both a practical and a theoretical challenge. In this Letter we demonstrate a manner in which rotation-induced segregation may be controlled by altering the geometry of the rotating containers in which granular systems are housed. Using a novel drum design comprising conca

  18. Fine-scale population structure of two anemones (Stichodactyla gigantea and Heteractis magnifica) in Kimbe Bay, Papua New Guinea

    KAUST Repository

    Gatins, Remy

    2014-12-01

    Anemonefish are one of the main groups that have been used over the last decade to empirically measure larval dispersal and connectivity in coral reef populations. A few species of anemones are integral to the life history of these fish, as well as other obligate symbionts, yet the biology and population structure of these anemones remains poorly understood. The aim of this study was to measure the genetic structure of these anemones within and between two reefs in order to assess their reproductive mode and dispersal potential. To do this, we sampled almost exhaustively two anemones species (Stichodactyla gigantea and Heteractis magnifica) at two small islands in Kimbe Bay (Papua New Guinea) separated by approximately 25 km. Both the host anemones and the anemonefish are heavily targeted for the aquarium trade, in addition to the populations being affected by bleaching pressures (Hill and Scott 2012; Hobbs et al. 2013; Saenz- Agudelo et al. 2011; Thomas et al. 2014), therefore understanding their biology is crucial for better management strategies. Panels of microsatellite markers were developed for each species using next generation sequencing tools. Clonality analyses confirm six pairs of identical genotypes for S. gigantea (n=350) and zero for H. magnifica (n=128), indicating presence/absence of asexual reproduction in this region. S. gigantea showed low structure between islands (FST= 0.003, p-value= 0.000), however, even if the majority of the individuals were unrelated (r~0), 81 families that shared 50% of their genetic material formed from two to four members were found. Out of these families, 45% were found with individuals only within Tuare Island, 11% only in Kimbe Island, and 44% were sharing individuals among islands. In comparison, H. magnifica showed no structure (FST= 0.002, p-value= 0.278), mean relatedness indicated the majority of individuals were unrelated, and 31 families were identified. Families again consisted from two to four members and

  19. Predators determine how weather affects the spatial niche of lizard prey: exploring niche dynamics at a fine scale.

    Science.gov (United States)

    Lopez-Darias, Marta; Schoener, Thomas W; Spiller, David A; Losos, Jonathan B

    2012-12-01

    Although abiotic and biotic factors can interact to shape the spatial niche of a species, studies that explore the interactive effects of both at a local scale are rare. We demonstrate that one of the main axes (perch height) characterizing the spatial niche of a common lizard, Anolis sagrei, varies according to the interactive effects of weather and the activity of a larger predatory lizard, Leiocephalus carinatus. Results were completely consistent: no matter how favorable the weather conditions for using the ground (mainly characterized by temperature, humidity, wind speed, rain), A. sagrei did not do so if the predator was present. Hence, great behavioral plasticity enabled A. sagrei to adjust its use of space very quickly. To the best of our knowledge, these results constitute the first field demonstration for anoles (and possibly for other animals as well) of how time-varying environmental conditions and predator presence interact to produce short-term changes in utilization along a major niche axis.

  20. Influenza-A viruses in ducks in northwestern Minnesota: fine scale spatial and temporal variation in prevalence and subtype diversity.

    Directory of Open Access Journals (Sweden)

    Benjamin R Wilcox

    Full Text Available Waterfowl from northwestern Minnesota were sampled by cloacal swabbing for Avian Influenza Virus (AIV from July-October in 2007 and 2008. AIV was detected in 222 (9.1% of 2,441 ducks in 2007 and in 438 (17.9% of 2,452 ducks in 2008. Prevalence of AIV peaked in late summer. We detected 27 AIV subtypes during 2007 and 31 during 2008. Ten hemagglutinin (HA subtypes were detected each year (i.e., H1, 3-8, and 10-12 during 2007; H1-8, 10 and 11 during 2008. All neuraminidase (NA subtypes were detected during each year of the study. Subtype diversity varied between years and increased with prevalence into September. Predominant subtypes during 2007 (comprising ≥5% of subtype diversity included H1N1, H3N6, H3N8, H4N6, H7N3, H10N7, and H11N9. Predominant subtypes during 2008 included H3N6, H3N8, H4N6, H4N8, H6N1, and H10N7. Additionally, within each HA subtype, the same predominant HA/NA subtype combinations were detected each year and included H1N1, H3N8, H4N6, H5N2, H6N1, H7N3, H8N4, H10N7, and H11N9. The H2N3 and H12N5 viruses also predominated within the H2 and H12 subtypes, respectively, but only were detected during a single year (H2 and H12 viruses were not detected during 2007 and 2008, respectively. Mallards were the predominant species sampled (63.7% of the total, and 531 AIV were isolated from this species (80.5% of the total isolates. Mallard data collected during both years adequately described the observed temporal and spatial prevalence from the total sample and also adequately represented subtype diversity. Juvenile mallards also were adequate in describing the temporal and spatial prevalence of AIV as well as subtype diversity.

  1. Fine-scale responses of phytoplankton to freshwater influx in a tropical monsoonal estuary following the onset of southwest monsoon

    Indian Academy of Sciences (India)

    Suraksha M Pednekar; S G Prabhu Matondkar; Helga Do R Gomes; Joaquim I Goes; Sushma Parab; Vijaya Kerkar

    2011-06-01

    In May of 2007, a study was initiated by the National Institute of Oceanography (NIO), Goa, India, to investigate the influence of monsoonal rainfall on hydrographic conditions in the Mandovi River of India. The study was undertaken at a location ∼2 km upstream of the mouth of this estuary. During the premonsoon (PreM) in May, when circulation in the estuary was dominated by tidal activity, phytoplankton communities in the high saline (35–37 psu) waters at the study site were largely made up of the coastal neritic species Fragilaria oceanica, Ditylum brightwellii and Trichodesmium erythraeum. During the later part of the intermonsoon (InterM) phase, an abrupt decline in salinity led to a surge in phytoplankton biomass (Chlorophyll ∼14 mg m−3), of a population that was dominated by Thalassiosira eccentricus. As the southwest monsoon (SWM) progressed and the estuary freshened salinity and Chlorophyll (Chl ) concentrations decreased during the MoN, Skeletonema costatum established itself as the dominant form. Despite the low biomass (Chl > 2 mg m−3), the phytoplankton community of the MoN was the most diverse of the entire study. During the postmonsoon (PostM), the increase in salinity was marked by a surge in dinoflagellate populations comprising of Ceratium furca, Akashiwo sanguinea, and Pyrophacus horologium.

  2. Fine-scale local adaptation of weevil mouthpart length and camellia pericarp thickness: altitudinal gradient of a putative arms race.

    Science.gov (United States)

    Toju, Hirokazu

    2008-05-01

    Although coevolutionary theory predicts that evolutionary interactions between species are spatially hierarchical, few studies have examined coevolutionary processes at multiple spatial scales. In an antagonistic system involving a plant, the Japanese camellia (Camellia japonica), and its obligate seed predator, the camellia weevil (Curculio camelliae), I elucidated the local adaptation of a camellia defensive armament (pericarp thickness) and a weevil offensive armament (rostrum length) within Yakushima Island (ca. 30 km in diameter), compared to a larger-scale variation in those traits throughout Japan reported in previous studies. Results showed that camellia pericarp thickness and weevil rostrum length vary remarkably within several kilometers on this island. In addition, geographic variation in each camellia and weevil armament was best explained by the armament size of the sympatric participant than by abiotic environmental heterogeneity. However, I also found that camellia pericarp thickness significantly decreased in cool-temperate (i.e., highland) areas, suggesting the contributions of climate on the spatial structuring of the weevil-camellia interaction. Interestingly, relatively thin pericarps occurred not only in the highlands but also in some low-altitude areas, indicating that other factors such as nonrandom or asymmetric gene flow play important roles in the metapopulation processes of interspecific interactions at small spatial scales.

  3. Fine-scale population differentiation and gene flow in a terrestrial salamander (Plethodon cinereus) living in continuous habitat.

    Science.gov (United States)

    Cabe, P R; Page, R B; Hanlon, T J; Aldrich, M E; Connors, L; Marsh, D M

    2007-01-01

    Several recent studies have shown that amphibian populations may exhibit high genetic subdivision in areas with recent fragmentation and urban development. Less is known about the potential for genetic differentiation in continuous habitats. We studied genetic differentiation of red-backed salamanders (Plethodon cinereus) across a 2-km transect through continuous forest in Virginia, USA. Mark-recapture studies suggest very little dispersal for this species, whereas homing experiments and post-Pleistocene range expansion both suggest greater dispersal abilities. We used six microsatellite loci to examine genetic population structure and differentiation between eight subpopulations of red-backed salamanders at distances from 200 m to 2 km. We also used several methods to extrapolate dispersal frequencies and test for sex-biased dispersal. We found small, but detectable differentiation among populations, even at distances as small as 200 m. Differentiation was closely correlated with distance and both Mantel tests and assignment tests were consistent with an isolation-by-distance model for the population. Extrapolations of intergenerational variance in spatial position (sigma(2)<15 m(2)) and pair-wise dispersal frequencies (4 Nm < 25 for plots separated by 300 m) both suggest limited gene flow. Additionally, tests for sex-biased dispersal imply that dispersal frequency is similarly low for both sexes. We suggest that these low levels of gene flow and the infrequent dispersal observed in mark-recapture studies may be reconciled with homing ability and range expansion if dispersing animals rarely succeed in breeding in saturated habitats, if dispersal is flexible depending on the availability of habitat, or if dispersal frequency varies across the geographic range of red-backed salamanders.

  4. Multiple SNP markers reveal fine-scale population and deep phylogeographic structure in European anchovy (Engraulis encrasicolus L.).

    KAUST Repository

    Zarraonaindia, Iratxe

    2012-07-30

    Geographic surveys of allozymes, microsatellites, nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) have detected several genetic subdivisions among European anchovy populations. However, these studies have been limited in their power to detect some aspects of population structure by the use of a single or a few molecular markers, or by limited geographic sampling. We use a multi-marker approach, 47 nDNA and 15 mtDNA single nucleotide polymorphisms (SNPs), to analyze 626 European anchovies from the whole range of the species to resolve shallow and deep levels of population structure. Nuclear SNPs define 10 genetic entities within two larger genetically distinctive groups associated with oceanic variables and different life-history traits. MtDNA SNPs define two deep phylogroups that reflect ancient dispersals and colonizations. These markers define two ecological groups. One major group of Iberian-Atlantic populations is associated with upwelling areas on narrow continental shelves and includes populations spawning and overwintering in coastal areas. A second major group includes northern populations in the North East (NE) Atlantic (including the Bay of Biscay) and the Mediterranean and is associated with wide continental shelves with local larval retention currents. This group tends to spawn and overwinter in oceanic areas. These two groups encompass ten populations that differ from previously defined management stocks in the Alboran Sea, Iberian-Atlantic and Bay of Biscay regions. In addition, a new North Sea-English Channel stock is defined. SNPs indicate that some populations in the Bay of Biscay are genetically closer to North Western (NW) Mediterranean populations than to other populations in the NE Atlantic, likely due to colonizations of the Bay of Biscay and NW Mediterranean by migrants from a common ancestral population. Northern NE Atlantic populations were subsequently established by migrants from the Bay of Biscay. Populations along the Iberian

  5. Chromosome segregation in plant meiosis

    Science.gov (United States)

    Zamariola, Linda; Tiang, Choon Lin; De Storme, Nico; Pawlowski, Wojtek; Geelen, Danny

    2014-01-01

    Faithful chromosome segregation in meiosis is essential for ploidy stability over sexual life cycles. In plants, defective chromosome segregation caused by gene mutations or other factors leads to the formation of unbalanced or unreduced gametes creating aneuploid or polyploid progeny, respectively. Accurate segregation requires the coordinated execution of conserved processes occurring throughout the two meiotic cell divisions. Synapsis and recombination ensure the establishment of chiasmata that hold homologous chromosomes together allowing their correct segregation in the first meiotic division, which is also tightly regulated by cell-cycle dependent release of cohesin and monopolar attachment of sister kinetochores to microtubules. In meiosis II, bi-orientation of sister kinetochores and proper spindle orientation correctly segregate chromosomes in four haploid cells. Checkpoint mechanisms acting at kinetochores control the accuracy of kinetochore-microtubule attachment, thus ensuring the completion of segregation. Here we review the current knowledge on the processes taking place during chromosome segregation in plant meiosis, focusing on the characterization of the molecular factors involved. PMID:24987397

  6. Chromosome segregation in plant meiosis

    Directory of Open Access Journals (Sweden)

    Linda eZamariola

    2014-06-01

    Full Text Available Faithful chromosome segregation in meiosis is essential for ploidy stability over sexual life cycles. In plants, defective chromosome segregation caused by gene mutations or other factors leads to the formation of unbalanced or unreduced gametes creating aneuploid or polyploid progeny, respectively. Accurate segregation requires the coordinated execution of conserved processes occurring throughout the two meiotic cell divisions. Synapsis and recombination ensure the establishment of chiasmata that hold homologous chromosomes together allowing their correct segregation in the first meiotic division, which is also tightly regulated by cell-cycle dependent release of cohesin and monopolar attachment of sister kinetochores to microtubules. In meiosis II, bi-orientation of sister kinetochores and proper spindle orientation correctly segregate chromosomes in four haploid cells. Checkpoint mechanisms acting at kinetochores control the accuracy of kinetochore-microtubule attachment, thus ensuring the completion of segregation. Here we review the current knowledge on the processes taking place during chromosome segregation in plant meiosis, focusing on the characterization of the molecular factors involved.

  7. Source Segregation and Collection of Source-Segregated Waste

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Matsufuji, Y.

    2011-01-01

    of optimal handling of the waste. But in a few cases, the waste must also be separated at source, for example removing the protective plastic cover from a commercial advertisement received by mail, prior to putting the advertisement into the waste collection bin for recyclable paper. These issues are often......The Segregation of individual material fractions at the waste source and keeping the fractions separate for collection is one of the key issues in modern waste management. In most cases the waste is just kept segregated from other waste according to certain criteria that improve the possibility...... termed source separation or sorting at source. Here the word segregation has been chosen to indicate the importance of keeping the waste fractions apart by sorting waste and by separating waste into segregated materials as it is generated. The more waste that a physically defined source generates...

  8. Inherent Segregation in Granular Media

    Directory of Open Access Journals (Sweden)

    Sánchez-Guzmán J.

    2011-10-01

    Full Text Available A study of the inherent segregation within granular media due to the relative size of the different particles is presented. A numerical model is used to simulate granular structures. For both simulation and granular structures evaluations, probability theory is widely used. Particles are idealized by disks (2D model and spheres (3D model. Strictly uniform grain size materials, bimodal (two particle sizes and continuous are simulated. Two variables representing segregation and allowing appreciating the grain-size parameters effects are considered. In uniform materials, the presence of spontaneous structuring is observed. In bimodal and continuous materials, inherent segregation mainly depends on the ratio between maximum and minimum diameters of particle. Some practical implications of inherent segregation in geotechnical problems and other disciplines are remarked.

  9. Can topology reshape segregation patterns?

    CERN Document Server

    Gandica, Yerali; Carletti, Timoteo

    2015-01-01

    We consider a metapopulation version of the Schelling model of segregation over several complex networks and lattice. We show that the segregation process is topology independent and hence it is intrinsic to the individual tolerance. The role of the topology is to fix the places where the segregation patterns emerge. In addition we address the question of the time evolution of the segregation clusters, resulting from different dynamical regimes of a coarsening process, as a function of the tolerance parameter. We show that the underlying topology may alter the early stage of the coarsening process, once large values of the tolerance are used, while for lower ones a different mechanism is at work and it results to be topology independent.

  10. Direct genetic evidence for reproductive philopatry and associated fine-scale migrations in female blacktip reef sharks (Carcharhinus melanopterus) in French Polynesia.

    Science.gov (United States)

    Mourier, Johann; Planes, Serge

    2013-01-01

    Conservation of top predators has been emphasized as essential in an ecosystem due to their role in trophic chain regulation. Optimizing conservation strategies for these endangered marine top predators requires direct estimates of breeding patterns and connectivity as these are essential to understanding the population dynamics. There have been some attempts to investigate breeding patterns of reef sharks from litter reconstruction using molecular analyses. However, direct fine-scale migrations of female sharks for parturition as well as connectivity at a medium scale like between islands remain mostly unknown. We used microsatellite DNA markers and a likelihood-based parentage analysis to determine breeding patterns of female blacktip reef sharks in Moorea (Society Islands, French Polynesia). Most females gave birth at their home island but some migrated to specific nursery areas outside the area they are attached to, sometimes going to another island 50 km away across deep ocean. Our analysis also revealed that females migrated to the same nursery for every birthing event. Many offspring showed a high level of inbreeding indicating an overall reduced population size, restricted movements and dispersal, or specific mating behaviour. Females represent the vectors that transport the genes at nursery grounds, and their fidelity should thus define reproductive units. As females seem to be philopatric, males could be the ones dispersing genes between populations. These results highlight the need to conserve coastal zones where female reef sharks seem to exhibit philopatry during the breeding season.

  11. Modulation of habitat-based conservation plans by fishery opportunity costs: a New Caledonia case study using fine-scale catch data.

    Directory of Open Access Journals (Sweden)

    Marilyn Deas

    Full Text Available Numerous threats impact coral reefs and conservation actions are urgently needed. Fast production of marine habitat maps promotes the use of habitat-only conservation plans, where a given percentage of the area of each habitat is set as conservation objectives. However, marine reserves can impact access to fishing grounds and generate opportunity costs for fishers that need to be minimized. In New Caledonia (Southwest Pacific, we used fine-scale fishery catch maps to define nineteen opportunity costs layers (expressed as biomass catch loss considering i total catches, ii target fish families, iii local marine tenure, and iv gear type. The expected lower impacts on fishery catch when using the different cost constraints were ranked according to effectiveness in decreasing the costs generated by the habitat-only scenarios. The exercise was done for two habitat maps with different thematic richness. In most cases, habitat conservation objectives remained achievable, but effectiveness varied widely between scenarios and between habitat maps. The results provide practical guidelines for coral reef conservation and management. Habitat-only scenarios can be used to initiate conservation projects with stakeholders but the costs induced by such scenarios can be lowered by up to 50-60% when detailed exhaustive fishery data are used. When using partial data, the gain would be only in the 15-25% range. The best compromises are achieved when using local data.

  12. Fine scale daily movements and habitat use of East Pacific green turtles at a shallow coastal lagoon in Baja California Sur, Mexico

    Science.gov (United States)

    Senko, Jesse; Koch, Volker; Megill, William M.; Carthy, Raymond R.; Templeton, R.obert P.; Nichols, Wallace J.

    2010-01-01

    Green turtles spend most of their lives in coastal foraging areas where they face multiple anthropogenic impacts. Therefore, understanding their spatial use in this environment is a priority for conservation efforts. We studied the fine scale daily movements and habitat use of East Pacific green turtles (Chelonia mydas) at Laguna San Ignacio, a shallow coastal lagoon in Baja California Sur, Mexico where sea turtles are subject to high levels of gillnet bycatch and directed hunting. Six turtles ranging from 44.6 to 83.5 cm in straight carapace length were tracked for short deployments (1 to 6 d) with GPS-VHF telemetry. Turtles were active throughout diurnal, nocturnal, and crepuscular periods. Although they moved greater total distances during daytime, their speed of travel and net displacement remained consistent throughout 24-h periods. A positive selection for areas of seagrass and moderate water depth (5 to 10 m) was determined using Ivlev's electivity index, with neutral selection for shallow water ( 10 m). Turtles exhibited two distinct behavioral movement patterns: circular movements with high fidelity to the capture–release location and meandering movements with low fidelity to the capture–release location. Our results indicate that green turtles were active throughout the diel cycle while traveling large distances and traversing multiple habitats over short temporal scales.

  13. Research on the Fine-Scale Spatial Uniformity of Natural Rainfall and Rainfall from a Rainfall Simulator with a Rotary Platform (RSRP

    Directory of Open Access Journals (Sweden)

    Bo Liu

    2017-06-01

    Full Text Available Abstract: The accurate production of a rainfall environment similar to natural rainfall by a rainfall simulator (RS is a crucial and challenging task in rainfall instrument testing or calibration. Although the spatial uniformity of rainfall accumulation is a key parameter of an RS, the spatial uniformity comparison between simulated rainfall and natural rainfall, and the spatial uniformity improvements for an RS are scant in the literature. In this study, a fine-scale natural rainfall experiment was studied using the same testing methods of an RS and the rainfall uniformity was evaluated using the Christiansen Uniformity Coefficient (CU. Simultaneously, factors influencing the spatial uniformity of natural rainfall, including the average rainfall accumulation (RA, the deviation of RA, and the area of the test zone, were analyzed. The results successfully reproduced some of the behaviors observed in natural rainfall experiments, showing that CU is dependent on these parameters. Based on these studies, we developed a rainfall simulator with a rotary platform (RSRP and found that although spatial uniformity of the RSRP was greatly improved using an appropriate rotary speed, it was not consistent with the spatial uniformity of natural rainfall. Furthermore, we tested four tipping-bucket rain gauges using this imperfect RSRP, and found that the RSRP might acquire the instrumental errors associated with RA for a tested rainfall instrument.

  14. Fine-scale movements of rural free-ranging dogs in conservation areas in the temperate rainforest of the coastal range of southern Chile

    Science.gov (United States)

    Sepulveda, Maximiliano; Pelican, Katherine; Cross, Paul C.; Eguren, Antonieta; Singer, Randall S.

    2015-01-01

    Domestic dogs can play a variety of important roles for farmers. However, when in proximity to conservation areas, the presence of rural free-ranging dogs can be problematic due to the potential for predation of, competition with, or transmission of infectious disease to local threatened fauna. We used a frequent location radio tracking technology to study rural free-ranging dog movements and habitat use into sensitive conservation habitats. To achieve a better understanding of foray behaviors in dogs we monitored dogs (n = 14) in rural households located in an isolated area between the Valdivian Coastal Reserve and the Alerce Costero National Park in southern Chile. Dogs were mostly located near households (Dogs spent, on average, 5.3% of their time in forays with average per dog foray distances from the house ranging 0.5–1.9 km (maximum distance detected 4.3 km). Foraying behavior was positively associated with pasture habitat compared to forest habitat including protected lands. Foraying dogs rarely used forest habitat and, when entered, trails and/or roads were selected for movement. Our study provides important information about how dogs interact in a fine-scale with wildlife habitat, and, in particular, protected lands, providing insight into how dog behavior might drive wildlife interactions, and, in turn, how an understanding of dog behavior can be used to manage these interactions.

  15. Fine-Scale Mapping at 9p22.2 Identifies Candidate Causal Variants That Modify Ovarian Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

    DEFF Research Database (Denmark)

    Vigorito, Elena; Kuchenbaecker, Karoline B; Beesley, Jonathan;

    2016-01-01

    Population-based genome wide association studies have identified a locus at 9p22.2 associated with ovarian cancer risk, which also modifies ovarian cancer risk in BRCA1 and BRCA2 mutation carriers. We conducted fine-scale mapping at 9p22.2 to identify potential causal variants in BRCA1 and BRCA2...... mutation carriers. Genotype data were available for 15,252 (2,462 ovarian cancer cases) BRCA1 and 8,211 (631 ovarian cancer cases) BRCA2 mutation carriers. Following genotype imputation, ovarian cancer associations were assessed for 4,873 and 5,020 SNPs in BRCA1 and BRCA 2 mutation carriers respectively......, within a retrospective cohort analytical framework. In BRCA1 mutation carriers one set of eight correlated candidate causal variants for ovarian cancer risk modification was identified (top SNP rs10124837, HR: 0.73, 95%CI: 0.68 to 0.79, p-value 2× 10-16). These variants were located up to 20 kb upstream...

  16. Controlling segregation speed of entangled polymers by the shapes: A simple model for eukaryotic chromosome segregation

    Science.gov (United States)

    Sakai, Yuji; Tachikawa, Masashi; Mochizuki, Atsushi

    2016-10-01

    We report molecular dynamics simulations of the segregation of two overlapping polymers motivated by chromosome segregation in biological cells. We investigate the relationship between polymer shapes and segregation dynamics and show that elongation and compaction make entangled polymers segregate rapidly. This result suggests that eukaryotic chromosomes take such a characteristic rod-shaped structure, which is induced by condensins, to achieve rapid segregation.

  17. Statistical analysis of atom probe data: detecting the early stages of solute clustering and/or co-segregation.

    Science.gov (United States)

    Hyde, J M; Cerezo, A; Williams, T J

    2009-04-01

    Statistical analysis of atom probe data has improved dramatically in the last decade and it is now possible to determine the size, the number density and the composition of individual clusters or precipitates such as those formed in reactor pressure vessel (RPV) steels during irradiation. However, the characterisation of the onset of clustering or co-segregation is more difficult and has traditionally focused on the use of composition frequency distributions (for detecting clustering) and contingency tables (for detecting co-segregation). In this work, the authors investigate the possibility of directly examining the neighbourhood of each individual solute atom as a means of identifying the onset of solute clustering and/or co-segregation. The methodology involves comparing the mean observed composition around a particular type of solute with that expected from the overall composition of the material. The methodology has been applied to atom probe data obtained from several irradiated RPV steels. The results show that the new approach is more sensitive to fine scale clustering and co-segregation than that achievable using composition frequency distribution and contingency table analyses.

  18. Modeling of particle size segregation: calibration using the discrete particle method

    NARCIS (Netherlands)

    Thornton, Anthony; Weinhart, Thomas; Luding, Stefan; Bokhove, Onno

    2012-01-01

    Over the last 25 years a lot of work has been undertaken on constructing continuum models for segregation of particles of different sizes. We focus on one model that is designed to predict segregation and remixing of two differently sized particle species. This model contains two dimensionless param

  19. Continuum modeling of segregation for tridisperse granular materials in developing chute flow

    Science.gov (United States)

    Deng, Zhekai; Umbanhowar, Paul; Lueptow, Richard

    2015-11-01

    Predicting segregation and mixing of size polydisperse granular material is a challenging problem and is relevant to many industrial applications. We develop and implement a continuum-based theoretical model that captures the effects of segregation, diffusion and advection on size tridisperse granular flow in developing quasi-two-dimensional chute flow. Unlike segregation models that rely on arbitrary fitting parameters, our model uses parameters based on kinematics measured using discrete element method (DEM) simulations. The model depends on both the Péclet number, Pe, which we defined as the ratio of the segregation rate to the diffusion rate, and the relative segregation strength between particle species. At large Pe, segregation dominates and chute flow consists of distinct stratified regions of small(bottom), medium(center) and large (top) particles, whereas at small Pe, diffusion dominates, which results in a well mixed flow. As relative segregation strength between any two particle species is increased, the segregation between them becomes quicker. However, as relative segregation strength between them is decreased, they remain mixed with each other. Preliminary results from DEM simulations support our theoretical model.

  20. Grain Boundary Segregation in Metals

    CERN Document Server

    Lejcek, Pavel

    2010-01-01

    Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.

  1. Fine-Scale Mapping at 9p22.2 Identifies Candidate Causal Variants That Modify Ovarian Cancer Risk in BRCA1 and BRCA2 Mutation Carriers.

