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Sample records for landscape factors influencing

  1. Proximate and landscape factors influence grassland bird distributions

    USGS Publications Warehouse

    Cunningham, M.A.; Johnson, D.H.

    2006-01-01

    Ecologists increasingly recognize that birds can respond to features well beyond their normal areas of activity, but little is known about the relative importance of landscapes and proximate factors or about the scales of landscapes that influence bird distributions. We examined the influences of tree cover at both proximate and landscape scales on grassland birds, a group of birds of high conservation concern, in the Sheyenne National Grassland in North Dakota, USA. The Grassland contains a diverse array of grassland and woodland habitats. We surveyed breeding birds on 2015 100 m long transect segments during 2002 and 2003. We modeled the occurrence of 19 species in relation to habitat features (percentages of grassland, woodland, shrubland, and wetland) within each 100-m segment and to tree cover within 200-1600 m of the segment. We used information-theoretic statistical methods to compare models and variables. At the proximate scales, tree cover was the most important variable, having negative influences on 13 species and positive influences on two species. In a comparison of multiple scales, models with only proximate variables were adequate for some species, but models combining proximate with landscape information were best for 17 of 19 species. Landscape-only models were rarely competitive. Combined models at the largest scales (800-1600 m) were best for 12 of 19 species. Seven species had best models including 1600-m landscapes plus proximate factors in at least one year. These were Wilson's Phalarope (Phalaropus tricolor), Sedge Wren (Cistothorus platensis), Field Sparrow (Spizella pusilla), Grasshopper Sparrow (Ammodramus savannarum), Bobolink (Dolychonix oryzivorus), Red-winged Blackbird (Agelaius phoeniceus), and Brown-headed Cowbird (Molothrus ater). These seven are small-bodied species; thus larger-bodied species do not necessarily respond most to the largest landscapes. Our findings suggest that birds respond to habitat features at a variety of

  2. Proximate and landscape factors influence grassland bird distributions.

    PubMed

    Cunningham, Mary Ann; Johnson, Douglas H

    2006-06-01

    Ecologists increasingly recognize that birds can respond to features well beyond their normal areas of activity, but little is known about the relative importance of landscapes and proximate factors or about the scales of landscapes that influence bird distributions. We examined the influences of tree cover at both proximate and landscape scales on grassland birds, a group of birds of high conservation concern, in the Sheyenne National Grassland in North Dakota, USA. The Grassland contains a diverse array of grassland and woodland habitats. We surveyed breeding birds on 2015 100 m long transect segments during 2002 and 2003. We modeled the occurrence of 19 species in relation to habitat features (percentages of grassland, woodland, shrubland, and wetland) within each 100-m segment and to tree cover within 200-1600 m of the segment. We used information-theoretic statistical methods to compare models and variables. At the proximate scales, tree cover was the most important variable, having negative influences on 13 species and positive influences on two species. In a comparison of multiple scales, models with only proximate variables were adequate for some species, but models combining proximate with landscape information were best for 17 of 19 species. Landscape-only models were rarely competitive. Combined models at the largest scales (800-1600 m) were best for 12 of 19 species. Seven species had best models including 1600-m landscapes plus proximate factors in at least one year. These were Wilson's Phalarope (Phalaropus tricolor), Sedge Wren (Cistothorus platensis), Field Sparrow (Spizella pusilla), Grasshopper Sparrow (Ammodramus savannarum), Bobolink (Dolychonix oryzivorus), Red-winged Blackbird (Agelaius phoeniceus), and Brown-headed Cowbird (Molothrus ater). These seven are small-bodied species; thus larger-bodied species do not necessarily respond most to the largest landscapes. Our findings suggest that birds respond to habitat features at a variety of

  3. Influence of landscape-scale factors in limiting brook trout populations in Pennsylvania streams

    USGS Publications Warehouse

    Kocovsky, P.M.; Carline, R.F.

    2006-01-01

    Landscapes influence the capacity of streams to produce trout through their effect on water chemistry and other factors at the reach scale. Trout abundance also fluctuates over time; thus, to thoroughly understand how spatial factors at landscape scales affect trout populations, one must assess the changes in populations over time to provide a context for interpreting the importance of spatial factors. We used data from the Pennsylvania Fish and Boat Commission's fisheries management database to investigate spatial factors that affect the capacity of streams to support brook trout Salvelinus fontinalis and to provide models useful for their management. We assessed the relative importance of spatial and temporal variation by calculating variance components and comparing relative standard errors for spatial and temporal variation. We used binary logistic regression to predict the presence of harvestable-length brook trout and multiple linear regression to assess the mechanistic links between landscapes and trout populations and to predict population density. The variance in trout density among streams was equal to or greater than the temporal variation for several streams, indicating that differences among sites affect population density. Logistic regression models correctly predicted the absence of harvestable-length brook trout in 60% of validation samples. The r 2-value for the linear regression model predicting density was 0.3, indicating low predictive ability. Both logistic and linear regression models supported buffering capacity against acid episodes as an important mechanistic link between landscapes and trout populations. Although our models fail to predict trout densities precisely, their success at elucidating the mechanistic links between landscapes and trout populations, in concert with the importance of spatial variation, increases our understanding of factors affecting brook trout abundance and will help managers and private groups to protect and

  4. Landscape factors and hydrology influence mercury concentrations in wading birds breeding in the Florida Everglades, USA.

    PubMed

    Herring, Garth; Eagles-Smith, Collin A; Ackerman, Joshua T; Gawlik, Dale E; Beerens, James M

    2013-08-01

    The hydrology of wetland ecosystems is a key driver of both mercury (Hg) methylation and waterbird foraging ecology, and hence may play a fundamental role in waterbird exposure and risk to Hg contamination. However, few studies have investigated hydrological factors that influence waterbird Hg exposure. We examined how several landscape-level hydrological variables influenced Hg concentrations in great egret and white ibis adults and chicks in the Florida Everglades. The great egret is a visual "exploiter" species that tolerates lower prey densities and is less sensitive to hydrological conditions than is the white ibis, which is a tactile "searcher" species that pursues higher prey densities in shallow water. Mercury concentrations in adult great egrets were most influenced by the spatial region that they occupied in the Everglades (higher in the southern region); whereas the number of days a site was dry during the previous dry season was the most important factor influencing Hg concentrations in adult ibis (Hg concentrations increased with the number of days dry). In contrast, Hg concentrations in egret chicks were most influenced by calendar date (increasing with date), whereas Hg concentrations in ibis chicks were most influenced by chick age, region, and water recession rate (Hg concentrations decreased with age, were higher in the southern regions, and increased with positive water recession rates). Our results indicate that both recent (preceding two weeks) hydrological conditions, and those of the prior year, influence Hg concentrations in wading birds. Further, these results suggest that Hg exposure in wading birds is driven by complex relationships between wading bird behavior and life stage, landscape hydrologic patterns, and biogeochemical processes.

  5. Landscape factors and hydrology influence mercury concentrations in wading birds breeding in the Florida Everglades, USA

    USGS Publications Warehouse

    Herring, Garth; Eagles-Smith, Collin A.; Ackerman, Joshua T.; Gawlik, Dale E.; Beerens, James M.

    2013-01-01

    The hydrology of wetland ecosystems is a key driver of both mercury (Hg) methylation and waterbird foraging ecology, and hence may play a fundamental role in waterbird exposure and risk to Hg contamination. However, few studies have investigated hydrological factors that influence waterbird Hg exposure. We examined how several landscape-level hydrological variables influenced Hg concentrations in great egret and white ibis adults and chicks in the Florida Everglades. The great egret is a visual “exploiter” species that tolerates lower prey densities and is less sensitive to hydrological conditions than is the white ibis, which is a tactile “searcher” species that pursues higher prey densities in shallow water. Mercury concentrations in adult great egrets were most influenced by the spatial region that they occupied in the Everglades (higher in the southern region); whereas the number of days a site was dry during the previous dry season was the most important factor influencing Hg concentrations in adult ibis (Hg concentrations increased with the number of days dry). In contrast, Hg concentrations in egret chicks were most influenced by calendar date (increasing with date), whereas Hg concentrations in ibis chicks were most influenced by chick age, region, and water recession rate (Hg concentrations decreased with age, were higher in the southern regions, and increased with positive water recession rates). Our results indicate that both recent (preceding two weeks) hydrological conditions, and those of the prior year, influence Hg concentrations in wading birds. Further, these results suggest that Hg exposure in wading birds is driven by complex relationships between wading bird behavior and life stage, landscape hydrologic patterns, and biogeochemical processes.

  6. Multi-scale landscape factors influencing stream water quality in the state of Oregon.

    PubMed

    Nash, Maliha S; Heggem, Daniel T; Ebert, Donald; Wade, Timothy G; Hall, Robert K

    2009-09-01

    Enterococci bacteria are used to indicate the presence of human and/or animal fecal materials in surface water. In addition to human influences on the quality of surface water, a cattle grazing is a widespread and persistent ecological stressor in the Western United States. Cattle may affect surface water quality directly by depositing nutrients and bacteria, and indirectly by damaging stream banks or removing vegetation cover, which may lead to increased sediment loads. This study used the State of Oregon surface water data to determine the likelihood of animal pathogen presence using enterococci and analyzed the spatial distribution and relationship of biotic (enterococci) and abiotic (nitrogen and phosphorous) surface water constituents to landscape metrics and others (e.g. human use, percent riparian cover, natural covers, grazing, etc.). We used a grazing potential index (GPI) based on proximity to water, land ownership and forage availability. Mean and variability of GPI, forage availability, stream density and length, and landscape metrics were related to enterococci and many forms of nitrogen and phosphorous in standard and logistic regression models. The GPI did not have a significant role in the models, but forage related variables had significant contribution. Urban land use within stream reach was the main driving factor when exceeding the threshold (> or =35 cfu/100 ml), agriculture was the driving force in elevating enterococci in sites where enterococci concentration was <35 cfu/100 ml. Landscape metrics related to amount of agriculture, wetlands and urban all contributed to increasing nutrients in surface water but at different scales. The probability of having sites with concentrations of enterococci above the threshold was much lower in areas of natural land cover and much higher in areas with higher urban land use within 60 m of stream. A 1% increase in natural land cover was associated with a 12% decrease in the predicted odds of having a site

  7. Multi-scale Landscape Factors Influencing Stream Water Quality in the State of Oregon

    EPA Science Inventory

    Enterococci bacteria are used to indicate the presence of human and/or animal fecal materials in surface water. In addition to human influences on the quality of surface water, a cattle grazing is a widespread and persistent ecological stressor in the Western United States. Cattl...

  8. How landscape scale changes affect ecological processes in conservation areas: external factors influence land use by zebra (Equus burchelli) in the Okavango Delta.

    PubMed

    Bartlam-Brooks, Hattie L A; Bonyongo, Mpaphi C; Harris, Stephen

    2013-09-01

    Most large-bodied wildlife populations in sub-Saharan Africa only survive in conservation areas, but are continuing to decline because external changes influence ecological processes within reserves, leading to a lack of functionality. However, failure to understand how landscape scale changes influence ecological processes limits our ability to manage protected areas. We used GPS movement data to calculate dry season home ranges for 14 zebra mares in the Okavango Delta and investigated the effects of a range of landscape characteristics (number of habitat patches, mean patch shape, mean index of juxtaposition, and interspersion) on home range size. Resource utilization functions (RUF) were calculated to investigate how specific landscape characteristics affected space use. Space use by all zebra was clustered. In the wetter (Central) parts of the Delta home range size was negatively correlated with the density of habitat patches, more complex patch shapes, low juxtaposition of habitats and an increased availability of floodplain and grassland habitats. In the drier (Peripheral) parts of the Delta, higher use by zebra was also associated with a greater availability of floodplain and grassland habitats, but a lower density of patches and simpler patch shapes. The most important landscape characteristic was not consistent between zebra within the same area of the Delta, suggesting that no single foraging strategy is substantially superior to others, and so animals using different foraging strategies may all thrive. The distribution and complexity of habitat patches are crucial in determining space use by zebra. The extent and duration of seasonal flooding is the principal process affecting habitat patch characteristics in the Okavango Delta, particularly the availability of floodplains, which are the habitat at greatest risk from climate change and anthropogenic disturbance to the Okavango's catchment basin. Understanding how the factors that determine habitat

  9. Influence of landscape structure on reef fish assemblages

    USGS Publications Warehouse

    Grober-Dunsmore, R.; Frazer, T.K.; Beets, J.P.; Lindberg, W.J.; Zwick, P.; Funicelli, N.A.

    2008-01-01

    Management of tropical marine environments calls for interdisciplinary studies and innovative methodologies that consider processes occurring over broad spatial scales. We investigated relationships between landscape structure and reef fish assemblage structure in the US Virgin Islands. Measures of landscape structure were transformed into a reduced set of composite indices using principal component analyses (PCA) to synthesize data on the spatial patterning of the landscape structure of the study reefs. However, composite indices (e.g., habitat diversity) were not particularly informative for predicting reef fish assemblage structure. Rather, relationships were interpreted more easily when functional groups of fishes were related to individual habitat features. In particular, multiple reef fish parameters were strongly associated with reef context. Fishes responded to benthic habitat structure at multiple spatial scales, with various groups of fishes each correlated to a unique suite of variables. Accordingly, future experiments should be designed to test functional relationships based on the ecology of the organisms of interest. Our study demonstrates that landscape-scale habitat features influence reef fish communities, illustrating promise in applying a landscape ecology approach to better understand factors that structure coral reef ecosystems. Furthermore, our findings may prove useful in design of spatially-based conservation approaches such as marine protected areas (MPAs), because landscape-scale metrics may serve as proxies for areas with high species diversity and abundance within the coral reef landscape. ?? 2007 Springer Science+Business Media B.V.

  10. Landscape factors influencing the spatial distribution and abundance of mosquito vector Culex quinquefasciatus (Diptera: Culicidae) in a mixed residential-agricultural community in Hawai'i

    USGS Publications Warehouse

    Reiter, M.E.; Lapointe, D.A.

    2007-01-01

    Mosquito-borne avian diseases, principally avian malaria (Plasmodium relictum Grassi and Feletti) and avian pox (Avipoxvirus sp.) have been implicated as the key limiting factor associated with recent declines of endemic avifauna in the Hawaiian Island archipelago. We present data on the relative abundance, infection status, and spatial distribution of the primary mosquito vector Culex quinquefasciatus Say (Diptera: Culicidae) across a mixed, residential-agricultural community adjacent to Hawai'i Volcanoes National Park on Hawai'i Island. We modeled the effect of agriculture and forest fragmentation in determining relative abundance of adult Cx. quinquefasciatus in Volcano Village, and we implement our statistical model in a geographic information system to generate a probability of mosquito capture prediction surface for the study area. Our model was based on biweekly captures of adult mosquitoes from 20 locations within Volcano Village from October 2001 to April 2003. We used mixed effects logistic regression to model the probability of capturing a mosquito, and we developed a set of 17 competing models a priori to specifically evaluate the effect of agriculture and fragmentation (i.e., residential landscapes) at two spatial scales. In total, 2,126 mosquitoes were captured in CO 2-baited traps with an average probability of 0.27 (SE = 0.10) of capturing one or more mosquitoes per trap night. Twelve percent of mosquitoes captured were infected with P. relictum. Our data indicate that agricultural lands and forest fragmentation significantly increase the probability of mosquito capture. The prediction surface identified areas along the Hawai'i Volcanoes National Park boundary that may have high relative abundance of the vector. Our data document the potential of avian malaria transmission in residential-agricultural landscapes and support the need for vector management that extends beyond reserve boundaries and considers a reserve's spatial position in a highly

  11. Influence of landscape factors and management decisions on spatial and temporal patterns of the transmission of chronic wasting disease transmission in white-tailed deer.

    PubMed

    O'Hara Ruiz, Marilyn; Kelly, Amy C; Brown, William M; Novakofski, Jan E; Mateus-Pinilla, Nohra E

    2013-11-01

    Chronic wasting disease (CWD) has been reported in white-tailed deer at the border of the US states of Illinois and Wisconsin since 2002. Transmission of infectious prions between animals and from the environment has resulted in spatial and temporal structure observable in the spatio-temporal patterns of reported cases. Case locations of 382 positive cases from 28,954 deer tested between 2002 and 2009 provided insight into the potential risk factors and landscape features associated with transmission using a combination of clustering, generalised linear modelling and descriptive evaluations of a risk map of predicted cases of CWD. A species distribution map of white-tailed deer developed using MaxEnt provided an estimate of deer locations. We found that deer probability increased in areas with larger forests and less urban and agricultural lands. Spatial clustering analysis revealed a core area of persistent CWD transmission in the northern part of the region. The regression model indicated that larger and more compact forests were associated with higher risk for CWD. High risk areas also had soils with less clay and more sand than other parts of the region. The transmission potential was higher where landscape features indicated the potential for higher deer concentrations. The inclusion of spatial lag variables improved the model. Of the 102 cases reported in the study area in the two years following the study period, 89 (87%) of those were in the 32% of the study area with the highest 50% of predicted risk of cases. PMID:24258897

  12. Influence of landscape factors and management decisions on spatial and temporal patterns of the transmission of chronic wasting disease transmission in white-tailed deer.

    PubMed

    O'Hara Ruiz, Marilyn; Kelly, Amy C; Brown, William M; Novakofski, Jan E; Mateus-Pinilla, Nohra E

    2013-11-01

    Chronic wasting disease (CWD) has been reported in white-tailed deer at the border of the US states of Illinois and Wisconsin since 2002. Transmission of infectious prions between animals and from the environment has resulted in spatial and temporal structure observable in the spatio-temporal patterns of reported cases. Case locations of 382 positive cases from 28,954 deer tested between 2002 and 2009 provided insight into the potential risk factors and landscape features associated with transmission using a combination of clustering, generalised linear modelling and descriptive evaluations of a risk map of predicted cases of CWD. A species distribution map of white-tailed deer developed using MaxEnt provided an estimate of deer locations. We found that deer probability increased in areas with larger forests and less urban and agricultural lands. Spatial clustering analysis revealed a core area of persistent CWD transmission in the northern part of the region. The regression model indicated that larger and more compact forests were associated with higher risk for CWD. High risk areas also had soils with less clay and more sand than other parts of the region. The transmission potential was higher where landscape features indicated the potential for higher deer concentrations. The inclusion of spatial lag variables improved the model. Of the 102 cases reported in the study area in the two years following the study period, 89 (87%) of those were in the 32% of the study area with the highest 50% of predicted risk of cases.

  13. Landscape genetics in a changing world: disentangling historical and contemporary influences and inferring change.

    PubMed

    Epps, Clinton W; Keyghobadi, Nusha

    2015-12-01

    Landscape genetics seeks to determine the effect of landscape features on gene flow and genetic structure. Often, such analyses are intended to inform conservation and management. However, depending on the many factors that influence the time to reach equilibrium, genetic structure may more strongly represent past rather than contemporary landscapes. This well-known lag between current demographic processes and population genetic structure often makes it challenging to interpret how contemporary landscapes and anthropogenic activity shape gene flow. Here, we review the theoretical framework for factors that influence time lags, summarize approaches to address this temporal disconnect in landscape genetic studies, and evaluate ways to make inferences about landscape change and its effects on species using genetic data alone or in combination with other data. Those approaches include comparing correlation of genetic structure with historical versus contemporary landscapes, using molecular markers with different rates of evolution, contrasting metrics of genetic structure and gene flow that reflect population genetic processes operating at different temporal scales, comparing historical and contemporary samples, combining genetic data with contemporary estimates of species distribution or movement, and controlling for phylogeographic history. We recommend using simulated data sets to explore time lags in genetic structure, and argue that time lags should be explicitly considered both when designing and interpreting landscape genetic studies. We conclude that the time lag problem can be exploited to strengthen inferences about recent landscape changes and to establish conservation baselines, particularly when genetic data are combined with other data.

  14. Landscape influence on soil carbon and nutrient levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Past runoff, erosion, and management practices influence nutrient levels on the landscape. These starting levels affect future nutrient transport due to runoff, erosion, and leaching events. The purpose of this study was to examine closed-depression landscape effects on surface soil organic matter, ...

  15. Do geographically isolated wetlands influence landscape functions?

    PubMed

    Cohen, Matthew J; Creed, Irena F; Alexander, Laurie; Basu, Nandita B; Calhoun, Aram J K; Craft, Christopher; D'Amico, Ellen; DeKeyser, Edward; Fowler, Laurie; Golden, Heather E; Jawitz, James W; Kalla, Peter; Kirkman, L Katherine; Lane, Charles R; Lang, Megan; Leibowitz, Scott G; Lewis, David Bruce; Marton, John; McLaughlin, Daniel L; Mushet, David M; Raanan-Kiperwas, Hadas; Rains, Mark C; Smith, Lora; Walls, Susan C

    2016-02-23

    Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fraction of wetland edges where many functions are enhanced, and form complexes with other water bodies to create spatial and temporal heterogeneity in the timing, flow paths, and magnitude of network connectivity. These attributes signal a critical role for GIWs in sustaining a portfolio of landscape functions, but legal protections remain weak despite preferential loss from many landscapes. GIWs lack persistent surface water connections, but this condition does not imply the absence of hydrological, biogeochemical, and biological exchanges with nearby and downstream waters. Although hydrological and biogeochemical connectivity is often episodic or slow (e.g., via groundwater), hydrologic continuity and limited evaporative solute enrichment suggest both flow generation and solute and sediment retention. Similarly, whereas biological connectivity usually requires overland dispersal, numerous organisms, including many rare or threatened species, use both GIWs and downstream waters at different times or life stages, suggesting that GIWs are critical elements of landscape habitat mosaics. Indeed, weaker hydrologic connectivity with downstream waters and constrained biological connectivity with other landscape elements are precisely what enhances some GIW functions and enables others. Based on analysis of wetland geography and synthesis of wetland functions, we argue that sustaining landscape functions requires conserving the entire continuum of wetland connectivity, including GIWs.

  16. Do geographically isolated wetlands influence landscape functions?

    USGS Publications Warehouse

    Cohen, Matthew J.; Creed, Irena F.; Alexander, Laurie C.; Basu, Nandita; Calhoun, Aram J. K.; Craft, Christopher; D’Amico, Ellen; DeKeyser, Edward S.; Fowler, Laurie; Golden, Heather E.; Jawitz, James W.; Kalla, Peter; Kirkman, L. Katherine; Lane, Charles R.; Lang, Megan; Leibowitz, Scott G.; Lewis, David Bruce; Marton, John; McLaughlin, Daniel L.; Mushet, David M.; Raanan-Kiperwas, Hadas; Rains, Mark C.; Smith, Lora; Walls, Susan C.

    2015-01-01

    Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fraction of wetland edges where many functions are enhanced, and form complexes with other water bodies to create spatial and temporal heterogeneity in the timing, flow paths, and magnitude of network connectivity. These attributes signal a critical role for GIWs in sustaining a portfolio of landscape functions, but legal protections remain weak despite preferential loss from many landscapes. GIWs lack persistent surface water connections, but this condition does not imply the absence of hydrological, biogeochemical, and biological exchanges with nearby and downstream waters. Although hydrological and biogeochemical connectivity is often episodic or slow (e.g., via groundwater), hydrologic continuity and limited evaporative solute enrichment suggest both flow generation and solute and sediment retention. Similarly, whereas biological connectivity usually requires overland dispersal, numerous organisms, including many rare or threatened species, use both GIWs and downstream waters at different times or life stages, suggesting that GIWs are critical elements of landscape habitat mosaics. Indeed, weaker hydrologic connectivity with downstream waters and constrained biological connectivity with other landscape elements are precisely what enhances some GIW functions and enables others. Based on analysis of wetland geography and synthesis of wetland functions, we argue that sustaining landscape functions requires conserving the entire continuum of wetland connectivity, including GIWs.

  17. Do Geographically Isolated Wetlands Influence Landscape Functions?

    EPA Science Inventory

    Landscape functions such as flow generation, nutrient and sediment retention, and biodiversity support depend on the exchange of solutes, particles, energy, and organisms between elements in hydrological and habitat networks. Wetlands are important network elements, providing hyd...

  18. Landscape structure and climate influences on hydrologic response

    NASA Astrophysics Data System (ADS)

    Nippgen, Fabian; McGlynn, Brian L.; Marshall, Lucy A.; Emanuel, Ryan E.

    2011-12-01

    Climate variability and catchment structure (topography, geology, vegetation) have a significant influence on the timing and quantity of water discharged from mountainous catchments. How these factors combine to influence runoff dynamics is poorly understood. In this study we linked differences in hydrologic response across catchments and across years to metrics of landscape structure and climate using a simple transfer function rainfall-runoff modeling approach. A transfer function represents the internal catchment properties that convert a measured input (rainfall/snowmelt) into an output (streamflow). We examined modeled mean response time, defined as the average time that it takes for a water input to leave the catchment outlet from the moment it reaches the ground surface. We combined 12 years of precipitation and streamflow data from seven catchments in the Tenderfoot Creek Experimental Forest (Little Belt Mountains, southwestern Montana) with landscape analyses to quantify the first-order controls on mean response times. Differences between responses across the seven catchments were related to the spatial variability in catchment structure (e.g., slope, flowpath lengths, tree height). Annual variability was largely a function of maximum snow water equivalent. Catchment averaged runoff ratios exhibited strong correlations with mean response time while annually averaged runoff ratios were not related to climatic metrics. These results suggest that runoff ratios in snowmelt dominated systems are mainly controlled by topography and not by climatic variability. This approach provides a simple tool for assessing differences in hydrologic response across diverse watersheds and climate conditions.

  19. Do geographically isolated wetlands influence landscape functions?

    PubMed

    Cohen, Matthew J; Creed, Irena F; Alexander, Laurie; Basu, Nandita B; Calhoun, Aram J K; Craft, Christopher; D'Amico, Ellen; DeKeyser, Edward; Fowler, Laurie; Golden, Heather E; Jawitz, James W; Kalla, Peter; Kirkman, L Katherine; Lane, Charles R; Lang, Megan; Leibowitz, Scott G; Lewis, David Bruce; Marton, John; McLaughlin, Daniel L; Mushet, David M; Raanan-Kiperwas, Hadas; Rains, Mark C; Smith, Lora; Walls, Susan C

    2016-02-23

    Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fraction of wetland edges where many functions are enhanced, and form complexes with other water bodies to create spatial and temporal heterogeneity in the timing, flow paths, and magnitude of network connectivity. These attributes signal a critical role for GIWs in sustaining a portfolio of landscape functions, but legal protections remain weak despite preferential loss from many landscapes. GIWs lack persistent surface water connections, but this condition does not imply the absence of hydrological, biogeochemical, and biological exchanges with nearby and downstream waters. Although hydrological and biogeochemical connectivity is often episodic or slow (e.g., via groundwater), hydrologic continuity and limited evaporative solute enrichment suggest both flow generation and solute and sediment retention. Similarly, whereas biological connectivity usually requires overland dispersal, numerous organisms, including many rare or threatened species, use both GIWs and downstream waters at different times or life stages, suggesting that GIWs are critical elements of landscape habitat mosaics. Indeed, weaker hydrologic connectivity with downstream waters and constrained biological connectivity with other landscape elements are precisely what enhances some GIW functions and enables others. Based on analysis of wetland geography and synthesis of wetland functions, we argue that sustaining landscape functions requires conserving the entire continuum of wetland connectivity, including GIWs. PMID:26858425

  20. Do geographically isolated wetlands influence landscape functions?

    PubMed Central

    Cohen, Matthew J.; Creed, Irena F.; Alexander, Laurie; Basu, Nandita B.; Calhoun, Aram J. K.; Craft, Christopher; D’Amico, Ellen; DeKeyser, Edward; Fowler, Laurie; Golden, Heather E.; Jawitz, James W.; Kalla, Peter; Kirkman, L. Katherine; Lane, Charles R.; Lang, Megan; Leibowitz, Scott G.; Lewis, David Bruce; Marton, John; McLaughlin, Daniel L.; Mushet, David M.; Raanan-Kiperwas, Hadas; Rains, Mark C.; Smith, Lora; Walls, Susan C.

    2016-01-01

    Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fraction of wetland edges where many functions are enhanced, and form complexes with other water bodies to create spatial and temporal heterogeneity in the timing, flow paths, and magnitude of network connectivity. These attributes signal a critical role for GIWs in sustaining a portfolio of landscape functions, but legal protections remain weak despite preferential loss from many landscapes. GIWs lack persistent surface water connections, but this condition does not imply the absence of hydrological, biogeochemical, and biological exchanges with nearby and downstream waters. Although hydrological and biogeochemical connectivity is often episodic or slow (e.g., via groundwater), hydrologic continuity and limited evaporative solute enrichment suggest both flow generation and solute and sediment retention. Similarly, whereas biological connectivity usually requires overland dispersal, numerous organisms, including many rare or threatened species, use both GIWs and downstream waters at different times or life stages, suggesting that GIWs are critical elements of landscape habitat mosaics. Indeed, weaker hydrologic connectivity with downstream waters and constrained biological connectivity with other landscape elements are precisely what enhances some GIW functions and enables others. Based on analysis of wetland geography and synthesis of wetland functions, we argue that sustaining landscape functions requires conserving the entire continuum of wetland connectivity, including GIWs. PMID:26858425

  1. Influence of interspecific competition and landscape structure on spatial homogenization of avian assemblages.

    PubMed

    Robertson, Oliver J; McAlpine, Clive; House, Alan; Maron, Martine

    2013-01-01

    Human-induced biotic homogenization resulting from landscape change and increased competition from widespread generalists or 'winners', is widely recognized as a global threat to biodiversity. However, it remains unclear what aspects of landscape structure influence homogenization. This paper tests the importance of interspecific competition and landscape structure, for the spatial homogeneity of avian assemblages within a fragmented agricultural landscape of eastern Australia. We used field observations of the density of 128 diurnal bird species to calculate taxonomic and functional similarity among assemblages. We then examined whether taxonomic and functional similarity varied with patch type, the extent of woodland habitat, land-use intensity, habitat subdivision, and the presence of Manorina colonies (a competitive genus of honeyeaters). We found the presence of a Manorina colony was the most significant factor positively influencing both taxonomic and functional similarity of bird assemblages. Competition from members of this widespread genus of native honeyeater, rather than landscape structure, was the main cause of both taxonomic and functional homogenization. These species have not recently expanded their range, but rather have increased in density in response to agricultural landscape change. The negative impacts of Manorina honeyeaters on assemblage similarity were most pronounced in landscapes of moderate land-use intensity. We conclude that in these human-modified landscapes, increased competition from dominant native species, or 'winners', can result in homogeneous avian assemblages and the loss of specialist species. These interacting processes make biotic homogenization resulting from land-use change a global threat to biodiversity in modified agro-ecosystems.

  2. Monitoring landscape influence on nearshore condition

    EPA Science Inventory

    A major source of stress to the Great Lakes comes from tributary and landscape run-off. The large number of watersheds and the disparate landuse within them create variability in the tributary input along the extent of the nearshore. Identifying the local or regional response t...

  3. Trait-specific responses of wild bee communities to landscape composition, configuration and local factors.

    PubMed

    Hopfenmüller, Sebastian; Steffan-Dewenter, Ingolf; Holzschuh, Andrea

    2014-01-01

    Land-use intensification and loss of semi-natural habitats have induced a severe decline of bee diversity in agricultural landscapes. Semi-natural habitats like calcareous grasslands are among the most important bee habitats in central Europe, but they are threatened by decreasing habitat area and quality, and by homogenization of the surrounding landscape affecting both landscape composition and configuration. In this study we tested the importance of habitat area, quality and connectivity as well as landscape composition and configuration on wild bees in calcareous grasslands. We made detailed trait-specific analyses as bees with different traits might differ in their response to the tested factors. Species richness and abundance of wild bees were surveyed on 23 calcareous grassland patches in Southern Germany with independent gradients in local and landscape factors. Total wild bee richness was positively affected by complex landscape configuration, large habitat area and high habitat quality (i.e. steep slopes). Cuckoo bee richness was positively affected by complex landscape configuration and large habitat area whereas habitat specialists were only affected by the local factors habitat area and habitat quality. Small social generalists were positively influenced by habitat area whereas large social generalists (bumblebees) were positively affected by landscape composition (high percentage of semi-natural habitats). Our results emphasize a strong dependence of habitat specialists on local habitat characteristics, whereas cuckoo bees and bumblebees are more likely affected by the surrounding landscape. We conclude that a combination of large high-quality patches and heterogeneous landscapes maintains high bee species richness and communities with diverse trait composition. Such diverse communities might stabilize pollination services provided to crops and wild plants on local and landscape scales.

  4. Trait-specific responses of wild bee communities to landscape composition, configuration and local factors.

    PubMed

    Hopfenmüller, Sebastian; Steffan-Dewenter, Ingolf; Holzschuh, Andrea

    2014-01-01

    Land-use intensification and loss of semi-natural habitats have induced a severe decline of bee diversity in agricultural landscapes. Semi-natural habitats like calcareous grasslands are among the most important bee habitats in central Europe, but they are threatened by decreasing habitat area and quality, and by homogenization of the surrounding landscape affecting both landscape composition and configuration. In this study we tested the importance of habitat area, quality and connectivity as well as landscape composition and configuration on wild bees in calcareous grasslands. We made detailed trait-specific analyses as bees with different traits might differ in their response to the tested factors. Species richness and abundance of wild bees were surveyed on 23 calcareous grassland patches in Southern Germany with independent gradients in local and landscape factors. Total wild bee richness was positively affected by complex landscape configuration, large habitat area and high habitat quality (i.e. steep slopes). Cuckoo bee richness was positively affected by complex landscape configuration and large habitat area whereas habitat specialists were only affected by the local factors habitat area and habitat quality. Small social generalists were positively influenced by habitat area whereas large social generalists (bumblebees) were positively affected by landscape composition (high percentage of semi-natural habitats). Our results emphasize a strong dependence of habitat specialists on local habitat characteristics, whereas cuckoo bees and bumblebees are more likely affected by the surrounding landscape. We conclude that a combination of large high-quality patches and heterogeneous landscapes maintains high bee species richness and communities with diverse trait composition. Such diverse communities might stabilize pollination services provided to crops and wild plants on local and landscape scales. PMID:25137311

  5. Soil creep as factor of landscape change

    NASA Astrophysics Data System (ADS)

    Lucke, Bernhard

    2016-04-01

    Many erosion models assume that soils are transported grain-by-grain, and thus calculate loss and deposition according to parameters such as bulk density and average grain size. However, there are indications that clay-rich soils, such as the widespread Red Mediterranean Soils or Terrae Rossae, behave differently. This is illustrated by a case study of historic landscape changes in Jordan, where evidence for soil creep as main process of soil movement was found in the context of ancient cemeteries. Due to a dominance of smectites, the Red Mediterranean Soils in this area shrink and form cracks during the dry period. Because of the cracks and underlying limestone karst, they can swallow strong rains without high erosion risk. However, when water-saturated, these soils expand and can start creeping. Buried geoarchaeological features like small water channels on formerly cleared rocks suggest that soils can move a few cm uplslope when wet, and buried graves illustrate that soil creep can create new level surfaces, sealing cavities but not completely filling them. Such processes seem associated with slumping and earth flows as instable rocks might collapse under the weight of a creeping soil. While it is very difficult to measure such processes, landscape archaeology offers at least an indirect approach that could be suited to estimate the scale and impact of soil creep. Analogies with modern rainfalls, including record levels of precipitation during the winter 1991/1992, indicate that similar levels of soil moisture have not been reached during times of modern instrumental rainfall monitoring. This suggests that very strong deluges must have occurred during historical periods, that could potentially cause tremendous damage to modern infrastructure if happening again.

  6. Influence of Interspecific Competition and Landscape Structure on Spatial Homogenization of Avian Assemblages

    PubMed Central

    Robertson, Oliver J.; McAlpine, Clive; House, Alan; Maron, Martine

    2013-01-01

    Human-induced biotic homogenization resulting from landscape change and increased competition from widespread generalists or ‘winners’, is widely recognized as a global threat to biodiversity. However, it remains unclear what aspects of landscape structure influence homogenization. This paper tests the importance of interspecific competition and landscape structure, for the spatial homogeneity of avian assemblages within a fragmented agricultural landscape of eastern Australia. We used field observations of the density of 128 diurnal bird species to calculate taxonomic and functional similarity among assemblages. We then examined whether taxonomic and functional similarity varied with patch type, the extent of woodland habitat, land-use intensity, habitat subdivision, and the presence of Manorina colonies (a competitive genus of honeyeaters). We found the presence of a Manorina colony was the most significant factor positively influencing both taxonomic and functional similarity of bird assemblages. Competition from members of this widespread genus of native honeyeater, rather than landscape structure, was the main cause of both taxonomic and functional homogenization. These species have not recently expanded their range, but rather have increased in density in response to agricultural landscape change. The negative impacts of Manorina honeyeaters on assemblage similarity were most pronounced in landscapes of moderate land-use intensity. We conclude that in these human-modified landscapes, increased competition from dominant native species, or ‘winners’, can result in homogeneous avian assemblages and the loss of specialist species. These interacting processes make biotic homogenization resulting from land-use change a global threat to biodiversity in modified agro-ecosystems. PMID:23724136

  7. Influence of interspecific competition and landscape structure on spatial homogenization of avian assemblages.

    PubMed

    Robertson, Oliver J; McAlpine, Clive; House, Alan; Maron, Martine

    2013-01-01

    Human-induced biotic homogenization resulting from landscape change and increased competition from widespread generalists or 'winners', is widely recognized as a global threat to biodiversity. However, it remains unclear what aspects of landscape structure influence homogenization. This paper tests the importance of interspecific competition and landscape structure, for the spatial homogeneity of avian assemblages within a fragmented agricultural landscape of eastern Australia. We used field observations of the density of 128 diurnal bird species to calculate taxonomic and functional similarity among assemblages. We then examined whether taxonomic and functional similarity varied with patch type, the extent of woodland habitat, land-use intensity, habitat subdivision, and the presence of Manorina colonies (a competitive genus of honeyeaters). We found the presence of a Manorina colony was the most significant factor positively influencing both taxonomic and functional similarity of bird assemblages. Competition from members of this widespread genus of native honeyeater, rather than landscape structure, was the main cause of both taxonomic and functional homogenization. These species have not recently expanded their range, but rather have increased in density in response to agricultural landscape change. The negative impacts of Manorina honeyeaters on assemblage similarity were most pronounced in landscapes of moderate land-use intensity. We conclude that in these human-modified landscapes, increased competition from dominant native species, or 'winners', can result in homogeneous avian assemblages and the loss of specialist species. These interacting processes make biotic homogenization resulting from land-use change a global threat to biodiversity in modified agro-ecosystems. PMID:23724136

  8. Identification of landscape features influencing gene flow: How useful are habitat selection models?

    USGS Publications Warehouse

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

    2016-01-01

    Understanding how dispersal patterns are influenced by landscape heterogeneity is critical for modeling species connectivity. Resource selection function (RSF) models are increasingly used in landscape genetics approaches. However, because the ecological factors that drive habitat selection may be different from those influencing dispersal and gene flow, it is important to consider explicit assumptions and spatial scales of measurement. We calculated pairwise genetic distance among 301 Dall's sheep (Ovis dalli dalli) in southcentral Alaska using an intensive noninvasive sampling effort and 15 microsatellite loci. We used multiple regression of distance matrices to assess the correlation of pairwise genetic distance and landscape resistance derived from an RSF, and combinations of landscape features hypothesized to influence dispersal. Dall's sheep gene flow was positively correlated with steep slopes, moderate peak normalized difference vegetation indices (NDVI), and open land cover. Whereas RSF covariates were significant in predicting genetic distance, the RSF model itself was not significantly correlated with Dall's sheep gene flow, suggesting that certain habitat features important during summer (rugged terrain, mid-range elevation) were not influential to effective dispersal. This work underscores that consideration of both habitat selection and landscape genetics models may be useful in developing management strategies to both meet the immediate survival of a species and allow for long-term genetic connectivity.

  9. Identification of landscape features influencing gene flow: How useful are habitat selection models?

    PubMed

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

    2016-07-01

    Understanding how dispersal patterns are influenced by landscape heterogeneity is critical for modeling species connectivity. Resource selection function (RSF) models are increasingly used in landscape genetics approaches. However, because the ecological factors that drive habitat selection may be different from those influencing dispersal and gene flow, it is important to consider explicit assumptions and spatial scales of measurement. We calculated pairwise genetic distance among 301 Dall's sheep (Ovis dalli dalli) in southcentral Alaska using an intensive noninvasive sampling effort and 15 microsatellite loci. We used multiple regression of distance matrices to assess the correlation of pairwise genetic distance and landscape resistance derived from an RSF, and combinations of landscape features hypothesized to influence dispersal. Dall's sheep gene flow was positively correlated with steep slopes, moderate peak normalized difference vegetation indices (NDVI), and open land cover. Whereas RSF covariates were significant in predicting genetic distance, the RSF model itself was not significantly correlated with Dall's sheep gene flow, suggesting that certain habitat features important during summer (rugged terrain, mid-range elevation) were not influential to effective dispersal. This work underscores that consideration of both habitat selection and landscape genetics models may be useful in developing management strategies to both meet the immediate survival of a species and allow for long-term genetic connectivity.

  10. Identification of landscape features influencing gene flow: How useful are habitat selection models?

    PubMed

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

    2016-07-01

    Understanding how dispersal patterns are influenced by landscape heterogeneity is critical for modeling species connectivity. Resource selection function (RSF) models are increasingly used in landscape genetics approaches. However, because the ecological factors that drive habitat selection may be different from those influencing dispersal and gene flow, it is important to consider explicit assumptions and spatial scales of measurement. We calculated pairwise genetic distance among 301 Dall's sheep (Ovis dalli dalli) in southcentral Alaska using an intensive noninvasive sampling effort and 15 microsatellite loci. We used multiple regression of distance matrices to assess the correlation of pairwise genetic distance and landscape resistance derived from an RSF, and combinations of landscape features hypothesized to influence dispersal. Dall's sheep gene flow was positively correlated with steep slopes, moderate peak normalized difference vegetation indices (NDVI), and open land cover. Whereas RSF covariates were significant in predicting genetic distance, the RSF model itself was not significantly correlated with Dall's sheep gene flow, suggesting that certain habitat features important during summer (rugged terrain, mid-range elevation) were not influential to effective dispersal. This work underscores that consideration of both habitat selection and landscape genetics models may be useful in developing management strategies to both meet the immediate survival of a species and allow for long-term genetic connectivity. PMID:27330556

  11. Fitness landscapes among many options under social influence.

    PubMed

    Caiado, Camila C S; Brock, William A; Bentley, R Alexander; O'Brien, Michael J

    2016-09-21

    Cultural learning represents a novel problem in that an optimal decision depends not only on intrinsic utility of the decision/behavior but also on transparency of costs and benefits, the degree of social versus individual learning, and the relative popularity of each possible choice in a population. In terms of a fitness-landscape function, this recursive relationship means that multiple equilibria can exist. Here we use discrete-choice theory to construct a fitness-landscape function for a bi-axial decision-making map that plots the magnitude of social influence in the learning process against the costs and payoffs of decisions. Specifically, we use econometric and statistical methods to estimate not only the fitness function but also movements along the map axes. To search for these equilibria, we employ a hill-climbing algorithm that leads to the expected values of optimal decisions, which we define as peaks on the fitness landscape. We illustrate how estimation of a measure of transparency, a measure of social influence, and the associated fitness landscape can be accomplished using panel data sets. PMID:26851173

  12. Fitness landscapes among many options under social influence.

    PubMed

    Caiado, Camila C S; Brock, William A; Bentley, R Alexander; O'Brien, Michael J

    2016-09-21

    Cultural learning represents a novel problem in that an optimal decision depends not only on intrinsic utility of the decision/behavior but also on transparency of costs and benefits, the degree of social versus individual learning, and the relative popularity of each possible choice in a population. In terms of a fitness-landscape function, this recursive relationship means that multiple equilibria can exist. Here we use discrete-choice theory to construct a fitness-landscape function for a bi-axial decision-making map that plots the magnitude of social influence in the learning process against the costs and payoffs of decisions. Specifically, we use econometric and statistical methods to estimate not only the fitness function but also movements along the map axes. To search for these equilibria, we employ a hill-climbing algorithm that leads to the expected values of optimal decisions, which we define as peaks on the fitness landscape. We illustrate how estimation of a measure of transparency, a measure of social influence, and the associated fitness landscape can be accomplished using panel data sets.

  13. [Influence of Landscape Heterogeneity on Total Nitrogen Concentration in Zhongtian River Watershed].

    PubMed

    Wang, Jing-ping; Li, Zhao-fu; Liu, Hong-yu; Wang, Gang; Xin, Qiang

    2016-02-15

    Nutrient loading into rivers is generally changed by human-induced land use changes and can lead to surface water quality changes. Understanding the extent to which landscape heterogeneity influences nutrient loading is critical to the development of best management practices aimed at water-quality improvement. In this study, the year-round concentrations of total nitrogen were monitored from January 2013 to December 2013 in the 20 hydrological stations of Zhongtian River. Considering the nested relationship of watershed unit, seven land use structures and 13 landscape pattern indexes were chosen, and Pearson correlation analysis, principal component analysis and multiple regression analysis were used to explore the effects of land use pattern on total nitrogen concentrations in Zhongtian River. The results showed that: (1) Construction land and grasslands had a significant impact on total nitrogen concentration, construction land would worsen the water quality, while grasslands could improve water quality; (2) Landscape patch- shape index, landscape patch-area index and construction land were the main factors affecting the total nitrogen concentration in landscape scale; (3) Regression analysis showed that the construction land and landscape patch-area index contributions to total nitrogen concentrations were 67.31% and 32.69%, respectively. PMID:27363140

  14. [Influence of Landscape Heterogeneity on Total Nitrogen Concentration in Zhongtian River Watershed].

    PubMed

    Wang, Jing-ping; Li, Zhao-fu; Liu, Hong-yu; Wang, Gang; Xin, Qiang

    2016-02-15

    Nutrient loading into rivers is generally changed by human-induced land use changes and can lead to surface water quality changes. Understanding the extent to which landscape heterogeneity influences nutrient loading is critical to the development of best management practices aimed at water-quality improvement. In this study, the year-round concentrations of total nitrogen were monitored from January 2013 to December 2013 in the 20 hydrological stations of Zhongtian River. Considering the nested relationship of watershed unit, seven land use structures and 13 landscape pattern indexes were chosen, and Pearson correlation analysis, principal component analysis and multiple regression analysis were used to explore the effects of land use pattern on total nitrogen concentrations in Zhongtian River. The results showed that: (1) Construction land and grasslands had a significant impact on total nitrogen concentration, construction land would worsen the water quality, while grasslands could improve water quality; (2) Landscape patch- shape index, landscape patch-area index and construction land were the main factors affecting the total nitrogen concentration in landscape scale; (3) Regression analysis showed that the construction land and landscape patch-area index contributions to total nitrogen concentrations were 67.31% and 32.69%, respectively.

  15. The Influence of Evolution on Population Spread through Patchy Landscapes.

    PubMed

    Williams, Jennifer L; Snyder, Robin E; Levine, Jonathan M

    2016-07-01

    Predicting the spatial advance of biological invasions and range-shifting native species under climate change requires understanding how evolutionary processes influence the velocity of spread. Although landscape heterogeneity and the finite nature of individuals are known to influence the ecological dynamics of spreading populations, their effect on evolutionary dynamics influencing spread is poorly understood. We used adaptive dynamics and simulation approaches to evaluate the direction of selection on demographic and competitive traits in annual plant populations spreading through linear landscapes. In contrast to models in homogeneous environments where low-density fecundity is selectively favored, we found that large gaps between suitable habitat could favor the rise of competitively tolerant individuals at the invasion front, even when this ability to tolerate competitors came at the cost of reduced fecundity when rare. Simulations of the same processes incorporating finite individuals revealed a spatial priority effect; the long-term outcome of evolution strongly depended on which strategy initially got ahead. Finally, we found that although evolutionary change in demographic and competitive traits could increase the spread velocity, this increase could be insignificant in patchy landscapes, where competitive traits were favored in both spreading and nonspreading populations. PMID:27322118

  16. Spatial heterogeneity in landscape structure influences dispersal and genetic structure: empirical evidence from a grasshopper in an agricultural landscape.

    PubMed

    Gauffre, Bertrand; Mallez, Sophie; Chapuis, Marie-Pierre; Leblois, Raphael; Litrico, Isabelle; Delaunay, Sabrina; Badenhausser, Isabelle

    2015-04-01

    Dispersal may be strongly influenced by landscape and habitat characteristics that could either enhance or restrict movements of organisms. Therefore, spatial heterogeneity in landscape structure could influence gene flow and the spatial structure of populations. In the past decades, agricultural intensification has led to the reduction in grassland surfaces, their fragmentation and intensification. As these changes are not homogeneously distributed in landscapes, they have resulted in spatial heterogeneity with generally less intensified hedged farmland areas remaining alongside streams and rivers. In this study, we assessed spatial pattern of abundance and population genetic structure of a flightless grasshopper species, Pezotettix giornae, based on the surveys of 363 grasslands in a 430-km² agricultural landscape of western France. Data were analysed using geostatistics and landscape genetics based on microsatellites markers and computer simulations. Results suggested that small-scale intense dispersal allows this species to survive in intensive agricultural landscapes. A complex spatial genetic structure related to landscape and habitat characteristics was also detected. Two P. giornae genetic clusters bisected by a linear hedged farmland were inferred from clustering analyses. This linear hedged farmland was characterized by high hedgerow and grassland density as well as higher grassland temporal stability that were suspected to slow down dispersal. Computer simulations demonstrated that a linear-shaped landscape feature limiting dispersal could be detected as a barrier to gene flow and generate the observed genetic pattern. This study illustrates the relevance of using computer simulations to test hypotheses in landscape genetics studies.

  17. Anthropogenic influence on forest landscape in the Khumbu valley, Nepal

    NASA Astrophysics Data System (ADS)

    Lingua, Emanuele; Garbarino, Matteo; Urbinati, Carlo; Carrer, Marco

    2013-04-01

    High altitude Himalayan regions are geo-dynamically very active and very sensitive to natural and anthropogenic disturbances due to their steep slopes, variations of precipitations with elevation and short growing periods. Nonetheless, even in this remote region human pressure is often the most important factor affecting forest landscape. In the last decades the firewood demand has increased each year between September to December. The increase in the number of tourists, mountaineering, guides, porters, carpenters, lodges lead to a peak in the use of fuelwood. In order to understand anthropogenic impacts on forest, resources landscape and stand scale dynamics were analyzed in the Sagarmatha National Park (SNP) and its Buffer Zone in the Khumbu Valley (Nepal, Eastern Himalaya). Biological and historical data sources were employed, and a multi-scale approach was adopted to capture the influence of human activities on the distribution of tree species and forest structure. Stand structure and a range of environmental variables were sampled in 197 20x20 m square plots, and land use and anthropogenic variables were derived in a GIS environment (thematic maps and IKONOS, Landsat and Terra ASTER satellite images). We used multivariate statistical analyses to relate forest structure, anthropogenic influences, land uses, and topography. Fuel wood is the prime source of energy for cooking (1480-1880 Kg/person/year) and Quercus semecarpifolia, Rhododendron arboreum and Pinus wallichiana, among the others, are the most exploited species. Due to lack of sufficient energy sources deforestation is becoming a problem in the area. This might be a major threat causing soil erosion, landslides and other natural hazards. Among the 25 species of trees that were found in the Buffer Zone Community Forests of SNP, Pinus wallichiana, Lyonia ovalifolia, Quercus semecarpifolia and Rhododendron arboreum are the dominant species. The total stand density ranged from 228 to 379 tree/ha and the

  18. Landscape features influence postrelease predation on endangered black-footed ferrets

    USGS Publications Warehouse

    Poessel, S.A.; Breck, S.W.; Biggins, D.E.; Livieri, T.M.; Crooks, K.R.; Angeloni, L.

    2011-01-01

    Predation can be a critical factor influencing recovery of endangered species. In most recovery efforts lethal and nonlethal influences of predators are not sufficiently understood to allow prediction of predation risk, despite its importance. We investigated whether landscape features could be used to model predation risk from coyotes (Canis latrans) and great horned owls (Bubo virginianus) on the endangered black-footed ferret (Mustela nigripes). We used location data of reintroduced ferrets from 3 sites in South Dakota to determine whether exposure to landscape features typically associated with predators affected survival of ferrets, and whether ferrets considered predation risk when choosing habitat near perches potentially used by owls or near linear features predicted to be used by coyotes. Exposure to areas near likely owl perches reduced ferret survival, but landscape features potentially associated with coyote movements had no appreciable effect on survival. Ferrets were located within 90 m of perches more than expected in 2 study sites that also had higher ferret mortality due to owl predation. Densities of potential coyote travel routes near ferret locations were no different than expected in all 3 sites. Repatriated ferrets might have selected resources based on factors other than predator avoidance. Considering an easily quantified landscape feature (i.e., owl perches) can enhance success of reintroduction efforts for ferrets. Nonetheless, development of predictive models of predation risk and management strategies to mitigate that risk is not necessarily straightforward for more generalist predators such as coyotes. ?? 2011 American Society of Mammalogists.

  19. Climatic and Landscape Influences on Fire Regimes from 1984 to 2010 in the Western United States.

    PubMed

    Liu, Zhihua; Wimberly, Michael C

    2015-01-01

    An improved understanding of the relative influences of climatic and landscape controls on multiple fire regime components is needed to enhance our understanding of modern fire regimes and how they will respond to future environmental change. To address this need, we analyzed the spatio-temporal patterns of fire occurrence, size, and severity of large fires (> 405 ha) in the western United States from 1984-2010. We assessed the associations of these fire regime components with environmental variables, including short-term climate anomalies, vegetation type, topography, and human influences, using boosted regression tree analysis. Results showed that large fire occurrence, size, and severity each exhibited distinctive spatial and spatio-temporal patterns, which were controlled by different sets of climate and landscape factors. Antecedent climate anomalies had the strongest influences on fire occurrence, resulting in the highest spatial synchrony. In contrast, climatic variability had weaker influences on fire size and severity and vegetation types were the most important environmental determinants of these fire regime components. Topography had moderately strong effects on both fire occurrence and severity, and human influence variables were most strongly associated with fire size. These results suggest a potential for the emergence of novel fire regimes due to the responses of fire regime components to multiple drivers at different spatial and temporal scales. Next-generation approaches for projecting future fire regimes should incorporate indirect climate effects on vegetation type changes as well as other landscape effects on multiple components of fire regimes.

  20. Climatic and Landscape Influences on Fire Regimes from 1984 to 2010 in the Western United States

    PubMed Central

    Liu, Zhihua; Wimberly, Michael C.

    2015-01-01

    An improved understanding of the relative influences of climatic and landscape controls on multiple fire regime components is needed to enhance our understanding of modern fire regimes and how they will respond to future environmental change. To address this need, we analyzed the spatio-temporal patterns of fire occurrence, size, and severity of large fires (> 405 ha) in the western United States from 1984–2010. We assessed the associations of these fire regime components with environmental variables, including short-term climate anomalies, vegetation type, topography, and human influences, using boosted regression tree analysis. Results showed that large fire occurrence, size, and severity each exhibited distinctive spatial and spatio-temporal patterns, which were controlled by different sets of climate and landscape factors. Antecedent climate anomalies had the strongest influences on fire occurrence, resulting in the highest spatial synchrony. In contrast, climatic variability had weaker influences on fire size and severity and vegetation types were the most important environmental determinants of these fire regime components. Topography had moderately strong effects on both fire occurrence and severity, and human influence variables were most strongly associated with fire size. These results suggest a potential for the emergence of novel fire regimes due to the responses of fire regime components to multiple drivers at different spatial and temporal scales. Next-generation approaches for projecting future fire regimes should incorporate indirect climate effects on vegetation type changes as well as other landscape effects on multiple components of fire regimes. PMID:26465959

  1. Spatially Explicit Analysis of Metal Transfer to Biota: Influence of Soil Contamination and Landscape

    PubMed Central

    Fritsch, Clémentine; Cœurdassier, Michaël; Giraudoux, Patrick; Raoul, Francis; Douay, Francis; Rieffel, Dominique; de Vaufleury, Annette; Scheifler, Renaud

    2011-01-01

    Concepts and developments for a new field in ecotoxicology, referred to as “landscape ecotoxicology,” were proposed in the 1990s; however, to date, few studies have been developed in this emergent field. In fact, there is a strong interest in developing this area, both for renewing the concepts and tools used in ecotoxicology as well as for responding to practical issues, such as risk assessment. The aim of this study was to investigate the spatial heterogeneity of metal bioaccumulation in animals in order to identify the role of spatially explicit factors, such as landscape as well as total and extractable metal concentrations in soils. Over a smelter-impacted area, we studied the accumulation of trace metals (TMs: Cd, Pb and Zn) in invertebrates (the grove snail Cepaea sp and the glass snail Oxychilus draparnaudi) and vertebrates (the bank vole Myodes glareolus and the greater white-toothed shrew Crocidura russula). Total and CaCl2-extractable concentrations of TMs were measured in soils from woody patches where the animals were captured. TM concentrations in animals exhibited a high spatial heterogeneity. They increased with soil pollution and were better explained by total rather than CaCl2-extractable TM concentrations, except in Cepaea sp. TM levels in animals and their variations along the pollution gradient were modulated by the landscape, and this influence was species and metal specific. Median soil metal concentrations (predicted by universal kriging) were calculated in buffers of increasing size and were related to bioaccumulation. The spatial scale at which TM concentrations in animals and soils showed the strongest correlations varied between metals, species and landscapes. The potential underlying mechanisms of landscape influence (community functioning, behaviour, etc.) are discussed. Present results highlight the need for the further development of landscape ecotoxicology and multi-scale approaches, which would enhance our understanding of

  2. [Dynamics of ecological landscape pattern and its affecting factors in desert-oasis in Fukang, Xinjiang].