    Science.gov (United States)

    Vigorito, Elena; Kuchenbaecker, Karoline B; Beesley, Jonathan; Adlard, Julian; Agnarsson, Bjarni A; Andrulis, Irene L; Arun, Banu K; Barjhoux, Laure; Belotti, Muriel; Benitez, Javier; Berger, Andreas; Bojesen, Anders; Bonanni, Bernardo; Brewer, Carole; Caldes, Trinidad; Caligo, Maria A; Campbell, Ian; Chan, Salina B; Claes, Kathleen B M; Cohn, David E; Cook, Jackie; Daly, Mary B; Damiola, Francesca; Davidson, Rosemarie; Pauw, Antoine de; Delnatte, Capucine; Diez, Orland; Domchek, Susan M; Dumont, Martine; Durda, Katarzyna; Dworniczak, Bernd; Easton, Douglas F; Eccles, Diana; Edwinsdotter Ardnor, Christina; Eeles, Ros; Ejlertsen, Bent; Ellis, Steve; Evans, D Gareth; Feliubadalo, Lidia; Fostira, Florentia; Foulkes, William D; Friedman, Eitan; Frost, Debra; Gaddam, Pragna; Ganz, Patricia A; Garber, Judy; Garcia-Barberan, Vanesa; Gauthier-Villars, Marion; Gehrig, Andrea; Gerdes, Anne-Marie; Giraud, Sophie; Godwin, Andrew K; Goldgar, David E; Hake, Christopher R; Hansen, Thomas V O; Healey, Sue; Hodgson, Shirley; Hogervorst, Frans B L; Houdayer, Claude; Hulick, Peter J; Imyanitov, Evgeny N; Isaacs, Claudine; Izatt, Louise; Izquierdo, Angel; Jacobs, Lauren; Jakubowska, Anna; Janavicius, Ramunas; Jaworska-Bieniek, Katarzyna; Jensen, Uffe Birk; John, Esther M; Vijai, Joseph; Karlan, Beth Y; Kast, Karin; Investigators, KConFab; Khan, Sofia; Kwong, Ava; Laitman, Yael; Lester, Jenny; Lesueur, Fabienne; Liljegren, Annelie; Lubinski, Jan; Mai, Phuong L; Manoukian, Siranoush; Mazoyer, Sylvie; Meindl, Alfons; Mensenkamp, Arjen R; Montagna, Marco; Nathanson, Katherine L; Neuhausen, Susan L; Nevanlinna, Heli; Niederacher, Dieter; Olah, Edith; Olopade, Olufunmilayo I; Ong, Kai-Ren; Osorio, Ana; Park, Sue Kyung; Paulsson-Karlsson, Ylva; Pedersen, Inge Sokilde; Peissel, Bernard; Peterlongo, Paolo; Pfeiler, Georg; Phelan, Catherine M; Piedmonte, Marion; Poppe, Bruce; Pujana, Miquel Angel; Radice, Paolo; Rennert, Gad; Rodriguez, Gustavo C; Rookus, Matti A; Ross, Eric A; Schmutzler, Rita Katharina; Simard, Jacques; Singer, Christian F; Slavin, Thomas P; Soucy, Penny; Southey, Melissa; Steinemann, Doris; Stoppa-Lyonnet, Dominique; Sukiennicki, Grzegorz; Sutter, Christian; Szabo, Csilla I; Tea, Muy-Kheng; Teixeira, Manuel R; Teo, Soo-Hwang; Terry, Mary Beth; Thomassen, Mads; Tibiletti, Maria Grazia; Tihomirova, Laima; Tognazzo, Silvia; van Rensburg, Elizabeth J; Varesco, Liliana; Varon-Mateeva, Raymonda; Vratimos, Athanassios; Weitzel, Jeffrey N; McGuffog, Lesley; Kirk, Judy; Toland, Amanda Ewart; Hamann, Ute; Lindor, Noralane; Ramus, Susan J; Greene, Mark H; Couch, Fergus J; Offit, Kenneth; Pharoah, Paul D P; Chenevix-Trench, Georgia; Antoniou, Antonis C

    2016-01-01

    Population-based genome wide association studies have identified a locus at 9p22.2 associated with ovarian cancer risk, which also modifies ovarian cancer risk in BRCA1 and BRCA2 mutation carriers. We conducted fine-scale mapping at 9p22.2 to identify potential causal variants in BRCA1 and BRCA2 mutation carriers. Genotype data were available for 15,252 (2,462 ovarian cancer cases) BRCA1 and 8,211 (631 ovarian cancer cases) BRCA2 mutation carriers. Following genotype imputation, ovarian cancer associations were assessed for 4,873 and 5,020 SNPs in BRCA1 and BRCA 2 mutation carriers respectively, within a retrospective cohort analytical framework. In BRCA1 mutation carriers one set of eight correlated candidate causal variants for ovarian cancer risk modification was identified (top SNP rs10124837, HR: 0.73, 95%CI: 0.68 to 0.79, p-value 2× 10-16). These variants were located up to 20 kb upstream of BNC2. In BRCA2 mutation carriers one region, up to 45 kb upstream of BNC2, and containing 100 correlated SNPs was identified as candidate causal (top SNP rs62543585, HR: 0.69, 95%CI: 0.59 to 0.80, p-value 1.0 × 10-6). The candidate causal in BRCA1 mutation carriers did not include the strongest associated variant at this locus in the general population. In sum, we identified a set of candidate causal variants in a region that encompasses the BNC2 transcription start site. The ovarian cancer association at 9p22.2 may be mediated by different variants in BRCA1 mutation carriers and in the general population. Thus, potentially different mechanisms may underlie ovarian cancer risk for mutation carriers and the general population.

  2. An Efficient Upscaling Process Based on a Unified Fine-scale Multi-Physics Model for Flow Simulation in Naturally Fracture Carbonate Karst Reservoirs

    KAUST Repository

    Bi, Linfeng

    2009-01-01

    The main challenges in modeling fluid flow through naturally-fractured carbonate karst reservoirs are how to address various flow physics in complex geological architectures due to the presence of vugs and caves which are connected via fracture networks at multiple scales. In this paper, we present a unified multi-physics model that adapts to the complex flow regime through naturally-fractured carbonate karst reservoirs. This approach generalizes Stokes-Brinkman model (Popov et al. 2007). The fracture networks provide the essential connection between the caves in carbonate karst reservoirs. It is thus very important to resolve the flow in fracture network and the interaction between fractures and caves to better understand the complex flow behavior. The idea is to use Stokes-Brinkman model to represent flow through rock matrix, void caves as well as intermediate flows in very high permeability regions and to use an idea similar to discrete fracture network model to represent flow in fracture network. Consequently, various numerical solution strategies can be efficiently applied to greatly improve the computational efficiency in flow simulations. We have applied this unified multi-physics model as a fine-scale flow solver in scale-up computations. Both local and global scale-up are considered. It is found that global scale-up has much more accurate than local scale-up. Global scale-up requires the solution of global flow problems on fine grid, which generally is computationally expensive. The proposed model has the ability to deal with large number of fractures and caves, which facilitate the application of Stokes-Brinkman model in global scale-up computation. The proposed model flexibly adapts to the different flow physics in naturally-fractured carbonate karst reservoirs in a simple and effective way. It certainly extends modeling and predicting capability in efficient development of this important type of reservoir.

  3. Fine-Scale Mapping at 9p22.2 Identifies Candidate Causal Variants That Modify Ovarian Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

    Science.gov (United States)

    Vigorito, Elena; Kuchenbaecker, Karoline B.; Beesley, Jonathan; Adlard, Julian; Agnarsson, Bjarni A.; Andrulis, Irene L.; Arun, Banu K.; Barjhoux, Laure; Belotti, Muriel; Benitez, Javier; Berger, Andreas; Bojesen, Anders; Bonanni, Bernardo; Brewer, Carole; Caldes, Trinidad; Caligo, Maria A.; Campbell, Ian; Chan, Salina B.; Claes, Kathleen B. M.; Cohn, David E.; Cook, Jackie; Daly, Mary B.; Damiola, Francesca; Davidson, Rosemarie; de Pauw, Antoine; Delnatte, Capucine; Diez, Orland; Domchek, Susan M.; Dumont, Martine; Durda, Katarzyna; Dworniczak, Bernd; Easton, Douglas F.; Eccles, Diana; Edwinsdotter Ardnor, Christina; Eeles, Ros; Ejlertsen, Bent; Ellis, Steve; Evans, D. Gareth; Feliubadalo, Lidia; Fostira, Florentia; Foulkes, William D.; Friedman, Eitan; Frost, Debra; Gaddam, Pragna; Ganz, Patricia A.; Garber, Judy; Garcia-Barberan, Vanesa; Gauthier-Villars, Marion; Gehrig, Andrea; Gerdes, Anne-Marie; Giraud, Sophie; Godwin, Andrew K.; Goldgar, David E.; Hake, Christopher R.; Hansen, Thomas V. O.; Healey, Sue; Hodgson, Shirley; Hogervorst, Frans B. L.; Houdayer, Claude; Hulick, Peter J.; Imyanitov, Evgeny N.; Isaacs, Claudine; Izatt, Louise; Izquierdo, Angel; Jacobs, Lauren; Jakubowska, Anna; Janavicius, Ramunas; Jaworska-Bieniek, Katarzyna; Jensen, Uffe Birk; John, Esther M.; Vijai, Joseph; Karlan, Beth Y.; Kast, Karin; Investigators, KConFab; Khan, Sofia; Kwong, Ava; Laitman, Yael; Lester, Jenny; Lesueur, Fabienne; Liljegren, Annelie; Lubinski, Jan; Mai, Phuong L.; Manoukian, Siranoush; Mazoyer, Sylvie; Meindl, Alfons; Mensenkamp, Arjen R.; Montagna, Marco; Nathanson, Katherine L.; Neuhausen, Susan L.; Nevanlinna, Heli; Niederacher, Dieter; Olah, Edith; Olopade, Olufunmilayo I.; Ong, Kai-ren; Osorio, Ana; Park, Sue Kyung; Paulsson-Karlsson, Ylva; Pedersen, Inge Sokilde; Peissel, Bernard; Peterlongo, Paolo; Pfeiler, Georg; Phelan, Catherine M.; Piedmonte, Marion; Poppe, Bruce; Pujana, Miquel Angel; Radice, Paolo; Rennert, Gad; Rodriguez, Gustavo C.; Rookus, Matti A.; Ross, Eric A.; Schmutzler, Rita Katharina; Simard, Jacques; Singer, Christian F.; Slavin, Thomas P.; Soucy, Penny; Southey, Melissa; Steinemann, Doris; Stoppa-Lyonnet, Dominique; Sukiennicki, Grzegorz; Sutter, Christian; Szabo, Csilla I.; Tea, Muy-Kheng; Teixeira, Manuel R.; Teo, Soo-Hwang; Terry, Mary Beth; Thomassen, Mads; Tibiletti, Maria Grazia; Tihomirova, Laima; Tognazzo, Silvia; van Rensburg, Elizabeth J.; Varesco, Liliana; Varon-Mateeva, Raymonda; Vratimos, Athanassios; Weitzel, Jeffrey N.; McGuffog, Lesley; Kirk, Judy; Toland, Amanda Ewart; Hamann, Ute; Lindor, Noralane; Ramus, Susan J.; Greene, Mark H.; Couch, Fergus J.; Offit, Kenneth; Pharoah, Paul D. P.; Chenevix-Trench, Georgia; Antoniou, Antonis C.

    2016-01-01

    Population-based genome wide association studies have identified a locus at 9p22.2 associated with ovarian cancer risk, which also modifies ovarian cancer risk in BRCA1 and BRCA2 mutation carriers. We conducted fine-scale mapping at 9p22.2 to identify potential causal variants in BRCA1 and BRCA2 mutation carriers. Genotype data were available for 15,252 (2,462 ovarian cancer cases) BRCA1 and 8,211 (631 ovarian cancer cases) BRCA2 mutation carriers. Following genotype imputation, ovarian cancer associations were assessed for 4,873 and 5,020 SNPs in BRCA1 and BRCA 2 mutation carriers respectively, within a retrospective cohort analytical framework. In BRCA1 mutation carriers one set of eight correlated candidate causal variants for ovarian cancer risk modification was identified (top SNP rs10124837, HR: 0.73, 95%CI: 0.68 to 0.79, p-value 2× 10−16). These variants were located up to 20 kb upstream of BNC2. In BRCA2 mutation carriers one region, up to 45 kb upstream of BNC2, and containing 100 correlated SNPs was identified as candidate causal (top SNP rs62543585, HR: 0.69, 95%CI: 0.59 to 0.80, p-value 1.0 × 10−6). The candidate causal in BRCA1 mutation carriers did not include the strongest associated variant at this locus in the general population. In sum, we identified a set of candidate causal variants in a region that encompasses the BNC2 transcription start site. The ovarian cancer association at 9p22.2 may be mediated by different variants in BRCA1 mutation carriers and in the general population. Thus, potentially different mechanisms may underlie ovarian cancer risk for mutation carriers and the general population. PMID:27463617

  4. Fine-Scale Mapping of the FGFR2 Breast Cancer Risk Locus: Putative Functional Variants Differentially Bind FOXA1 and E2F1

    Science.gov (United States)

    Meyer, Kerstin B.; O’Reilly, Martin; Michailidou, Kyriaki; Carlebur, Saskia; Edwards, Stacey L.; French, Juliet D.; Prathalingham, Radhika; Dennis, Joe; Bolla, Manjeet K.; Wang, Qin; de Santiago, Ines; Hopper, John L.; Tsimiklis, Helen; Apicella, Carmel; Southey, Melissa C.; Schmidt, Marjanka K.; Broeks, Annegien; Van ’t Veer, Laura J.; Hogervorst, Frans B.; Muir, Kenneth; Lophatananon, Artitaya; Stewart-Brown, Sarah; Siriwanarangsan, Pornthep; Fasching, Peter A.; Lux, Michael P.; Ekici, Arif B.; Beckmann, Matthias W.; Peto, Julian; dos Santos Silva, Isabel; Fletcher, Olivia; Johnson, Nichola; Sawyer, Elinor J.; Tomlinson, Ian; Kerin, Michael J.; Miller, Nicola; Marme, Federick; Schneeweiss, Andreas; Sohn, Christof; Burwinkel, Barbara; Guénel, Pascal; Truong, Thérèse; Laurent-Puig, Pierre; Menegaux, Florence; Bojesen, Stig E.; Nordestgaard, Børge G.; Nielsen, Sune F.; Flyger, Henrik; Milne, Roger L.; Zamora, M. Pilar; Arias, Jose I.; Benitez, Javier; Neuhausen, Susan; Anton-Culver, Hoda; Ziogas, Argyrios; Dur, Christina C.; Brenner, Hermann; Müller, Heiko; Arndt, Volker; Stegmaier, Christa; Meindl, Alfons; Schmutzler, Rita K.; Engel, Christoph; Ditsch, Nina; Brauch, Hiltrud; Brüning, Thomas; Ko, Yon-Dschun; Nevanlinna, Heli; Muranen, Taru A.; Aittomäki, Kristiina; Blomqvist, Carl; Matsuo, Keitaro; Ito, Hidemi; Iwata, Hiroji; Yatabe, Yasushi; Dörk, Thilo; Helbig, Sonja; Bogdanova, Natalia V.; Lindblom, Annika; Margolin, Sara; Mannermaa, Arto; Kataja, Vesa; Kosma, Veli-Matti; Hartikainen, Jaana M.; Chenevix-Trench, Georgia; Wu, Anna H.; Tseng, Chiu-chen; Van Den Berg, David; Stram, Daniel O.; Lambrechts, Diether; Thienpont, Bernard; Christiaens, Marie-Rose; Smeets, Ann; Chang-Claude, Jenny; Rudolph, Anja; Seibold, Petra; Flesch-Janys, Dieter; Radice, Paolo; Peterlongo, Paolo; Bonanni, Bernardo; Bernard, Loris; Couch, Fergus J.; Olson, Janet E.; Wang, Xianshu; Purrington, Kristen; Giles, Graham G.; Severi, Gianluca; Baglietto, Laura; McLean, Catriona; Haiman, Christopher A.; Henderson, Brian E.; Schumacher, Fredrick; Le Marchand, Loic; Simard, Jacques; Goldberg, Mark S.; Labrèche, France; Dumont, Martine; Teo, Soo-Hwang; Yip, Cheng-Har; Phuah, Sze-Yee; Kristensen, Vessela; Grenaker Alnæs, Grethe; Børresen-Dale, Anne-Lise; Zheng, Wei; Deming-Halverson, Sandra; Shrubsole, Martha; Long, Jirong; Winqvist, Robert; Pylkäs, Katri; Jukkola-Vuorinen, Arja; Kauppila, Saila; Andrulis, Irene L.; Knight, Julia A.; Glendon, Gord; Tchatchou, Sandrine; Devilee, Peter; Tollenaar, Robert A.E.M.; Seynaeve, Caroline M.; García-Closas, Montserrat; Figueroa, Jonine; Chanock, Stephen J.; Lissowska, Jolanta; Czene, Kamila; Darabi, Hartef; Eriksson, Kimael; Hooning, Maartje J.; Martens, John W.M.; van den Ouweland, Ans M.W.; van Deurzen, Carolien H.M.; Hall, Per; Li, Jingmei; Liu, Jianjun; Humphreys, Keith; Shu, Xiao-Ou; Lu, Wei; Gao, Yu-Tang; Cai, Hui; Cox, Angela; Reed, Malcolm W.R.; Blot, William; Signorello, Lisa B.; Cai, Qiuyin; Pharoah, Paul D.P.; Ghoussaini, Maya; Harrington, Patricia; Tyrer, Jonathan; Kang, Daehee; Choi, Ji-Yeob; Park, Sue K.; Noh, Dong-Young; Hartman, Mikael; Hui, Miao; Lim, Wei-Yen; Buhari, Shaik A.; Hamann, Ute; Försti, Asta; Rüdiger, Thomas; Ulmer, Hans-Ulrich; Jakubowska, Anna; Lubinski, Jan; Jaworska, Katarzyna; Durda, Katarzyna; Sangrajrang, Suleeporn; Gaborieau, Valerie; Brennan, Paul; McKay, James; Vachon, Celine; Slager, Susan; Fostira, Florentia; Pilarski, Robert; Shen, Chen-Yang; Hsiung, Chia-Ni; Wu, Pei-Ei; Hou, Ming-Feng; Swerdlow, Anthony; Ashworth, Alan; Orr, Nick; Schoemaker, Minouk J.; Ponder, Bruce A.J.; Dunning, Alison M.; Easton, Douglas F.

    2013-01-01

    The 10q26 locus in the second intron of FGFR2 is the locus most strongly associated with estrogen-receptor-positive breast cancer in genome-wide association studies. We conducted fine-scale mapping in case-control studies genotyped with a custom chip (iCOGS), comprising 41 studies (n = 89,050) of European ancestry, 9 Asian ancestry studies (n = 13,983), and 2 African ancestry studies (n = 2,028) from the Breast Cancer Association Consortium. We identified three statistically independent risk signals within the locus. Within risk signals 1 and 3, genetic analysis identified five and two variants, respectively, highly correlated with the most strongly associated SNPs. By using a combination of genetic fine mapping, data on DNase hypersensitivity, and electrophoretic mobility shift assays to study protein-DNA binding, we identified rs35054928, rs2981578, and rs45631563 as putative functional SNPs. Chromatin immunoprecipitation showed that FOXA1 preferentially bound to the risk-associated allele (C) of rs2981578 and was able to recruit ERα to this site in an allele-specific manner, whereas E2F1 preferentially bound the risk variant of rs35054928. The risk alleles were preferentially found in open chromatin and bound by Ser5 phosphorylated RNA polymerase II, suggesting that the risk alleles are associated with changes in transcription. Chromatin conformation capture demonstrated that the risk region was able to interact with the promoter of FGFR2, the likely target gene of this risk region. A role for FOXA1 in mediating breast cancer susceptibility at this locus is consistent with the finding that the FGFR2 risk locus primarily predisposes to estrogen-receptor-positive disease. PMID:24290378

  5. Tailings philosophies : to segregate or not to segregate

    Energy Technology Data Exchange (ETDEWEB)

    Wells, P.S. [Suncor Energy, Fort McMurray, AB (Canada)

    2010-07-01

    Traditional technologies for treating oil sands tailings include the segregation of of tailings when discharged into water-filled ponds. The coarser tailings form long beaches. However, the percentage of silts and clays that remain suspended within the water column pose significant challenges to oil sands operators, and contribute to water losses and increases in storage volume. This paper discussed new technologies developed to identify the tailings materials that contribute to the problem and methods designed to isolate and treat the materials. Treatment material balances, process water balances, and material handling requirements for the technologies were evaluated and compared. Three scenarios were considered: (1) a sub-aqueous beaching scenario where tailings were produced by extraction and pumped to a beach storage area for dewatering through self-drainage; (2) a non-segregated tailings (NST) scenario that used mature fine tailings (MFT) drying; (3) and a segregated stream scenario where MFT drying was used where tailings were deposited in traditional tailings ponds. Results of the study showed that the segregated stream tailings treatment system was preferred to NST treatment system. Options for sub-aerial NST deposition may overcome the volume discrepancies between treating fines as well as the required volumes of coarser materials. 5 refs., 2 tabs., 2 figs.

  6. Sexual orientation, prejudice and segregation

    NARCIS (Netherlands)

    Plug, E.; Webbink, D.; Martin, N.

    2014-01-01

    This article examines whether gay and lesbian workers sort into tolerant occupations. With information on sexual orientation, prejudice, and occupational choice taken from Australian Twin Registers, we find that gays and lesbians shy away from prejudiced occupations. We show that our segregation res

  7. PICH promotes mitotic chromosome segregation

    DEFF Research Database (Denmark)

    Nielsen, Christian Thomas Friberg; Hickson, Ian D

    2016-01-01

    PICH is an SNF2-family DNA translocase that appears to play a role specifically in mitosis. Characterization of PICH in human cells led to the initial discovery of "ultra-fine DNA bridges" (UFBs) that connect the 2 segregating DNA masses in the anaphase of mitosis. These bridge structures, which...

  8. Nonequilibrium Segregation in Petroleum Reservoirs

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Stenby, Erling Halfdan

    1999-01-01

    We analyse adsorption of a multicomponent mixture at high pressure on the basis of the potential theory of adsorption. The adsorbate is considered as a segregated mixture in the external field produced by a solid adsorbent. we derive an analytical equation for the thickness of a multicomponent fi...

  9. Identification of independent association signals and putative functional variants for breast cancer risk through fine-scale mapping of the 12p11 locus.

    Science.gov (United States)

    Zeng, Chenjie; Guo, Xingyi; Long, Jirong; Kuchenbaecker, Karoline B; Droit, Arnaud; Michailidou, Kyriaki; Ghoussaini, Maya; Kar, Siddhartha; Freeman, Adam; Hopper, John L; Milne, Roger L; Bolla, Manjeet K; Wang, Qin; Dennis, Joe; Agata, Simona; Ahmed, Shahana; Aittomäki, Kristiina; Andrulis, Irene L; Anton-Culver, Hoda; Antonenkova, Natalia N; Arason, Adalgeir; Arndt, Volker; Arun, Banu K; Arver, Brita; Bacot, Francois; Barrowdale, Daniel; Baynes, Caroline; Beeghly-Fadiel, Alicia; Benitez, Javier; Bermisheva, Marina; Blomqvist, Carl; Blot, William J; Bogdanova, Natalia V; Bojesen, Stig E; Bonanni, Bernardo; Borresen-Dale, Anne-Lise; Brand, Judith S; Brauch, Hiltrud; Brennan, Paul; Brenner, Hermann; Broeks, Annegien; Brüning, Thomas; Burwinkel, Barbara; Buys, Saundra S; Cai, Qiuyin; Caldes, Trinidad; Campbell, Ian; Carpenter, Jane; Chang-Claude, Jenny; Choi, Ji-Yeob; Claes, Kathleen B M; Clarke, Christine; Cox, Angela; Cross, Simon S; Czene, Kamila; Daly, Mary B; de la Hoya, Miguel; De Leeneer, Kim; Devilee, Peter; Diez, Orland; Domchek, Susan M; Doody, Michele; Dorfling, Cecilia M; Dörk, Thilo; Dos-Santos-Silva, Isabel; Dumont, Martine; Dwek, Miriam; Dworniczak, Bernd; Egan, Kathleen; Eilber, Ursula; Einbeigi, Zakaria; Ejlertsen, Bent; Ellis, Steve; Frost, Debra; Lalloo, Fiona; Fasching, Peter A; Figueroa, Jonine; Flyger, Henrik; Friedlander, Michael; Friedman, Eitan; Gambino, Gaetana; Gao, Yu-Tang; Garber, Judy; García-Closas, Montserrat; Gehrig, Andrea; Damiola, Francesca; Lesueur, Fabienne; Mazoyer, Sylvie; Stoppa-Lyonnet, Dominique; Giles, Graham G; Godwin, Andrew K; Goldgar, David E; González-Neira, Anna; Greene, Mark H; Guénel, Pascal; Haeberle, Lothar; Haiman, Christopher A; Hallberg, Emily; Hamann, Ute; Hansen, Thomas V O; Hart, Steven; Hartikainen, Jaana M; Hartman, Mikael; Hassan, Norhashimah; Healey, Sue; Hogervorst, Frans B L; Verhoef, Senno; Hendricks, Carolyn B; Hillemanns, Peter; Hollestelle, Antoinette; Hulick, Peter J; Hunter, David J; Imyanitov, Evgeny N; Isaacs, Claudine; Ito, Hidemi; Jakubowska, Anna; Janavicius, Ramunas; Jaworska-Bieniek, Katarzyna; Jensen, Uffe Birk; John, Esther M; Joly Beauparlant, Charles; Jones, Michael; Kabisch, Maria; Kang, Daehee; Karlan, Beth Y; Kauppila, Saila; Kerin, Michael J; Khan, Sofia; Khusnutdinova, Elza; Knight, Julia A; Konstantopoulou, Irene; Kraft, Peter; Kwong, Ava; Laitman, Yael; Lambrechts, Diether; Lazaro, Conxi; Le Marchand, Loic; Lee, Chuen Neng; Lee, Min Hyuk; Lester, Jenny; Li, Jingmei; Liljegren, Annelie; Lindblom, Annika; Lophatananon, Artitaya; Lubinski, Jan; Mai, Phuong L; Mannermaa, Arto; Manoukian, Siranoush; Margolin, Sara; Marme, Frederik; Matsuo, Keitaro; McGuffog, Lesley; Meindl, Alfons; Menegaux, Florence; Montagna, Marco; Muir, Kenneth; Mulligan, Anna Marie; Nathanson, Katherine L; Neuhausen, Susan L; Nevanlinna, Heli; Newcomb, Polly A; Nord, Silje; Nussbaum, Robert L; Offit, Kenneth; Olah, Edith; Olopade, Olufunmilayo I; Olswold, Curtis; Osorio, Ana; Papi, Laura; Park-Simon, Tjoung-Won; Paulsson-Karlsson, Ylva; Peeters, Stephanie; Peissel, Bernard; Peterlongo, Paolo; Peto, Julian; Pfeiler, Georg; Phelan, Catherine M; Presneau, Nadege; Radice, Paolo; Rahman, Nazneen; Ramus, Susan J; Rashid, Muhammad Usman; Rennert, Gad; Rhiem, Kerstin; Rudolph, Anja; Salani, Ritu; Sangrajrang, Suleeporn; Sawyer, Elinor J; Schmidt, Marjanka K; Schmutzler, Rita K; Schoemaker, Minouk J; Schürmann, Peter; Seynaeve, Caroline; Shen, Chen-Yang; Shrubsole, Martha J; Shu, Xiao-Ou; Sigurdson, Alice; Singer, Christian F; Slager, Susan; Soucy, Penny; Southey, Melissa; Steinemann, Doris; Swerdlow, Anthony; Szabo, Csilla I; Tchatchou, Sandrine; Teixeira, Manuel R; Teo, Soo H; Terry, Mary Beth; Tessier, Daniel C; Teulé, Alex; Thomassen, Mads; Tihomirova, Laima; Tischkowitz, Marc; Toland, Amanda E; Tung, Nadine; Turnbull, Clare; van den Ouweland, Ans M W; van Rensburg, Elizabeth J; Ven den Berg, David; Vijai, Joseph; Wang-Gohrke, Shan; Weitzel, Jeffrey N; Whittemore, Alice S; Winqvist, Robert; Wong, Tien Y; Wu, Anna H; Yannoukakos, Drakoulis; Yu, Jyh-Cherng; Pharoah, Paul D P; Hall, Per; Chenevix-Trench, Georgia; Dunning, Alison M; Simard, Jacques; Couch, Fergus J; Antoniou, Antonis C; Easton, Douglas F; Zheng, Wei

    2016-06-21

    Multiple recent genome-wide association studies (GWAS) have identified a single nucleotide polymorphism (SNP), rs10771399, at 12p11 that is associated with breast cancer risk. We performed a fine-scale mapping study of a 700 kb region including 441 genotyped and more than 1300 imputed genetic variants in 48,155 cases and 43,612 controls of European descent, 6269 cases and 6624 controls of East Asian descent and 1116 cases and 932 controls of African descent in the Breast Cancer Association Consortium (BCAC; http://bcac.ccge.medschl.cam.ac.uk/ ), and in 15,252 BRCA1 mutation carriers in the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Stepwise regression analyses were performed to identify independent association signals. Data from the Encyclopedia of DNA Elements project (ENCODE) and the Cancer Genome Atlas (TCGA) were used for functional annotation. Analysis of data from European descendants found evidence for four independent association signals at 12p11, represented by rs7297051 (odds ratio (OR) = 1.09, 95 % confidence interval (CI) = 1.06-1.12; P = 3 × 10(-9)), rs805510 (OR = 1.08, 95 % CI = 1.04-1.12, P = 2 × 10(-5)), and rs1871152 (OR = 1.04, 95 % CI = 1.02-1.06; P = 2 × 10(-4)) identified in the general populations, and rs113824616 (P = 7 × 10(-5)) identified in the meta-analysis of BCAC ER-negative cases and BRCA1 mutation carriers. SNPs rs7297051, rs805510 and rs113824616 were also associated with breast cancer risk at P < 0.05 in East Asians, but none of the associations were statistically significant in African descendants. Multiple candidate functional variants are located in putative enhancer sequences. Chromatin interaction data suggested that PTHLH was the likely target gene of these enhancers. Of the six variants with the strongest evidence of potential functionality, rs11049453 was statistically significantly associated with the expression of PTHLH and its nearby

  10. Evaluation of seabed mapping methods for fine-scale classification of extremely shallow benthic habitats - Application to the Venice Lagoon, Italy

    Science.gov (United States)

    Montereale Gavazzi, G.; Madricardo, F.; Janowski, L.; Kruss, A.; Blondel, P.; Sigovini, M.; Foglini, F.