    PubMed

    Liu, Xinchun; Zhang, Yuandong; Ren, Guangyao; Pan, Xiaoling; He, Qing

    2004-07-01

    The spatial pattern of ecological landscape during land utilization in Fukang is heavily influenced by natural difference and the scale of water and land resource development. Analyses on the spatial pattern based on different zones and indexes showed that from 1987 to 1998, the change of the spatial pattern of ecological landscape during land utilization in Fukang was mainly the increase of plantation area in pluvial fan and the decrease in alluvial plain. The case was on the contrary about badlands. The acreage of woodland decreased in lower mountains, uplands and alluvial plain, but no variety in alluvial plain. The acreage of grassland increased in lower mountains and uplands, while decreased in other fields. The acreage of town increased in each sample field, while that of water area remained uncharged. The landscape diversity and evenness was descending, the dominance was ascending in lower mountains and in pluvial fan, while it was reverse in alluvial plain. Accessorial fragmentation showed the increasing influence of human beings. The change of the spatial pattern of ecological landscape in Fukang focused on the acreage alteration of plantation and badlands in pluvial fan and alluvial plain. The key factor was the dynamic variation of water-salt in water and soil resource utilization. Terrain and land utilization were the key factors affecting water table, and the continuous changes of the water table worked on the spatial distribution of soil water-salt. PMID:15506098

  3. Effects of wetland vs. landscape variables on parasite communities of Rana pipiens: links to anthropogenic factors

    USGS Publications Warehouse

    Schotthoefer, Anna M.; Rohr, Jason R.; Cole, Rebecca A.; Koehler, Anson V.; Johnson, Catherine M.; Johnson, Lucinda B.; Beasley, Val R.

    2011-01-01

    The emergence of several diseases affecting amphibian populations worldwide has prompted investigations into determinants of the occurrence and abundance of parasites in frogs. To understand the spatial scales and identify specific environmental factors that determine risks of parasitism in frogs, helminth communities in metamorphic frogs of the northern leopard frog (Rana pipiens) were examined in relation to wetland and landscape factors at local (1 km) and regional (10 km) spatial extents in an agricultural region of Minnesota (USA) using regression analyses, ordination, and variance partitioning techniques. Greater amounts of forested and woody wetland habitats, shorter distances between woody wetlands, and smaller-sized open water patches in surrounding landscapes were the most consistently positive correlates with the abundances, richness, and diversity of helminths found in the frogs. Wetland and local landscape variables were suggested as most important for larval trematode abundances, whereas local and regional landscape variables appeared most important for adult helminths. As previously reported, the sum concentration of atrazine and its metabolite desethylatrazine, was the strongest predictor of larval trematode communities. In this report, we highlight the additional influences of landscape factors. In particular, our data suggest that anthropogenic activities that have resulted in the loss of the availability and connectivity of suitable habitats in the surrounding landscapes of wetlands are associated with declines in helminth richness and abundance, but that alteration of wetland water quality through eutrophication or pesticide contamination may facilitate the transmission of certain parasite taxa when they are present at wetlands. Although additional research is needed to quantify the negative effects of parasitism on frog populations, efforts to reduce inputs of agrochemicals into wetlands to limit larval trematode infections may be warranted

  4. Effects of wetland vs. landscape variables on parasite communities of Rana pipiens: links to anthropogenic factors.

    PubMed

    Schotthoefer, Anna M; Rohr, Jason R; Cole, Rebecca A; Koehler, Anson V; Johnson, Catherine M; Johnson, Lucinda B; Beasley, Val R

    2011-06-01

    The emergence of several diseases affecting amphibian populations worldwide has prompted investigations into determinants of the occurrence and abundance of parasites in frogs. To understand the spatial scales and identify specific environmental factors that determine risks of parasitism in frogs, helminth communities in metamorphic frogs of the northern leopard frog (Rana pipiens) were examined in relation to wetland and landscape factors at local (1 km) and regional (10 km) spatial extents in an agricultural region of Minnesota (USA) using regression analyses, ordination, and variance partitioning techniques. Greater amounts of forested and woody wetland habitats, shorter distances between woody wetlands, and smaller-sized open water patches in surrounding landscapes were the most consistently positive correlates with the abundances, richness, and diversity of helminths found in the frogs. Wetland and local landscape variables were suggested as most important for larval trematode abundances, whereas local and regional landscape variables appeared most important for adult helminths. As previously reported, the sum concentration of atrazine and its metabolite desethylatrazine, was the strongest predictor of larval trematode communities. In this report, we highlight the additional influences of landscape factors. In particular, our data suggest that anthropogenic activities that have resulted in the loss of the availability and connectivity of suitable habitats in the surrounding landscapes of wetlands are associated with declines in helminth richness and abundance, but that alteration of wetland water quality through eutrophication or pesticide contamination may facilitate the transmission of certain parasite taxa when they are present at wetlands. Although additional research is needed to quantify the negative effects of parasitism on frog populations, efforts to reduce inputs of agrochemicals into wetlands to limit larval trematode infections may be warranted

  5. LANDSCAPE INFLUENCES ON LAKE CHEMISTRY OF SMALL DIMICTIC LAKES IN THE HUMAN DOMINATED SOUTHERN WISCONSIN LANDSCAPE

    EPA Science Inventory

    Changes in landscape heterogeneity, historic landcover change, and human disturbance regimes are governed by complex interrelated landscape processes that modify lake water quality through the addition of nutrients, sediment, anthropogenic chemicals, and changes in major ion conc...

  6. A significant nexus: Geographically isolated wetlands influence landscape hydrology

    NASA Astrophysics Data System (ADS)

    McLaughlin, Daniel L.; Kaplan, David A.; Cohen, Matthew J.

    2014-09-01

    Recent U.S. Supreme Court rulings have limited federal protections for geographically isolated wetlands (GIWs) except where a "significant nexus" to a navigable water body is demonstrated. Geographic isolation does not imply GIWs are hydrologically disconnected; indeed, wetland-groundwater interactions may yield important controls on regional hydrology. Differences in specific yield (Sy) between uplands and inundated GIWs drive differences in water level responses to precipitation and evapotranspiration, leading to frequent reversals in hydraulic gradients that cause GIWs to act as both groundwater sinks and sources. These reversals are predicted to buffer surficial aquifer dynamics and thus base flow delivery, a process we refer to as landscape hydrologic capacitance. To test this hypothesis, we connected models of soil moisture, upland water table, and wetland stage to simulate hydrology of a low-relief landscape with GIWs, and explored the influences of total wetland area, individual wetland size, climate, and soil texture on water table and base flow variation. Increasing total wetland area and decreasing individual wetland size substantially decreased water table and base flow variation (e.g., reducing base flow standard deviation by as much as 50%). GIWs also decreased the frequency of extremely high and low water tables and base flow deliveries. For the same total wetland area, landscapes with fewer (i.e., larger) wetlands exhibited markedly lower hydrologic capacitance than those with more (i.e., smaller) wetlands, highlighting the importance of small GIWs to regional hydrology. Our results suggest that GIWs buffer dynamics of the surficial aquifer and stream base flow, providing an indirect but significant nexus to the regional hydrologic system.

  7. Landscape influences on headwater streams on Fort Stewart, Georgia, USA

    SciTech Connect

    Jager, Yetta; Bevelhimer, Mark S; al., et.

    2011-01-01

    Military landscapes represent a mixture of undisturbed natural ecosystems, developed areas, and lands that support different types and intensities of military training. Research to understand water-quality influences of military landscapes usually involves intensive sampling in a few watersheds. In this study, we developed a survey design of accessible headwater watersheds intended to improve our ability to distinguish land water relationships in general, and training influences, in particular, on Fort Stewart, GA. We sampled and analyzed water from watershed outlets. We successfully developed correlative models for total suspended solids (TSS), total nitrogen (TN), organic carbon (OC), and organic nitrogen (ON), which dominated in this blackwater ecosystem. TSS tended to be greater in samples after rainfall and during the growing season, and models that included %Wetland suggested a build-and-flush relationship. We also detected a positive association between TSS and tank-training, which suggests a need to intercept sediment-laden runoff from training areas. Models for OC showed a negative association with %Grassland. TN and ON both showed negative associations with %Grassland, %Wetland, and %Forest. Unexpected positive associations were observed between OC and equipmenttraining activity and between ON and %Bare ground ? Roads. Future studies that combine our survey-based approach with more intensive monitoring of the timing and intensity of training would be needed to better understand the mechanisms for these empirical relationships involving military training. Looking beyond local effects on Fort Stewart streams, we explore questions about how exports of OC and nitrogen from coastal military installations ultimately influence estuaries downstream.

  8. Evaluating the influence of life-history characteristics on genetic structure: a comparison of small mammals inhabiting complex agricultural landscapes.

    PubMed

    Kierepka, Elizabeth M; Anderson, Sara J; Swihart, Robert K; Rhodes, Olin E

    2016-09-01

    Conversion of formerly continuous native habitats into highly fragmented landscapes can lead to numerous negative demographic and genetic impacts on native taxa that ultimately reduce population viability. In response to concerns over biodiversity loss, numerous investigators have proposed that traits such as body size and ecological specialization influence the sensitivity of species to habitat fragmentation. In this study, we examined how differences in body size and ecological specialization of two rodents (eastern chipmunk; Tamias striatus and white-footed mouse; Peromyscus leucopus) impact their genetic connectivity within the highly fragmented landscape of the Upper Wabash River Basin (UWB), Indiana, and evaluated whether landscape configuration and complexity influenced patterns of genetic structure similarly between these two species. The more specialized chipmunk exhibited dramatically more genetic structure across the UWB than white-footed mice, with genetic differentiation being correlated with geographic distance, configuration of intervening habitats, and complexity of forested habitats within sampling sites. In contrast, the generalist white-footed mouse resembled a panmictic population across the UWB, and no landscape factors were found to influence gene flow. Despite the extensive previous work in abundance and occupancy within the UWB, no landscape factor that influenced occupancy or abundance was correlated with genetic differentiation in either species. The difference in predictors of occupancy, abundance, and gene flow suggests that species-specific responses to fragmentation are scale dependent. PMID:27648250

  9. Introduction to landscape influences on stream habitats and biological assemblages

    EPA Science Inventory

    Viewing river systems within a landscape context is a relatively new and rapidly developing approach to river ecology. Although the linkages among landscapes and associated physicochemical and biological characteristics of rivers have long been recognized, the development of con...

  10. Influence of Landscape Structure and Human Modifications on Insect Biomass and Bat Foraging Activity in an Urban Landscape

    PubMed Central

    Threlfall, Caragh G.; Law, Bradley; Banks, Peter B.

    2012-01-01

    Urban landscapes are often located in biologically diverse, productive regions. As such, urbanization may have dramatic consequences for this diversity, largely due to changes in the structure and function of urban communities. We examined the influence of landscape productivity (indexed by geology), housing density and vegetation clearing on the spatial distribution of nocturnal insect biomass and the foraging activity of insectivorous bats in the urban landscape of Sydney, Australia. Nocturnal insect biomass (g) and bat foraging activity were sampled from 113 sites representing backyard, open space, bushland and riparian landscape elements, across urban, suburban and vegetated landscapes within 60 km of Sydney's Central Business District. We found that insect biomass was at least an order of magnitude greater within suburban landscapes in bushland and backyard elements located on the most fertile shale influenced geologies (both p<0.001) compared to nutrient poor sandstone landscapes. Similarly, the feeding activity of bats was greatest in bushland, and riparian elements within suburbs on fertile geologies (p = 0.039). Regression tree analysis indicated that the same three variables explained the major proportion of the variation in insect biomass and bat foraging activity. These were ambient temperature (positive), housing density (negative) and the percent of fertile shale geologies (positive) in the landscape; however variation in insect biomass did not directly explain bat foraging activity. We suggest that prey may be unavailable to bats in highly urbanized areas if these areas are avoided by many species, suggesting that reduced feeding activity may reflect under-use of urban habitats by bats. Restoration activities to improve ecological function and maintain the activity of a diversity of bat species should focus on maintaining and restoring bushland and riparian habitat, particularly in areas with fertile geology as these were key bat foraging

  11. Factors influencing wetland use by Canada geese

    USGS Publications Warehouse

    Naugle, D.E.; Gleason, J.S.; Jenks, J.A.; Higgins, K.F.; Mammenga, P.W.; Nusser, S.M.

    1997-01-01

    Seasonal and semi-permanent wetlands in eastern South Dakota were surveyed in 1995 and 1996 to identify habitat characteristics influencing wetland use by Canada geese (Branta canadensis maxima). Position of a wetland within the landscape and its area were important landscape-scale features influencing wetland use by geese. Our delineation of potential Canada goose habitat using a wetland geographic information system indicated that distribution and area of semi-permanent wetlands likely limit Canada goose occurrence in regions outside the Prairie Coteau. Periodicity in hydrologic cycles within landscapes also may influence goose use of wetlands in eastern South Dakota.

  12. LANDSCAPE INFLUENCES ON IN-STREAM BIOTIC INTEGRITY: USE OF MACROINVERTEBRATE METRICS TO IDENTIFY LANDSCAPE STRESSORS IN HEADWATER CATCHMENTS

    EPA Science Inventory

    The biotic integrity of streams is profoundly influenced by quantitative and qualitative features in the landscape of the surrounding catchment. In this study, aquatic macroinvertebrate metrics (e.g., relative abundance of Ephemeroptera, Trichoptera, and/or Plecoptera taxa, or t...

  13. Phonological Awareness: Factors of Influence

    ERIC Educational Resources Information Center

    Frohlich, Linda Paulina; Petermann, Franz; Metz, Dorothee

    2013-01-01

    Early child development is influenced by various genetic and environmental factors. This study aims to identify factors that affect the phonological awareness of preschool and first grade children. Based on a sample of 330 German-speaking children (mean age = 6.2 years) the following domains were evaluated: Parent factors, birth and pregnancy,…

  14. Influence of landscape composition and diversity on contaminant flux in terrestrial food webs: a case study of trace metal transfer to European blackbirds Turdus merula.

    PubMed

    Fritsch, Clémentine; Coeurdassier, Michaël; Faivre, Bruno; Baurand, Pierre-Emmanuel; Giraudoux, Patrick; van den Brink, Nico W; Scheifler, Renaud

    2012-08-15

    Although understanding the influence of the spatial arrangement of habitats and interacting communities on the processes of pollutant flux and impacts is critical for exposure and risk assessment, to date few studies have been devoted to this emergent topic. We tested the hypothesis that landscape composition and diversity affect the transfer of trace metals to vertebrates. Bioaccumulation of Cd and Pb in blood and feathers of European blackbirds Turdus merula (n=138) was studied over a smelter-impacted area (Northern France). Landscape composition (type and occurrence of the different habitats) and diversity (number of different habitat types and the proportional area distribution among habitat types) were computed around bird capture locations. Diet composition and contamination were assessed. No sex-related differences were detected, while age-related patterns were found: yearlings showed a sharper increase of tissue residues along the pollution gradient than older birds. Factors determining bird exposure acted at nested spatial scale. On a broad scale, environmental contamination mainly influenced metal levels in blackbirds, tissue residues increasing with soil contamination. At a finer grain, landscape composition and soil properties (pH, organic matter, clay) influenced metal transfer, while no influence of landscape diversity was detected. Landscape composition better explained metal transfer than soil properties did. Diet composition varied according to landscape composition, but diet diversity was not influenced by landscape diversity. Surprisingly, metal accumulation in some insect taxa was as high as in earthworms (known as hyper-accumulators). Results strongly suggested that variations in diet composition were the drivers through which landscape composition influenced metal transfer to blackbirds. This study shows that landscape features can affect pollutant transfer in food webs, partly through ecological processes related to spatial and foraging

  15. Influence of landscape composition and diversity on contaminant flux in terrestrial food webs: a case study of trace metal transfer to European blackbirds Turdus merula.

    PubMed

    Fritsch, Clémentine; Coeurdassier, Michaël; Faivre, Bruno; Baurand, Pierre-Emmanuel; Giraudoux, Patrick; van den Brink, Nico W; Scheifler, Renaud

    2012-08-15

    Although understanding the influence of the spatial arrangement of habitats and interacting communities on the processes of pollutant flux and impacts is critical for exposure and risk assessment, to date few studies have been devoted to this emergent topic. We tested the hypothesis that landscape composition and diversity affect the transfer of trace metals to vertebrates. Bioaccumulation of Cd and Pb in blood and feathers of European blackbirds Turdus merula (n=138) was studied over a smelter-impacted area (Northern France). Landscape composition (type and occurrence of the different habitats) and diversity (number of different habitat types and the proportional area distribution among habitat types) were computed around bird capture locations. Diet composition and contamination were assessed. No sex-related differences were detected, while age-related patterns were found: yearlings showed a sharper increase of tissue residues along the pollution gradient than older birds. Factors determining bird exposure acted at nested spatial scale. On a broad scale, environmental contamination mainly influenced metal levels in blackbirds, tissue residues increasing with soil contamination. At a finer grain, landscape composition and soil properties (pH, organic matter, clay) influenced metal transfer, while no influence of landscape diversity was detected. Landscape composition better explained metal transfer than soil properties did. Diet composition varied according to landscape composition, but diet diversity was not influenced by landscape diversity. Surprisingly, metal accumulation in some insect taxa was as high as in earthworms (known as hyper-accumulators). Results strongly suggested that variations in diet composition were the drivers through which landscape composition influenced metal transfer to blackbirds. This study shows that landscape features can affect pollutant transfer in food webs, partly through ecological processes related to spatial and foraging

  16. Landscape position influences microbial composition and function via redistribution of soil water across a watershed.

    PubMed

    Du, Zhe; Riveros-Iregui, Diego A; Jones, Ryan T; McDermott, Timothy R; Dore, John E; McGlynn, Brian L; Emanuel, Ryan E; Li, Xu

    2015-12-01

    Subalpine forest ecosystems influence global carbon cycling. However, little is known about the compositions of their soil microbial communities and how these may vary with soil environmental conditions. The goal of this study was to characterize the soil microbial communities in a subalpine forest watershed in central Montana (Stringer Creek Watershed within the Tenderfoot Creek Experimental Forest) and to investigate their relationships with environmental conditions and soil carbonaceous gases. As assessed by tagged Illumina sequencing of the 16S rRNA gene, community composition and structure differed significantly among three landscape positions: high upland zones (HUZ), low upland zones (LUZ), and riparian zones (RZ). Soil depth effects on phylogenetic diversity and β-diversity varied across landscape positions, being more evident in RZ than in HUZ. Mantel tests revealed significant correlations between microbial community assembly patterns and the soil environmental factors tested (water content, temperature, oxygen, and pH) and soil carbonaceous gases (carbon dioxide concentration and efflux and methane concentration). With one exception, methanogens were detected only in RZ soils. In contrast, methanotrophs were detected in all three landscape positions. Type I methanotrophs dominated RZ soils, while type II methanotrophs dominated LUZ and HUZ soils. The relative abundances of methanotroph populations correlated positively with soil water content (R = 0.72, P < 0.001) and negatively with soil oxygen (R = -0.53, P = 0.008). Our results suggest the coherence of soil microbial communities within and differences in communities between landscape positions in a subalpine forested watershed that reflect historical and contemporary environmental conditions. PMID:26431971

  17. Landscape Position Influences Microbial Composition and Function via Redistribution of Soil Water across a Watershed

    PubMed Central

    Du, Zhe; Riveros-Iregui, Diego A.; Jones, Ryan T.; McDermott, Timothy R.; Dore, John E.; McGlynn, Brian L.; Emanuel, Ryan E.

    2015-01-01

    Subalpine forest ecosystems influence global carbon cycling. However, little is known about the compositions of their soil microbial communities and how these may vary with soil environmental conditions. The goal of this study was to characterize the soil microbial communities in a subalpine forest watershed in central Montana (Stringer Creek Watershed within the Tenderfoot Creek Experimental Forest) and to investigate their relationships with environmental conditions and soil carbonaceous gases. As assessed by tagged Illumina sequencing of the 16S rRNA gene, community composition and structure differed significantly among three landscape positions: high upland zones (HUZ), low upland zones (LUZ), and riparian zones (RZ). Soil depth effects on phylogenetic diversity and β-diversity varied across landscape positions, being more evident in RZ than in HUZ. Mantel tests revealed significant correlations between microbial community assembly patterns and the soil environmental factors tested (water content, temperature, oxygen, and pH) and soil carbonaceous gases (carbon dioxide concentration and efflux and methane concentration). With one exception, methanogens were detected only in RZ soils. In contrast, methanotrophs were detected in all three landscape positions. Type I methanotrophs dominated RZ soils, while type II methanotrophs dominated LUZ and HUZ soils. The relative abundances of methanotroph populations correlated positively with soil water content (R = 0.72, P < 0.001) and negatively with soil oxygen (R = −0.53, P = 0.008). Our results suggest the coherence of soil microbial communities within and differences in communities between landscape positions in a subalpine forested watershed that reflect historical and contemporary environmental conditions. PMID:26431971

  18. Factors That Influence Teacher Attrition.

    ERIC Educational Resources Information Center

    Gonzalez, Patricia

    1995-01-01

    External, employment, and personal factors which influence teacher decisions to stay, leave, or transfer from teaching assignments are discussed, with emphasis on special education teachers. Factors attributed to teacher attrition in urban and rural environments also are briefly reviewed, along with attrition of related services professionals.…

  19. Influence of the Houma Navigation Canal on Salinity Patterns and Landscape Configuration in Coastal Louisiana

    USGS Publications Warehouse

    Steyer, Gregory D.; Sasser, Charles; Evers, Elaine; Swenson, Erick; Suir, Glenn; Sapkota, Sijan

    2008-01-01

    Coastal Louisiana is a dynamic and ever changing landscape. From 1956 to 2004, over 297,000 ha of Louisiana's coastal wetlands were lost because of the effects of natural and human-induced activities. Studies show that, in 2005, Hurricanes Katrina and Rita transformed over 56,200 ha of wetlands to open water in various parts of coastal Louisiana. Besides the catastrophic hurricanes, factors such as subsidence, sea-level rise, freshwater and sediment deprivation, saltwater intrusion, the dredging of oil and gas canals, navigation canals, shoreline erosion, and herbivory are all contributors to wetland loss in Louisiana. Various scientific literatures have well described the direct impacts associated with an immediate physical conversion of habitat in coastal Louisiana; however, the indirect impacts that are subtle and operate over longer time horizons (such as salinity intrusion) have been difficult to discern. In this report, long-term influences on salinity patterns and landscape configuration are evaluated for pre- and postconstruction periods of the Houma Navigation Canal (HNC), which is located in the coastal region of southeastern Louisiana. Analysis of daily and hourly salinity data from long-term data collection stations within the areas surrounding the HNC indicated that there were no obvious patterns in increasing salinity levels following the completion of the canal, except for the immediate increase in salinity spikes that occurred toward the completion of its construction in 1961. Increases in salinity spikes were also observed during a severe drought in 1999-2000. Data from Bayou Grand Caillou at Dulac, however, show a longer term trend of increasing salinity levels, which is similar to the pattern observed at the Houma Water Treatment Plant. A potential explanation for these patterns is based on the dredging history of the HNC, where dates of maintenance dredging correspond fairly closely to the salinity peaks in Bayou Grand Caillou and the canal. It

  20. Salting the landscapes in Transbaikalia: natural and technogenic factors

    NASA Astrophysics Data System (ADS)

    Peryazeva, E. G.; Plyusnin, A. M.; Chinavlev, A. M.

    2010-05-01

    , sulphur, strontium, lithium, molybdenum, nickel, and vanadium are widely spread there. Geochemical habit of basalts largely determines chemical compositions of waters and mineral formations in hearths of salting. Unloading the fissure-vein waters that evacuate solute from the Jurassic-Cretaceous volcanogenic-sedimentary deposits greatly effects chemical composition in some hearths of salting. Irrigation systems in many intermountain depressions influence the salting hearth formation. The associated secondary salting occurs as spots in the areas, where ground water surface reaches foot of loams during irrigation. Salting the landscapes takes out big areas of fertile lands from agricultural use, threatens with breakdowns at enterprises of thermal energetic that consume water as heat carrier.

  1. How Landscape Characteristics Influence Spatial Patterns of Transpiration

    NASA Astrophysics Data System (ADS)

    Hassler, S. K.; Weiler, M.; Zehe, E.; Blume, T.

    2015-12-01

    Quantifying transpiration in landscapes remains a challenging task. Especially bridging the gap between tree- or plot-scale measurements and information on the landscape scale which could be gathered from remote sensing, digital elevation models or forest inventories still poses considerable problems. These problems reach from errors associated with the measurements to the reliability of representing transpiration amounts by large-scale data. In this study we analyse spatial patterns of sap velocity to identify the importance of tree- or site-specific characteristics for transpiration at the landscape scale. We set up multiple linear regression models for a dataset of daily sap velocities for 61 trees at 24 locations in mixed beech and oak forests in a catchment in Luxemburg, recorded during the growing season of 2014. As predictors we use the tree-specific characteristics species, diameter and height and the site-specific characteristics basal area and number of stems for the respective stands as well as landscape attributes such as aspect, slope position and geology. Analysing the importance of these predictors could be useful for upscaling tree-based measurements to the landscape-scale based on data from digital elevation models, forest inventories or remote sensing. We also assess the temporal dynamics of the importance of tree- vs. site-specific predictors and link them to typical controls for sap flow such as atmospheric demand and soil moisture. First results indicate that site-specific predictors contribute considerably to the explained variance of the linear models. However, remotely sensed information explained very little of the variation in daily sap velocity patterns. Further analyses will quantify to which extent we can use the landscape-scale information from digital elevation models, geology and forest inventories to upscale tree-based transpiration estimates.

  2. Habitat selection in a rocky landscape: experimentally decoupling the influence of retreat site attributes from that of landscape features.

    PubMed

    Croak, Benjamin M; Pike, David A; Webb, Jonathan K; Shine, Richard

    2012-01-01

    Organisms selecting retreat sites may evaluate not only the quality of the specific shelter, but also the proximity of that site to resources in the surrounding area. Distinguishing between habitat selection at these two spatial scales is complicated by co-variation among microhabitat factors (i.e., the attributes of individual retreat sites often correlate with their proximity to landscape features). Disentangling this co-variation may facilitate the restoration or conservation of threatened systems. To experimentally examine the role of landscape attributes in determining retreat-site quality for saxicolous ectotherms, we deployed 198 identical artificial rocks in open (sun-exposed) sites on sandstone outcrops in southeastern Australia, and recorded faunal usage of those retreat sites over the next 29 months. Several landscape-scale attributes were associated with occupancy of experimental rocks, but different features were important for different species. For example, endangered broad-headed snakes (Hoplocephalus bungaroides) preferred retreat sites close to cliff edges, flat rock spiders (Hemicloea major) preferred small outcrops, and velvet geckos (Oedura lesueurii) preferred rocks close to the cliff edge with higher-than-average sun exposure. Standardized retreat sites can provide robust experimental data on the effects of landscape-scale attributes on retreat site selection, revealing interspecific divergences among sympatric taxa that use similar habitats.

  3. Habitat Selection in a Rocky Landscape: Experimentally Decoupling the Influence of Retreat Site Attributes from That of Landscape Features

    PubMed Central

    Croak, Benjamin M.; Pike, David A.; Webb, Jonathan K.; Shine, Richard

    2012-01-01

    Organisms selecting retreat sites may evaluate not only the quality of the specific shelter, but also the proximity of that site to resources in the surrounding area. Distinguishing between habitat selection at these two spatial scales is complicated by co-variation among microhabitat factors (i.e., the attributes of individual retreat sites often correlate with their proximity to landscape features). Disentangling this co-variation may facilitate the restoration or conservation of threatened systems. To experimentally examine the role of landscape attributes in determining retreat-site quality for saxicolous ectotherms, we deployed 198 identical artificial rocks in open (sun-exposed) sites on sandstone outcrops in southeastern Australia, and recorded faunal usage of those retreat sites over the next 29 months. Several landscape-scale attributes were associated with occupancy of experimental rocks, but different features were important for different species. For example, endangered broad-headed snakes (Hoplocephalus bungaroides) preferred retreat sites close to cliff edges, flat rock spiders (Hemicloea major) preferred small outcrops, and velvet geckos (Oedura lesueurii) preferred rocks close to the cliff edge with higher-than-average sun exposure. Standardized retreat sites can provide robust experimental data on the effects of landscape-scale attributes on retreat site selection, revealing interspecific divergences among sympatric taxa that use similar habitats. PMID:22701592

  4. Associations of grassland birds with landscape factors in southern Wisconsin

    USGS Publications Warehouse

    Ribic, C.A.; Sample, D.W.

    2001-01-01

    We investigated the association of grassland birds with field- and landscape-level habitat variables in south-central Wisconsin during 1985-1987. Landscape-level variables were measured and digitized at 200, 400 and 800 m from the perimeter of 38 200 m ?? 100 m strip transects. A mixture of field and landscape variables was associated with the density of savannah sparrow (Passerculus sandwichensis) and grasshopper sparrow (Ammodramus savannarum). Only landscape variables were associated with the density of bobolink (Dolichonyx oryzivorus), eastern meadowlark (Sturnella magna) and all birds that were grassland species of management concern. Field size was not an important predictor of bird density. Cover-type diversity of the surrounding area was commonly selected in the models for three species and all birds that were grassland species of management concern. Higher bird densities in the transects were associated with landscapes where the cover types were less diverse. Landscapes with low cover type diversity were dominated by grassland, pasture and hay. Field habitat, mean patch size of cover types and distance to woody vegetation were the next most common predictors of avian density. The density of some grassland birds increased as nonlinear woody features such as woodlots and shrub carrs decreased in patch size, decreased in total amount in the landscape and increased in distance from a transect. However, density of other species was positively associated with linear woody features such as the total amount and nearness of hedgerows. The composition of the surrounding landscape, at least out to 800 m, is important in grassland bird management.

  5. A SAM oligomerization domain shapes the genomic binding landscape of the LEAFY transcription factor.

    PubMed

    Sayou, Camille; Nanao, Max H; Jamin, Marc; Posé, David; Thévenon, Emmanuel; Grégoire, Laura; Tichtinsky, Gabrielle; Denay, Grégoire; Ott, Felix; Peirats Llobet, Marta; Schmid, Markus; Dumas, Renaud; Parcy, François

    2016-04-21

    Deciphering the mechanisms directing transcription factors (TFs) to specific genome regions is essential to understand and predict transcriptional regulation. TFs recognize short DNA motifs primarily through their DNA-binding domain. Some TFs also possess an oligomerization domain suspected to potentiate DNA binding but for which the genome-wide influence remains poorly understood. Here we focus on the LEAFY transcription factor, a master regulator of flower development in angiosperms. We have determined the crystal structure of its conserved amino-terminal domain, revealing an unanticipated Sterile Alpha Motif oligomerization domain. We show that this domain is essential to LEAFY floral function. Moreover, combined biochemical and genome-wide assays suggest that oligomerization is required for LEAFY to access regions with low-affinity binding sites or closed chromatin. This finding shows that domains that do not directly contact DNA can nevertheless have a profound impact on the DNA binding landscape of a TF.

  6. A SAM oligomerization domain shapes the genomic binding landscape of the LEAFY transcription factor

    PubMed Central

    Sayou, Camille; Nanao, Max H.; Jamin, Marc; Posé, David; Thévenon, Emmanuel; Grégoire, Laura; Tichtinsky, Gabrielle; Denay, Grégoire; Ott, Felix; Peirats Llobet, Marta; Schmid, Markus; Dumas, Renaud; Parcy, François

    2016-01-01

    Deciphering the mechanisms directing transcription factors (TFs) to specific genome regions is essential to understand and predict transcriptional regulation. TFs recognize short DNA motifs primarily through their DNA-binding domain. Some TFs also possess an oligomerization domain suspected to potentiate DNA binding but for which the genome-wide influence remains poorly understood. Here we focus on the LEAFY transcription factor, a master regulator of flower development in angiosperms. We have determined the crystal structure of its conserved amino-terminal domain, revealing an unanticipated Sterile Alpha Motif oligomerization domain. We show that this domain is essential to LEAFY floral function. Moreover, combined biochemical and genome-wide assays suggest that oligomerization is required for LEAFY to access regions with low-affinity binding sites or closed chromatin. This finding shows that domains that do not directly contact DNA can nevertheless have a profound impact on the DNA binding landscape of a TF. PMID:27097556

  7. Factors Influencing College Science Success

    ERIC Educational Resources Information Center

    Tai, Robert H.; Sadler, Philip M.; Mintzes, Joel J.

    2006-01-01

    In this paper, the authors report some of the salient findings of a large-scale, four-year national study, conducted at the Harvard-Smithsonian Center for Astrophysics, entitled "Factors Influencing College Science Success" (FICSS), which surveyed college students who enrolled in first-year biology, chemistry, and physics courses throughout the…

  8. Soft Factors Influence College Enrollment

    ERIC Educational Resources Information Center

    Fogg, Neeta P.; Harrington, Paul E.

    2010-01-01

    Evidence about the role that "soft factors" like student engagement and school environment play in influencing whether high school students go on to enroll in college is hard to come by. Over the past two years, the Center for Labor Market Studies (CLMS) of Northeastern University, with support from the Nellie Mae Education Foundation and the…

  9. Landscape characteristics influence morphological and genetic differentiation in a widespread raptor (Buteo jamaicensis).

    PubMed

    Hull, Joshua M; Hull, Angus C; Sacks, Benjamin N; Smith, Jeff P; Ernest, Holly B

    2008-02-01

    Landscape-scale population genetic structure in vagile vertebrates was commonly considered to be a contradiction in terms whereas recent studies have demonstrated behaviour and habitat associated structure in several such species. We investigate whether landscape features influence morphological and genetic differentiation in a widespread, mobile raptor. To accurately describe genetic differentiation associated with regional landscape factors, we first investigated subspecies relationships at a continental scale. We used 17 microsatellite loci and five morphological measurements to investigate differentiation between eastern and western subspecies of red-tailed hawks (Buteo jamaicensis) and to identify patterns between differentiation and habitat within western North America. Bayesian and frequency-based analyses of microsatellite data revealed clear distinctions between B. j. borealis (eastern) and B. j. calurus (western) samples. Furthermore, hawks sampled in Texas were stouter than those collected from the Rocky Mountains and farther west. Among western samples, birds from the Great Basin, Rocky Mountains, and Washington were significantly different in morphology than those from Oregon and California. We identified a pattern of isolation by distance among western breeding sites around the Sierra Nevada. Given the long-range dispersal capabilities of raptors, this pattern suggests that population-specific habitat preferences, corresponding with habitat breaks between eastern and western slopes of the Sierra Nevada, and/or regionally variable population densities limit migration between the Mediterranean habitat of central California and the xeric habitats of southern California and interior west. We suggest habitat preferences and regionally disparate population densities may play a role in shaping genetic structure in vagile avian taxa.

  10. Landscape characteristics influence morphological and genetic differentiation in a widespread raptor (Buteo jamaicensis).

    PubMed

    Hull, Joshua M; Hull, Angus C; Sacks, Benjamin N; Smith, Jeff P; Ernest, Holly B

    2008-02-01

    Landscape-scale population genetic structure in vagile vertebrates was commonly considered to be a contradiction in terms whereas recent studies have demonstrated behaviour and habitat associated structure in several such species. We investigate whether landscape features influence morphological and genetic differentiation in a widespread, mobile raptor. To accurately describe genetic differentiation associated with regional landscape factors, we first investigated subspecies relationships at a continental scale. We used 17 microsatellite loci and five morphological measurements to investigate differentiation between eastern and western subspecies of red-tailed hawks (Buteo jamaicensis) and to identify patterns between differentiation and habitat within western North America. Bayesian and frequency-based analyses of microsatellite data revealed clear distinctions between B. j. borealis (eastern) and B. j. calurus (western) samples. Furthermore, hawks sampled in Texas were stouter than those collected from the Rocky Mountains and farther west. Among western samples, birds from the Great Basin, Rocky Mountains, and Washington were significantly different in morphology than those from Oregon and California. We identified a pattern of isolation by distance among western breeding sites around the Sierra Nevada. Given the long-range dispersal capabilities of raptors, this pattern suggests that population-specific habitat preferences, corresponding with habitat breaks between eastern and western slopes of the Sierra Nevada, and/or regionally variable population densities limit migration between the Mediterranean habitat of central California and the xeric habitats of southern California and interior west. We suggest habitat preferences and regionally disparate population densities may play a role in shaping genetic structure in vagile avian taxa. PMID:18208488

  11. Influence of landscape elements on population densities and habitat use of three small-mammal species.

    SciTech Connect

    Mabry, Karen, E.; Dreelin, Erin, A.; Barrett, Gary, W.

    2003-01-01

    Mabry, K.E., E.A. Dreelin, and G.W. Barrett. 2003. Influence of landscape elements on population densities and habitat use of three small-mammal species. J. Mammology. 84(1):20-25. Corridor effects on population densities and habitat use of 3 small mammal species were assessed in an experimentally fragmented landscape. Corridor presence did not have a statistically significant effect on population densities of cotton rats or cotton mice; however, a significant effect was observed for old-field mice. The results suggest that landscape fragmentation and habitat structure may have varying effects on population densities of different species.

  12. Landscape characteristics influence pond occupancy by frogs after accounting for detectability

    USGS Publications Warehouse

    Mazerolle, M.J.; Desrochers, A.; Rochefort, L.

    2005-01-01

    Many investigators have hypothesized that landscape attributes such as the amount and proximity of habitat are important for amphibian spatial patterns. This has produced a number of studies focusing on the effects of landscape characteristics on amphibian patterns of occurrence in patches or ponds, most of which conclude that the landscape is important. We identified two concerns associated with these studies: one deals with their applicability to other landscape types, as most have been conducted in agricultural landscapes; the other highlights the need to account for the probability of detection. We tested the hypothesis that landscape characteristics influence spatial patterns of amphibian occurrence at ponds after accounting for the probability of detection in little-studied peatland landscapes undergoing peat mining. We also illustrated the costs of not accounting for the probability of detection by comparing our results to conventional logistic regression analyses. Results indicate that frog occurrence increased with the percent cover of ponds within 100, 250, and 1000 m, as well as the amount of forest cover within 1000 m. However, forest cover at 250 m had a negative influence on frog presence at ponds. Not accounting for the probability of detection resulted in underestimating the influence of most variables on frog occurrence, whereas a few were overestimated. Regardless, we show that conventional logistic regression can lead to different conclusions than analyses accounting for detectability. Our study is consistent with the hypothesis that landscape characteristics are important in determining the spatial patterns of frog occurrence at ponds. We strongly recommend estimating the probability of detection in field surveys, as this will increase the quality and conservation potential of models derived from such data. ?? 2005 by the Ecological Society of America.

  13. Factors influencing pacing in triathlon

    PubMed Central

    Wu, Sam SX; Peiffer, Jeremiah J; Brisswalter, Jeanick; Nosaka, Kazunori; Abbiss, Chris R

    2014-01-01

    Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon. PMID:25258562

  14. Factors influencing pacing in triathlon.

    PubMed

    Wu, Sam Sx; Peiffer, Jeremiah J; Brisswalter, Jeanick; Nosaka, Kazunori; Abbiss, Chris R

    2014-01-01

    Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon.

  15. Factors Influencing Curricular Reform; An Irish Perspective

    ERIC Educational Resources Information Center

    Ferris, Helena; Joyce, Pauline

    2015-01-01

    There are various influences and obstacles when planning an educational curriculum. The imprint of globalisation on the landscape of Irish medicine highlights the importance of delivering a diverse curriculum with international dimensions so that knowledge and skills can transfer across borders. It is also clear that medical emigration has a…

  16. Influence of landscape characteristics on retention of expandable radiocollars on young ungulates

    USGS Publications Warehouse

    Grovenburg, Troy W.; Klaver, Robert W.; Jacques, Christopher N.; Brinkman, Todd J.; Swanson, Christopher C.; DePerno, Christopher S.; Monteith, Kevin L.; Sievers, Jaret D.; Bleich, Vernon C.; Kie, John G.; Jenks, Jonathan A.

    2014-01-01

    One tool used for wildlife management is the deployment of radiocollars to gain knowledge of animal populations. Understanding the influence of individual factors (e.g., species, collar characteristics) and landscape characteristics (e.g., forested cover, shrubs, and fencing) on retention of expandable radiocollars for ungulates is important for obtaining empirical data on factors influencing ecology of young-of-the-year ungulates. During 2001–2009, we captured and radiocollared 198 white-tailed deer (Odocoileus virginianus) fawns, 142 pronghorn (Antilocapra americana) fawns, and 73 mule deer (O. hemionus) fawns in South Dakota, Minnesota, and California, USA. We documented 72 (36.4%), 8 (5.6%), and 7 (9.6%) premature (2, SE = 0.1, n = 75) compared with areas where fawns shed collars (x = 3.24 km/km2, SE = 0.1, n = 56) prior to 270 days. Researchers of fawns should consider that radiocollars can be shed prematurely when estimating desired sample size to yield a suitable strength of inference about some natural process of interest.

  17. Multi-taxa integrated landscape genetics for zoonotic infectious diseases: deciphering variables influencing disease emergence.

    PubMed

    Leo, Sarah S T; Gonzalez, Andrew; Millien, Virginie

    2016-05-01

    Zoonotic disease transmission systems involve sets of species interacting with each other and their environment. This complexity impedes development of disease monitoring and control programs that require reliable identification of spatial and biotic variables and mechanisms facilitating disease emergence. To overcome this difficulty, we propose a framework that simultaneously examines all species involved in disease emergence by integrating concepts and methods from population genetics, landscape ecology, and spatial statistics. Multi-taxa integrated landscape genetics (MTILG) can reveal how interspecific interactions and landscape variables influence disease emergence patterns. We test the potential of our MTILG-based framework by modelling the emergence of a disease system across multiple species dispersal, interspecific interaction, and landscape scenarios. Our simulations showed that both interspecific-dependent dispersal patterns and landscape characteristics significantly influenced disease spread. Using our framework, we were able to detect statistically similar inter-population genetic differences and highly correlated spatial genetic patterns that imply species-dependent dispersal. Additionally, species that were assigned coupled-dispersal patterns were affected to the same degree by similar landscape variables. This study underlines the importance of an integrated approach to investigating emergence of disease systems. MTILG is a robust approach for such studies and can identify potential avenues for targeted disease management strategies.

  18. Factors influencing healthcare service quality

    PubMed Central

    Mosadeghrad, Ali Mohammad

    2014-01-01

    Background: The main purpose of this study was to identify factors that influence healthcare quality in the Iranian context. Methods: Exploratory in-depth individual and focus group interviews were conducted with 222 healthcare stakeholders including healthcare providers, managers, policy-makers, and payers to identify factors affecting the quality of healthcare services provided in Iranian healthcare organisations. Results: Quality in healthcare is a production of cooperation between the patient and the healthcare provider in a supportive environment. Personal factors of the provider and the patient, and factors pertaining to the healthcare organisation, healthcare system, and the broader environment affect healthcare service quality. Healthcare quality can be improved by supportive visionary leadership, proper planning, education and training, availability of resources, effective management of resources, employees and processes, and collaboration and cooperation among providers. Conclusion: This article contributes to healthcare theory and practice by developing a conceptual framework that provides policy-makers and managers a practical understanding of factors that affect healthcare service quality. PMID:25114946

  19. Landscape-scale variation in an anthropogenic factor shapes immune gene variation within a wild population.

    PubMed

    Gonzalez-Quevedo, Catalina; Davies, Richard G; Phillips, Karl P; Spurgin, Lewis G; Richardson, David S

    2016-09-01

    Understanding the spatial scale at which selection acts upon adaptive genetic variation in natural populations is fundamental to our understanding of evolutionary ecology, and has important ramifications for conservation. The environmental factors to which individuals of a population are exposed can vary at fine spatial scales, potentially generating localized patterns of adaptation. Here, we compared patterns of neutral and major histocompatibility complex (MHC) variation within an island population of Berthelot's pipit (Anthus berthelotii) to assess whether landscape-level differences in pathogen-mediated selection generate fine-scale spatial structuring in these immune genes. Specifically, we tested for spatial associations between the distribution of avian malaria, and the factors previously shown to influence that distribution, and MHC variation within resident individuals. Although we found no overall genetic structure across the population for either neutral or MHC loci, we did find localized associations between environmental factors and MHC variation. One MHC class I allele (ANBE48) was directly associated with malaria infection risk, while the presence of the ANBE48 and ANBE38 alleles within individuals correlated (positively and negatively, respectively) with distance to the nearest poultry farm, an anthropogenic factor previously shown to be an important determinant of disease distribution in the study population. Our findings highlight the importance of considering small spatial scales when studying the patterns and processes involved in evolution at adaptive loci. PMID:27411090

  20. Landscape-scale variation in an anthropogenic factor shapes immune gene variation within a wild population.

    PubMed

    Gonzalez-Quevedo, Catalina; Davies, Richard G; Phillips, Karl P; Spurgin, Lewis G; Richardson, David S

    2016-09-01

    Understanding the spatial scale at which selection acts upon adaptive genetic variation in natural populations is fundamental to our understanding of evolutionary ecology, and has important ramifications for conservation. The environmental factors to which individuals of a population are exposed can vary at fine spatial scales, potentially generating localized patterns of adaptation. Here, we compared patterns of neutral and major histocompatibility complex (MHC) variation within an island population of Berthelot's pipit (Anthus berthelotii) to assess whether landscape-level differences in pathogen-mediated selection generate fine-scale spatial structuring in these immune genes. Specifically, we tested for spatial associations between the distribution of avian malaria, and the factors previously shown to influence that distribution, and MHC variation within resident individuals. Although we found no overall genetic structure across the population for either neutral or MHC loci, we did find localized associations between environmental factors and MHC variation. One MHC class I allele (ANBE48) was directly associated with malaria infection risk, while the presence of the ANBE48 and ANBE38 alleles within individuals correlated (positively and negatively, respectively) with distance to the nearest poultry farm, an anthropogenic factor previously shown to be an important determinant of disease distribution in the study population. Our findings highlight the importance of considering small spatial scales when studying the patterns and processes involved in evolution at adaptive loci.

  1. Factors Influencing Return to Work

    PubMed Central

    Brewerton, D. A.; Daniel, J. W.

    1971-01-01

    Seventy-seven patients with severe brachial plexus injuries were interviewed two or more years later to determine their success in returning to work and the factors that had led to good or bad resettlement. For most of them these were crucial issues potentially influencing the rest of their lives. When interviewed virtually all had regular jobs in open industry, but many had endured long delays and most were working entirely one-handed. Failure of communication was regrettably common. Too often advice by doctors had been lacking, and there was evidence that the services for vocational resettlement could be improved. PMID:5123911

  2. Tests of landscape influence: nest predation and brood parasitism in fragmented ecosystems.

    PubMed

    Tewksbury, Joshua J; Garner, Lindy; Garner, Shannon; Lloyd, John D; Saab, Victoria; Martin, Thomas E

    2006-03-01

    increased appreciation of the multiple scales at which landscape components influence predator and parasite behavior.

  3. Tests of landscape influence: Nest predation and brood parasitism in fragmented ecosystems

    USGS Publications Warehouse

    Tewksbury, J.J.; Garner, L.; Garner, S.; Lloyd, J.D.; Saab, V.; Martin, T.E.

    2006-01-01

    increased appreciation of the multiple scales at which landscape components influence predator and parasite behavior. ?? 2006 by the Ecological Society of America.

  4. Biomechanical factors contributing to self-organization in seagrass landscapes

    USGS Publications Warehouse

    Fonseca, M.S.; Koehl, M.A.R.; Kopp, B.S.

    2007-01-01

    Field observations have revealed that when water flow is consistently from one direction, seagrass shoots align in rows perpendicular to the primary axis of flow direction. In this study, live Zostera marina shoots were arranged either randomly or in rows perpendicular to the flow direction and tested in a seawater flume under unidirectional flow and waves to determine if shoot arrangement: a) influenced flow-induced force on individual shoots, b) differentially altered water flow through the canopy, and c) influenced light interception by the canopy. In addition, blade breaking strength was compared with flow-induced force to determine if changes in shoot arrangement might reduce the potential for damage to shoots. Under unidirectional flow, both current velocity in the canopy and force on shoots were significantly decreased when shoots were arranged in rows as compared to randomly. However, force on shoots was nearly constant with downstream distance, arising from the trade-off of shoot bending and in-canopy flow reduction. The coefficient of drag was higher for randomly-arranged shoots at low velocities (< 30 cm s- 1) but converged rapidly among the two shoot arrangements at higher velocities. Shoots arranged in rows tended to intercept slightly more light than those arranged randomly. Effects of shoot arrangement under waves were less clear, potentially because we did not achieve the proper plant size?row spacing ratio. At this point, we may only suggest that water motion, as opposed to light capture, is the dominant physical mechanism responsible for these shoot arrangements. Following a computation of the Environmental Stress Factor, we concluded that even photosynthetically active blades may be damaged or broken under frequently encountered storm conditions, irrespective of shoot arrangement. We hypothesize that when flow is generally from one direction, seagrass bed patterns over multiple scales of consideration may arise as a cumulative effect of

  5. Does fire influence the landscape-scale distribution of an invasive mesopredator?

    PubMed

    Payne, Catherine J; Ritchie, Euan G; Kelly, Luke T; Nimmo, Dale G

    2014-01-01

    Predation and fire shape the structure and function of ecosystems globally. However, studies exploring interactions between these two processes are rare, especially at large spatial scales. This knowledge gap is significant not only for ecological theory, but also in an applied context, because it limits the ability of landscape managers to predict the outcomes of manipulating fire and predators. We examined the influence of fire on the occurrence of an introduced and widespread mesopredator, the red fox (Vulpes vulpes), in semi-arid Australia. We used two extensive and complimentary datasets collected at two spatial scales. At the landscape-scale, we surveyed red foxes using sand-plots within 28 study landscapes - which incorporated variation in the diversity and proportional extent of fire-age classes - located across a 104 000 km2 study area. At the site-scale, we surveyed red foxes using camera traps at 108 sites stratified along a century-long post-fire chronosequence (0-105 years) within a 6630 km2 study area. Red foxes were widespread both at the landscape and site-scale. Fire did not influence fox distribution at either spatial scale, nor did other environmental variables that we measured. Our results show that red foxes exploit a broad range of environmental conditions within semi-arid Australia. The presence of red foxes throughout much of the landscape is likely to have significant implications for native fauna, particularly in recently burnt habitats where reduced cover may increase prey species' predation risk. PMID:25291186

  6. Nitrogen dynamics among cropland and riparian buffers: soil-landscape influences.

    PubMed

    Young, Eric O; Briggs, Russell D

    2007-01-01

    Nitrate (NO3-) leaching to ground water poses water quality concerns in some settings. Riparian buffers have been advocated to reduce excess ground water NO3- concentrations. We characterized inorganic N in soil solution and shallow ground water for 16 paired cropland-riparian plots from 2003 to 2005. The sites were located at two private dairy farms in Central New York on silt and gravelly silt loam soils (Aeric Endoaqualfs, Fluvaquentic Endoaquepts, Fluvaquentic Eutrudepts, Glossaquic Hapludalfs, and Glossic Hapludalfs). It was hypothesized that cropland N inputs and soil-landscape variability would jointly affect NO3- leaching and transformations in ground water. Results showed that well and moderately well drained fields had consistently higher ground water NO3- compared to more imperfectly drained fields receiving comparable N inputs. Average 50-cm depth soil solution NO3- and ground water dissolved oxygen (DO) explained 64% of average cropland ground water NO3- variability. Cropland ground water with an average DO of <3 mg L(-1) tended to have <4 mg L(-1) of NO3- with a water table depth (WTD) of landscape factors strongly influenced NO3- behavior and suggest the importance of accurately characterizing soil variability along cropland-riparian zones.

  7. Influence of landscape features on the microgeographic genetic structure of a resident songbird.

    PubMed

    Adams, R V; Lazerte, S E; Otter, K A; Burg, T M

    2016-08-01

    Landscape features influence individual dispersal and as a result can affect both gene flow and genetic variation within and between populations. The landscape of British Columbia, Canada, is already highly heterogeneous because of natural ecological and geological transitions, but disturbance from human-mediated processes has further fragmented continuous habitat, particularly in the central plateau region. In this study, we evaluated the effects of landscape heterogeneity on the genetic structure of a common resident songbird, the black-capped chickadee (Poecile atricapillus). Previous work revealed significant population structuring in British Columbia that could not be explained by physical barriers, so our aim was to assess the pattern of genetic structure at a microgeographic scale and determine the effect of different landscape features on genetic differentiation. A total of 399 individuals from 15 populations were genotyped for fourteen microsatellite loci revealing significant population structuring in this species. Individual- and population-based analyses revealed as many as nine genetic clusters with isolation in the north, the central plateau and the south. Moreover, a mixed modelling approach that accounted for non-independence of pairwise distance values revealed a significant effect of land cover and elevation resistance on genetic differentiation. These results suggest that barriers in the landscape influence dispersal which has led to the unexpectedly high levels of population isolation. Our study demonstrates the importance of incorporating landscape features when interpreting patterns of population differentiation. Despite taking a microgeographic approach, our results have opened up additional questions concerning the processes influencing dispersal and gene flow at the local scale.

  8. Influence of landscape features on the microgeographic genetic structure of a resident songbird.

    PubMed

    Adams, R V; Lazerte, S E; Otter, K A; Burg, T M

    2016-08-01

    Landscape features influence individual dispersal and as a result can affect both gene flow and genetic variation within and between populations. The landscape of British Columbia, Canada, is already highly heterogeneous because of natural ecological and geological transitions, but disturbance from human-mediated processes has further fragmented continuous habitat, particularly in the central plateau region. In this study, we evaluated the effects of landscape heterogeneity on the genetic structure of a common resident songbird, the black-capped chickadee (Poecile atricapillus). Previous work revealed significant population structuring in British Columbia that could not be explained by physical barriers, so our aim was to assess the pattern of genetic structure at a microgeographic scale and determine the effect of different landscape features on genetic differentiation. A total of 399 individuals from 15 populations were genotyped for fourteen microsatellite loci revealing significant population structuring in this species. Individual- and population-based analyses revealed as many as nine genetic clusters with isolation in the north, the central plateau and the south. Moreover, a mixed modelling approach that accounted for non-independence of pairwise distance values revealed a significant effect of land cover and elevation resistance on genetic differentiation. These results suggest that barriers in the landscape influence dispersal which has led to the unexpectedly high levels of population isolation. Our study demonstrates the importance of incorporating landscape features when interpreting patterns of population differentiation. Despite taking a microgeographic approach, our results have opened up additional questions concerning the processes influencing dispersal and gene flow at the local scale. PMID:26905462

  9. Inbreeding avoidance, patch isolation and matrix permeability influence dispersal and settlement choices by male agile antechinus in a fragmented landscape.

    PubMed

    Banks, Sam C; Lindenmayer, David B

    2014-03-01

    Animal dispersal is highly non-random and has important implications for the dynamics of populations in fragmented habitat. We identified interpatch dispersal events from genetic tagging, parentage analyses and assignment tests and modelled the factors associated with apparent emigration and post-dispersal settlement choices by individual male agile antechinus (Antechinus agilis, a marsupial carnivore of south-east Australian forests). Emigration decisions were best modelled with on data patch isolation and inbreeding risk. The choice of dispersal destination by males was influenced by inbreeding risk, female abundance, patch size, patch quality and matrix permeability (variation in land cover). Males were less likely to settle in patches without highly unrelated females. Our findings highlight the importance of individual-level dispersal data for understanding how multiple processes drive non-randomness in dispersal in modified landscapes. Fragmented landscapes present novel environmental, demographic and genetic contexts in which dispersal decisions are made, so the major factors affecting dispersal decisions in fragmented habitat may differ considerably from unfragmented landscapes. We show that the spatial scale of genetic neighbourhoods can be large in fragmented habitat, such that dispersing males can potentially settle in the presence of genetically similar females after moving considerable distances, thereby necessitating both a choice to emigrate and a choice of where to settle to avoid inbreeding.

  10. Soil physical properties: Key factors for successful reclamation of disturbed landscapes

    NASA Astrophysics Data System (ADS)

    Krümmelbein, Julia; Raab, Thomas

    2013-04-01

    The practice of open cast mining, e.g. for lignite, results in major landscape disturbances and especially affects soils because relocation and subsequent mixing of naturally developed soil horizons leads to areas with extremely altered soil properties compared to the undisturbed conditions. Various reclamation measures are applied to recover the reconstructed landscape for different land use options. Major parts of the post mining landscapes are used for agriculture, agroforestry or silviculture, the remaining voids of the coal mines fill successively with groundwater after mine closure and are or will be used mainly for touristic and leisure purposes. Small proportions of the post mining areas are left for natural succession, or habitats for endangered flora and fauna are initiated. In reclamation research, many studies have focused on soil chemical and biological constraints of post mining substrates and investigated factors such as unsuitable pH, in many cases very low pH, (poor) nutrient contents and (poor) biological activity. But the initial and developing soil physical parameters and functions are also key factors for the success of reclamation practices. The soil water and gas balance influence strongly the suitability of a site for the intended future land use. The mechanical stability of the soil determines the rigidity of the pore system against deforming forces and thereby the persistence of soil functions, such as water and air permeability over time. The amendment of unfavourable (initial) soil physical properties is in most cases more complex and time-consuming than e.g. optimization of pH or fertilization with nutrients. Moreover, regarding the suitability of a site e.g. as a habitat for plants or microorganisms, poor physical pre-conditions can turn substrates with perfect nutrient contents and composition and pH into infertile locations of very low productivity. We show results of an on-going field study where the effects of different

  11. Factors influencing the acceptance of nature conservation measures--a qualitative study in Switzerland.

    PubMed

    Schenk, Anita; Hunziker, Marcel; Kienast, Felix

    2007-04-01

    Landscapes fulfil a multitude of ecological and social functions. Due to the fact that both traditional and everyday landscapes today face many different threats, regulatory measures have been undertaken in many countries to protect and further sustainable landscape development. They include legislation as well as economic incentives. In recent years, however, it has become clear that just to have a few laws and to spend money on subsidies is not enough. Factors other than legislation are also essential to further the sustainable development of landscapes. One of the basic factors affecting the success or failure of landscape conservation measures is public acceptance of these measures. Our project took this as its starting point. The objective was to determine which conditions and factors influence acceptance positively or negatively. To this end 22 Swiss who are directly affected by nature conservation measures, in particular by mire landscape and dry meadow conservation measures, were interviewed using qualitative interview techniques. It is shown that perception, communication, and possibilities to participate are the most decisive driving factors influencing the formation of a long-lasting acceptance. Furthermore, acceptance may be based mainly on economic criteria, on usefulness, on ecological or even aesthetic aspects. It can be shown that not all of these motivations lead to a long-lasting acceptance. Ecologically based acceptance seems the most promising because it is founded on general convictions. Economic incentives--though important--seem to generate only superficial acceptance and do not seem to be as important as is usually assumed.

  12. Time factor in soils of Georgia-mirror or memory of landscapes?

    PubMed

    Matchavariani, Lia

    2012-04-01

    The geographic pattern of soils in mountainous region of Georgia is presented. Time is considered as one of the most important factors of soil formation in mountain areas. The age of soil cover in the areas above 1000-1200 m a.s.l. is less than 10,000-12,000 yr b.p. These soils are considered as young component of landscape. In the landscapes below this level soils do not correspond to modern ecological conditions. We can confirm that in Georgia higher than 1000-1200 m asl soils correspond to ecological conditions and they are mirror of landscapes, as one of the most important postulates of soil science. In other case, we can talk about soils memory-distorted mirror of landscapes. For diagnosing of relic features (pedogenic and lithogenic) in soils of Georgia the micromorphological method is used. The majority of landscapes in Georgia are heavily used for agriculture and suffer from high instability. These landscapes are very fragile today, characterized by high soil erosion and strong pollution with heavy metalsand radionuclides.

  13. Local and Landscape Factors Determining Occurrence of Phyllostomid Bats in Tropical Secondary Forests

    PubMed Central

    Avila-Cabadilla, Luis Daniel; Sanchez-Azofeifa, Gerardo Arturo; Stoner, Kathryn Elizabeth; Alvarez-Añorve, Mariana Yolotl; Quesada, Mauricio; Portillo-Quintero, Carlos Alonso

    2012-01-01

    Neotropical forests are being increasingly replaced by a mosaic of patches of different successional stages, agricultural fields and pasture lands. Consequently, the identification of factors shaping the performance of taxa in anthropogenic landscapes is gaining importance, especially for taxa playing critical roles in ecosystem functioning. As phyllostomid bats provide important ecological services through seed dispersal, pollination and control of animal populations, in this study we assessed the relationships between phyllostomid occurrence and the variation in local and landscape level habitat attributes caused by disturbance. We mist-netted phyllostomids in 12 sites representing 4 successional stages of a tropical dry forest (initial, early, intermediate and late). We also quantitatively characterized the habitat attributes at the local (vegetation structure complexity) and the landscape level (forest cover, area and diversity of patches). Two focal scales were considered for landscape characterization: 500 and 1000 m. During 142 sampling nights, we captured 606 individuals representing 15 species and 4 broad guilds. Variation in phyllostomid assemblages, ensembles and populations was associated with variation in local and landscape habitat attributes, and this association was scale-dependent. Specifically, we found a marked guild-specific response, where the abundance of nectarivores tended to be negatively associated with the mean area of dry forest patches, while the abundance of frugivores was positively associated with the percentage of riparian forest. These results are explained by the prevalence of chiropterophilic species in the dry forest and of chiropterochorous species in the riparian forest. Our results indicate that different vegetation classes, as well as a multi-spatial scale approach must be considered for evaluating bat response to variation in landscape attributes. Moreover, for the long-term conservation of phyllostomids in anthropogenic

  14. Landscape influences on genetic differentiation among bull trout populations in a stream-lake network

    USGS Publications Warehouse

    Meeuwig, M.H.; Guy, C.S.; Kalinowski, S.T.; Fredenberg, W.A.

    2010-01-01

    This study examined the influence of landscape heterogeneity on genetic differentiation between migratory bull trout (Salvelinus confluentus) populations in Glacier National Park, Montana. An information-theoretic approach was used to compare different conceptual models of dispersal associated with barriers, different models of isolation by distance, and the combined effects of barriers, waterway distance, patch size, and intra- and inter-drainage distribution of populations on genetic differentiation between bull trout populations. The effect of distance between populations on genetic differentiation was best explained by partitioning the effects of mainstem and tributary stream sections. Models that categorized barriers as having a one-way effect (i.e. allowed downstream dispersal) or a two-way effect were best supported. Additionally, patch size and the distribution of populations among drainages influenced genetic differentiation. Genetic differentiation between bull trout populations in Glacier National Park is linked to landscape features that restrict dispersal. However, this analysis illustrates that modelling variability within landscape features, such as dispersal corridors, will benefit landscape genetic analyses. Additionally, the framework used for evaluating the effects of barriers must consider not just barrier presence, but also potential asymmetries in barrier effects with respect to the organism under investigation.

  15. Factors influencing boar sperm cryosurvival.

    PubMed

    Roca, J; Hernández, M; Carvajal, G; Vázquez, J M; Martínez, E A

    2006-10-01

    Optimal sperm cryopreservation is a prerequisite for the sustainable commercial application of frozen-thawed boar semen for AI. Three experiments were performed to identify factors influencing variability of postthaw sperm survival among 464 boar ejaculates. Sperm-rich ejaculate fractions were cryopre-served using a standard freezing-thawing procedure for 0.5-mL plastic straws and computer-controlled freezing equipment. Postthaw sperm motility (assessed with a computer-assisted semen analysis system) and viability (simultaneously probed by flow cytometry analysis after triple-fluorescent stain), evaluated 30 and 150 min postthaw, were used to estimate the success of cryopreservation. In the first experiment, 168 unselected ejaculates (1 ejaculate/boar), from boars of 6 breeds with a wide age range (8 to 48 mo), were cryopreserved over a 12-mo period to evaluate the predictive value of boar (breed and age), semen collection, transport variables (season of ejaculate collection, interval between collections, and ejaculate temperature exposure), initial semen traits, and sperm quality before freezing on sperm survival after freezing-thawing. In Exp. 2, 4 ejaculates from each of 29 boars, preselected according to their initial semen traits and sperm quality before freezing, were collected and frozen over a 6-mo period to evaluate the influence of interboar and intraboar ejaculate variability in the survival of sperm after cryopreservation. In Exp. 3, 12 ejaculates preselected as for Exp. 2, from each of 15 boars with known good sperm cryosurvival, were collected and frozen over a 12-mo period to estimate the sustainability of sperm cryosurvival between ejaculates over time. Boar and semen collection and transport variables were not predictive of sperm cryosurvival among ejaculates. Initial semen traits and sperm quality variables observed before freezing explained 23.2 and 10.9%, respectively, of the variation in postthaw sperm motility and viability. However, more that

  16. Evidence for an intrinsic factor promoting landscape genetic divergence in Madagascan leaf-litter frogs

    PubMed Central

    Wollenberg Valero, Katharina C.

    2015-01-01

    The endemic Malagasy frog radiations are an ideal model system to study patterns and processes of speciation in amphibians. Large-scale diversity patterns of these frogs, together with other endemic animal radiations, led to the postulation of new and the application of known hypotheses of species diversification causing diversity patterns in this biodiversity hotspot. Both extrinsic and intrinsic factors have been studied in a comparative framework, with extrinsic factors usually being related to the physical environment (landscape, climate, river catchments, mountain chains), and intrinsic factors being clade-specific traits or constraints (reproduction, ecology, morphology, physiology). Despite some general patterns emerging from such large-scale comparative analyses, it became clear that the mechanism of diversification in Madagascar may vary among clades, and may be a multifactorial process. In this contribution, I test for intrinsic factors promoting population-level divergence within a clade of terrestrial, diurnal leaf-litter frogs (genus Gephyromantis) that has previously been shown to diversify according to extrinsic factors. Landscape genetic analyses of the microendemic species Gephyromantis enki and its widely distributed, larger sister species Gephyromantis boulengeri over a rugged landscape in the Ranomafana area shows that genetic variance of the smaller species cannot be explained by landscape resistance alone. Both topographic and riverine barriers are found to be important in generating this divergence. This case study yields additional evidence for the probable importance of body size in lineage diversification. PMID:26136766

  17. Using multitemporal Landsat imagery to monitor and model the influences of landscape pattern on urban expansion in a metropolitan region

    NASA Astrophysics Data System (ADS)

    Yang, Yetao; Wong, Louis Ngai Yuen; Chen, Chao; Chen, Tao

    2014-01-01

    Studying the interaction between landscape patterns and temporal land-use changes in a metropolitan area can improve understanding of the urbanization process. Multitemporal remote sensing imagery is widely used to map the urbanization-caused temporal land-use dynamics, which mainly appear as built-up growth. Remote sensing integrated with landscape metrics is also used to quantitatively describe the landscape pattern of the urban area in recent literature. However, few studies have focused on the interaction between the pattern and the process of urbanization in a metropolitan area. We propose a grid-based framework to analyze the influence of the landscape pattern on the built-up growth by using the multitemporal Landsat imagery. Remote sensing classification method is used to obtain thematic land-use maps. Built-up growth is then extracted from the multitemporal classification results by a postclassification change detection. Landscape pattern, which is quantitatively described by landscape metrics, is derived from the thematic land-use maps. A grid-based method is used to analyze the spatial variation of landscape pattern and its related built-up growth. Finally, the spatial relationship between the landscape pattern and the built-up growth characters is assessed and modeled by using the mathematical regression method. The present study shows that an apparent correlation between landscape pattern and built-up growth exists. The correlation reflects the inherent influences of landscape pattern on urban expansion. The landscape pattern indicates the land development stage, while the urbanization stage determines the speed and style of the following built-up growth. Scales, including temporal scale and spatial scale, are important to modeling the landscape pattern effects on the built-up growth. The proposed analysis framework is efficient in detecting and modeling the landscape pattern effects on the built-up growth.

  18. Does Fire Influence the Landscape-Scale Distribution of an Invasive Mesopredator?

    PubMed Central

    Payne, Catherine J.; Ritchie, Euan G.; Kelly, Luke T.; Nimmo, Dale G.

    2014-01-01

    Predation and fire shape the structure and function of ecosystems globally. However, studies exploring interactions between these two processes are rare, especially at large spatial scales. This knowledge gap is significant not only for ecological theory, but also in an applied context, because it limits the ability of landscape managers to predict the outcomes of manipulating fire and predators. We examined the influence of fire on the occurrence of an introduced and widespread mesopredator, the red fox (Vulpes vulpes), in semi-arid Australia. We used two extensive and complimentary datasets collected at two spatial scales. At the landscape-scale, we surveyed red foxes using sand-plots within 28 study landscapes – which incorporated variation in the diversity and proportional extent of fire-age classes – located across a 104 000 km2 study area. At the site-scale, we surveyed red foxes using camera traps at 108 sites stratified along a century-long post-fire chronosequence (0–105 years) within a 6630 km2 study area. Red foxes were widespread both at the landscape and site-scale. Fire did not influence fox distribution at either spatial scale, nor did other environmental variables that we measured. Our results show that red foxes exploit a broad range of environmental conditions within semi-arid Australia. The presence of red foxes throughout much of the landscape is likely to have significant implications for native fauna, particularly in recently burnt habitats where reduced cover may increase prey species’ predation risk. PMID:25291186

  19. Small beetle, large-scale drivers: how regional and landscape factors affect outbreaks of the European spruce bark beetle

    PubMed Central

    Seidl, Rupert; Müller, Jörg; Hothorn, Torsten; Bässler, Claus; Heurich, Marco; Kautz, Markus

    2016-01-01

    Summary 1. Unprecedented bark beetle outbreaks have been observed for a variety of forest ecosystems recently, and damage is expected to further intensify as a consequence of climate change. In Central Europe, the response of ecosystem management to increasing infestation risk has hitherto focused largely on the stand level, while the contingency of outbreak dynamics on large-scale drivers remains poorly understood. 2. To investigate how factors beyond the local scale contribute to the infestation risk from Ips typographus (Col., Scol.), we analysed drivers across seven orders of magnitude in scale (from 103 to 1010 m2) over a 23-year period, focusing on the Bavarian Forest National Park. Time-discrete hazard modelling was used to account for local factors and temporal dependencies. Subsequently, beta regression was applied to determine the influence of regional and landscape factors, the latter characterized by means of graph theory. 3. We found that in addition to stand variables, large-scale drivers also strongly influenced bark beetle infestation risk. Outbreak waves were closely related to landscape-scale connectedness of both host and beetle populations as well as to regional bark beetle infestation levels. Furthermore, regional summer drought was identified as an important trigger for infestation pulses. Large-scale synchrony and connectivity are thus key drivers of the recently observed bark beetle outbreak in the area. 4. Synthesis and applications. Our multiscale analysis provides evidence that the risk for biotic disturbances is highly dependent on drivers beyond the control of traditional stand-scale management. This finding highlights the importance of fostering the ability to cope with and recover from disturbance. It furthermore suggests that a stronger consideration of landscape and regional processes is needed to address changing disturbance regimes in ecosystem management. PMID:27041769

  20. The Influence of Vegetation and Landscape Structural Connectivity on Butterflies (Lepidoptera: Papilionoidea and Hesperiidae), Carabids (Coleoptera: Carabidae), Syrphids (Diptera: Syrphidae), and Sawflies (Hymenoptera: Symphyta) in Northern Italy Farmland.

    PubMed

    Burgio, Giovanni; Sommaggio, Daniele; Marini, Mario; Puppi, Giovanna; Chiarucci, Alessandro; Landi, Sara; Fabbri, Roberto; Pesarini, Fausto; Genghini, Marco; Ferrari, Roberto; Muzzi, Enrico; van Lenteren, Joop C; Masetti, Antonio

    2015-10-01

    Landscape structure as well as local vegetation influence biodiversity in agroecosystems. A study was performed to evaluate the effect of floristic diversity, vegetation patterns, and landscape structural connectivity on butterflies (Lepidoptera: Papilionoidea and Hesperiidae), carabids (Coleoptera: Carabidae), syrphids (Diptera: Syrphidae), and sawflies (Hymenoptera: Symphyta). Vegetation analysis and insect samplings were carried out in nine sites within an intensively farmed landscape in northern Italy. Plant species richness and the percentage of tree, shrub, and herb cover were determined by means of the phytosociological method of Braun-Blanquet. Landscape structural connectivity was measured as the total length of hedgerow network (LHN) in a radius of 500 m around the center of each sampling transect. Butterflies species richness and abundance were positively associated both to herb cover and to plant species richness, but responded negatively to tree and shrub cover. Shrub cover was strictly correlated to both species richness and activity density of carabids. The species richness of syrphids was positively influenced by herb cover and plant richness, whereas their abundance was dependent on ligneous vegetation and LHN. Rarefaction analysis revealed that sawfly sampling was not robust and no relationship could be drawn with either vegetation parameters or structural connectivity. The specific responses of each insect group to the environmental factors should be considered in order to refine and optimize landscape management interventions targeting specific conservation endpoints.

  1. Predicting uncertainty in sediment transport and landscape evolution - the influence of initial surface conditions

    NASA Astrophysics Data System (ADS)

    Hancock, G. R.; Coulthard, T. J.; Lowry, J. B. C.

    2016-05-01

    Numerical landscape evolution models were initially developed to examine natural catchment hydrology and geomorphology and have become a common tool to examine geomorphic behaviour over a range of time and space scales. These models all use a digital elevation model (DEM) as a representation of the landscape surface and a significant issue is the quality and resolution of this surface. Here we focus on how subtle perturbations or roughness on the DEM surface can produce alternative model results. This study is carried out by randomly varying the elevations of the DEM surface and examining the effect on sediment transport rates and geomorphology for a proposed rehabilitation design for a post-mining landscape using multiple landscape realisations with increasing magnitudes of random changes. We show that an increasing magnitude of random surface variability does not appear to have any significant effect on sediment transport over millennial time scales. However, the random surface variability greatly changes the temporal pattern or delivery of sediment output. A significant finding is that all simulations at the end of the 10,000 year modelled period are geomorphologically similar and present a geomorphological equifinality. However, the individual patterns of erosion and deposition were different for repeat simulations with a different sequence of random perturbations. The alternative positions of random perturbations strongly influence local patterns of hillslope erosion and evolution together with the pattern and behaviour of deposition. The findings demonstrate the complex feedbacks that occur even within a simple modelled system.

  2. Relative effects of climatic and local factors on fire occurrence in boreal forest landscapes of northeastern China.

    PubMed

    Wu, Zhiwei; He, Hong S; Yang, Jian; Liu, Zhihua; Liang, Yu

    2014-09-15

    Fire significantly affects species composition, structure, and ecosystem processes in boreal forests. Our study objective was to identify the relative effects of climate, vegetation, topography, and human activity on fire occurrence in Chinese boreal forest landscapes. We used historical fire ignition for 1966-2005 and the statistical method of Kernel Density Estimation to derive fire-occurrence density (number of fires/km(2)). The Random Forest models were used to quantify the relative effects of climate, vegetation, topography, and human activity on fire-occurrence density. Our results showed that fire-occurrence density tended to be spatially clustered. Human-caused fire occurrence was highly clustered at the southern part of the region, where human population density is high (comprising about 75% of the area's population). In the north-central areas where elevations are the highest in the region and less densely populated, lightning-caused fires were clustered. Climate factors (e.g., fine fuel and duff moisture content) were important at both regional and landscape scales. Human activity factors (e.g., distance to nearest settlement and road) were secondary to climate as the primary fire occurrence factors. Predictions of fire regimes often assume a strong linkage between climate and fire but usually with less emphasis placed on the effects of local factors such as human activity. We therefore suggest that accurate forecasting of fire regime should include human influences such as those measured by forest proximity to roads and human settlements. PMID:24960228

  3. Factors related to northern goshawk landscape use in the western Great Lakes region

    USGS Publications Warehouse

    Bruggeman, Jason E.; Andersen, David E.; Woodford, James E.

    2014-01-01

    Northern Goshawks (Accipiter gentilis) are a species of special conservation concern in the western Great Lakes bioregion and elsewhere in North America, and exhibit landscape-scale spatial use patterns. However, little information exists about Northern Goshawk habitat relations at broad spatial extents, as most existing published information comes from a few locations of relatively small spatial extent and, in some cases, short durations. We used an information-theoretic approach to evaluate competing hypotheses regarding factors (forest canopy cover, successional stage, and heights of the canopy top and base) related to odds of Northern Goshawk landscape use throughout the western Great Lakes bioregion based on an occupancy survey completed in 2008 (Bruggeman et al. 2011). We also combined these data with historical data of Northern Goshawk nest locations in the bioregion from 1979–2006 to evaluate the same competing hypotheses to elucidate long-term trends in use. The odds of Northern Goshawk use in 2008, and from 1979–2008, were positively correlated with average percent canopy cover. In the best-approximating models developed using 1979–2008 data, the odds of landscape use were positively correlated with the percentages of the landscape having canopy heights between 10 m and 25 m, and 25 m and 50 m, and the amount of variability in canopy base height. Also, the odds of landscape use were negatively correlated with the average height at the canopy base. Our results suggest multiple habitat factors were related to Northern Goshawk landscape-scale habitat use, similar to habitat use described at smaller spatial scales in the western Great Lakes bioregion and in western North America and Europe.

  4. Factors Influencing College Curriculum Choice

    ERIC Educational Resources Information Center

    Reynolds, Carl L.

    1977-01-01

    A recent study conducted at the University of Illinois on what influences college students to consider the agricultural education curriculum showed that the curriculum choice process is somewhat different for agricultural education majors than for students in the non-agricultural education group. Important influences include vocational agriculture…

  5. How does landscape use influence small mammal diversity, abundance and biomass in hedgerow networks of farming landscapes?

    NASA Astrophysics Data System (ADS)

    Michel, Nadia; Burel, Françoise; Butet, Alain

    2006-07-01

    Over the last decades, profound changes in agricultural practices in the world have led to modifications of land-use as well as landscape structure and composition. Major changes resulted in enlargement of parcel size, increase of cultivated areas and drastic reduction of permanent elements such as woods, hedges or natural meadows. In this context we chose to investigate the composition and structure of small mammal communities in the hedgerow networks of three landscape units of Western France (Brittany) differing by their level of agricultural land-use intensity and hedgerow network density: a slightly intensified dense hedgerow network landscape unit (BOC1), a moderately intensified and fragmented hedgerow network landscape unit (BOC2) and a highly intensified landscape unit on an area reclaimed from the sea (POL). Characterization of small mammal communities was performed using live trapping on permanent habitats (eight hedges per landscape unit). In each of the 24 trapping units, a standardized method was used consisting of a baited 100-m trap-line. Diversity indices were used to compare the three communities. Species richness didn't vary across landscapes whereas Shannon's index of diversity underlined a clear difference between, on the one hand, the most intensified landscape unit (POL) which displayed the lowest diversity and, on the other hand, the two other less intensified units. The abundance of small mammals differed between the three sites: they were significantly more numerous in the hedges of the most intensified site than in hedges of the two other sites. Differences between species also appeared: for example, the Bank vole ( Clethrionomys glareolus) was very characteristic of POL, whereas the Pygmy shrew ( Sorex minutus) was much more associated with BOC sites. Within hedges, like for abundance, small mammal biomass was the highest in the most intensified site (POL > BOC2 = BOC1). On the contrary, at the landscape scale, biomass was the lowest in

  6. Influences of Land Use on Greenhouse Gas Fluxes within Mixed Landscapes

    NASA Astrophysics Data System (ADS)

    Xiao, J.; Contosta, A.; Deng, J.; Lepine, L. C.; Li, C.; Ollinger, S. V.; Ouimette, A.; Tang, J.; Varner, R. K.

    2015-12-01

    Human activities (e.g., urbanization, land use planning) have led to complex patterns of urban, suburban, agricultural, and forested landscapes. Ecosystems within these landscapes play an important role in climate regulation by acting as regulators of CO2 and other greenhouse gases and altering surface albedo and other biophysical properties. The overarching goal of our work is to examine the interactions among carbon cycling, land use, and climate change in a human-dominated, mixed land use region that includes urban, suburban, agriculture, and forest land uses. We combine field measurements of carbon storage and greenhouse gas emissions (CO2, CH4, and N2O), an improved process-based biogeochemical model - DNDC (DeNitrification and DeComposition) designed to predict C fluxes and trace gas emissions, and historical and projected land use change data derived from Landsat imagery and cellular automata/agent-based modeling. Our specific objectives designed to achieve the overarching goal are to: (1) Measure C pools and greenhouse gas emissions (CO2, CH4, and N2O) in urban, suburban, agricultural, and forested landscapes; (2) Improve and parameterize the DNDC (DeNitrification and DeComposition) model and validate model predictions; (3) Develop historical land use change data for the last three decades from Landsat imagery and projections of future land use change; (4) Generate spatially continuous predictions of C pools and greenhouse gas emissions using Urban-DNDC and assess how land use interacts with C cycling and climate change and how future land use change will influence carbon sequestration potential within these complex landscapes. Our results will have implications for crafting effective land management policies that balance C sequestration and climate mitigation with food production, forest resources and many other services that these landscapes provide.

  7. Landscape alterations influence differential habitat use of nesting buteos and ravens within sagebrush ecosystem: implications for transmission line development

    USGS Publications Warehouse

    Coates, Peter S.; Howe, Kristy B.; Casazza, Michael L.; Delehanty, David J.

    2014-01-01

    A goal in avian ecology is to understand factors that influence differences in nesting habitat and distribution among species, especially within changing landscapes. Over the past 2 decades, humans have altered sagebrush ecosystems as a result of expansion in energy production and transmission. Our primary study objective was to identify differences in the use of landscape characteristics and natural and anthropogenic features by nesting Common Ravens (Corvus corax) and 3 species of buteo (Swainson's Hawk [Buteo swainsoni], Red-tailed Hawk [B. jamaicensis], and Ferruginous Hawk [B. regalis]) within a sagebrush ecosystem in southeastern Idaho. During 2007–2009, we measured multiple environmental factors associated with 212 nest sites using data collected remotely and in the field. We then developed multinomial models to predict nesting probabilities by each species and predictive response curves based on model-averaged estimates. We found differences among species related to nesting substrate (natural vs. anthropogenic), agriculture, native grassland, and edge (interface of 2 cover types). Most important, ravens had a higher probability of nesting on anthropogenic features (0.80) than the other 3 species (Artemisia spp.), favoring increased numbers of nesting ravens and fewer nesting Ferruginous Hawks. Our results indicate that habitat alterations, fragmentation, and forthcoming disturbances anticipated with continued energy development in sagebrush steppe ecosystems can lead to predictable changes in raptor and raven communities.

  8. Factors that Influence Participation in Online Learning

    ERIC Educational Resources Information Center

    Vonderwell, Selma; Zachariah, Sajit

    2005-01-01

    This study explored what factors influenced learner participation in two sections of a graduate online course at a Midwestern university. Findings indicated that online learner participation and patterns of participation are influenced by the following factors: technology and interface characteristics, content area experience, student roles and…

  9. Natural landscape and stream segment attributes influencing the distribution and relative abundance of riverine smallmouth bass in Missouri

    USGS Publications Warehouse

    Brewer, S.K.; Rabeni, C.F.; Sowa, S.P.; Annis, G.

    2007-01-01

    Protecting and restoring fish populations on a regional basis are most effective if the multiscale factors responsible for the relative quality of a fishery are known. We spatially linked Missouri's statewide historical fish collections to environmental features in a geographic information system, which was used as a basis for modeling the importance of landscape and stream segment features in supporting a population of smallmouth bass Micropterus dolomieu. Decision tree analyses were used to develop probability-based models to predict statewide occurrence and within-range relative abundances. We were able to identify the range of smallmouth bass throughout Missouri and the probability of occurrence within that range by using a few broad landscape variables: the percentage of coarse-textured soils in the watershed, watershed relief, and the percentage of soils with low permeability in the watershed. The within-range relative abundance model included both landscape and stream segment variables. As with the statewide probability of occurrence model, soil permeability was particularly significant. The predicted relative abundance of smallmouth bass in stream segments containing low percentages of permeable soils was further influenced by channel gradient, stream size, spring-flow volume, and local slope. Assessment of model accuracy with an independent data set showed good concordance. A conceptual framework involving naturally occurring factors that affect smallmouth bass potential is presented as a comparative model for assessing transferability to other geographic areas and for studying potential land use and biotic effects. We also identify the benefits, caveats, and data requirements necessary to improve predictions and promote ecological understanding. ?? Copyright by the American Fisheries Society 2007.

  10. Changes in species diversity of arboreal spiders in Mexican coffee agroecosystems: untangling the web of local and landscape influences driving diversity.

    PubMed

    Hajian-Forooshani, Zachary; Gonthier, David J; Marín, Linda; Iverson, Aaron L; Perfecto, Ivette

    2014-01-01

    Agricultural intensification is implicated as a major driver of global biodiversity loss. Local management and landscape scale factors both influence biodiversity in agricultural systems, but there are relatively few studies to date looking at how local and landscape scales influence biodiversity in tropical agroecosystems. Understanding what drives the diversity of groups of organisms such as spiders is important from a pragmatic point of view because of the important biocontrol services they offer to agriculture. Spiders in coffee are somewhat enigmatic because of their positive or lack of response to agricultural intensification. In this study, we provide the first analysis, to our knowledge, of the arboreal spiders in the shade trees of coffee plantations. In the Soconusco region of Chiapas, Mexico we sampled across 38 sites on 9 coffee plantations. Tree and canopy connectedness were found to positively influence overall arboreal spider richness and abundance. We found that different functional groups of spiders are responding to different local and landscape factors, but overall elevation was most important variable influencing arboreal spider diversity. Our study has practical management applications that suggest having shade grown coffee offers more suitable habitat for arboreal spiders due to a variety of the characteristics of the shade trees. Our results which show consistently more diverse arboreal spider communities in lower elevations are important in light of looming global climate change. As the range of suitable elevations for coffee cultivation shrinks promoting arboreal spider diversity will be important in sustaining the viability of coffee. PMID:25392751

  11. Changes in species diversity of arboreal spiders in Mexican coffee agroecosystems: untangling the web of local and landscape influences driving diversity.

    PubMed

    Hajian-Forooshani, Zachary; Gonthier, David J; Marín, Linda; Iverson, Aaron L; Perfecto, Ivette

    2014-01-01

    Agricultural intensification is implicated as a major driver of global biodiversity loss. Local management and landscape scale factors both influence biodiversity in agricultural systems, but there are relatively few studies to date looking at how local and landscape scales influence biodiversity in tropical agroecosystems. Understanding what drives the diversity of groups of organisms such as spiders is important from a pragmatic point of view because of the important biocontrol services they offer to agriculture. Spiders in coffee are somewhat enigmatic because of their positive or lack of response to agricultural intensification. In this study, we provide the first analysis, to our knowledge, of the arboreal spiders in the shade trees of coffee plantations. In the Soconusco region of Chiapas, Mexico we sampled across 38 sites on 9 coffee plantations. Tree and canopy connectedness were found to positively influence overall arboreal spider richness and abundance. We found that different functional groups of spiders are responding to different local and landscape factors, but overall elevation was most important variable influencing arboreal spider diversity. Our study has practical management applications that suggest having shade grown coffee offers more suitable habitat for arboreal spiders due to a variety of the characteristics of the shade trees. Our results which show consistently more diverse arboreal spider communities in lower elevations are important in light of looming global climate change. As the range of suitable elevations for coffee cultivation shrinks promoting arboreal spider diversity will be important in sustaining the viability of coffee.

  12. Factors influencing dust suppressant effectiveness

    SciTech Connect

    Copeland, C.R.; Eisele, T.C.; Chesney, D.J.; Kawatra, S.K.

    2008-11-15

    Water sprays are a common method used to reduce particulate matter (PM) emissions. Various factors such as wettability, surface area coverage, fine particle engulfment rates, interparticle adhesion forces, suppressant penetration and suppressant longevity have all been suggested as critical factors in achieving effective PM control. However, it has not been established which of these factors are the most important. Experimental work indicated that suppressant penetration is the most critical of these factors. The length of time after application that suppressants were effective was also improved by using hygroscopic reagents that retained moisture to prevent evaporation. Maximizing suppressant penetration and improving suppressant longevity led to an average 86% reduction in PM10 concentrations in laboratory dust tower tests.

  13. Genetic factors influencing alcohol dependence

    PubMed Central

    Mayfield, R D; Harris, R A; Schuckit, M A

    2008-01-01

    Plentiful data from both animal and human studies support the importance of genetic influences in substance abuse and dependence (Bierut et al., 1998; Tsuang et al., 1998; Kendler et al., 2003). This review summarizes the evidence supporting such genetic influences, places them into perspective regarding animal and human studies, discusses the importance of both genes and environment, and highlights some specific genes of interest regarding the vulnerabilities for problems associated with alcohol use disorders. A long history of repetitive heavy use of alcohol exists across generations as well as the high prevalence of alcohol-related problems in Western societies. Moreover, the information offered here addresses the importance of more general issues regarding genetics and gene expression related to alcohol abuse and dependence. PMID:18362899

  14. Influences of floral composition and environment on plant biomarkers across a Cretaceous landscape (Big Cedar Ridge)

    NASA Astrophysics Data System (ADS)

    Bush, R. T.; Diefendorf, A. F.; Wing, S. L.; McInerney, F. A.

    2013-12-01

    The Late Cretaceous fossil site at Big Cedar Ridge (BCR; late Campanian, 72.7 Ma), located in the Bighorn Basin, Wyoming, USA, contains a flora preserved in situ in a volcanic ash tuff over an organic-rich paleosol. The BCR flora is irregularly but extensively exposed along a ~4 km north-south transect and records a lowland flora that grew on a coastal delta on the western shore of the Cretaceous Interior Seaway (Meeteetse Formation). The transect spans a diverse landscape and a range of environmental gradients from very carbon-rich, swampy soils in the southern portion to less carbon-rich in the north; the landscape is also intersected by multiple inactive channel cuts that were filling with sediment and organic matter at the time of ash deposition. Recently Wing and others (2012, Ecological Monographs) described the composition of the local plant community at high resolution across the entire landscape, including identification and quantification of cover and richness for >122 taxonomic morphotypes, for each of 100 sites along the transect. Big Cedar Ridge captures an important time in the ecological development of plant communities: the site preserves ferns, gymnosperms, and angiosperms in 'fern thicket' floral assemblages, which are rare today, as well as disturbed habitats with abundant herbaceous 'dicot' angiosperms. During the Late Cretaceous angiosperms were globally increasing in abundance, displacing other plant groups as vegetational dominants. This setting allows for a novel analysis of plant biomarkers in the context of floral diversity, abundance, and landscape heterogeneity. We quantified leaf waxes (n-alkyl lipids), plant-derived terpenoids, bacterial hopanes, carbon isotope values (including bulk and compound-specific), and percent total organic carbon of the underlying paleosol for 36 sites along the transect in order to assess the influence of floral composition and soil environment on biomarker distributions and preservation. We compare lipid

  15. [Dynamics and influence width of dry valley landscape boundary in upper reaches of Minjiang River].

    PubMed

    Yang, Zhao-Ping; Chang, Yu; Yang, Meng; Hu, Yuan-Man; Bu, Ren-Cang; He, Xing-Yuan

    2007-09-01

    Based on RS and GIS techniques, the distribution extent of the dry valley in upper reaches of Minjiang River was determined, with the dynamics and influence width of its landscape boundary analyzed. The results indicated that the dry valley had a gradually expanded distribution, and the total length of its boundary was increased. The boundary complexity increased from 1974 to 1995 but decreased from 1995 to 2000, and the upper boundary of the dry valley ascended rapidly along mountain slope. The uppermost elevation of the dry valley boundary was 3128 m in 1974, 3167 m in 1995, and 3181 m in 2000. In the last 26 years, the upper boundary of the dry valley ascended 53 m in total, being about 2 m per year. The influence width of the dry valley boundary was 800 m, which could be regarded as a buffer zone to disturbances. The area between 800-1200 m from the dry valley boundary to exterior was a transition zone intensely influenced by the dry valley and its surrounding landscape, which should be addressed in the restoration of the dry valley. PMID:18062298

  16. Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow

    NASA Astrophysics Data System (ADS)

    Kurylyk, Barret L.; Hayashi, Masaki; Quinton, William L.; McKenzie, Jeffrey M.; Voss, Clifford I.

    2016-02-01

    Recent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near-surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau-wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near-surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three-dimensional model of subsurface water flow and coupled energy transport with freeze-thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.

  17. Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow

    USGS Publications Warehouse

    Kurylyk, Barret; Masaki, Masaki; Quinton, William L.; McKenzie, Jeffrey M.; Voss, Clifford I.

    2016-01-01

    Recent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near-surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau-wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near-surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three-dimensional model of subsurface water flow and coupled energy transport with freeze-thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.

  18. The Environmental Factors Influencing Attrition.

    ERIC Educational Resources Information Center

    Villella, Edward F.

    1986-01-01

    Offers an economics/business-management perspective on student attrition, focusing on the external macro-environment (including such factors as government funding of education, changing enrollment patterns, and the increased number of postsecondary institutions) and the internal micro-environment (exhibiting characteristics of intangibility,…

  19. Climate and landscape influence on indicators of lake carbon cycling through spatial patterns in dissolved organic carbon.

    PubMed

    Lapierre, Jean-Francois; Seekell, David A; Del Giorgio, Paul A

    2015-12-01

    Freshwater ecosystems are strongly influenced by both climate and the surrounding landscape, yet the specific pathways connecting climatic and landscape drivers to the functioning of lake ecosystems are poorly understood. Here, we hypothesize that the links that exist between spatial patterns in climate and landscape properties and the spatial variation in lake carbon (C) cycling at regional scales are at least partly mediated by the movement of terrestrial dissolved organic carbon (DOC) in the aquatic component of the landscape. We assembled a set of indicators of lake C cycling (bacterial respiration and production, chlorophyll a, production to respiration ratio, and partial pressure of CO2 ), DOC concentration and composition, and landscape and climate characteristics for 239 temperate and boreal lakes spanning large environmental and geographic gradients across seven regions. There were various degrees of spatial structure in climate and landscape features that were coherent with the regionally structured patterns observed in lake DOC and indicators of C cycling. These different regions aligned well, albeit nonlinearly along a mean annual temperature gradient; whereas there was a considerable statistical effect of climate and landscape properties on lake C cycling, the direct effect was small and the overall effect was almost entirely overlapping with that of DOC concentration and composition. Our results suggest that key climatic and landscape signals are conveyed to lakes in part via the movement of terrestrial DOC to lakes and that DOC acts both as a driver of lake C cycling and as a proxy for other external signals.

  20. Climate and landscape influence on indicators of lake carbon cycling through spatial patterns in dissolved organic carbon.

    PubMed

    Lapierre, Jean-Francois; Seekell, David A; Del Giorgio, Paul A

    2015-12-01

    Freshwater ecosystems are strongly influenced by both climate and the surrounding landscape, yet the specific pathways connecting climatic and landscape drivers to the functioning of lake ecosystems are poorly understood. Here, we hypothesize that the links that exist between spatial patterns in climate and landscape properties and the spatial variation in lake carbon (C) cycling at regional scales are at least partly mediated by the movement of terrestrial dissolved organic carbon (DOC) in the aquatic component of the landscape. We assembled a set of indicators of lake C cycling (bacterial respiration and production, chlorophyll a, production to respiration ratio, and partial pressure of CO2 ), DOC concentration and composition, and landscape and climate characteristics for 239 temperate and boreal lakes spanning large environmental and geographic gradients across seven regions. There were various degrees of spatial structure in climate and landscape features that were coherent with the regionally structured patterns observed in lake DOC and indicators of C cycling. These different regions aligned well, albeit nonlinearly along a mean annual temperature gradient; whereas there was a considerable statistical effect of climate and landscape properties on lake C cycling, the direct effect was small and the overall effect was almost entirely overlapping with that of DOC concentration and composition. Our results suggest that key climatic and landscape signals are conveyed to lakes in part via the movement of terrestrial DOC to lakes and that DOC acts both as a driver of lake C cycling and as a proxy for other external signals. PMID:26150108

  1. Landscape context mediates influence of local food abundance on wetland use by wintering shorebirds in an agricultural valley

    USGS Publications Warehouse

    Taft, Oriane W.; Haig, Susan M.

    2006-01-01

    While it is widely understood that local abundance of benthic invertebrates can greatly influence the distribution and abundance of wetland birds, no studies have examined if wetland landscape context can mediate this relationship. We studied the influence of wetland food abundance and landscape context on use of agricultural wetlands by wintering dunlin (Calidris alpina) and killdeer (Charadrius vociferus) in the Willamette Valley of Oregon, USA, over two winters (1999a??2000, 2000a??2001) of differing rainfall and subsequent habitat distribution. We monitored bird use (frequency of occurrence and abundance) at a sample of wetlands differing in local food abundance (density and biomass) and landscape context [adjacent shorebird habitat (defined as ha of wet habitat with less than 50% vegetative cover and within a 2-km radius) and nearest neighbor distance]. We evaluated predictive models for bird use using linear regression and the Cp criterion to select the most parsimonious model. During the dry winter (2000a??2001), dunlin exhibited greater use of sites with higher invertebrate density and biomass but also with more adjacent shorebird habitat and closest to a wetland neighbor. However, neither landscape context nor food abundance were important predictors of dunlin use during the wet winter (1999a??2000). Use of sites by killdeer was unrelated to either local food abundance or landscape context measures during both winters. Our findings contribute to a growing recognition of the importance of landscape structure to wetland birds and highlight a number of implications for the spatial planning and enhancement of wetlands using a landscape approach.

  2. Factors that Influence Adolescents to Smoke.

    ERIC Educational Resources Information Center

    Smith, Karen H.; Stutts, Mary Ann

    1999-01-01

    A survey of the factors that influence adolescents (n=246) to smoke found that family smoking behavior, peer pressure, and prior beliefs were more important in predicting smoking level than were advertising and antismoking information. (Author/JOW)

  3. Factors influencing alginate gel biocompatibility.

    PubMed

    Tam, Susan K; Dusseault, Julie; Bilodeau, Stéphanie; Langlois, Geneviève; Hallé, Jean-Pierre; Yahia, L'Hocine

    2011-07-01

    Alginate remains the most popular polymer used for cell encapsulation, yet its biocompatibility is inconsistent. Two commercially available alginates were compared, one with 71% guluronate (HiG), and the other with 44% (IntG). Both alginates were purified, and their purities were verified. After 2 days in the peritoneal cavity of C57BL/6J mice, barium (Ba)-gel and calcium (Ca)-gel beads of IntG alginate were clean, while host cells were adhered to beads of HiG alginate. IntG gel beads, however, showed fragmentation in vivo while HiG gel beads stayed firm. The physicochemical properties of the sodium alginates and their gels were thoroughly characterized. The intrinsic viscosity of IntG alginate was 2.5-fold higher than that of HiG alginate, suggesting a greater molecular mass. X-ray photoelectron spectroscopy indicated that both alginates were similar in elemental composition, including low levels of counterions in all gels. The wettabilities of the alginates and gels were also identical, as measured by contact angles of water on dry films. Ba-gel beads of HiG alginate resisted swelling and degradation when immersed in water, much more than the other gel beads. These results suggest that the main factors contributing to the biocompatibility of gels of purified alginate are the mannuronate/guluronate content and/or intrinsic viscosity.

  4. Parent Involvement: Influencing Factors and Implications.

    ERIC Educational Resources Information Center

    Pena, Delores C.

    2000-01-01

    Investigated the involvement of Mexican American parents in their children's elementary schools. Interviews with teachers, parents, and administrators and observations of parent activities indicated that parent involvement was influenced by factors like language, parent cliques, parent education, school staff attitudes, cultural factors, and…

  5. What Factors Influence Wind Perceptions

    NASA Astrophysics Data System (ADS)

    Stein, Tatiana

    Over the last decade, wind power has emerged as a possible source of energy and has attracted the attention of homeowners and policy makers worldwide. Many technological hurdles have been overcome in the last few years that make this technology feasible and economical. The United States has added more wind power than any other type of electric generation in 2012. Depending on the location, wind resources have shown to have the potential to offer 20% of the nation's electricity; a single, large wind turbine has the capacity to produce enough electricity to power 350 homes. Throughout the development of wind turbines, however, energy companies have seen significant public opposition towards the tall white structures. The purpose of this research was to measure peoples' perceptions on wind turbine development throughout their growth, from proposal to existing phase. Three hypotheses were developed based on the participant's political affiliation, proximity and knowledge of wind turbines. To validate these hypotheses, participants were asked an array of questions regarding their perception on economic, environmental, and social impacts of wind turbines with an online service called Amazon Mechanical Turk. The responses were from residents living in the United States and required them to provide their zip code for subsequent analysis. The analysis from the data obtained suggests that participants are favorable towards wind turbine development and would be supportive of using the technology in their community. Political affiliation and proximity to the nearest wind turbine in any phase of development (proposal, construction, existing) were also analyzed to determine if they had an effect on a person's overall perception on wind turbines and their technology. From the analysis, political affiliation was seen to be an indirect factor to understanding favorability towards wind turbines; the more liberal you are, the more supportive you will be towards renewable energy use

  6. Landscape structure in a managed forest mosaic of the Southern Appalachian Mountains and its influence on songbirds and small mammals

    NASA Astrophysics Data System (ADS)

    Leimgruber, Peter

    Forests in the Appalachian Mountains have been severely affected by logging in the past and little old-growth is left. The remaining forests form a heterogeneous mosaic of different forest successions. A concern for conservation is how additional logging will alter the mosaic and its fauna. I studied the effects of logging on the landscape mosaic and how changes in the landscape structure influence small mammals and birds in the George Washington National Forest, Virginia. My dissertation also included research on how to improve techniques for landscape ecological studies, such as roadside monitoring of birds and mapping of forest resources using remote sensing and Geographic Information Systems (GIS). Because of the scale dependency of landscape-ecological relationships, I investigated how landscape structure in the forest mosaic changes with increasing scales. I determined threshold scales at which structure changed markedly. After establishing a baseline, I examined how logging affected the intensity and location of such thresholds. I found thresholds in landscape structure exist at 400-, 500-, and 800-m intervals from the outer edge of the cut. While logging did not change threshold location and intensity for global landscape indices, such as dominance and contagion, thresholds for focal indices, such as mean patch size and percent cover for early-successional forest, changed markedly. Using GIS, I determined how logging affected small mammals and birds at the landscape scale. I divided the landscape into three zones (zone 1, inside logged areas; zone 2, 20--400 m from logged areas; zone 3, 1000--1500 m from logged areas). Logging changed species presence and richness more drastically in close proximity of cuts than on the landscape and influenced birds more strongly than mammals. In the cuts, edge-adapted birds, such as the indigo bunting (Passerina cyanea), replaced forest interior species, such as the Acadian flycatcher (Empidonax virescens). Most

  7. SELMAP - SELEX affinity landscape MAPping of transcription factor binding sites using integrated microfluidics

    PubMed Central

    Chen, Dana; Orenstein, Yaron; Golodnitsky, Rada; Pellach, Michal; Avrahami, Dorit; Wachtel, Chaim; Ovadia-Shochat, Avital; Shir-Shapira, Hila; Kedmi, Adi; Juven-Gershon, Tamar; Shamir, Ron; Gerber, Doron

    2016-01-01

    Transcription factors (TFs) alter gene expression in response to changes in the environment through sequence-specific interactions with the DNA. These interactions are best portrayed as a landscape of TF binding affinities. Current methods to study sequence-specific binding preferences suffer from limited dynamic range, sequence bias, lack of specificity and limited throughput. We have developed a microfluidic-based device for SELEX Affinity Landscape MAPping (SELMAP) of TF binding, which allows high-throughput measurement of 16 proteins in parallel. We used it to measure the relative affinities of Pho4, AtERF2 and Btd full-length proteins to millions of different DNA binding sites, and detected both high and low-affinity interactions in equilibrium conditions, generating a comprehensive landscape of the relative TF affinities to all possible DNA 6-mers, and even DNA10-mers with increased sequencing depth. Low quantities of both the TFs and DNA oligomers were sufficient for obtaining high-quality results, significantly reducing experimental costs. SELMAP allows in-depth screening of hundreds of TFs, and provides a means for better understanding of the regulatory processes that govern gene expression. PMID:27628341

  8. SELMAP - SELEX affinity landscape MAPping of transcription factor binding sites using integrated microfluidics.

    PubMed

    Chen, Dana; Orenstein, Yaron; Golodnitsky, Rada; Pellach, Michal; Avrahami, Dorit; Wachtel, Chaim; Ovadia-Shochat, Avital; Shir-Shapira, Hila; Kedmi, Adi; Juven-Gershon, Tamar; Shamir, Ron; Gerber, Doron

    2016-01-01

    Transcription factors (TFs) alter gene expression in response to changes in the environment through sequence-specific interactions with the DNA. These interactions are best portrayed as a landscape of TF binding affinities. Current methods to study sequence-specific binding preferences suffer from limited dynamic range, sequence bias, lack of specificity and limited throughput. We have developed a microfluidic-based device for SELEX Affinity Landscape MAPping (SELMAP) of TF binding, which allows high-throughput measurement of 16 proteins in parallel. We used it to measure the relative affinities of Pho4, AtERF2 and Btd full-length proteins to millions of different DNA binding sites, and detected both high and low-affinity interactions in equilibrium conditions, generating a comprehensive landscape of the relative TF affinities to all possible DNA 6-mers, and even DNA10-mers with increased sequencing depth. Low quantities of both the TFs and DNA oligomers were sufficient for obtaining high-quality results, significantly reducing experimental costs. SELMAP allows in-depth screening of hundreds of TFs, and provides a means for better understanding of the regulatory processes that govern gene expression. PMID:27628341

  9. Seasonality of fire weather strongly influences fire regimes in South Florida savanna-grassland landscapes.

    PubMed

    Platt, William J; Orzell, Steve L; Slocum, Matthew G

    2015-01-01

    Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993-2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997-2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of

  10. Seasonality of fire weather strongly influences fire regimes in South Florida savanna-grassland landscapes.

    PubMed

    Platt, William J; Orzell, Steve L; Slocum, Matthew G

    2015-01-01

    Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993-2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997-2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of

  11. Influence of climate on landscape characteristics in safety assessments of repositories for radioactive wastes.

    PubMed

    Becker, J K; Lindborg, T; Thorne, M C

    2014-12-01

    In safety assessments of repositories for radioactive wastes, large spatial and temporal scales have to be considered when developing an approach to risk calculations. A wide range of different types of information may be required. Local to the site of interest, temperature and precipitation data may be used to determine the erosional regime (which may also be conditioned by the vegetation characteristics adopted, based both on climatic and other considerations). However, geomorphological changes may be governed by regional rather than local considerations, e.g. alteration of river base levels, river capture and drainage network reorganisation, or the progression of an ice sheet or valley glacier across the site. The regional climate is in turn governed by the global climate. In this work, a commentary is presented on the types of climate models that can be used to develop projections of climate change for use in post-closure radiological impact assessments of geological repositories for radioactive wastes. These models include both Atmosphere-Ocean General Circulation Models and Earth Models of Intermediate Complexity. The relevant outputs available from these models are identified and consideration is given to how these outputs may be used to inform projections of landscape development. Issues of spatial and temporal downscaling of climate model outputs to meet the requirements of local-scale landscape development modelling are also addressed. An example is given of how climate change and landscape development influence the radiological impact of radionuclides potentially released from the deep geological disposal facility for spent nuclear fuel that SKB (the Swedish Nuclear Fuel and Waste Management Company) proposes to construct at Forsmark, Sweden.

  12. Influence of climate on landscape characteristics in safety assessments of repositories for radioactive wastes.

    PubMed

    Becker, J K; Lindborg, T; Thorne, M C

    2014-12-01

    In safety assessments of repositories for radioactive wastes, large spatial and temporal scales have to be considered when developing an approach to risk calculations. A wide range of different types of information may be required. Local to the site of interest, temperature and precipitation data may be used to determine the erosional regime (which may also be conditioned by the vegetation characteristics adopted, based both on climatic and other considerations). However, geomorphological changes may be governed by regional rather than local considerations, e.g. alteration of river base levels, river capture and drainage network reorganisation, or the progression of an ice sheet or valley glacier across the site. The regional climate is in turn governed by the global climate. In this work, a commentary is presented on the types of climate models that can be used to develop projections of climate change for use in post-closure radiological impact assessments of geological repositories for radioactive wastes. These models include both Atmosphere-Ocean General Circulation Models and Earth Models of Intermediate Complexity. The relevant outputs available from these models are identified and consideration is given to how these outputs may be used to inform projections of landscape development. Issues of spatial and temporal downscaling of climate model outputs to meet the requirements of local-scale landscape development modelling are also addressed. An example is given of how climate change and landscape development influence the radiological impact of radionuclides potentially released from the deep geological disposal facility for spent nuclear fuel that SKB (the Swedish Nuclear Fuel and Waste Management Company) proposes to construct at Forsmark, Sweden. PMID:25255485

  13. Seasonality of Fire Weather Strongly Influences Fire Regimes in South Florida Savanna-Grassland Landscapes

    PubMed Central

    Platt, William J.; Orzell, Steve L.; Slocum, Matthew G.

    2015-01-01

    Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993–2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997–2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of

  14. The influence of anthropogenic landscape changes on weather in south Florida

    USGS Publications Warehouse

    Pielke, R.A.; Walko, R.L.; Steyaert, L.T.; Vidale, P.L.; Liston, G.E.; Lyons, W.A.; Chase, T.N.

    1999-01-01

    Using identical observed meteorology for lateral boundary conditions, the Regional Atmospheric Modeling System was integrated for July-August 1973 for south Florida. Three experiments were performed-one using the observed 1973 landscape, another the 1993 landscape, and the third the 1900 landscape, when the region was close to its natural state. Over the 2-month period, there was a 9% decrease in rainfall averaged over south Florida with the 1973 landscape and an 11% decrease with the 1993 landscape, as compared with the model results when the 1900 landscape is used. The limited available observations of trends in summer rainfall over this region are consistent with these trends.

  15. Influences of prior wildfires on vegetation response to subsequent fire in a reburned Southwestern landscape.

    PubMed

    Coop, Jonathan D; Parks, Sean A; McClernan, Sarah R; Holsinger, Lisa M

    2016-03-01

    Large and severe wildfires have raised concerns about the future of forested landscapes in the southwestern United States, especially under repeated burning. In 2011, under extreme weather and drought conditions, the Las Conchas fire burned over several previous burns as well as forests not recently exposed to fire. Our purpose was to examine the influences of prior wildfires on plant community composition and structure, subsequent burn severity, and vegetation response. To assess these relationships, we used satellite-derived measures of burn severity and a nonmetric multidimensional scaling of pre- and post- Las Conchas field samples. Earlier burns were associated with shifts from forested sites to open savannas and meadows, oak scrub, and ruderal communities. These non-forested vegetation types exhibited both resistance to subsequent fire, measured by reduced burn severity, and resilience to reburning, measured by vegetation recovery relative to forests not exposed to recent prior fire. Previous shifts toward non-forested states were strongly reinforced by reburning. Ongoing losses of forests and their ecological values confirm the need for restoration interventions. However, given future wildfire and climate projections, there may also be opportunities presented by transformations toward fire-resistant and resilient vegetation types within portions of the landscape. PMID:27209778

  16. Influence of landscape morphology and vegetation cover on the sampling of mixed plutonic bodies

    NASA Astrophysics Data System (ADS)

    Perugini, D.; Petrelli, M.; Poli, G.

    2007-05-01

    A plethora of evidence indicates that magma mixing processes can take place at any evolutionary stage of magmatic systems and that they are extremely common in both plutonic and volcanic environments. Furthermore, recent studies have shown that the magma mixing process is governed by chaotic dynamics whose evolution in space and time generates complex compositional patterns. The fact that magma mixing processes can produce igneous bodies exhibiting a large compositional complexity brings up the key question about the potential pitfalls that may be associated with the sampling of these systems for petrological studies. In particular, since commonly only exiguous portions of the whole magmatic system are available as outcrops for sampling, it is important to address the point whether the sampling may be considered representative of the complexity of the magmatic system. Here, we attempt to address this crucial point by performing numerical simulations of magma mixing processes in 3D, and by evaluating the best conditions for sampling by considering different landscape morphologies and percentages of vegetation cover. It is shown that the goodness of sampling is strongly dependant on the roughness of the landscape, with highly irregular morphologies being the best candidates to give the most complete information on the whole magma body. Vegetation cover, on the contrary, does not appear to significantly influence the representativeness of sampling.