    2016-03-01

    Recent technological developments of multibeam echosounder systems (MBES) allow mapping of benthic habitats with unprecedented detail. MBES can now be employed in extremely shallow waters, challenging data acquisition (as these instruments were often designed for deeper waters) and data interpretation (honed on datasets with resolution sometimes orders of magnitude lower). With extremely high-resolution bathymetry and co-located backscatter data, it is now possible to map the spatial distribution of fine scale benthic habitats, even identifying the acoustic signatures of single sponges. In this context, it is necessary to understand which of the commonly used segmentation methods is best suited to account for such level of detail. At the same time, new sampling protocols for precisely geo-referenced ground truth data need to be developed to validate the benthic environmental classification. This study focuses on a dataset collected in a shallow (2-10 m deep) tidal channel of the Lagoon of Venice, Italy. Using 0.05-m and 0.2-m raster grids, we compared a range of classifications, both pixel-based and object-based approaches, including manual, Maximum Likelihood Classifier, Jenks Optimization clustering, textural analysis and Object Based Image Analysis. Through a comprehensive and accurately geo-referenced ground truth dataset, we were able to identify five different classes of the substrate composition, including sponges, mixed submerged aquatic vegetation, mixed detritic bottom (fine and coarse) and unconsolidated bare sediment. We computed estimates of accuracy (namely Overall, User, Producer Accuracies and the Kappa statistic) by cross tabulating predicted and reference instances. Overall, pixel based segmentations produced the highest accuracies and the accuracy assessment is strongly dependent on the number of classes chosen for the thematic output. Tidal channels in the Venice Lagoon are extremely important in terms of habitats and sediment distribution

  11. Fine-scale spatial and temporal plankton distributions in the Southern California Bight: lessons from in situ microscopes and broadband echosounders

    Science.gov (United States)

    Briseno-Avena, Christian

    Phytoplankton and zooplankton are important components of marine ecosystems, and play a major role in the biological pump, affecting carbon transport in the global oceans. Their dynamic heterogeneous spatial and temporal distributions require special tools for observing them at the ecological scales relevant to the individual organisms. In this work, I used optic and acoustic methods to study plankton organisms at spatial scales of meters and temporal scales ranging from minutes to months. Using two in situ microscopes I described the fine-scale vertical distribution of phytoplankton and several zooplankton taxa in a coastal location in the Southern California Bight. Highly resolved spatial observations revealed cryptic maxima of fluorescent particles not observed with traditional fluorometers. Furthermore, this high sampling resolution revealed that water density, and not depth, regulated the vertical position, and interactions between observed phytoplankton and zooplankton distributions. Underwater acoustic echosounders can be powerful tools to observe in situ plankton distributions. Interpreting the acoustic echoes, however, requires highly calibrated instruments and ground-truthing experiments to identify the source of acoustic signals. This work presents the description of a novel combination of a broadband, high-frequency (1.5-2.5 MHz) echosounder and a stereoscopic camera --combined, these systems can localize the echo produced by an individual target while simultaneously providing visual identification of the target. This work has provided one of the first comparisons of in situ measured broadband target strength (BTS) and the expected signal using a physical model. The results of this experiment revealed unexpected, important differences between measured and modeled BTS. This system was also used to make in situ observations of individual fragile gelatinous organisms, marine snow particles and phytoplankton, providing evidence of their significant acoustic

  12. 18 CFR 401.113 - Segregable materials.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Segregable materials. 401.113 Section 401.113 Conservation of Power and Water Resources DELAWARE RIVER BASIN COMMISSION... Segregable materials. Any reasonably segregable portion of a record shall be provided to any person...

  13. International perspectives on countering school segregation

    NARCIS (Netherlands)

    Bakker, J.T.A.; Denessen, E.J.P.G.; Peters, T.J.M.; Walraven, G.

    2010-01-01

    School segregation is perceived as an unyielding problem worldwide, which is manifest along both ethnic and socio-economic lines. With this edited volume we aim to share information about school segregation and policies focused on countering school segregation from an international perspective. Many

  14. Bacterial chromosome organization and segregation.

    Science.gov (United States)

    Badrinarayanan, Anjana; Le, Tung B K; Laub, Michael T

    2015-01-01

    If fully stretched out, a typical bacterial chromosome would be nearly 1 mm long, approximately 1,000 times the length of a cell. Not only must cells massively compact their genetic material, but they must also organize their DNA in a manner that is compatible with a range of cellular processes, including DNA replication, DNA repair, homologous recombination, and horizontal gene transfer. Recent work, driven in part by technological advances, has begun to reveal the general principles of chromosome organization in bacteria. Here, drawing on studies of many different organisms, we review the emerging picture of how bacterial chromosomes are structured at multiple length scales, highlighting the functions of various DNA-binding proteins and the impact of physical forces. Additionally, we discuss the spatial dynamics of chromosomes, particularly during their segregation to daughter cells. Although there has been tremendous progress, we also highlight gaps that remain in understanding chromosome organization and segregation.

  15. Bacterial Chromosome Organization and Segregation

    OpenAIRE

    Toro, Esteban; Shapiro, Lucy

    2010-01-01

    Bacterial chromosomes are generally ∼1000 times longer than the cells in which they reside, and concurrent replication, segregation, and transcription/translation of this crowded mass of DNA poses a challenging organizational problem. Recent advances in cell-imaging technology with subdiffraction resolution have revealed that the bacterial nucleoid is reliably oriented and highly organized within the cell. Such organization is transmitted from one generation to the next by progressive segrega...

  16. Habitat degradation may affect niche segregation patterns in lizards

    Science.gov (United States)

    Pelegrin, N.; Chani, J. M.; Echevarria, A. L.; Bucher, E. H.

    2013-08-01

    Lizards partition resources in three main niche dimensions: time, space and food. Activity time and microhabitat use are strongly influenced by thermal environment, and may differ between species according to thermal requirements and tolerance. As thermal characteristics are influenced by habitat structure, microhabitat use and activity of lizards can change in disturbed habitats. We compared activity and microhabitat use of two abundant lizard species of the Semi-arid Chaco of Argentina between a restored and a highly degraded Chaco forest, to determine how habitat degradation affects lizard segregation in time and space, hypothesizing that as activity and microhabitat use of lizards are related to habitat structure, activity and microhabitat use of individual species can be altered in degraded habitats, thus changing segregation patterns between them. Activity changed from an overlapped pattern in a restored forest to a segregated pattern in a degraded forest. A similar trend was observed for microhabitat use, although to a less extent. No correlation was found between air temperature and lizard activity, but lizard activity varied along the day and among sites. Contrary to what was believed, activity patterns of neotropical diurnal lizards are not fixed, but affected by multiple factors related to habitat structure and possibly to interspecific interactions. Changes in activity patterns and microhabitat use in degraded forests may have important implications when analyzing the effects of climate change on lizard species, due to synergistic effects.

  17. Acentrosomal Spindle Assembly & Chromosome Segregation During Oocyte Meiosis

    OpenAIRE

    Dumont, Julien; Desai, Arshad

    2012-01-01

    The ability to reproduce relies in most eukaryotes on specialized cells called gametes. Gametes are formed by the process of meiosis in which, after a single round of replication, two successive cell divisions reduce the ploidy of the genome. Fusion of gametes at fertilization reconstitutes diploidy. In most animal species, chromosome segregation during female meiosis occurs on spindles assembled in the absence of the major microtubule-organizing center, the centrosome. In mammals, oocyte mei...

  18. Proximate drivers of spatial segregation in non-breeding albatrosses.

    Science.gov (United States)

    Clay, Thomas A; Manica, Andrea; Ryan, Peter G; Silk, Janet R D; Croxall, John P; Ireland, Louise; Phillips, Richard A

    2016-07-21

    Many animals partition resources to avoid competition, and in colonially-breeding species this often leads to divergent space or habitat use. During the non-breeding season, foraging constraints are relaxed, yet the patterns and drivers of segregation both between and within populations are poorly understood. We modelled habitat preference to examine how extrinsic (habitat availability and intra-specific competition) and intrinsic factors (population, sex and breeding outcome) influence the distributions of non-breeding grey-headed albatrosses Thalassarche chrysostoma tracked from two major populations, South Georgia (Atlantic Ocean) and the Prince Edward Islands (Indian Ocean). Spatial segregation was greater than expected, reflecting distinct seasonal differences in habitat selection and accessibility, and avoidance of intra-specific competition with local breeders. Previously failed birds segregated spatially from successful birds during summer, when they used less productive waters, suggesting a link between breeding outcome and subsequent habitat selection. In contrast, we found weak evidence of sexual segregation, which did not reflect a difference in habitat use. Our results indicate that the large-scale spatial structuring of albatross distributions results from interactions between extrinsic and intrinsic factors, with important implications for population dynamics. As habitat preferences differed substantially between colonies, populations should be considered independently when identifying critical areas for protection.

  19. Entropy as the driver of chromosome segregation.

    Science.gov (United States)

    Jun, Suckjoon; Wright, Andrew

    2010-08-01

    We present a new physical biology approach to understanding the relationship between the organization and segregation of bacterial chromosomes. We posit that replicated Escherichia coli daughter strands will spontaneously demix as a result of entropic forces, despite their strong confinement within the cell; in other words, we propose that entropy can act as a primordial physical force which drives chromosome segregation under the right physical conditions. Furthermore, proteins implicated in the regulation of chromosome structure and segregation may in fact function primarily in supporting such an entropy-driven segregation mechanism by regulating the physical state of chromosomes. We conclude that bacterial chromosome segregation is best understood in terms of spontaneous demixing of daughter strands. Our concept may also have important implications for chromosome segregation in eukaryotes, in which spindle-dependent chromosome movement follows an extended period of sister chromatid demixing and compaction.

  20. Perceptual-binding and persistent surface segregation

    OpenAIRE

    2004-01-01

    Visual input is segregated in the brain into subsystems that process different attributes such as motion and color. At the same time, visual information is perceptually segregated into objects and surfaces. Here we demonstrate that perceptual segregation of visual entities based on a transparency cue precedes and affects perceptual binding of attributes. Adding an irrelevant transparency cue paradoxically improved the pairing of color and motion for rapidly alternating surfaces. Subsequent ex...

  1. Housing Systems and Ethnic Spatial Segregation

    DEFF Research Database (Denmark)

    Andersen, Hans Skifter; Andersson, Roger; Wessel, Terje

    Residential spatial segregation is related to housing markets and housing policies. In this paper, ethnic segregation is compared across four Nordic capitals and explanations for the differences are examined by comparing the housing markets and housing policies of the countries. The housing markets...... of neighbourhoods. Ethnic segmentation of housing tenures thus contributes to segregation, but the effect is much dependent on how tenures are distributed across space. In one of the cities, the policy of neighbourhood tenure mix has resulted in a relatively low degree of segregation in spite of high concentrations...

  2. Perceptual-binding and persistent surface segregation.

    Science.gov (United States)

    Moradi, Farshad; Shimojo, Shinsuke

    2004-11-01

    Visual input is segregated in the brain into subsystems that process different attributes such as motion and color. At the same time, visual information is perceptually segregated into objects and surfaces. Here we demonstrate that perceptual segregation of visual entities based on a transparency cue precedes and affects perceptual binding of attributes. Adding an irrelevant transparency cue paradoxically improved the pairing of color and motion for rapidly alternating surfaces. Subsequent experiments show: (1) Attributes are registered over the temporal window defined by the perceptual persistence of segregation, resulting in asynchrony in binding, and (2) attention is necessary for correct registration of attributes in the presence of ambiguity.

  3. From particle segregation to the granular clock

    Energy Technology Data Exchange (ETDEWEB)

    Lambiotte, R. [Physique Statistique, Plasmas et Optique Non-lineaire, Universite Libre de Bruxelles, Campus Plaine, Boulevard du Triomphe, Code Postal 231, 1050 Brussels (Belgium)]. E-mail: rlambiot@ulb.ac.be; Salazar, J.M. [Universite De Bougogne-LRRS UMR-5613 CNRS, Faculte des Sciences Mirande, 9 Av. Alain Savary, 21078 Dijon Cedex (France)]. E-mail: jmarcos@u-bourgogne.fr; Brenig, L. [Physique Statistique, Plasmas et Optique Non-lineaire, Universite Libre de Bruxelles, Campus Plaine, Boulevard du Triomphe, Code Postal 231, 1050 Brussels (Belgium)]. E-mail: lbrenig@ulb.ac.be

    2005-08-01

    Recently several authors studied the segregation of particles for a system composed of mono-dispersed inelastic spheres contained in a box divided by a wall in the middle. The system exhibited a symmetry breaking leading to an overpopulation of particles in one side of the box. Here we study the segregation of a mixture of particles composed of inelastic hard spheres and fluidized by a vibrating wall. Our numerical simulations show a rich phenomenology: horizontal segregation and periodic behavior. We also propose an empirical system of ODEs representing the proportion of each type of particles and the segregation flux of particles. These equations reproduce the major features observed by the simulations.

  4. Segregation as Splitting, Segregation as Joining: Schools, Housing, and the Many Modes of Jim Crow

    Science.gov (United States)

    Highsmith, Andrew R.; Erickson, Ansley T.

    2015-01-01

    Popular understandings of segregation often emphasize the Jim Crow South before the 1954 "Brown" decision and, in many instances, explain continued segregation in schooling as the result of segregated housing patterns. The case of Flint, Michigan, complicates these views, at once illustrating the depth of governmental commitment to…

  5. Bulk feeder or selective grazer: African buffalo space use patterns based on fine-scale remotely sensed data on forage quality and quantity

    CSIR Research Space (South Africa)

    Kaszta, Z

    2016-03-01

    Full Text Available The distribution and behaviour of African large grazers are regulated primarily from the bottom up, with some species showing clear preferences for certain vegetation types. While the African buffalo (Syncerus caffer) is sometimes considered a bulk...

  6. Fine-scale linkage mapping reveals a small set of candidate genes influencing honey bee grooming behavior in response to Varroa mites.

    Directory of Open Access Journals (Sweden)

    Miguel E Arechavaleta-Velasco

    Full Text Available Populations of honey bees in North America have been experiencing high annual colony mortality for 15-20 years. Many apicultural researchers believe that introduced parasites called Varroa mites (V. destructor are the most important factor in colony deaths. One important resistance mechanism that limits mite population growth in colonies is the ability of some lines of honey bees to groom mites from their bodies. To search for genes influencing this trait, we used an Illumina Bead Station genotyping array to determine the genotypes of several hundred worker bees at over a thousand single-nucleotide polymorphisms in a family that was apparently segregating for alleles influencing this behavior. Linkage analyses provided a genetic map with 1,313 markers anchored to genome sequence. Genotypes were analyzed for association with grooming behavior, measured as the time that individual bees took to initiate grooming after mites were placed on their thoraces. Quantitative-trait-locus interval mapping identified a single chromosomal region that was significant at the chromosome-wide level (p<0.05 on chromosome 5 with a LOD score of 2.72. The 95% confidence interval for quantitative trait locus location contained only 27 genes (honey bee official gene annotation set 2 including Atlastin, Ataxin and Neurexin-1 (AmNrx1, which have potential neurodevelopmental and behavioral effects. Atlastin and Ataxin homologs are associated with neurological diseases in humans. AmNrx1 codes for a presynaptic protein with many alternatively spliced isoforms. Neurexin-1 influences the growth, maintenance and maturation of synapses in the brain, as well as the type of receptors most prominent within synapses. Neurexin-1 has also been associated with autism spectrum disorder and schizophrenia in humans, and self-grooming behavior in mice.

  7. Ising, Schelling and Self-Organising Segregation

    CERN Document Server

    Stauffer, D

    2007-01-01

    The similarities between phase separation in physics and residential segregation by preference in the Schelling model of 1971 are reviewed. Also, new computer simulations of asymmetric interactions different from the usual Ising model are presented, showing spontaneous magnetisation (= self-organising segregation) and in one case a sharp phase transition.

  8. Ising, Schelling and self-organising segregation

    Science.gov (United States)

    Stauffer, D.; Solomon, S.

    2007-06-01

    The similarities between phase separation in physics and residential segregation by preference in the Schelling model of 1971 are reviewed. Also, new computer simulations of asymmetric interactions different from the usual Ising model are presented, showing spontaneous magnetisation (=self-organising segregation) and in one case a sharp phase transition.

  9. Progressive segregation of the Escherichia coli chromosome

    DEFF Research Database (Denmark)

    Nielsen, Henrik Jørck; Youngren, Brenda; Hansen, Flemming G.

    2006-01-01

    We have followed the fate of 14 different loci around the Escherichia coli chromosome in living cells at slow growth rate using a highly efficient labelling system and automated measurements. Loci are segregated as they are replicated, but with a marked delay. Most markers segregate in a smooth...

  10. On the evolutionary stability of Mendelian segregation.

    Science.gov (United States)

    Ubeda, Francisco; Haig, David

    2005-07-01

    We present a model of a primary locus subject to viability selection and an unlinked locus that causes sex-specific modification of the segregation ratio at the primary locus. If there is a balanced polymorphism at the primary locus, a population undergoing Mendelian segregation can be invaded by modifier alleles that cause sex-specific biases in the segregation ratio. Even though this effect is particularly strong if reciprocal heterozygotes at the primary locus have distinct viabilities, as might occur with genomic imprinting, it also applies if reciprocal heterozygotes have equal viabilities. The expected outcome of the evolution of sex-specific segregation distorters is all-and-none segregation schemes in which one allele at the primary locus undergoes complete drive in spermatogenesis and the other allele undergoes complete drive in oogenesis. All-and-none segregation results in a population in which all individuals are maximally fit heterozygotes. Unlinked modifiers that alter the segregation ratio are unable to invade such a population. These results raise questions about the reasons for the ubiquity of Mendelian segregation.

  11. Measuring segregation: an activity space approach.

    Science.gov (United States)

    Wong, David W S; Shaw, Shih-Lung

    2011-06-01

    While the literature clearly acknowledges that individuals may experience different levels of segregation across their various socio-geographical spaces, most measures of segregation are intended to be used in the residential space. Using spatially aggregated data to evaluate segregation in the residential space has been the norm and thus individual's segregation experiences in other socio-geographical spaces are often de-emphasized or ignored. This paper attempts to provide a more comprehensive approach in evaluating segregation beyond the residential space. The entire activity spaces of individuals are taken into account with individuals serving as the building blocks of the analysis. The measurement principle is based upon the exposure dimension of segregation. The proposed measure reflects the exposure of individuals of a referenced group in a neighborhood to the populations of other groups that are found within the activity spaces of individuals in the referenced group. Using the travel diary data collected from the tri-county area in southeast Florida and the imputed racial-ethnic data, this paper demonstrates how the proposed segregation measurement approach goes beyond just measuring population distribution patterns in the residential space and can provide a more comprehensive evaluation of segregation by considering various socio-geographical spaces.

  12. Losing Ground: School Segregation in Massachuestts

    Science.gov (United States)

    Ayscue, Jennifer B.; Greenberg, Alyssa

    2013-01-01

    Though once a leader in school integration, Massachusetts has regressed over the last two decades as its students of color have experienced intensifying school segregation. This report investigates trends in school segregation in Massachusetts by examining concentration, exposure, and evenness measures by both race and class. First, the report…

  13. Occupational Segregation by Sex: Trends and Prospects.

    Science.gov (United States)

    Blau, Francine D.; Hendricks, Wallace E.

    1979-01-01

    Investigates postwar trends in occupational segregation. Finds segregation increased slightly between 1950-60 as predominantly female clerical/professional jobs increased. Occupation mix changes (1960-70) were neutral in impact, but male inflow into female professions and female inflow into male sales/clerical jobs produced modest segregation…

  14. Chromosome replication and segregation in bacteria.

    Science.gov (United States)

    Reyes-Lamothe, Rodrigo; Nicolas, Emilien; Sherratt, David J

    2012-01-01

    In dividing cells, chromosome duplication once per generation must be coordinated with faithful segregation of newly replicated chromosomes and with cell growth and division. Many of the mechanistic details of bacterial replication elongation are well established. However, an understanding of the complexities of how replication initiation is controlled and coordinated with other cellular processes is emerging only slowly. In contrast to eukaryotes, in which replication and segregation are separate in time, the segregation of most newly replicated bacterial genetic loci occurs sequentially soon after replication. We compare the strategies used by chromosomes and plasmids to ensure their accurate duplication and segregation and discuss how these processes are coordinated spatially and temporally with growth and cell division. We also describe what is known about the three conserved families of ATP-binding proteins that contribute to chromosome segregation and discuss their inter-relationships in a range of disparate bacteria.

  15. The Spatial Context of Residential Segregation

    CERN Document Server

    Roberto, Elizabeth

    2015-01-01

    Scholars have engaged in a longstanding debate about how best to measure residential segregation, and scores of indexes have been developed in response. However, the methods commonly employed are aspatial -- they summarize the characteristics of segregation patterns, such as concentration or clustering, but ignore their spatial features, such as how neighborhoods are spatially arranged. As a consequence, many studies find the same level of segregation whether a city has a patchwork of racial and ethnic enclaves, or is divided into large areas with little or no diversity. New methods have been developed to capture the spatial proximity of neighborhoods and the geographic scale of clustering. However, they lack a realistic measure of distance and do not accurately represent how segregation varies within cities. In this paper, I introduce a new method for studying the spatial context of residential segregation. I measure the distance between locations along city roads rather than in a straight line. Road distanc...

  16. Grain boundary structure and solute segregation in titanium-doped sapphire bicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Seth T.

    2002-05-17

    Solute segregation to ceramic grain boundaries governs material processing and microstructure evolution, and can strongly influence material properties critical to engineering performance. Understanding the evolution and implications of grain boundary chemistry is a vital component in the greater effort to engineer ceramics with controlled microstructures. This study examines solute segregation to engineered grain boundaries in titanium-doped sapphire (Al2O3) bicrystals, and explores relationships between grain boundary structure and chemistry at the nanometer scale using spectroscopic and imaging techniques in the transmission electron microscope (TEM). Results demonstrate dramatic changes in solute segregation stemming from small fluctuations in grain boundary plane and structure. Titanium and silicon solute species exhibit strong tendencies to segregate to non-basal and basal grain boundary planes, respectively. Evidence suggests that grain boundary faceting occurs in low-angle twis t boundaries to accommodate nonequilibrium solute segregation related to slow specimen cooling rates, while faceting of tilt grain boundaries often occurs to expose special planes of the coincidence site lattice (CSL). Moreover, quantitative analysis of grain boundary chemistry indicates preferential segregation of charged defects to grain boundary dislocations. These results offer direct proof that static dislocations in ionic materials can assume a net charge, and emphasize the importance of interactions between charged point, line, and planar defects in ionic materials. Efforts to understand grain boundary chemistry in terms of space charge theory, elastic misfit and nonequilibrium segregation are discussed for the Al2O3 system.

  17. Modeling density segregation in granular flow

    Science.gov (United States)

    Xiao, Hongyi; Lueptow, Richard; Umbanhowar, Paul

    2015-11-01

    A recently developed continuum-based model accurately predicts segregation in flows of granular mixtures varying in particle size by considering the interplay of advection, diffusion and segregation. In this research, we extend the domain of the model to include density driven segregation. Discrete Element Method (DEM) simulations of density bidisperse flows of mono-sized particles in a quasi-2D bounded heap were performed to determine the dependence of the density driven segregation velocity on local shear rate, particle concentration, and a segregation length which scales with the particle size and the logarithm of the density ratio. With these inputs, the model yields theoretical predictions of density segregation patterns that quantitatively match the DEM simulations over a range of density ratios (1.11-3.33) and flow rates (19.2-113.6 cm3/s). Matching experiments with various combinations of glass, steel and ceramic particles were also performed which reproduced the segregation patterns obtained in both the simulations and the theory.

  18. Fine-scale genetic mapping of a hybrid sterility factor between Drosophila simulans and D. mauritiana: the varied and elusive functions of "speciation genes"

    Directory of Open Access Journals (Sweden)

    Lemos Bernardo

    2010-12-01

    Full Text Available Abstract Background Hybrid male sterility (HMS is a usual outcome of hybridization between closely related animal species. It arises because interactions between alleles that are functional within one species may be disrupted in hybrids. The identification of genes leading to hybrid sterility is of great interest for understanding the evolutionary process of speciation. In the current work we used marked P-element insertions as dominant markers to efficiently locate one genetic factor causing a severe reduction in fertility in hybrid males of Drosophila simulans and D. mauritiana. Results Our mapping effort identified a region of 9 kb on chromosome 3, containing three complete and one partial coding sequences. Within this region, two annotated genes are suggested as candidates for the HMS factor, based on the comparative molecular characterization and public-source information. Gene Taf1 is partially contained in the region, but yet shows high polymorphism with four fixed non-synonymous substitutions between the two species. Its molecular functions involve sequence-specific DNA binding and transcription factor activity. Gene agt is a small, intronless gene, whose molecular function is annotated as methylated-DNA-protein-cysteine S-methyltransferase activity. High polymorphism and one fixed non-synonymous substitution suggest this is a fast evolving gene. The gene trees of both genes perfectly separate D. simulans and D. mauritiana into monophyletic groups. Analysis of gene expression using microarray revealed trends that were similar to those previously found in comparisons between whole-genome hybrids and parental species. Conclusions The identification following confirmation of the HMS candidate gene will add another case study leading to understanding the evolutionary process of hybrid incompatibility.

  19. Land planarians (Platyhelminthes) as a model organism for fine-scale phylogeographic studies: understanding patterns of biodiversity in the Brazilian Atlantic Forest hotspot.