  17. Influences of prior wildfires on vegetation response to subsequent fire in a reburned Southwestern landscape.

    PubMed

    Coop, Jonathan D; Parks, Sean A; McClernan, Sarah R; Holsinger, Lisa M

    2016-03-01

    Large and severe wildfires have raised concerns about the future of forested landscapes in the southwestern United States, especially under repeated burning. In 2011, under extreme weather and drought conditions, the Las Conchas fire burned over several previous burns as well as forests not recently exposed to fire. Our purpose was to examine the influences of prior wildfires on plant community composition and structure, subsequent burn severity, and vegetation response. To assess these relationships, we used satellite-derived measures of burn severity and a nonmetric multidimensional scaling of pre- and post- Las Conchas field samples. Earlier burns were associated with shifts from forested sites to open savannas and meadows, oak scrub, and ruderal communities. These non-forested vegetation types exhibited both resistance to subsequent fire, measured by reduced burn severity, and resilience to reburning, measured by vegetation recovery relative to forests not exposed to recent prior fire. Previous shifts toward non-forested states were strongly reinforced by reburning. Ongoing losses of forests and their ecological values confirm the need for restoration interventions. However, given future wildfire and climate projections, there may also be opportunities presented by transformations toward fire-resistant and resilient vegetation types within portions of the landscape.

  18. Water-regolith-energy Interaction in Landscape Evolution and Its Influence on Forming Asymmetric Landscape: An Example from the Shale Hills Critical Zone Observatory of Central Pennsylvania

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Slingerland, R. L.; Shi, Y.; Duffy, C.; West, N.

    2015-12-01

    Shale Hills Critical Zone Observatory (SSHCZO) is a 0.08 km2 first order experimental research catchment with relatively homogeneous bedrock, regolith and tectonic uplift, but with an asymmetric slope and thickness of regolith on the north- and south-facing hillslopes. In this paper, we use a hydrological-morphodynamic model (LE-PIHM), which links bedrock, soil, surface and subsurface water flow, plant, energy, and seasonal climate, to address the influence of water-regolith-energy interaction on soil creep process, the possible factors causing slope asymmetry and the spatial distribution of regolith transport at the SSHCZO. Two non-dimensional parameters were used to explore the competitive relationship between regolith diffusion and advection forming self-organized channel spacing, relief and slope length at steady state. Model simulation under seasonal meteorological forcing shows spatial variations of hillslope sediment fluxes. An experimental study using Beryllium 10 at the SSHCZO (West et al 2013) showed that a south-facing planar slope had a greater diffusion flux rate than a planar on north-facing slope. The model confirms this relationship in general although there are significant local variations. The largest regolith transport rate by overland flow (advection) occurs at the junctions of main channel and swales. The model simulation further suggests that north-south differences in diffusive flux may be a result of asymmetric solar insolation which affects freeze-thaw frequency and sediment transport through the process of soil creep. This study demonstrates the value of physically-based distributed landscape evolution model on estimating spatial distribution of regolith transport and highlights the critical transition zone.

  19. Factors influencing recall of childhood sexual abuse.

    PubMed

    Rogers, M L

    1995-10-01

    Selective literatures providing perspective on recall of childhood sexual abuse memories are reviewed. These include known patterns of autobiographical memories in adulthood, metacognitive mechanisms, interpersonal influences, and automatic cognitive processing which can influence judgments and reports of memory recall in children and adults. Some factors in adult experience such as mood state, presence of emotional disorders, past and current relationships, and participation in psychotherapy which can influence autobiographical memory and recall of childhood events are delineated. Available studies directly exploring recovered memories of childhood abuse are considered in light of these studies. Finally, some applications to clinical work and suggestions for future research are outlined.

  20. How does landscape structure influence catchment transit time across different geomorphic provinces?

    USGS Publications Warehouse

    Tetzlaff, D.; Seibert, J.; McGuire, K.J.; Laudon, H.; Burns, Douglas A.; Dunn, S.M.; Soulsby, C.

    2009-01-01

    Despite an increasing number of empirical investigations of catchment transit times (TTs), virtually all are based on individual catchments and there are few attempts to synthesize understanding across different geographical regions. Uniquely, this paper examines data from 55 catchments in five geomorphic provinces in northern temperate regions (Scotland, United States of America and Sweden). The objective is to understand how the role of catchment topography as a control on the TTs differs in contrasting geographical settings. Catchment inverse transit time proxies (ITTPs) were inferred by a simple metric of isotopic tracer damping, using the ratio of standard deviation of ??18O in streamwater to the standard deviation of ??18O in precipitation. Quantitative landscape analysis was undertaken to characterize the catchments according to hydrologically relevant topographic indices that could be readily determined from a digital terrain model (DTM). The nature of topographic controls on transit times varied markedly in different geomorphic regions. In steeper montane regions, there are stronger gravitational influences on hydraulic gradients and TTs tend to be lower in the steepest catchments. In provinces where terrain is more subdued, direct topographic control weakened; in particular, where flatter areas with less permeable soils give rise to overland flow and lower TTs. The steeper slopes within this flatter terrain appear to have a greater coverage of freely draining soils, which increase sub-surface flow, therefore increasing TTs. Quantitative landscape analysis proved a useful tool for intercatchment comparison. However, the critical influence of sub-surface permeability and connectivity may limit the transferability of predictive tools of hydrological function based on topographic parameters alone. Copyright ?? 2009 John Wiley & Sons, Ltd.

  1. Landscape transformation under influence of melting buried ice blocks (North Poland)

    NASA Astrophysics Data System (ADS)

    Słowiński, Michał; Błaszkiewicz, Mirosław; Brauer, Achim; Noryśkiewicz, Bożena; Ott, Florian; Tyszkowski, Sebastian

    2014-05-01

    The aim of the research was to decipher impacts, how dead ice melting can influence landscape transformation in the Lateglacial and early Holocene in Central Europe. Here, we present the paleoecological results from the middle section of the Wda river located in northern Poland (Central Europe), on the outwash plain formed during the Pomeranian phase of the last (Vistulian) glacial period ca 16,000 14C yrs BP. The Wda river has a typical polygenetic valley in young glacial areas of the northern central European lowlands. We reconstructed environmental changes using biotic proxies (plant macrofossil and pollen analyses) and geomorphological investigations. Abrupt changes in lithology and sediment structures show rapid changes and threshold processes in environmental conditions. The AMS 14C dating of terrestrial plant remains reveals an age for the basal sediments of 11 223 ± 23 cal yr BP coinciding with the Preboreal biozone. The results show the existence of buried ice blocks in northern Poland even at the beginning of the Holocene proving that locally discontinuous permafrost was still present at that time. Our study demonstrates a strong influence of melting buried ice blocks on the geomorphological development, hydrological changes in the catchment, and the biotic environment even in the early Holocene. This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution (ICLEA) of the Helmholtz Association. Financial support by the COST Action ES0907 INTIMATE is gratefully acknowledged. The research was supported by the National Science Centre Poland (grants No. NN 306085037 and NCN 2011/01/B/ST10/07367).

  2. Factors Influencing the Fatigue Strength of Materials

    NASA Technical Reports Server (NTRS)

    Bollenrath, F

    1941-01-01

    A number of factors are considered which influence the static and fatigue strength of materials under practical operating conditions as contrasted with the relations obtaining under conditions of the usual testing procedure. Such factors are interruptions in operation, periodically fluctuating stress limits and mean stresses with periodic succession of several groups and stress states, statistical changes and succession of stress limits and mean stresses, frictional corrosion at junctures, and notch effects.

  3. Oasis dynamics change and its influence on landscape pattern on Jinta oasis in arid China from 1963a to 2010a: Integration of multi-source satellite images

    NASA Astrophysics Data System (ADS)

    Xie, Yuchu; Gong, Jie; Sun, Peng; Gou, Xiaohua

    2014-12-01

    As one of the vital research highlights of global land use and cover change, oasis change and its interaction with landscape pattern have been regarded as an important content of regional environmental change research in arid areas. Jinta oasis, a typical agricultural oasis characterized by its dramatic exploitation and use of water and land resources in Hexi corridor, northwest arid region in China, was selected as a case to study the spatiotemporal oasis change and its effects on oasis landscape pattern. Based on integration of Keyhole satellite photographs, KATE-200 photographs, Landsat MSS, TM and ETM+ images, we evaluated and analyzed the status, trend and spatial pattern change of Jinta oasis and the characteristics of landscape pattern change by a set of mathematical models and combined this information with landscape metrics and community surveys. During the period of 1963a-2010a, Jinta oasis expanded gradually with an area increase of 219.15 km2, and the conversion between oasis and desert was frequent with a state of “imbalance-balance-extreme imbalance conditions”. Moreover, most of the changes took place in the ecotone between oasis and desert and the interior of oasis due to the reclamation of abandoned land, such as Yangjingziwan and Xiba townships. Furthermore, the area, size and spatial distribution of oasis were influenced by human activities and resulted in fundamental changes of oasis landscape pattern. The fractal characteristics, dispersion degree and fragmentation of Jinta oasis decreased and the oasis landscape tended to be simple and uniform. Oasis change trajectories and its landscape pattern were mainly influenced by water resource utilization, policies (especially land policies), demographic factors, technological advancements, as well as regional economic development. We found that time series analysis of multi-source remote sensing images and the application of an oasis change model provided a useful approach to monitor oasis change

  4. Landscape Diversity and Crop Vigor Influence Biological Control of the Western Grape Leafhopper (E. elegantula Osborn) in Vineyards

    PubMed Central

    Wilson, Houston; Miles, Albie F.; Daane, Kent M.; Altieri, Miguel A.

    2015-01-01

    This study evaluated how the proportional area of natural habitat surrounding a vineyard (i.e. landscape diversity) worked in conjunction with crop vigor, cultivar and rootstock selection to influence biological control of the western grape leafhopper (Erythroneura elegantula Osborn). The key natural enemies of E. elegantula are Anagrus erythroneurae S. Trjapitzin & Chiappini and A. daanei Triapitsyn, both of which are likely impacted by changes in landscape diversity due to their reliance on non-crop habitat to successfully overwinter. Additionally, E. elegantula is sensitive to changes in host plant quality which may influence densities on specific cultivars, rootstocks and/or vines with increased vigor. From 2010–2013, data were collected on natural enemy and leafhopper densities, pest parasitism rates and vine vigor from multiple vineyards that represented a continuum of landscape diversity. Early in the season, vineyards in more diverse landscapes had higher Anagrus spp. densities and lower E. elegantula densities, which led to increased parasitism of E. elegantula. Although late season densities of E. elegantula tended to be lower in vineyards with higher early season parasitism rates and lower total petiole nitrogen content, they were also affected by rootstock and cultivar. While diverse landscapes can support higher natural enemy populations, which can lead to increased biological control, leafhopper densities also appear to be mediated by cultivar, rootstock and vine vigor. PMID:26555074

  5. Landscape Diversity and Crop Vigor Influence Biological Control of the Western Grape Leafhopper (E. elegantula Osborn) in Vineyards.

    PubMed

    Wilson, Houston; Miles, Albie F; Daane, Kent M; Altieri, Miguel A

    2015-01-01

    This study evaluated how the proportional area of natural habitat surrounding a vineyard (i.e. landscape diversity) worked in conjunction with crop vigor, cultivar and rootstock selection to influence biological control of the western grape leafhopper (Erythroneura elegantula Osborn). The key natural enemies of E. elegantula are Anagrus erythroneurae S. Trjapitzin & Chiappini and A. daanei Triapitsyn, both of which are likely impacted by changes in landscape diversity due to their reliance on non-crop habitat to successfully overwinter. Additionally, E. elegantula is sensitive to changes in host plant quality which may influence densities on specific cultivars, rootstocks and/or vines with increased vigor. From 2010-2013, data were collected on natural enemy and leafhopper densities, pest parasitism rates and vine vigor from multiple vineyards that represented a continuum of landscape diversity. Early in the season, vineyards in more diverse landscapes had higher Anagrus spp. densities and lower E. elegantula densities, which led to increased parasitism of E. elegantula. Although late season densities of E. elegantula tended to be lower in vineyards with higher early season parasitism rates and lower total petiole nitrogen content, they were also affected by rootstock and cultivar. While diverse landscapes can support higher natural enemy populations, which can lead to increased biological control, leafhopper densities also appear to be mediated by cultivar, rootstock and vine vigor. PMID:26555074

  6. Landscape Diversity and Crop Vigor Influence Biological Control of the Western Grape Leafhopper (E. elegantula Osborn) in Vineyards.

    PubMed

    Wilson, Houston; Miles, Albie F; Daane, Kent M; Altieri, Miguel A

    2015-01-01

    This study evaluated how the proportional area of natural habitat surrounding a vineyard (i.e. landscape diversity) worked in conjunction with crop vigor, cultivar and rootstock selection to influence biological control of the western grape leafhopper (Erythroneura elegantula Osborn). The key natural enemies of E. elegantula are Anagrus erythroneurae S. Trjapitzin & Chiappini and A. daanei Triapitsyn, both of which are likely impacted by changes in landscape diversity due to their reliance on non-crop habitat to successfully overwinter. Additionally, E. elegantula is sensitive to changes in host plant quality which may influence densities on specific cultivars, rootstocks and/or vines with increased vigor. From 2010-2013, data were collected on natural enemy and leafhopper densities, pest parasitism rates and vine vigor from multiple vineyards that represented a continuum of landscape diversity. Early in the season, vineyards in more diverse landscapes had higher Anagrus spp. densities and lower E. elegantula densities, which led to increased parasitism of E. elegantula. Although late season densities of E. elegantula tended to be lower in vineyards with higher early season parasitism rates and lower total petiole nitrogen content, they were also affected by rootstock and cultivar. While diverse landscapes can support higher natural enemy populations, which can lead to increased biological control, leafhopper densities also appear to be mediated by cultivar, rootstock and vine vigor.

  7. Factors Influencing Learning at a Community College.

    ERIC Educational Resources Information Center

    Johnson, Marvin L.

    The Walberg Educational Productivity Model theorizes that learning in its affective, behavioral, and cognitive aspects is causally influenced by factors in the areas of individual aptitude (i.e., prior achievement, age or stage of maturation, and motivation), instructional treatment (i.e., quantity of time spent in learning situations and…

  8. Factors Influencing Employee Learning in Small Businesses

    ERIC Educational Resources Information Center

    Coetzer, Alan; Perry, Martin

    2008-01-01

    Purpose: The purpose of this research is to identify key factors influencing employee learning from the perspective of owners/managers. Design/methodology/research: Data were gathered from owners/managers in a total of 27 small manufacturing and services firms through interviews and analysed using content analytic procedures. Findings: The…

  9. Technology Education Graduate Education: Factors Influencing Participation.

    ERIC Educational Resources Information Center

    Cardon, Phillip L.; Rogers, George E.

    A modified Delphi technique was used to identify the factors that positively influence technology education teachers' decision to enroll in graduate education programs and the barriers to their enrollment in advanced degree programs. Two pairs of Delphi panels were established. The doctoral panels consisted of 15 recent doctoral graduates and 30…

  10. Factors Influencing School Connectedness: Chinese Adolescents' Perspectives

    ERIC Educational Resources Information Center

    Yuen, Mantak; Lau, Patrick S. Y.; Lee, Queenie A. Y.; Gysbers, Norman C.; Chan, Raymond M. C.; Fong, Ricci W.; Chung, Y. B.; Shea, Peter M. K.

    2012-01-01

    This study explored the concept of school connectedness and the factors that may influence its development with a sample of Chinese adolescents. Six focus groups involving 52 high school students were conducted using a set of predetermined discussion topics. Results indicated that the students fully understood the notion of school connectedness…

  11. Social Factors Influencing Child Health in Ghana

    PubMed Central

    Quansah, Emmanuel; Ohene, Lilian Akorfa; Norman, Linda; Mireku, Michael Osei; Karikari, Thomas K.

    2016-01-01

    Objectives Social factors have profound effects on health. Children are especially vulnerable to social influences, particularly in their early years. Adverse social exposures in childhood can lead to chronic disorders later in life. Here, we sought to identify and evaluate the impact of social factors on child health in Ghana. As Ghana is unlikely to achieve the Millennium Development Goals’ target of reducing child mortality by two-thirds between 1990 and 2015, we deemed it necessary to identify social determinants that might have contributed to the non-realisation of this goal. Methods ScienceDirect, PubMed, MEDLINE via EBSCO and Google Scholar were searched for published articles reporting on the influence of social factors on child health in Ghana. After screening the 98 articles identified, 34 of them that met our inclusion criteria were selected for qualitative review. Results Major social factors influencing child health in the country include maternal education, rural-urban disparities (place of residence), family income (wealth/poverty) and high dependency (multiparousity). These factors are associated with child mortality, nutritional status of children, completion of immunisation programmes, health-seeking behaviour and hygiene practices. Conclusions Several social factors influence child health outcomes in Ghana. Developing more effective responses to these social determinants would require sustainable efforts from all stakeholders including the Government, healthcare providers and families. We recommend the development of interventions that would support families through direct social support initiatives aimed at alleviating poverty and inequality, and indirect approaches targeted at eliminating the dependence of poor health outcomes on social factors. Importantly, the expansion of quality free education interventions to improve would-be-mother’s health knowledge is emphasised. PMID:26745277

  12. Influence of Landscape Morphology and Vegetation Cover on the Sampling of Mixed Igneous Bodies

    NASA Astrophysics Data System (ADS)

    Perugini, Diego; Petrelli, Maurizio; Poli, Giampiero

    2010-05-01

    cover is generated using a random Brownian motion process in 2D. Such an approach allows us to produce vegetation patches that closely match the general topology of natural vegetation (e.g., Mandelbrot, 1982). Results show that the goodness of sampling is strongly dependant on the roughness of the landscape, with highly irregular morphologies being the best candidates to give the most complete information on the whole magma body. Conversely, sampling on flat or nearly flat surfaces should be avoided because they may contain misleading information about the magmatic system. Contrary to common sense, vegetation cover does not appear to significantly influence the representativeness of sampling if sample collection occurs on topographically irregular outcrops. Application of the proposed method for sampling area selection is straightforward. The irregularity of natural landscapes and the percentage of vegetation can be estimated by using natural landscapes extracted from digital elevation models (DEM) of the Earth's surface and satellite images by employing a variety of methods (e.g., Develi and Babadagli, 1998), thus giving one the opportunity to select a priori the best outcrops for sampling. References Bateman R (1995) The interplay between crystallization, replenishment and hybridization in large felsic magma chambers. Earth Sci Rev 39: 91-106 Develi K, Babadagli T (1998) Quantfication of natural fracture surfaces using fractal geometry. Math Geol 30: 971-998 Fournier A, Fussel D, Carpenter L (1982) Computer rendering of stochastic models. Comm ACM 25: 371-384 Galluccio S, Vulpiani A (1994) Stretching of material lines and surfaces in systems with Lagrangian chaos. Physica A 212: 75-98 Mandelbrot BB (1982) The fractal geometry of nature. W. H. Freeman, San Francisco Perugini D, Petrelli M, Poli G (2007) A Virtual Voyage through 3D Structures Generated by Chaotic Mixing of Magmas and Numerical Simulations: a New Approach for Understanding Spatial and Temporal Complexity

  13. Factors that influence women's dispositions toward science

    NASA Astrophysics Data System (ADS)

    Atria, Catherine Graczyk

    Females have been underrepresented in the study of science and science careers for decades although advancements have been made in closing this gender gap, the gap persists particularly in the physical sciences. Variables which influence a woman's desire to pursue and maintain a science course of study and career must be discovered. The United States lags behind other industrialized countries in the fields of science, math, and engineering. Females comprise an estimated half of the population; their potential contributions cannot be ignored or overlooked. This retrospective research study explores the personal experiences of ten women enrolled in science majors, with science related career plans. The goal of this study is to describe the factors that influence the participants' interest in science. The findings, the effect of science coursework, science teachers' personality and manner, other influential educational personnel, role models and mentors, external influences exclusive of school, parental influence, locus of control and positive attitudes toward science confirm what other researchers have found.

  14. Factors influencing the inhibition of protein kinases.

    PubMed

    Brockhoff, Marielle; Hau, Jean-Christophe; Fontana, Patrizia; Zimmermann, Catherine; Pover, Alain De; Erdmann, Dirk; Chène, Patrick

    2012-04-01

    The protein kinase field is a very active research area in the pharmaceutical industry and many activities are ongoing to identify inhibitors of these proteins. The design of new chemical entities with improved pharmacological properties requires a deeper understanding of the factors that modulate inhibitor-kinase interactions. In this report, we studied the effect of two of these factors--the magnesium ion cofactor and the protein substrate--on inhibitors of the type I insulin-like growth factor receptor. Our results show that the concentration of magnesium ion influences the potency of adenosine triphosphate (ATP) competitive inhibitors, suggesting an explanation for the observation that such compounds retain their nanomolar potency in cells despite the presence of millimolar levels of ATP. We also showed that the peptidic substrate affects the potency of these inhibitors in a different manner, suggesting that the influence of this substrate on compound potency should be taken into consideration during drug discovery.

  15. Landscape-level influences of terrestrial snake occupancy within the southeastern United States.

    PubMed

    Steen, David A; McClure, Christopher J W; Brock, Jean C; Rudolph, D Craig; Pierce, Josh B; Lee, James R; Humphries, W Jeffrey; Gregory, Beau B; Sutton, William B; Smith, Lora L; Baxley, Danna L; Stevenson, Dirk J; Guyer, Craig

    2012-06-01

    Habitat loss and degradation are thought to be the primary drivers of species extirpations, but for many species we have little information regarding specific habitats that influence occupancy. Snakes are of conservation concern throughout North America, but effective management and conservation are hindered by a lack of basic natural history information and the small number of large-scale studies designed to assess general population trends. To address this information gap, we compiled detection/nondetection data for 13 large terrestrial species from 449 traps located across the southeastern United States, and we characterized the land cover surrounding each trap at multiple spatial scales (250-, 500-, and 1000-m buffers). We used occupancy modeling, while accounting for heterogeneity in detection probability, to identify habitat variables that were influential in determining the presence of a particular species. We evaluated 12 competing models for each species, representing various hypotheses pertaining to important habitat features for terrestrial snakes. Overall, considerable interspecific variation existed in important habitat variables and relevant spatial scales. For example, kingsnakes (Lampropeltis getula) were negatively associated with evergreen forests, whereas Louisiana pinesnake (Pituophis ruthveni) occupancy increased with increasing coverage of this forest type. Some species were positively associated with grassland and scrub/shrub (e.g., Slowinski's cornsnake, Elaphe slowinskii) whereas others, (e.g., copperhead, Agkistrodon contortrix, and eastern diamond-backed rattlesnake, Crotalus adamanteus) were positively associated with forested habitats. Although the species that we studied may persist in varied landscapes other than those we identified as important, our data were collected in relatively undeveloped areas. Thus, our findings may be relevant when generating conservation plans or restoration goals. Maintaining or restoring landscapes that

  16. Influence of organizational factors on safety

    SciTech Connect

    Haber, S.B.; Metlay, D.S.; Crouch, D.A.

    1990-01-01

    There is a need for a better understanding of exactly how organizational management factors at a nuclear power plant (NPP) affect plant safety performance, either directly or indirectly, and how these factors might be observed, measured, and evaluated. The purpose of this research project is to respond to that need by developing a general methodology for characterizing these organizational and management factors, systematically collecting information on their status and integrating that information into various types of evaluative activities. Research to date has included the development of the Nuclear Organization and Management Analysis Concept (NOMAC) of a NPP, the identification of key organizational and management factors, and the identification of the methods for systematically measuring and analyzing the influence of these factors on performance. Most recently, two field studies, one at a fossil fuel plant and the other at a NPP, were conducted using the developed methodology. Results are presented from both studies highlighting the acceptability, practicality, and usefulness of the methods used to assess the influence of various organizational and management factors including culture, communication, decision-making, standardization, and oversight. 6 refs., 3 figs., 1 tab.

  17. Factors influencing patients' dignity: A qualitative study.

    PubMed

    Manookian, Arpi; Cheraghi, Mohammad A; Nasrabadi, Alireza N

    2014-05-01

    Dignity represents the essence of nursing care; hence, nurses are professionally responsible for promoting understanding about the promotion, provision, and preservation of every patient's dignity, while considering contextual differences. The aim of this study was to explore the factors that influence, promote, or compromise patient dignity. A purposeful sample of 14 participants with hospitalization experience was chosen, and individual in-depth semi-structured interviews were conducted for data collection. Using inductive content analysis, the themes and subthemes related to factors influencing patients' dignity were explored: "persona" ("personal beliefs" and "personal characteristics"), "communication behaviors" ("verbal interaction," "body language," "compassionate behavior," and "devoting enough time"), and "staff conduct" ("professional commitment," "adequate human resources," and "staff's proficiency and competency"). The findings revealed that it is essential to expand nurses' insights and knowledge about preserving patients' dignity and the factors that influence these. Recognizing and focusing on these factors will help nurses to establish practical measures for preserving and promoting patients' dignity and providing more dignified care at the bedside.

  18. Political and economic factors influencing contraceptive uptake.

    PubMed

    Sai, F T

    1993-01-01

    International, national and local level politics influence the uptake of contraception through consensuses, laws, financial and moral support or the creation of an enabling atmosphere. Opposition to contraception generally comes from some churches and groups opposed to particular technologies. Socio-economic factors, particularly education, the health care system and the perceived or actual cost of fertility regulation as compared to benefits expected from children also powerfully influence contraceptive use. For many poor women in developing countries their powerlessness in relation to their male partners is an important obstacle.

  19. Crushing runtimes in adiabatic quantum computation with Energy Landscape Manipulation (ELM): Application to Quantum Factoring

    NASA Astrophysics Data System (ADS)

    Dattani, Nike; Tanburn, Richard; Lunt, Oliver

    We introduce two methods for speeding up adiabatic quantum computations by increasing the energy between the ground and first excited states. Our methods are even more general. They can be used to shift a Hamiltonian's density of states away from the ground state, so that fewer states occupy the low-lying energies near the minimum, hence allowing for faster adiabatic passages to find the ground state with less risk of getting caught in an undesired low-lying excited state during the passage. Even more generally, our methods can be used to transform a discrete optimization problem into a new one whose unique minimum still encodes the desired answer, but with the objective function's values forming a different landscape. Aspects of the landscape such as the objective function's range, or the values of certain coefficients, or how many different inputs lead to a given output value, can be decreased *or* increased. One of the many examples for which these methods are useful is in finding the ground state of a Hamiltonian using NMR. We apply our methods to an AQC algorithm for integer factorization, and the first method reduces the maximum runtime in our example by up to 754%, and the second method reduces the maximum runtime of another example by up to 250%.

  20. Characterizing scale-specific environmental factors affecting soil organic carbon along two landscape transects.

    PubMed

    She, Dongli; Cao, Yutong; Chen, Qian; Yu, Shuang'en

    2016-09-01

    Soil organic carbon (SOC) is one of the most important soil properties affecting many other soil and environmental properties and processes. In order to understand and manage SOC effectively, it is important to identify the scale-specific main factors affecting SOC distributions, which in this study occurred in a watershed on the Loess Plateau. Two transects were selected that passed along the upper slopes on each side of the main gully of the Liudaogou watershed. Transect 1 (3411-m length) had 27 sampling sites at 131-m intervals; transect 2 (3597 m length) had 30 sampling sites at 124-m intervals. The two transects were chosen in order to compare landscape patterns of differing complexity that were in close proximity, which reduced the effects of factors that would be caused by different locations. The landscape of transect 1 was more complex due to the greater diversity in cultivation. Multivariate empirical mode decomposition (MEMD) decomposed the total variation in SOC and five selected environmental factors into four intrinsic mode functions (IMFs) and a residual according to the scale of occurrence. Scale-specific correlation analysis was used to identify significant relationships between SOC and the environmental factors. The dominant scales were those that were the largest contributors to the total SOC variance; for transect 1, this was the IMF 1 (scale of 403 m), whereas for transect 2, it was the medium scale of the IMF 2 (scale of 688 m). For both transects, vegetation properties (vegetation cover and aboveground biomass) were the main factors affecting SOC distributions at their respective dominant scales. At each scale, the main effective factors could be identified although at the larger scales, their contributions to the overall variance were almost negligible. The distributions of SOC and the factors affecting it were found to be scale dependent. The results of this study highlighted the suitability of the MEMD method in revealing the main scale

  1. The Influence of Landscape Drainage on Biogeochemical Cycling of Carbon in Agricultural Ecosystems

    NASA Astrophysics Data System (ADS)

    Dalzell, B. J.; King, J. Y.; Mulla, D. J.; Finlay, J. C.; Sands, G. R.

    2008-12-01

    The movement of water through agricultural ecosystems is often modified by the presence of open ditches and subsurface tile drainage systems. Despite the common occurrence of these practices, particularly in the corn- and soybean-producing regions of the midwestern United States, much remains unknown about how altered drainage patterns may influence carbon export from agricultural landscapes. In this study, we examined the role of subsurface drainage systems on the quantity and quality of dissolved carbon export from experimental agricultural fields located in south-central Minnesota. Results from two years of observations show that fields with more intense drainage designs (e.g., greater density of subsurface drain lines) have dissolved organic carbon (DOC) concentrations that are similar to conventionally drained fields. However, fields with more intense drainage exhibit greater annual DOC loads due to higher water yields resulting from more intense drainage. In contrast, dissolved inorganic carbon (DIC) concentrations were consistently greater in fields with more intense drainage practices across all flow conditions. Our ongoing work is focused on determining if these differences in DIC concentrations are the result of either increased weathering or increased soil/plant root respiration resulting in increased soil CO2 concentrations. Molecular weight characterization of samples from our experimental fields shows that DOC from subsurface tile drainage is generally comprised of low molecular weight compounds. This low molecular weight signal is less apparent in samples from downstream ditch and river sites which are dominated by higher molecular weight compounds; suggesting that differences in organic matter source and/or processing are apparent over spatial scales transitioning from the field to small watershed. Overall, these results show that subsurface drainage practices fundamentally alter annual DOC and DIC carbon export from agricultural ecosystems as well

  2. Hurricane Katrina-induced forest damage in relation to ecological factors at landscape scale.

    PubMed

    Wang, Fugui; Xu, Y Jun

    2009-09-01

    Forest stand stability to strong winds such as hurricanes has been found to be associated with a number of forest, soil and topography factors. In this study, through applying geographic information system (GIS) and logit regression, we assessed effects of forest characteristics and site conditions on pattern, severity and probability of Hurricane Katrina disturbance to forests in the Lower Pearl River Valley, USA. The factors included forest type, forest coverage, stand density, soil great group, elevation, slope, aspect, and stream buffer zone. Results showed that Hurricane Katrina damaged 60% of the total forested land in the region. The distribution and intensity of the hurricane disturbance varied across the landscape, with the bottomland hardwood forests on river floodplains most severely affected. All these factors had a variety of effects on vulnerability of the forests to the hurricane disturbance and thereby spatial patterns of the disturbance. Soil groups and stand factors including forest types, forest coverage and stand density contributed to 85% of accuracy in modeling the probability of the hurricane disturbance to forests in this region. Besides assessment of Katrina's damage, this study elucidates the great usefulness of remote sensing and GIS techniques combined with statistics modeling in assessment of large-scale risks of hurricane damage to coastal forests.

  3. Where wolves kill moose: the influence of prey life history dynamics on the landscape ecology of predation.

    PubMed

    Montgomery, Robert A; Vucetich, John A; Roloff, Gary J; Bump, Joseph K; Peterson, Rolf O

    2014-01-01

    The landscape ecology of predation is well studied and known to be influenced by habitat heterogeneity. Little attention has been given to how the influence of habitat heterogeneity on the landscape ecology of predation might be modulated by life history dynamics of prey in mammalian systems. We demonstrate how life history dynamics of moose (Alces alces) contribute to landscape patterns in predation by wolves (Canis lupus) in Isle Royale National Park, Lake Superior, USA. We use pattern analysis and kernel density estimates of moose kill sites to demonstrate that moose in senescent condition and moose in prime condition tend to be wolf-killed in different regions of Isle Royale in winter. Predation on senescent moose was clustered in one kill zone in the northeast portion of the island, whereas predation on prime moose was clustered in 13 separate kill zones distributed throughout the full extent of the island. Moreover, the probability of kill occurrence for senescent moose, in comparison to prime moose, increased in high elevation habitat with patches of dense coniferous trees. These differences can be attributed, at least in part, to senescent moose being more vulnerable to predation and making different risk-sensitive habitat decisions than prime moose. Landscape patterns emerging from prey life history dynamics and habitat heterogeneity have been observed in the predation ecology of fish and insects, but this is the first mammalian system for which such observations have been made. PMID:24622241

  4. Where wolves kill moose: the influence of prey life history dynamics on the landscape ecology of predation.

    PubMed

    Montgomery, Robert A; Vucetich, John A; Roloff, Gary J; Bump, Joseph K; Peterson, Rolf O

    2014-01-01

    The landscape ecology of predation is well studied and known to be influenced by habitat heterogeneity. Little attention has been given to how the influence of habitat heterogeneity on the landscape ecology of predation might be modulated by life history dynamics of prey in mammalian systems. We demonstrate how life history dynamics of moose (Alces alces) contribute to landscape patterns in predation by wolves (Canis lupus) in Isle Royale National Park, Lake Superior, USA. We use pattern analysis and kernel density estimates of moose kill sites to demonstrate that moose in senescent condition and moose in prime condition tend to be wolf-killed in different regions of Isle Royale in winter. Predation on senescent moose was clustered in one kill zone in the northeast portion of the island, whereas predation on prime moose was clustered in 13 separate kill zones distributed throughout the full extent of the island. Moreover, the probability of kill occurrence for senescent moose, in comparison to prime moose, increased in high elevation habitat with patches of dense coniferous trees. These differences can be attributed, at least in part, to senescent moose being more vulnerable to predation and making different risk-sensitive habitat decisions than prime moose. Landscape patterns emerging from prey life history dynamics and habitat heterogeneity have been observed in the predation ecology of fish and insects, but this is the first mammalian system for which such observations have been made.

  5. Where Wolves Kill Moose: The Influence of Prey Life History Dynamics on the Landscape Ecology of Predation

    PubMed Central

    Montgomery, Robert A.; Vucetich, John A.; Roloff, Gary J.; Bump, Joseph K.; Peterson, Rolf O.

    2014-01-01

    The landscape ecology of predation is well studied and known to be influenced by habitat heterogeneity. Little attention has been given to how the influence of habitat heterogeneity on the landscape ecology of predation might be modulated by life history dynamics of prey in mammalian systems. We demonstrate how life history dynamics of moose (Alces alces) contribute to landscape patterns in predation by wolves (Canis lupus) in Isle Royale National Park, Lake Superior, USA. We use pattern analysis and kernel density estimates of moose kill sites to demonstrate that moose in senescent condition and moose in prime condition tend to be wolf-killed in different regions of Isle Royale in winter. Predation on senescent moose was clustered in one kill zone in the northeast portion of the island, whereas predation on prime moose was clustered in 13 separate kill zones distributed throughout the full extent of the island. Moreover, the probability of kill occurrence for senescent moose, in comparison to prime moose, increased in high elevation habitat with patches of dense coniferous trees. These differences can be attributed, at least in part, to senescent moose being more vulnerable to predation and making different risk-sensitive habitat decisions than prime moose. Landscape patterns emerging from prey life history dynamics and habitat heterogeneity have been observed in the predation ecology of fish and insects, but this is the first mammalian system for which such observations have been made. PMID:24622241

  6. Multiple Landscape Factors Affect the Resilience of a Mixed Land Cover Watershed

    NASA Astrophysics Data System (ADS)

    Golden, H. E.; Lane, C.; Prues, A. G.; D'Amico, E.

    2015-12-01

    Human activities can stimulate the physical and chemical properties of streams to move beyond their background conditions, thereby facilitating the transition of these factors to stressors that affect watershed resilience. This is particularly true in mixed land cover watersheds. We quantify and explore the statistical nonlinear relationships between watershed and buffer-scale factors and nutrient (nitrite-nitrate (NO2-NO3), total Kjeldahl nitrogen (TKN), total phosphorus (TP)) concentrations, in addition to a multi-metric Index of Biotic Integrity (IBI), in a mesoscale mixed land cover watershed. Our goal is to contribute to a better understanding of the potentially numerous landscape and near-stream hydrological and biogeochemical factors that affect watershed resiliency - as inferred from in-stream nutrient levels and biological condition. We used a boosted regression tree approach, which quantifies nonlinear relationships and variable interactions, to develop watershed and 200 m buffer scale models for each chemical constituent and the annual IBI score. We developed nutrient models for the spring and summer seasons. Two primary factors - location within the watershed and percentage of urban land cover in the watershed or buffer - emerged as important explanatory variables in most nutrient and IBI models. Geographic location (i.e., latitude and longitude) interacted with other factors to explain the variability in summer NO2-NO3 concentrations and IBI scores and suggested that location might be associated with indicators of sources (e.g., land cover) and runoff potential (e.g., soil and topographic factors). Runoff indicators (e.g., Hydrologic Soil Group D and Topographic Wetness Indices) explained a substantial portion of the variability in nutrient concentrations as did point sources for TP in the summer months. Our overall approach confirms that it is important to consider multiple and often interacting factors when managing for watershed resilience.

  7. Factors influencing public participation in biobanking.

    PubMed

    Ahram, Mamoun; Othman, Areej; Shahrouri, Manal; Mustafa, Ebtihal

    2014-04-01

    A diversity of public participation in biobanking is a highlight for the success of biobanks. It was previously reported that only two-thirds of Jordanians expressed interest in biobanking. To promote public involvement in a biobank, it is imperative to determine the aspects that influence the decision-making to participate. On the basis of a national survey involving 3196 respondents, the influence of 13 biobanking factors was assessed, including returning research results, privacy, freedom of choice, uncertainties about research, monetary and health considerations, and personal belief. Perception toward each factor was also correlated with willingness to participate in a biobank. A considerable number of respondents indicated returning research results as influential in their decision to become biobank donors. Interestingly, whereas the positive perception of availability of general results (39%) correlated with willingness to donate for biobanking, the negative view of unavailability of individualized results (47%) did not correlate with unwillingness. Religious permission of sample donation for research had the strongest positive influence (61%) and the highest correlation to participate among positively perceived factors. Unspecified research was highly indicated as a negative factor (45%), but did not correlate with unwillingness to become a biobank donor, whereas allowed withdrawal had a positive effect (31%) and correlation to contribute to biobanking. The negative perception of accessing medical information (9.5%) and re-contact (8.5%) had the strongest correlation with unwillingness to donate to a biobank. These results may provide an insight into how to formulate strategies to promote public participation in biomedical research and biobanking. PMID:23921537

  8. A landscape perspective on bat foraging ecology along rivers: does channel confinement and insect availability influence the response of bats to aquatic resources in riverine landscapes?

    PubMed

    Hagen, Elizabeth M; Sabo, John L

    2011-07-01

    River and riparian areas provide an important foraging habitat for insectivorous bats owing to high insect availability along waterways. However, structural characteristics of the riverine landscape may also influence the location of foraging bats. We used bat detectors to compare bat activity longitudinally along river reaches with contrasting channel confinement, ratio of valley floor width to active channel width, and riparian vegetation, and laterally with distance from the river along three different reach types. We measured rates of insect emergence from the river and aerial insect availability above the river and laterally up to 50-m into the riparian habitat in order to assess the relationship between food resources and insectivorous bat activity. Longitudinally, bat activity was concentrated along confined reaches in comparison to unconfined reaches but was not related to insect availability. Laterally, bats tracked exponential declines in aquatic insects with distance from the river. These data suggest that along the lateral dimension bats track food resources, but that along the longitudinal dimension channel shape and landscape structure determine bat distributions more than food resources.

  9. Influence of management history and landscape variables on soil organic carbon and soil redistribution

    USGS Publications Warehouse

    Venteris, E.R.; McCarty, G.W.; Ritchie, J.C.; Gish, T.

    2004-01-01

    Controlled studies to investigate the interaction between crop growth, soil properties, hydrology, and management practices are common in agronomy. These sites (much as with real world farmland) often have complex management histories and topographic variability that must be considered. In 1993 an interdisiplinary study was started for a 20-ha site in Beltsville, MD. Soil cores (271) were collected in 1999 in a 30-m grid (with 5-m nesting) and analyzed as part of the site characterization. Soil organic carbon (SOC) and 137Cesium (137Cs) were measured. Analysis of aerial photography from 1992 and of farm management records revealed that part of the site had been maintained as a swine pasture and the other portion as cropped land. Soil properties, particularly soil redistribution and SOC, show large differences in mean values between the two areas. Mass C is 0.8 kg m -2 greater in the pasture area than in the cropped portion. The pasture area is primarily a deposition site, whereas the crop area is dominated by erosion. Management influence is suggested, but topographic variability confounds interpretation. Soil organic carbon is spatially structured, with a regionalized variable of 120 m. 137Cs activity lacks spatial structure, suggesting disturbance of the profile by animal activity and past structures such as swine shelters and roads. Neither SOC nor 137Cs were strongly correlated to terrain parameters, crop yields, or a seasonal soil moisture index predicted from crop yields. SOC and 137Cs were weakly correlated (r2 ???0.2, F-test P-value 0.001), suggesting that soil transport controls, in part, SOC distribution. The study illustrates the importance of past site history when interpreting the landscape distribution of soil properties, especially those strongly influenced by human activity. Confounding variables, complex soil hydrology, and incomplete documentation of land use history make definitive interpretations of the processes behind the spatial distributions

  10. Host Life History Strategy, Species Diversity, and Habitat Influence Trypanosoma cruzi Vector Infection in Changing Landscapes

    PubMed Central

    Gottdenker, Nicole L.; Chaves, Luis Fernando; Calzada, José E.; Saldaña, Azael; Carroll, C. Ronald

    2012-01-01

    Background Anthropogenic land use may influence transmission of multi-host vector-borne pathogens by changing diversity, relative abundance, and community composition of reservoir hosts. These reservoir hosts may have varying competence for vector-borne pathogens depending on species-specific characteristics, such as life history strategy. The objective of this study is to evaluate how anthropogenic land use change influences blood meal species composition and the effects of changing blood meal species composition on the parasite infection rate of the Chagas disease vector Rhodnius pallescens in Panama. Methodology/Principal Findings R. pallescens vectors (N = 643) were collected in different habitat types across a gradient of anthropogenic disturbance. Blood meal species in DNA extracted from these vectors was identified in 243 (40.3%) vectors by amplification and sequencing of a vertebrate-specific fragment of the 12SrRNA gene, and T. cruzi vector infection was determined by pcr. Vector infection rate was significantly greater in deforested habitats as compared to contiguous forests. Forty-two different species of blood meal were identified in R. pallescens, and species composition of blood meals varied across habitat types. Mammals (88.3%) dominated R. pallescens blood meals. Xenarthrans (sloths and tamanduas) were the most frequently identified species in blood meals across all habitat types. A regression tree analysis indicated that blood meal species diversity, host life history strategy (measured as rmax, the maximum intrinsic rate of population increase), and habitat type (forest fragments and peridomiciliary sites) were important determinants of vector infection with T. cruzi. The mean intrinsic rate of increase and the skewness and variability of rmax were positively associated with higher vector infection rate at a site. Conclusions/Significance In this study, anthropogenic landscape disturbance increased vector infection with T. cruzi, potentially

  11. Factors influencing internal color of cooked meats.

    PubMed

    Suman, Surendranath P; Nair, Mahesh N; Joseph, Poulson; Hunt, Melvin C

    2016-10-01

    This manuscript overviews the pertinent research on internal color of uncured cooked meats, biochemical processes involved in meat cookery, and fundamental mechanisms governing myoglobin thermal stability. Heat-induced denaturation of myoglobin, responsible for the characteristic dull-brown color of cooked meats, is influenced by a multitude of endogenous (i.e., pH, muscle source, species, redox state) and exogenous (i.e., packaging, ingredients, storage) factors. The interactions between these factors critically influence the internal cooked color and can confuse the consumers, who often perceive cooked color to be a reliable indicator for doneness and safety. While certain phenomena in cooked meat color are cosmetic in nature, others can mislead consumers and result in foodborne illnesses. Research in meat color suggests that processing technologies and cooking practices in industry as well as households influence the internal cooked color. Additionally, the guidelines of many international public health and regulatory authorities recommend using meat thermometers to determine safe cooking endpoint temperature and to ensure product safety. PMID:27131513

  12. Factors influencing internal color of cooked meats.

    PubMed

    Suman, Surendranath P; Nair, Mahesh N; Joseph, Poulson; Hunt, Melvin C

    2016-10-01

    This manuscript overviews the pertinent research on internal color of uncured cooked meats, biochemical processes involved in meat cookery, and fundamental mechanisms governing myoglobin thermal stability. Heat-induced denaturation of myoglobin, responsible for the characteristic dull-brown color of cooked meats, is influenced by a multitude of endogenous (i.e., pH, muscle source, species, redox state) and exogenous (i.e., packaging, ingredients, storage) factors. The interactions between these factors critically influence the internal cooked color and can confuse the consumers, who often perceive cooked color to be a reliable indicator for doneness and safety. While certain phenomena in cooked meat color are cosmetic in nature, others can mislead consumers and result in foodborne illnesses. Research in meat color suggests that processing technologies and cooking practices in industry as well as households influence the internal cooked color. Additionally, the guidelines of many international public health and regulatory authorities recommend using meat thermometers to determine safe cooking endpoint temperature and to ensure product safety.

  13. Rationalizing three-dimensional activity landscapes and the influence of molecular representations on landscape topology and the formation of activity cliffs.

    PubMed

    Peltason, Lisa; Iyer, Preeti; Bajorath, Jürgen

    2010-06-28

    Activity landscapes are defined by potency and similarity distributions of active compounds and reflect the nature of structure-activity relationships (SARs). Three-dimensional (3D) activity landscapes are reminiscent of topographical maps and particularly intuitive representations of compound similarity and potency distributions. From their topologies, SAR characteristics can be deduced. Accordingly, idealized theoretical landscape models have been utilized to rationalize SAR features, but "true" 3D activity landscapes have not yet been described in detail. Herein we present a computational approach to derive approximate 3D activity landscapes for actual compound data sets and to analyze exemplary landscape representations. These activity landscapes are generated within a consistent reference frame so that they can be compared across different activity classes. We show that SAR features of compound data sets can be derived from the topology of landscape models. A notable correlation is observed between global SAR phenotypes, assigned on the basis of SAR discontinuity scoring, and characteristic landscape topologies. We also show that different molecular representations can substantially alter the topology of activity landscapes for a given data set and modulate the formation of activity cliffs, which represent the most prominent landscape features. Depending on the choice of molecular representations, compounds forming a steep activity cliff in a given landscape might be separated in another and no longer form a cliff. However, comparison of alternative activity landscapes makes it possible to focus on compound subsets having high SAR information content.

  14. Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia

    NASA Astrophysics Data System (ADS)

    Anderson, L. O.; Malhi, Y.; Ladle, R. J.; Aragão, L. E. O. C.; Shimabukuro, Y.; Phillips, O. L.; Baker, T.; Costa, A. C. L.; Espejo, J. S.; Higuchi, N.; Laurance, W. F.; López-González, G.; Monteagudo, A.; Núñez-Vargas, P.; Peacock, J.; Quesada, C. A.; Almeida, S.

    2009-09-01

    Long-term studies using the RAINFOR network of forest plots have generated significant insights into the spatial and temporal dynamics of forest carbon cycling in Amazonia. In this work, we map and explore the landscape context of several major RAINFOR plot clusters using Landsat ETM+ satellite data. In particular, we explore how representative the plots are of their landscape context, and test whether bias in plot location within landscapes may be influencing the regional mean values obtained for important forest biophysical parameters. Specifically, we evaluate whether the regional variations in wood productivity, wood specific density and above ground biomass derived from the RAINFOR network could be driven by systematic and unintentional biases in plot location. Remote sensing data covering 45 field plots were aggregated to generate landscape maps to identify the specific physiognomy of the plots. In the Landsat ETM+ data, it was possible to spectrally differentiate three types of terra firme forest, three types of forests over Paleovarzea geomorphologycal formation, two types of bamboo-dominated forest, palm forest, Heliconia monodominant vegetation, swamp forest, disturbed forests and land use areas. Overall, the plots were generally representative of the forest physiognomies in the landscape in which they are located. Furthermore, the analysis supports the observed regional trends in those important forest parameters. This study demonstrates the utility of landscape scale analysis of forest physiognomies for validating and supporting the finds of plot based studies. Moreover, the more precise geolocation of many key RAINFOR plot clusters achieved during this research provides important contextual information for studies employing the RAINFOR database.

  15. Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia

    NASA Astrophysics Data System (ADS)

    Anderson, L. O.; Malhi, Y.; Ladle, R. J.; Aragão, L. E. O. C.; Shimabukuro, Y.; Phillips, O. L.; Baker, T.; Costa, A. C. L.; Espejo, J. S.; Higuchi, N.; Laurance, W. F.; López-González, G.; Monteagudo, A.; Núñez-Vargas, P.; Peacock, J.; Quesada, C. A.; Almeida, S.; Vásquez, R.

    2009-02-01

    Long-term studies using the RAINFOR network of forest plots have generated significant insights into the spatial and temporal dynamics of forest carbon cycling in Amazonia. In this work, we map and explore the landscape context of several major RAINFOR plot clusters using Landsat ETM+ satellite data. In particular, we explore how representative the plots are of their landscape context, and test whether bias in plot location within landscapes may be influencing the regional mean values obtained for important forest biophysical parameters. Specifically, we evaluate whether the regional variations in wood productivity, wood specific density and above ground biomass derived from the RAINFOR network could be driven by systematic and unintentional biases in plot location. Remote sensing data covering 45 field plots were aggregated to generate landscape maps to identify the specific physiognomy of the plots. In the Landsat ETM+ data, it was possible to spectrally differentiate three types of terra firme forest, three types of alluvial terrain forest, two types of bamboo-dominated forest, palm forest, Heliconia monodominant vegetation, swamp forest, disturbed forests and land use areas. Overall, the plots were generally representative of the forest physiognomies in the landscape in which they are located. Furthermore, the analysis supports the observed regional trends in those important forest parameters. This study demonstrates the utility of landscape scale analysis of forest physiognomies for validating and supporting the finds of plot based studies. Moreover, the more precise geolocation of many key RAINFOR plot clusters achieved during this research provides important contextual information for studies employing the RAINFOR database.

  16. Spatial variation in fish assemblages across a beaver-influenced successional landscape

    USGS Publications Warehouse

    Schlosser, I.J.; Kallemeyn, L.W.

    2000-01-01

    Beavers are increasingly viewed as 'ecological engineers,' having broad effects on physical, chemical, and biological attributes of north-temperate landscapes. We examine the influence of both local successional processes associated with beaver activity and regional geomorphic boundaries on spatial variation in fish assemblages along the Kabetogama Peninsula in Voyageurs National Park, northern Minnesota, USA. Fish abundance and species richness exhibited considerable variation among drainages along the peninsula. Geological barriers to fish dispersal at outlets of some drainages has reduced fish abundance and species richness. Fish abundance and species richness also varied within drainages among local environments associated with beaver pond succession. Fish abundance was higher in upland ponds than in lowland ponds, collapsed ponds, or streams, whereas species richness was highest in collapsed ponds and streams. Cluster analyses based on fish abundance at sites classified according to successional environment indicated that four species (northern redbelly dace, Phoxinus eos; brook stickleback, Culaea inconstans; finescale dace, P. neogaeus; and fathead minnow, Pimephales promelas), were predominant in all successional environments. Several less abundant species were added in collapsed ponds and streams, with smaller size classes of large lake species (e.g., black crappie, Pomoxis nigromaculatus; smallmouth bass, Micropertus dolomieui; yellow perch, Perca flavescens; and burbot, Lota lota) being a component of these less abundant species. The addition of smaller size classes of large lake species indicates that dispersal of early life-history stages from Kabetogama Lake played a role in determining the species richness and composition of less abundant species in successional environments on the peninsula. Furthermore, collapsed-pond and stream environments closer to Kabetogama Lake had higher species richness than similar successional sites located farther from

  17. Multidisciplinary modeling and GIS for landscape management

    SciTech Connect

    Flamm, R.O.; Turner, M.G.

    1993-12-31

    Ecological dynamics in human-influenced landscapes are strongly affected by the socioeconomic factors that influence land-use decisions. Incorporating these factors into a spatially-explicit landscape-change model requires the integration of multidisciplinary data. We developed a model that simulates the effects of land use on landscape structure in the Little Tennessee River Basin in western North Carolina. This model uses a variety of data, including interpreted remotely-sensed imagery, census and ownership maps, topography, and results from econometric models. Data are integrated by using a geographic information system and translated into a common format, maps. Simulations generate new maps of land cover representing the amount of land-cover change that occurs. With spatially-explicit projections of landscape change, issues such as biodiversity conservation, the importance of specific landscape elements to conservation goals, and long-term landscape integrity can be addressed. In order for management to use the model to address these issues, a computer-based landscape-management decision aid is being developed. This tool integrates the models, associated data bases, and a geographic information system to facilitate the evaluation of land-use decisions and management plans. This system will estimate landscape-level consequences of alternative actions and will serve to focus coordination among different land-owners and land-use interests in managing the regional landscape.

  18. Staying cool in a changing landscape: the influence of maximum daily ambient temperature on grizzly bear habitat selection.

    PubMed

    Pigeon, Karine E; Cardinal, Etienne; Stenhouse, Gordon B; Côté, Steeve D

    2016-08-01

    To fulfill their needs, animals are constantly making trade-offs among limiting factors. Although there is growing evidence about the impact of ambient temperature on habitat selection in mammals, the role of environmental conditions and thermoregulation on apex predators is poorly understood. Our objective was to investigate the influence of ambient temperature on habitat selection patterns of grizzly bears in the managed landscape of Alberta, Canada. Grizzly bear habitat selection followed a daily and seasonal pattern that was influenced by ambient temperature, with adult males showing stronger responses than females to warm temperatures. Cutblocks aged 0-20 years provided an abundance of forage but were on average 6 °C warmer than mature conifer stands and 21- to 40-year-old cutblocks. When ambient temperatures increased, the relative change (odds ratio) in the probability of selection for 0- to 20-year-old cutblocks decreased during the hottest part of the day and increased during cooler periods, especially for males. Concurrently, the probability of selection for 21- to 40-year-old cutblocks increased on warmer days. Following plant phenology, the odds of selecting 0- to 20-year-old cutblocks also increased from early to late summer while the odds of selecting 21- to 40-year-old cutblocks decreased. Our results demonstrate that ambient temperatures, and therefore thermal requirements, play a significant role in habitat selection patterns and behaviour of grizzly bears. In a changing climate, large mammals may increasingly need to adjust spatial and temporal selection patterns in response to thermal constraints.

  19. Staying cool in a changing landscape: the influence of maximum daily ambient temperature on grizzly bear habitat selection.

    PubMed

    Pigeon, Karine E; Cardinal, Etienne; Stenhouse, Gordon B; Côté, Steeve D

    2016-08-01

    To fulfill their needs, animals are constantly making trade-offs among limiting factors. Although there is growing evidence about the impact of ambient temperature on habitat selection in mammals, the role of environmental conditions and thermoregulation on apex predators is poorly understood. Our objective was to investigate the influence of ambient temperature on habitat selection patterns of grizzly bears in the managed landscape of Alberta, Canada. Grizzly bear habitat selection followed a daily and seasonal pattern that was influenced by ambient temperature, with adult males showing stronger responses than females to warm temperatures. Cutblocks aged 0-20 years provided an abundance of forage but were on average 6 °C warmer than mature conifer stands and 21- to 40-year-old cutblocks. When ambient temperatures increased, the relative change (odds ratio) in the probability of selection for 0- to 20-year-old cutblocks decreased during the hottest part of the day and increased during cooler periods, especially for males. Concurrently, the probability of selection for 21- to 40-year-old cutblocks increased on warmer days. Following plant phenology, the odds of selecting 0- to 20-year-old cutblocks also increased from early to late summer while the odds of selecting 21- to 40-year-old cutblocks decreased. Our results demonstrate that ambient temperatures, and therefore thermal requirements, play a significant role in habitat selection patterns and behaviour of grizzly bears. In a changing climate, large mammals may increasingly need to adjust spatial and temporal selection patterns in response to thermal constraints. PMID:27085998

  20. Neonatal thyroid function: influence of perinatal factors.

    PubMed Central

    Franklin, R C; Carpenter, L M; O'Grady, C M

    1985-01-01

    Indices of thyroid function were measured in 229 healthy term neonates at birth and at 5, 10, and 15 days of age. Results were analysed to assess whether maternal diabetes mellitus, toxaemia of pregnancy, intrapartum fetal distress, duration of labour, method of delivery, asphyxia at birth, race, sex, birthweight, birth length, head circumference, or method of feeding influenced any index. Thyroxine, the free thyroxine index, and free thyroxine concentrations at birth correlated with birthweight. Method of delivery influenced mean thyroxine and free thyroxine index values at birth and at age 5 days. Mean values of triiodothyronine, reverse triiodothyronine, thyroxine binding globulin, and thyroid stimulating hormone were not affected by any of the perinatal factors studied. Birthweight and perhaps method of delivery should be taken into account when interpreting neonatal thyroxine parameters but determination of thyroid stimulating hormone as a screen for congenital hypothyroidism in healthy term neonates circumvents these considerations. PMID:3977386

  1. Factors influencing participation in breast cancer screening.

    PubMed

    Edgar, Lynne; Glackin, Marie; Hughes, Caroline; Rogers, Katherine Mary Ann

    Despite the efficacy of mammography and the widespread promotion of screening programmes, a significant number of eligible women still do not attend for regular breast screening. An integrative review methodology was considered the most appropriate means to critically analyse the available literature pertaining to factors which influence participation in breast cancer screening. From the extensive literature search, 12 selected core research papers met the inclusion criteria and were incorporated in the literature review. Four themes emerged from the literature which impact on participation in mammography screening: psychological and practical issues, ethnicity issues, influence of socioeconomic status and issues related to screening programmes. The recent Independent Review Panel on Breast Cancer Screening endorsed the importance of access to information which clearly communicates the harms and benefits of breast screening to enable women to make informed decisions about their health. The recommendations from the panel and others have been included in this review. PMID:24067312

  2. Factors influencing aircraft ground handling performance

    NASA Technical Reports Server (NTRS)

    Yager, T. J.

    1983-01-01

    Problems associated with aircraft ground handling operations on wet runways are discussed and major factors which influence tire/runway braking and cornering traction capability are identified including runway characteristics, tire hydroplaning, brake system anomalies, and pilot inputs. Research results from tests with instrumented ground vehicles and aircraft, and aircraft wet runway accident investigation are summarized to indicate the effects of different aircraft, tire, and runway parameters. Several promising means are described for improving tire/runway water drainage capability, brake system efficiency, and pilot training to help optimize aircraft traction performance on wet runways.

  3. [Influence of weather factors on suicidal hangings].

    PubMed

    Trepińska, Janina; Piotrowicz, Katarzyna; Bakowski, Rafał; Bolechała, Filip; Trela, Franciszek

    2005-01-01

    The paper presents a certain biometeorological problem. The evaluation of influence of weather factors on frequency of suicidal cases by hanging in the area of Cracow City during 1991-2002 was examined. Rapid changes of air pressure, air temperature, hot, sweltering and sultry days, very frosty days, days with strong or foehn wind, days with thunderstorms, fog and haze were selected as unfavourable weather factors. They give an occasion for strong psychical stress. The results of detailed investigations are next: more frequency of cases of suicide during the advance of cold fronts, rapid decreases of air pressure during hot, sweltering and sultry days, days with thunderstorms and foehn winds in the Tatra Mountains. PMID:16521499

  4. Factors influencing global antiretroviral procurement prices

    PubMed Central

    2009-01-01

    Background Antiretroviral medicines (ARVs) are one of the most costly parts of HIV/AIDS treatment. Many countries are struggling to provide universal access to ARVs for all people living with HIV and AIDS. Although substantial price reductions of ARVs have occurred, especially between 2002 and 2008, achieving sustainable access for the next several decades remains a major challenge for most low- and middle-income countries. The objectives of the present study were twofold: first, to analyze global ARV prices between 2005 and 2008 and associated factors, particularly procurement methods and key donor policies on ARV procurement efficiency; second, to discuss the options of procurement processes and policies that should be considered when implementing or reforming access to ARV programs. Methods An ARV-medicines price-analysis was carried out using the Global Price Reporting Mechanism from the World Health Organization. For a selection of 12 ARVs, global median prices and price variation were calculated. Linear regression models for each ARV were used to identify factors that were associated with lower procurement prices. Logistic regression models were used to identify the characteristics of those countries which procure below the highest and lowest direct manufactured costs. Results Three key factors appear to have an influence on a country's ARV prices: (a) whether the product is generic or not; (b) the socioeconomic status of the country; (c) whether the country is a member of the Clinton HIV/AIDS Initiative. Factors which did not influence procurement below the highest direct manufactured costs were HIV prevalence, procurement volume, whether the country belongs to the least developed countries or a focus country of the United States President's Emergency Plan For AIDS Relief. Conclusion One of the principal mechanisms that can help to lower prices for ARV over the next several decades is increasing procurement efficiency. Benchmarking prices could be one useful

  5. Landscape epidemiology of plant diseases.

    PubMed

    Plantegenest, Manuel; Le May, Christophe; Fabre, Frédéric

    2007-10-22

    Many agricultural landscapes are characterized by a high degree of heterogeneity and fragmentation. Landscape ecology focuses on the influence of habitat heterogeneity in space and time on ecological processes. Landscape epidemiology aims at applying concepts and approaches originating from landscape ecology to the study of pathogen dynamics at the landscape scale. However, despite the strong influence that the landscape properties may have on the spread of plant diseases, landscape epidemiology has still received little attention from plant pathologists. Some recent methodological and technological progress provides new and powerful tools to describe and analyse the spatial patterns of host-pathogen interactions. Here, we review some important topics in plant pathology that may benefit from a landscape perspective. These include the influence of: landscape composition on the global inoculum pressure; landscape heterogeneity on pathogen dynamics; landscape structure on pathogen dispersal; and landscape properties on the emergence of pathogens and on their evolution.

  6. RESEARCH PLAN: LANDSCAPE AND WATERSHED INFLUENCES ON WILD SALMON AND FISH ASSEMBLAGES IN OREGON COASTAL STREAMS

    EPA Science Inventory

    This document is a Research Plan. In the Pacific Northwest (PNW), many populations of wild anadromous salmonids are in serious decline. Landscape change, water pollution, introduced predators, fishing, hydropower development, hatcheries, disadvantageous ocean conditions, and ot...

  7. Nutrient mitigation efficiency in agricultural drainage ditches: An influence of landscape properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drainage systems are integral parts of the agricultural landscapes and have the ability to intercept nutrient loading from runoff to surface water. This study investigated nutrient removal efficiency within replicated experimental conventional and controlled (with weirs) agricultural drainage ditche...

  8. Environmental factors influencing community composition of gastropods and their trematode parasites in southern Ontario.

    PubMed

    Koprivnikar, Janet; Baker, Robert L; Forbes, Mark R

    2007-10-01

    Agricultural activity and landscape features have previously been associated with diversity and prevalence of trematode species in amphibian second intermediate hosts. In this study, the density, diversity, and size of snail first intermediate hosts, and the diversity and prevalence of their trematode species, were assessed in 2 types of ponds, i.e., those adjacent to cornfields and those from the same region in southwestern Ontario that were adjacent to nonagricultural settings. Species of trematodes included, but were not restricted to, those that are known parasites of larval and adult frogs. We also assessed landscape factors likely to influence use by definitive hosts. Presence of the herbicide atrazine in ponds was measured to check that ponds adjacent to agriculture had potential to be affected by agricultural runoff. Both snail size and the proportion of snails releasing cercariae were greater in nonagricultural ponds, contrasting with a previous finding of lower trematode infection in tadpoles from nonagricultural ponds. Percentage of forest cover was associated with prevalence of certain trematode species, but not with estimates of combined prevalence. Absence of relations of trematode prevalence to measures of road density also contrasted with previous studies. We interpret our results in light of how agricultural activity might influence trematode viability, snail growth, and use by wildlife definitive hosts, independently of landscape factors.

  9. Factors that influence engagement in collaborative practice

    PubMed Central

    Herbert, Carol P.; Bainbridge, Lesley; Bickford, Julia; Baptiste, Susan; Brajtman, Susan; Dryden, Trish; Hall, Pippa; Risdon, Cathy; Solomon, Patricia

    2007-01-01

    OBJECTIVE To generate hypotheses regarding factors that might influence engagement in collaborative practice. DESIGN Qualitative study using in-depth interviews. SETTING Participants interviewed each other in dyads. The pairing was based upon geographical location and proximity to each other. PARTICIPANTS Eight professionals from the disciplines of medicine, nursing, occupational therapy, physical therapy, and massage therapy. METHOD Semistructured interviews, lasting 30 to 45 minutes each, were recorded and transcribed verbatim. The transcripts were read by all research team members using independent content analysis for common words, phrases, statements, or units of text for key themes. At a subsequent face-to-face meeting, the team used an iterative process of comparing and contrasting key themes until consensus was reached. The transcripts were then analyzed further for subthemes using NVivo software. MAIN FINDINGS Initial findings suggest that some common characteristics grounded in family history, school experiences, social interactions, and professional training might influence collaborative practice choices. The narrative form of the interview broke down interpersonal and interprofessional barriers, creating a new level of trust and respect that could improve professional collaboration. CONCLUSION This study suggests that life experiences from childhood into later adulthood can and do influence professional choices. PMID:17872847

  10. Climate influence on volcano edifice stability and fluvial landscape evolution surrounding Mount Ruapehu, New Zealand

    NASA Astrophysics Data System (ADS)

    Tost, M.; Cronin, S. J.

    2016-06-01

    Large volcanic debris avalanches are triggered by failure of the steep flanks of long-lived composite cones. Their huge deposits change the landscape and drainage pattern surrounding stratovolcanoes for thousands of years. At Mt. Ruapehu, New Zealand, we identified seven major flank-collapse events that produced debris avalanches travelling down pre-existing river catchments for up to 90 km from source. In two cases the extreme mass flux into the river valleys led to their complete truncation from the volcano, while four drainage systems were subsequently re-established along similar pathways influenced by regional strike-slip faulting, which caused localized graben formation. In all cases the volcanic debris-avalanche deposits currently form distinctive plateaus at or near the highest topographic elevations of each river valley margin. The timing of the flank failures indicate that inter-eruptive cone destabilization of Mt. Ruapehu is affected by climate change and occurs most commonly during interstadials when glaciers on the cone are in retreat, whereas syn-eruptive collapses are most prominent during cold stages. Dated debris-avalanche deposit levels, along with those of up to four stadial-related aggradational gravel terraces between c. 125 and 18 ka, were used to calculate regional uplift rates in this area. Rates of between 0.2 ± 0.1 mm yr- 1 to 3.8 ± 0.8 mm yr- 1 are found for four river systems dissecting the central North Island of New Zealand. In three cases incision below the diamicton sequences and into the basement, allowed quantification of sediment-flux rates into the Tasman Sea of 107,000 ± 1,200 m3 yr- 1 to 177,000 ± 3,500 m3 yr- 1 since debris-avalanche emplacement.

  11. Cracking the Critical Zone: How trees grow their own pot and influence landscape evolution

    NASA Astrophysics Data System (ADS)

    Marshall, Jill

    2016-04-01

    Quantifying linkages between climate, ecosystems, lithology, soil production and erosion rates is one of the grand challenges for understanding influences on the Critical Zone and landscape evolution through time. Hydrologic routing, net primary productivity, carbon storage in soils, and mineral supplies for the geochemical reactor are all linked to rates of soil production. While trees serve as soil stabilizers over short time scales, over longer time scales, trees can damage, disrupt and detach bedrock in thin to no soil settings. In this sense, trees can grow their own soil pots. The pace of tree-driven soil production may set the pace of erosion into the underlying parent material. Root growth and tree throw then prime the mobile material for downslope transport. However - do tree roots actually create fractures, expand fractures, or merely exploit existing fractures in competent bedrock or saprolite? At present, this question looms large in the earth sciences while complicated by a paucity of available data and methods to measure root forces at the bedrock-root interface. Here I present evidence suggesting that bedrock detachment is a function of the interplay among rock strength, fracture density, root and tree size, and root density with depth. I propose that depth-dependent soil production rates are controlled by both the frequency and magnitude of multiple physical mechanisms that likely weaken and detach rock including tree sway, tree throw, root growth forces, root wedging and diurnal fluctuations due to water uptake all modulated by rock properties. I present preliminary data from a novel technique that measures forces at the rock-root interface that I will use to parameterize a biomechanical soil production function.

  12. Factors affecting songbird nest survival in riparian forests in a midwestern agricultural landscape

    USGS Publications Warehouse

    Peak, R.G.; Thompson, F. R.; Shaffer, T.L.

    2004-01-01

    We investigated factors affecting nest success of songbirds in riparian forest and buffers in northeastern Missouri. We used an information-theoretic approach to determine support for hypotheses concerning effects of nest-site, habitat-patch, edge, and temporal factors on nest success of songbirds in three narrow (55-95 m) and three wide (400-530 m) riparian forests with adjacent grassland-shrub buffer strips and in three narrow and three wide riparian forests without adjacent grassland-shrub buffer strips. We predicted that temporal effects would have the most support and that habitat-patch and edge effects would have little support, because nest predation would be great across all sites in the highly fragmented, predominantly agricultural landscape. Interval nest success was 0.404, 0.227, 0.070, and 0.186, respectively, for Gray Catbird (Dumetella carolinensis), Northern Cardinal (Cardinalis cardinalis), Indigo Bunting (Passerina cyanea), and forest interior species pooled (Acadian Flycatcher [Empidonax virescens], Wood Thrush [Hylocichla mustelina], Ovenbird [Seiurus aurocapillus], and Kentucky Warbler [Oporornis formosus]). The effect of nest stage on nest success had the most support; daily nest success for Gray Catbird and Indigo Bunting were lowest in the laying stage. We found strong support for greater nest success of Gray Catbird in riparian forests with adjacent buffer strips than in riparian forests without adjacent buffer strips. Patch width also occurred in the most-supported model for Gray Catbird, but with very limited support. The null model received the most support for Northern Cardinal. Riparian forests provided breeding habitat for area-sensitive forest species and grassland-shrub nesting species. Buffer strips provided additional breeding habitat for grassland-shrub nesting species. Interval nest success for Indigo Bunting and area-sensitive forest species pooled, however, fell well below the level that is likely necessary to balance juvenile

  13. Factors affecting songbird nest survival in riparian forests in a Midwestern agricultural landscape

    USGS Publications Warehouse

    Peak, R.G.; Thompson, F. R.; Shaffer, T.L.

    2004-01-01

    We investigated factors affecting nest success of songbirds in riparian forest and buffers in northeastern Missouri. We used an information-theoretic approach to determine support for hypotheses concerning effects of nest-site, habitat-patch, edge, and temporal factors on nest success of songbirds in three narrow (55DS95 m) and three wide (400DS530 m) riparian forests with adjacent grasslandDSshrub buffer strips and in three narrow and three wide riparian forests without adjacent grasslandDSshrub buffer strips. We predicted that temporal effects would have the most support and that habitat-patch and edge effects would have little support, because nest predation would be great across all sites in the highly fragmented, predominantly agricultural landscape. Interval nest success was 0.404, 0.227, 0.070, and 0.186, respectively, for Gray Catbird (Dumetella carolinensis), Northern Cardinal (Cardinalis cardinalis), Indigo Bunting (Passerina cyanea), and forest interior species pooled (Acadian Flycatcher [Empidonax virescens], Wood Thrush [Hylocichla mustelina], Ovenbird [Seiurus aurocapillus], and Kentucky Warbler [Oporornis formosus]). The effect of nest stage on nest success had the most support; daily nest success for Gray Catbird and Indigo Bunting were lowest in the laying stage. We found strong support for greater nest success of Gray Catbird in riparian forests with adjacent buffer strips than in riparian forests without adjacent buffer strips. Patch width also occurred in the most supported model for Gray Catbird, but with very limited support. The null model received the most support for Northern Cardinal. Riparian forests provided breeding habitat for areas sensitive forest species and grassland-shrub nesting species. Buffer strips provided additional breeding habitat for grassland-shrub nesting species. Interval nest success for Indigo Bunting and area-sensitive forest species pooled, however, fell well below the level that is likely necessary to balance

  14. Factors influencing decisions on seclusion and restraint.

    PubMed

    Larue, C; Dumais, A; Ahern, E; Bernheim, E; Mailhot, M-P

    2009-06-01

    Seclusion with or without restraint is a measure for managing aggressive or agitated clients and promoting site security, particularly in an emergency psychiatric setting. The decision to control a potentially dangerous person's behaviour by removal or seclusion seems ethically justifiable in such a setting. However, although the decisions on these restrictive measures are based on rational needs, they are also influenced by the healthcare team's perceptions of the client and by the characteristics of the team and the environment. The purpose of this paper is to set out and categorize the factors in play in aggression- and agitation-management situations as perceived by the healthcare teams, particularly the nurses. The first part of the paper deals briefly with the settings in which control measures are applied in a province in eastern Canada and the effect of such measures on patients and healthcare teams. The second part identifies the factors involved in the management of agitation and aggression behaviour. The final part discusses the current spin-offs from this knowledge as well as promising paths for further research on the factors involved. The ultimate objective is to reduce recourse to coercive measures and enhance professional practices.

  15. Factors influencing decisions on seclusion and restraint.

    PubMed

    Larue, C; Dumais, A; Ahern, E; Bernheim, E; Mailhot, M-P

    2009-06-01

    Seclusion with or without restraint is a measure for managing aggressive or agitated clients and promoting site security, particularly in an emergency psychiatric setting. The decision to control a potentially dangerous person's behaviour by removal or seclusion seems ethically justifiable in such a setting. However, although the decisions on these restrictive measures are based on rational needs, they are also influenced by the healthcare team's perceptions of the client and by the characteristics of the team and the environment. The purpose of this paper is to set out and categorize the factors in play in aggression- and agitation-management situations as perceived by the healthcare teams, particularly the nurses. The first part of the paper deals briefly with the settings in which control measures are applied in a province in eastern Canada and the effect of such measures on patients and healthcare teams. The second part identifies the factors involved in the management of agitation and aggression behaviour. The final part discusses the current spin-offs from this knowledge as well as promising paths for further research on the factors involved. The ultimate objective is to reduce recourse to coercive measures and enhance professional practices. PMID:19538600

  16. Factors influencing BMI classifications of Korean adults.

    PubMed

    Chang, Ae Kyung; Choi, Jin Yi

    2015-05-01

    [Purpose] This study aimed to identify factors influencing the BMI classifications of 3,583 Korean adults using data from the fifth Korean National Health and Nutrition Examination Survey. [Subjects and Methods] Measures included lifestyle factors, physiologic factors, perceived health state, stress, subjective body recognition, health-related quality of life, and weight control behavior. [Results] Body perception scores were lower with underweight and higher with overweight and obesity than with a healthy weight. There was a lower proportion of underweight men and a higher proportion of overweight or obese men than women. Instances of Alcohol Use Identification Scores (AUDIT) ≥ 9 were proportionately lower with underweight and more with overweight or obesity relative to an AUDIT score < 9 with healthy weight. Hemoglobin A1c and systolic blood pressure were higher with obesity than with healthy weight. The total cholesterol level was greater with overweight and obesity than with healthy weight. [Conclusion] These results suggest that obesity intervention for adults should be based on age and sex and should include drinking habits and physical activity.

  17. Influence of habitat complexity and landscape configuration on pollination and seed-dispersal interactions of wild cherry trees.

    PubMed

    Breitbach, Nils; Tillmann, Svenja; Schleuning, Matthias; Grünewald, Claudia; Laube, Irina; Steffan-Dewenter, Ingolf; Böhning-Gaese, Katrin

    2012-02-01

    Land-use intensification is a major cause for the decline in species diversity in human-modified landscapes. The loss of functionally important species can reduce a variety of ecosystem functions, such as pollination and seed dispersal, but the intricate relationships between land-use intensity, biodiversity and ecosystem functioning are still contentious. Along a gradient from forest to intensively used farmland, we quantified bee species richness, visitation rates of bees and pollination success of wild cherry trees (Prunus avium). We analysed the effects of structural habitat diversity at a local scale and of the proportion of suitable habitat around each tree at a landscape scale. We compared these findings with those from previous studies of seed-dispersing birds and mammals in the same model system and along the same land-use gradient. Bee species richness and visitation rates were found to be highest in structurally simple habitats, whereas bird species richness--but not their visitation rates--were highest in structurally complex habitats. Mammal visitation rates were only influenced at the landscape scale. These results show that different functional groups of animals respond idiosyncratically to gradients in habitat and landscape structure. Despite strong effects on bees and birds, pollination success and bird seed removal did not differ along the land-use gradient at both spatial scales. These results suggest that mobile organisms, such as bees and birds, move over long distances in intensively used landscapes and thereby buffer pollination and seed-dispersal interactions. We conclude that measures of species richness and interaction frequencies are not sufficient on their own to understand the ultimate consequences of land-use intensification on ecosystem functioning. PMID:21818655

  18. Applying landscape genetics to the microbial world.

    PubMed

    Dudaniec, Rachael Y; Tesson, Sylvie V M

    2016-07-01

    Landscape genetics, which explicitly quantifies landscape effects on gene flow and adaptation, has largely focused on macroorganisms, with little attention given to microorganisms. This is despite overwhelming evidence that microorganisms exhibit spatial genetic structuring in relation to environmental variables. The increasing accessibility of genomic data has opened up the opportunity for landscape genetics to embrace the world of microorganisms, which may be thought of as 'the invisible regulators' of the macroecological world. Recent developments in bioinformatics and increased data accessibility have accelerated our ability to identify microbial taxa and characterize their genetic diversity. However, the influence of the landscape matrix and dynamic environmental factors on microorganism genetic dispersal and adaptation has been little explored. Also, because many microorganisms coinhabit or codisperse with macroorganisms, landscape genomic approaches may improve insights into how micro- and macroorganisms reciprocally interact to create spatial genetic structure. Conducting landscape genetic analyses on microorganisms requires that we accommodate shifts in spatial and temporal scales, presenting new conceptual and methodological challenges not yet explored in 'macro'-landscape genetics. We argue that there is much value to be gained for microbial ecologists from embracing landscape genetic approaches. We provide a case for integrating landscape genetic methods into microecological studies and discuss specific considerations associated with the novel challenges this brings. We anticipate that microorganism landscape genetic studies will provide new insights into both micro- and macroecological processes and expand our knowledge of species' distributions, adaptive mechanisms and species' interactions in changing environments.

  19. Landscape Fragmentation as a Risk Factor for Buruli Ulcer Disease in Ghana.

    PubMed

    Wu, Jianyong; Smithwick, Erica A H

    2016-07-01

    Land cover and its change have been linked to Buruli ulcer (BU), a rapidly emerging tropical disease. However, it is unknown whether landscape structure affects the disease prevalence. To examine the association between landscape pattern and BU presence, we obtained land cover information for 20 villages in southwestern Ghana from high resolution satellite images, and analyzed the landscape pattern surrounding each village. Eight landscape metrics indicated that landscape patterns between BU case and reference villages were different (P < 0.05) at the broad spatial extent examined (4 km). The logistic regression models showed that landscape fragmentation and diversity indices were positively associated with BU presence in a village. Specifically, for each increase in patch density and edge density by 100 units, the likelihood of BU presence in a village increased 2.51 (95% confidence interval [CI] = 1.36-4.61) and 4.18 (95% CI = 1.63-10.76) times, respectively. The results suggest that increased landscape fragmentation may pose a risk to the emergence of BU.

  20. Structural Landscape of the Proline-Rich Domain of Sos1 Nucleotide Exchange Factor

    PubMed Central

    McDonald, Caleb B.; Bhat, Vikas; Kurouski, Dmitry; Mikles, David C.; Deegan, Brian J.; Seldeen, Kenneth L.; Lednev, Igor K.; Farooq, Amjad

    2013-01-01

    Despite its key role in mediating a plethora of cellular signaling cascades pertinent to health and disease, little is known about the structural landscape of the proline-rich (PR) domain of Sos1 guanine nucleotide exchange factor. Herein, using a battery of biophysical tools, we provide evidence that the PR domain of Sos1 is structurally disordered and adopts an extended random coil-like conformation in solution. Of particular interest is the observation that while chemical denaturation of PR domain results in the formation of a significant amount of polyproline II (PPII) helices, it has little or negligible effect on its overall size as measured by its hydrodynamic radius. Our data also show that the PR domain displays a highly dynamic conformational basin in agreement with the knowledge that the intrinsically unstructured proteins rapidly interconvert between an ensemble of conformations. Collectively, our study provides new insights into the conformational equilibrium of a key signaling molecule with important consequences on its physiological function. PMID:23528987

  1. Structural landscape of the proline-rich domain of Sos1 nucleotide exchange factor.

    PubMed

    McDonald, Caleb B; Bhat, Vikas; Kurouski, Dmitry; Mikles, David C; Deegan, Brian J; Seldeen, Kenneth L; Lednev, Igor K; Farooq, Amjad

    2013-01-01

    Despite its key role in mediating a plethora of cellular signaling cascades pertinent to health and disease, little is known about the structural landscape of the proline-rich (PR) domain of Sos1 guanine nucleotide exchange factor. Herein, using a battery of biophysical tools, we provide evidence that the PR domain of Sos1 is structurally disordered and adopts an extended random coil-like conformation in solution. Of particular interest is the observation that while chemical denaturation of PR domain results in the formation of a significant amount of polyproline II (PPII) helices, it has little or negligible effect on its overall size as measured by its hydrodynamic radius. Our data also show that the PR domain displays a highly dynamic conformational basin in agreement with the knowledge that the intrinsically unstructured proteins rapidly interconvert between an ensemble of conformations. Collectively, our study provides new insights into the conformational equilibrium of a key signaling molecule with important consequences on its physiological function. PMID:23528987

  2. Landscape and Meteorological Factors Affecting Prevalence of Three Food-Borne Pathogens in Fruit and Vegetable Farms

    PubMed Central

    Strawn, Laura K.; Fortes, Esther D.; Bihn, Elizabeth A.; Nightingale, Kendra K.; Gröhn, Yrjö T.; Worobo, Randy W.; Wiedmann, Martin

    2013-01-01

    Produce-related outbreaks have been traced back to the preharvest environment. A longitudinal study was conducted on five farms in New York State to characterize the prevalence, persistence, and diversity of food-borne pathogens in fresh produce fields and to determine landscape and meteorological factors that predict their presence. Produce fields were sampled four times per year for 2 years. A total of 588 samples were analyzed for Listeria monocytogenes, Salmonella, and Shiga toxin-producing Escherichia coli (STEC). The prevalence measures of L. monocytogenes, Salmonella, and STEC were 15.0, 4.6, and 2.7%, respectively. L. monocytogenes and Salmonella were detected more frequently in water samples, while STEC was detected with equal frequency across all sample types (soil, water, feces, and drag swabs). L. monocytogenes sigB gene allelic types 57, 58, and 61 and Salmonella enterica serovar Cerro were repeatedly isolated from water samples. Soil available water storage (AWS), temperature, and proximity to three land cover classes (water, roads and urban development, and pasture/hay grass) influenced the likelihood of detecting L. monocytogenes. Drainage class, AWS, and precipitation were identified as important factors in Salmonella detection. This information was used in a geographic information system framework to hypothesize locations of environmental reservoirs where the prevalence of food-borne pathogens may be elevated. The map indicated that not all croplands are equally likely to contain environmental reservoirs of L. monocytogenes. These findings advance recommendations to minimize the risk of preharvest contamination by enhancing models of the environmental constraints on the survival and persistence of food-borne pathogens in fields. PMID:23144137

  3. Factors that can influence mentorship relationships.

    PubMed

    Hodges, Beverly

    2009-07-01

    Mentorship is an integral part of the qualified nurse role that supports learning and development. The quality of the relationship between mentor and mentee can affect learning, particularly any disparity in their expectations. A fictitious scenario is used in this article to highlight the effect of different perceptions of the mentorship relationship, with a particular focus on the nursing student and qualified nurse. Factors that can have a negative influence on mentoring include poor communication, differing expectations between mentor and mentee, lack of trust and lack of appreciation of everyday life circumstances that affects each person. The use of learning contracts, formulation of ground rules, use of information in student handbooks and discussion of the expectations of the mentor and mentee can help prevent or counteract problems in the relationship. PMID:19623801

  4. Factors influencing acrylamide formation in gingerbread.

    PubMed

    Amrein, Thomas M; Schönbächler, Barbara; Escher, Felix; Amadò, Renato

    2005-01-01

    The influence of ingredients, additives, and process conditions on the acrylamide formation in gingerbread was investigated. The sources for reducing sugars and free asparagine were identified and the effect of different baking agents on the acrylamide formation was evaluated. Ammonium hydrogencarbonate strongly enhanced the acrylamide formation, but its N-atom was not incorporated into acrylamide, nor did acrylic acid form acrylamide in gingerbread. Acrylamide concentration and browning intensity increased both with baking time and correlated with each other. The use of sodium hydrogencarbonate as baking agent reduced the acrylamide concentration by more than 60%. Free asparagine was a limiting factor for acrylamide formation, but the acrylamide content could also be lowered by replacing reducing sugars with sucrose or by adding moderate amounts of organic acids. A significant reduction of the acrylamide content in gingerbread can be achieved by using sodium hydrogencarbonate as baking agent, minimizing free asparagine, and avoiding prolonged baking.

  5. Factors influencing presence in virtual worlds.

    PubMed

    Chow, Meyrick C M

    2012-01-01

    Virtual worlds are showing potential as an effective platform for a variety of activities, including learning. The concept of presence (the sensation of "being there" in a mediated environment) has received substantial attention from the virtual reality community, and the effectiveness of virtual worlds has often been linked to the feelings of presence reported by their users. The present study examined the effects of attitude and perceived ease of use on sense of presence in Second Life, which is one of the most known and used virtual worlds. Based on data from a survey of 206 nursing students, hypotheses are empirically tested. Findings suggest that users' attitude toward using Second Life and their perceived ease of use of it have a positive effect on their sense of presence in the virtual environment. This study advances our understanding of factors influencing presence in virtual worlds.

  6. Factors influencing presence in virtual worlds

    PubMed Central

    Chow, Meyrick C.M.

    2012-01-01

    Virtual worlds are showing potential as an effective platform for a variety of activities, including learning. The concept of presence (the sensation of “being there” in a mediated environment) has received substantial attention from the virtual reality community, and the effectiveness of virtual worlds has often been linked to the feelings of presence reported by their users. The present study examined the effects of attitude and perceived ease of use on sense of presence in Second Life, which is one of the most known and used virtual worlds. Based on data from a survey of 206 nursing students, hypotheses are empirically tested. Findings suggest that users’ attitude toward using Second Life and their perceived ease of use of it have a positive effect on their sense of presence in the virtual environment. This study advances our understanding of factors influencing presence in virtual worlds. PMID:24199058

  7. Modeling fluvial incision and transient landscape evolution: Influence of dynamic channel adjustment

    NASA Astrophysics Data System (ADS)

    Attal, M.; Tucker, G. E.; Whittaker, A. C.; Cowie, P. A.; Roberts, G. P.

    2008-09-01

    Channel geometry exerts a fundamental control on fluvial processes. Recent work has shown that bedrock channel width depends on a number of parameters, including channel slope, and is not solely a function of drainage area as is commonly assumed. The present work represents the first attempt to investigate the consequences of dynamic, gradient-sensitive channel adjustment for drainage-basin evolution. We use the Channel-Hillslope Integrated Landscape Development (CHILD) model to analyze the response of a catchment to a given tectonic perturbation, using, as a template, the topography of a well-documented catchment in the footwall of an active normal fault in the Apennines (Italy) that is known to be undergoing a transient response to tectonic forcing. We show that the observed transient response can be reproduced to first order with a simple detachment-limited fluvial incision law. Transient landscape is characterized by gentler gradients and a shorter response time when dynamic channel adjustment is allowed. The differences in predicted channel geometry between the static case (width dependent solely on upstream area) and dynamic case (width dependent on both drainage area and channel slope) lead to contrasting landscape morphologies when integrated at the scale of a whole catchment, particularly in presence of strong tilting and/or pronounced slip-rate acceleration. Our results emphasize the importance of channel width in controlling fluvial processes and landscape evolution. They stress the need for using a dynamic hydraulic scaling law when modeling landscape evolution, particularly when the relative uplift field is nonuniform.

  8. Landscape influences on aluminium and dissolved organic carbon in streams draining the Hubbard Brook valley, New Hampshire, USA

    NASA Astrophysics Data System (ADS)

    Palmer, Sheila M.; Wellington, Brian I.; Johnson, Chris E.; Driscoll, Charles T.

    2005-06-01

    Concentrations of both aluminium (Al) and dissolved organic carbon (DOC) in stream waters are likely to be regulated by factors that influence water flowpaths and residence times, and by the nature of the soil horizons through which waters flow. In order to investigate landscape-scale spatial patterns in streamwater Al and DOC, we sampled seven streams draining the Hubbard Brook valley in central New Hampshire. We observed considerable variation in stream chemistry both within and between headwater watersheds. Across the valley, concentrations of total monomeric aluminium (Alm) ranged from below detection limits (<0.7 μmol l-1) to 22.3 μmol l-1. In general, concentrations of Alm decreased as pH increased downslope. There was a strong relationship between organic monomeric aluminium (Alo) and DOC concentrations (R2 = 0.92).We observed the highest Alm concentrations in: (i) a watershed characterized by a steep narrow drainage basin and shallow soils and (ii) a watershed characterized by exceptionally deep forest floor soils and high concentrations of DOC. Forest floor depth and drainage area together explained much of the variation in ln Alm (R2 = 0.79; N = 45) and ln DOC (R2 = 0.87; N = 45). Linear regression models were moderately successful in predicting ln Alm and ln DOC in streams that were not included in model building. However, when back-transformed, predicted DOC concentrations were as much as 72% adrift from observed DOC concentrations and Alm concentrations were up to 51% off. This geographic approach to modelling Al and DOC is useful for general prediction, but for more detailed predictions, process-level biogeochemical models are required.

  9. Spatial pattern of heavy metals accumulation risk in urban soils of Beijing and its influencing factors.

    PubMed

    Liu, Rui; Wang, Meie; Chen, Weiping; Peng, Chi

    2016-03-01

    Accumulations of heavy metals in urban soils are highly spatial heterogeneity and affected by multiple factors including soil properties, land use and pattern, population and climatic conditions. We studied accumulation risks of Cd, Cu, Pb and Zn in unban soils of Beijing and their influencing based on the regression tree analysis and a GIS-based overlay model. Result shows that Zinc causes the most extensive soil pollution and Cu result in the most acute soil pollution. The soil's organic carbon content and CEC and population growth are the most significant factors affecting heavy metal accumulation. Other influence factors in land use pattern, urban landscape, and wind speed also contributed, but less pronounced. The soils in areas with higher degree of urbanization and surrounded by intense vehicular traffics have higher accumulation risk of Cd, Cu, Pb, and Zn. PMID:26716731

  10. Influencing Factors of Thermogenic Adipose Tissue Activity

    PubMed Central

    Zhang, Guoqing; Sun, Qinghua; Liu, Cuiqing

    2016-01-01

    Obesity is an escalating public health challenge and contributes tremendously to the disease burden globally. New therapeutic strategies are required to alleviate the health impact of obesity-related metabolic dysfunction. Brown adipose tissue (BAT) is specialized for dissipating chemical energy for thermogenesis as a defense against cold environment. Intriguingly, the brown-fat like adipocytes that dispersed throughout white adipose tissue (WAT) in rodents and humans, called “brite” or “beige” adipocytes, share similar thermogenic characteristics to brown adipocytes. Recently, researchers have focused on cognition of these thermogenic adipose tissues. Some factors have been identified to regulate the development and function of thermogenic adipose tissues. Cold exposure, pharmacological conditions, and lifestyle can enhance non-shivering thermogenesis and metabolism via some mechanisms. However, environmental pollutants, such as ambient fine particulates and ozone, may impair the function of these thermogenic adipose tissues and thereby induce metabolic dysfunction. In this review, the origin, function and influencing factors of thermogenic adipose tissues were summarized and it will provide insights into identifying new therapeutic strategies for the treatment of obesity and obesity-related diseases. PMID:26903879

  11. Influencing Factors of Thermogenic Adipose Tissue Activity.

    PubMed

    Zhang, Guoqing; Sun, Qinghua; Liu, Cuiqing

    2016-01-01

    Obesity is an escalating public health challenge and contributes tremendously to the disease burden globally. New therapeutic strategies are required to alleviate the health impact of obesity-related metabolic dysfunction. Brown adipose tissue (BAT) is specialized for dissipating chemical energy for thermogenesis as a defense against cold environment. Intriguingly, the brown-fat like adipocytes that dispersed throughout white adipose tissue (WAT) in rodents and humans, called "brite" or "beige" adipocytes, share similar thermogenic characteristics to brown adipocytes. Recently, researchers have focused on cognition of these thermogenic adipose tissues. Some factors have been identified to regulate the development and function of thermogenic adipose tissues. Cold exposure, pharmacological conditions, and lifestyle can enhance non-shivering thermogenesis and metabolism via some mechanisms. However, environmental pollutants, such as ambient fine particulates and ozone, may impair the function of these thermogenic adipose tissues and thereby induce metabolic dysfunction. In this review, the origin, function and influencing factors of thermogenic adipose tissues were summarized and it will provide insights into identifying new therapeutic strategies for the treatment of obesity and obesity-related diseases. PMID:26903879

  12. Factors influencing warfarin response in hospitalized patients

    PubMed Central

    Abdel-Aziz, Mahmoud I.; Ali, Mostafa A. Sayed; Hassan, Ayman K.M.; Elfaham, Tahani H.

    2015-01-01

    The objective of this study was to investigate the influence of simultaneous factors that potentially keep patients far from achieving target INR range at discharge in hospitalized patients. Prospective cross-sectional observational study conducted at the Cardiology Department and Intensive Care Unit (ICU) of the Assiut University Hospitals. One-hundred and twenty patients were enrolled in the study from July 2013 to January 2014. Outcome measures were discharge INRs, bleeding and thromboembolic episodes. Bivariate analysis and multinomial logistic regression were conducted to determine independent risk factors that can keep patients outside target INR range. Patients who were newly initiated warfarin on hospital admission were given low initiation dose (2.8 mg ± 0.9). They were more likely to have INR values below 1.5 during hospital stay, 13 (27.7%) patients compared with 9 (12.3%) previously treated patients, respectively (p = .034). We found that the best predictors of achieving below target INR range relative to within target INR range were; shorter hospital stay periods (OR, 0.82 for every day increase [95% CI, 0.72–0.94]), being a male patient (OR, 2.86 [95% CI, 1.05–7.69]), concurrent infection (OR, 0.21 [95% CI, 0.07–0.59]) and new initiation of warfarin therapy on hospital admission (OR, 3.73 [95% CI, 1.28–10.9]). Gender, new initiation of warfarin therapy on hospital admission, shorter hospital stay periods and concurrent infection can have a significant effect on discharge INRs. Initiation of warfarin without giving loading doses increases the risk of having INRs below 1.5 during hospital stay and increases the likelihood of a patient to be discharged with INR below target range. Following warfarin dosing nomograms and careful monitoring of the effect of various factors on warfarin response should be greatly considered. PMID:26702259

  13. Factors Influencing Efficacy of Bilayered Cell Therapy

    PubMed Central

    Allam, Reynald C.; Van Driessche, Freya; Zhu, Yiliang

    2014-01-01

    Objective: Diabetic foot ulcers (DFUs) that fail to heal with standard care should be treated with advanced wound care products. Efficacy of advanced therapies is dependent on many factors. A secondary analysis of pivotal trial data for a bilayered cellular construct used in the treatment of DFU was undertaken to determine if glycemic control and other factors had an effect on time to healing. Approach: We analyzed the effect of age, gender, diabetes type, insulin usage, body mass index, smoking, initial and ending glycohemoglobin (HgbA1c), Charcot deformity, and wound area, duration, and location on likelihood of healing for wounds treated with bilayered cellular construct (BLCC). Results: In those treated with BLCC, initial wound area (cm2), age, and history of Charcot deformity were found to significantly affect healing. Neither initial HgbA1c nor change in HgbA1c was associated with healing. The bilayered product was found to be equally effective regardless of initial or change in HgbA1c levels (p-values 0.94 and 0.44, respectively). In the control group, initial HgbA1c, insulin usage, female gender, and wound location at the toes significantly influenced healing. Innovation: BLCC subgroup analysis to elucidate selection criteria allowing for targeted use of advanced products on those more likely to respond as well as direct further research into prognostic indicators for BLCC-treated patients. Conclusion: The bilayered cellular construct product remains equally effective regardless of initial or change in HgbA1c levels. Further specific research into the effect of glucose control and other factors on the effectiveness of different advanced DFU treatment products is recommended. PMID:24940555

  14. "Push-Pull" Factors Influencing International Student Destination Choice.

    ERIC Educational Resources Information Center

    Mazzarol, Tim; Soutar, Geoffrey N.

    2002-01-01

    Examined factors motivating international student choice of host country. Found that economic and social factors within the home country serve to "push" students abroad, while a variety of "pull" factors influence selection of a host country. (EV)

  15. The Co-Influence of the Natural, Built, and Linguistic Landscape: Indexing Security

    ERIC Educational Resources Information Center

    Vickers, Caroline H.; Lindfelt, Christopher; Greer, Marsha

    2015-01-01

    This study examines physical aspects of place and how such visible aspects work to index a discourse of insecurity, including an insider-outsider binary, particularly through security signs in the linguistic landscape (LL). Our main focus is the relationship between policy and the uses of written language that appear in the LL in different census…

  16. Urban landscape features influencing rodent control and animal movement in two urban areas of California

    EPA Science Inventory

    “Pest” control of both native (e.g., gophers) and exotic (e.g., black rats, house mice) species may impact populations of non-target species inadvertently. We evaluated relationships among animal movement, rodent control, and landscape features in two urban locations in Californ...

  17. Landscape features influencing residential rodent control and animal movement in two urban areas of California

    EPA Science Inventory

    Residential “pest” control of both native (e.g., gophers, rabbits) and exotic (e.g., black and Norway rats, house mice) species may impact populations of non-target species inadvertently. We evaluated relationships among animal movement, rodent control, and landscape features in...

  18. Factors Driving Biofuel Crops' Influence on Climate

    NASA Astrophysics Data System (ADS)

    Jones, A.; Torn, M. S.; Riley, W. J.; Collins, W.

    2010-12-01

    grass parameters in CLM in order to identify a smaller set of parameters that exerts the most control on climatically relevant terms such as energy and carbon fluxes. By revealing those parameters that are most and least influential in terms of climate forcing, systematic sensitivity analysis helps to prioritize the search for observational data, constrains the process of tuning parameters to limited data, and leads the way to characterizing the uncertainty in biofuel crops’ influence on climate. Furthermore, due to similarities across managed ecosystems, these results offer general insight into those plant physiological properties and management factors that must be well-characterized in order to model changes in energy and carbon fluxes resulting from human land use.

  19. The influence of landscape matrix on isolated patch use by wide-ranging animals: conservation lessons for woodland caribou

    PubMed Central

    Lesmerises, Rémi; Ouellet, Jean-Pierre; Dussault, Claude; St-Laurent, Martin-Hugues

    2013-01-01

    For conservation purposes, it is important to design studies that explicitly quantify responses of focal species to different land management scenarios. Here, we propose an approach that combines the influence of landscape matrices with the intrinsic attributes of remaining habitat patches on the space use behavior of woodland caribou (Rangifer tarandus caribou), a threatened subspecies of Rangifer. We sought to link characteristics of forest remnants and their surrounding environment to caribou use (i.e., occurrence and intensity). We tracked 51 females using GPS telemetry north of the Saguenay River (Québec, Canada) between 2004 and 2010 and documented their use of mature forest remnants ranging between 30 and ∼170 000 ha in a highly managed landscape. Habitat proportion and anthropogenic feature density within incremental buffer zones (from 100 to 7500 m), together with intrinsic residual forest patch characteristics, were linked to caribou GPS location occurrence and density to establish the range of influence of the surrounding matrix. We found that patch size and composition influence caribou occurrence and intensity of use within a patch. Patch size had to reach approximately 270 km2 to attain 75% probability of use by caribou. We found that small patches (<100 km2) induced concentration of caribou activities that were shown to make them more vulnerable to predation and to act as ecological traps. Woodland caribou clearly need large residual forest patches, embedded in a relatively undisturbed matrix, to achieve low densities as an antipredator strategy. Our patch-based methodological approach, using GPS telemetry data, offers a new perspective of space use behavior of wide-ranging species inhabiting fragmented landscapes and allows us to highlight the impacts of large scale management. Furthermore, our study provides insights that might have important implications for effective caribou conservation and forest management. PMID:24101980

  20. The influence of landscape matrix on isolated patch use by wide-ranging animals: conservation lessons for woodland caribou.

    PubMed

    Lesmerises, Rémi; Ouellet, Jean-Pierre; Dussault, Claude; St-Laurent, Martin-Hugues

    2013-09-01

    For conservation purposes, it is important to design studies that explicitly quantify responses of focal species to different land management scenarios. Here, we propose an approach that combines the influence of landscape matrices with the intrinsic attributes of remaining habitat patches on the space use behavior of woodland caribou (Rangifer tarandus caribou), a threatened subspecies of Rangifer. We sought to link characteristics of forest remnants and their surrounding environment to caribou use (i.e., occurrence and intensity). We tracked 51 females using GPS telemetry north of the Saguenay River (Québec, Canada) between 2004 and 2010 and documented their use of mature forest remnants ranging between 30 and ∼170 000 ha in a highly managed landscape. Habitat proportion and anthropogenic feature density within incremental buffer zones (from 100 to 7500 m), together with intrinsic residual forest patch characteristics, were linked to caribou GPS location occurrence and density to establish the range of influence of the surrounding matrix. We found that patch size and composition influence caribou occurrence and intensity of use within a patch. Patch size had to reach approximately 270 km(2) to attain 75% probability of use by caribou. We found that small patches (<100 km(2)) induced concentration of caribou activities that were shown to make them more vulnerable to predation and to act as ecological traps. Woodland caribou clearly need large residual forest patches, embedded in a relatively undisturbed matrix, to achieve low densities as an antipredator strategy. Our patch-based methodological approach, using GPS telemetry data, offers a new perspective of space use behavior of wide-ranging species inhabiting fragmented landscapes and allows us to highlight the impacts of large scale management. Furthermore, our study provides insights that might have important implications for effective caribou conservation and forest management.

  1. Modeling Fluvial Incision and Transient Landscape Evolution: Influence of Dynamic Channel Adjustment

    NASA Astrophysics Data System (ADS)

    Attal, M.; Tucker, G. E.; Cowie, P. A.; Whittaker, A. C.; Roberts, G. P.

    2007-12-01

    Channel geometry exerts a fundamental control on fluvial processes. Recent work has shown that bedrock channel width (W) depends on a number of parameters, including channel slope, and is not only a function of drainage area (A) as is commonly assumed. The present work represents the first attempt to investigate the consequences, for landscape evolution, of using a static expression of channel width (W ~ A0.5) versus a relationship that allows channels to dynamically adjust to changes in slope. We consider different models for the evolution of the channel geometry, including constant width-to-depth ratio (after Finnegan et al., Geology, v. 33, no. 3, 2005), and width-to-depth ratio varying as a function of slope (after Whittaker et al., Geology, v. 35, no. 2, 2007). We use the Channel-Hillslope Integrated Landscape Development (CHILD) model to analyze the response of a catchment to a given tectonic disturbance. The topography of a catchment in the footwall of an active normal fault in the Apennines (Italy) is used as a template for the study. We show that, for this catchment, the transient response can be fairly well reproduced using a simple detachment-limited fluvial incision law. We also show that, depending on the relationship used to express channel width, initial steady-state topographies differ, as do transient channel width, slope, and the response time of the fluvial system. These differences lead to contrasting landscape morphologies when integrated at the scale of a whole catchment. Our results emphasize the importance of channel width in controlling fluvial processes and landscape evolution. They stress the need for using a dynamic hydraulic scaling law when modeling landscape evolution, particularly when the uplift field is non-uniform.

  2. Landscape-scale factors affecting feral horse habitat use during summer within the rocky mountain foothills.

    PubMed

    Girard, Tisa L; Bork, Edward W; Nielsen, Scott E; Neilsen, Scott E; Alexander, Mike J

    2013-02-01

    Public lands occupied by feral horses in North America are frequently managed for multiple uses with land use conflict occurring among feral horses, livestock, wildlife, and native grassland conservation. The factors affecting habitat use by horses is critical to understand where conflict may be greatest. We related horse presence and abundance to landscape attributes in a GIS to examine habitat preferences using 98 field plots sampled within a portion of the Rocky Mountain Forest Reserve of SW Alberta, Canada. Horse abundance was greatest in grassland and cut block habitats, and lowest in conifer and mixedwood forest. Resource selection probability functions and count models of faecal abundance indicated that horses preferred areas closer to water, with reduced topographic ruggedness, situated farther from forests, and located farther away from primary roads and trails frequented by recreationalists, but closer to small linear features (i.e. cut lines) that may be used as beneficial travel corridors. Horse presence and abundance were closely related to cattle presence during summer, suggesting that both herbivores utilise the same habitats. Estimates of forage biomass removal (44 %) by mid-July were near maximum acceptable levels. In contrast to horse-cattle associations, horses were negatively associated with wild ungulate abundance, although the mechanism behind this remains unclear and warrants further investigation. Our results indicate that feral horses in SW Alberta exhibit complex habitat selection patterns during spring and summer, including overlap in use with livestock. This finding highlights the need to assess and manage herbivore populations consistent with rangeland carrying capacity and the maintenance of range health.

  3. Landscape-Scale Factors Affecting Feral Horse Habitat Use During Summer Within The Rocky Mountain Foothills

    NASA Astrophysics Data System (ADS)

    Girard, Tisa L.; Bork, Edward W.; Neilsen, Scott E.; Alexander, Mike J.

    2013-02-01

    Public lands occupied by feral horses in North America are frequently managed for multiple uses with land use conflict occurring among feral horses, livestock, wildlife, and native grassland conservation. The factors affecting habitat use by horses is critical to understand where conflict may be greatest. We related horse presence and abundance to landscape attributes in a GIS to examine habitat preferences using 98 field plots sampled within a portion of the Rocky Mountain Forest Reserve of SW Alberta, Canada. Horse abundance was greatest in grassland and cut block habitats, and lowest in conifer and mixedwood forest. Resource selection probability functions and count models of faecal abundance indicated that horses preferred areas closer to water, with reduced topographic ruggedness, situated farther from forests, and located farther away from primary roads and trails frequented by recreationalists, but closer to small linear features (i.e. cut lines) that may be used as beneficial travel corridors. Horse presence and abundance were closely related to cattle presence during summer, suggesting that both herbivores utilise the same habitats. Estimates of forage biomass removal (44 %) by mid-July were near maximum acceptable levels. In contrast to horse-cattle associations, horses were negatively associated with wild ungulate abundance, although the mechanism behind this remains unclear and warrants further investigation. Our results indicate that feral horses in SW Alberta exhibit complex habitat selection patterns during spring and summer, including overlap in use with livestock. This finding highlights the need to assess and manage herbivore populations consistent with rangeland carrying capacity and the maintenance of range health.

  4. Influence of urban form on landscape pattern and connectivity in metropolitan regions: a comparative case study of Phoenix, AZ, USA, and Izmir, Turkey.

    PubMed

    Park, Sohyun; Hepcan, Çiğdem C; Hepcan, Şerif; Cook, Edward A

    2014-10-01

    Although ecological connectivity conservation in urban areas has recently been recognized as an important issue, less is known about its relationship to urban form and landscape pattern. This study investigates how urban morphology influences regional ecosystem pattern and landscape connectivity. Two metropolitan landscapes, Phoenix, AZ, USA, and Izmir, Turkey, were compared, both of which are fast-growing regions in their national context. A wide range of variables were considered for identifying natural and urban properties. The natural characteristics include typology of urban ecosystems, urban to natural cover ratio, dominant habitat type, urban biodiversity, landscape context, and connectivity conservation efforts. Urban parameters examine urban form, urban extent, urban cover proportion, growth rate, populations, urban gradient, major drivers of urbanization, urban density, and mode/approach of urban development. Twelve landscape metrics were measured and compared across the natural patches. Results show that there is little difference in landscape connectivity in the rural zones of Phoenix and Izmir, although Phoenix has slightly higher connectivity values. The connectivity variance in urbanized areas, however, is significantly dependent on the region. For example, Phoenix urban zones have substantially lower connectivity than either urban or suburban zones in Izmir. Findings demonstrate that small and compact urban settlements with more dense populations are more likely to conserve landscape connectivity compared to multiple-concentric but amalgamated urban form spreading all over the landscape (aka urban sprawl).

  5. Influence of urban form on landscape pattern and connectivity in metropolitan regions: a comparative case study of Phoenix, AZ, USA, and Izmir, Turkey.

    PubMed

    Park, Sohyun; Hepcan, Çiğdem C; Hepcan, Şerif; Cook, Edward A

    2014-10-01

    Although ecological connectivity conservation in urban areas has recently been recognized as an important issue, less is known about its relationship to urban form and landscape pattern. This study investigates how urban morphology influences regional ecosystem pattern and landscape connectivity. Two metropolitan landscapes, Phoenix, AZ, USA, and Izmir, Turkey, were compared, both of which are fast-growing regions in their national context. A wide range of variables were considered for identifying natural and urban properties. The natural characteristics include typology of urban ecosystems, urban to natural cover ratio, dominant habitat type, urban biodiversity, landscape context, and connectivity conservation efforts. Urban parameters examine urban form, urban extent, urban cover proportion, growth rate, populations, urban gradient, major drivers of urbanization, urban density, and mode/approach of urban development. Twelve landscape metrics were measured and compared across the natural patches. Results show that there is little difference in landscape connectivity in the rural zones of Phoenix and Izmir, although Phoenix has slightly higher connectivity values. The connectivity variance in urbanized areas, however, is significantly dependent on the region. For example, Phoenix urban zones have substantially lower connectivity than either urban or suburban zones in Izmir. Findings demonstrate that small and compact urban settlements with more dense populations are more likely to conserve landscape connectivity compared to multiple-concentric but amalgamated urban form spreading all over the landscape (aka urban sprawl). PMID:24934130

  6. The influence of natural factors on the concentrations of chemical elements in urban soils

    NASA Astrophysics Data System (ADS)

    Alekseenko, Alexey; Alekseenko, Vladimir

    2013-04-01

    The statistically treated results of more than 10 000 soil samples analyses for 25 elements were used during the work preparing. For estimating the total influence of natural factors on the global level we could consider the average concentrations in urban soils (the Clarke numbers of urban soils) with the average concentrations in the Earth crust and Earth soils. The analysis showed the heredity of general properties of elements concentrations from the Earth crust. However the higher concentrations of As, Cd, Cs, Mo, N, S, Ti and V in the soils of cities are explained by the combined effects of processes of soil formation and human impact, and Zn, Pb, Ba, Sr, Ca, Hg, B - by the prevailing human impact. On the regional level the natural factors influence was estimated by the comparing of soils of cities with the equal technogenic impact and number of population, but located in different geographical and climate zones. The common conformities with law were not found out, but the mentioned factors had an effect on the elements concentrations. The valuation of natural factors influence in the soils of one city was carried out by comparison the urban landscapes soils, which differ only in one characteristic. Geomorphologic peculiarities had the doubtless influence on the background concentrations of Pb, Sr, Ag, Zn, Yb, Co, Sn, Cr. etc., but in every case the connection of maximum and minimum background concentrations of the specific elements with the certain geomorphologic structures depended on number of building storeys, location of industrial zones, parks, etc. The certain associations of plants were also affected the background elements concentrations in soils of several cities. The increased concentrations of elements were more often detected - other things being equal - in the landscapes with mixed decorative fruit and berry plant association (?u, Pb, Co, Mn, Ti, Sr), less often - with agricultural fruit and berry plant association (Zn, Ag, Sn, Ba, Cr). In parks

  7. Landscape Changes Influence the Occurrence of the Melioidosis Bacterium Burkholderia pseudomallei in Soil in Northern Australia

    PubMed Central

    Kaestli, Mirjam; Mayo, Mark; Harrington, Glenda; Ward, Linda; Watt, Felicity; Hill, Jason V.; Cheng, Allen C.; Currie, Bart J.

    2009-01-01

    Background The soil-dwelling saprophyte bacterium Burkholderia pseudomallei is the cause of melioidosis, a severe disease of humans and animals in southeast Asia and northern Australia. Despite the detection of B. pseudomallei in various soil and water samples from endemic areas, the environmental habitat of B. pseudomallei remains unclear. Methodology/Principal Findings We performed a large survey in the Darwin area in tropical Australia and screened 809 soil samples for the presence of these bacteria. B. pseudomallei were detected by using a recently developed and validated protocol involving soil DNA extraction and real-time PCR targeting the B. pseudomallei–specific Type III Secretion System TTS1 gene cluster. Statistical analyses such as multivariable cluster logistic regression and principal component analysis were performed to assess the association of B. pseudomallei with environmental factors. The combination of factors describing the habitat of B. pseudomallei differed between undisturbed sites and environmentally manipulated areas. At undisturbed sites, the occurrence of B. pseudomallei was found to be significantly associated with areas rich in grasses, whereas at environmentally disturbed sites, B. pseudomallei was associated with the presence of livestock animals, lower soil pH and different combinations of soil texture and colour. Conclusions/Significance This study contributes to the elucidation of environmental factors influencing the occurrence of B. pseudomallei and raises concerns that B. pseudomallei may spread due to changes in land use. PMID:19156200

  8. Hydrothermal carbonization of biomass from landscape management - Influence of process parameters on soil properties of hydrochars.