    Science.gov (United States)

    Alvarez-Presas, M; Carbayo, F; Rozas, J; Riutort, M

    2011-04-01

    The Brazilian Atlantic Forest is one of the richest biodiversity hotspots of the world. Paleoclimatic models have predicted two large stability regions in its northern and central parts, whereas southern regions might have suffered strong instability during Pleistocene glaciations. Molecular phylogeographic and endemism studies show, nevertheless, contradictory results: although some results validate these predictions, other data suggest that paleoclimatic models fail to predict stable rainforest areas in the south. Most studies, however, have surveyed species with relatively high dispersal rates whereas taxa with lower dispersion capabilities should be better predictors of habitat stability. Here, we have used two land planarian species as model organisms to analyse the patterns and levels of nucleotide diversity on a locality within the Southern Atlantic Forest. We find that both species harbour high levels of genetic variability without exhibiting the molecular footprint of recent colonization or population expansions, suggesting a long-term stability scenario. The results reflect, therefore, that paleoclimatic models may fail to detect refugia in the Southern Atlantic Forest, and that model organisms with low dispersal capability can improve the resolution of these models. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

  20. Mechanical Transgressive Segregation and the Rapid Origin of Trophic Novelty

    Science.gov (United States)

    Holzman, Roi; Hulsey, C. Darrin

    2017-01-01

    Hybrid phenotypes are often intermediate between those of parental species. However, hybridization can generate novel phenotypes when traits are complex. For instance, even when the morphologies of individual musculo-skeletal components do not segregate outside the parental range in hybrid offspring, complex functional systems can exhibit emergent phenotypes whose mechanics exceed the parental values. To determine if transgression in mechanics could facilitate divergence during an adaptive radiation, we examined three functional systems in the trophic apparatus of Lake Malawi cichlid fishes. We conducted a simulation study of hybridization between species pairs whose morphology for three functional systems was empirically measured, to determine how the evolutionary divergence of parental species influences the frequency that hybridization could produce mechanics that transgress the parental range. Our simulations suggest that the complex mechanical systems of the cichlid trophic apparatus commonly exhibit greater transgression between more recently diverged cichlid species. Because (1) all three mechanical systems produce hybrids with transgressive mechanics in Lake Malawi cichlids, (2) hybridization is common, and (3) single hybrid crosses often recapitulate a substantial diversity of mechanics, we conclude that mechanical transgressive segregation could play an important role in the rapid accumulation of phenotypic variation in adaptive radiations. PMID:28079133

  1. Veil: A Wall of Segregation

    Directory of Open Access Journals (Sweden)

    Tayebeh Nowrouzi

    2015-08-01

    Full Text Available Moving behind the confines of the race has been the continuous efforts of African-Americans so as to reveal and confirm their true humanity and abilities to white race as well as their own race. African-Americans, Dubois posited, are shut out of the white America, inhabiting behind a vast veil which creates a deep division between the races. Veil is made of the fabric of racism interwoven thread by thread and imposed by white world. It is thrown discourteously and forcibly to the African-Americans whom their distorted images are imposed on them and their true humanity and identity are hidden behind the veil. This study overtakes to present how Loraine Hansberry, in her first and the most outstanding drama, A Raisin in the Sun examines the world within the veil. She demonstrated that Duboisian metaphoric veil is operating in the racist American society so that not only African-Americans are segregated physically and psychologically from the rest of the world but also are inflicted with obscurity of vision that are neither able to see themselves clearly nor be seen truly. On the other hand, it presents how the veil provides blacks with the second sight to observe and comprehend the racist nature of whites which is hidden and incomprehensible for them.

  2. Genes that bias Mendelian segregation.

    Directory of Open Access Journals (Sweden)

    Pierre Grognet

    Full Text Available Mendel laws of inheritance can be cheated by Meiotic Drive Elements (MDs, complex nuclear genetic loci found in various eukaryotic genomes and distorting segregation in their favor. Here, we identify and characterize in the model fungus Podospora anserina Spok1 and Spok2, two MDs known as Spore Killers. We show that they are related genes with both spore-killing distorter and spore-protecting responder activities carried out by the same allele. These alleles act as autonomous elements, exert their effects independently of their location in the genome and can act as MDs in other fungi. Additionally, Spok1 acts as a resistance factor to Spok2 killing. Genetical data and cytological analysis of Spok1 and Spok2 localization during the killing process suggest a complex mode of action for Spok proteins. Spok1 and Spok2 belong to a multigene family prevalent in the genomes of many ascomycetes. As they have no obvious cellular role, Spok1 and Spok2 Spore Killer genes represent a novel kind of selfish genetic elements prevalent in fungal genome that proliferate through meiotic distortion.

  3. Genes that bias Mendelian segregation.

    Science.gov (United States)

    Grognet, Pierre; Lalucque, Hervé; Malagnac, Fabienne; Silar, Philippe

    2014-01-01

    Mendel laws of inheritance can be cheated by Meiotic Drive Elements (MDs), complex nuclear genetic loci found in various eukaryotic genomes and distorting segregation in their favor. Here, we identify and characterize in the model fungus Podospora anserina Spok1 and Spok2, two MDs known as Spore Killers. We show that they are related genes with both spore-killing distorter and spore-protecting responder activities carried out by the same allele. These alleles act as autonomous elements, exert their effects independently of their location in the genome and can act as MDs in other fungi. Additionally, Spok1 acts as a resistance factor to Spok2 killing. Genetical data and cytological analysis of Spok1 and Spok2 localization during the killing process suggest a complex mode of action for Spok proteins. Spok1 and Spok2 belong to a multigene family prevalent in the genomes of many ascomycetes. As they have no obvious cellular role, Spok1 and Spok2 Spore Killer genes represent a novel kind of selfish genetic elements prevalent in fungal genome that proliferate through meiotic distortion.

  4. A Social Network Analysis of Occupational Segregation

    DEFF Research Database (Denmark)

    Buhai, Ioan Sebastian; van der Leij, Marco

    We develop a social network model of occupational segregation between different social groups, generated by the existence of positive inbreeding bias among individuals from the same group. If network referrals are important for job search, then expected homophily in the contact network structure...... induces different career choices for individuals from different social groups. This further translates into stable occupational segregation equilibria in the labor market. We derive the conditions for wage and unemployment inequality in the segregation equilibria and characterize first and second best...

  5. Segregation of Polymers in Confined Spaces

    CERN Document Server

    Liu, Ya

    2009-01-01

    We investigate the motion of two overlapping polymers with self-avoidance confined in a narrow 2d box. A statistical model is constructed using blob free-energy arguments. We find spontaneous segregation under the condition: $L > R_{//}$, and mixing under $L < R_{//}$, where L is the length of the box, and $R_{//}$ the polymer extension in an infinite slit. Segregation time scales are determined by solving a mean first-passage time problem, and by performing Monte Carlo simulations. Predictions of the two methods show good agreement. Our results may elucidate a driving force for chromosomes segregation in bacteria.

  6. Differences in fine-scale genetic structure and dispersal in Quercus ilex L. and Q. suber L.: consequences for regeneration of mediterranean open woods.

    Science.gov (United States)

    Soto, A; Lorenzo, Z; Gil, L

    2007-12-01

    Cork oak (Quercus suber L.) and holm oak (Q. ilex L.) are among the most important tree species (economically and ecologically) in the Western Mediterranean region, where they define unique open woods (created and maintained by man) known as 'dehesas' in Spain. However, these formations are under increasing threat due to the lack of regeneration. We have analysed spatial genetic structure in a mixed parkland; inferences about gene dispersal have also been performed, according to the isolation by distance model. Noticeable differences have been detected between the species, despite their similar ecological roles. Restricted effective dispersal leads to kin structures in cork oak, up to 70 m, while no genetic structure is observed in holm oak. Our results suggest a very effective dispersal for the latter, with a local historical gene flow estimated between 55 and 95 m. This is the first time regeneration of Mediterranean oak parklands has been assessed from a genetic perspective. Effective gene flow detected for holm oaks allows us to discount the risk of inbreeding over successive generations. Thus, regeneration of Q. ilex dehesas will just require action directed to help the settlement of the saplings (such as limiting grazing). However, in those cases where densities are too low, more intense forestation (such as plantation and/or establishment of appropriate shelter) will be needed. The 'density threshold' for initiating regeneration will probably be higher for cork oak, due to its more limited dispersal and minor full-light tolerance.

  7. Possible segregation caused by centrifugal titanium casting.

    Science.gov (United States)

    Watanabe, K; Okawa, S; Kanatani, M; Nakano, S; Miyakawa, O; Kobayashi, M

    1996-12-01

    The possibility of the segregation under solidification process using a centrifugal casting machine was investigated using an electron probe microanalyzer with elemental distribution map, line analysis and quantitative analysis. When a very small quantity of platinum was added to local molten titanium during the casting process, macroscopic segregation was observed under conditions of density difference of 0.1 g/cm3 at the most, confirming that the centrifugal force of the casting machine is extremely strong. When a Ti-6Al-4V alloy was cast, however, no macroscopic segregation was observed. The centrifugal force of the casting machine examined in the present study hardly results in the body-force segregation in this titanium alloy.

  8. Entropy as the driver of chromosome segregation

    OpenAIRE

    Jun, Suckjoon; Wright, Andrew

    2010-01-01

    We present a new physical biology approach to understanding the relationship between the organization and segregation of bacterial chromosomes. We posit that replicated Escherichia coli daughter strands will spontaneously demix as a result of entropic forces, despite their strong confinement within the cell; in other words, we propose that entropy can act as a primordial physical force which drives chromosome segregation under the right physical conditions. Furthermore, proteins implicated in...

  9. Transport analogy for segregation and granular rheology

    Science.gov (United States)

    Liu, Siying; McCarthy, Joseph J.

    2017-08-01

    Here, we show a direct connection between density-based segregation and granular rheology that can lead to insight into both problems. Our results exhibit a transition in the rate of segregation during simple shear that occurs at I ˜0.5 and mimics a coincident regime change in flow rheology. We propose scaling arguments that support a packing fraction criterion for this transition that can both explain our segregation results as well as unify existing literature studies of granular rheology. By recasting a segregation model in terms of rheological parameters, we establish an approach that not only collapses results for a wide range of conditions, but also yields a direct relationship between the coordination number z and the segregation velocity. Moreover, our approach predicts the precise location of the observed regime change or saturation. This suggests that it is possible to rationally design process operating conditions that lead to significantly lower segregation extents. These observations can have a profound impact on both the study of granular flow or mixing as well as industrial practice.

  10. Acentrosomal spindle assembly and chromosome segregation during oocyte meiosis.

    Science.gov (United States)

    Dumont, Julien; Desai, Arshad

    2012-05-01

    The ability to reproduce relies in most eukaryotes on specialized cells called gametes. Gametes are formed by the process of meiosis in which, after a single round of replication, two successive cell divisions reduce the ploidy of the genome. Fusion of gametes at fertilization reconstitutes diploidy. In most animal species, chromosome segregation during female meiosis occurs on spindles assembled in the absence of the major microtubule-organizing center, the centrosome. In mammals, oocyte meiosis is error prone and underlies most birth aneuploidies. Here, we review recent work on acentrosomal spindle formation and chromosome alignment/separation during oocyte meiosis in different animal models.

  11. Gender Segregation in the Spanish Labor Market: An Alternative Approach

    Science.gov (United States)

    del Rio, Coral; Alonso-Villar, Olga

    2010-01-01

    The aim of this paper is to study occupational segregation by gender in Spain, which is a country where occupational segregation explains a large part of the gender wage gap. As opposed to previous studies, this paper measures not only overall segregation, but also the segregation of several population subgroups. For this purpose, this paper uses…

  12. Fine-scale genetic characterization of Plasmodium falciparum chromosome 7 encompassing the antigenic var and the drug-resistant pfcrt genes

    Indian Academy of Sciences (India)

    Ruchi Bajaj; Sujata Mohanty; A. P. Dash; Aparup Das

    2008-04-01

    The fact that malaria is still an uncontrolled disease is reflected by the genetic organization of the parasite genome. Efforts to curb malaria should begin with proper understanding of the mechanism by which the parasites evade human immune system and evolve resistance to different antimalarial drugs. We have initiated such a study and presented herewith the results from the in silico understanding of a seventh chromosomal region of the malarial parasite Plasmodium falciparum encompassing the antigenic var genes (coding pfemp1) and the drug-resistant gene pfcrt located at a specified region of the chromosome 7. We found 60 genes of various functions and lengths, majority (61.67%) of them were performing known functions. Almost all the genes have orthologs in other four species of Plasmodium, of which P. chabaudi seems to be the closest to P. falciparum. However, only two genes were found to be paralogous. Interestingly, the drug-resistant gene, pfcrt was found to be surrounded by seven genes coding for several CG proteins out of which six were reported to be responsible for providing drug resistance to P. vivax. The intergenic regions, in this specified region were generally large in size, majority (73%) of them were of more than 500 nucleotide bp length. We also designed primers for amplification of 21 noncoding DNA fragments in the whole region for estimating genetic diversity and inferring the evolutionary history of this region of P. falciparum genome.

  13. Does prey capture induce area-restricted search? A fine-scale study using GPS in a marine predator, the wandering albatross.

    Science.gov (United States)

    Weimerskirch, Henri; Pinaud, David; Pawlowski, Frédéric; Bost, Charles-André

    2007-11-01

    In a patchy environment, predators are expected to increase turning rate and start an area-restricted search (ARS) when prey have been encountered, but few empirical data exist for large predators. By using GPS loggers with devices measuring prey capture, we studied how a marine predator adjusts foraging movements at various scales in relation to prey capture. Wandering albatrosses use two tactics, sit and wait and foraging in flight, the former tactic being three times less efficient than the latter. During flight foraging, birds caught large isolated prey and used ARS at scales varying from 5 to 90 km, with large-scale ARS being used only by young animals. Birds did not show strong responses to prey capture at a large scale, few ARS events occurred after prey capture, and birds did not have high rates of prey capture in ARS. Only at small scales did birds increase sinuosity after prey captures for a limited time period, and this occurred only after they had caught a large prey item within an ARS zone. When this species searches over a large scale, the most effective search rule was to follow a nearly straight path. ARS may be used to restrict search to a particular environment where prey capture is more predictable and profitable.

  14. Landscape determinants of fine-scale genetic structure of a small rodent in a heterogeneous landscape (Hluhluwe-iMfolozi Park, South Africa).

    Science.gov (United States)

    Russo, Isa-Rita M; Sole, Catherine L; Barbato, Mario; von Bramann, Ullrich; Bruford, Michael W

    2016-07-13

    Small mammals provide ecosystem services, acting, for example, as pollinators and seed dispersers. In addition, they are also disease reservoirs that can be detrimental to human health and they can also act as crop pests. Knowledge of their dispersal preferences is therefore useful for population management and landscape planning. Genetic data were used alongside landscape data to examine the influence of the landscape on the demographic connectedness of the Natal multimammate mouse (Mastomys natalensis) and to identify landscape characteristics that influence the genetic structure of this species across a spatially and temporally varying environment. The most significant landscape features shaping gene flow were aspect, vegetation cover, topographic complexity (TC) and rivers, with western facing slopes, topographic complexity and rivers restricting gene flow. In general, thicket vegetation was correlated with increased gene flow. Identifying features of the landscape that facilitate movement/dispersal in M. natalensis potentially has application for other small mammals in similar ecosystems. As the primary reservoir host of the zoonotic Lassa virus, a landscape genetics approach may have applications in determining areas of high disease risk to humans. Identifying these landscape features may also be important in crop management due to damage by rodent pests.

  15. Continuous utility factor in segregation models

    Science.gov (United States)

    Roy, Parna; Sen, Parongama

    2016-02-01

    We consider the constrained Schelling model of social segregation in which the utility factor of agents strictly increases and nonlocal jumps of the agents are allowed. In the present study, the utility factor u is defined in a way such that it can take continuous values and depends on the tolerance threshold as well as the fraction of unlike neighbors. Two models are proposed: in model A the jump probability is determined by the sign of u only, which makes it equivalent to the discrete model. In model B the actual values of u are considered. Model A and model B are shown to differ drastically as far as segregation behavior and phase transitions are concerned. In model A, although segregation can be achieved, the cluster sizes are rather small. Also, a frozen state is obtained in which steady states comprise many unsatisfied agents. In model B, segregated states with much larger cluster sizes are obtained. The correlation function is calculated to show quantitatively that larger clusters occur in model B. Moreover for model B, no frozen states exist even for very low dilution and small tolerance parameter. This is in contrast to the unconstrained discrete model considered earlier where agents can move even when utility remains the same. In addition, we also consider a few other dynamical aspects which have not been studied in segregation models earlier.

  16. Racial Segregation and the American Foreclosure Crisis.

    Science.gov (United States)

    Rugh, Jacob S; Massey, Douglas S

    2010-10-01

    Although the rise in subprime lending and the ensuing wave of foreclosures was partly a result of market forces that have been well-identified in the literature, in the United States it was also a highly racialized process. We argue that residential segregation created a unique niche of poor minority clients who were differentially marketed risky subprime loans that were in great demand for use in mortgage-backed securities that could be sold on secondary markets. We test this argument by regressing foreclosure actions in the top 100 U.S. metropolitan areas on measures of black, Hispanic, and Asian segregation while controlling for a variety of housing market conditions, including average creditworthiness, the extent of coverage under the Community Reinvestment Act, the degree of zoning regulation, and the overall rate of subprime lending. We find that black residential dissimilarity and spatial isolation are powerful predictors of foreclosures across U.S. metropolitan areas. In order to isolate subprime lending as the causal mechanism whereby segregation influences foreclosures, we estimate a two-stage least squares model that confirms the causal effect of black segregation on the number and rate of foreclosures across metropolitan areas. In the United States segregation was an important contributing cause of the foreclosure crisis, along with overbuilding, risky lending practices, lax regulation, and the bursting of the housing price bubble.

  17. Neurotransmitter segregation: functional and plastic implications.

    Science.gov (United States)

    Sámano, Cynthia; Cifuentes, Fredy; Morales, Miguel Angel

    2012-06-01

    Synaptic cotransmission is the ability of neurons to use more than one transmitter to convey synaptic signals. Cotransmission was originally described as the presence of a classic transmitter, which conveys main signal, along one or more cotransmitters that modulate transmission, later on, it was found cotransmission of classic transmitters. It has been generally accepted that neurons store and release the same set of transmitters in all their synaptic processes. However, some findings that show axon endings of individual neurons storing and releasing different sets of transmitters, are not in accordance with this assumption, and give support to the hypothesis that neurons can segregate transmitters to different synapses. Here, we review the studies showing segregation of transmitters in invertebrate and mammalian central nervous system neurons, and correlate them with our results obtained in sympathetic neurons. Our data show that these neurons segregate even classic transmitters to separated axons. Based on our data we suggest that segregation is a plastic phenomenon and responds to functional synaptic requirements, and to 'environmental' cues such as neurotrophins. We propose that neurons have the machinery to guide the different molecules required in synaptic transmission through axons and sort them to different axon endings. We believe that transmitter segregation improves neuron interactions during cotransmission and gives them selective and better control of synaptic plasticity.

  18. Segregation of Niobium During Electroslag Remelting Process

    Institute of Scientific and Technical Information of China (English)

    DONG Yan-wu; JIANG Zhou-hua; LI Zheng-bang

    2009-01-01

    Experiment was carried out after the process parameters were calculated by the model previously established.The relationship between interdendritic spacing and local solidification time (LST) mainly determined by process parameters was exposed.Furthermore,the extent of segregation was studied.The results indicate that LST and interdendritic spacing are the largest and the amount of Laves phase as a result of the niobium segregation is the highest in the center of the ingot,whereas the opposite results are obtained at the edge of ingot.The extent of element segregation and the amount of Laves phase can be reduced when appropriate parameters are used.Therefore,the duration of subsequent homogenization treatments for 718 is shortened and the alloy quality is improved.

  19. School Segregation and Racial Academic Achievement Gaps

    Directory of Open Access Journals (Sweden)

    Sean F. Reardon

    2016-09-01

    Full Text Available Although it is clear that racial segregation is linked to academic achievement gaps, the mechanisms underlying this link have been debated since James Coleman published his eponymous 1966 report. In this paper, I examine sixteen distinct measures of segregation to determine which is most strongly associated with academic achievement gaps. I find clear evidence that one aspect of segregation in particular—the disparity in average school poverty rates between white and black students’ schools—is consistently the single most powerful correlate of achievement gaps, a pattern that holds in both bivariate and multivariate analyses. This implies that high-poverty schools are, on average, much less effective than lower-poverty schools and suggests that strategies that reduce the differential exposure of black, Hispanic, and white students to poor schoolmates may lead to meaningful reductions in academic achievement gaps.

  20. Segregating complex sound sources through temporal coherence.

    Directory of Open Access Journals (Sweden)

    Lakshmi Krishnan

    2014-12-01

    Full Text Available A new approach for the segregation of monaural sound mixtures is presented based on the principle of temporal coherence and using auditory cortical representations. Temporal coherence is the notion that perceived sources emit coherently modulated features that evoke highly-coincident neural response patterns. By clustering the feature channels with coincident responses and reconstructing their input, one may segregate the underlying source from the simultaneously interfering signals that are uncorrelated with it. The proposed algorithm requires no prior information or training on the sources. It can, however, gracefully incorporate cognitive functions and influences such as memories of a target source or attention to a specific set of its attributes so as to segregate it from its background. Aside from its unusual structure and computational innovations, the proposed model provides testable hypotheses of the physiological mechanisms of this ubiquitous and remarkable perceptual ability, and of its psychophysical manifestations in navigating complex sensory environments.

  1. Transition between segregation and aggregation: the role of environmental constraints.

    Science.gov (United States)

    Nicolis, Stamatios C; Halloy, José; Deneubourg, Jean-Louis

    2016-09-07

    Interactions between sub-groups (species, strains) have been reported in many species among many taxae. We propose a generic model based on earlier experiments accounting for both conspecific (or between individuals of the same strains) and heterospecific (or between strains) interactions. The model predicts different collective behaviours without any change of individuals' algorithm as some key generic parameters such as the carrying capacity, the number of individuals involved and the strength of inter-attraction between sub-groups are varied. A key result is the possibility for sub-groups to segregate between patches and for transition between different patterns, even in absence of active agonistic behaviour. The model can be viewed as a network of feedbacks that is independent of the signals or cues involved in mixed groups interactions. Its predictions are therefore applicable to a wide spectrum of situations including social insects (inter castes interaction) and provides insights on possible mechanisms that can be at work.

  2. Chemical segregation and self polarisation in ferroelectrics

    Directory of Open Access Journals (Sweden)

    Bernard E. Watts

    2009-06-01

    Full Text Available Chemical partitioning or segregation is commonly encountered in solid-state syntheses. It is driven by compositional, thermal and electric field gradients. These phenomena can be quite extreme in thin films and lead to notable effects on the electrical properties of ferroelectrics. The segregation in ferroelectric thin films will be illustrated and the mechanisms explained in terms of diffusion processes driven by a potential gradient of the oxygen. The hypothesis can also explain self polarisation and imprint in ferroelectric hysteresis.

  3. Housing Systems and Ethnic Spatial Segregation

    DEFF Research Database (Denmark)

    Andersen, Hans Skifter; Andersson, Roger; Wessel, Terje

    in Denmark, Finland, Norway and Sweden are ethnically segmented with high concentrations of immigrants in some forms of tenures (especially social/public housing) and low concentrations in others. The paper shows that the spatial distribution of immigrants is strongly connected with the tenure composition...... of immigrants in social/public housing.......Residential spatial segregation is related to housing markets and housing policies. In this paper, ethnic segregation is compared across four Nordic capitals and explanations for the differences are examined by comparing the housing markets and housing policies of the countries. The housing markets...

  4. Flow and segregation in sheared granular slurries

    Science.gov (United States)

    Barentin, C.; Azanza, E.; Pouligny, B.

    2004-04-01

    We study the behaviour of a granular slurry, i.e., a very concentrated suspension of heavy (denser than the fluid) and polydisperse particles sheared between two parallel-plane circular disks. For small gaps, the slurry behaves as a 2d system with a characteristic radial size segregation of particles. For large gaps, the slurry responds as a 3d system, with considerable vertical segregation and a concomitant 2-phase (fluid, solid) flow structure. The thickness ζ of the fluid phase is the 2d-3d gap crossover. Surprisingly, ζ is found to be nearly unaffected by very large changes in the particle size distribution.

  5. Analyzing the proximity to cover in a landscape of fear: a new approach applied to fine-scale habitat use by rabbits facing feral cat predation on Kerguelen archipelago

    Directory of Open Access Journals (Sweden)

    Pierrick Blanchard

    2016-03-01

    Full Text Available Although proximity to cover has been routinely considered as an explanatory variable in studies investigating prey behavioral adjustments to predation pressure, the way it shapes risk perception still remains equivocal. This paradox arises from both the ambivalent nature of cover as potentially both obstructive and protective, making its impact on risk perception complex and context-dependent, and from the choice of the proxy used to measure proximity to cover in the field, which leads to an incomplete picture of the landscape of fear experienced by the prey. Here, we study a simple predator-prey-habitat system, i.e., rabbits Oryctolagus cuniculus facing feral cat Felis catus predation on Kerguelen archipelago. We assess how cover shapes risk perception in prey and develop an easily implementable field method to improve the estimation of proximity to cover. In contrast to protocols considering the “distance to nearest cover”, we focus on the overall “area to cover”. We show that fine-scale habitat use by rabbits is clearly related to our measure, in accordance with our hypothesis of higher risk in patches with smaller area to cover in this predator-prey-habitat system. In contrast, classical measures of proximity to cover are not retained in the best predictive models of habitat use. The use of this new approach, together with a more in-depth consideration of contrasting properties of cover, could help to better understand the role of this complex yet decisive parameter for predator-prey ecology.

  6. Reconstruction of Fine Scale Auroral Dynamics

    CERN Document Server

    Hirsch, Michael; Zettergren, Matthew; Dahlgren, Hanna; Goenka, Chhavi; Akbari, Hassanali

    2015-01-01

    We present a feasibility study for a high frame rate, short baseline auroral tomographic imaging system useful for estimating parametric variations in the precipitating electron number flux spectrum of dynamic auroral events. Of particular interest are auroral substorms, characterized by spatial variations of order 100 m and temporal variations of order 10 ms. These scales are thought to be produced by dispersive Alfv\\'en waves in the near-Earth magnetosphere. The auroral tomography system characterized in this paper reconstructs the auroral volume emission rate to estimate the characteristic energy and location in the direction perpendicular to the geomagnetic field of peak electron precipitation flux using a distributed network of precisely synchronized ground-based cameras. As the observing baseline decreases, the tomographic inverse problem becomes highly ill-conditioned; as the sampling rate increases, the signal-to-noise ratio degrades and synchronization requirements become increasingly critical. Our a...

  7. Genetic architecture of male sterility and segregation distortion in Drosophila pseudoobscura Bogota-USA hybrids.

    Science.gov (United States)

    Phadnis, Nitin

    2011-11-01

    Understanding the genetic basis of reproductive isolation between recently diverged species is a central problem in evolutionary genetics. Here, I present analyses of the genetic architecture underlying hybrid male sterility and segregation distortion between the Bogota and USA subspecies of Drosophila pseudoobscura. Previously, a single gene, Overdrive (Ovd), was shown to be necessary but not sufficient for both male sterility and segregation distortion in F(1) hybrids between these subspecies, requiring several interacting partner loci for full manifestation of hybrid phenomena. I map these partner loci separately on the Bogota X chromosome and USA autosomes using a combination of different mapping strategies. I find that hybrid sterility involves a single hybrid incompatibility of at least seven interacting partner genes that includes three large-effect loci. Segregation distortion involves three loci on the Bogota X chromosome and one locus on the autosomes. The genetic bases of hybrid sterility and segregation distortion are at least partially--but not completely--overlapping. My results lay the foundation for fine-mapping experiments to identify the complete set of genes that interact with Overdrive. While individual genes that cause hybrid sterility or inviability have been identified in a few cases, my analysis provides a comprehensive look at the genetic architecture of all components of a hybrid incompatibility underlying F(1) hybrid sterility. Such an analysis would likely be unfeasible for most species pairs due to their divergence time and emphasizes the importance of young species pairs such as the D. pseudoobscura subspecies studied here.

  8. A Social Network Analysis of Occupational Segregation

    DEFF Research Database (Denmark)

    Buhai, Ioan Sebastian; van der Leij, Marco

    We develop a social network model of occupational segregation between different social groups, generated by the existence of positive inbreeding bias among individuals from the same group. If network referrals are important for job search, then expected homophily in the contact network structure...

  9. Field induced phase segregation in ferrofluids

    NARCIS (Netherlands)

    Kooij, Ernst S.; Galca, A.C.; Poelsema, Bene

    2008-01-01

    We study the phase segregation in magnetite ferrofluids under the influence of an external magnetic field. A phase with lower nanoparticle density and corresponding higher optical transmission is formed in the bottom of a glass cell in the presence of only a very modest magnetic field gradient (smal

  10. Size segregation in a granular bore

    Science.gov (United States)

    Edwards, A. N.; Vriend, N. M.

    2016-10-01

    We investigate the effect of particle-size segregation in an upslope propagating granular bore. A bidisperse mixture of particles, initially normally graded, flows down an inclined chute and impacts with a closed end. This impact causes the formation of a shock in flow thickness, known as a granular bore, to travel upslope, leaving behind a thick deposit. This deposit imprints the local segregated state featuring both pure and mixed regions of particles as a function of downstream position. The particle-size distribution through the depth is characterized by a thin purely small-particle layer at the base, a significant linear transition region, and a thick constant mixed-particle layer below the surface, in contrast to previously observed S-shaped steady-state concentration profiles. The experimental observations agree with recent progress that upward and downward segregation of large and small particles respectively is asymmetric. We incorporate the three-layer, experimentally observed, size-distribution profile into a depth-averaged segregation model to modify it accordingly. Numerical solutions of this model are able to match our experimental results and therefore motivate the use of a more general particle-size distribution profile.