    PubMed

    Röhrdanz, Michael; Rebling, Tammo; Ohlert, Jan; Jasper, Jan; Greve, Thomas; Buchwald, Rainer; von Frieling, Petra; Wark, Michael

    2016-05-15

    Besides pyrolysis the technology of hydrothermal carbonization (HTC) is tested to produce hydrochars for soil improvement. The chemical and physical properties of the hydrochars mainly depend on the feedstock and the process parameters reaction time and process temperature. Systematic investigations on the influences of these process parameters on soil properties of hydrochars like water holding capacity (WHC) and cation exchange capacity (CEC) are missing. In this study, a rush-rich biomass was carbonized within defined HTC process conditions under variation of reaction time and process temperature to produce hydrochars. Analysis of WHC, CEC, the elemental composition and Fourier-transform infrared spectroscopy (FT-IR) were performed to evaluate the influence of HTC process conditions on the pedological hydrochar properties. The results indicated that at increasing reaction severity (reaction time and process temperature) WHC and CEC decreased as well as the elemental O/C ratio. The decrease of WHC and CEC is based on the decrease of the hydrochar surface polarity. However, even the lowest WHC and CEC of investigated hydrochars still exceeded those of pure quartz sand by factors of 5-10. An application of hydrochars produced at severe HTC conditions could improve WHC and CEC of sandy soils. This has to be investigated in further studies. PMID:26974240

  9. Shallow groundwater dynamics across complex terrain: Influences of landscape position and climate

    NASA Astrophysics Data System (ADS)

    Jencso, K. G.; McGlynn, B. L.

    2014-12-01

    Prediction of hillslope and riparian water table dynamics across headwater catchments remains challenging. We suggest that this is partially due to the lack of spatially distributed, high frequency, long duration observations of shallow subsurface flows that connect hillsopes to riparian and stream landscape positions. Further, these observations are rarely considered in the context of both local and watershed scale structure and organization. Here, we provide a synthesis of shallow subsurface hydrologic connectivity duration and magnitude across 9 years of hourly stage recordings for 30 transects of shallow groundwater wells (hillslope size from 0.07 to 4.6 ha) in the Tenderfoot Creek Experimental Forest, MT. Key results include: 1) the annual average water table depth across all hillsope wells was exponentially related (r2 = 0.94) to upslope accumulated area (UAA). 2) K means analysis of the annual hilllsope water table stage duration curves indicated a transition across the continuum of wells from short duration hydrologic connectivity and low stage (UAA = 0.07 - 1ha, n= 90), sustained snowmelt hydrologic connectivity and moderate stage (UAA = 1.2 - 3ha, n = 20), and continuous hydrologic connectivity and highest stage (UAA = 3.1 - 4.6ha, n=11). 3) hillslopes with the largest UAA (n= 11; continuous connectivity and sustained groundwater stage) exhibited groundwater dynamics similar to those in riparian wells. The synthesis of the well water stage responses across space and time suggests strong emergent behavior according to landscape position and topography. These preliminary analyses provide insight into watershed behavior that is requisite for understanding where streamflow originates in the landscape, appropriate model structures for predicting streamflow, predicting landscape position sensitivity to climate variability, and informing land management decisions.

  10. Patch Size, Functional Isolation, Visibility and Matrix Permeability Influences Neotropical Primate Occurrence within Highly Fragmented Landscapes

    PubMed Central

    da Silva, Lucas Goulart; Ribeiro, Milton Cezar; Hasui, Érica; da Costa, Carla Aparecida; da Cunha, Rogério Grassetto Teixeira

    2015-01-01

    Forest fragmentation and habitat loss are among the major current extinction causes. Remaining fragments are mostly small, isolated and showing poor quality. Being primarily arboreal, Neotropical primates are generally sensitive to fragmentation effects. Furthermore, primates are involved in complex ecological process. Thus, landscape changes that negatively interfere with primate population dynamic affect the structure, composition, and ultimately the viability of the whole community. We evaluated if fragment size, isolation and visibility and matrix permeability are important for explaining the occurrence of three Neotropical primate species. Employing playback, we verified the presence of Callicebus nigrifrons, Callithrix aurita and Sapajus nigritus at 45 forest fragments around the municipality of Alfenas, Brazil. We classified the landscape and evaluated the metrics through predictive models of occurrence. We selected the best models through Akaike Selection Criterion. Aiming at validating our results, we applied the plausible models to another region (20 fragments at the neighboring municipality of Poço Fundo, Brazil). Twelve models were plausible, and three were validated, two for Sapajus nigritus (Area and Area+Visibility) and one for Callicebus nigrifrons (Area+Matrix). Our results reinforce the contribution of fragment size to maintain biodiversity within highly degraded habitats. At the same time, they stress the importance of including novel, biologically relevant metrics in landscape studies, such as visibility and matrix permeability, which can provide invaluable help for similar studies in the future and on conservation practices in the long run. PMID:25658108

  11. Temporal dynamics influenced by global change: bee community phenology in urban, agricultural, and natural landscapes.

    PubMed

    Leong, Misha; Ponisio, Lauren C; Kremen, Claire; Thorp, Robbin W; Roderick, George K

    2016-03-01

    Urbanization and agricultural intensification of landscapes are important drivers of global change, which in turn have direct impacts on local ecological communities leading to shifts in species distributions and interactions. Here, we illustrate how human-altered landscapes, with novel ornamental and crop plant communities, result not only in changes to local community diversity of floral-dependent species, but also in shifts in seasonal abundance of bee pollinators. Three years of data on the spatio-temporal distributions of 91 bee species show that seasonal patterns of abundance and species richness in human-altered landscapes varied significantly less compared to natural habitats in which floral resources are relatively scarce in the dry summer months. These findings demonstrate that anthropogenic environmental changes in urban and agricultural systems, here mediated through changes in plant resources and water inputs, can alter the temporal dynamics of pollinators that depend on them. Changes in phenology of interactions can be an important, though frequently overlooked, mechanism of global change.

  12. Influence of Landscape Diversity and Composition on the Parasitism of Cotton Bollworm Eggs in Maize

    PubMed Central

    Liu, Bing; Yang, Long; Yang, Yizhong; Lu, Yanhui

    2016-01-01

    We deployed >50,000 Helicoverpa armigera eggs in maize fields to assess the rate of parasitism by Trichogramma chilonis across 33 sites during a three-year span (2012–2014) in northern China. Subsequently, we used a partial least squares (PLS) regression approach to assess the relationship of landscape diversity with composition and parasitism potential. The parasitism rate of H. armigera eggs by T. chilonis ranged from 0–25.8%, with a mean value of 5.6%. Landscape diversity greatly enhanced parasitism at all four different spatial scales (0.5, 1.0, 1.5 and 2.0 km radius). Both the proportion of arable area and the total planting area of two major crops (cotton and maize) had a negative correlation to the parasitism rate at each scale, whereas parasitism was positively correlated to the proportion of host crops of H. armigera other than cotton and maize at the 0.5 to 2.0 km radius scales as well as to that of non-crop habitat at the 0.5 and 1.0 km radius scales. The study indicated that maintaining landscape diversity provided an important biocontrol service by limiting H. armigera through the egg parasitoid T. chilonis, whereas rapid agricultural intensification would greatly reduce the presence and parasitism of T. chilonis in China. PMID:26881784

  13. Influence of Landscape Diversity and Composition on the Parasitism of Cotton Bollworm Eggs in Maize.

    PubMed

    Liu, Bing; Yang, Long; Yang, Yizhong; Lu, Yanhui

    2016-01-01

    We deployed >50,000 Helicoverpa armigera eggs in maize fields to assess the rate of parasitism by Trichogramma chilonis across 33 sites during a three-year span (2012-2014) in northern China. Subsequently, we used a partial least squares (PLS) regression approach to assess the relationship of landscape diversity with composition and parasitism potential. The parasitism rate of H. armigera eggs by T. chilonis ranged from 0-25.8%, with a mean value of 5.6%. Landscape diversity greatly enhanced parasitism at all four different spatial scales (0.5, 1.0, 1.5 and 2.0 km radius). Both the proportion of arable area and the total planting area of two major crops (cotton and maize) had a negative correlation to the parasitism rate at each scale, whereas parasitism was positively correlated to the proportion of host crops of H. armigera other than cotton and maize at the 0.5 to 2.0 km radius scales as well as to that of non-crop habitat at the 0.5 and 1.0 km radius scales. The study indicated that maintaining landscape diversity provided an important biocontrol service by limiting H. armigera through the egg parasitoid T. chilonis, whereas rapid agricultural intensification would greatly reduce the presence and parasitism of T. chilonis in China. PMID:26881784

  14. Dendritic network models: Improving isoscapes and quantifying influence of landscape and in-stream processes on strontium isotopes in rivers

    NASA Astrophysics Data System (ADS)

    Brennan, Sean R.; Torgersen, Christian E.; Hollenbeck, Jeff P.; Fernandez, Diego P.; Jensen, Carrie K.; Schindler, Daniel E.

    2016-05-01

    A critical challenge for the Earth sciences is to trace the transport and flux of matter within and among aquatic, terrestrial, and atmospheric systems. Robust descriptions of isotopic patterns across space and time, called "isoscapes," form the basis of a rapidly growing and wide-ranging body of research aimed at quantifying connectivity within and among Earth's systems. However, isoscapes of rivers have been limited by conventional Euclidean approaches in geostatistics and the lack of a quantitative framework to apportion the influence of processes driven by landscape features versus in-stream phenomena. Here we demonstrate how dendritic network models substantially improve the accuracy of isoscapes of strontium isotopes and partition the influence of hydrologic transport versus local geologic features on strontium isotope ratios in a large Alaska river. This work illustrates the analytical power of dendritic network models for the field of isotope biogeochemistry, particularly for provenance studies of modern and ancient animals.

  15. Dendritic network models: Improving isoscapes and quantifying influence of landscape and in-stream processes on strontium isotopes in rivers

    USGS Publications Warehouse

    Brennan, Sean R.; Torgersen, Christian; Hollenbeck, Jeff P.; Fernandez, Diego P.; Jensen, Carrie K; Schindler, Daniel E.

    2016-01-01

    A critical challenge for the Earth sciences is to trace the transport and flux of matter within and among aquatic, terrestrial, and atmospheric systems. Robust descriptions of isotopic patterns across space and time, called “isoscapes,” form the basis of a rapidly growing and wide-ranging body of research aimed at quantifying connectivity within and among Earth's systems. However, isoscapes of rivers have been limited by conventional Euclidean approaches in geostatistics and the lack of a quantitative framework to apportion the influence of processes driven by landscape features versus in-stream phenomena. Here we demonstrate how dendritic network models substantially improve the accuracy of isoscapes of strontium isotopes and partition the influence of hydrologic transport versus local geologic features on strontium isotope ratios in a large Alaska river. This work illustrates the analytical power of dendritic network models for the field of isotope biogeochemistry, particularly for provenance studies of modern and ancient animals.

  16. Multi-scale factors influencing the characteristics of avian communities in urban parks across Beijing during the breeding season.

    PubMed

    Xie, Shilin; Lu, Fei; Cao, Lei; Zhou, Weiqi; Ouyang, Zhiyun

    2016-01-01

    Understanding the factors that influence the characteristics of avian communities using urban parks at both the patch and landscape level is important to focus management effort towards enhancing bird diversity. Here, we investigated this issue during the breeding season across urban parks in Beijing, China, using high-resolution satellite imagery. Fifty-two bird species were recorded across 29 parks. Analysis of residence type of birds showed that passengers were the most prevalent (37%), indicating that Beijing is a major node in the East Asian-Australasian Flyway. Park size was crucial for total species abundance, but foliage height diversity was the most important factor influencing avian species diversity. Thus, optimizing the configuration of vertical vegetation structure in certain park areas is critical for supporting avian communities in urban parks. Human visitation also showed negative impact on species diversity. At the landscape level, the percentage of artificial surface and largest patch index of woodland in the buffer region significantly affected total species richness, with insectivores and granivores being more sensitive to the landscape pattern of the buffer region. In conclusion, urban birds in Beijing are influenced by various multi-scale factors; however, these effects vary with different feeding types. PMID:27404279

  17. Multi-scale factors influencing the characteristics of avian communities in urban parks across Beijing during the breeding season

    PubMed Central

    Xie, Shilin; Lu, Fei; Cao, Lei; Zhou, Weiqi; Ouyang, Zhiyun

    2016-01-01

    Understanding the factors that influence the characteristics of avian communities using urban parks at both the patch and landscape level is important to focus management effort towards enhancing bird diversity. Here, we investigated this issue during the breeding season across urban parks in Beijing, China, using high-resolution satellite imagery. Fifty-two bird species were recorded across 29 parks. Analysis of residence type of birds showed that passengers were the most prevalent (37%), indicating that Beijing is a major node in the East Asian–Australasian Flyway. Park size was crucial for total species abundance, but foliage height diversity was the most important factor influencing avian species diversity. Thus, optimizing the configuration of vertical vegetation structure in certain park areas is critical for supporting avian communities in urban parks. Human visitation also showed negative impact on species diversity. At the landscape level, the percentage of artificial surface and largest patch index of woodland in the buffer region significantly affected total species richness, with insectivores and granivores being more sensitive to the landscape pattern of the buffer region. In conclusion, urban birds in Beijing are influenced by various multi-scale factors; however, these effects vary with different feeding types. PMID:27404279

  18. Multi-scale factors influencing the characteristics of avian communities in urban parks across Beijing during the breeding season.

    PubMed

    Xie, Shilin; Lu, Fei; Cao, Lei; Zhou, Weiqi; Ouyang, Zhiyun

    2016-01-01

    Understanding the factors that influence the characteristics of avian communities using urban parks at both the patch and landscape level is important to focus management effort towards enhancing bird diversity. Here, we investigated this issue during the breeding season across urban parks in Beijing, China, using high-resolution satellite imagery. Fifty-two bird species were recorded across 29 parks. Analysis of residence type of birds showed that passengers were the most prevalent (37%), indicating that Beijing is a major node in the East Asian-Australasian Flyway. Park size was crucial for total species abundance, but foliage height diversity was the most important factor influencing avian species diversity. Thus, optimizing the configuration of vertical vegetation structure in certain park areas is critical for supporting avian communities in urban parks. Human visitation also showed negative impact on species diversity. At the landscape level, the percentage of artificial surface and largest patch index of woodland in the buffer region significantly affected total species richness, with insectivores and granivores being more sensitive to the landscape pattern of the buffer region. In conclusion, urban birds in Beijing are influenced by various multi-scale factors; however, these effects vary with different feeding types.

  19. Multi-scale factors influencing the characteristics of avian communities in urban parks across Beijing during the breeding season

    NASA Astrophysics Data System (ADS)

    Xie, Shilin; Lu, Fei; Cao, Lei; Zhou, Weiqi; Ouyang, Zhiyun

    2016-07-01

    Understanding the factors that influence the characteristics of avian communities using urban parks at both the patch and landscape level is important to focus management effort towards enhancing bird diversity. Here, we investigated this issue during the breeding season across urban parks in Beijing, China, using high-resolution satellite imagery. Fifty-two bird species were recorded across 29 parks. Analysis of residence type of birds showed that passengers were the most prevalent (37%), indicating that Beijing is a major node in the East Asian–Australasian Flyway. Park size was crucial for total species abundance, but foliage height diversity was the most important factor influencing avian species diversity. Thus, optimizing the configuration of vertical vegetation structure in certain park areas is critical for supporting avian communities in urban parks. Human visitation also showed negative impact on species diversity. At the landscape level, the percentage of artificial surface and largest patch index of woodland in the buffer region significantly affected total species richness, with insectivores and granivores being more sensitive to the landscape pattern of the buffer region. In conclusion, urban birds in Beijing are influenced by various multi-scale factors; however, these effects vary with different feeding types.

  20. Groundwater influences on the distribution and abundance of riverine smallmouth bass, Micropterus dolomieu, in pasture landscapes of the midwestern USA

    USGS Publications Warehouse

    Brewer, Shannon K.

    2013-01-01

    This study examined how spring-flow (SF) contributions to streams related to the distribution and abundance of smallmouth bass Micropterus dolomieu in a predominately pasture landscape in Missouri, USA. Stream segments (N=13) with similar landscape characters were classified by SF volume into high SF (HSF) or low SF (LSF) groups. The densities of smallmouth bass, channel unit (CU) use and temperature-selection patterns were assessed for several life stages and frequency distributions for age 0 fish. More smallmouth bass were present in stream segments with HSF influence. Age 0 fish were twice as likely to be present in HSF stream segments. Older age classes were present in stream reaches independent of SF contribution. For all age classes, the use of particular CUs did not depend on SF influence. All age classes were more likely to be present in pools than other CUs. Microhabitat temperature selection differed among age classes. Age 0 fish selected warmer temperatures with a gradual shift towards cooler temperatures for older age classes. The length frequency of age 0 fish was skewed towards larger individuals in streams with limited SF influence, whereas the length frequency in HSF stream segments was skewed towards smaller individuals. The benefits of significant groundwater via SF influence seem to be related to increased hatch or survival of age 0 fish and the availability of optimal temperatures for adult smallmouth bass growth. Thermal refugia and stable flows provided by springs should be recognised for their biological potential to provide suitable habitat as climate change and other land-use alterations increase temperature regimes and alter flow patterns.

  1. Factors influencing triage decisions in mental health services.

    PubMed

    Grigg, Margaret; Herrman, Helen; Harvey, Carol; Endacott, Ruth

    2007-05-01

    The aim of the study was to identify the factors influencing the timing of an assessment after contact with a triage program in a community-based area mental health service in Australia. Triage decisions apparently were influenced by several groups of factors: patient characteristics; the source and mode of the contact with triage; and to a large extent by mental health service factors including the training, supervision and support of triage workers and the perceived availability of an assessment. While demand factors such as patient characteristics influenced the triage decision, supply factors also played an important role.

  2. Landscape characteristics and livestock presence influence common ravens: Relevance to greater sage-grouse conservation

    USGS Publications Warehouse

    Coates, Peter S.; Brussee, Brianne E.; Howe, Kristy; Gustafson, K. Ben; Casazza, Michael L.; Delehanty, David J.

    2016-01-01

    Common raven (Corvus corax; hereafter, raven) population abundance in the sagebrush steppe of the American West has increased threefold during the previous four decades, largely as a result of unintended resource subsidies from human land-use practices. This is concerning because ravens frequently depredate nests of species of conservation concern, such as greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse). Grazing by livestock in sagebrush ecosystems is common practice on most public lands, but associations between livestock and ravens are poorly understood. The primary objective of this study was to identify the effects of livestock on raven occurrence while accounting for landscape characteristics within human-altered sagebrush steppe habitat, particularly in areas occupied by breeding sage-grouse. Using data from southeastern Idaho collected during spring and summer across 3 yr, we modeled raven occurrence as a function of the presence of livestock while accounting for multiple landscape covariates, including land cover features, topographical features, and proximity to sage-grouse lek sites (breeding grounds), as well as site-level anthropogenic features. While accounting for landscape characteristics, we found that the odds of raven occurrence increased 45.8% in areas where livestock were present. In addition, ravens selected areas near sage-grouse leks, with the odds of occurrence decreasing 8.9% for every 1-km distance, increase away from the lek. We did not find an association between livestock use and distance to lek. We also found that ravens selected sites with relatively lower elevation containing increased amounts of cropland, wet meadow, and urbanization. Limiting raven access to key anthropogenic subsidies and spatially segregating livestock from sage-grouse breeding areas would likely reduce exposure of predatory ravens to sage-grouse nests and chicks.

  3. Influence of magnetic domain landscape on the flux dynamics in superconductor/ferromagnet bilayers

    NASA Astrophysics Data System (ADS)

    Adamus, Z.; Cieplak, Marta Z.; Kończykowski, M.; Zhu, L. Y.; Chien, C. L.

    2016-02-01

    We use a line of miniature Hall sensors to study the influence of the magnetic domain distribution on the flux dynamics in superconductor/ferromagnet bilayers. Two bilayers are built of a ferromagnetic Co/Pt multilayer with perpendicular magnetic anisotropy and a superconducting Nb layer, with the insulating layer in-between to avoid proximity effect. The magnetic domain patterns of various geometries are reversibly predefined in the Co/Pt multilayers using the appropriate magnetization procedure. The Pt thickness is different in the two bilayers, resulting in different width and length of the domains, which profoundly affects vortex dynamics. We show that narrow short domains lead to strong confinement of vortices at the sample edge, while narrow elongated domains of uniform width induce smaller confinement and easy vortex entry. Large enhancement of flux pinning and critical current density, by a factor of more than 7, is observed in the last case, while the former results in smaller enhancement. When domains are wide, the disorder in the domain widths becomes beneficial for larger enhancement of pinning, while more uniform distribution of domain widths results in a precipitous drop of the enhancement. The analysis of these results suggests that with increasing domain width, a transition occurs from vortex chains pinned by narrow domains to disordered triangular vortex lattice pinned by a maze of multiply interconnected magnetic domains.

  4. [Grain Size Distribution Characteristics of Suspended Particulate Matter as Influenced by the Apparent Pollution in the Eutrophic Urban Landscape Water Body].

    PubMed

    Gong, Dan-yan; Pan, Yang; Huang, Yong; Bao, Wei; Li, Qian-qian

    2016-03-15

    Grain size distribution characteristics of suspended particulate matter (SPM) reflects the apparent polluted condition of the urban landscape water. In order to explore the internal relationship between the eutrophication of urban landscape water's apparent pollution and grain size distribution of SPM, and its influencing factors, this paper selected five representative sampling sites in Feng Jin River which is a typical eutrophication river in Suzhou City, measured the grain size distribution of SPM, sensation pollution index (SPI) and water quality index, and analyzed their correlation. The results showed that: The rich nutrient water possessed a similar characteristics in grain size distribution. The grain size distribution of SPM in water was multimodal, and the the peak position was roughly the same; the grain size distribution of SPM was composed by multiple components. It could be roughly divided into six parts with the particle size range of every group being < 1.5 µm, 1.5-8 µm, 8-35 µm, 35-186 µm, 186-516 µm, > 516 µm. The component III was superior (with an average volume fraction of 38.3%-43.2%), and its volume fraction had a significant positive relation with the SPI value and the Chl-a content. The increase of component III volume fraction was the reflection of particle size's result of increasing SPI value. The increase of component III volume fraction was mainly derived from the increasing algal content. The volume fraction of group IV + group VI + group V was significantly higher under the condition of exogenous enter. When there was no exogenous component, the volume fraction of group IV + group VI + group V had a significant negative correlation with SPI value; when there were exogenous components, the volume fraction of group IV + group VI + group V had a weak positive correlation with SPI value, but the correlation did not reach a significant level. Environmental factors (Fv/Fm and DO) and exogenous factors had an influence by functioning

  5. [Grain Size Distribution Characteristics of Suspended Particulate Matter as Influenced by the Apparent Pollution in the Eutrophic Urban Landscape Water Body].

    PubMed

    Gong, Dan-yan; Pan, Yang; Huang, Yong; Bao, Wei; Li, Qian-qian

    2016-03-15

    Grain size distribution characteristics of suspended particulate matter (SPM) reflects the apparent polluted condition of the urban landscape water. In order to explore the internal relationship between the eutrophication of urban landscape water's apparent pollution and grain size distribution of SPM, and its influencing factors, this paper selected five representative sampling sites in Feng Jin River which is a typical eutrophication river in Suzhou City, measured the grain size distribution of SPM, sensation pollution index (SPI) and water quality index, and analyzed their correlation. The results showed that: The rich nutrient water possessed a similar characteristics in grain size distribution. The grain size distribution of SPM in water was multimodal, and the the peak position was roughly the same; the grain size distribution of SPM was composed by multiple components. It could be roughly divided into six parts with the particle size range of every group being < 1.5 µm, 1.5-8 µm, 8-35 µm, 35-186 µm, 186-516 µm, > 516 µm. The component III was superior (with an average volume fraction of 38.3%-43.2%), and its volume fraction had a significant positive relation with the SPI value and the Chl-a content. The increase of component III volume fraction was the reflection of particle size's result of increasing SPI value. The increase of component III volume fraction was mainly derived from the increasing algal content. The volume fraction of group IV + group VI + group V was significantly higher under the condition of exogenous enter. When there was no exogenous component, the volume fraction of group IV + group VI + group V had a significant negative correlation with SPI value; when there were exogenous components, the volume fraction of group IV + group VI + group V had a weak positive correlation with SPI value, but the correlation did not reach a significant level. Environmental factors (Fv/Fm and DO) and exogenous factors had an influence by functioning

  6. Influence of landscape structure and climate variability on a late holocene plant migration

    USGS Publications Warehouse

    Lyford, M.E.; Jackson, S.T.; Betancourt, J.L.; Gray, S.T.

    2003-01-01

    We analyzed and radiocarbon-dated 205 fossil woodrat middens from 14 sites in central and northern Wyoming and adjacent Utah and Montana to document spatiotemporal patterns of Holocene invasion by Utah juniper (Juniperus osteosperma). Holocene migration into central and northern Wyoming and southern Montana from the south proceeded by a series of long-distance dispersal events, which were paced by climate variability and structured by the geographic distribution and connectivity of suitable habitats on the landscape. The migration of Utah juniper into the region involved multiple long-distance dispersal events, ranging from 30 to 135 km. One of the earliest established populations, on East Pryor Mountain in south central Montana, is currently the northernmost population of the species. Establishment by long-distance dispersal of that population and another in the Bighorn Basin occurred during a period of relatively dry climate between 7500 and 5400 years ago. Further expansion of these initial colonizing populations and backfilling to occupy suitable sites to the south was delayed during a wet period from 5400 to 2800 years ago. Development of dry conditions 2800 years ago led to a rapid expansion in which Utah juniper colonized sites throughout its current range. Landscape structure and climate variability play important roles in governing the pattern and pace of natural invasions and deserve close attention in studying and modeling plant invasions, whether exotic or natural.

  7. Influence of landscape characteristics on migration strategies of white-tailed deer

    USGS Publications Warehouse

    Grovenburg, T.W.; Jacques, C.N.; Klaver, R.W.; Deperno, C.S.; Brinkman, T.J.; Swanson, C.C.; Jenks, J.A.

    2011-01-01

    A trade-off exists for migrating animals as to whether to migrate or remain residents. Few studies have documented relationships between landscape variables and deer migration strategies. From 2000 to 2007 we captured 267 adult female white-tailed deer (Odocoileus virginianus) at 7 study sites in Minnesota and South Dakota and monitored 149 individuals through ???3 seasonal migration periods (585 deer-migration seasons). All deer classified as obligate migrators with ???3 migrations (range 3-9 migration seasons) maintained their obligate status for the duration of the study. Multinomial logistic odds ratios from generalized estimating equations indicated that the odds of being a resident increased by 1.4 and 1.3 per 1-unit increase in forest patch density and mean area, respectively, compared to migrating deer. Odds of being an obligate migrator increased by 0.7 and 0.8 per 1-unit decrease in forest patch density and mean area, respectively, compared to resident or conditional migrating deer. Areas inhabited by resident deer were characterized by greater number of forest patches per 100 ha and larger mean forest patch area than conditional and obligate migrant areas. Odds of migrating increased by 1.1 per 1-unit increase in deer winter severity index. Migration behavior of white-tailed deer varied among regions, and land-cover and landscape characteristics provided predictive indicators of migration strategies for deer that could have important implications for conservation, metapopulation dynamics, and species management. ?? American 2011 Society of Mammalogists.

  8. The influence of mistletoes on birds in an agricultural landscape of central Mexico

    NASA Astrophysics Data System (ADS)

    Zuria, Iriana; Castellanos, Ignacio; Gates, J. Edward

    2014-11-01

    Mistletoes are hemiparasitic flowering plants that function as keystone resources in forests and woodlands of temperate regions, where a positive relationship between mistletoe density and avian species richness has been observed. Mistletoes have been less studied in tropical regions and the relationship between birds and mistletoes has seldom been explored in tropical agricultural systems. Therefore, we studied the presence of infected trees and infection prevalence (i.e., number of parasitized trees/total number of trees) by Psittacanthus (Loranthaceae) mistletoes in 23 hedgerows located in an agricultural landscape of central Mexico during the dry and rainy seasons, and investigated the relationship between bird species richness and abundance and the abundance of mistletoes. We found a mean of 74 mistletoe plants per 100-m transect of only one species, Psittacanthus calyculatus. Thirty-one percent of the trees surveyed were infected and tree species differed in infection prevalence, mesquite (Prosopis laevigata) being the most infected species with 86% of the surveyed trees infected. For both seasons, we found a positive and significant association between bird species richness and number of mistletoe plants. The same pattern was observed for total bird abundance. Many resident and Neotropical migratory birds were observed foraging on mistletoes. Our results show that mistletoes are important in promoting a higher bird species richness and abundance in tropical agricultural landscapes.

  9. Local habitat and landscape influence predation of bird nests on afforested Mediterranean cropland

    NASA Astrophysics Data System (ADS)

    Sánchez-Oliver, J. S.; Rey Benayas, J. M.; Carrascal, L. M.

    2014-07-01

    Afforestation programs such as the one promoted by the EU Common Agrarian Policy have contributed to spread tree plantations on former cropland. Nevertheless these afforestations may cause severe damage to open habitat species, especially birds of high conservation value. We investigated predation of artificial bird nests at young tree plantations and at the open farmland habitat adjacent to the tree plantations in central Spain. Predation rates were very high at both tree plantations (95.6%) and open farmland habitat (94.2%) after two and three week exposure. Plantation edge/area ratio and development of the tree canopy decreased predation rates and plantation area and magpie (Pica pica) abundance increased predation rates within tree plantations, which were also affected by land use types around plantations. The area of nearby tree plantations (positive effect), distance to the tree plantation edge (negative effect), and habitat type (mainly attributable to the location of nests in vineyards) explained predation rates at open farmland habitat. We conclude that predation rates on artificial nests were particularly high and rapid at or nearby large plantations, with high numbers of magpies and low tree development, and located in homogenous landscapes dominated by herbaceous crops and pastures with no remnants of semi-natural woody vegetation. Landscape planning should not favour tree plantations as the ones studied here in Mediterranean agricultural areas that are highly valuable for ground-nesting bird species.

  10. The influence of corridors on the movement behavior of individual Peromyscus polionotus in experimental landscapes.

    SciTech Connect

    Danielson, Brent J.; Hubbard, Michael W.

    1999-05-01

    To assess corridor effects on movement in Peromyscus polionotus (old-field mice), we used a set of three experimental landscapes that contained multiple patches (1.64 ha) of usable, open habitat embedded in a loblolly pine (Pinus taeda) forest matrix. Some patches were connected by corridors and others were isolated (unconnected). We introduced mice to nest boxes in experimental patches and followed them through the landscapes via trapping. We found weak evidence that the presence of corridors decreased the probability that P. polionotus (particularly females) would disperse or disappear from a patch. In the process of live trapping the patches, we also encountered ‘feral’ P. polionotus, Sigmodon hispidus (cotton rats), and Peromyscus gossypinus (cotton mice). The average number of feral animals did not differ between isolated and connected patches. This suggests that corridors do not act as drift fences that ‘sieve’ individuals out of the matrix and into the patches. However, more male than female P. polionotus and S. hispidus were trapped in isolated patches. This intersexual difference did not exist in connected patches.

  11. Landscape risk factors for attacks of vampire bats on cattle in Sao Paulo, Brazil.

    PubMed

    Gomes, Murilo Novaes; Monteiro, Antonio Miguel Vieira; Lewis, Nicola; Gonçalves, Celso Alberto; Filho, Vladimir de Souza Nogueira

    2010-02-01

    Vampire-bat (Desmodus rotundus) attacks on cattle are a major concern for cattle-raising area. Blood loss and paralytic rabies due to bat bites can impose severe losses on the livestock. We took four municipalities inside the Sao Joao da Boa Vista veterinary district (Sao Paulo, Brazil) as a study area and tested a set of landscape features for spatial correlation with distance to areas in which vampire-bat attacks on cattle were documented. Bat- and cattle-related data from the Sao Paulo State Rabies Control Program were used. Landscape data (first-order rivers and their tributaries, main roads, railways and urban areas) were obtained from official cartographic agencies; forest, sugarcane and pasture data were acquired from remote-sensing mappings. The study area was taken as a grid split into 178 cells. Each 4kmx4km cell was filled with bat, cattle and landscape data. Our analysis detected that grid cells that were closer to areas of bat attacks on cattle had higher cattle density and a greater percentage of the land committed to sugarcane cropping, and were close to forest fragments. These results shed light on the need for rethink the Rabies Control Program strategies for defining the surveillance of vampire-bat populations and rabies control in the state of Sao Paulo, Brazil.

  12. Landscape risk factors for attacks of vampire bats on cattle in Sao Paulo, Brazil.

    PubMed

    Gomes, Murilo Novaes; Monteiro, Antonio Miguel Vieira; Lewis, Nicola; Gonçalves, Celso Alberto; Filho, Vladimir de Souza Nogueira

    2010-02-01

    Vampire-bat (Desmodus rotundus) attacks on cattle are a major concern for cattle-raising area. Blood loss and paralytic rabies due to bat bites can impose severe losses on the livestock. We took four municipalities inside the Sao Joao da Boa Vista veterinary district (Sao Paulo, Brazil) as a study area and tested a set of landscape features for spatial correlation with distance to areas in which vampire-bat attacks on cattle were documented. Bat- and cattle-related data from the Sao Paulo State Rabies Control Program were used. Landscape data (first-order rivers and their tributaries, main roads, railways and urban areas) were obtained from official cartographic agencies; forest, sugarcane and pasture data were acquired from remote-sensing mappings. The study area was taken as a grid split into 178 cells. Each 4kmx4km cell was filled with bat, cattle and landscape data. Our analysis detected that grid cells that were closer to areas of bat attacks on cattle had higher cattle density and a greater percentage of the land committed to sugarcane cropping, and were close to forest fragments. These results shed light on the need for rethink the Rabies Control Program strategies for defining the surveillance of vampire-bat populations and rabies control in the state of Sao Paulo, Brazil. PMID:20004487

  13. Late Quaternary (Holocene) landscape evolution of a monsoon-influenced high Himalayan valley, Gori Ganga, Nanda Devi, NE Garhwal

    NASA Astrophysics Data System (ADS)

    Barnard, Patrick L.; Owen, Lewis A.; Sharma, Milap C.; Finkel, Robert C.

    2004-07-01

    The Garhwal Himalaya provides an excellent natural laboratory in which to examine landscape evolution in a monsoon-influenced high mountain environment. Geomorphic and sedimentological analysis and 10Be cosmogenic radionuclide (CRN) surface exposure dating of moraines, fans, and river and strath terraces in the Gori Ganga Valley of Nanda Devi, NE Garhwal, indicate that fans and river terraces developed rapidly by debris flow and flood processes during periods of deglaciation. These phases of high sediment transfer occurred at ˜1-2, ˜4-5, and ˜7-8 ka. Fan incision rates, subsequent to major times of resedimentation after each glacial advance, are between ˜19 and 57 mm/year. This contrasts with bedrock incision rates, based on mid-Holocene strath terraces, of ˜5 mm/year. These rates indicate that despite episodes of rapid denudation and resedimentation linked to glacial activity in this region, the background rates of denudation are similar to those for other regions of the Himalaya, averaging several millimeters per year. Furthermore, these data show the importance of climatic controls on landscape evolution and suggest a strong monsoonal control on the dynamics of earth surface processes in this region.

  14. Factors Influencing Career Choice among Police Recruits

    ERIC Educational Resources Information Center

    Cole, Bryan

    2012-01-01

    This quantitative, non-experimental study examined the career choice factors of 154 (n = 154) police recruits to determine a correlation of age group generation to the five career choice factors presented in the Sibson Reward of Work Model. Law enforcement agencies faced a shortage of viable candidates to fill vacant positions. While extensive…

  15. Is Subjective Status Influenced by Psychosocial Factors?

    ERIC Educational Resources Information Center

    Lundberg, Johanna; Kristenson, Margareta

    2008-01-01

    Objective: Associations between subjective status and health are still relatively unexplored. This study aimed at testing whether subjective status is uniquely confounded by psychosocial factors compared to objective status, and what factors that may predict subjective status. Design: A cross-sectional analysis of a population-based, random sample…

  16. Wetlands in changed landscapes: the influence of habitat transformation on the physico-chemistry of temporary depression wetlands.

    PubMed

    Bird, Matthew S; Day, Jenny A

    2014-01-01

    Temporary wetlands dominate the wet season landscape of temperate, semi-arid and arid regions, yet, other than their direct loss to development and agriculture, little information exists on how remaining wetlands have been altered by anthropogenic conversion of surrounding landscapes. This study investigates relationships between the extent and type of habitat transformation around temporary wetlands and their water column physico-chemical characteristics. A set of 90 isolated depression wetlands (seasonally inundated) occurring on coastal plains of the south-western Cape mediterranean-climate region of South Africa was sampled during the winter/spring wet season of 2007. Wetlands were sampled across habitat transformation gradients according to the areal cover of agriculture, urban development and alien invasive vegetation within 100 and 500 m radii of each wetland edge. We hypothesized that the principal drivers of physico-chemical conditions in these wetlands (e.g. soil properties, basin morphology) are altered by habitat transformation. Multivariate multiple regression analyses (distance-based Redundancy Analysis) indicated significant associations between wetland physico-chemistry and habitat transformation (overall transformation within 100 and 500 m, alien vegetation cover within 100 and 500 m, urban cover within 100 m); although for significant regressions the amount of variation explained was very low (range: ∼2 to ∼5.5%), relative to that explained by purely spatio-temporal factors (range: ∼35.5 to ∼43%). The nature of the relationships between each type of transformation in the landscape and individual physico-chemical variables in wetlands were further explored with univariate multiple regressions. Results suggest that conservation of relatively narrow (∼100 m) buffer strips around temporary wetlands is likely to be effective in the maintenance of natural conditions in terms of physico-chemical water quality.

  17. Wetlands in Changed Landscapes: The Influence of Habitat Transformation on the Physico-Chemistry of Temporary Depression Wetlands

    PubMed Central

    Bird, Matthew S.; Day, Jenny A.

    2014-01-01

    Temporary wetlands dominate the wet season landscape of temperate, semi-arid and arid regions, yet, other than their direct loss to development and agriculture, little information exists on how remaining wetlands have been altered by anthropogenic conversion of surrounding landscapes. This study investigates relationships between the extent and type of habitat transformation around temporary wetlands and their water column physico-chemical characteristics. A set of 90 isolated depression wetlands (seasonally inundated) occurring on coastal plains of the south-western Cape mediterranean-climate region of South Africa was sampled during the winter/spring wet season of 2007. Wetlands were sampled across habitat transformation gradients according to the areal cover of agriculture, urban development and alien invasive vegetation within 100 and 500 m radii of each wetland edge. We hypothesized that the principal drivers of physico-chemical conditions in these wetlands (e.g. soil properties, basin morphology) are altered by habitat transformation. Multivariate multiple regression analyses (distance-based Redundancy Analysis) indicated significant associations between wetland physico-chemistry and habitat transformation (overall transformation within 100 and 500 m, alien vegetation cover within 100 and 500 m, urban cover within 100 m); although for significant regressions the amount of variation explained was very low (range: ∼2 to ∼5.5%), relative to that explained by purely spatio-temporal factors (range: ∼35.5 to ∼43%). The nature of the relationships between each type of transformation in the landscape and individual physico-chemical variables in wetlands were further explored with univariate multiple regressions. Results suggest that conservation of relatively narrow (∼100 m) buffer strips around temporary wetlands is likely to be effective in the maintenance of natural conditions in terms of physico-chemical water quality. PMID:24533161

  18. Landscape characteristics influencing the genetic structure of greater sage-grouse within the stronghold of their range: a holistic modeling approach.

    PubMed

    Row, Jeffrey R; Oyler-McCance, Sara J; Fike, Jennifer A; O'Donnell, Michael S; Doherty, Kevin E; Aldridge, Cameron L; Bowen, Zachary H; Fedy, Bradley C

    2015-05-01

    Given the significance of animal dispersal to population dynamics and geographic variability, understanding how dispersal is impacted by landscape patterns has major ecological and conservation importance. Speaking to the importance of dispersal, the use of linear mixed models to compare genetic differentiation with pairwise resistance derived from landscape resistance surfaces has presented new opportunities to disentangle the menagerie of factors behind effective dispersal across a given landscape. Here, we combine these approaches with novel resistance surface parameterization to determine how the distribution of high- and low-quality seasonal habitat and individual landscape components shape patterns of gene flow for the greater sage-grouse (Centrocercus urophasianus) across Wyoming. We found that pairwise resistance derived from the distribution of low-quality nesting and winter, but not summer, seasonal habitat had the strongest correlation with genetic differentiation. Although the patterns were not as strong as with habitat distribution, multivariate models with sagebrush cover and landscape ruggedness or forest cover and ruggedness similarly had a much stronger fit with genetic differentiation than an undifferentiated landscape. In most cases, landscape resistance surfaces transformed with 17.33-km-diameter moving windows were preferred, suggesting small-scale differences in habitat were unimportant at this large spatial extent. Despite the emergence of these overall patterns, there were differences in the selection of top models depending on the model selection criteria, suggesting research into the most appropriate criteria for landscape genetics is required. Overall, our results highlight the importance of differences in seasonal habitat preferences to patterns of gene flow and suggest the combination of habitat suitability modeling and linear mixed models with our resistance parameterization is a powerful approach to discerning the effects of landscape

  19. Landscape characteristics influencing the genetic structure of greater sage-grouse within the stronghold of their range: a holistic modeling approach

    USGS Publications Warehouse

    Row, Jeff R; Oyler-McCance, Sara J.; Fike, Jennifer; O'Donnell, Michael; Doherty, Kevin E.; Aldridge, Cameron L.; Bowen, Zachary H.; Fedy, Brad C

    2015-01-01

    Given the significance of animal dispersal to population dynamics and geographic variability, understanding how dispersal is impacted by landscape patterns has major ecological and conservation importance. Speaking to the importance of dispersal, the use of linear mixed models to compare genetic differentiation with pairwise resistance derived from landscape resistance surfaces has presented new opportunities to disentangle the menagerie of factors behind effective dispersal across a given landscape. Here, we combine these approaches with novel resistance surface parameterization to determine how the distribution of high- and low-quality seasonal habitat and individual landscape components shape patterns of gene flow for the greater sage-grouse (Centrocercus urophasianus) across Wyoming. We found that pairwise resistance derived from the distribution of low-quality nesting and winter, but not summer, seasonal habitat had the strongest correlation with genetic differentiation. Although the patterns were not as strong as with habitat distribution, multivariate models with sagebrush cover and landscape ruggedness or forest cover and ruggedness similarly had a much stronger fit with genetic differentiation than an undifferentiated landscape. In most cases, landscape resistance surfaces transformed with 17.33-km-diameter moving windows were preferred, suggesting small-scale differences in habitat were unimportant at this large spatial extent. Despite the emergence of these overall patterns, there were differences in the selection of top models depending on the model selection criteria, suggesting research into the most appropriate criteria for landscape genetics is required. Overall, our results highlight the importance of differences in seasonal habitat preferences to patterns of gene flow and suggest the combination of habitat suitability modeling and linear mixed models with our resistance parameterization is a powerful approach to discerning the effects of landscape

  20. Landscape characteristics influencing the genetic structure of greater sage-grouse within the stronghold of their range: a holistic modeling approach.

    PubMed

    Row, Jeffrey R; Oyler-McCance, Sara J; Fike, Jennifer A; O'Donnell, Michael S; Doherty, Kevin E; Aldridge, Cameron L; Bowen, Zachary H; Fedy, Bradley C

    2015-05-01

    Given the significance of animal dispersal to population dynamics and geographic variability, understanding how dispersal is impacted by landscape patterns has major ecological and conservation importance. Speaking to the importance of dispersal, the use of linear mixed models to compare genetic differentiation with pairwise resistance derived from landscape resistance surfaces has presented new opportunities to disentangle the menagerie of factors behind effective dispersal across a given landscape. Here, we combine these approaches with novel resistance surface parameterization to determine how the distribution of high- and low-quality seasonal habitat and individual landscape components shape patterns of gene flow for the greater sage-grouse (Centrocercus urophasianus) across Wyoming. We found that pairwise resistance derived from the distribution of low-quality nesting and winter, but not summer, seasonal habitat had the strongest correlation with genetic differentiation. Although the patterns were not as strong as with habitat distribution, multivariate models with sagebrush cover and landscape ruggedness or forest cover and ruggedness similarly had a much stronger fit with genetic differentiation than an undifferentiated landscape. In most cases, landscape resistance surfaces transformed with 17.33-km-diameter moving windows were preferred, suggesting small-scale differences in habitat were unimportant at this large spatial extent. Despite the emergence of these overall patterns, there were differences in the selection of top models depending on the model selection criteria, suggesting research into the most appropriate criteria for landscape genetics is required. Overall, our results highlight the importance of differences in seasonal habitat preferences to patterns of gene flow and suggest the combination of habitat suitability modeling and linear mixed models with our resistance parameterization is a powerful approach to discerning the effects of landscape

  1. Landscape characteristics influencing the genetic structure of greater sage-grouse within the stronghold of their range: a holistic modeling approach

    PubMed Central

    Row, Jeffrey R; Oyler-McCance, Sara J; Fike, Jennifer A; O'Donnell, Michael S; Doherty, Kevin E; Aldridge, Cameron L; Bowen, Zachary H; Fedy, Bradley C

    2015-01-01

    Given the significance of animal dispersal to population dynamics and geographic variability, understanding how dispersal is impacted by landscape patterns has major ecological and conservation importance. Speaking to the importance of dispersal, the use of linear mixed models to compare genetic differentiation with pairwise resistance derived from landscape resistance surfaces has presented new opportunities to disentangle the menagerie of factors behind effective dispersal across a given landscape. Here, we combine these approaches with novel resistance surface parameterization to determine how the distribution of high- and low-quality seasonal habitat and individual landscape components shape patterns of gene flow for the greater sage-grouse (Centrocercus urophasianus) across Wyoming. We found that pairwise resistance derived from the distribution of low-quality nesting and winter, but not summer, seasonal habitat had the strongest correlation with genetic differentiation. Although the patterns were not as strong as with habitat distribution, multivariate models with sagebrush cover and landscape ruggedness or forest cover and ruggedness similarly had a much stronger fit with genetic differentiation than an undifferentiated landscape. In most cases, landscape resistance surfaces transformed with 17.33-km-diameter moving windows were preferred, suggesting small-scale differences in habitat were unimportant at this large spatial extent. Despite the emergence of these overall patterns, there were differences in the selection of top models depending on the model selection criteria, suggesting research into the most appropriate criteria for landscape genetics is required. Overall, our results highlight the importance of differences in seasonal habitat preferences to patterns of gene flow and suggest the combination of habitat suitability modeling and linear mixed models with our resistance parameterization is a powerful approach to discerning the effects of landscape

  2. Influences of roads and development on bird communities in protected Chihuahuan Desert landscapes

    USGS Publications Warehouse

    Gutzwiller, K.J.; Barrow, W.C.

    2003-01-01

    Our objective was to improve knowledge about effects of broad-scale road and development variables on bird communities in protected desert landscapes. Bird species richness and the relative abundance or probability of occurrence of many species were significantly associated with total length of roads within each of two spatial extents (1- and 2-km radii), distance to the nearest road, distance to the nearest development, or the two-way interactions of these variables. Regression models reflected non-linear relations, interaction effects, spatial-extent effects, and interannual variation. Road and development effects warrant special attention in protected areas because such places may be important sources of indigenous bird communities in a region.

  3. Influences of the Landscape on Life Cycle Carbon Intensity of Biofuels

    NASA Astrophysics Data System (ADS)

    Adler, P. R.; Del Grosso, S.; Parton, W. J.; Spatari, S.

    2011-12-01

    Biofuels derived from first (sugar and starch based) and second (lignocellulosic) generation agricultural feedstocks will continue to expand into the market between now and 2022 as incentivized through the federal Energy Independence and Security Act (EISA). Nitrogen use is one of the key environmental concerns within the life cycle since it is both the dominant source of life cycle greenhouse gas (GHG) emissions (energy from N fertilizer production and N2O emissions) and poses risks of reactive N movement throughout agricultural landscapes and watersheds. The other dominant components of the feedstock production on life cycle GHG emissions are tillage and land use change impacts on soil organic carbon (SOC). Opportunities to reduce reactive N through winter double crops may satisfy the dual goal of mitigating N2O emissions and reducing NO3 loses while meeting the objectives of EISA. However, changes in N2O, NO3, and SOC are variable within the agricultural landscape due to soil texture, climate, and crop rotation history thereby increasing the complexity of developing mitigation recommendations. Moreover, the inherent variability in N2O emissions makes it difficult to develop single life cycle carbon intensity profiles for specific fuel pathways that apply across the US, since those pathways will have geographic dependencies. Estimating the expected changes in N2O and SOC is an integral part of quantifying the life cycle GHG profile of biofuels derived from winter double crop feedstocks, while NO3 losses affect both indirect N2O emissions and water quality. The biogeochemical model DayCent was used to simulate the impact of growing winter barley as a double crop following corn before soybean establishment during the winter fallow period for six states in the Mid Atlantic region of the Eastern US on SOC and direct and indirect N2O. EPA is currently reviewing the addition of an advanced fuel pathway for winter barley in the Mid Atlantic region as part of the RFS2

  4. Soil influence on the performance of 26 native herbaceous plants suitable for sustainable Mediterranean landscaping

    NASA Astrophysics Data System (ADS)

    Bretzel, Francesca; Pezzarossa, Beatrice; Benvenuti, Stefano; Bravi, Alessio; Malorgio, Fernando

    2009-09-01

    Native herbaceous plants have the potential for renaturalizing and recovering derelict soils, such as urban or anthropized soils. Ecological restoration following the establishment of a native wildflower meadow should lead to a reduction in management costs and to the preservation of native plant populations. This study was aimed at determining the ecological characteristics and the cultivation needs of 26 herbaceous species native to Italy and southern Europe in order to identify their landscape potential in low-maintenance conditions. The species were selected on the basis of their adaptation to unproductive soils in semi-natural and rural areas, and on their ornamental value, including their ability to attract insects. Mono-specific plots were set up in three different soils. Seed germination, seedling emergence, flowering dynamics, and plant growth were determined. Dormancy-breaking treatments were effective in improving the germination of most species. The percentage of field establishment and biomass appeared to be affected by the physical and chemical characteristics of the soil. Soil texture slightly affected seedling emergence, whereas soil texture and the C and N levels affected plant growth, the number of flowers and the duration of flowering. Dianthus carthusianorum, Verbascum blattaria, Matricaria chamomilla and Hypochoeris radicata developed a higher biomass per plant in the soils with a low nutrient content, indicating their adaptability to infertile soils. Daucus carota, Papaver rhoeas, Verbascum sinuatum, Coleostephus myconis produced a higher biomass per plant in the most fertile soil, where they appeared to show a higher potential when competing with other species. The ecological characteristics shown by the native plants are extremely important in terms of combining seeds of different species to create and to maintain semi-natural herbaceous communities in low-maintenance landscapes.

  5. Landscape influences on climate-related lake shrinkage at high latitudes

    USGS Publications Warehouse

    Roach, Jennifer K.; Griffith, Brad; Verbyla, David

    2013-01-01

    Climate-related declines in lake area have been identified across circumpolar regions and have been characterized by substantial spatial heterogeneity. An improved understanding of the mechanisms underlying lake area trends is necessary to predict where change is most likely to occur and to identify implications for high latitude reservoirs of carbon. Here, using a population of ca. 2300 lakes with statistically significant increasing and decreasing lake area trends spanning longitudinal and latitudinal gradients of ca. 1000 km in Alaska, we present evidence for a mechanism of lake area decline that involves the loss of surface water to groundwater systems. We show that lakes with significant declines in lake area were more likely to be located: (1) in burned areas; (2) on coarser, well-drained soils; and (3) farther from rivers compared to lakes that were increasing. These results indicate that postfire processes such as permafrost degradation, which also results from a warming climate, may promote lake drainage, particularly in coarse-textured soils and farther from rivers where overland flooding is less likely and downslope flow paths and negative hydraulic gradients between surface water and groundwater systems are more common. Movement of surface water to groundwater systems may lead to a deepening of subsurface flow paths and longer hydraulic residence time which has been linked to increased soil respiration and CO2 release to the atmosphere. By quantifying relationships between statewide coarse resolution maps of landscape characteristics and spatially heterogeneous responses of lakes to environmental change, we provide a means to identify at-risk lakes and landscapes and plan for a changing climate.

  6. Degree of Landscape Fragmentation Influences Genetic Isolation among Populations of a Gliding Mammal

    PubMed Central

    Taylor, Andrea C.; Walker, Faith M.; Goldingay, Ross L.; Ball, Tina; van der Ree, Rodney

    2011-01-01

    Forests and woodlands are under continuing pressure from urban and agricultural development. Tree-dependent mammals that rarely venture to the ground are likely to be highly sensitive to forest fragmentation. The Australian squirrel glider (Petaurus norfolcensis) provides an excellent case study to examine genetic (functional) connectivity among populations. It has an extensive range that occurs in a wide band along the east coast. However, its forest and woodland habitat has become greatly reduced in area and is severely fragmented within the southern inland part of the species' range, where it is recognised as threatened. Within central and northern coastal regions, habitat is much more intact and we thus hypothesise that genetic connectivity will be greater in this region than in the south. To test this we employed microsatellite analysis in a molecular population biology approach. Most sampling locations in the highly modified south showed signatures of genetic isolation. In contrast, a high level of genetic connectivity was inferred among most sampled populations in the more intact habitat of the coastal region, with samples collected 1400 km apart having similar genetic cluster membership. Nonetheless, some coastal populations associated with urbanisation and agriculture are genetically isolated, suggesting the historic pattern observed in the south is emerging on the coast. Our study demonstrates that massive landscape changes following European settlement have had substantial impacts on levels of connectivity among squirrel glider populations, as predicted on the basis of the species' ecology. This suggests that landscape planning and management in the south should be focused on restoring habitat connectivity where feasible, while along the coast, existing habitat connectivity must be maintained and recent losses restored. Molecular population biology approaches provide a ready means for identifying fragmentation effects on a species at multiple scales

  7. Does Habitat Heterogeneity in a Multi-Use Landscape Influence Survival Rates and Density of a Native Mesocarnivore?

    PubMed Central

    Gese, Eric M.; Thompson, Craig M.

    2014-01-01

    The relationships between predators, prey, and habitat have long been of interest to applied and basic ecologists. As a native Great Plains mesocarnivore of North America, swift foxes (Vulpes velox) depended on the historic disturbance regime to maintain open grassland habitat. With a decline in native grasslands and subsequent impacts to prairie specialists, notably the swift fox, understanding the influence of habitat on native predators is paramount to future management efforts. From 2001 to 2004, we investigated the influence of vegetation structure on swift fox population ecology (survival and density) on and around the Piñon Canyon Maneuver Site, southeastern Colorado, USA. We monitored 109 foxes on 6 study sites exposed to 3 different disturbance regimes (military training, grazing, unused). On each site we evaluated vegetation structure based on shrub density, basal coverage, vegetation height, and litter. Across all sites, annual fox survival rates ranged from 0.50 to 0.92 for adults and 0.27 to 0.78 for juveniles. Among sites, population estimates ranged from 1 to 7 foxes per 10 km transect. Fox density or survival was not related to the relative abundance of prey. A robust model estimating fox population size and incorporating both shrub density and percent basal cover as explanatory variables far outperformed all other models. Our results supported the idea that, in our region, swift foxes were shortgrass prairie specialists and also indicated a relationship between habitat quality and landscape heterogeneity. We suggest the regulation of swift fox populations may be based on habitat quality through landscape-mediated survival, and managers may effectively use disturbance regimes to create or maintain habitat for this native mesocarnivore. PMID:24963713

  8. Tectonic versus climate influence on landscape evolution: A case study from the upper Spiti valley, NW Himalaya

    NASA Astrophysics Data System (ADS)

    Anoop, A.; Prasad, S.; Basavaiah, N.; Brauer, A.; Shahzad, F.; Deenadayalan, K.