  11. Chromosome Segregation: Organizing Overlap at the Midzone

    NARCIS (Netherlands)

    Janson, M.E.; Tran, P.T.

    2008-01-01

    Sets of overlapping microtubules support the segregation of chromosomes by linking the poles of mitotic spindles. Recent work examines the effect of putting these linkages under pressure by the activation of dicentric chromosomes and sheds new light on the structural role of several well-known spind

  12. Why Are English Secondary Schools Socially Segregated?

    Science.gov (United States)

    Coldron, John; Cripps, Caroline; Shipton, Lucy

    2010-01-01

    This paper seeks an explanation for the persistent social phenomenon of segregated schooling in England whereby children from families with broadly the same characteristics of wealth, education and social networks are more likely to be educated together and therefore separate from children from more socially distant groups. The paper outlines the…

  13. 17 CFR 31.12 - Segregation.

    Science.gov (United States)

    2010-04-01

    ... convenience be commingled with other leverage customer funds and deposited in the same account or accounts....12 Segregation. (a) Any person that accepts leverage customer funds from a leverage customer to enter into or maintain a leverage contract shall treat and deal with such leverage customer funds...

  14. Segregation analysis of urothelial cell carcinoma.

    NARCIS (Netherlands)

    Aben, K.K.H.; Baglietto, L.; Baffoe-Bonnie, A.B.; Coebergh, J.W.W.; Bailey-Wilson, J.E.; Trink, B.; Verbeek, A.L.M.; Schoenberg, M.P.; Witjes, J.A.; Kiemeney, L.A.L.M.

    2006-01-01

    A family history of urothelial cell carcinoma (UCC) confers an almost two-fold increased risk of developing UCC. It is unknown whether (part of) this aggregation of UCC has a Mendelian background. We performed complex segregation analyses on 1193 families ascertained through a proband with UCC of th

  15. Calcifying Sorting and Segregating: "Brown" at 60

    Science.gov (United States)

    Graff, Cristina Santamaria; Kozleski, Elizabeth

    2014-01-01

    The 2007 "Parents Involved in Community Schools v. Seattle School District No. 1". Supreme Court 5:4 decision suggests that the Court is divided in its interpretation of "Brown" and its intent in addressing racial segregation. Although "Brown" intended equal educational opportunities through desegregation practices,…

  16. Habitat segregation of sessile marine organisms; Kaiyo fuchaku seibutsu no sumiwake

    Energy Technology Data Exchange (ETDEWEB)

    Isoai, A. [Asahi Glass Co. Ltd., Tokyo (Japan); Kawahara, H.; Shizuri, Y.

    1996-08-01

    In order to develop the safe control agent of sessile marine organisms, the mechanism of habitat segregation of them has been investigated. Among various marine organisms, around 120 species of Porifera and Coelenterata accompanied with less the other sessile organisms were collected, to examine the adhesion prevention activity of their extracts against barnacles and Mytilus edulis. As a result, this activity was found out for 33% of Porifera and 27% of Coelenterata specimens. This means these organisms contain the adhesion prevention substances, and it is considered these chemical substances are practically used for the habitat segregation. Isolation structures of the chemical substances used for the habitat segregation were determined from these organisms. It was made clear that two acceptor genes successfully cloned from Balanus amphitrate are new G-protein coupling type acceptors having similar homology to the adrenaline and serotonin acceptors. 15 refs., 3 figs.

  17. Oxidative stress in oocytes during midprophase induces premature loss of cohesion and chromosome segregation errors.

    Science.gov (United States)

    Perkins, Adrienne T; Das, Thomas M; Panzera, Lauren C; Bickel, Sharon E

    2016-11-01

    In humans, errors in meiotic chromosome segregation that produce aneuploid gametes increase dramatically as women age, a phenomenon termed the "maternal age effect." During meiosis, cohesion between sister chromatids keeps recombinant homologs physically attached and premature loss of cohesion can lead to missegregation of homologs during meiosis I. A growing body of evidence suggests that meiotic cohesion deteriorates as oocytes age and contributes to the maternal age effect. One hallmark of aging cells is an increase in oxidative damage caused by reactive oxygen species (ROS). Therefore, increased oxidative damage in older oocytes may be one of the factors that leads to premature loss of cohesion and segregation errors. To test this hypothesis, we used an RNAi strategy to induce oxidative stress in Drosophila oocytes and measured the fidelity of chromosome segregation during meiosis. Knockdown of either the cytoplasmic or mitochondrial ROS scavenger superoxide dismutase (SOD) caused a significant increase in segregation errors, and heterozygosity for an smc1 deletion enhanced this phenotype. FISH analysis indicated that SOD knockdown moderately increased the percentage of oocytes with arm cohesion defects. Consistent with premature loss of arm cohesion and destabilization of chiasmata, the frequency at which recombinant homologs missegregate during meiosis I is significantly greater in SOD knockdown oocytes than in controls. Together these results provide an in vivo demonstration that oxidative stress during meiotic prophase induces chromosome segregation errors and support the model that accelerated loss of cohesion in aging human oocytes is caused, at least in part, by oxidative damage.

  18. Early-life sexual segregation: ontogeny of isotopic niche differentiation in the Antarctic fur seal.

    Science.gov (United States)

    Kernaléguen, L; Arnould, J P Y; Guinet, C; Cazelles, B; Richard, P; Cherel, Y

    2016-09-13

    Investigating the ontogeny of niche differentiation enables to determine at which life-stages sexual segregation arises, providing insights into the main factors driving resource partitioning. We investigated the ontogeny of foraging ecology in Antarctic fur seals (Arctocephalus gazella), a highly dimorphic species with contrasting breeding strategies between sexes. Sequential δ(13)C and δ(15)N values of whiskers provided a longitudinal proxy of the foraging niche throughout the whole life of seals, from weaning, when size dimorphism is minimal to the age of 5. Females exhibited an early-life ontogenetic shift, from a total segregation during their first year at-sea, to a similar isotopic niche as breeding females as early as age 2. In contrast, males showed a progressive change in isotopic niche throughout their development such that 5-year-old males did not share the same niche as territorial bulls. Interestingly, males and females segregated straight after weaning with males appearing to feed in more southerly habitats than females. This spatial segregation was of similar amplitude as observed in breeding adults and was maintained throughout development. Such early-life niche differentiation is an unusual pattern and indicates size dimorphism and breeding constraints do not directly drive sexual segregation contrary to what has been assumed in otariid seals.

  19. Early-life sexual segregation: ontogeny of isotopic niche differentiation in the Antarctic fur seal

    Science.gov (United States)

    Kernaléguen, L.; Arnould, J. P. Y.; Guinet, C.; Cazelles, B.; Richard, P.; Cherel, Y.

    2016-09-01

    Investigating the ontogeny of niche differentiation enables to determine at which life-stages sexual segregation arises, providing insights into the main factors driving resource partitioning. We investigated the ontogeny of foraging ecology in Antarctic fur seals (Arctocephalus gazella), a highly dimorphic species with contrasting breeding strategies between sexes. Sequential δ13C and δ15N values of whiskers provided a longitudinal proxy of the foraging niche throughout the whole life of seals, from weaning, when size dimorphism is minimal to the age of 5. Females exhibited an early-life ontogenetic shift, from a total segregation during their first year at-sea, to a similar isotopic niche as breeding females as early as age 2. In contrast, males showed a progressive change in isotopic niche throughout their development such that 5-year-old males did not share the same niche as territorial bulls. Interestingly, males and females segregated straight after weaning with males appearing to feed in more southerly habitats than females. This spatial segregation was of similar amplitude as observed in breeding adults and was maintained throughout development. Such early-life niche differentiation is an unusual pattern and indicates size dimorphism and breeding constraints do not directly drive sexual segregation contrary to what has been assumed in otariid seals.

  20. Modeling size segregation of granular materials: the roles of segregation, advection and diffusion

    CERN Document Server

    Fan, Yi; Umbanhowar, Paul B; Ottino, Julio M; Lueptow, Richard M

    2014-01-01

    Predicting segregation of granular materials composed of different-sized particles is a challenging problem. In this paper, we develop and implement a theoretical model that captures the interplay between advection, segregation, and diffusion in size bidisperse granular materials. The fluxes associated with these three driving factors depend on the underlying kinematics, whose characteristics play key roles in determining particle segregation configurations. Unlike previous models for segregation, our model uses parameters based on kinematic measures from discrete element method simulations instead of arbitrarily adjustable fitting parameters, and it achieves excellent quantitative agreement with both experimental and simulation results when applied to quasi-two-dimensional bounded heaps. The model yields two dimensionless control parameters, both of which are only functions of physically control parameters (feed rate, particle sizes, and system size) and kinematic parameters (diffusion coefficient, flowing l...

  1. Control on Housing Segregation:Housing Modes and Public Policies

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>1. Housing segregation:advocating or controlling?The phenomenon of housing segregation has become more and more obvious in Chinese cities in recent years; however, there is no agreement on whether it should

  2. Socially segregated, sympatric sperm whale clans in the Atlantic Ocean

    Science.gov (United States)

    Bøttcher, Anne; Whitehead, Hal

    2016-01-01

    Sperm whales (Physeter macrocephalus) are unusual in that there is good evidence for sympatric populations with distinct culturally determined behaviour, including potential acoustic markers of the population division. In the Pacific, socially segregated, vocal clans with distinct dialects coexist; by contrast, geographical variation in vocal repertoire in the Atlantic has been attributed to drift. We examine networks of acoustic repertoire similarity and social interactions for 11 social units in the Eastern Caribbean. We find the presence of two socially segregated, sympatric vocal clans whose dialects differ significantly both in terms of categorical coda types produced by each clan (Mantel test between clans: matrix correlation = 0.256; p ≤ 0.001) and when using classification-free similarity which ignores defined types (Mantel test between clans: matrix correlation = 0.180; p ≤ 0.001). The more common of the two clans makes a characteristic 1 + 1 + 3 coda, while the other less often sighted clan makes predominantly regular codas. Units were only observed associating with other units within their vocal clan. This study demonstrates that sympatric vocal clans do exist in the Atlantic, that they define a higher order level of social organization as they do in the Pacific, and suggests that cultural identity at the clan level is probably important in this species worldwide. PMID:27429766

  3. Segregation behavior of phosphorus in the heat-affected zone of an A533B/A182 dissimilar weld joint before and after simulated thermal aging

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Ziqing, E-mail: ziqing.zhai@rbm.qse.tohoku.ac.jp [Graduate School of Engineering, Tohoku University, 6-6-01-2 Aoba, Aramaki, Aoba-Ku, Sendai 980-8579 (Japan); Miyahara, Yuichi [Material Science Research Laboratory, Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196 (Japan); Abe, Hiroshi; Watanabe, Yutaka [Graduate School of Engineering, Tohoku University, 6-6-01-2 Aoba, Aramaki, Aoba-Ku, Sendai 980-8579 (Japan)

    2014-09-15

    Highlights: • Impacts of aging on P segregation in actual heat-affected zone were examined by 3D-APT. • Non-equilibrium segregation of P dominated in subsequent cooling after welding. • Equilibrium segregation of P prevailed in step-cooling heat treatment. • High enrichment of P at grain/packet boundaries occurred in CGHAZ and ICCGHAZ. • Level of P enrichment at precipitate/matrix interface seemed species-dependent. - Abstract: The segregation behavior of phosphorus (P) in the heat-affected zone (HAZ) of an A533B/A182 dissimilar weld joint before and after step cooling was investigated with atom probe tomography. At grain/packet boundaries, the final P segregation level consisted of non-equilibrium segregation that occurred during cooling after welding and post-weld heat treatment (PWHT) and equilibrium segregation that occurred during step cooling. In both processes, higher P coverage was observed in the coarse-grained and intercritically reheated coarse-grained HAZ than in the fine-grained HAZ and base material. The cooling after welding and PWHT seemed to have a pronounced impact on P segregation in the subsequent aging process. In addition, P segregation also occurred at the precipitate/matrix interfaces of cementite, Mo{sub 2}C and Al–Si rich precipitates. The evolution of P coverage at these two types of sites suggested increasing risks of embrittlement with an increase in aging time.

  4. 46 CFR 151.13-5 - Cargo segregation-tanks.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo segregation-tanks. 151.13-5 Section 151.13-5... CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Cargo Segregation § 151.13-5 Cargo segregation—tanks. (a... symbols used in lines 1 and 2, in order, under the tank segregation column of Table 151.05....

  5. Residential segregation of socioeconomic variables and health indices in Iran

    Directory of Open Access Journals (Sweden)

    Seyed Saeed Hashemi Nazari

    2013-01-01

    Conclusions: Correlation of segregation of determinants of socioeconomic status with segregation of health indices is an indicator of existence of hot zones of health problems across some provinces. Further studies using multilevel modeling and individual data in health outcomes at individual level and segregation measures at appropriate geographic levels are required to confirm these relations.

  6. Within-School Segregation in an Urban School District

    Science.gov (United States)

    Conger, Dylan

    2005-01-01

    This article examines ethnic segregation, defined as segregation among racial groups as well as between native-born and immigrant students, across elementary school classrooms in New York City. Specifically, the study compares patterns in within-school segregation across ethnic groups, grades, boroughs, and years. Current levels of within-school…

  7. 41 CFR 60-1.8 - Segregated facilities.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true Segregated facilities. 60...; Compliance Reports § 60-1.8 Segregated facilities. To comply with its obligations under the Order, a contractor must ensure that facilities provided for employees are provided in such a manner that segregation...

  8. "E Pluribus"... Separation: Deepening Double Segregation for More Students

    Science.gov (United States)

    Orfield, Gary; Kucsera, John; Siegel-Hawley, Genevieve

    2012-01-01

    This report shows segregation has increased dramatically across the country for Latino students, who are attending more intensely segregated and impoverished schools than they have for generations. The segregation increases have been the most dramatic in the West. The typical Latino student in the region attends a school where less than a quarter…

  9. Niche Segregation between Wild and Domestic Herbivores in Chilean Patagonia

    Science.gov (United States)

    Iranzo, Esperanza C.; Traba, Juan; Acebes, Pablo; González, Benito A.; Mata, Cristina; Estades, Cristián F.; Malo, Juan E.

    2013-01-01

    Competition arises when two co-occuring species share a limiting resource. Potential for competition is higher when species have coexisted for a short time, as it is the case for herbivores and livestock introduced in natural systems. Sheep, introduced in the late 19th century in Patagonia, bear a great resemblance in size and diet to the guanaco, the main native herbivore in Patagonia. In such circumstances, it could be expected that the two species compete and one of them could be displaced. We investigated spatial overlap and habitat selection by coexisting sheep and guanaco in winter and in summer. Additionally, we studied habitat selection of the guanaco in a control situation free from sheep, both in summer and winter. We also determined overlap between species in areas with different intensity of use (named preferred and marginal areas) in order to further detect the potential level of competition in the case of overlapping. Guanaco and sheep showed significantly different habitat preferences through all seasons, in spite of their spatial overlap at landscape scale. Additionally, the habitat used by guanaco was similar regardless of the presence or absence of livestock, which further indicates that sheep is not displacing guanaco where they coexist. These results suggest that habitat segregation between guanaco and sheep is due to a differential habitat selection and not to a competitive displacement process. Therefore, the potential for competition is considered low, contrary to what has been previously observed, although this could be a density-dependent result. PMID:23555656

  10. Toward hyper-resolution land-surface modeling: The effects of fine-scale topography and soil texture on CLM4.0 simulations over the Southwestern U.S.

    Science.gov (United States)

    Singh, R. S.; Reager, J. T.; Miller, N. L.; Famiglietti, J. S.

    2015-04-01

    Increasing computational efficiency and the need for improved accuracy are currently driving the development of "hyper-resolution" land-surface models that can be implemented at continental scales with resolutions of 1 km or finer. Here we report research incorporating fine-scale grid resolutions into the NCAR Community Land Model (CLM v4.0) for simulations at 1, 25, and 100 km resolution using 1 km soil and topographic information. Multiyear model runs were performed over the Southwestern U.S., including the entire state of California and the Colorado River basin. The results show changes in the total amount of CLM-modeled water storage, and changes in the spatial and temporal distributions of water in snow and soil reservoirs, as well as changes in surface fluxes and the energy balance. To inform future model progress and continued development needs and weaknesses, we compare simulation outputs to station and gridded observations of model fields. Although the higher grid-resolution model is not driven by high-resolution forcing, grid resolution changes alone yield significant improvement (reduction in error) between model outputs and observations, where the RMSE decreases by more than 35%, 36%, 34%, and 12% for soil moisture, terrestrial water storage anomaly, sensible heat, and snow water equivalent, respectively. As an additional exercise, we performed a 100 m resolution simulation over a spatial subdomain. Those results indicate that parameters such as drainage, runoff, and infiltration are significantly impacted when hillslope scales of ˜100 m or finer are considered, and we show the ways in which limitations of the current model physics, including no lateral flow between grid cells, may affect model simulation accuracy.

  11. Size Segregation in Rapid Flows of Inelastic Particles with Continuous Size Distributions

    Institute of Scientific and Technical Information of China (English)

    LI Rui; ZHANG Duan-Ming; LI Zhi-Hao

    2012-01-01

    Two-dimensional numerical simulations are employed to gain insight into the segregation behavior of granular mixtures with a power-law particle size distribution in the presence of a granular temperature gradient.It is found that particles of all sizes move toward regions of low granular temperature.Species segregation is also observed.Large particles demonstrate a higher affinity for the low-temperature regions and accumulate in these cool regions to a greater extent than their smaller counterparts.Furthermore,the local particle size distribution maintains the same form as the overall (including all particles) size distribution.%Two-dimensional numerical simulations are employed to gain insight into the segregation behavior of granular mixtures with a power-law particle size distribution in the presence of a granular temperature gradient. It is found that particles of all sizes move toward regions of low granular temperature. Species segregation is also observed. Large particles demonstrate a higher affinity for the low-temperature regions and accumulate in these cool regions to a greater extent than their smaller counterparts. Furthermore, the local particle size distribution maintains the same form as the overall (including all particles) size distribution.

  12. Time scale of entropic segregation of flexible polymers in confinement: Implications for chromosome segregation in filamentous bacteria

    OpenAIRE

    Arnold, Axel; Jun, Suckjoon

    2007-01-01

    We report molecular dynamics simulations of the segregation of two overlapping chains in cylindrical confinement. We find that the entropic repulsion between the chains can be sufficiently strong to cause segregation on a time scale that is short compared to the one for diffusion. This result implies that entropic driving forces are sufficiently strong to cause rapid bacterial chromosome segregation.

  13. Time scale of entropic segregation of flexible polymers in confinement: Implications for chromosome segregation in filamentous bacteria

    Science.gov (United States)

    Arnold, Axel; Jun, Suckjoon

    2007-09-01

    We report molecular dynamics simulations of the segregation of two overlapping chains in cylindrical confinement. We find that the entropic repulsion between chains can be sufficiently strong to cause segregation on a time scale that is short compared to the one for diffusion. This result implies that entropic driving forces are sufficiently strong to cause rapid bacterial chromosome segregation.

  14. From Schelling to Schools : A comparison of a model of residential segregation with a model of school segregation

    NARCIS (Netherlands)

    Stoica, Victor; Flache, Andreas

    2014-01-01

    We address theoretically whether and under what conditions Schelling's celebrated result of 'self-organized' unintended residential segregation may also apply to school segregation. We propose here a computational model of school segregation that is aligned with a corresponding Schelling-type model

  15. Phase diagram of a Schelling segregation model

    Science.gov (United States)

    Gauvin, L.; Vannimenus, J.; Nadal, J.-P.

    2009-07-01

    The collective behavior in a variant of Schelling’s segregation model is characterized with methods borrowed from statistical physics, in a context where their relevance was not conspicuous. A measure of segregation based on cluster geometry is defined and several quantities analogous to those used to describe physical lattice models at equilibrium are introduced. This physical approach allows to distinguish quantitatively several regimes and to characterize the transitions between them, leading to the building of a phase diagram. Some of the transitions evoke empirical sudden ethnic turnovers. We also establish links with ‘spin-1’ models in physics. Our approach provides generic tools to analyze the dynamics of other socio-economic systems.

  16. Sister chromatid segregation in meiosis II

    Science.gov (United States)

    Wassmann, Katja

    2013-01-01

    Meiotic divisions (meiosis I and II) are specialized cell divisions to generate haploid gametes. The first meiotic division with the separation of chromosomes is named reductional division. The second division, which takes place immediately after meiosis I without intervening S-phase, is equational, with the separation of sister chromatids, similar to mitosis. This meiotic segregation pattern requires the two-step removal of the cohesin complex holding sister chromatids together: cohesin is removed from chromosome arms that have been subjected to homologous recombination in meiosis I and from the centromere region in meiosis II. Cohesin in the centromere region is protected from removal in meiosis I, but this protection has to be removed—deprotected”—for sister chromatid segregation in meiosis II. Whereas the mechanisms of cohesin protection are quite well understood, the mechanisms of deprotection have been largely unknown until recently. In this review I summarize our current knowledge on cohesin deprotection. PMID:23574717

  17. Organization and segregation of bacterial chromosomes.

    Science.gov (United States)

    Wang, Xindan; Montero Llopis, Paula; Rudner, David Z

    2013-03-01

    The bacterial chromosome must be compacted more than 1,000-fold to fit into the compartment in which it resides. How it is condensed, organized and ultimately segregated has been a puzzle for over half a century. Recent advances in live-cell imaging and genome-scale analyses have led to new insights into these problems. We argue that the key feature of compaction is the orderly folding of DNA along adjacent segments and that this organization provides easy and efficient access for protein-DNA transactions and has a central role in driving segregation. Similar principles and common proteins are used in eukaryotes to condense and to resolve sister chromatids at metaphase.

  18. Socio-Spatial Segregations in Social Media

    Directory of Open Access Journals (Sweden)

    Murat SEIFY

    2016-12-01

    Full Text Available In conjunction with developments in communication technologies, life spaces of people also change and develop. What constitutes the most important building block of these new life spaces are digital communication resources. Digital communication resources form new spaces in social media by manipulating identities and cultures. These new spaces create socio-spatial segregations, whether consciously or unconsciously. Especially in recent years, grouping is observed intensely in social media and from time to time these groups play an important role in mass actions. In this study, closed and secret groups formed in social media were examined, with qualitative and quantitative research methods. Within this context, through in-depth interviews with group admins and survey study with group members, socio-spatial segregation in social media and grouping processes in social media were examined.

  19. Phase Segregation in Polystyrene?Polylactide Blends

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Bonnie; Hitchcock, Adam; Brash, John; Scholl, Andreas; Doran, Andrew

    2010-06-09

    Spun-cast films of polystyrene (PS) blended with polylactide (PLA) were visualized and characterized using atomic force microscopy (AFM) and synchrotron-based X-ray photoemission electron microscopy (X-PEEM). The composition of the two polymers in these systems was determined by quantitative chemical analysis of near-edge X-ray absorption signals recorded with X-PEEM. The surface morphology depends on the ratio of the two components, the total polymer concentration, and the temperature of vacuum annealing. For most of the blends examined, PS is the continuous phase with PLA existing in discrete domains or segregated to the air?polymer interface. Phase segregation was improved with further annealing. A phase inversion occurred when films of a 40:60 PS:PLA blend (0.7 wt percent loading) were annealed above the glass transition temperature (Tg) of PLA.

  20. Granular segregation driven by particle interactions.

    Science.gov (United States)

    Lozano, C; Zuriguel, I; Garcimartín, A; Mullin, T

    2015-05-01

    We report the results of an experimental study of particle-particle interactions in a horizontally shaken granular layer that undergoes a second order phase transition from a binary gas to a segregation liquid as the packing fraction C is increased. By focusing on the behavior of individual particles, the effect of C is studied on (1) the process of cluster formation, (2) cluster dynamics, and (3) cluster destruction. The outcomes indicate that the segregation is driven by two mechanisms: attraction between particles with the same properties and random motion with a characteristic length that is inversely proportional to C. All clusters investigated are found to be transient and the probability distribution functions of the separation times display a power law tail, indicating that the splitting probability decreases with time.

  1. Chromosomal organization and segregation in Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Isabelle Vallet-Gely

    2013-05-01

    Full Text Available The study of chromosomal organization and segregation in a handful of bacteria has revealed surprising variety in the mechanisms mediating such fundamental processes. In this study, we further emphasized this diversity by revealing an original organization of the Pseudomonas aeruginosa chromosome. We analyzed the localization of 20 chromosomal markers and several components of the replication machinery in this important opportunistic γ-proteobacteria pathogen. This technique allowed us to show that the 6.3 Mb unique circular chromosome of P. aeruginosa is globally oriented from the old pole of the cell to the division plane/new pole along the oriC-dif axis. The replication machinery is positioned at mid-cell, and the chromosomal loci from oriC to dif are moved sequentially to mid-cell prior to replication. The two chromosomal copies are subsequently segregated at their final subcellular destination in the two halves of the cell. We identified two regions in which markers localize at similar positions, suggesting a bias in the distribution of chromosomal regions in the cell. The first region encompasses 1.4 Mb surrounding oriC, where loci are positioned around the 0.2/0.8 relative cell length upon segregation. The second region contains at least 800 kb surrounding dif, where loci show an extensive colocalization step following replication. We also showed that disrupting the ParABS system is very detrimental in P. aeruginosa. Possible mechanisms responsible for the coordinated chromosomal segregation process and for the presence of large distinctive regions are discussed.

  2. Segregation effects in DEEP2 galaxy groups

    Science.gov (United States)

    Nascimento, R. S.; Ribeiro, A. L. B.; Lopes, P. A. A.

    2016-09-01

    We investigate segregation phenomena in galaxy groups in the range of 0.2 low(z ≤ 0.6) and high (z > 0.6) redshift groups. Assuming that the color index (U - B)0 can be used as a proxy for the galaxy type, we found that the fraction of blue (star-forming) objects is higher in the high-z sample, with blue objects being dominant at MB > -19.5 for both samples, and red objects being dominant at MB low-z sample. Also, the radial variation of the red fraction indicates that there are more red objects with R low-z sample than in the high-z sample. Our analysis indicates statistical evidence of kinematic segregation, at the 99% c.l., for the low-z sample: redder and brighter galaxies present lower velocity dispersions than bluer and fainter ones. We also find a weaker evidence for spatial segregation between red and blue objects, at the 70% c.l. The analysis of the high-z sample reveals a different result: red and blue galaxies have velocity dispersion distributions not statistically distinct, although redder objects are more concentrated than the bluer ones at the 95% c.l. From the comparison of blue/red and bright/faint fractions, and considering the approximate lookback timescale between the two samples (˜3 Gyr), our results are consistent with a scenario where bright red galaxies had time to reach energy equipartition, while faint blue/red galaxies in the outskirts infall to the inner parts of the groups, thus reducing spatial segregation from z ˜ 0.8 to z ˜ 0.4.

  3. Plasmid and chromosome segregation in prokaryotes

    DEFF Research Database (Denmark)

    Møller-Jensen, Jakob; Bugge Jensen, Rasmus; Gerdes, Kenn

    2000-01-01

    Recent major advances in the understanding of prokaryotic DNA segregation have been achieved by using fluorescence microscopy to visualize the localization of cellular components. Plasmids and bacterial chromosomes are partitioned in a highly dynamic fashion, suggesting the presence of a mitotic......-like apparatus in prokaryotes. The identification of chromosomal homologues of the well-characterized plasmid partitioning genes indicates that there could be a general mechanism of bacterial DNA partitioning. Udgivelsesdato: July 1...

  4. Effects of container geometry on granular segregation pattern

    Institute of Scientific and Technical Information of China (English)

    Hu Mao-Bin; Kong Xiang-Zhao; Wu Qing-Song; Wu Yong-Hong

    2005-01-01

    In a set of vibrating quasi-two-dimensional containers with the right-hand sidewall bent inward, three new segregation patterns have been identified experimentally including a Two-Side segregation Pattern, a Left-hand Side segregation Pattern and a pattern where big particles aggregate to the upper left part of the container. In a container with small bending degree, either the two-side segregation pattern or the left-hand side segregation pattern is stable, which is determined by the initial distribution of particles.

  5. Implementing spatial segregation measures in R.

    Directory of Open Access Journals (Sweden)

    Seong-Yun Hong

    Full Text Available Reliable and accurate estimation of residential segregation between population groups is important for understanding the extent of social cohesion and integration in our society. Although there have been considerable methodological advances in the measurement of segregation over the last several decades, the recently developed measures have not been widely used in the literature, in part due to their complex calculation. To address this problem, we have implemented several newly proposed segregation indices in R, an open source software environment for statistical computing and graphics, as a package called seg. Although there are already a few standalone applications and add-on packages that provide access to similar methods, our implementation has a number of advantages over the existing tools. First, our implementation is flexible in the sense that it provides detailed control over the calculation process with a wide range of input parameters. Most of the parameters have carefully chosen defaults, which perform acceptably in many situations, so less experienced users can also use the implemented functions without too much difficulty. Second, there is no need to export results to other software programs for further analysis. We provide coercion methods that enable the transformation of our output classes into general R classes, so the user can use thousands of standard and modern statistical techniques, which are already available in R, for the post-processing of the results. Third, our implementation does not require commercial software to operate, so it is accessible to a wider group of people.

  6. Audiovisual segregation in cochlear implant users.

    Directory of Open Access Journals (Sweden)

    Simon Landry

    Full Text Available It has traditionally been assumed that cochlear implant users de facto perform atypically in audiovisual tasks. However, a recent study that combined an auditory task with visual distractors suggests that only those cochlear implant users that are not proficient at recognizing speech sounds might show abnormal audiovisual interactions. The present study aims at reinforcing this notion by investigating the audiovisual segregation abilities of cochlear implant users in a visual task with auditory distractors. Speechreading was assessed in two groups of cochlear implant users (proficient and non-proficient at sound recognition, as well as in normal controls. A visual speech recognition task (i.e. speechreading was administered either in silence or in combination with three types of auditory distractors: i noise ii reverse speech sound and iii non-altered speech sound. Cochlear implant users proficient at speech recognition performed like normal controls in all conditions, whereas non-proficient users showed significantly different audiovisual segregation patterns in both speech conditions. These results confirm that normal-like audiovisual segregation is possible in highly skilled cochlear implant users and, consequently, that proficient and non-proficient CI users cannot be lumped into a single group. This important feature must be taken into account in further studies of audiovisual interactions in cochlear implant users.

  7. Integration and segregation in auditory scene analysis

    Science.gov (United States)

    Sussman, Elyse S.

    2005-03-01

    Assessment of the neural correlates of auditory scene analysis, using an index of sound change detection that does not require the listener to attend to the sounds [a component of event-related brain potentials called the mismatch negativity (MMN)], has previously demonstrated that segregation processes can occur without attention focused on the sounds and that within-stream contextual factors influence how sound elements are integrated and represented in auditory memory. The current study investigated the relationship between the segregation and integration processes when they were called upon to function together. The pattern of MMN results showed that the integration of sound elements within a sound stream occurred after the segregation of sounds into independent streams and, further, that the individual streams were subject to contextual effects. These results are consistent with a view of auditory processing that suggests that the auditory scene is rapidly organized into distinct streams and the integration of sequential elements to perceptual units takes place on the already formed streams. This would allow for the flexibility required to identify changing within-stream sound patterns, needed to appreciate music or comprehend speech..

  8. Segregation effects in DEEP2 galaxy groups

    CERN Document Server

    Nascimento, Raquel S; Lopes, Paulo A A

    2016-01-01

    We investigate segregation phenomena in galaxy groups in the range of $0.20.6$) redshift groups. Assuming that the color index ${(U-B)_0}$ can be used as a proxy for the galaxy type, we found that the fraction of blue (star-forming) objects is higher in the high-z sample, with blue objects being dominant at $M_{B}>-19.5$ for both samples, and red objects being dominant at $M_{B}<-19.5$ only for the low-z sample. Also, the radial variation of the red fraction indicates that there are more red objects with $Rsegregation, at the 99%c.l., for the low-z sample: redder and brighter galaxies present lower velocity dispersions than bluer and fainter ones. We also find a weaker evidence for spatial segregation between red and blue objects, at the 70%c.l. The analysis of the high-z sample reveals a different result: red and blue galaxies have velocity dispersion distributions not statistically distinc...

  9. Analysis of Minor Component Segregation in Ternary Powder Mixtures

    Science.gov (United States)

    Asachi, Maryam; Hassanpour, Ali; Ghadiri, Mojtaba; Bayly, Andrew

    2017-06-01

    In many powder handling operations, inhomogeneity in powder mixtures caused by segregation could have significant adverse impact on the quality as well as economics of the production. Segregation of a minor component of a highly active substance could have serious deleterious effects, an example is the segregation of enzyme granules in detergent powders. In this study, the effects of particle properties and bulk cohesion on the segregation tendency of minor component are analysed. The minor component is made sticky while not adversely affecting the flowability of samples. The segregation extent is evaluated using image processing of the photographic records taken from the front face of the heap after the pouring process. The optimum average sieve cut size of components for which segregation could be reduced is reported. It is also shown that the extent of segregation is significantly reduced by applying a thin layer of liquid to the surfaces of minor component, promoting an ordered mixture.

  10. Analysis of Minor Component Segregation in Ternary Powder Mixtures

    Directory of Open Access Journals (Sweden)

    Asachi Maryam

    2017-01-01

    Full Text Available In many powder handling operations, inhomogeneity in powder mixtures caused by segregation could have significant adverse impact on the quality as well as economics of the production. Segregation of a minor component of a highly active substance could have serious deleterious effects, an example is the segregation of enzyme granules in detergent powders. In this study, the effects of particle properties and bulk cohesion on the segregation tendency of minor component are analysed. The minor component is made sticky while not adversely affecting the flowability of samples. The segregation extent is evaluated using image processing of the photographic records taken from the front face of the heap after the pouring process. The optimum average sieve cut size of components for which segregation could be reduced is reported. It is also shown that the extent of segregation is significantly reduced by applying a thin layer of liquid to the surfaces of minor component, promoting an ordered mixture.

  11. Evaluating segregation in granular filters for earth dams

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, K. [Cambridge Univ., Cambridge (United Kingdom); Grabinsky, M. [Toronto Univ., ON (Canada)

    2003-07-01

    This paper presented some case studies to illustrate the relationship between seepage problems encountered with earth dams and segregation of the dams' granular filters during construction. A literature review of segregation mechanisms was presented along with a laboratory investigation. The case studies showed that the current understanding of the impact of a given degree of segregation is relatively poor. The literature reveals that although segregation mechanisms are identified and analyzed, very few are likely to be predominant during earth dam construction. Laboratory studies show that a mathematical relationship can be established between the filter's grain size distribution curve and the potential degree of segregation. Therefore, a mathematical relationship can also be established with the potential for adverse dam performance. The authors proposed a field procedure which allows for the monitoring of segregation during construction by contractors and engineers. It also helps in deciding whether any segregated zones require replacement. 5 refs., 7 figs.

  12. Mutiscale Modeling of Segregation in Granular Flows

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jin [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Modeling and simulation of segregation phenomena in granular flows are investigated. Computational models at different scales ranging from particle level (microscale) to continuum level (macroscale) are employed in order to determine the important microscale physics relevant to macroscale modeling. The capability of a multi-fluid model to capture segregation caused by density difference is demonstrated by simulating grain-chaff biomass flows in a laboratory-scale air column and in a combine harvester. The multi-fluid model treats gas and solid phases as interpenetrating continua in an Eulerian frame. This model is further improved by incorporating particle rotation using kinetic theory for rapid granular flow of slightly frictional spheres. A simplified model is implemented without changing the current kinetic theory framework by introducing an effective coefficient of restitution to account for additional energy dissipation due to frictional collisions. The accuracy of predicting segregation rate in a gas-fluidized bed is improved by the implementation. This result indicates that particle rotation is important microscopic physics to be incorporated into the hydrodynamic model. Segregation of a large particle in a dense granular bed of small particles under vertical. vibration is studied using molecular dynamics simulations. Wall friction is identified as a necessary condition for the segregation. Large-scale force networks bearing larger-than-average forces are found with the presence of wall friction. The role of force networks in assisting rising of the large particle is analyzed. Single-point force distribution and two-point spatial force correlation are computed. The results show the heterogeneity of forces and a short-range correlation. The short correlation length implies that even dense granular flows may admit local constitutive relations. A modified minimum spanning tree (MST) algorithm is developed to asymptotically recover the force statistics in the

  13. Spatial and Temporal Habitat Segregation of Mosquitoes in Urban Florida

    Science.gov (United States)

    Juliano, Steven A.

    2014-01-01

    Understanding mechanisms fostering coexistence between invasive and resident species is important in predicting ecological, economic, or health impacts of invasive species. The non-native mosquitoes Aedes aegypti and Culex quinquefasciatus have been resident in the southeastern United States for over a century. They coexist at some urban sites with the more recent invasive Aedes albopictus, which is usually superior in interspecific competition. We tested predictions of temporal and spatial habitat segregation that foster coexistence of these resident species with the superior invasive competitor. We measured spatial and temporal patterns of site occupancy and abundance for all three species among standard oviposition traps in metropolitan Tampa, Florida. Consistent with the condition-specific competition hypothesis, A. albopictus and A. aegypti abundances were greater and C. quinquefasciatus abundance was lower late (September) versus early (June) in the rainy season, and the proportional increase of A. albopictus abundance was greater than that of A. aegypti. These results are postulated to result from greater dry-season egg mortality and associated greater rainy-season competitive superiority of larvae of A. albopictus, followed by A. aegypti, and C. quinquefasciatus. Spatial partitioning among landscape variables was also evident among species, with A. albopictus more likely to oviposit across a range of open grass landscapes whereas A. aegypti were mostly restricted to cemeteries. Culex quinquefasciatus showed a shift in abundance from cemeteries early in the rainy season to developed areas characterized by built environments with large proportions of impervious surfaces late in the rainy season, where A. albopictus was not in its highest abundance. These results suggest that both temporal and spatial variation, and their interaction, may contribute to local coexistence between Aedes and Culex mosquito species in urban areas. PMID:24621592

  14. Racial segregation and maternal smoking during pregnancy: a multilevel analysis using the racial segregation interaction index.

    Science.gov (United States)

    Yang, Tse-Chuan; Shoff, Carla; Noah, Aggie J; Black, Nyesha; Sparks, Corey S

    2014-04-01

    Drawing from both the place stratification and ethnic enclave perspectives, we use multilevel modeling to investigate the relationships between women's race/ethnicity (i.e., non-Hispanic white, non-Hispanic black, Asian, and Hispanic) and maternal smoking during pregnancy, and examine if these relationships are moderated by racial segregation in the continental United States. The results show that increased interaction with whites is associated with increased probability of maternal smoking during pregnancy, and racial segregation moderates the relationships between race/ethnicity and maternal smoking. Specifically, living in a less racially segregated area is related to a lower probability of smoking during pregnancy for black women, but it could double and almost triple the probability of smoking for Asian women and Hispanic women, respectively. Our findings provide empirical evidence for both the place stratification and ethnic enclave perspectives.

  15. Exclusion and Hierarchy of Time Scales Lead to Spatial Segregation of Molecular Motors in Cellular Protrusions

    Science.gov (United States)

    Pinkoviezky, I.; Gov, N. S.

    2017-01-01

    Molecular motors that carry cargo along biopolymer filaments within cells play a crucial role in the functioning of the cell. In particular, these motors are essential for the formation and maintenance of the cellular protrusions that play key roles in motility and specific functionalities, such as the stereocilia in hair cells. Typically, there are several species of motors, carrying different cargos, that share the same track. Furthermore, it was observed that in the mature stereocilia, the different motors occupy well-segregated bands as a function of distance from the tip. We use a totally asymmetric exclusion process model with two- and three-motor species, to study the conditions that give rise to such spatial patterns. We find that the well-segregated bands appear for motors with a strong hierarchy of attachment or detachment rates. This is a striking example of pattern formation in nonequilibrium, low-dimensional systems.

  16. Analysis of the Fine-Scale Population Structure of “Candidatus Accumulibacter phosphatis” in Enhanced Biological Phosphorus Removal Sludge, Using Fluorescence In Situ Hybridization and Flow Cytometric Sorting▿

    Science.gov (United States)

    Kim, Jeong Myeong; Lee, Hyo Jung; Kim, Sun Young; Song, Jae Jun; Park, Woojun; Jeon, Che Ok

    2010-01-01

    To investigate the fine-scale diversity of the polyphosphate-accumulating organisms (PAO) “Candidatus Accumulibacter phosphatis” (henceforth referred to as “Ca. Accumulibacter”), two laboratory-scale sequencing batch reactors (SBRs) for enhanced biological phosphorus removal (EBPR) were operated with sodium acetate as the sole carbon source. During SBR operations, activated sludge always contained morphologically different “Ca. Accumulibacter” strains showing typical EBPR performances, as confirmed by the combined technique of fluorescence in situ hybridization (FISH) and microautoradiography (MAR). Fragments of “Ca. Accumulibacter” 16S rRNA genes were retrieved from the sludge. Phylogenetic analyses together with sequences from the GenBank database showed that “Ca. Accumulibacter” 16S rRNA genes of the EBPR sludge were clearly differentiated into four “Ca. Accumulibacter” clades, Acc-SG1, Acc-SG2, Acc-SG3, and Acc-SG4. The specific FISH probes Acc444, Acc184, Acc72, and Acc119 targeting these clades and some helpers and competitors were designed by using the ARB program. Microbial characterization by FISH analysis using specific FISH probes also clearly indicated the presence of different “Ca. Accumulibacter” cell morphotypes. Especially, members of Acc-SG3, targeted by probe Acc72, were coccobacillus-shaped cells with a size of approximately 2 to 3 μm, while members of Acc-SG1, Acc-SG2, and Acc-SG4, targeted by Acc444, Acc184, and Acc119, respectively, were coccus-shaped cells approximately 1 μm in size. Subsequently, cells targeted by each FISH probe were sorted by use of a flow cytometer, and their polyphosphate kinase 1 (ppk1) gene homologs were amplified by using a ppk1-specific PCR primer set for “Ca. Accumulibacter.” The phylogenetic tree based on sequences of the ppk1 gene homologs was basically congruent with that of the 16S rRNA genes, but members of Acc-SG3 with a distinct morphology comprised two different ppk1 genes

  17. The Strata-l Experiment on Microgravity Regolith Segregation

    Science.gov (United States)

    Fries, M.; Abell, P.; Brisset, J.; Britt, D.; Colwell, J.; Durda, D.; Dove, A.; Graham, L.; Hartzell, C.; John, K.; Leonard, M.; Love, S.; Sanchez, D. P.

    2016-01-01

    complexity. The materials were sorted into three size species pre-launch, and maintained during launch and return by a device called the Entrapulator. The hypothesis under test is that the particles that constitute a granular medium in a micro-gravity environment, subjected to a known vibration environemnt, will segregate in accordance to modeled predictions. Strata-1 is currently operating on ISS, with cameras capturing images of simulant motion throughout the one year mission. Vibration data is recorded and downlinked, and the simulants will be analyzed after return to Earth.

  18. Segregation of helicity in inertial wave packets

    Science.gov (United States)

    Ranjan, A.

    2017-03-01

    Inertial waves are known to exist in the Earth's rapidly rotating outer core and could be important for the dynamo generation. It is well known that a monochromatic inertial plane wave traveling parallel to the rotation axis (along positive z ) has negative helicity while the wave traveling antiparallel (negative z ) has positive helicity. Such a helicity segregation, north and south of the equator, is necessary for the α2-dynamo model based on inertial waves [Davidson, Geophys. J. Int. 198, 1832 (2014), 10.1093/gji/ggu220] to work. The core is likely to contain a myriad of inertial waves of different wave numbers and frequencies. In this study, we investigate whether this characteristic of helicity segregation also holds for an inertial wave packet comprising waves with the same sign of Cg ,z, the z component of group velocity. We first derive the polarization relations for inertial waves and subsequently derive the resultant helicity in wave packets forming as a result of superposition of two or more waves. We find that the helicity segregation does hold for an inertial wave packet unless the wave numbers of the constituent waves are widely separated. In the latter case, regions of opposite color helicity do appear, but the mean helicity retains the expected sign. An illustration of this observation is provided by (a) calculating the resultant helicity for a wave packet formed by superposition of four upward-propagating inertial waves with different wave vectors and (b) conducting the direct numerical simulation of a Gaussian eddy under rapid rotation. Last, the possible effects of other forces such as the viscous dissipation, the Lorentz force, buoyancy stratification, and nonlinearity on helicity are investigated and discussed. The helical structure of the wave packet is likely to remain unaffected by dissipation or the magnetic field, but can be modified by the presence of linearly stable stratification and nonlinearity.

  19. Computing the complexity for Schelling segregation models

    Science.gov (United States)

    Gerhold, Stefan; Glebsky, Lev; Schneider, Carsten; Weiss, Howard; Zimmermann, Burkhard

    2008-12-01

    The Schelling segregation models are "agent based" population models, where individual members of the population (agents) interact directly with other agents and move in space and time. In this note we study one-dimensional Schelling population models as finite dynamical systems. We define a natural notion of entropy which measures the complexity of the family of these dynamical systems. The entropy counts the asymptotic growth rate of the number of limit states. We find formulas and deduce precise asymptotics for the number of limit states, which enable us to explicitly compute the entropy.

  20. Isothermal Gravitational Segregation: Algorithms and Specifications

    DEFF Research Database (Denmark)

    Halldórsson, Snorri; Stenby, Erling Halfdan

    2000-01-01

    New algorithms for calculating the isothermal equilibrium state of reservoir fluids under the influence of gravity are presented. Two types of specifications are considered: the specification of pressure and composition at a reference depth; and the specification of the total overall content...... of the reservoir, along with the reservoir geometry. It is shown how both types of calculations can be performed in an efficient and robust manner using volume-based thermodynamics. The new method makes it possible to evaluate the influence of reservoir geometry and gravity segregation on the hydrocarbon reserves...

  1. Analysis of T-DNA integration and generative segregation in transgenic winter triticale (x Triticosecale Wittmack

    Directory of Open Access Journals (Sweden)

    Hensel Goetz

    2012-09-01

    Full Text Available Abstract Background While the genetic transformation of the major cereal crops has become relatively routine, to date only a few reports were published on transgenic triticale, and robust data on T-DNA integration and segregation have not been available in this species. Results Here, we present a comprehensive analysis of stable transgenic winter triticale cv. Bogo carrying the selectable marker gene HYGROMYCIN PHOSPHOTRANSFERASE (HPT and a synthetic green fluorescent protein gene (gfp. Progeny of four independent transgenic plants were comprehensively investigated with regard to the number of integrated T-DNA copies, the number of plant genomic integration loci, the integrity and functionality of individual T-DNA copies, as well as the segregation of transgenes in T1 and T2 generations, which also enabled us to identify homozygous transgenic lines. The truncation of some integrated T-DNAs at their left end along with the occurrence of independent segregation of multiple T-DNAs unintendedly resulted in a single-copy segregant that is selectable marker-free and homozygous for the gfp gene. The heritable expression of gfp driven by the maize UBI-1 promoter was demonstrated by confocal laser scanning microscopy. Conclusions The used transformation method is a valuable tool for the genetic engineering of triticale. Here we show that comprehensive molecular analyses are required for the correct interpretation of phenotypic data collected from the transgenic plants.

  2. Direct Gamete Sequencing Reveals No Evidence for Segregation Distortion in House Mouse Hybrids.

    Directory of Open Access Journals (Sweden)

    Russell Corbett-Detig

    Full Text Available Understanding the molecular basis of species formation is an important goal in evolutionary genetics, and Dobzhansky-Muller incompatibilities are thought to be a common source of postzygotic reproductive isolation between closely related lineages. However, the evolutionary forces that lead to the accumulation of such incompatibilities between diverging taxa are poorly understood. Segregation distorters are believed to be an important source of Dobzhansky-Muller incompatibilities between hybridizing species of Drosophila as well as hybridizing crop plants, but it remains unclear if these selfish genetic elements contribute to reproductive isolation in other taxa. Here, we collected viable sperm from first-generation hybrid male progeny of Mus musculus castaneus and M. m. domesticus, two subspecies of rodent in the earliest stages of speciation. We then genotyped millions of single nucleotide polymorphisms in these gamete pools and tested for a skew in the frequency of parental alleles across the genome. We show that segregation distorters are not measurable contributors to observed infertility in these hybrid males, despite sufficient statistical power to detect even weak segregation distortion with our novel method. Thus, reduced hybrid male fertility in crosses between these nascent species is attributable to other evolutionary forces.

  3. Dynamics of Escherichia coli chromosome segregation during multifork replication.

    Science.gov (United States)

    Nielsen, Henrik J; Youngren, Brenda; Hansen, Flemming G; Austin, Stuart

    2007-12-01

    Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division, the chromosomes contain multiple replication forks and must be segregated while this complex pattern of replication is still ongoing. Here, we show that replication and segregation continue in step, starting at the origin and progressing to the replication terminus. Thus, early-replicated markers on the multiple-branched chromosomes continue to separate soon after replication to form separate protonucleoids, even though they are not segregated into different daughter cells until later generations. The segregation pattern follows the pattern of chromosome replication and does not follow the cell division cycle. No extensive cohesion of sister DNA regions was seen at any growth rate. We conclude that segregation is driven by the progression of the replication forks.

  4. Dynamics of Escherichia coli Chromosome Segregation during Multifork Replication▿

    Science.gov (United States)

    Nielsen, Henrik J.; Youngren, Brenda; Hansen, Flemming G.; Austin, Stuart

    2007-01-01

    Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division, the chromosomes contain multiple replication forks and must be segregated while this complex pattern of replication is still ongoing. Here, we show that replication and segregation continue in step, starting at the origin and progressing to the replication terminus. Thus, early-replicated markers on the multiple-branched chromosomes continue to separate soon after replication to form separate protonucleoids, even though they are not segregated into different daughter cells until later generations. The segregation pattern follows the pattern of chromosome replication and does not follow the cell division cycle. No extensive cohesion of sister DNA regions was seen at any growth rate. We conclude that segregation is driven by the progression of the replication forks. PMID:17905986

  5. Segregation, choice based letting and social housing: How housing policy can affect the segregation process

    NARCIS (Netherlands)

    Van Ham, M.; Manley, D.

    2012-01-01

    In this chapter we investigate the process of ethnic minority segregation in English social housing. Successive governments have expressed a commitment to the con-tradictory aims of providing greater choice – through the introduction of choice based letting – for households accessing an increasingly

  6. Growth Conditions Regulate the Requirements for Caulobacter Chromosome Segregation

    DEFF Research Database (Denmark)

    Shebelut, Conrad W.; Jensen, Rasmus Bugge; Gitai, Zemer

    2009-01-01

    Growth environments are important metabolic and developmental regulators. Here we demonstrate a growth environment-dependent effect on Caulobacter chromosome segregation of a small-molecule inhibitor of the MreB bacterial actin cytoskeleton. Our results also implicate ParAB as important segregation...... determinants, suggesting that multiple distinct mechanisms can mediate Caulobacter chromosome segregation and that their relative contributions can be environmentally regulated....

  7. Growth conditions regulate the requirements for Caulobacter chromosome segregation.

    Science.gov (United States)

    Shebelut, Conrad W; Jensen, Rasmus B; Gitai, Zemer

    2009-02-01

    Growth environments are important metabolic and developmental regulators. Here we demonstrate a growth environment-dependent effect on Caulobacter chromosome segregation of a small-molecule inhibitor of the MreB bacterial actin cytoskeleton. Our results also implicate ParAB as important segregation determinants, suggesting that multiple distinct mechanisms can mediate Caulobacter chromosome segregation and that their relative contributions can be environmentally regulated.

  8. Highly Nonlinear Ising Model and Social Segregation

    CERN Document Server

    Sumour, M A; Shabat, M M

    2011-01-01

    The usual interaction energy of the random field Ising model in statistical physics is modified by complementing the random field by added to the energy of the usual Ising model a nonlinear term S^n were S is the sum of the neighbor spins, and n=0,1,3,5,7,9,11. Within the Schelling model of urban segregation, this modification corresponds to housing prices depending on the immediate neighborhood. Simulations at different temperatures, lattice size, magnetic field, number of neighbors and different time intervals showed that results for all n are similar, expect for n=3 in violation of the universality principle and the law of corresponding states. In order to find the critical temperatures, for large n we no longer start with all spins parallel but instead with a random configuration, in order to facilitate spin flips. However, in all cases we have a Curie temperature with phase separation or long-range segregation only below this Curie temperature, and it is approximated by a simple formula: Tc is proportion...

  9. Theta oscillations accompanying concurrent auditory stream segregation.

    Science.gov (United States)

    Tóth, Brigitta; Kocsis, Zsuzsanna; Urbán, Gábor; Winkler, István

    2016-08-01

    The ability to isolate a single sound source among concurrent sources is crucial for veridical auditory perception. The present study investigated the event-related oscillations evoked by complex tones, which could be perceived as a single sound and tonal complexes with cues promoting the perception of two concurrent sounds by inharmonicity, onset asynchrony, and/or perceived source location difference of the components tones. In separate task conditions, participants performed a visual change detection task (visual control), watched a silent movie (passive listening) or reported for each tone whether they perceived one or two concurrent sounds (active listening). In two time windows, the amplitude of theta oscillation was modulated by the presence vs. absence of the cues: 60-350ms/6-8Hz (early) and 350-450ms/4-8Hz (late). The early response appeared both in the passive and the active listening conditions; it did not closely match the task performance; and it had a fronto-central scalp distribution. The late response was only elicited in the active listening condition; it closely matched the task performance; and it had a centro-parietal scalp distribution. The neural processes reflected by these responses are probably involved in the processing of concurrent sound segregation cues, in sound categorization, and response preparation and monitoring. The current results are compatible with the notion that theta oscillations mediate some of the processes involved in concurrent sound segregation.

  10. SOCIAL POLARIZATION AND SEGREGATION IN BEIJING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The biggest change in Beijing during the last decade has been in its social structure. This transition is changing the existing situation of social "equality", and leads to polarization both in individual communities and in society as a whole. As a result, social variations and conflicting interest are growing, and some new social groups are emerging. In this paper we seek to explore a new urban phenomenon in post-1984 Beijing: social polarization and segregation. At first, we will discuss some elements explaining social polarization. The elements and the processes can be traced back to two main aspects of the economic reforms, namely the internal reforms unleashing a huge rural exodus and the open door policy. Special attention will be paid to the new lower end of the social ladder, which is made up largely by rural migrantsthat make up the so-called floating population.Finally we will explore how these social changes translate into urban segregation, with some consideration for future develop-ments.

  11. PLC based Segregation of Scrap Material

    Directory of Open Access Journals (Sweden)

    Mangesh B. Nagapure

    2017-04-01

    Full Text Available This paper describe segregation of scrap materials using automation system. With the growing population rate, the amount of waste being produced is also increasing at a very faster rate. It is also posing a very serious problem at the industrial and domestic level to manage the wastes being dumped everywhere as landfill waste. So, it is very crucial to have some system to manage waste automatically which is currently not there. Prime Minister Modi’s mission of Swaccha Bharat Abhiyan can also be successfully implemented by the proposed system. The paper proposes a novel method where the provision is given to separate out metal and nonmetal waste into respective bins by the sensing of different sensors incorporated along the conveyor belt. Pieces of glass, paper, wood and metallic materials are separated out from proposed work. Using the segregation, most of the metal and nonmetal components like paper, glass, plastic increases the economic value of the waste to its best. For every scrap separation system, a higher level of automation demands more and more accurate programming device. So, we are using programmable logic controller (PLC as main component

  12. Requirements for the evaluation of computational speech segregation systems.

    Science.gov (United States)

    May, Tobias; Dau, Torsten

    2014-12-01

    Recent studies on computational speech segregation reported improved speech intelligibility in noise when estimating and applying an ideal binary mask with supervised learning algorithms. However, an important requirement for such systems in technical applications is their robustness to acoustic conditions not considered during training. This study demonstrates that the spectro-temporal noise variations that occur during training and testing determine the achievable segregation performance. In particular, such variations strongly affect the identification of acoustical features in the system associated with perceptual attributes in speech segregation. The results could help establish a framework for a systematic evaluation of future segregation systems.

  13. Requirements for the evaluation of computational speech segregation systems

    DEFF Research Database (Denmark)

    May, Tobias; Dau, Torsten

    2014-01-01

    Recent studies on computational speech segregation reported improved speech intelligibility in noise when estimating and applying an ideal binary mask with supervised learning algorithms. However, an important requirement for such systems in technical applications is their robustness to acoustic...... conditions not considered during training. This study demonstrates that the spectro-temporal noise variations that occur during training and testing determine the achievable segregation performance. In particular, such variations strongly affect the identification of acoustical features in the system...... associated with perceptual attributes in speech segregation. The results could help establish a framework for a systematic evaluation of future segregation systems....