    2012-04-01

    We have undertaken structural, geomorphological, and morphometric analyses to investigate the role of tectonism and climate in the landscape evolution in the upper Spiti valley, NW Himalayas. Geomorphometric analyses coupled with field investigations reveal active tectonic deformation in the Spiti region. The calculated geomorphic indices (steepness, concavity and Hack) demonstrate uplift/subsidence along the Kaurik-Chango fault, whereas transverse topographic index (T-index) reveals basin tilting associated with active faulting near Hansa and Lingti valley. Investigation of well-dated Mane palaeolake sediments also provides evidence of regional tectonic instability. Four episodes (ca. 7.8, 7.4, 6.5 and 6.1 cal ka) of neotectonic activity have been identified during the period of the lake's existence. We have also compiled data on the regional climate variability and compared it with the age of the Mane palaeo-landslide. Our results indicate that the landslide occurred towards the end of the early Holocene intensified monsoon phase and is located near an active fault. Our data on regional tectonic instability and the coincidences of modern and palaeo-landslides with zones of active deformation suggest that tectonism is an important factor governing landscape stability in the Spiti region.

  9. Environmental factors that influence the location of crop agriculture in the conterminous United States

    USGS Publications Warehouse

    Baker, Nancy T.; Capel, Paul D.

    2011-01-01

    Most crops are grown on land with shallow slope where the temperature, precipitation, and soils are favorable. In areas that are too steep, wet, or dry, landscapes have been modified to allow cultivation. Some of the limitations of the environmental factors that determine the location of agriculture can be overcome through modifications, but others cannot. On a larger-than-field scale, agricultural modifications commonly influence water availability through irrigation and (or) drainage and soil fertility and (or) organic-matter content through amendments such as manure, commercial fertilizer and lime. In general, it is not feasible to modify the other environmental factors, soil texture, soil depth, soil mineralogy, temperature, and terrain at large scales.

  10. Factors influencing host susceptibility to meningococcal disease.

    PubMed

    Winstanley, F P; Blackwell, C C; Weir, D M

    1985-01-01

    Host-parasite interactions influencing the development of the protective humoral immune response to Neisseria meningitidis are briefly reviewed. Possible consequences of the observed decreased titres of bactericidal activity specific for meningococcal serogroups A, B and C among patients with gonorrhoea are discussed with reference to: the epidemiology of the two diseases, the protective role of "natural" antibodies to the Neisseria species and the carriage rate of serogroupable strains of N. meningitidis among patients with gonorrhoea and a control population.

  11. Quantifying landscape resilience using vegetation indices

    NASA Astrophysics Data System (ADS)

    Eddy, I. M. S.; Gergel, S. E.

    2014-12-01

    Landscape resilience refers to the ability of systems to adapt to and recover from disturbance. In pastoral landscapes, degradation can be measured in terms of increased desertification and/or shrub encroachment. In many countries across Central Asia, the use and resilience of pastoral systems has changed markedly over the past 25 years, influenced by centralized Soviet governance, private property rights and recently, communal resource governance. In Kyrgyzstan, recent governance reforms were in response to the increasing degradation of pastures attributed to livestock overgrazing. Our goal is to examine and map the landscape-level factors that influence overgrazing throughout successive governance periods. Here, we map and examine some of the spatial factors influencing landscape resilience in agro-pastoral systems in the Kyrgyzstan Republic where pastures occupy >50% of the country's area. We ask three questions: 1) which mechanisms of pasture degradation (desertification vs. shrub encroachment), are detectable using remote sensing vegetation indices?; 2) Are these degraded pastures associated with landscape features that influence herder mobility and accessibility (e.g., terrain, distance to other pastures)?; and 3) Have these patterns changed through successive governance periods? Using a chronosequence of Landsat imagery (1999-2014), NDVI and other VIs were used to identify trends in pasture condition during the growing season. Least-cost path distances as well as graph theoretic indices were derived from topographic factors to assess landscape connectivity (from villages to pastures and among pastures). Fieldwork was used to assess the feasibility and accuracy of this approach using the most recent imagery. Previous research concluded that low herder mobility hindered pasture use, thus we expect the distance from pasture to village to be an important predictor of pasture condition. This research will quantify the magnitude of pastoral degradation and test

  12. Environmental factors influencing growth and pubertal development.

    PubMed Central

    Delemarre-van de Waal, H A

    1993-01-01

    Postnatal growth is based on hereditary signals and environmental factors in a complex regulatory network. Each factor must be in an optimal state for normal growth of the child. Fetal conditions may also have consequences on postnatal height. Intrauterine growth retardation can be recovered postnatally, although postnatal growth remains depressed in about one-third of cases. After birth, the environment may exert either a positive or negative effect on growth. In underdeveloped countries, malnutrition plays a major role in inhibiting the growth process. Children from families of higher socioeconomic classes are taller than their coevals in the lower socioeconomic groups. Urbanization also has a positive effect on growth. Better child care is supported by sufficient food supply, appropriate health and sanitation services, and a higher level of education. Over the last century, these factors have induced a taller stature and a more rapid maturity in Europe, North America, and Australia; a phenomenon which has been referred to as "the secular trend" in growth. Recently, a secular trend has also been reported in some developing countries. Although urbanization in general appears to be associated with better conditions of living, this is not the case in the slums of South America or in Africa where rural children are better off than children living in the poor cities. This paper describes in more detail the different hereditary and environmental factors that act during the fetal period and postnatally, and which play a role in human growth and pubertal development. PMID:8243404

  13. Factors Influencing uUniversity Research Performance

    ERIC Educational Resources Information Center

    Edgar, Fiona; Geare, Alan

    2013-01-01

    This research extends our understanding of research productivity by examining features of managerial practice and culture within university departments. Adopting a robust comparative research design, capturing both interview and survey data sourced from multiple stakeholders from New Zealand universities, we seek to identify factors associated…

  14. The Influence of Noneconomic Factors on Negotiators

    ERIC Educational Resources Information Center

    Tracy, Lane

    1974-01-01

    Certain noneconomic factors in collective bargaining are directly related to the negotiator's personal inclination to settle for the new contract. In this study, the pattern of relationships between the parties, the nature of the work itself, favorable recognition, team policy, and interpersonal relationships proved to be significantly related to…

  15. Factors Influencing Recruitment in Educational Psychology

    ERIC Educational Resources Information Center

    Frederickson, Norah

    2003-01-01

    This paper reports an investigation of the factors that educational psychologists in training (EPiTs) look for when applying for jobs in educational psychology services. Relevant literature on "job attraction" is reviewed and a three-stage research process employed. This involved a focus group approach to questionnaire generation followed by…

  16. Mycobacterium paratuberculosis. Factors that influence mycobactin dependence.

    PubMed

    Lambrecht, R S; Collins, M T

    1992-01-01

    Mycobacterium paratuberculosis does not produce any detectable mycobactin, an iron-binding compound that is synthesized by most Mycobacterium spp. and necessary for the growth of all mycobacteria. This study examined the influence of various culture conditions on mycobactin dependence in M. paratuberculosis. Using a radiometric growth assay, we found the minimal concentration of mycobactin J necessary for growth of M. paratuberculosis to be 0.006 microM, whereas 1.2 microM (1 microgram/ml) was required for optimal growth. In media without mycobactin at iron concentrations less than or equal to 100 microM, growth of M. paratuberculosis occurred at pH 5.0, but not pH 6.8. Iron concentrations greater than 100 microM did not significantly increase growth at pH 5.0, but at pH 6.8 the growth rate increased with increasing amounts of iron reaching a rate equal to control cultures containing mycobactin. Mycobacterium paratuberculosis appeared to lose mycobactin dependence when subcultured; however, this was subsequently shown to be a result of mycobactin carried over from primary medium. Removal of this contaminating cell-wall-associated mycobactin reestablished mycobactin dependence. We conclude that mycobactin dependence must be carefully determined because it is a key test used in identification of M. paratuberculosis and may be easily influenced by media pH, iron concentration, and mycobactin carryover from primary media. PMID:1582168

  17. Influence of hereditary factors in psychogenic disorders.

    PubMed

    Muhs, A; Schepank, H

    1995-01-01

    As part of a research project, a sample of 50 pairs of twins (21 pairs of identical twins, 16 pairs of nonidentical twins of the same sex, and 13 pairs of male-female twins, n = 100 test persons) was examined between 1963 and 1969 and recently, 20 years later, followed up. The index twins were drawn from among the patients making use of the services of an outpatient clinic; they had been diagnosed as having psychoneurotic, character-neurotic of psychosomatic disorders. The question again looked into was that of nature versus nurture: identical twins displayed significantly higher similarity with regard to both severity of their neuroses and manifestation of neurotic symptoms than did nonidentical twins. The hereditary factor proved to be of greater import for the continuing childhood neuroses than for the subsiding childhood neuroses. Yet a certain hereditary factor effect was observed for the neuroses which first manifest themselves in adulthood. Our findings indicate that the hereditary factor is not more pronounced in childhood than in adulthood; it is equally effective in adults. PMID:7480573

  18. Landscape of fear influences the relative importance of consumptive and nonconsumptive predator effects.

    PubMed

    Matassa, Catherine M; Trussell, Geoffrey C

    2011-12-01

    Predators can initiate trophic cascades by consuming and/or scaring their prey. Although both forms of predator effect can increase the overall abundance of prey's resources, nonconsumptive effects may be more important to the spatial and temporal distribution of resources because predation risk often determines where and when prey choose to forage. Our experiment characterized temporal and spatial variation in the strength of consumptive and nonconsumptive predator effects in a rocky intertidal food chain consisting of the predatory green crab (Carcinus maenas), an intermediate consumer (the dogwhelk, Nucella lapillus), and barnacles (Semibalanus balanoides) as a resource. We tracked the survival of individual barnacles through time to map the strength of predator effects in experimental communities. These maps revealed striking spatiotemporal patterns in Nucella foraging behavior in response to each predator effect. However, only the nonconsumptive effect of green crabs produced strong spatial patterns in barnacle survivorship. Predation risk may play a pivotal role in determining the small-scale distribution patterns of this important rocky intertidal foundation species. We suggest that the effects of predation risk on individual foraging behavior may scale up to shape community structure and dynamics at a landscape level. PMID:22352165

  19. Landscape of fear influences the relative importance of consumptive and nonconsumptive predator effects.

    PubMed

    Matassa, Catherine M; Trussell, Geoffrey C

    2011-12-01

    Predators can initiate trophic cascades by consuming and/or scaring their prey. Although both forms of predator effect can increase the overall abundance of prey's resources, nonconsumptive effects may be more important to the spatial and temporal distribution of resources because predation risk often determines where and when prey choose to forage. Our experiment characterized temporal and spatial variation in the strength of consumptive and nonconsumptive predator effects in a rocky intertidal food chain consisting of the predatory green crab (Carcinus maenas), an intermediate consumer (the dogwhelk, Nucella lapillus), and barnacles (Semibalanus balanoides) as a resource. We tracked the survival of individual barnacles through time to map the strength of predator effects in experimental communities. These maps revealed striking spatiotemporal patterns in Nucella foraging behavior in response to each predator effect. However, only the nonconsumptive effect of green crabs produced strong spatial patterns in barnacle survivorship. Predation risk may play a pivotal role in determining the small-scale distribution patterns of this important rocky intertidal foundation species. We suggest that the effects of predation risk on individual foraging behavior may scale up to shape community structure and dynamics at a landscape level.

  20. Surface factors influencing burnout on flat heaters

    SciTech Connect

    Ramilison, J.M.; Sadasivan, P.; Lienhard, J.H. )

    1992-02-01

    Ever since Kutateladze (1951) and Zuber (1958) proposed hydrodynamic descriptions of the burnout heat flux, q{sub max}, confusion has marked the scope of their agreed-upon equation. The problem stems from Kutateladze's original correlation. The mischief in all of this is that Zuber's sketches and other aspects of his derivation suggested that he was deriving an expression applicable to a flat heater. In fact, Zuber operated under the premise - later disproved by many investigators - that the geometry did not affect burnout. His comparison of his prediction with Kutateladze's correlation did not reflect a lack of care. It reflected the conviction that geometry did not matter. As one looks more closely, surface conditions become more important than once thought. The objective of this paper is to take into account the influence of the condition of the heater surface in recreating a correlation of q{sub max} for horizontal heaters.

  1. Factors influencing the algebra ``reversal error''

    NASA Astrophysics Data System (ADS)

    Cohen, Elaine; Kanim, Stephen E.

    2005-11-01

    Given a written problem statement about a proportional relationship between two quantities, many students will place the constant of proportionality on the wrong side of the equals sign. Introductory physics is one of the first courses in which students encounter multiple-step problems that require algebraic (rather than numeric) solutions, and this "reversal error" is relatively common in student solutions to these types of problems. We describe an investigation into three possible influences on students who make this reversal error: variable symbol choice, sentence structure, and context familiarity. Our results, from a calculus-based physics course and an intermediate algebra course, show that sentence structure is the most significant of these three possibilities. However, sentence structure alone does not provide a complete explanation for the reversal error.

  2. Mapping the Cultural Learnability Landscape of Danger

    ERIC Educational Resources Information Center

    Barrett, H. Clark; Peterson, Christopher D.; Frankenhuis, Willem E.

    2016-01-01

    Cultural transmission is often viewed as a domain-general process. However, a growing literature suggests that learnability is influenced by content and context. The idea of a learnability landscape is introduced as a way of representing the effects of interacting factors on how easily information is acquired. Extending prior work (Barrett &…

  3. Treatment Factors That Influence Mortality in Acromegaly.

    PubMed

    McCabe, John; Ayuk, John; Sherlock, Mark

    2016-01-01

    Acromegaly is a rare condition characterized by excessive secretion of growth hormone (GH), which is almost always due to a pituitary adenoma. Acromegaly is associated with significant morbidity such as hypertension, type 2 diabetes, cardiomyopathy, obstructive sleep apnoea, malignancy and musculoskeletal abnormalities. Acromegaly has also been associated with increased mortality in several retrospective studies. This review will focus on the epidemiological data relating to mortality rates in acromegaly, the relationship between acromegaly and malignancy, the role of GH and insulin-like growth factor-I in assessing the risk of future mortality, and the impact of radiotherapy and hypopituitarism on mortality.

  4. Factors influencing job satisfaction of oncology nurses over time.

    PubMed

    Cummings, Greta; Olson, Karin; Raymond-Seniuk, Christy; Lo, Eliza; Masaoud, Elmabrok; Bakker, Debra; Fitch, Margaret; Green, Esther; Butler, Lorna; Conlon, Michael

    2013-01-01

    In this study, we tested a structural equation model to examine work environment factors related to changes in job satisfaction of oncology nurses between 2004 and 2006. Relational leadership and good physician/nurse relationships consistently influenced perceptions of enough RNs to provide quality care, and freedom to make patient care decisions, which, in turn, directly influenced nurses' job satisfaction over time. Supervisor support in resolving conflict and the ability to influence patient care outcomes were significant influences on job satisfaction in 2004, whereas, in 2006, a clear philosophy of nursing had a greater significant influence. Several factors that influence job satisfaction of oncology nurses in Canada have changed over time, which may reflect changes in work environments and work life. These findings suggest opportunities to modify work conditions that could improve nurses' job satisfaction and work life.

  5. Factors influencing the spinal motoneurons in development

    PubMed Central

    Wiese, Stefan

    2015-01-01

    The development of the spinal cord needs a concerted interaction of transcription factors activating diverse genes and signals from outside acting on the specification of the different cells. Signals have to act on the segments of the embryo as well as on the cranial-caudal axis and the dorso-ventral axis. Additionally the axons of the motoneurons have to cross the central nervous system barrier to connect to the periphery. Intensive anatomical studies have been followed by molecular characterization of the different subsets of transcription factors that are expressed by cells of the developing spinal cord. Here, intensive studies for the most important appearing cells, the motoneurons, have resulted in a good knowledge on the expression patterns of these proteins. Nonetheless motoneurons are by far not the only important cells and the concert activity of all cells besides them is necessary for the correct function and integrity of motoneurons within the spinal cord. This article will briefly summarize the different aspects on spinal cord development and focuses on the differentiation as well as the functionalization of motoneurons. PMID:26807112

  6. Luminous Landscapes.

    ERIC Educational Resources Information Center

    Okrent, Inez

    2000-01-01

    Describes an activity for third-grade students in which they learn about early American landscape painters, specifically Frederick Church, Thomas Moran, and Albert Bierstadt. Students create natural landscapes, using the basic elements of landscape compositions. Discusses the process. (CMK)

  7. Factors influencing the intention to watch online video advertising.

    PubMed

    Lee, Joonghwa; Lee, Mira

    2011-10-01

    This study examines the factors influencing consumer intention to watch online video ads, by applying the theory of reasoned action. The attitude toward watching online video ads, the subjective norm, and prior frequency of watching online video ads positively influence the intention to watch online video ads. Further, beliefs held about entertainment and information outcomes from watching online video ads and subjective norm influence attitude toward watching these ads.

  8. Factors influencing the intention to watch online video advertising.

    PubMed

    Lee, Joonghwa; Lee, Mira

    2011-10-01

    This study examines the factors influencing consumer intention to watch online video ads, by applying the theory of reasoned action. The attitude toward watching online video ads, the subjective norm, and prior frequency of watching online video ads positively influence the intention to watch online video ads. Further, beliefs held about entertainment and information outcomes from watching online video ads and subjective norm influence attitude toward watching these ads. PMID:21476837

  9. The Influence of Societal Factors on Female Body Image.

    ERIC Educational Resources Information Center

    Monteath, Sheryl A.; McCabe, Marita P.

    1997-01-01

    Investigates the influence of societal factors on Western women's perceptions of their bodies. Finds that women typically underestimate their body size and want smaller bodies; two-fifths of women expressed negative feelings about their bodies; and that body satisfaction is best explained by societal influences, self-esteem and body mass index.…

  10. Factors Influencing the Disabled's Employment in the Competitive Labour Market.

    ERIC Educational Resources Information Center

    Mannila, Simo

    1995-01-01

    Factors influencing the job search outcomes of 1,353 Finnish individuals with disabilities were studied, focusing on age, gender, domicile, basic education, vocational training, and type of disability. Results showed that age, education, and domicile influenced outcomes, and labor market status was to some extent gender specific. (JDD)

  11. Phytotoxic concentrations of subsoil aluminum as influenced by soils and landscape position

    SciTech Connect

    Beyrouty, C.A.; Keino, J.K.; Gbur, E.E.; Hanson, M.G.

    2000-02-01

    Subsoil Al can restrict deep root growth which, under dryland conditions, can cause lower yields during periods of water deficit. Soils that have high levels of subsoil Al must be identified so that appropriate management strategies, such as selection of deep rooting, Al tolerant cultivars or chemical amelioration of the subsoil, can be implemented. Thirteen soils representing three landscape positions from the Southern Mississippi Valley were sampled to 75 cm at 15-cm depth increments. Short-term bioassays were conducted with wheat (Triticum aestivum L.), cotton (Gossypium hirsutum L.), and soybean (Glycine max (L.) Merr.) at each depth increment to identify soils with potentially phytotoxic concentrations of Al. Subsoil pH values generally decreased with depth to a low of 4.1 at the 45- to 60-cm depth increment. Values of 1N KCl-extractable Al were as high as 1,010 mg kg{sup {minus}1} in the 60- to 75-cm depth increment, whereas exchangeable Ca concentrations dropped as low as 207 mg kg{sup {minus}1}. Concentrations of 1N KCl-extractable Al in soils of the Loessial Plains were nearly twice those measured in soils from the Loessial Hills and more than three times greater than soils from the Bottomlands and Terraces. aluminum (KCl-extractable) concentrations that resulted in a 30% reduction in root length varied among crop species and ranged from 2 mg kg{sup {minus}1} to more than 667 mg kg{sup {minus}1}. Subsoil Al is a problem for a significant percentage of hectarage in the Southern Mississippi Valley and should be taken into consideration, especially under dryland farming.

  12. Factors influencing whether children walk to school.

    PubMed

    Su, Jason G; Jerrett, Michael; McConnell, Rob; Berhane, Kiros; Dunton, Genevieve; Shankardass, Ketan; Reynolds, Kim; Chang, Roger; Wolch, Jennifer

    2013-07-01

    Few studies have simultaneously evaluated multiple levels of influence on whether children walk to school. A large cohort of 4338 subjects from 10 communities was used to identify the determinants of walking through (1) a one-level logistic regression model for individual-level variables and (2) a two-level mixed regression model for individual and school-level variables. Walking rates were positively associated with home-to-school proximity, greater age, and living in neighborhoods characterized by lower traffic density. Greater land use mix around the home was, however, associated with lower rates of walking. Rates of walking to school were also higher amongst recipients of the Free and Reduced Price Meals Program and attendees of schools with higher percentage of English language learners. Designing schools in the same neighborhood as residential districts should be an essential urban planning strategy to reduce walking distance to school. Policy interventions are needed to encourage children from higher socioeconomic status families to participate in active travel to school and to develop walking infrastructures and other measures that protect disadvantaged children. PMID:23707968

  13. Factors Influencing Whether Children Walk to School

    PubMed Central

    Su, Jason G.; Jerrett, Michael; Mcconnell, Rob; Berhane, Kiros; Dunton, Genevieve; Shankardass, Ketan; Reynolds, Kim; Chang, Roger; Wolch, Jennifer

    2015-01-01

    Few studies have evaluated multiple levels of influence simultaneously on whether children walk to school. A large cohort of 4,338 subjects from ten communities was used to identify the determinants of walking through (1) a one-level logistic regression model for individual-level variables and (2) a two-level mixed regression model for individual and school-level variables. Walking rates were positively associated with home-to-school proximity, greater age, and living in neighborhoods characterized by lower traffic density. Greater land use mix around the home was, however, associated with lower rates of walking. Rates of walking to school were also higher amongst recipients of the Free and Reduced Price Meals Program and attendees of schools with higher percentage of English language learners. Designing schools in the same neighborhood as residential districts should be an essential urban planning strategy to reduce walking distance to school. Policy interventions are needed to encourage children from higher socioeconomic status families to participate in active travel to school and to develop walking infrastructures and other measures that protect disadvantaged children. PMID:23707968

  14. Physical factors influence for biologic systems

    NASA Astrophysics Data System (ADS)

    Piruzyan, L. A.

    2005-08-01

    Physical methods are widely spread in diagnostics and therapy of different pathologies, especially in oncology. The application of lasers occurred to be the perspective approach for combined methods application in medicine. Our work is devoted to investigation of thermal effect of focused laser beam in the model of Garding-Passi melanoma and also to the study of free radicals activity after the radiation with non-focused laser beam. The histologic alterations correlated with theoretical calculations of temperature distribution in irradiated tissue for energies 30-60 J attracted our interest. The values of maximal temperatures in depths of tissue for energies 30-60 J were carried out. In the model of permanent magnetic field (PMF) effect for mice ascites sarcoma 37 we have showed the linear dependence of tumor growth inhibition from the period of PMF treatment. Simultaneously we investigated PMF influence for free radical"s (FR) concentrations in mice organs and tissues and potentially appearing questions of PMF effect for biopotential in connection with FR formation. We have also studied the alterations of K, Na and Ca ions concentrations in ascetic fluids after animal"s PMF treatment. We revealed some reasons of biopotential generation and concluded that biopotential is not the result of specific ions gradient only but its generation can be followed by free radicals states appearance and occurrence of semi-conductivity in biostructures.

  15. Factors influencing bacterial adhesion to contact lenses

    PubMed Central

    Dutta, Debarun; Willcox, Mark

    2012-01-01

    The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The adhesion of this strain reaches maximum numbers within 1h in most in vitro studies and a biofilm has generally formed within 24 h of cells adhering to the lens surface. Physical and chemical properties of contact lens material affect bacterial adhesion. The water content of hydroxyethylmethacrylate (HEMA)-based lenses and their iconicity affect the ability of bacteria to adhere. The higher hydrophobicity of silicone hydrogel lenses compared to HEMA-based lenses has been implicated in the higher numbers of bacteria that can adhere to their surfaces. Lens wear has different effects on bacterial adhesion, partly due to differences between wearers, responses of bacterial strains and the ability of certain tear film proteins when bound to a lens surface to kill certain types of bacteria. PMID:22259220

  16. Factors influencing riverine fish assemblages in Massachusetts

    USGS Publications Warehouse

    Armstrong, David S.; Richards, Todd A.; Levin, Sara B.

    2011-01-01

    The U.S. Geological Survey, in cooperation with the Massachusetts Department of Conservation and Recreation, Massachusetts Department of Environmental Protection, and the Massachusetts Department of Fish and Game, conducted an investigation of fish assemblages in small- to medium-sized Massachusetts streams. The objective of this study was to determine relations between fish-assemblage characteristics and anthropogenic factors, including impervious cover and estimated flow alteration, relative to the effects of environmental factors, including physical-basin characteristics and land use. The results of this investigation supersede those of a preliminary analysis published in 2010. Fish data were obtained for 669 fish-sampling sites from the Massachusetts Division of Fisheries and Wildlife fish-community database. A review of the literature was used to select fish metrics - species richness, abundance of individual species, and abundances of species grouped on life history traits - responsive to flow alteration. The contributing areas to the fish-sampling sites were delineated and used with a geographic information system to determine a set of environmental and anthropogenic factors that were tested for use as explanatory variables in regression models. Reported and estimated withdrawals and return flows were used together with simulated unaltered streamflows to estimate altered streamflows and indicators of flow alteration for each fish-sampling site. Altered streamflows and indicators of flow alteration were calculated on the basis of methods developed in a previous U.S. Geological Survey study in which unaltered daily streamflows were simulated for a 44-year period (water years 1961-2004), and streamflow alterations were estimated by use of water-withdrawal and wastewater-return data previously reported to the State for the 2000-04 period and estimated domestic-well withdrawals and septic-system discharges. A variable selection process, conducted using principal

  17. Factors influencing phototaxis in nocturnal migrating birds.

    PubMed

    Zhao, Xuebing; Chen, Mingyan; Wu, Zhaolu; Wang, Zijiang

    2014-12-01

    Many migratory bird species fly during the night (nocturnal migrants) and have been shown to display some phototaxis to artificial light. During 2006 to 2009, we investigated phototaxis in nocturnal migrants at Jinshan Yakou in Xinping County (N23°56', E101°30'; 2400 m above sea-level), and at the Niaowang Mountain in Funing County (N23°30', E105°35'; 1400 m above sea-level), both in the Yunnan Province of Southwest China. A total of 5069 birds, representing 129 species, were captured by mist-netting and artificial light. The extent of phototaxis effect on bird migration was examined during all four seasons, three phases of the moon, and under two weather conditions (mist and wind). Data were statistically analyzed to determine the extent to which these factors may impact phototaxis of nocturnal migrants. The results point to phototaxis in birds migrating in the spring and autumn, especially in the autumn. Furthermore, migrating birds were more readily attracted to artificial lights during nights with little moonlight, mist, and a headwind. Regardless of the initial orientation in which birds flew, either following the wind or against the wind, birds would always fly against the wind when flying towards the light. This study broadens our understanding of the nocturnal bird migration, potentially resulting in improved bird ringing practices, increased awareness, and better policies regarding bird protection.

  18. Factors influencing visits to school nurses by pregnant adolescents.

    PubMed

    Chen, S P; Telleen, S; Mitchell, D R; Chen, E H

    1992-01-01

    The influence of five factors on the first visit to school nurses by pregnant adolescents and adequacy of prenatal care was analyzed. Only one factor, age of baby's father, was found to be associated with adequacy of prenatal care. PMID:1518672

  19. Factors Influencing Psychological Help Seeking in Adults: A Qualitative Study

    ERIC Educational Resources Information Center

    Topkaya, Nursel

    2015-01-01

    The aim of the current research is to identify which factors, and in what direction these factors influence adults' decisions to seek psychological help for their personal problems. The research was designed as a phenomenology model; the data was gathered through the semi-structured interview technique, which is mostly used in qualitative research…

  20. Factors Influencing Technology Planning in Developing Countries: A Literature Review

    ERIC Educational Resources Information Center

    Keengwe, Jared; Malapile, Sandy

    2014-01-01

    This article is a literature review concerning the factors that play an important role in the development of educational technology plans in the educational system of developing countries (DCs). Largely, the technology plans are influenced by factors that emanates from within the country (internal) and those outside of their borders (external).…

  1. Factors Influencing Pursuit of Higher Education: Validating a Questionnaire.

    ERIC Educational Resources Information Center

    Harris, Sandra M.

    This paper explains the process used to validate the construct validity of the Factors Influencing Pursuit of Higher Education Questionnaire. This questionnaire is a literature-based, researcher-developed instrument which gathers information on the factors thought to affect a person's decision to pursue higher education. The questionnaire includes…

  2. Psychosocial Factors Influencing Competency of Children's Statements on Sexual Trauma

    ERIC Educational Resources Information Center

    Kim, Tae Kyung; Choi, Soul; Shin, Yee Jin

    2011-01-01

    Objectives: The objectives of this study are to assess children's competence to state their traumatic experience and to determine psychosocial factors influencing the competency of children's statements, such as emotional factors of children and parents and trauma-related variables, in Korean child sex abuse victims. Methods: We enrolled 214…

  3. A Survey of Factors Influencing High School Start Times

    ERIC Educational Resources Information Center

    Wolfson, Amy R.; Carskadon, Mary A.

    2005-01-01

    The present study surveyed high school personnel regarding high school start times, factors influencing school start times, and decision making around school schedules. Surveys were analyzed from 345 secondary schools selected at random from the National Center for Educational Statistics database. Factors affecting reported start times included…

  4. Factors influencing lopinavir and atazanavir plasma concentration

    PubMed Central

    Stöhr, Wolfgang; Back, David; Dunn, David; Sabin, Caroline; Winston, Alan; Gilson, Richard; Pillay, Deenan; Hill, Teresa; Ainsworth, Jonathan; Gazzard, Brian; Leen, Clifford; Bansi, Loveleen; Fisher, Martin; Orkin, Chloe; Anderson, Jane; Johnson, Margaret; Easterbrook, Philippa; Gibbons, Sara; Khoo, Saye

    2010-01-01

    Background The protease inhibitors lopinavir and atazanavir are both recommended for treatment of HIV-infected patients. Considerable inter-individual variability in plasma concentration has been observed for both drugs. The aim of this study was to evaluate which demographic factors and concomitant drugs are associated with lopinavir and atazanavir plasma concentration. Methods Data from the Liverpool TDM (therapeutic drug monitoring) Registry were linked with the UK Collaborative HIV Cohort (CHIC) study. For each patient, the first measurement of lopinavir (twice daily) or atazanavir [once daily, ritonavir boosted (/r) or unboosted] plasma concentration was included. Linear regression was used to evaluate the association of dose, gender, age, weight, ethnicity and concomitant antiretroviral drugs or rifabutin with log-transformed drug concentration, adjusted for time since last intake. Results Data from 439 patients on lopinavir (69% 400 mg/r, 31% 533 mg/r; 3% concomitant rifabutin) and 313 on atazanavir (60% 300 mg/r, 32% 400 mg/r, 8% 400 mg) were included. Multivariable models revealed the following predictors for lopinavir concentration: weight (11% decrease per additional 10 kg; P = 0.001); dose (25% increase for 533 mg/r; P = 0.024); and rifabutin (116% increase; P < 0.001). For atazanavir the predictors were dose (compared with 300 mg/r: 40% increase for 400 mg/r, 67% decrease for 400 mg; overall P < 0.001) and efavirenz (32% decrease; P = 0.016) but not tenofovir (P = 0.54). Conclusions This analysis confirms that efavirenz decreases atazanavir concentrations, and there was a negative association of weight and lopinavir concentrations. The strong impact of rifabutin on lopinavir concentration should be studied further. PMID:19897506

  5. Factors influencing nursing career choices and choice of study program.

    PubMed

    Haron, Yafa; Reicher, Sima; Riba, Shoshana

    2014-01-01

    In advance of a recruitment campaign, Israeli first-year nursing students of all ethnicities were surveyed to elucidate what factors had influenced them to make nursing their career and what sort of training track they preferred. The responses made it clear that different factors influence different groups differently. There were noticeable differences by gender, age, and ethnicity. Overall, training institutions were chosen for their closeness to the student's home but other factors also operated among particular groups, such as institutional prestige and flexible entry criteria. There was a blatant preference for academic, particularly university-sited, programs over diploma programs.

  6. Factors influencing nursing career choices and choice of study program.

    PubMed

    Haron, Yafa; Reicher, Sima; Riba, Shoshana

    2014-01-01

    In advance of a recruitment campaign, Israeli first-year nursing students of all ethnicities were surveyed to elucidate what factors had influenced them to make nursing their career and what sort of training track they preferred. The responses made it clear that different factors influence different groups differently. There were noticeable differences by gender, age, and ethnicity. Overall, training institutions were chosen for their closeness to the student's home but other factors also operated among particular groups, such as institutional prestige and flexible entry criteria. There was a blatant preference for academic, particularly university-sited, programs over diploma programs. PMID:24878405

  7. Research on the influence of site factors on the expansion of construction land in the Pearl River Delta, China: By using GIS and remote sensing

    NASA Astrophysics Data System (ADS)

    Ye, Yuyao; Zhang, Hongou; Liu, Kai; Wu, Qitao

    2013-04-01

    Landsat TM images of the Pearl River Delta taken in 1988, 1998 and 2006 are used to explore the site factors that influence the construction land expansion in this study. Several site factors, including landscape types and the distances to roads, coastlines, or city centers, had significant impacts on the expansion of construction land, influencing the direction, scale and intensity of the expansion. The site factors serve as important natural and spatial indicators of the preferable locales for construction land expansion, describing tendencies to expand to locations in suburbs, plains and areas near roads or coastlines.

  8. A hypothesis about factors that affect maximum stream temperatures across montane landscapes

    USGS Publications Warehouse

    Isaak, D.J.; Hubert, W.A.

    2001-01-01

    Temperature is an important variable structuring lotic biotas, but little is known about how montane landscapes function to determine stream temperatures. We developed an a priori hypothesis that was used to predict how watershed elements would interact to affect stream temperatures. The hypothesis was tested in a series of path analyses using temperature data from 26 sites on second-order to fourth-order streams across a fifth-order Rocky Mountain watershed. Based on the performance of the first hypothesis, two revised versions of the hypothesis were developed and tested that proved to be more accurate than the original hypothesis. The most plausible of the revised hypotheses accounted for 82 percent of the variation in maximum stream temperature, had a predicted data structure that did not deviate from the empirical data structure, and was the most parsimonious. The final working hypothesis suggested that stream temperature maxima were directly controlled by a large negative effect from mean basin elevation (direct effect = -0.57, p < 0.01) and smaller effects from riparian tree abundance (direct effect = -0.28, p = 0.03), and cattle density (direct effect = 0.24, p = 0.05). Watershed slope, valley constraint, and the abundance of grass across a watershed also affected temperature maxima, but these effects were indirect and mediated through cattle density and riparian trees. Three variables included in the a priori hypothesis - watershed aspect, stream width, and watershed size - had negligible effects on maximum stream temperatures and were omitted from the final working hypothesis.

  9. Modelling highly variable environmental factors to assess potential microbial respiration in complex floodplain landscapes

    PubMed Central

    Tritthart, Michael; Welti, Nina; Bondar-Kunze, Elisabeth; Pinay, Gilles; Hein, Thomas; Habersack, Helmut

    2011-01-01

    The hydrological exchange conditions strongly determine the biogeochemical dynamics in river systems. More specifically, the connectivity of surface waters between main channels and floodplains is directly controlling the delivery of organic matter and nutrients into the floodplains, where biogeochemical processes recycle them with high rates of activity. Hence, an in-depth understanding of the connectivity patterns between main channel and floodplains is important for the modelling of potential gas emissions in floodplain landscapes. A modelling framework that combines steady-state hydrodynamic simulations with long-term discharge hydrographs was developed to calculate water depths as well as statistical probabilities and event durations for every node of a computation mesh being connected to the main river. The modelling framework was applied to two study sites in the floodplains of the Austrian Danube River, East of Vienna. Validation of modelled flood events showed good agreement with gauge readings. Together with measured sediment properties, results of the validated connectivity model were used as basis for a predictive model yielding patterns of potential microbial respiration based on the best fit between characteristics of a number of sampling sites and the corresponding modelled parameters. Hot spots of potential microbial respiration were found in areas of lower connectivity if connected during higher discharges and areas of high water depths.

  10. Human influence on late Holocene fluvial landscape and stratigraphy in the Mixteca Alta of Oaxaca, Mexico

    NASA Astrophysics Data System (ADS)

    Leigh, D. S.; Holdridge, G. H.; Kowalewski, S. A.

    2011-12-01

    The Mixteca Alta of south-central Mexico (state of Oaxaca) is a high-elevation plateau where population and agricultural steadily grew over the past 3000 years, but with a few significant episodes of population decline. Currently, the landscape is highly eroded and gullied in response to widespread land abandonment and diminished population attributed to the Spanish conquest during the 1500s and 1600s. Abandonment apparently resulted in neglect of prehistoric cross-drainage retaining walls, known as lama-bordos, which had been constructed throughout agricultural watersheds for millennia to retain runoff and sediment. Our research seeks to establish the earliest ages for construction of lama-bordos, which are buried by more than 10 m of alluvium in some localities; and we hope to determine if the chronology of alluvial sedimentation is related to fluctuations in population density versus climate changes or other drivers. Sampling is focused on relatively small tributary watersheds (<10 km^2) in the valley of Rio Culebra near the town of Coixlahuaca. Our general hypothesis is counter to Malthusian theory in that we posit land degradation and erosion was punctuated by episodes of population decline when there were insufficient people to maintain the lama-bordo infrastructure. Methods involve: (1) detailed stratigraphic and pedogenic description and sampling of several outcrops; (2) radiocarbon and luminescence dating of stratigraphic sections; (3) geochemical and lithological tracing of sedimentary beds to discriminate time periods of gully erosion; (4) relating the alluvial chronology to archaeological surveys that have established the occupation history of the region. Results indicate that upland gully erosion had occurred prior to widespread human occupation of the area, because >4000 cal yr BP cut-and-fill stratigraphic units commonly contain detritus from upland subsoil and underlying bedrock. We provide numerous radiocarbon dates for the oldest lama-bordos, and

  11. The influence of snowmobile trails on coyote movements during winter in high-elevation landscapes.

    PubMed

    Gese, Eric M; Dowd, Jennifer L B; Aubry, Lise M

    2013-01-01

    Competition between sympatric carnivores has long been of interest to ecologists. Increased understanding of these interactions can be useful for conservation planning. Increased snowmobile traffic on public lands and in habitats used by Canada lynx (Lynx canadensis) remains controversial due to the concern of coyote (Canis latrans) use of snowmobile trails and potential competition with lynx. Determining the variables influencing coyote use of snowmobile trails has been a priority for managers attempting to conserve lynx and their critical habitat. During 2 winters in northwest Wyoming, we backtracked coyotes for 265 km to determine how varying snow characteristics influenced coyote movements; 278 km of random backtracking was conducted simultaneously for comparison. Despite deep snow (>1 m deep), radio-collared coyotes persisted at high elevations (>2,500 m) year-round. All coyotes used snowmobile trails for some portion of their travel. Coyotes used snowmobile trails for 35% of their travel distance (random: 13%) for a mean distance of 149 m (random: 59 m). Coyote use of snowmobile trails increased as snow depth and penetrability off trails increased. Essentially, snow characteristics were most influential on how much time coyotes spent on snowmobile trails. In the early months of winter, snow depth was low, yet the snow column remained dry and the coyotes traveled off trails. As winter progressed and snow depth increased and snow penetrability increased, coyotes spent more travel distance on snowmobile trails. As spring approached, the snow depth remained high but penetrability decreased, hence coyotes traveled less on snowmobile trails because the snow column off trail was more supportive. Additionally, coyotes traveled closer to snowmobile trails than randomly expected and selected shallower snow when traveling off trails. Coyotes also preferred using snowmobile trails to access ungulate kills. Snow compaction from winter recreation influenced coyote

  12. The Influence of Snowmobile Trails on Coyote Movements during Winter in High-Elevation Landscapes

    PubMed Central

    Gese, Eric M.; Dowd, Jennifer L. B.; Aubry, Lise M.

    2013-01-01

    Competition between sympatric carnivores has long been of interest to ecologists. Increased understanding of these interactions can be useful for conservation planning. Increased snowmobile traffic on public lands and in habitats used by Canada lynx (Lynx canadensis) remains controversial due to the concern of coyote (Canis latrans) use of snowmobile trails and potential competition with lynx. Determining the variables influencing coyote use of snowmobile trails has been a priority for managers attempting to conserve lynx and their critical habitat. During 2 winters in northwest Wyoming, we backtracked coyotes for 265 km to determine how varying snow characteristics influenced coyote movements; 278 km of random backtracking was conducted simultaneously for comparison. Despite deep snow (>1 m deep), radio-collared coyotes persisted at high elevations (>2,500 m) year-round. All coyotes used snowmobile trails for some portion of their travel. Coyotes used snowmobile trails for 35% of their travel distance (random: 13%) for a mean distance of 149 m (random: 59 m). Coyote use of snowmobile trails increased as snow depth and penetrability off trails increased. Essentially, snow characteristics were most influential on how much time coyotes spent on snowmobile trails. In the early months of winter, snow depth was low, yet the snow column remained dry and the coyotes traveled off trails. As winter progressed and snow depth increased and snow penetrability increased, coyotes spent more travel distance on snowmobile trails. As spring approached, the snow depth remained high but penetrability decreased, hence coyotes traveled less on snowmobile trails because the snow column off trail was more supportive. Additionally, coyotes traveled closer to snowmobile trails than randomly expected and selected shallower snow when traveling off trails. Coyotes also preferred using snowmobile trails to access ungulate kills. Snow compaction from winter recreation influenced coyote

  13. Wind erosion in semiarid landscapes: Predictive models and remote sensing methods for the influence of vegetation

    NASA Technical Reports Server (NTRS)

    Musick, H. Brad; Truman, C. Randall; Trujillo, Steven M.

    1992-01-01

    Wind erosion in semi-arid regions is a significant problem for which the sheltering effect of rangeland vegetation is poorly understood. Individual plants may be considered as porous roughness elements which absorb or redistribute the wind's momentum. The saltation threshold is the minimum wind velocity at which soil movement begins. The dependence of the saltation threshold on geometrical parameters of a uniform roughness array was studied in a wind tunnel. Both solid and porous elements were used to determine relationships between canopy structure and the threshold velocity for soil transport. The development of a predictive relation for the influence of vegetation canopy structure on wind erosion of soil is discussed.

  14. Why replication is important in landscape genetics: American black bear in the Rocky Mountains

    USGS Publications Warehouse

    Short, Bull R.A.; Cushman, S.A.; MacE, R.; Chilton, T.; Kendall, K.C.; Landguth, E.L.; Schwartz, M.K.; McKelvey, K.; Allendorf, F.W.; Luikart, G.

    2011-01-01

    We investigated how landscape features influence gene flow of black bears by testing the relative support for 36 alternative landscape resistance hypotheses, including isolation by distance (IBD) in each of 12 study areas in the north central U.S. Rocky Mountains. The study areas all contained the same basic elements, but differed in extent of forest fragmentation, altitude, variation in elevation and road coverage. In all but one of the study areas, isolation by landscape resistance was more supported than IBD suggesting gene flow is likely influenced by elevation, forest cover, and roads. However, the landscape features influencing gene flow varied among study areas. Using subsets of loci usually gave models with the very similar landscape features influencing gene flow as with all loci, suggesting the landscape features influencing gene flow were correctly identified. To test if the cause of the variability of supported landscape features in study areas resulted from landscape differences among study areas, we conducted a limiting factor analysis. We found that features were supported in landscape models only when the features were highly variable. This is perhaps not surprising but suggests an important cautionary note - that if landscape features are not found to influence gene flow, researchers should not automatically conclude that the features are unimportant to the species' movement and gene flow. Failure to investigate multiple study areas that have a range of variability in landscape features could cause misleading inferences about which landscape features generally limit gene flow. This could lead to potentially erroneous identification of corridors and barriers if models are transferred between areas with different landscape characteristics. ?? 2011 Blackwell Publishing Ltd.

  15. Why replication is important in landscape genetics: American black bear in the Rocky Mountains.

    PubMed

    Bull, R A Short; Cushman, S A; Mace, R; Chilton, T; Kendall, K C; Landguth, E L; Schwartz, M K; McKelvey, K; Allendorf, Fred W; Luikart, G

    2011-03-01

    We investigated how landscape features influence gene flow of black bears by testing the relative support for 36 alternative landscape resistance hypotheses, including isolation by distance (IBD) in each of 12 study areas in the north central U.S. Rocky Mountains. The study areas all contained the same basic elements, but differed in extent of forest fragmentation, altitude, variation in elevation and road coverage. In all but one of the study areas, isolation by landscape resistance was more supported than IBD suggesting gene flow is likely influenced by elevation, forest cover, and roads. However, the landscape features influencing gene flow varied among study areas. Using subsets of loci usually gave models with the very similar landscape features influencing gene flow as with all loci, suggesting the landscape features influencing gene flow were correctly identified. To test if the cause of the variability of supported landscape features in study areas resulted from landscape differences among study areas, we conducted a limiting factor analysis. We found that features were supported in landscape models only when the features were highly variable. This is perhaps not surprising but suggests an important cautionary note - that if landscape features are not found to influence gene flow, researchers should not automatically conclude that the features are unimportant to the species' movement and gene flow. Failure to investigate multiple study areas that have a range of variability in landscape features could cause misleading inferences about which landscape features generally limit gene flow. This could lead to potentially erroneous identification of corridors and barriers if models are transferred between areas with different landscape characteristics. PMID:21261764

  16. Trophic cascades in agricultural landscapes: indirect effects of landscape composition on crop yield.

    PubMed

    Liere, Heidi; Kim, Tania N; Werling, Benjamin P; Meehan, Timothy D; Landis, Douglas A; Gratton, Claudio

    2015-04-01

    The strength and prevalence of trophic cascades, defined as positive, indirect effects of natural enemies (predatory and parasitic arthropods) on plants, is highly variable in agroecosystems. This variation may in part be due to the spatial or landscape context in which hese trophic cascades occur. In 2011 and 2012, we conducted a natural enemy exclusion experiment in soybean fields along a gradient of landscape composition across southern Wisconsin and Michigan, USA. We used structural equation modeling to ask (1) whether natural enemies influence biocontrol of soybean aphids (SBA) and soybean yield and (2) whether landscape effects on natural enemies influence the strength of the trophic cascades. We found that natural enemies (NE) suppressed aphid populations in both years of our study, and, in 2011, the yield of soybean plants exposed to natural enemies was 37% higher than the yield of plants with aphid populations protected from natural enemies. The strength of the :rophic cascade was also influenced by landscape context. We found that landscapes with a higher proportion of soybean and higher diversity habitats resulted in more NE, fewer aphids, and, in some cases, a trend toward greater soybean yield. These results indicate that landscape context is important for understanding spatial variability in biocontrol and yield, but other factors, such as environmental variability and compensatory growth, might overwhelm the beneficial effects of biocontrol on crop yield. PMID:26214911

  17. Quantifying landscape morphology influence on peatland lateral expansion using ground-penetrating radar (GPR) and peat core analysis

    NASA Astrophysics Data System (ADS)

    Loisel, Julie; Yu, Zicheng; Parsekian, Andrew; Nolan, James; Slater, Lee

    2013-06-01

    peatlands contain vast amounts of organic carbon. Large-scale datasets have documented spatial patterns of peatland initiation as well as vertical peat accumulation rates. However, the rate, pattern, and timing of lateral expansion across the northern landscape remain largely unknown. As peatland lateral extent is a key boundary condition constraining the dynamics of peatland systems, understanding this process is essential. Here we use ground penetrating radar (GPR) and peat core analysis to study the effect of local slope and topography on peatland development at a site in south-central Alaska. The study site is unique in that a thick tephra (volcanic ash) layer, visible in the GPR data, interrupted the peatland development for about one thousand years during the mid Holocene. In our analysis, this tephra layer serves as a re-initiation point for peatland development. By comparing the initial mineral basin vs. the post-tephra surfaces, the influence of topography and slope on peatland expansion rate and peat-carbon sequestration was analyzed. Our results show that (1) peatland surface slope becomes progressively shallower over the Holocene, (2) slope affects peatland lateral expansion nonlinearly, (3) the relationship between lateral expansion rate and slope follows a power-law behavior, and (4) peatland expansion becomes slope-limited above a threshold (0.5°). Furthermore, we propose a conceptual model linking slope to peatland lateral expansion where slope gradient and basin topography exert deterministic controls on peatland lateral expansion directly or through hydrology and vertical accumulation rates.

  18. Interactions between natural-occurring landscape conditions and land use influencing the abundance of riverine smallmouth bass, micropterus dolomieu

    USGS Publications Warehouse

    Brewer, S.K.; Rabeni, C.F.

    2011-01-01

    This study examined how interactions between natural landscape features and land use influenced the abundance of smallmouth bass, Micropterus dolomieu, in Missouri, USA, streams. Stream segments were placed into one of four groups based on natural-occurring watershed characteristics (soil texture and soil permeability) predicted to relate to smallmouth bass abundance. Within each group, stream segments were assigned forest (n = 3), pasture (n = 3), or urban (n = 3) designations based on the percentages of land use within each watershed. Analyses of variance indicated smallmouth bass densities differed between land use and natural conditions. Decision tree models indicated abundance was highest in forested stream segments and lowest in urban stream segments, regardless of group designation. Land use explained the most variation in decision tree models, but in-channel features of temperature, flow, and sediment also contributed significantly. These results are unique and indicate the importance of natural-occurring watershed conditions in defining the potential of populations and how finer-scale filters interact with land use to further alter population potential. Smallmouth bass has differing vulnerabilities to land-use attributes, and the better the natural watershed conditions are for population success, the more resilient these populations will be when land conversion occurs.

  19. Roads influence movement and home ranges of a fragmentation-sensitive carnivore, the bobcat, in an urban landscape

    USGS Publications Warehouse

    Poessel, Sharon A; Boydston, Erin E.; Lyren, Lisa M.; Fisher, Robert N.; Burdett, Christopher L.; Alonso, Robert S.; Crooks, Kevin R.

    2014-01-01

    Roads in urbanized areas can impact carnivore populations by constraining their movements and increasing mortality. Bobcats (Lynx rufus) are felids capable of living in urban environments, but are sensitive to habitat fragmentation and, thus, useful indicators of landscape connectivity; in particular, bobcat habitat selection, movement, and mortality may be affected by roads. We analyzed movement patterns of 52 bobcats in southern California in three study sites and investigated: (1) how bobcats responded to two types of roads within their home ranges; (2) how they placed their home ranges with respect to roads within the study area; and (3) whether male and female bobcats differed in their behavioral responses to roads. Within home ranges, primary and secondary roads did not influence movements, but bobcats more frequently crossed secondary roads when road densities were higher within their home ranges, thus increasing mortality risk. However, road densities within each study site were several times higher than road densities within home ranges, suggesting bobcats selected against roaded areas in home-range placement. Male home ranges bordering roads were smaller than home ranges for other males, but male home ranges containing roads were larger than those without roads. Male bobcats also were more likely to cross roads than females, potentially reflecting larger male home range sizes. Our results suggest roads have important impacts on urban bobcats, with stronger effects on males than females, and continued efforts to mitigate the effects of roads on carnivores and other fragmentation-sensitive species would help promote connectivity conservation in urban systems.

  20. Critical factors and paths influencing construction workers' safety risk tolerances.

    PubMed

    Wang, Jiayuan; Zou, Patrick X W; Li, Penny P

    2016-08-01

    While workers' safety risk tolerances have been regarded as a main reason for their unsafe behaviors, little is known about why different people have different risk tolerances even when confronting the same situation. The aim of this research is to identify the critical factors and paths that influence workers' safety risk tolerance and to explore how they contribute to accident causal model from a system thinking perceptive. A number of methods were carried out to analyze the data collected through interviews and questionnaire surveys. In the first and second steps of the research, factor identification, factor ranking and factor analysis were carried out, and the results show that workers' safety risk tolerance can be influenced by four groups of factors, namely: (1) personal subjective perception; (2) work knowledge and experiences; (3) work characteristics; and (4) safety management. In the third step of the research, hypothetical influencing path model was developed and tested by using structural equation modeling (SEM). It is found that the effects of external factors (safety management and work characteristics) on risk tolerance are larger than that of internal factors (personal subjective perception and work knowledge & experiences). Specifically, safety management contributes the most to workers' safety risk tolerance through its direct effect and indirect effect; while personal subjective perception comes the second and can act as an intermedia for work characteristics. This research provides an in-depth insight of workers' unsafe behaviors by depicting the contributing factors as shown in the accident causal model developed in this research. PMID:26775077

  1. Critical factors and paths influencing construction workers' safety risk tolerances.

    PubMed

    Wang, Jiayuan; Zou, Patrick X W; Li, Penny P

    2016-08-01

    While workers' safety risk tolerances have been regarded as a main reason for their unsafe behaviors, little is known about why different people have different risk tolerances even when confronting the same situation. The aim of this research is to identify the critical factors and paths that influence workers' safety risk tolerance and to explore how they contribute to accident causal model from a system thinking perceptive. A number of methods were carried out to analyze the data collected through interviews and questionnaire surveys. In the first and second steps of the research, factor identification, factor ranking and factor analysis were carried out, and the results show that workers' safety risk tolerance can be influenced by four groups of factors, namely: (1) personal subjective perception; (2) work knowledge and experiences; (3) work characteristics; and (4) safety management. In the third step of the research, hypothetical influencing path model was developed and tested by using structural equation modeling (SEM). It is found that the effects of external factors (safety management and work characteristics) on risk tolerance are larger than that of internal factors (personal subjective perception and work knowledge & experiences). Specifically, safety management contributes the most to workers' safety risk tolerance through its direct effect and indirect effect; while personal subjective perception comes the second and can act as an intermedia for work characteristics. This research provides an in-depth insight of workers' unsafe behaviors by depicting the contributing factors as shown in the accident causal model developed in this research.

  2. Probing the kinetic landscape of Hox transcription factor-DNA binding in live cells by massively parallel Fluorescence Correlation Spectroscopy.

    PubMed

    Papadopoulos, Dimitrios K; Krmpot, Aleksandar J; Nikolić, Stanko N; Krautz, Robert; Terenius, Lars; Tomancak, Pavel; Rigler, Rudolf; Gehring, Walter J; Vukojević, Vladana

    2015-11-01

    Hox genes encode transcription factors that control the formation of body structures, segment-specifically along the anterior-posterior axis of metazoans. Hox transcription factors bind nuclear DNA pervasively and regulate a plethora of target genes, deploying various molecular mechanisms that depend on the developmental and cellular context. To analyze quantitatively the dynamics of their DNA-binding behavior we have used confocal laser scanning microscopy (CLSM), single-point fluorescence correlation spectroscopy (FCS), fluorescence cross-correlation spectroscopy (FCCS) and bimolecular fluorescence complementation (BiFC). We show that the Hox transcription factor Sex combs reduced (Scr) forms dimers that strongly associate with its specific fork head binding site (fkh250) in live salivary gland cell nuclei. In contrast, dimers of a constitutively inactive, phospho-mimicking variant of Scr show weak, non-specific DNA-binding. Our studies reveal that nuclear dynamics of Scr is complex, exhibiting a changing landscape of interactions that is difficult to characterize by probing one point at a time. Therefore, we also provide mechanistic evidence using massively parallel FCS (mpFCS). We found that Scr dimers are predominantly formed on the DNA and are equally abundant at the chromosomes and an introduced multimeric fkh250 binding-site, indicating different mobilities, presumably reflecting transient binding with different affinities on the DNA. Our proof-of-principle results emphasize the advantages of mpFCS for quantitative characterization of fast dynamic processes in live cells.

  3. Human-caused mortality influences spatial population dynamics: pumas in landscapes with varying mortality risks

    USGS Publications Warehouse

    Newby, Jesse R.; Mills, L. Scott; Ruth, Toni K.; Pletscher, Daniel H.; Mitchell, Michael S.; Quigley, Howard B.; Murphy, Kerry M.; DeSimone, Rich

    2013-01-01

    An understanding of how stressors affect dispersal attributes and the contribution of local populations to multi-population dynamics are of immediate value to basic and applied ecology. Puma (Puma concolor) populations are expected to be influenced by inter-population movements and susceptible to human-induced source–sink dynamics. Using long-term datasets we quantified the contribution of two puma populations to operationally define them as sources or sinks. The puma population in the Northern Greater Yellowstone Ecosystem (NGYE) was largely insulated from human-induced mortality by Yellowstone National Park. Pumas in the western Montana Garnet Mountain system were exposed to greater human-induced mortality, which changed over the study due to the closure of a 915 km2 area to hunting. The NGYE’s population growth depended on inter-population movements, as did its ability to act as a source to the larger region. The heavily hunted Garnet area was a sink with a declining population until the hunting closure, after which it became a source with positive intrinsic growth and a 16× increase in emigration. We also examined the spatial and temporal characteristics of individual dispersal attributes (emigration, dispersal distance, establishment success) of subadult pumas (N = 126). Human-caused mortality was found to negatively impact all three dispersal components. Our results demonstrate the influence of human-induced mortality on not only within population vital rates, but also inter-population vital rates, affecting the magnitude and mechanisms of local population’s contribution to the larger metapopulation.