  14. Modelling density segregation in flowing bidisperse granular materials

    Science.gov (United States)

    Xiao, Hongyi; Umbanhowar, Paul B.; Ottino, Julio M.; Lueptow, Richard M.

    2016-07-01

    Preventing segregation in flowing granular mixtures is an ongoing challenge for industrial processes that involve the handling of bulk solids. A recent continuum-based modelling approach accurately predicts spatial concentration fields in a variety of flow geometries for mixtures varying in particle size. This approach captures the interplay between advection, diffusion and segregation using kinematic information obtained from experiments and/or discrete element method (DEM) simulations combined with an empirically determined relation for the segregation velocity. Here, we extend the model to include density-driven segregation, thereby validating the approach for the two important cases of practical interest. DEM simulations of density bidisperse flows of mono-sized particles in a quasi-two-dimensional-bounded heap were performed to determine the dependence of the density-driven segregation velocity on local shear rate and particle concentration. The model yields theoretical predictions of segregation patterns that quantitatively match the DEM simulations over a range of density ratios and flow rates. Matching experiments reproduce the segregation patterns and quantitative segregation profiles obtained in both the simulations and the model, thereby demonstrating that the modelling approach captures the essential physics of density-driven segregation in granular heap flow.

  15. Leadership of Winter Mixed-Species Flocks by Tufted Titmice (Baeolophus bicolor: Are Titmice Passive Nuclear Species?

    Directory of Open Access Journals (Sweden)

    Thomas A. Contreras

    2011-01-01

    Full Text Available The tufted titmouse (Baeolophus bicolor, TUTI is a nuclear species in winter foraging flocks whose antipredator calls are used to manage predation risk by diverse heterospecifics. We hypothesized that satellite species in mixed flocks follow TUTI (not vice versa, thereby defining the role of TUTI as a “passive” nuclear species. We followed 20 winter mixed-species flocks in North-Central Florida and assessed angular-angular correlations between overall flock, TUTI, and satellite species movement directions. We observed significant correlations between overall flock movement directions and those of TUTI, confirming our central prediction. Within flocks, however, fine-scale movement directions of satellite species were often more highly correlated with those of other satellites than with TUTI movements. We conclude that TUTI are passive nuclear species whose movements define flock paths, but within flocks, TUTI movements may have less influence on satellite movements than do other factors.

  16. QTL identification in an interspecific grapevine cross segregating for resistance to Powdery Mildew, Downy Mildew, Black Rot, and Phylloxera

    Science.gov (United States)

    Grapevine is a highly heterozygous plant with a complex genetic background. Here, we report the use of an F1 family (N = 125) from a cross of MN1264 × MN1246 made in 2010. The cross contains at least six Vitis species in its ancestry and segregates for resistance to powdery mildew (Erysiphe necator)...

  17. Leishmania amazonensis Promastigotes Present Two Distinct Modes of Nucleus and Kinetoplast Segregation during Cell Cycle

    Science.gov (United States)

    da Silva, Marcelo Santos; Monteiro, Jomar Patrício; Nunes, Vinícius Santana; Vasconcelos, Elton José; Perez, Arina Marina; Freitas-Júnior, Lúcio de Holanda; Elias, Maria Carolina; Cano, Maria Isabel Nogueira

    2013-01-01

    Here, we show the morphological events associated with organelle segregation and their timing in the cell cycle of a reference strain of Leishmania (L.) amazonensis promastigotes, the main causative agent of Tegumentary leishmaniasis in the Americas. We show evidences that during the cell cycle, L. amazonensis promastigotes present two distinct modes of nucleus and kinetoplast segregation, which occur in different temporal order in different proportions of cells. We used DAPI-staining and EdU-labeling to monitor the segregation of DNA-containing organelles and DNA replication in wild-type parasites. The emergence of a new flagellum was observed using a specific monoclonal antibody. The results show that L. amazonensis cell cycle division is peculiar, with 65% of the dividing cells duplicating the kinetoplast before the nucleus, and the remaining 35% doing the opposite or duplicating both organelles concomitantly. In both cases, the new flagellum appeared during S to G2 phase in 1N1K cells and thus before the segregation of both DNA-containing organelles; however, we could not determine the exact timing of flagellar synthesis. Most of these results were confirmed by the synchronization of parasites using hydroxyurea. Altogether, our data show that during the cell cycle of L. amazonensis promastigotes, similarly to L. donovani, the segregation of nucleus and kinetoplast do not follow a specific order, especially when compared to other trypanosomatids, reinforcing the idea that this characteristic seems to be species-specific and may represent differences in cellular biology among members of the Leishmania genus. PMID:24278433

  18. The intensity of segregation of the OH-Isoprene reaction -measurements above the amazon rain forest-

    Science.gov (United States)

    Sörgel, Matthias; Berger, Martina; Dlugi, Ralph; Harder, Hartwig; Kesselmeier, Jürgen; Mallik, Chinmay; Marno, Daniel; Tsokankunku, Anywhere; Wolff, Stefan; Yanez-Serrano, Ana-Maria; Zelger, Michael

    2017-04-01

    Incomplete mixing (segregation) causes reduced reaction rates compared to laboratory values derived for well mixed conditions. The dominant contribution to atmospheric chemistry is given by the most important oxidizing agent, the OH-radical, which is regarded as the detergent of the atmosphere as it reacts with the majority of atmospheric pollutants and therefore accelerates their removal from the atmosphere. Hence, to understand atmospheric self-cleansing, we need to quantify and understand the budgets (sources and sinks) of OH. Budgets are generally derived by measuring mixing ratios of known source molecules (either primary or recycling) and the total sink for OH of which isoprene is an important part in the pristine rain forest. The production and loss terms are calculated by using the measured mixing ratios and the laboratory derived kinetic values. If reactants are not well mixed their actual reaction rates are lower in the atmosphere than in the laboratory. Therefore, segregation might play a substantial role in quantifying and understanding the derived budgets. We measured OH-radicals, isoprene and other species (O3, NOx, HO2, H2O) with high time resolution (1-10 Hz) shortly above a rain forest canopy (41 m above ground level) at the ATTO (Amazon Tall Tower Observatory) site (02°08'38.8''S, 58°59'59.5''W). The site is characterized by high isoprene (up to 20 ppb) and low NO (50 ppt - 500 ppt). Simultaneous measurements of OH and isoprene with high time resolution (necessary to directly calculate the intensity of segregation) are sparse. To our knowledge this is now the third dataset for OH-isoprene segregation but the first from a tropical rain forest. The results will be compared to modeling results from different environments and the effect of trace gas exchange driven by coherent structures on the intensity of segregation will be evaluated as well.

  19. Micro and Macro Segregation in Alloys Solidifying with Equiaxed Morphology

    Science.gov (United States)

    Stefanescu, Doru M.; Curreri, Peter A.; Leon-Torres, Jose; Sen, Subhayu

    1996-01-01

    To understand macro segregation formation in Al-Cu alloys, experiments were run under terrestrial gravity (1g) and under low gravity during parabolic flights (10(exp -2) g). Alloys of two different compositions (2% and 5% Cu) were solidified at two different cooling rates. Systematic microscopic and SEM observations produced microstructural and segregation maps for all samples. These maps may be used as benchmark experiments for validation of microstructure evolution and segregation models. As expected, the macro segregation maps are very complex. When segregation was measured along the central axis of the sample, the highest macro segregation for samples solidified at 1g was obtained for the lowest cooling rate. This behavior is attributed to the longer time available for natural convection and shrinkage flow to affect solute redistribution. In samples solidified under low-g, the highest macro-segregation was obtained at the highest cooling rate. In general, low-gravity solidification resulted in less segregation. To explain the experimental findings, an analytical (Flemings-Nereo) and a numerical model were used. For the numerical model, the continuum formulation was employed to describe the macroscopic transports of mass, energy, and momentum, associated with the microscopic transport phenomena, for a two-phase system. The model proposed considers that liquid flow is driven by thermal and solutal buoyancy, and by solidification shrinkage. The Flemings-Nereo model explains well macro segregation in the initial stages of low-gravity segregation. The numerical model can describe the complex macro segregation pattern and the differences between low- and high-gravity solidification.

  20. Auditory stream segregation using amplitude modulated bandpass noise

    Directory of Open Access Journals (Sweden)

    Yingjiu eNie

    2015-08-01

    Full Text Available The purpose of this study was to investigate the roles of spectral overlap and amplitude modulation (AM rate for stream segregation for noise signals, as well as to test the build-up effect based on these two cues. Segregation ability was evaluated using an objective paradigm with listeners’ attention focused on stream segregation. Stimulus sequences consisted of two interleaved sets of bandpass noise bursts (A and B bursts. The A and B bursts differed in spectrum, AM-rate, or both. The amount of the difference between the two sets of noise bursts was varied. Long and short sequences were studied to investigate the build-up effect for segregation based on spectral and AM-rate differences. Results showed the following: 1. Stream segregation ability increased with greater spectral separation. 2. Larger AM-rate separations were associated with stronger segregation abilities. 3. Spectral separation was found to elicit the build-up effect for the range of spectral differences assessed in the current study. 4. AM-rate separation interacted with spectral separation suggesting an additive effect of spectral separation and AM-rate separation on segregation build-up. The findings suggest that, when normal-hearing listeners direct their attention toward segregation, they are able to segregate auditory streams based on reduced spectral contrast cues that vary by the amount of spectral overlap. Further, regardless of the spectral separation they were able to use AM-rate difference as a secondary/weaker cue. Based on the spectral differences, listeners can segregate auditory streams better as the listening duration is prolonged—i.e. sparse spectral cues elicit build-up segregation; however, AM-rate differences only appear to elicit build-up when in combination with spectral difference cues.

  1. Segregation induced fingering instabilities in granular avalanches

    Science.gov (United States)

    Woodhouse, Mark; Thornton, Anthony; Johnson, Chris; Kokelaar, Pete; Gray, Nico

    2013-04-01

    It is important to be able to predict the distance to which a hazardous natural granular flows (e.g. snow slab avalanches, debris-flows and pyroclastic flows) might travel, as this information is vital for accurate assessment of the risks posed by such events. In the high solids fraction regions of these flows the large particles commonly segregate to the surface, where they are transported to the margins to form bouldery flow fronts. In many natural flows these bouldery margins experience a much greater frictional force, leading to frontal instabilities. These instabilities create levees that channelize the flow vastly increasing the run-out distance. A similar effect can be observed in dry granular experiments, which use a combination of small round and large rough particles. When this mixture is poured down an inclined plane, particle size segregation causes the large particles to accumulate near the margins. Being rougher, the large particles experience a greater friction force and this configuration (rougher material in front of smoother) can be unstable. The instability causes the uniform flow front to break up into a series of fingers. A recent model for particle size-segregation has been coupled to existing avalanche models through a particle concentration dependent friction law. In this talk numerical solutions of this coupled system are presented and compared to both large scale experiments carried out at the USGS flume and more controlled small scale laboratory experiments. The coupled depth-averaged model captures the accumulation of large particles at the flow front. We show this large particle accumulation at the head of the flow can lead to the break-up of the initially uniform front into a series of fingers. However, we are unable to obtain a fully grid-resolved numerical solution; the width of the fingers decreases as the grid is refined. By considering the linear stability of a steady, fully-developed, bidisperse granular layer it is shown that

  2. Ethnic Segregation in Arizona Charter Schools

    Directory of Open Access Journals (Sweden)

    Casey D. Cobb

    1999-01-01

    Full Text Available Among the criticisms of charter schools is their potential to further stratify schools along ethnic and class lines. This study addressed whether Arizona charter schools are more ethnically segregated than traditional public schools. In 1996-97, Arizona had nearly one in four of all charter schools in the United States. The analysis involved a series of comparisons between the ethnic compositions of adjacent charter and public schools in Arizona's most populated region and its rural towns. This methodology differed from the approach of many evaluations of charter schools and ethnic stratification in that it incorporated the use of geographic maps to compare schools' ethnic make-ups. The ethnic compositions of 55 urban and 57 rural charter schools were inspected relative to their traditional public school neighbors.

  3. Segregation and differential settling in flocculated tailings

    Energy Technology Data Exchange (ETDEWEB)

    Farinato, R.S.; Mahmoudkhani, A.; Fenderson, T.; Watson, P. [Kemira, Atlanta, GA (United States)

    2010-07-01

    Untreated oil sands tailings have a high solids content, have poor dewaterability, and contain no aggregates. This PowerPoint presentation investigated segregation and differential settling in flocculated tailings. Tailings were treated with gypsum and various polymers. Cylinder settling, dynamic rheometry, particle size analysis, and microscopy techniques were used to characterize the composite tailings. The particles sizes of the samples were evaluated in relation to shear rate, bed depth, and treatment. The study showed that the gypsum-treated tailings had small aggregates, size stratification, a high solids content, and poor dewaterability. The polymer N-treated tailings had the lowest solids content, good dewaterability, and weak aggregates. The polymer A-treated tailings had a low solids content, very good dewaterability, and strong aggregates. The addition of a coagulant to the polymer-A treated tailings provided weaker aggregates and a higher solids content. tabs., figs.

  4. A computer model of auditory stream segregation.

    Science.gov (United States)

    Beauvois, M W; Meddis, R

    1991-08-01

    A computer model is described which simulates some aspects of auditory stream segregation. The model emphasizes the explanatory power of simple physiological principles operating at a peripheral rather than a central level. The model consists of a multi-channel bandpass-filter bank with a "noisy" output and an attentional mechanism that responds selectively to the channel with the greatest activity. A "leaky integration" principle allows channel excitation to accumulate and dissipate over time. The model produces similar results to two experimental demonstrations of streaming phenomena, which are presented in detail. These results are discussed in terms of the "emergent properties" of a system governed by simple physiological principles. As such the model is contrasted with higher-level Gestalt explanations of the same phenomena while accepting that they may constitute complementary kinds of explanation.

  5. Dynamics of chromosome segregation in Escherichia coli

    DEFF Research Database (Denmark)

    Nielsen, Henrik Jørck

    2007-01-01

    in the cell by labeling specific parts of it. Later the dynamics of chromosome segregation was included. Investigating chromosome organization by labeling of specific loci was already a widely used technique when I started on this thesis, but the data acquisition and treatment was slow and generally poorly......, and it is obvious that structured cellular actions are required to unpack it, as required for its replication, and refold the two daughter chromosomes separately without getting them entangled in the process each generation. The intention of the study was initially to find out how the chromosome is organized....... Adding the results of the thesis together with known data results in the following description of the chromosome dynamics of slowly growing E.coli cells: The chromosome of slow growing cells is organized with the origin at the cell center when it is newborn. It has one chromosomal arm on one side...

  6. Heider balance, asymmetric ties, and gender segregation

    CERN Document Server

    Krawczyk, Małgorzata J; Hernández-Ramirez, Eric; Naumis, Gerardo G; Kułakowski, Krzysztof

    2015-01-01

    To remove a cognitive dissonance in interpersonal relations, people tend to divide our acquaintances into friendly and hostile parts, both groups internally friendly and mutually hostile. This process is modeled as an evolution towards the Heider balance. A set of differential equations have been proposed and validated (Kulakowski {\\it et al}, IJMPC 16 (2005) 707) to model the Heider dynamics of this social and psychological process. Here we generalize the model by including the initial asymmetry of the interprersonal relations and the direct reciprocity effect which removes this asymmetry. Our model is applied to the data on enmity and friendship in 37 school classes and 4 groups of teachers in M\\'exico. For each class, a stable balanced partition is obtained into two groups. The gender structure of the groups reveals stronger gender segregation in younger classes, i.e. of age below 12 years, a fact consistent with other general empirical results.

  7. Heider balance, asymmetric ties, and gender segregation

    Science.gov (United States)

    Krawczyk, Małgorzata J.; del Castillo-Mussot, Marcelo; Hernández-Ramírez, Eric; Naumis, Gerardo G.; Kułakowski, Krzysztof

    2015-12-01

    To remove a cognitive dissonance in interpersonal relations, people tend to divide their acquaintances into friendly and hostile parts, both groups internally friendly and mutually hostile. This process is modeled as an evolution toward the Heider balance. A set of differential equations have been proposed and validated (Kułakowski et al., 2005) to model the Heider dynamics of this social and psychological process. Here we generalize the model by including the initial asymmetry of the interpersonal relations and the direct reciprocity effect which removes this asymmetry. Our model is applied to the data on enmity and friendship in 37 school classes and 4 groups of teachers in México. For each class, a stable balanced partition is obtained into two groups. The gender structure of the groups reveals stronger gender segregation in younger classes, i.e. of age below 12 years, a fact consistent with other general empirical results.

  8. Resource Utilization and Temporal Segregation of Scarabaeinae (Coleoptera, Scarabaeidae) Community in a Caatinga Fragment.

    Science.gov (United States)

    Medina, A M; Lopes, P P

    2014-04-01

    We characterized dung beetles food preference and diel activity and examined the way such characteristics may structure a Scarabaeinae community in a dry forest. We sampled a fragment of Arboreal Caatinga in Milagres, Bahia, Brazil, during the dry and wet seasons, using baited pitfall (bovine spleen, human feces, cow dung, and rotten banana). Species were classified by activity (nocturnal and diurnal) and food preference (coprophagous, necrophagous, saprophagous, copro-necrophagous, and generalist). In total, 1,581 individuals belonging to 16 morphospecies were sampled, with six new records for Caatinga. The dung beetles were mainly from generalist and coprophagous species; seven species presented nocturnal activity, and five were diurnal. There was higher species richness during the day and greater abundance during the night. Species composition differences were influenced by functional guilds and beetle size according to temporal segregation. These factors may be related to physiological, morphological, and behavioral differences.

  9. Protein diversity confers specificity in plasmid segregation.

    Science.gov (United States)

    Fothergill, Timothy J G; Barillà, Daniela; Hayes, Finbarr

    2005-04-01

    The ParG segregation protein (8.6 kDa) of multidrug resistance plasmid TP228 is a homodimeric DNA-binding factor. The ParG dimer consists of intertwined C-terminal domains that adopt a ribbon-helix-helix architecture and a pair of flexible, unstructured N-terminal tails. A variety of plasmids possess partition loci with similar organizations to that of TP228, but instead of ParG homologs, these plasmids specify a diversity of unrelated, but similarly sized, partition proteins. These include the proteobacterial pTAR, pVT745, and pB171 plasmids. The ParG analogs of these plasmids were characterized in parallel with the ParG homolog encoded by the pseudomonal plasmid pVS1. Like ParG, the four proteins are dimeric. No heterodimerization was detectable in vivo among the proteins nor with the prototypical ParG protein, suggesting that monomer-monomer interactions are specific among the five proteins. Nevertheless, as with ParG, the ParG analogs all possess significant amounts of unordered amino acid residues, potentially highlighting a common structural link among the proteins. Furthermore, the ParG analogs bind specifically to the DNA regions located upstream of their homologous parF-like genes. These nucleoprotein interactions are largely restricted to cognate protein-DNA pairs. The results reveal that the partition complexes of these and related plasmids have recruited disparate DNA-binding factors that provide a layer of specificity to the macromolecular interactions that mediate plasmid segregation.

  10. Bombardment-induced segregation and redistribution

    Energy Technology Data Exchange (ETDEWEB)

    Lam, N.Q.; Wiedersich, H.

    1986-04-01

    During ion bombardment, a number of processes can alter the compositional distribution and microstructure in near-surface regions of alloys. The relative importance of each process depends principally on the target composition, temperature, and ion characteristics. In addition to displacement mixing leading to a randomization of atomic locations, and preferential loss of alloying elements by sputtering, which are dominant at relatively low temperatures, several thermally-activated processes, including radiation-enhanced diffusion, radiation-induced segregation and Gibbsian adsorption, also play important roles. At elevated temperatures, nonequilibrium point defects induced by ion impacts become mobile and tend to anneal out by recombination and diffusion to extended sinks, such as dislocations, grain boundaries and free surfaces. The high defect concentrations, far exceeding the thermodynamic equilbrium values, can enhance diffusion-controlled processes, while persistent defect fluxes, originating from the spatial non-uniformity in defect production and annihilation, give rise to local redistribution of alloy constituents because of radiation-induced segregation. Moreover, when the alloy is maintained at high temperature, Gibbsian adsorption, driven by the reduction in free energy of the system, occurs even without irradiation; it involves a compositional perturbation in a few atom layers near the alloy surface. The combination of these processes leads to the complex development of a compositionally-modified layer in the subsurface region. In the present paper, selected examples of these different phenomena and their synergistic effects on the evolution of the near-surface compositions of alloys during sputtering and ion implantation at elevated temperatures are discussed. 74 refs., 7 figs., 1 tab.

  11. Standardized Testing and School Segregation: Like Tinder for Fire?

    Science.gov (United States)

    Knoester, Matthew; Au, Wayne

    2017-01-01

    Recent research suggests that high-stakes standardized testing has played a negative role in the segregation of children by race and class in schools. In this article we review research on the overall effects of segregation, the positive and negative aspects of how desegregation plans were carried out following the 1954 Supreme Court decision…

  12. Educational Justice and Socio-Economic Segregation in Schools

    Science.gov (United States)

    Brighouse, Harry

    2007-01-01

    Sociologists exploring educational injustice often focus on socio-economic segregation as a central measure of injustice. The comprehensive ideal, furthermore, has the idea of socio-economic integration built into it. The current paper argues that socio-economic segregation is valuable only insofar as it serves other, more fundamental values. This…

  13. Using the minimum spanning tree to trace mass segregation

    CERN Document Server

    Allison, Richard J; Parker, Richard J; Zwart, Simon F Portegies; de Grijs, Richard; Kouwenhoven, M B N

    2009-01-01

    We present a new method to detect and quantify mass segregation in star clusters. It compares the minimum spanning tree (MST) of massive stars with that of random stars. If mass segregation is present, the MST length of the most massive stars will be shorter than that of random stars. This difference can be quantified (with an associated significance) to measure the degree of mass segregation. We test the method on simulated clusters in both 2D and 3D and show that the method works as expected. We apply the method to the Orion Nebula Cluster (ONC) and show that the method is able to detect the mass segregation in the Trapezium with a `mass segregation ratio' \\Lambda_{MSR}=8.0 \\pm 3.5 (where \\Lambda_{MSR}=1 is no mass segregation) down to 16 \\Msun, and also that the ONC is mass segregated at a lower level (~2.0 \\pm 0.5) down to 5 \\Msun. Below 5 \\Msun we find no evidence for any further mass segregation in the ONC.

  14. Effects of Network Segregation in Intergroup Conflict : An Experimental Analysis

    NARCIS (Netherlands)

    Takács, Károly

    2006-01-01

    Dense in-group and scarce out-group relations (network segregation) often support the emergence of conflicts between groups. A key underlying mechanism is social control that helps to overcome the collective action problem within groups, but contributes to harmful conflicts among them in segregated

  15. Segregation and Rationality in Black Status Aspiration Processes.

    Science.gov (United States)

    Hoelter, Jon W.

    1982-01-01

    Tests the hypothesis that school racial segregation affects the ability of Black students to set reasonable occupational goals. Questionnaire data collected from male high school seniors suggest that Whites develop the most rational occupational goals, and segregated Blacks the least. Desegregated education leads to increasingly rational…

  16. Sulfur segregation in titanium and selected titanium alloys

    Science.gov (United States)

    Outlaw, R. A.; Lee, W. S.; Hoekje, S. J.; Sankaran, S. N.

    1994-10-01

    The segregation of S in electrotransport-purified polycrystalline α-Ti and in several polycrystalline Ti alloys has been studied by Auger electron spectroscopy and ion scattering spectroscopy in the temperature range extending from 20 to 1000°C. The chemisorbed oxygen and carbon on Ti were observed to disappear at T ≈ 400°C after which the S signal increased to levels approaching 0.5 monolayer. At lower temperatures the presence of the surface oxygen and carbon appeared to inhibit the segregation, presumably because there were no available surfaces sites for the S emerging from the bulk. The activation energy for the S segregation in pure polycrystalline Ti was determined to be 16.7 kcal/mol, which, when compared to S segregation from single-crystal Ti, is quite small and suggest grain boundary or defect diffusion segregation kinetics. In the Ti-aluminide alloys, the presence of Al appeared to enhance the retention of surface oxygen which, in turn, substantially reduced the S segregation. The γ alloy, with its high Al content, exhibited the greatest retention of surface oxygen and the smallest quantity of S segregation ( T ≈ 1000°C). On the other hand, the β-21S alloy exhibited a greater segregation rate for the S than did α-Ti.

  17. Coleman Revisited: School Segregation, Peers, and Frog Ponds

    Science.gov (United States)

    Goldsmith, Pat Rubio

    2011-01-01

    Students from minority segregated schools tend to achieve and attain less than similar students from White segregated schools. This study examines whether peer effects can explain this relationship using normative models and frog-pond models. Normative models (where peers become alike) suggest that minority schoolmates are a liability. Frog-pond…

  18. 17 CFR 1.24 - Segregated funds; exclusions therefrom.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Segregated funds; exclusions therefrom. 1.24 Section 1.24 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION GENERAL REGULATIONS UNDER THE COMMODITY EXCHANGE ACT Customers' Money, Securities, and Property § 1.24 Segregated...

  19. 46 CFR 111.60-9 - Segregation of vital circuits.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Segregation of vital circuits. 111.60-9 Section 111.60-9...-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-9 Segregation of vital circuits. (a) General. A branch circuit that supplies equipment vital to the propulsion, control, or safety of the vessel must...

  20. "Brown" at 62: School Segregation by Race, Poverty and State

    Science.gov (United States)

    Orfield, Gary; Ee, Jongyeon; Frankenberg, Erica; Siegel-Hawley, Genevieve

    2016-01-01

    As the anniversary of "Brown v. Board of Education" decision arrives again without any major initiatives to mitigate spreading and deepening segregation in the nation's schools, the Civil Rights Project adds to a growing national discussion with a research brief drawn from a much broader study of school segregation to be published in…

  1. Figure-ground segregation in a recurrent network architecture

    NARCIS (Netherlands)

    Lamme, V.A.F.; Roelfsema, P.R.; Spekreijse, H.; Bosch, H.

    2002-01-01

    Proposes a model of how the visual brain segregate textured scenes into figures and background. During texture segregation, locations where the properties of texture elements change abruptly are assigned to boundaries, whereas image regions that are relatively homogeneous are grouped together bounda

  2. Compositional Segregation in Unidirectionally Solidified Solid Solution Crystals

    Science.gov (United States)

    Wang, J. C.

    1983-01-01

    A computer program was developed to model compositional segregation in unidrectionally solidified solid-solution-semiconducting crystals. The program takes into account the variations of the interface segregation constant and solidification rate with composition. Calculations are performed for the HgCdTe solid solution system that is compared with experimental data.

  3. Mass Segregation of Embedded Clusters in the Milky Way

    CERN Document Server

    Er, Xinyue; Fu, Yanning

    2012-01-01

    Embedded clusters are ideal laboratories to understand the early phase of the dynamical evolution of clusters as well as the massive star formation. An interesting observational phenomenon is that some of the embedded clusters show mass segregation, i.e., the most massive stars are preferentially found near the cluster center. In this paper, we develop a new approach to describe mass segregation. Using this approach and the Two Micron All Sky Survey Point Source Catalog (2MASS PSC), we analyze eighteen embedded clusters in the Galaxy. We find that eleven of them are mass-segregated and that the others are non-mass-segregated. No inversely mass-segregated cluster is found.

  4. Experimental determination of the segregation process using computer tomography

    Directory of Open Access Journals (Sweden)

    Konstantin Beckmann

    2016-07-01

    Full Text Available Modelling methods such as DEM and CFD are increasingly used for developing high efficient combine cleaning systems. For this purpose it is necessary to verify the complex segregation and separation processes in the combine cleaning system. One way is to determine the segregation and separation function using 3D computer tomography (CT. This method makes it possible to visualize and analyse the movement behaviour of the components of the mixture during the segregation and separation process as well as the derivation of descriptive process parameters. A mechanically excited miniature test rig was designed and built at the company CLAAS Selbstfahrende Erntemaschinen GmbH to achieve this aim. The investigations were carried out at the Fraunhofer Institute for Integrated Circuits IIS. Through the evaluation of the recorded images the segregation process is described visually. A more detailed analysis enabled the development of segregation and separation function based on the different densities of grain and material other than grain.

  5. Experimental determination of the segregation process using computer tomography

    Directory of Open Access Journals (Sweden)

    Konstantin Beckmann

    2016-08-01

    Full Text Available Modelling methods such as DEM and CFD are increasingly used for developing high efficient combine cleaning systems. For this purpose it is necessary to verify the complex segregation and separation processes in the combine cleaning system. One way is to determine the segregation and separation function using 3D computer tomography (CT. This method makes it possible to visualize and analyse the movement behaviour of the components of the mixture during the segregation and separation process as well as the derivation of descriptive process parameters. A mechanically excited miniature test rig was designed and built at the company CLAAS Selbstfahrende Erntemaschinen GmbH to achieve this aim. The investigations were carried out at the Fraunhofer Institute for Integrated Circuits IIS. Through the evaluation of the recorded images the segregation process is described visually. A more detailed analysis enabled the development of segregation and separation function based on the different densities of grain and material other than grain.

  6. Asphalt Mixture Segregation Detection: Digital Image Processing Approach

    Directory of Open Access Journals (Sweden)

    Mohamadtaqi Baqersad

    2017-01-01

    Full Text Available Segregation determination in the asphalt pavement is an issue causing many disputes between agencies and contractors. The visual inspection method has commonly been used to determine pavement texture and in-place core density test used for verification. Furthermore, laser-based devices, such as the Florida Texture Meter (FTM and the Circular Track Meter (CTM, have recently been developed to evaluate the asphalt mixture texture. In this study, an innovative digital image processing approach is used to determine pavement segregation. In this procedure, the standard deviation of the grayscale image frequency histogram is used to determine segregated regions. Linear Discriminate Analysis (LDA is then implemented on the obtained standard deviations from image processing to classify pavements into the segregated and nonsegregated areas. The visual inspection method is utilized to verify this method. The results have demonstrated that this new method is a robust tool to determine segregated areas in newly paved FC9.5 pavement types.

  7. Sexual Niche Segregation and Gender-Specific Individual Specialisation in a Highly Dimorphic Marine Mammal.

    Directory of Open Access Journals (Sweden)

    Laëtitia Kernaléguen

    Full Text Available While sexual segregation is expected in highly dimorphic species, the local environment is a major factor driving the degree of resource partitioning within a population. Sexual and individual niche segregation was investigated in the Australian fur seal (Arctocephalus pusillus doriferus, which is a benthic foraging species restricted to the shallow continental shelf region of south-eastern Australia. Tracking data and the isotopic values of plasma, red blood cells and whiskers were combined to document spatial and dietary niche segregation throughout the year. Tracking data indicated that, in winter, males and females overlapped in their foraging habitat. All individuals stayed within central Bass Strait, relatively close (< 220 km to the breeding colony. Accordingly, both genders exhibited similar plasma and red cell δ13C values. However, males exhibited greater δ13C intra-individual variation along the length of their whisker than females. This suggests that males exploited a greater diversity of foraging habitats throughout the year than their female counterparts, which are restricted in their foraging grounds by the need to regularly return to the breeding colony to suckle their pup. The degree of dietary sexual segregation was also surprisingly low, both sexes exhibiting a great overlap in their δ15N values. Yet, males displayed higher δ15N values than females, suggesting they fed upon a higher proportion of higher trophic level prey. Given that males and females exploit different resources (mainly foraging habitats, the degree of individual specialisation might differ between the sexes. Higher degrees of individual specialisation would be expected in males which exploit a greater range of resources. However, comparable levels of inter-individual variation in δ15N whisker values were found in the sampled males and females, and, surprisingly, all males exhibited similar seasonal and inter-annual variation in their δ13C whisker values

  8. Sexual Niche Segregation and Gender-Specific Individual Specialisation in a Highly Dimorphic Marine Mammal

    Science.gov (United States)

    Kernaléguen, Laëtitia; Cherel, Yves; Knox, Travis C.; Baylis, Alastair M. M.; Arnould, John P. Y.

    2015-01-01

    While sexual segregation is expected in highly dimorphic species, the local environment is a major factor driving the degree of resource partitioning within a population. Sexual and individual niche segregation was investigated in the Australian fur seal (Arctocephalus pusillus doriferus), which is a benthic foraging species restricted to the shallow continental shelf region of south-eastern Australia. Tracking data and the isotopic values of plasma, red blood cells and whiskers were combined to document spatial and dietary niche segregation throughout the year. Tracking data indicated that, in winter, males and females overlapped in their foraging habitat. All individuals stayed within central Bass Strait, relatively close (< 220 km) to the breeding colony. Accordingly, both genders exhibited similar plasma and red cell δ13C values. However, males exhibited greater δ13C intra-individual variation along the length of their whisker than females. This suggests that males exploited a greater diversity of foraging habitats throughout the year than their female counterparts, which are restricted in their foraging grounds by the need to regularly return to the breeding colony to suckle their pup. The degree of dietary sexual segregation was also surprisingly low, both sexes exhibiting a great overlap in their δ15N values. Yet, males displayed higher δ15N values than females, suggesting they fed upon a higher proportion of higher trophic level prey. Given that males and females exploit different resources (mainly foraging habitats), the degree of individual specialisation might differ between the sexes. Higher degrees of individual specialisation would be expected in males which exploit a greater range of resources. However, comparable levels of inter-individual variation in δ15N whisker values were found in the sampled males and females, and, surprisingly, all males exhibited similar seasonal and inter-annual variation in their δ13C whisker values, suggesting they

  9. Detection of Rsp and modifier variation in the meiotic drive system Segregation distorter (SD) of Drosophila melanogaster.

    Science.gov (United States)

    Lyttle, T W; Brittnacher, J G; Ganetzky, B

    1986-09-01

    Identification of allelic variability at the two major loci (Sd and Rsp) that interact to cause sperm dysfunction in Segregation distorter (SD) males of D. melanogaster has been hampered by the difficulty in separating the elements recombinationally. In addition, small differences in the strength of Sd alleles or sensitivities of Rsp alleles to Sd are difficult to measure against background genetic or environmental variation. Viability effects of the markers used to score progeny classes may also introduce a bias. Removal of Sd and E(SD) from their second chromosome location to create a Dp(2;Y)Sd E(SD) chromosome eliminates these problems, since any combination of Rsp alleles can be easily tested without resorting to recombinational techniques. Further, since these pairs of Rsp alleles are compared in their response to Dp Sd E(SD) in the same individual males, background variation and viability effects can be easily removed to allow fine-scale resolution of Rsp differences. Tests of all possible pairwise combination of six laboratory chromosomes in this way revealed at least three and possibly four different Rsp allelic classes. In addition, the hierarchical nature of the tests further allowed for determination of the presence of linked suppressors or enhancers of Sd activity. A sample of 11 second chromosomes selected from a group recently isolated from a natural population was also unambiguously ordered as to Rsp allelic status using this approach. The resultant pattern was similar to that obtained for the laboratory chromosomes, except for the not unexpected observation that the natural population apparently harbored more drive suppressors. The pattern of results obtained from these pairwise combinations of Rsp alleles supports the notion that there are no dominance interactions within the group, but that each responds more or less independently to Sd in giving sperm dysfunction.

  10. Bulk segregant analysis using single nucleotide polymorphism microarrays.

    Directory of Open Access Journals (Sweden)

    Anthony Becker

    Full Text Available Bulk segregant analysis (BSA using microarrays, and extreme array mapping (XAM have recently been used to rapidly identify genomic regions associated with phenotypes in multiple species. These experiments, however, require the identification of single feature polymorphisms (SFP between the cross parents for each new combination of genotypes, which raises the cost of experiments. The availability of the genomic polymorphism data in Arabidopsis thaliana, coupled with the efficient designs of Single Nucleotide Polymorphism (SNP genotyping arrays removes the requirement for SFP detection and lowers the per array cost, thereby lowering the overall cost per experiment. To demonstrate that these approaches would be functional on SNP arrays and determine confidence intervals, we analyzed hybridizations of natural accessions to the Arabidopsis ATSNPTILE array and simulated BSA or XAM given a variety of gene models, populations, and bulk selection parameters. Our results show a striking degree of correlation between the genotyping output of both methods, which suggests that the benefit of SFP genotyping in context of BSA can be had with the cheaper, more efficient SNP arrays. As a final proof of concept, we hybridized the DNA from bulks of an F2 mapping population of a Sulfur and Selenium ionomics mutant to both the Arabidopsis ATTILE1R and ATSNPTILE arrays, which produced almost identical results. We have produced R scripts that prompt the user for the required parameters and perform the BSA analysis using the ATSNPTILE1 array and have provided them as supplemental data files.

  11. More reliable inference for the dissimilarity index of segregation.

    Science.gov (United States)

    Allen, Rebecca; Burgess, Simon; Davidson, Russell; Windmeijer, Frank

    2015-02-01

    The most widely used measure of segregation is the so-called dissimilarity index. It is now well understood that this measure also reflects randomness in the allocation of individuals to units (i.e. it measures deviations from evenness, not deviations from randomness). This leads to potentially large values of the segregation index when unit sizes and/or minority proportions are small, even if there is no underlying systematic segregation. Our response to this is to produce adjustments to the index, based on an underlying statistical model. We specify the assignment problem in a very general way, with differences in conditional assignment probabilities underlying the resulting segregation. From this, we derive a likelihood ratio test for the presence of any systematic segregation, and bias adjustments to the dissimilarity index. We further develop the asymptotic distribution theory for testing hypotheses concerning the magnitude of the segregation index and show that the use of bootstrap methods can improve the size and power properties of test procedures considerably. We illustrate these methods by comparing dissimilarity indices across school districts in England to measure social segregation.

  12. Segregation and layering in the flow of wet granular matter

    Science.gov (United States)

    Samadani, Azadeh; Kudrolli, Arshad

    2000-11-01

    We report the effect of interstitial fluid on the extent of segregation by imaging the pile that results after bidisperse color-coded glass particles are poured into a silo. Segregation is sharply reduced and the angle of repose increases when a small volume fraction of fluid is added. The phase diagram of segregation as a function of volume fraction of the fluid and the size ratio of the particles is obtained. We also find that viscous forces in addition to capillary forces have an important effect on the extent of segregation and the angle of repose. We show that the sharp initial change and the subsequent saturation in the extent of segregation and angle of repose occurs over similar volume fraction of the fluid. Preferential clumping of small particles causes layering to occur when the size of the clumps of small particles exceeds the size of smoother large particles. We calculate the azimuthal correlation function of particle density inside the pile to characterize the layering. Finally the progress of segregation in the limit where particles are completely immersed in a fluid was measured. In this case liquid bridges and capillary forces are absent but viscous forces are present. We find that a transition back to segregation can occur when the particles are completely immersed in a fluid at low viscosities.

  13. Ionic Segregation on Grain Boundaries in Thermally Grown Alumina Scales

    Energy Technology Data Exchange (ETDEWEB)

    Pint, Bruce A [ORNL; Unocic, Kinga A [ORNL

    2012-01-01

    This study first examined segregation behaviour in the alumina scale formed after 100 h at 1100 C on bare and MCrAlYHfSi-coated single-crystal superalloys with {approx}10 ppma La and Y. For the bare superalloy, Hf and Ti were detected on the grain boundaries of the inner columnar alumina layer. Increasing the oxidation temperature to 1200 C for 2 h did not change the segregation behavior. With the bond coating, both Y and Hf were segregated to the grain boundaries as expected. However, there was evidence of Ti-rich oxide particles near the gas interface suggesting that Ti diffused from the superalloy through the coating. To further understand these segregation observations with multiple dopants, other alumina-forming systems were examined. Alumina scale grain boundary co-segregation of Ti with Y is common for FeCrAl alloys. Co-segregation of Hf and Ti was observed in the scale formed on co-doped NiAl. No La segregation was detected in the scale formed on NiCrAl with only a 19 ppma La addition, however, the scale was adherent.

  14. Escherichia coli Chromosomal Loci Segregate from Midcell with Universal Dynamics.

    Science.gov (United States)

    Cass, Julie A; Kuwada, Nathan J; Traxler, Beth; Wiggins, Paul A

    2016-06-21

    The structure of the Escherichia coli chromosome is inherently dynamic over the duration of the cell cycle. Genetic loci undergo both stochastic motion around their initial positions and directed motion to opposite poles of the rod-shaped cell during segregation. We developed a quantitative method to characterize cell-cycle dynamics of the E. coli chromosome to probe the chromosomal steady-state mobility and segregation process. By tracking fluorescently labeled chromosomal loci in thousands of cells throughout the entire cell cycle, our method allows for the statistical analysis of locus position and motion, the step-size distribution for movement during segregation, and the locus drift velocity. The robust statistics of our detailed analysis of the wild-type E. coli nucleoid allow us to observe loci moving toward midcell before segregation occurs, consistent with a replication factory model. Then, as segregation initiates, we perform a detailed characterization of the average segregation velocity of loci. Contrary to origin-centric models of segregation, which predict distinct dynamics for oriC-proximal versus oriC-distal loci, we find that the dynamics of loci were universal and independent of genetic position.

  15. Taylor revisited: Gender segregation and division of labour in the ICT - sector (information and communication technology)

    DEFF Research Database (Denmark)

    Nygaard, Else

    2001-01-01

    Information and communication technology, division of labour, gender segregation, working conditions......Information and communication technology, division of labour, gender segregation, working conditions...

  16. Hybridization, transgressive segregation and evolution of new genetic systems in Drosophila

    Indian Academy of Sciences (India)

    H. A. Ranganath; S. Aruna

    2003-12-01

    Introgressive hybridization facilitates incorporation of genes from one species into the gene pool of another. Studies on long-term effects of introgressive hybridization in animal systems are sparse. Drosophila nasuta ($2n = 8$) and D. albomicans ($2n = 6$)—a pair of allopatric, morphologically almost identical, cross-fertile members of the nasuta subgroup of the immigrans species group—constitute an excellent system to analyse the impact of hybridization followed by transgressive segregation of parental characters in the hybrid progeny. Hybrid populations of D. nasuta and D. albomicans maintained for over 500 generations in the laboratory constitute new recombinant hybrid genomes, here termed cytoraces. The impact of hybridization, followed by introgression and transgressive segregation, on chromosomal constitution and karyotypes, some fitness parameters, isozymes, components of mating behaviour and mating preference reveals a complex pattern of interracial divergence among parental species and cytoraces. This assemblage of characters in different combinations in a laboratory hybrid zone allows us to study the emergence of new genetic systems. Here, we summarize results from our ongoing studies comparing these hybrid cytoraces with the parental species, and discuss the implications of these findings for our understanding of the evolution of new genetic systems.

  17. Urban Segregation with Cheap and Expensive Residences

    Science.gov (United States)

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

    In this paper we study urban segregation of two different communities A and B, rich and poor, distributed randomly on finite samples, to check cheap and expensive residences. For this purpose we avoid the complications of the Schelling model which are not necessary and instead we use the Ising model on 500 × 500 square lattices, which gives similar results, with random magnetic field at lower and higher temperatures (kBT/J = 2.0, 99.0) in finite times equal to 40, 400, 4000 and 40 000. This random-field Ising magnet is a suitable model, where each site of the square lattice carries a magnetic field ±h which is randomly up (expensive) or down (cheap). The resulting addition to the energy prefers up-spins on the expensive and down-spins on the cheap sites. Our simulations were carried out using a 50-line FORTRAN program. We present at a lower temperature (2.0) a time series of pictures, separating growing from non-growing domains. A small random field (h = ±0.1) allows for large domains, while a large random field (h = ±0.9) allows only small clusters. At higher temperature (99.0) we could not obtain growing domains.

  18. Homolog pairing and segregation in Drosophila meiosis.

    Science.gov (United States)

    McKee, B D

    2009-01-01

    Pairing of homologous chromosomes is fundamental to their reliable segregation during meiosis I and thus underlies sexual reproduction. In most eukaryotes homolog pairing is confined to prophase of meiosis I and is accompanied by frequent exchanges, known as crossovers, between homologous chromatids. Crossovers give rise to chiasmata, stable interhomolog connectors that are required for bipolar orientation (orientation to opposite poles) of homologs during meiosis I. Drosophila is unique among model eukaryotes in exhibiting regular homolog pairing in mitotic as well as meiotic cells. I review the results of recent molecular studies of pairing in both mitosis and meiosis in Drosophila. These studies show that homolog pairing is continuous between pre-meiotic mitosis and meiosis but that pairing frequencies and patterns are altered during the mitotic-meiotic transition. They also show that, with the exception of X-Y pairing in male meiosis, which is mediated specifically by the 240-bp rDNA spacer repeats, chromosome pairing is not restricted to specific sites in either mitosis or meiosis. Instead, virtually all chromosome regions, both heterochromatic and euchromatic, exhibit autonomous pairing capacity. Mutations that reduce the frequencies of both mitotic and meiotic pairing have been recently described, but no mutations that abolish pairing completely have been discovered, and the genetic control of pairing in Drosophila remains to be elucidated.

  19. Mass Segregation in the Galactic Centre

    CERN Document Server

    Hopman, Clovis

    2010-01-01

    Two-body energy exchange between stars orbiting massive black holes (MBHs) leads to the formation of a power-law density distribution n(r)~r^(-a) that diverges towards the MBH. For a single mass population, a=7/4 and the flow of stars is much less than N(segregation with the use of Fokker-Planck calculations, and show that steady state is reached in 0.2-0.3 t_r. Since the relaxation time in the Galactic centre (GC) is t_r ~2-3 * 10^(10) yr, a cusp should form in less than a Hubble time. The absence of a visible cusp of old stars in the GC poses a challenge to these models, ...

  20. Itokawa: a case for ballistic segregation

    Science.gov (United States)

    Shinbrot, Troy; Sabawula, Tapan; Siu, Theo; Vivar Lazo, Miguel; Chakraborty, Pinaki

    Recent photographs of the asteroid Itokawa have revealed strong separation between regions populated almost entirely by small pebbles and other regions consisting only of larger boulders. This size separation has been attributed to the Brazil Nut Effect (BNE), however we point out here that the BNE depends on conditions such as isotropic gravity, parallel sidewalls and periodic vertical shaking that are wholly absent on asteroids. On the other hand, surface areas of boulders and pebbles appear to be comparable on Itokawa, and in this situation it follows that the asteroid must have suffered many orders of magnitude more collisions with pebbles than with boulders. We observe that a pebble will tend to bounce off of a boulder but will sink into a sea of similar pebbles, and so we predict that seas of pebbles must grow on such asteroids. We carry out experiments and simulations to evaluate this and related predictions, and we demonstrate that this new mechanism of segregation based on simple counting of grains can produce the strong separation of sizes reported. Support provided by NSF Grant 1404792.

  1. Charge segregation in weakly ionized microgels

    Science.gov (United States)

    Hyatt, John S.; Douglas, Alison M.; Stanley, Chris; Do, Changwoo; Barker, Thomas H.; Fernández-Nieves, Alberto

    2017-01-01

    We investigate microgels synthesized from N -isopropylacrylamide (NIPAM) copolymerized with a large mol% of acrylic acid, finding that when the acid groups are partially ionized at high temperatures, competition between ion-induced swelling and hydrophobic deswelling of poly(NIPAM) chains results in microphase separation. In cross-linked microgels, this manifests as a dramatic decrease in the ratio between the radius of gyration and the hydrodynamic radius to ˜0.2 , indicating that almost all the mass of the microgel is concentrated near the particle center. We also observe a concurrent decrease of the polymer network length scale via small-angle neutron scattering, confirming the presence of a dense, deswollen core surrounded by a diffuse, charged periphery. We compare these results to those obtained for a system of charged ultralow-cross-linked microgels; the form factor shows a distinct peak at high q when the temperature exceeds a threshold value. We successfully fit the form factor to theory developed to describe scattering from weakly charged gels in poor solvents, and we tie this behavior to charge segregation in the case of the cross-linked microgels.

  2. Scale-dependent segregation of seeders and resprouters in cork oak (Quercus suber) forests.

    Science.gov (United States)

    Coca, M; Pausas, J G

    2012-02-01

    Recent studies showed that disturbances and water availability determine the richness among plants with different post-fire strategies of Mediterranean-type ecosystems. The aim of this study was to determine whether or not the scale of analysis has an influence on the effects of these factors and, therefore, on the segregation of the dominant post-fire strategies, obligate seeders and obligate resprouters, and facultative species. We recorded all woody species and geographical features on 94 (75 m(2)) plots of cork oak woodlands in the southern Iberian Peninsula. For each regenerative type (resprouters, seeders and species with both traits--facultative species), we tested the relationship between the number of species and the predictors using a generalised linear mixed model. The fixed predictor considered at the large scale was altitude, and fixed predictors considered at the local scale were aspect (north/south) and disturbance (fire and clearing by heavy machinery; yes/no). The random predictor was the factor of site. When this factor did not have significant effect for some regenerative types, these relationships was tested using a generalised linear model. Resprouting species were most represented at lower altitudes and in undisturbed sites, while seeders were also at lower altitudes but mostly on south-facing slopes, especially south-facing disturbed sites. For facultative species, site is the most important variable. The proportion of seeders from the total species is not related to altitude, but it is related to disturbance and aspect. These results suggest that there is no segregation of the richness of seeders and resprouters at the large scale (altitudinal gradient). Differences appeared at the local scale (aspect and disturbance).

  3. Surface, segregation profile for Ni50Pd50(100)

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Ruban, Andrei; Skriver, Hans Lomholt

    1997-01-01

    A recent dynamical LEED study [G.N. Derry, C.B. McVey, P.J. Rous, Surf. Sci. 326 (1995) 59] reported an oscillatory surface segregation profile in the Ni50Pd50(100) system with the surface layer enriched by Pd. We have performed ab-initio total-energy calculations for the surface of this alloy...... system using the coherent potential approximation and obtain an oscillatory segregation profile, in agreement with experiments. We discuss the energetic origin of the oscillatory segregation profile in terms of effective cluster interactions. We include relaxation effects by means of the semi...

  4. The socioeconomic and ethnic segregation of living conditions in Copenhagen

    DEFF Research Database (Denmark)

    Møller, Iver Hornemann; Larsen, Jørgen Elm

    2015-01-01

    . Differences in income have increased spatial segregation in Copenhagen in terms of housing and education. This segregation is most visible in relation to highly educated Danes and immigrants from non-Western countries. The article first examines poverty at household level and its spatial dimensions. Secondly......The aim of this article is to analyze the discrepancies between certain aspects of living conditions of ethnic Danes and immigrants in Copenhagen. Copenhagen is quite prosperous and fares well in the globalized economy but is at the same time experiencing increasing poverty and ethnic segregation......, it considers other living conditions (for example social networks). Thirdly, it explores immigrants’ experiences of, among other things, education, employment and citizenship. It concludes that social cohesion in Copenhagen may be threatened if this segregation continues....

  5. The Socioeconomic and Ethnic Segregation of Living Conditions in Copenhagen

    DEFF Research Database (Denmark)

    Møller, Iver Hornemann; Larsen, Jørgen Elm

    2015-01-01

    . Differences in income have increased spatial segregation in Copenhagen in terms of housing and education. This segregation is most visible in relation to highly educated Danes and immigrants from non-Western countries. The article first examines poverty at household level and its spatial dimensions. Secondly......The aim of this article is to analyze the discrepancies between certain aspects of living conditions of ethnic Danes and immigrants in Copenhagen. Copenhagen is quite prosperous and fares well in the globalized economy but is at the same time experiencing increasing poverty and ethnic segregation......, it considers other living conditions (for example social networks). Thirdly, it explores immigrants’ experiences of, among other things, education, employment and citizenship. It concludes that social cohesion in Copenhagen may be threatened if this segregation continues....

  6. Schelling model of cell segregation based only on local information

    Science.gov (United States)

    Nielsen, Alexander Valentin; Gade, Annika Lund; Juul, Jeppe; Strandkvist, Charlotte

    2015-11-01

    While biological studies suggest that motility of cells is involved in cell segregation, few computational models have investigated this mechanism. We apply a simple Schelling model, modified to reflect biological conditions, demonstrating how differences in cell motility arising exclusively from differences in the composition of the local environment can be sufficient to drive segregation. The work presented here demonstrates that the segregation behavior observed in the original Schelling model is robust to a relaxation of the requirement for global information and that the Schelling model may yield insight in the context of biological systems. In the model, the time course of cell segregation follows a power law in accord with experimental observations and previous work.

  7. Prokaryotic DNA segregation by an actin-like filament

    DEFF Research Database (Denmark)

    Møller-Jensen, Jakob; Bugge Jensen, Rasmus; Löwe, Jan;

    2002-01-01

    The mechanisms responsible for prokaryotic DNA segregation are largely unknown. The partitioning locus (par) encoded by the Escherichia coli plasmid R1 actively segregates its replicon to daughter cells. We show here that the ParM ATPase encoded by par forms dynamic actin-like filaments with prop......The mechanisms responsible for prokaryotic DNA segregation are largely unknown. The partitioning locus (par) encoded by the Escherichia coli plasmid R1 actively segregates its replicon to daughter cells. We show here that the ParM ATPase encoded by par forms dynamic actin-like filaments...... point for ParM polymerization. Hence, we provide evidence for a simple prokaryotic analogue of the eukaryotic mitotic spindle apparatus....

  8. Dynamics of Escherichia coli Chromosome Segregation during Multifork Replication

    DEFF Research Database (Denmark)

    Nielsen, Henrik Jørck; Youngren, Brenda; Hansen, Flemming G.

    2007-01-01

    Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division...

  9. Auditory stream segregation in children with Asperger syndrome.

    Science.gov (United States)

    Lepistö, T; Kuitunen, A; Sussman, E; Saalasti, S; Jansson-Verkasalo, E; Nieminen-von Wendt, T; Kujala, T

    2009-12-01

    Individuals with Asperger syndrome (AS) often have difficulties in perceiving speech in noisy environments. The present study investigated whether this might be explained by deficient auditory stream segregation ability, that is, by a more basic difficulty in separating simultaneous sound sources from each other. To this end, auditory event-related brain potentials were recorded from a group of school-aged children with AS and a group of age-matched controls using a paradigm specifically developed for studying stream segregation. Differences in the amplitudes of ERP components were found between groups only in the stream segregation conditions and not for simple feature discrimination. The results indicated that children with AS have difficulties in segregating concurrent sound streams, which ultimately may contribute to the difficulties in speech-in-noise perception.

  10. Dynamics of Transformation from Segregation to Mixed Wealth Cities

    CERN Document Server

    Sahasranaman, Anand

    2016-01-01

    We model the dynamics of the Schelling model for agents described simply by a continuously distributed variable - wealth. Agents move to neighborhoods where their wealth is not lesser than that of some proportion of their neighbors, the threshold level. As in the case of the classic Schelling model where segregation obtains between two races, we find here that wealth-based segregation occurs and persists. However, introducing uncertainty into the decision to move - that is, with some probability, if agents are allowed to move even though the threshold level condition is contravened - we find that even for small proportions of such disallowed moves, the dynamics no longer yield segregation but instead sharply transition into a persistent mixed wealth distribution. We investigate the nature of this sharp transformation between segregated and mixed states, and find that it is because of a non-linear relationship between allowed moves and disallowed moves. For small increases in disallowed moves, there is a rapid...

  11. Organization of texture segregation processing in primate visual cortex.

    NARCIS (Netherlands)

    Lamme, V.A.F.; van Dijk, B.W.; Spekreijse, H.

    1993-01-01

    Investigated which cortical areas and layers are involved in global feature interactions underlying texture segregation in humans and monkeys. Visual stimulation was assessed with an electrostatic monitor, and scalp or intracortical recordings with electrodes were made. Signal processing and psychop

  12. CHROMOSOME SEGREGATION: NOVEL INSIGHTS INTO THE MECHANISM AND REGULATION

    Directory of Open Access Journals (Sweden)

    Miroslava Pozgajova

    2013-02-01

    Full Text Available A crucial feature of every healthy living organism is accurate segregation of chromosomes. Errors in this process may lead to aneuploidy, which is responsible for diverse genetic defects and diseases such as Down syndrome, miscarriages, cancer and others. Although, chromosome segregation has been studied intensively in the past, the exact mechanism of accurate chromosome segregation still remains unclear. Identification and characterization of proteins and protein complexes involved in this process is essential for understanding of processes that lead to chromosome missegregation. Basic molecular mechanism share common principles in animals, humans, plants and unicellular organisms; it is therefore possible to study these mechanisms in simple model organisms such as yeasts. The fission yeast Schizosaccharomyces pombe is an excellent model organism to study the function and regulation of chromosome segregation in both mitosis and meiosis.