  4. The Application of GIS 3D Modeling and Analysis Technology in Real Estate Mass Appraisal - Taking landscape and sunlight factors as the example

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Li, Y.; Liu, B.; Liu, C.

    2014-04-01

    Based on procedural modeling approach and buildings 2D GIS data of Shenzhen, 3D external models of buildings are generated by CityEngine in a quick and batch mode. And 3D internal model is generated by vectorization of houses distribution within the target building. Following that, the landscape analysis and the sunlight analysis based on GIS visibility analysis method are applied on 3D model of the target building to get the concrete quantization indexes, such as landscape visual range and sunshine duration which could significantly influence real estate value. Finally, the drawing with 3D visualization effect for landscape information and sunshine information is produced. Compared with traditional manual modeling method, the results showed that rule-based 3D modeling method in CityEngine platform could take full advantage of existing GIS data. It could improve the efficiency of 3D modeling by rapidly and automatically generate refined building 3D models in batch mode. Meanwhile, compared with man-made subjective judgment, the building landscape and sunlight analysis model built by visibility analysis could quantify landscape and sunshine indexes more accurately. Furthermore, the application in real estate mass appraisal model for calculation and analysis will reduce the index errors caused by man-made subjective judgment. In addition, precise 3D visualization effect can provide appraisers with more intuitive and efficient view for real estate expression. It greatly improves the efficiency and accuracy in real estate appraisal.

  5. Factors Influencing the Intended Likelihood of Exposing Sexual Infidelity.

    PubMed

    Kruger, Daniel J; Fisher, Maryanne L; Fitzgerald, Carey J

    2015-08-01

    There is a considerable body of literature on infidelity within romantic relationships. However, there is a gap in the scientific literature on factors influencing the likelihood of uninvolved individuals exposing sexual infidelity. Therefore, we devised an exploratory study examining a wide range of potentially relevant factors. Based in part on evolutionary theory, we anticipated nine potential domains or types of influences on the likelihoods of exposing or protecting cheaters, including kinship, strong social alliances, financial support, previous relationship behaviors (including infidelity and abuse), potential relationship transitions, stronger sexual and emotional aspects of the extra-pair relationship, and disease risk. The pattern of results supported these predictions (N = 159 men, 328 women). In addition, there appeared to be a small positive bias for participants to report infidelity when provided with any additional information about the situation. Overall, this study contributes a broad initial description of factors influencing the predicted likelihood of exposing sexual infidelity and encourages further studies in this area.

  6. An Early Pennsylvanian threshold for the influence of vegetation on fluvial landscapes, based on the geological record of Atlantic Canada

    NASA Astrophysics Data System (ADS)

    Gibling, Martin; Ielpi, Alessandro; Bashforth, Arden; Davies, Neil

    2015-04-01

    Vegetation profoundly influences modern fluvial systems, depending on plant life-history strategies, tolerance to disturbance, and habitat drainage. However, direct evidence for these dynamic relationships is cryptic and has commonly been overlooked in ancient deposits. We report evidence for profound interactions between channels, in situ and transported vegetation in Lower Pennsylvanian formations of Atlantic Canada (~310 Ma), attributed to braided, meandering and fixed-channel (anastomosing) systems. Plant groups include lycopsids that preferred stable wetland settings, disturbance-tolerant calamitaleans, and deeply rooted cordaitaleans (early gymnosperms) that originated in the late Mississippian and colonised both wetland and dryland settings. For the meandering and anastomosing channel deposits, upright vegetation was observed within channel-based bedforms and bars and on channel margins. Lycopsids and calamitalean groves colonized the channel bed and bank-attached bars during periods of reduced flow, nucleating bar growth after flow resumed. Upright lycopsids and cordaitaleans are common along channel cutbanks and are locally tilted towards the channel, implying involvement in bank stabilization. Rhizoconcretions that formed around deep cordaitalean roots may have aided bank reinforcement. Tetrapod and arthropod trackways in the channel deposits indicate a close linkage between riparian and aquatic ecosystems. In the braided systems, sediments that contain abundant cordaitalean logs constitute nearly 20% of channel deposits, and the logs form channel-base lags, fill channels up to 6 m deep, and form nuclei for shallow sandbars. Log accumulations overlain by shale lenses imply a contribution to channel avulsion. Rooted channel-sandstones containing upright trees are interpreted as vegetated islands in an island-braided system. Anastomosing systems are abundant in these Lower Pennsylvanian formations but rare in older strata, and the multi-channel island

  7. Landscape response to deglaciation in a high relief, monsoon-influenced alpine environment, Langtang Himal, Nepal

    USGS Publications Warehouse

    Barnard, P.L.; Owen, L.A.; Finkel, R.C.; Asahi, K.

    2006-01-01

    Significant glacial fluctuations and rapid paraglacial reworking of glacigenic sediments characterize the Middle and Late Holocene of the Langtang Khola Valley, Central Nepal Himalaya. Geomorphic mapping and beryllium-10 cosmogenic radionuclide (CRN) dating of moraines and paraglacial fans were undertaken to test the existing paraglacial fan, terrace and moraine chronologies. The new dating compares favorably with prior studies that utilized radiocarbon, adding additional support to the assumption that fan and terrace formation are strongly linked to deglaciation. Fan and terrace denudation rates are so rapid in this region, averaging ∼33 mm/yr, that no depositional landforms older than 5 ka are preserved within 250 m of the valley floor. In this region, high rates of denudation during the Late Quaternary are driven by a combination of rapid tectonic uplift, numerous glacial fluctuations and intense weathering driven by an active monsoon climate. Extensive reworking of glacigenic sediments in Langtang during the latter half of the Holocene is consistent with studies completed in other areas of the Himalaya that are strongly influenced by the monsoon.

  8. Estimating Carcass Persistence and Scavenging Bias in a Human Influenced Landscape

    USGS Publications Warehouse

    Flint, Paul L.; Lance, Ellen W.; Sowl, Kristine M.; Donnelly, Tyrone F.

    2010-01-01

    We examined variation in persistence rates of waterfowl carcasses placed along a series of transects in tundra habitats in western Alaska. This study was designed to assess the effects of existing tower structures and was replicated with separate trials in winter, summer and fall as both the resident avian population and the suite of potential scavengers varied seasonally. Carcass persistence rates were uniformly low, with <50% of carcasses persisting for more than a day on average. Persistence rate varied by carcass age, carcass size, among transects and was lowest in the fall and highest in the summer. We found little support for models where persistence varied in relation to the presence of tower structures. We interpret this as evidence that scavengers were not habituated to searching for carcasses near these structures. Our data demonstrate that only a small fraction of bird carcasses are likely to persist between searches, and if not appropriately accounted for, scavenging bias could significantly influence bird mortality estimates. The variation that we documented suggests that persistence rates should not be extrapolated among tower locations or across time periods as the variation in carcass persistence will result in biased estimates of total bird strike mortality.

  9. Large-scale spatial variation in parasite communities influenced by anthropogenic factors.

    PubMed

    Altman, Irit; Byers, James E

    2014-07-01

    Parasites are integral members of natural communities, but large-scale determinants of their abundance and diversity, including the importance of biotic and abiotic factors, both natural and anthropogenic, are often not well understood. Here, we examine which factors best predict larval trematode communities in the mudsnail host Ilyanassa obsoleta across a regional landscape. At 15 salt marsh sites spanning 200 km, we quantified the diversity of trematodes and the prevalence (i.e., proportion) of infected hosts and sampled a broad array of potential parasite predictors including abundance of intermediate and definitive hosts, habitat, nutrients, metals, roads, and sediment characteristics. We identified the set of best performing models to explain variability associated with five metrics of trematode prevalence and diversity using an information-theoretic approach. Results indicate that several anthropogenic factors associate with this trematode community and that the direction of their influence differs. Road density around sites was a strong negative predictor of all trematode prevalence and species richness metrics. Nitrogen, another human influenced variable, was a strong positive predictor for the most abundant trematode species in the system. In addition, the abundance of definitive fish hosts was a positive predictor in several models, confirming the importance of this direct biological link to parasites. Other influential variables included sediment composition and heavy metals (arsenic, copper, lead, and zinc). We discuss possible direct and indirect mechanisms to explain these findings including that anthropogenic factors may be directly influencing free-living stages of trematodes, or be acting as proxies of hard-to-measure hosts. PMID:25163120

  10. Large-scale spatial variation in parasite communities influenced by anthropogenic factors.

    PubMed

    Altman, Irit; Byers, James E

    2014-07-01

    Parasites are integral members of natural communities, but large-scale determinants of their abundance and diversity, including the importance of biotic and abiotic factors, both natural and anthropogenic, are often not well understood. Here, we examine which factors best predict larval trematode communities in the mudsnail host Ilyanassa obsoleta across a regional landscape. At 15 salt marsh sites spanning 200 km, we quantified the diversity of trematodes and the prevalence (i.e., proportion) of infected hosts and sampled a broad array of potential parasite predictors including abundance of intermediate and definitive hosts, habitat, nutrients, metals, roads, and sediment characteristics. We identified the set of best performing models to explain variability associated with five metrics of trematode prevalence and diversity using an information-theoretic approach. Results indicate that several anthropogenic factors associate with this trematode community and that the direction of their influence differs. Road density around sites was a strong negative predictor of all trematode prevalence and species richness metrics. Nitrogen, another human influenced variable, was a strong positive predictor for the most abundant trematode species in the system. In addition, the abundance of definitive fish hosts was a positive predictor in several models, confirming the importance of this direct biological link to parasites. Other influential variables included sediment composition and heavy metals (arsenic, copper, lead, and zinc). We discuss possible direct and indirect mechanisms to explain these findings including that anthropogenic factors may be directly influencing free-living stages of trematodes, or be acting as proxies of hard-to-measure hosts.

  11. Landscape level influence: aquatic primary production in the Colorado River of Glen and Grand canyons

    NASA Astrophysics Data System (ADS)

    Yard, M. D.; Kennedy, T.; Yackulic, C. B.; Bennett, G. E.

    2012-12-01

    Irregular features common to canyon-bound regions intercept solar incidence (photosynthetic photon flux density [PPFD: μmol m-2 s-1]) and can affect ecosystem energetics. The Colorado River in Grand Canyon is topographically complex, typical of most streams and rivers in the arid southwest. Dam-regulated systems like the Colorado River have reduced sediment loads, and consequently increased water transparency relative to unimpounded rivers; however, sediment supply from tributaries and flow regulation that affects erosion and subsequent sediment transport, interact to create spatial and temporal variation in optical conditions in this river network. Solar incidence and suspended sediment loads regulate the amount of underwater light available for aquatic photosynthesis in this regulated river. Since light availability is depth dependent (Beer's law), benthic algae is often exposed to varying levels of desiccation or reduced light conditions due to daily flow regulation, additional factors that further constrain aquatic primary production. Considerable evidence suggests that the Colorado River food web is now energetically dependent on autotrophic production, an unusual condition since large river foodwebs are typically supported by allochthonous carbon synthesized and transported from terrestrial environments. We developed a mechanistic model to account for these regulating factors to predict how primary production might be affected by observed and alternative flow regimes proposed as part of ongoing adaptive management experimentation. Inputs to our model include empirical data (suspended sediment and temperature), and predictive relationships: 1) solar incidence reaching the water surface (topographic complexity), 2) suspended sediment-light extinction relationships (optical properties), 3) unsteady flow routing model (stage-depth relationship), 4) channel morphology (photosynthetic area), and 5) photosynthetic-irradiant response for dominant algae (Cladophora

  12. [Responses of alpine grassland landscape in the source region of Shule River Basin to topographical factors and frozen ground types].

    PubMed

    Chen, Jian-Jun; Yi, Shu-Hua; Qin, Yu; Wang, Xiao-Yun

    2014-06-01

    This paper retrieved the fractional vegetation cover of alpine grassland in the source region of the Shule River Basin based on Chinese environmental satellite (HJ-1A/1B) images and field data, and analyzed the response of the vegetation cover to topographic factors and types of frozen ground. The results showed that the vegetation coverage of this region was low with large spatial heterogeneity and high degree of dispersion. The landscape consisted mainly of non-vegetation surface types, eg. ice, snow, the bare rock gravel land and bare land. Slopes and aspects were the main limiting factors of vegetation distribution. The average vegetation coverage decreased with the increase of slope. The average vegetation coverage was the lowest on the sunny slope, and the highest on the shady slope. There were significant differences of vegetation coverage among different types of frozen ground. The distribution of vegetation coverage presented a reversed "U" curve trend by extremely stable permafrost, stable permafrost, sub-stable permafrost, transition permafrost, unstable permafrost and seasonal frost, and the average vegetation coverage was the highest in the sub-stable permafrost.

  13. Watershed Influences on Residence Time and Oxygen Reduction Rates in an Agricultural Landscape

    NASA Astrophysics Data System (ADS)

    Shope, C. L.; Tesoriero, A. J.

    2015-12-01

    Agricultural use of synthetic fertilizers and animal manure has led to increased crop production, but also elevated nitrogen concentrations in groundwater, resulting in impaired water quality. Groundwater oxygen concentrations are a key indicator of potential biogeochemical processes, which control water/aquifer interactions and contaminant transport. The U.S. Geological Survey's National Water-Quality Assessment Program has a long-history of studying nutrient transport and processing across the United States and the Glacial Aquifer system in particular. A series of groundwater well networks in Eastern Wisconsin is being used to evaluate the distribution of redox reaction rates over a range of scales with a focus on dissolved O2 reduction rates. An analysis of these multi-scale networks elucidates the influence of explanatory variables (i.e.: soil type, land use classification) on reduction rates and redox reactions throughout the Fox-Wolf-Peshtigo watersheds. Multiple tracers including dissolved gasses, tritium, helium, chlorofluorocarbons, sulfur hexafluoride, and carbon-14 were used to estimate groundwater ages (0.8 to 61.2 yr) at over 300 locations. Our results indicate O2 reduction rates along a flowpath study area (1.2 km2) of 0.15 mg O2 L-1 yr-1 (0.12 to 0.18 mg O2 L-1 yr-1) up to 0.41 mg O2 L-1 yr-1 (0.23 to 0.89 mg O2 L-1 yr-1) for a larger scale land use study area (3,300 km2). Preliminary explanatory variables that can be used to describe the variability in reduction rates include soil type (hydrologic group, bulk density) and chemical concentrations (nitrite plus nitrate, silica). The median residence time expected to reach suboxic conditions (≤ 0.4 mg O2 L-1) for the flowpath and the land use study areas was 66 and 25 yr, respectively. These results can be used to elucidate and differentiate the impact of residence time on groundwater quality vulnerability and sustainability in agricultural regions without complex flow models.

  14. Habitat factors influencing distributions of Anaplasma phagocytophilum and Ehrlichia chaffeensis in the Mississippi Alluvial Valley.

    PubMed

    Manangan, J S; Schweitzer, S H; Nibbelink, N; Yabsley, M J; Gibbs, S E J; Wimberly, M C

    2007-01-01

    Human monocytotropic ehrlichiosis (HME), caused by the bacterium Ehrlichia chaffeensis, and human granulocytic anaplasmosis (HGA), caused by the bacterium Anaplasma phagocytophilum, are two emerging tick-borne zoonoses of concern. Factors influencing geographic distributions of these pathogens are not fully understood, especially at varying spatial extents (regional versus landscape) and resolutions (counties versus smaller land units). We used logistic regression to compare influences of physical environment, land cover composition, and landscape heterogeneity on distributions of A. phagocytophilum and E. chaffeensis at multiple spatial extents. Pathogen presence or absence was determined from white-tailed deer (Odocoileus virginianus) serum samples collected from 1981 to 2005. Ecological predictor variables were derived from spatial datasets that represented deer density, elevation, land cover, normalized difference vegetation index (NDVI), hydrology, and soil moisture. We used three strategies (a priori, exploratory, and spatial extent) to develop models. Best fitting models were applied within a geographic information system to create predictive probability surfaces for each bacterium. Ecological predictor variables generally resulted in better fitting models for E. chaffeensis than A. phagocytophilum (90.5% and 68% sensitivity, respectively), possibly as a result of differences in the natural histories of tick vectors. Although alternative model development strategies produced different models, in all cases bacteria presence or absence was affected by a combination of soil moisture or flooding variables (thought to affect primarily tick vectors) and forest cover or NDVI variables (thought to affect primarily mammalian hosts). This research demonstrates the potential for modeling the distributions of microscopic tick-borne pathogens using coarse regional datasets and emphasizes the importance of forest cover and flooding as environmental constraints, as well as

  15. The influence of hydrogeomorphic dynamics on fish habitat: A case study using the ooCAESAR landscape evolution model

    NASA Astrophysics Data System (ADS)

    Wheaton, J. M.; Sear, D. A.; Darby, S. E.; Booker, D. E.; Acreman, M.

    2005-12-01

    The sediments, morphological features and riverflows that define the hydrogeomorphology of natural river channels provide physical habitat diversity that sustains the aquatic biodiversity of river ecosystems. This simple concept underpins the large number of contemporary ecohydraulic models that are available in the literature. Such models have been widely used to predict how morphological diversity (taken here to encompass channel sediments, topography and flow velocity) influences habitat quality for target species at the reach scale. The accuracy of these predictions is a matter of considerable practical importance, as the results are frequently used as the basis for restoration or rehabilitation. However, such models are limited in that they do not account for dynamic changes in river morphology, which themselves are triggered by changes in the flows of water and sediment delivered from the watershed upstream and stimulated by climatic, tectonic or land cover perturbations across a wide range of temporal scales. Accordingly there is an urgent need to combine the outputs of catchment-based geomorphological models with ecohydraulic models, so that predictions of habitat quality focused on specific reaches can be placed into their appropriate (i.e., the watershed) spatial context. To address these issues we herein present preliminary simulations from a case study of the Sulphur Creek watershed, a 24.2 sq. km., third-order catchment draining one of 47 tributaries to the Napa River, which empties southerly into the San Francisco Bay of northern California. Therein, the influence of catchment-scale geomorphic dynamics on reach-scale fish habitat is investigated using the ooCAESAR landscape evolution model. This cellular automaton model, based on its predecessor CAESAR, was chosen because it can be run at spatial resolutions (1 to 5 m.) that are ecologically meaningful and at temporal resolutions that capture both individual event dynamics and long-term evolutionary

  16. Resources or landmarks: which factors drive homing success in Tetragonula carbonaria foraging in natural and disturbed landscapes?

    PubMed

    Leonhardt, Sara D; Kaluza, Benjamin F; Wallace, Helen; Heard, Tim A

    2016-10-01

    To date, no study has investigated how landscape structural (visual) alterations affect navigation and thus homing success in stingless bees. We addressed this question in the Australian stingless bee Tetragonula carbonaria by performing marking, release and re-capture experiments in landscapes differing in habitat homogeneity (i.e., the proportion of elongated ground features typically considered prominent visual landmarks). We investigated how landscape affected the proportion of bees and nectar foragers returning to their hives as well as the earliest time bees and foragers returned. Undisturbed landscapes with few landmarks (that are conspicuous to the human eye) and large proportions of vegetation cover (natural forests) were classified visually/structurally homogeneous, and disturbed landscapes with many landmarks and fragmented or no extensive vegetation cover (gardens and plantations) visually/structurally heterogeneous. We found that proportions of successfully returning nectar foragers and earliest times first bees and foragers returned did not differ between landscapes. However, most bees returned in the visually/structurally most (forest) and least (garden) homogeneous landscape, suggesting that they use other than elongated ground features for navigation and that return speed is primarily driven by resource availability in a landscape. PMID:27311817

  17. Resources or landmarks: which factors drive homing success in Tetragonula carbonaria foraging in natural and disturbed landscapes?

    PubMed

    Leonhardt, Sara D; Kaluza, Benjamin F; Wallace, Helen; Heard, Tim A

    2016-10-01

    To date, no study has investigated how landscape structural (visual) alterations affect navigation and thus homing success in stingless bees. We addressed this question in the Australian stingless bee Tetragonula carbonaria by performing marking, release and re-capture experiments in landscapes differing in habitat homogeneity (i.e., the proportion of elongated ground features typically considered prominent visual landmarks). We investigated how landscape affected the proportion of bees and nectar foragers returning to their hives as well as the earliest time bees and foragers returned. Undisturbed landscapes with few landmarks (that are conspicuous to the human eye) and large proportions of vegetation cover (natural forests) were classified visually/structurally homogeneous, and disturbed landscapes with many landmarks and fragmented or no extensive vegetation cover (gardens and plantations) visually/structurally heterogeneous. We found that proportions of successfully returning nectar foragers and earliest times first bees and foragers returned did not differ between landscapes. However, most bees returned in the visually/structurally most (forest) and least (garden) homogeneous landscape, suggesting that they use other than elongated ground features for navigation and that return speed is primarily driven by resource availability in a landscape.

  18. External and Internal Factors Influencing Happiness in Elite Collegiate Athletes

    ERIC Educational Resources Information Center

    Denny, Katherine G.; Steiner, Hans

    2009-01-01

    When under conditions of high demand and allostatic load, are happiness and satisfaction in four domains (family, friends, academics, recreation) influenced more by external or internal factors? Do student-athletes who lead exceedingly complicated lives report happiness as a function of athletic achievement or internal disposition? Stanford…

  19. Computer Visualizations: Factors that Influence Spatial Anatomy Comprehension

    ERIC Educational Resources Information Center

    Nguyen, Ngan; Nelson, Andrew J.; Wilson, Timothy D.

    2012-01-01

    Computer visualizations are increasingly common in education across a range of subject disciplines, including anatomy. Despite optimism about their educational potential, students sometime have difficulty learning from these visualizations. The purpose of this study was to explore a range of factors that influence spatial anatomy comprehension…

  20. Factors Influencing Faculty Engagement--Then, Now, and Future

    ERIC Educational Resources Information Center

    Holland, Barbara A.

    2016-01-01

    In this commentary, author Barbara Holland reflects on her 1999 "Journal of Public Service & Outreach" article, "Factors and Strategies That Influence Faculty Involvement in Public Service" (EJ589785) reprinted in this 20th anniversary issue of "Journal of Higher Education Outreach and Engagement." In the late…

  1. Factors Influencing Consent to Having Videotaped Mental Health Sessions

    ERIC Educational Resources Information Center

    Ko, Kenton; Goebert, Deborah

    2011-01-01

    Objective: The authors critically reviewed the literature regarding factors influencing consent to having videotaped mental health sessions. Methods: The authors searched the literature in PubMed, PsycINFO, Google Scholar, and Web of Science from the mid-1950s through February 2009. Results: The authors identified 27 studies, of which 19 (73%)…

  2. Factors Influencing Exemplary Science Teachers' Levels of Computer Use

    ERIC Educational Resources Information Center

    Hakverdi, Meral; Dana, Thomas M.; Swain, Colleen

    2011-01-01

    The purpose of this study was to examine exemplary science teachers' use of technology in science instruction, factors influencing their level of computer use, their level of knowledge/skills in using specific computer applications for science instruction, their use of computer-related applications/tools during their instruction, and their…

  3. Information Booklets about Cancer: Factors Influencing Patient Satisfaction and Utilisation.

    ERIC Educational Resources Information Center

    Butow, Phyllis; Brindle, Elizabeth; McConnell, David; Boakes, Robert; Tattersall, Martin

    1998-01-01

    Explored factors influencing patient satisfaction with and utilization of information booklets. Patients (N=36) rated five booklets, and strongly preferred one with a grade-eight reading level. The relationship of preference and recall was investigated. No difference between those who seek or avoid information was found. Additional findings are…

  4. Investigating Factors that Influence Item Performance on ACS Exams

    ERIC Educational Resources Information Center

    Schroeder, Jacob; Murphy, Kristen L.; Holme, Thomas A.

    2012-01-01

    General chemistry tests from the Examinations Institute of the Division of Chemical Education of the American Chemical Society have been analyzed to identify factors that may influence how individual test items perform. In this paper, issues of item order (position within a set of items that comprise a test) and answer order (position of correct…

  5. Factors Influencing Teachers' Engagement in Informal Learning Activities

    ERIC Educational Resources Information Center

    Lohman, Margaret C.

    2006-01-01

    Purpose: The purpose of this study is to examine factors influencing the engagement of public school teachers in informal learning activities. Design/methodology/approach: This study used a survey research design. Findings: Analysis of the data found that teachers rely to a greater degree on interactive than on independent informal learning…

  6. Environmental Volunteers: Factors Influencing Their Involvement in Environmental Action

    ERIC Educational Resources Information Center

    Liarakou, Georgia; Kostelou, Eleni; Gavrilakis, Costas

    2011-01-01

    The aim of the present study was to investigate the factors that influence volunteers to become involved in environmental action. The research focused on volunteers undertaking action in summer camps organised by an environmental non-governmental organisation (NGO) in Greece. The results suggest that the environmental issues addressed in volunteer…

  7. Factors that Influence Women's Technical Skill Development in Outdoor Adventure

    ERIC Educational Resources Information Center

    Warren, Karen; Loeffler, TA

    2006-01-01

    This article provides a theoretical foundation for understanding women's technical skill development (TSD) in outdoor adventure. An examination of societal and biological factors influencing women's TSD focuses on gender role socialization, sense of competence, technical conditioning, sexism, spatial ability, and risk-taking. The article suggests…

  8. Factors Influencing Student Participation in College Study Abroad Programs

    ERIC Educational Resources Information Center

    Bandyopadhyay, Soumava; Bandyopadhyay, Kakoli

    2015-01-01

    This paper proposes a theoretical framework to investigate the factors that influence student participation in college study abroad programs. The authors posit that students' general perceptions regarding the study abroad experience and their expectations of intercultural awareness from study abroad programs will impact their perceptions of…

  9. Analysis on Influence Factors of Adaptive Filter Acting on ANC

    NASA Astrophysics Data System (ADS)

    Zhang, Xiuqun; Zou, Liang; Ni, Guangkui; Wang, Xiaojun; Han, Tao; Zhao, Quanfu

    The noise problem has become more and more serious in recent years. The adaptive filter theory which is applied in ANC [1] (active noise control) has also attracted more and more attention. In this article, the basic principle and algorithm of adaptive theory are both researched. And then the influence factor that affects its covergence rate and noise reduction is also simulated.

  10. Factors that Influence Informal Learning in the Workplace

    ERIC Educational Resources Information Center

    Berg, Shelley A.; Chyung, Seung Youn

    2008-01-01

    Purpose: The purpose of this research is to investigate factors that influence informal learning in the workplace and the types of informal learning activities people engage in at work. More specifically, the research examined: the relationship between informal learning engagement and the presence of learning organization characteristics; and…

  11. Factors Influencing Federal Employee Worker Satisfaction: A Baseline Study.

    ERIC Educational Resources Information Center

    Schmidt, Wallace V.; And Others

    Utilizing data from the Federal Employee Attitude Survey, 1979, a survey was distributed to a stratified random sample of 20,000 employees to identify and analyze the factors influencing federal employee worker satisfaction. Questions on the survey ranged from demographics to personal evaluations of the work environment as recorded on a…

  12. Factors Influencing Stress, Burnout, and Retention of Secondary Teachers

    ERIC Educational Resources Information Center

    Fisher, Molly H.

    2011-01-01

    This study examines the stress, burnout, satisfaction, and preventive coping skills of nearly 400 secondary teachers to determine variables contributing to these major factors influencing teachers. Analysis of Variance (ANOVA) statistics were conducted that found the burnout levels between new and experienced teachers are significantly different,…

  13. Factors Influencing Career Choice of Management Students in India

    ERIC Educational Resources Information Center

    Agarwala, Tanuja

    2008-01-01

    Purpose: This paper aims to explore the influence of a range of factors on the career choice of management students in India. The importance of different individuals in the family and at work in making career choices among these students is also to be explored. In addition, the study seeks to address the relationship of the cultural values of…

  14. Factors that Influence Elementary Teachers Use of Computers

    ERIC Educational Resources Information Center

    Franklin, Cheryl

    2007-01-01

    The purpose of this quantitative study was to examine the ways elementary teachers use computer technology for instructional purposes and the factors that influence their use of computers. The population consisted of recent graduates from the elementary teacher preparation program at a mid-Atlantic university. Data were gathered using a survey…

  15. Social and Environmental Factors Influencing In-Prison Drug Use

    ERIC Educational Resources Information Center

    Woodall, James

    2012-01-01

    Purpose: There is a strong political imperative to regard the prison as a key social setting for health promotion, but evidence indicates that drug misuse continues to be a significant issue for many prisoners. This paper aims to examine the social and environmental factors within the setting that influence individuals' drug taking.…

  16. Factors Influencing Practical Training Quality in Iranian Agricultural Higher Education

    ERIC Educational Resources Information Center

    Mojarradi, Gholamreza; Karamidehkordi, Esmail

    2016-01-01

    This paper presents an analysis of the factors influencing the practical training quality of agricultural higher education programmes from the senior students' perspective. The study was conducted in two public universities located in the north-west of Iran using a cross-sectional survey and structured interviews with a randomised sample of 254…

  17. Consumers with Major Depressive Disorder: Factors Influencing Job Placement

    ERIC Educational Resources Information Center

    Hergenrather, Kenneth C.; Haase, Eileen; Zeglin, Robert J.; Rhodes, Scott D.

    2013-01-01

    The theory of planned behavior (TPB) was applied to study the factors that influence the intention of public rehabilitation placement professionals to place consumers with major depressive disorder (MDD) in jobs. A sample of 108 public rehabilitation placement professionals in the Mid-Atlantic region of the United States completed the MDD…

  18. Against Conventional Wisdom: Factors Influencing Hispanic Students' Reading Achievement

    ERIC Educational Resources Information Center

    Percell, Jay C.; Kaufman, Kristina

    2013-01-01

    The researchers performed a variable analysis of the 2002 Educational Longitudinal Study data investigating factors that influence students' reading scores on standardized tests. Hispanic and non-Hispanic Scores were analyzed and controlling variables were compared to determine the effect of each on both populations. Certain variables commonly…

  19. Factors Influencing Latino Participation in Community-Based Diabetes Education

    ERIC Educational Resources Information Center

    Francis, Sarah L.; Noterman, Amber; Litchfield, Ruth

    2014-01-01

    An Extension diabetes program (DP) was revised for Latinos; however, participation was limited. Factors influencing low participation rates were examined. Five Latinos interested in the DP participated in a focus group discussion. Transcripts were analyzed for themes. Preferred education programs were multi-session, local, group classes led by an…

  20. Factors Influencing Adjustment to Late-Life Divorce.

    ERIC Educational Resources Information Center

    Wilson, Keren Brown; DeShane, Michael R.

    Although the rate of divorce among older Americans has increased steadily, little attention has been paid to late life divorce. To describe the role of age and other factors which might influence adjustment to divorce in later life, data from a larger pilot study were used: 81 divorced persons over the age of 60 completed in-depth, structured…

  1. Factors Influencing BI Data Collection Strategies: An Empirical Investigation

    ERIC Educational Resources Information Center

    Ramakrishnan, Thiagarajan

    2010-01-01

    The purpose of this dissertation is to examine the external factors that influence an organizations' business intelligence (BI) data collection strategy when mediated by BI attributes. In this dissertation, data warehousing strategies are used as the basis on which to frame the exploration of BI data collection strategies. The attributes include…

  2. Factors that Influence Information Systems Undergraduates to Pursue IT Certification

    ERIC Educational Resources Information Center

    Hunsinger, D. Scott; Smith, Michael A.

    2008-01-01

    We identify factors that influence the intent of undergraduate information systems majors to pursue IT certification. Previous research has revealed that IT/IS hiring managers may use certification as a job requirement or to differentiate between job candidates with similar levels of education and experience. As well, salary surveys have shown…

  3. Factors Influencing School Choice in a School District in Delaware

    ERIC Educational Resources Information Center

    Kennedy, John J., Jr.

    2012-01-01

    The purpose of this descriptive study is to examine the factors that influenced parents in a school district in Delaware when they selected a high school for their child. This study also sought to examine the sources of information that parents used. Also examined was the impact of socio-economic status in the high school selection process. A…

  4. Factors Influencing Role Behaviors by Professional Exemplars in Hospitals

    ERIC Educational Resources Information Center

    Bolding, Deborah J.

    2013-01-01

    This basic qualitative study explored factors that influenced the development of professional role behaviors of nurses, occupational and physical therapists who were characterized as exemplars in the acute hospital setting. The participants, four occupational therapists, four nurses, and four physical therapists were interviewed using a…

  5. Social Factors Influencing Participation in Sport for the Deaf.

    ERIC Educational Resources Information Center

    Stewart, David A.

    1987-01-01

    The article looks at social factors influencing participation in sport by the deaf including communication mode and value orientations of community, family, school, and peers of both the hearing and deaf world. A model for integration of the deaf into sports is offered. (DB)

  6. Multilevel Factors Influencing Maternal Stress during the First Three Years.

    ERIC Educational Resources Information Center

    Mulsow, Miriam; Caldera, Yvonne M.; Pursley, Marta; Reifman, Alan; Huston, Aletha C.

    2002-01-01

    Study applies family stress theory to the influence of personal, child, and familial factors on a mother's parenting stress during the first 3 years of her infant's life. Mother's personality was most predictive of parenting stress. Counterintuitively, mothers who were more satisfied with work or school choices were more likely to be chronically…

  7. Factors That Influence Faculty Adoption of Learning-Centered Approaches

    ERIC Educational Resources Information Center

    Blumberg, Phyllis

    2016-01-01

    This article proposes a recommended course of action for faculty development based upon Rogers' theory of Diffusion of Innovations and data collected in a study looking at the prevalence of use of learning-centered teaching practices. Specific faculty development strategies are aligned with Rogers' factors influencing decisions to adopt…

  8. Abuse of Working Children and Influencing Factors, Turkey

    ERIC Educational Resources Information Center

    Oncu, Emine; Kurt, Ahmet Oner; Esenay, Figen Isik; Ozer, Fatma

    2013-01-01

    Objective: The study was planned as the research of the kind/kinds of abuse and the factors influencing the abuse that the children under 18 who are working full-time at a workplace and enrolled in a vocational training center subjected to. Method: Questionnaires were administered to 595 apprentices who were attending a vocational training center.…

  9. Factors Influencing Secondary School Teachers' Adoption of Teaching Blogs

    ERIC Educational Resources Information Center

    Lai, Hui-Min; Chen, Chin-Pin

    2011-01-01

    Recently, there has been a significant proliferation in the number of teaching blogs; however, little has been explored about what motivates teachers to adopt teaching blogs. The purpose of this study is to find out which factors can significantly influence teacher decisions regarding their teaching blog adoption and the relative importance of…

  10. Factors Influencing the Dielectric Properties of Agricultural and Food Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dielectric properties of materials are defined, and the major factors that influence these properties of agricultural and food materials, namely, frequency of the applied radio-frequency or microwave electric fields, and water content, temperature, and density of the materials, are discussed on the ...

  11. What Factors Influence Vietnamese Students' Choice of University?

    ERIC Educational Resources Information Center

    Dao, Mai Thi Ngoc; Thorpe, Anthony

    2015-01-01

    Purpose: The purpose of this paper is to report the factors that influence Vietnamese students' choice of university in a little researched context where the effects of globalization and education reform are changing higher education. Design/methodology/approach: A quantitative survey was completed by 1,124 current or recently completed university…

  12. Factors Influencing Residents' Satisfaction in Residential Aged Care

    ERIC Educational Resources Information Center

    Chou, Shu-Chiung; Boldy, Duncan P.; Lee, Andy H.

    2003-01-01

    Purpose: The aim of this study was to identify the important factors influencing residents' satisfaction in residential aged care and to provide a better understanding of their interrelationships. Design and Methods: A cross-sectional survey design was used to collect the required information, including resident satisfaction, resident dependency…

  13. Factors Influencing Knowledge Creation and Innovation in an Organisation

    ERIC Educational Resources Information Center

    Merx-Chermin, Mireille; Nijhof, Wim, J.

    2005-01-01

    Purpose: The purpose of this study is to gain a better understanding of the factors that influence the innovative power of organisations. The concept of innovation and innovative power was examined by analysing the relationship between the construct of the learning organisation, knowledge organisation and innovative organisation, and has resulted…

  14. The Influence Factors and Mechanism of Societal Risk Perception

    NASA Astrophysics Data System (ADS)

    Zheng, Rui; Shi, Kan; Li, Shu

    Risk perception is one of important subjects in management psychology and cognitive psychology. It is of great value in the theory and practice to investigate the societal hazards that the public cares a lot especially in Socio-economic transition period. A survey including 30 hazards and 6 risk attributes was designed and distributed to about 2, 485 residents of 8 districts, Beijing. The major findings are listed as following: Firstly, a scale of societal risk perception was designed and 2 factors were identified (Dread Risk & Unknown Risk). Secondly, structural equation model was used to analyze the influence factors and mechanism of societal risk perception. Risk preference, government support and social justice could influence societal risk perception directly. Government support fully moderated the relationship between government trust and societal risk perception. Societal risk perception influenced life satisfaction, public policy preferences and social development belief.

  15. Factors Influencing Renewable Energy Production & Supply - A Global Analysis

    NASA Astrophysics Data System (ADS)

    Ali, Anika; Saqlawi, Juman Al

    2016-04-01

    Renewable energy is one of the key technologies through which the energy needs of the future can be met in a sustainable and carbon-neutral manner. Increasing the share of renewable energy in the total energy mix of each country is therefore a critical need. While different countries have approached this in different ways, there are some common aspects which influence the pace and effectiveness of renewable energy incorporation. This presentation looks at data and information from 34 selected countries, analyses the patterns, compares the different parameters and identifies the common factors which positively influence renewable energy incorporation. The most successful countries are analysed for their renewable energy performance against their GDP, policy/regulatory initiatives in the field of renewables, landmass, climatic conditions and population to identify the most influencing factors to bring about positive change in renewable energy share.

  16. Factors influencing the flavour of game meat: A review.

    PubMed

    Neethling, J; Hoffman, L C; Muller, M

    2016-03-01

    Flavour is a very important attribute contributing to the sensory quality of meat and meat products. Although the sensory quality of meat includes orthonasal and retronasal aroma, taste, as well as appearance, juiciness and other textural attributes, the focus of this review is primarily on flavour. The influence of species, age, gender, muscle anatomical location, diet, harvesting conditions, ageing of meat, packaging and storage, as well as cooking method on the flavour of game meat are discussed. Very little research is available on the factors influencing the flavour of the meat derived from wild and free-living game species. The aim of this literature review is thus to discuss the key ante- and post-mortem factors that influence the flavour of game meat, with specific focus on wild and free-living South African game species.

  17. Inferring regulatory element landscapes and transcription factor networks from cancer methylomes.

    PubMed

    Yao, Lijing; Shen, Hui; Laird, Peter W; Farnham, Peggy J; Berman, Benjamin P

    2015-05-21

    Recent studies indicate that DNA methylation can be used to identify transcriptional enhancers, but no systematic approach has been developed for genome-wide identification and analysis of enhancers based on DNA methylation. We describe ELMER (Enhancer Linking by Methylation/Expression Relationships), an R-based tool that uses DNA methylation to identify enhancers and correlates enhancer state with expression of nearby genes to identify transcriptional targets. Transcription factor motif analysis of enhancers is coupled with expression analysis of transcription factors to infer upstream regulators. Using ELMER, we investigated more than 2,000 tumor samples from The Cancer Genome Atlas. We identified networks regulated by known cancer drivers such as GATA3 and FOXA1 (breast cancer), SOX17 and FOXA2 (endometrial cancer), and NFE2L2, SOX2, and TP63 (squamous cell lung cancer). We also identified novel networks with prognostic associations, including RUNX1 in kidney cancer. We propose ELMER as a powerful new paradigm for understanding the cis-regulatory interface between cancer-associated transcription factors and their functional target genes.

  18. Transcription factor binding at enhancers: shaping a genomic regulatory landscape in flux

    PubMed Central

    Palstra, Robert-Jan; Grosveld, Frank

    2012-01-01

    The mammalian genome is packed tightly in the nucleus of the cell. This packing is primarily facilitated by histone proteins and results in an ordered organization of the genome in chromosome territories that can be roughly divided in heterochromatic and euchromatic domains. On top of this organization several distinct gene regulatory elements on the same chromosome or other chromosomes are thought to dynamically communicate via chromatin looping. Advances in genome-wide technologies have revealed the existence of a plethora of these regulatory elements in various eukaryotic genomes. These regulatory elements are defined by particular in vitro assays as promoters, enhancers, insulators, and boundary elements. However, recent studies indicate that the in vivo distinction between these elements is often less strict. Regulatory elements are bound by a mixture of common and lineage-specific transcription factors which mediate the long-range interactions between these elements. Inappropriate modulation of the binding of these transcription factors can alter the interactions between regulatory elements, which in turn leads to aberrant gene expression with disease as an ultimate consequence. Here we discuss the bi-modal behavior of regulatory elements that act in cis (with a focus on enhancers), how their activity is modulated by transcription factor binding and the effect this has on gene regulation. PMID:23060900

  19. Factors influencing first childbearing timing decisions among men: Path analysis

    PubMed Central

    Kariman, Nourossadat; Amerian, Maliheh; Jannati, Padideh; Salmani, Fatemeh

    2016-01-01

    Background: Factors that influence men’s childbearing intentions have been relatively unexplored in the literature. Objective: This study aimed to determine the influencing factors about the first childbearing timing decisions of men. Materials and Methods: In this cross-sectional study, 300 men who were referred to private and governmental healthcare centers in Shahrood, Iran were randomly recruited from April to September 2014. Data were collected using a demographic questionnaire, the Quality of Life Questionnaire; ENRICH Marital Satisfaction Questionnaire, Synder’s Hope Scale, and the Multidimensional Scale of Perceived Social Support. Results: After removing the statistically insignificant paths, men’s age at marriage had the highest direct effect (β=0.86) on their first childbearing decision. Marital satisfaction (β=-0.09), social support (β=0.06), economic status (β=0.06), and quality of life (β=-0.08) were other effective factors on men’s first childbearing decisions. Moreover, marital satisfaction and social support had significant indirect effects on men’s childbearing decisions (β=-0.04 and -0.01, respectively). Conclusion: Many factors, including personal factors (age at marriage and quality of life), family factors (marital satisfaction), and social factors (social support), can affect men’s decision to have a child. Policymakers are hence required to develop strategies to promote the socioeconomic and family conditions of the couples and to encourage them to have as many children as they desire at an appropriate time. PMID:27738661

  20. A Review of Factors Influencing Athletes' Food Choices.

    PubMed

    Birkenhead, Karen L; Slater, Gary

    2015-11-01

    Athletes make food choices on a daily basis that can affect both health and performance. A well planned nutrition strategy that includes the careful timing and selection of appropriate foods and fluids helps to maximize training adaptations and, thus, should be an integral part of the athlete's training programme. Factors that motivate food selection include taste, convenience, nutrition knowledge and beliefs. Food choice is also influenced by physiological, social, psychological and economic factors and varies both within and between individuals and populations. This review highlights the multidimensional nature of food choice and the depth of previous research investigating eating behaviours. Despite numerous studies with general populations, little exploration has been carried out with athletes, yet the energy demands of sport typically require individuals to make more frequent and/or appropriate food choices. While factors that are important to general populations also apply to athletes, it seems likely, given the competitive demands of sport, that performance would be an important factor influencing food choice. It is unclear if athletes place the same degree of importance on these factors or how food choice is influenced by involvement in sport. There is a clear need for further research exploring the food choice motives of athletes, preferably in conjunction with research investigating dietary intake to establish if intent translates into practice. PMID:26243016

  1. A Review of Factors Influencing Athletes' Food Choices.

    PubMed

    Birkenhead, Karen L; Slater, Gary

    2015-11-01

    Athletes make food choices on a daily basis that can affect both health and performance. A well planned nutrition strategy that includes the careful timing and selection of appropriate foods and fluids helps to maximize training adaptations and, thus, should be an integral part of the athlete's training programme. Factors that motivate food selection include taste, convenience, nutrition knowledge and beliefs. Food choice is also influenced by physiological, social, psychological and economic factors and varies both within and between individuals and populations. This review highlights the multidimensional nature of food choice and the depth of previous research investigating eating behaviours. Despite numerous studies with general populations, little exploration has been carried out with athletes, yet the energy demands of sport typically require individuals to make more frequent and/or appropriate food choices. While factors that are important to general populations also apply to athletes, it seems likely, given the competitive demands of sport, that performance would be an important factor influencing food choice. It is unclear if athletes place the same degree of importance on these factors or how food choice is influenced by involvement in sport. There is a clear need for further research exploring the food choice motives of athletes, preferably in conjunction with research investigating dietary intake to establish if intent translates into practice.

  2. Factors influencing adherence to an emergency department national protocol.

    PubMed

    Ebben, Remco H A; Vloet, Lilian C M; de Groot, Joke Mintjes; van Achterberg, Theo

    2012-02-01

    The objective of this study was to identify factors that influence emergency nurses' adherence to an emergency department national protocol (EDNP). A survey of emergency nurses (n=200) and physicians with medical end responsibility on an emergency department (n=103) was carried out. Emergency nurses' self-reported adherence to the EDNP was 38%, 55% of the nurses and 44% of the physicians were aware of the protocol. Interference with professional autonomy, insufficient organizational support and the EDNP's applicability were indicated as barriers for adherence. The main influencing factor seems awareness. Other factors related to the individual, the organization and to protocol characteristics. Solely disseminating the EDNP is not enough to get the protocol used in clinical practice. PMID:21552130

  3. Cross-species cloning: influence of cytoplasmic factors on development.

    PubMed

    Sun, Yong-Hua; Zhu, Zuo-Yan

    2014-06-01

    It is widely accepted that the crosstalk between naive nucleus and maternal factors deposited in the egg cytoplasm before zygotic genome activation is crucial for early development. This crosstalk may also exert some influence on later development. It is interesting to clarify the relative roles of the zygotic genome and the cytoplasmic factors in development. Cross-species nuclear transfer (NT) between two distantly related species provides a unique system to study the relative role and crosstalk between egg cytoplasm and zygotic nucleus in development. In this review, we will summarize the recent progress of cross-species NT, with emphasis on the cross-species NT in fish and the influence of cytoplasmic factors on development. Finally, we conclude that the developmental process and its evolution should be interpreted in a systemic way, rather than in a way that solely focuses on the role of the nuclear genome.

  4. Variance of indoor radon concentration: Major influencing factors.

    PubMed

    Yarmoshenko, I; Vasilyev, A; Malinovsky, G; Bossew, P; Žunić, Z S; Onischenko, A; Zhukovsky, M

    2016-01-15

    Variance of radon concentration in dwelling atmosphere is analysed with regard to geogenic and anthropogenic influencing factors. Analysis includes review of 81 national and regional indoor radon surveys with varying sampling pattern, sample size and duration of measurements and detailed consideration of two regional surveys (Sverdlovsk oblast, Russia and Niška Banja, Serbia). The analysis of the geometric standard deviation revealed that main factors influencing the dispersion of indoor radon concentration over the territory are as follows: area of territory, sample size, characteristics of measurements technique, the radon geogenic potential, building construction characteristics and living habits. As shown for Sverdlovsk oblast and Niška Banja town the dispersion as quantified by GSD is reduced by restricting to certain levels of control factors. Application of the developed approach to characterization of the world population radon exposure is discussed. PMID:26409145

  5. Consumer's Online Shopping Influence Factors and Decision-Making Model

    NASA Astrophysics Data System (ADS)

    Yan, Xiangbin; Dai, Shiliang

    Previous research on online consumer behavior has mostly been confined to the perceived risk which is used to explain those barriers for purchasing online. However, perceived benefit is another important factor which influences consumers’ decision when shopping online. As a result, an integrated consumer online shopping decision-making model is developed which contains three elements—Consumer, Product, and Web Site. This model proposed relative factors which influence the consumers’ intention during the online shopping progress, and divided them into two different dimensions—mentally level and material level. We tested those factors with surveys, from both online volunteers and offline paper surveys with more than 200 samples. With the help of SEM, the experimental results show that the proposed model and method can be used to analyze consumer’s online shopping decision-making process effectively.

  6. Variance of indoor radon concentration: Major influencing factors.

    PubMed

    Yarmoshenko, I; Vasilyev, A; Malinovsky, G; Bossew, P; Žunić, Z S; Onischenko, A; Zhukovsky, M

    2016-01-15

    Variance of radon concentration in dwelling atmosphere is analysed with regard to geogenic and anthropogenic influencing factors. Analysis includes review of 81 national and regional indoor radon surveys with varying sampling pattern, sample size and duration of measurements and detailed consideration of two regional surveys (Sverdlovsk oblast, Russia and Niška Banja, Serbia). The analysis of the geometric standard deviation revealed that main factors influencing the dispersion of indoor radon concentration over the territory are as follows: area of territory, sample size, characteristics of measurements technique, the radon geogenic potential, building construction characteristics and living habits. As shown for Sverdlovsk oblast and Niška Banja town the dispersion as quantified by GSD is reduced by restricting to certain levels of control factors. Application of the developed approach to characterization of the world population radon exposure is discussed.

  7. Social factors and private benefits influence landholders' riverine restoration priorities in tropical Australia.

    PubMed

    Januchowski-Hartley, Stephanie Renee; Moon, Katie; Stoeckl, Natalie; Gray, Sally

    2012-11-15

    Private land conservation is an essential component of conservation that requires organizing both protection and restoration actions accordingly. Yet private land conservation programs are often formulated to generate public benefits, with inadequate consideration of costs or benefits to private landholders. Landholders' willingness to participate in conservation programs depends on a complex set of social factors, and the benefits they expect from participation. However, these two attributes are commonly evaluated independent of one another. We addressed this limitation through interviews aimed at determining landholders': 1) willingness to participate in restoration programs; 2) barriers to participation; 3) prioritization of proposed riverine restoration actions; 4) expected public or private benefits for undertaking proposed riverine restoration actions; and 5) most preferred incentive for undertaking proposed restoration actions on their land. Our results revealed four main findings. First, landholders stated that biases towards ecological rather than production outcomes, impractical programs, and government mistrust (structural factors) were the major barriers that prevented them from participating in riverine restoration on their land. Second, private benefits influenced landholders' willingness to engage riverine restoration. Third, 'a sense of stewardship and improved landscape aesthetics' (an internal factor) was the most commonly reported private benefit. Fourth, the most preferred incentives for high priority restoration actions were cash for on-ground works, extension and community recognition. We highlight the importance of designing private land conservation programs that align with landholders' priorities and deliver public benefits.

  8. Social factors and private benefits influence landholders' riverine restoration priorities in tropical Australia.

    PubMed

    Januchowski-Hartley, Stephanie Renee; Moon, Katie; Stoeckl, Natalie; Gray, Sally

    2012-11-15

    Private land conservation is an essential component of conservation that requires organizing both protection and restoration actions accordingly. Yet private land conservation programs are often formulated to generate public benefits, with inadequate consideration of costs or benefits to private landholders. Landholders' willingness to participate in conservation programs depends on a complex set of social factors, and the benefits they expect from participation. However, these two attributes are commonly evaluated independent of one another. We addressed this limitation through interviews aimed at determining landholders': 1) willingness to participate in restoration programs; 2) barriers to participation; 3) prioritization of proposed riverine restoration actions; 4) expected public or private benefits for undertaking proposed riverine restoration actions; and 5) most preferred incentive for undertaking proposed restoration actions on their land. Our results revealed four main findings. First, landholders stated that biases towards ecological rather than production outcomes, impractical programs, and government mistrust (structural factors) were the major barriers that prevented them from participating in riverine restoration on their land. Second, private benefits influenced landholders' willingness to engage riverine restoration. Third, 'a sense of stewardship and improved landscape aesthetics' (an internal factor) was the most commonly reported private benefit. Fourth, the most preferred incentives for high priority restoration actions were cash for on-ground works, extension and community recognition. We highlight the importance of designing private land conservation programs that align with landholders' priorities and deliver public benefits. PMID:22705856

  9. Mutational Landscape and Antiproliferative Functions of ELF Transcription Factors in Human Cancer.

    PubMed

    Ando, Mizuo; Kawazu, Masahito; Ueno, Toshihide; Koinuma, Daizo; Ando, Koji; Koya, Junji; Kataoka, Keisuke; Yasuda, Takahiko; Yamaguchi, Hiroyuki; Fukumura, Kazutaka; Yamato, Azusa; Soda, Manabu; Sai, Eirin; Yamashita, Yoshihiro; Asakage, Takahiro; Miyazaki, Yasushi; Kurokawa, Mineo; Miyazono, Kohei; Nimer, Stephen D; Yamasoba, Tatsuya; Mano, Hiroyuki

    2016-04-01

    ELF4 (also known as MEF) is a member of the ETS family of transcription factors. An oncogenic role for ELF4 has been demonstrated in hematopoietic malignancies, but its function in epithelial tumors remains unclear. Here, we show that ELF4 can function as a tumor suppressor and is somatically inactivated in a wide range of human tumors. We identified a missense mutation affecting the transactivation potential of ELF4 in oral squamous cell carcinoma cells. Restoration of the transactivation activity through introduction of wild-type ELF4 significantly inhibited cell proliferation in vitro and tumor xenograft growth. Furthermore, we found that ELF1 and ELF2, closely related transcription factors to ELF4, also exerted antiproliferative effects in multiple cancer cell lines. Mutations in ELF1 and ELF2, as in ELF4, were widespread across human cancers, but were almost all mutually exclusive. Moreover, chromatin immunoprecipitation coupled with high-throughput sequencing revealed ELF4-binding sites in genomic regions adjacent to genes related to cell-cycle regulation and apoptosis. Finally, we provide mechanistic evidence that the antiproliferative effects of ELF4 were mediated through the induction of HRK, an activator of apoptosis, and DLX3, an inhibitor of cell growth. Collectively, our findings reveal a novel subtype of human cancer characterized by inactivating mutations in the ELF subfamily of proteins, and warrant further investigation of the specific settings where ELF restoration may be therapeutically beneficial. Cancer Res; 76(7); 1814-24. ©2016 AACR. PMID:26921333

  10. From Lab to Field: The Influence of Urban Landscapes on the Invasive Potential of Wolbachia in Brazilian Aedes aegypti Mosquitoes

    PubMed Central

    Caragata, Eric Pearce; Silva, Jéssica Barreto Lopes; Villela, Daniel Antunes Maciel; Maciel-de-Freitas, Rafael; Moreira, Luciano Andrade

    2015-01-01

    Background The symbiotic bacterium Wolbachia is currently being trialled as a biocontrol agent in several countries to reduce dengue transmission. Wolbachia can invade and spread to infect all individuals within wild mosquito populations, but requires a high rate of maternal transmission, strong cytoplasmic incompatibility and low fitness costs in the host in order to do so. Additionally, extensive differences in climate, field-release protocols, urbanization level and human density amongst the sites where this bacterium has been deployed have limited comparison and analysis of Wolbachia’s invasive potential. Methodology/Principal Findings We examined key phenotypic effects of the wMel Wolbachia strain in laboratory Aedes aegypti mosquitoes with a Brazilian genetic background to characterize its invasive potential. We show that the wMel strain causes strong cytoplasmic incompatibility, a high rate of maternal transmission and has no evident detrimental effect on host fecundity or fertility. Next, to understand the effects of different urban landscapes on the likelihood of mosquito survival, we performed mark-release-recapture experiments using Wolbachia-uninfected Brazilian mosquitoes in two areas of Rio de Janeiro where Wolbachia will be deployed in the future. We characterized the mosquito populations in relation to the socio-demographic conditions at these sites, and at three other future release areas. We then constructed mathematical models using both the laboratory and field data, and used these to describe the influence of urban environmental conditions on the likelihood that the Wolbachia infection frequency could reach 100% following mosquito release. We predict successful invasion at all five field sites, however the conditions by which this occurs vary greatly between sites, and are strongly influenced by the size of the local mosquito population. Conclusions/Significance Through analysis of laboratory, field and mathematical data, we show that the w

  11. FACTORS INFLUENCING THE DESIGN OF BIOACCUMULATION FACTOR AND BIOTA-SEDIMENT ACCUMULATION FACTOR FIELD STUDIES

    EPA Science Inventory

    A series of modeling simulations were performed to develop an understanding of the underlying factors and principles involved in developing field sampling designs for measuring bioaccumulation factors (BAFs) and biota-sediment accumulation factors (BSAFs. These simulations reveal...

  12. FACTORS INFLUENCING THE DESIGN OF BIOACCUMULATION FACTOR AND BIOTA-SEDIMENT ACCUMULATION FACTOR FIELD STUDIES

    EPA Science Inventory

    General guidance for designing field studies to measure bioaccumulation factors (BAFs) and biota-sediment accumulation factors (BSAFs) is not available. To develop such guidance, a series of modeling simulations were performed to evaluate the underlying factors and principles th...

  13. Mealybug species from Chilean agricultural landscapes and main factors influencing the genetic structure of Pseudococcus viburni.

    PubMed

    Correa, Margarita C G; Lombaert, Eric; Malausa, Thibaut; Crochard, Didier; Alvear, Andrés; Zaviezo, Tania; Palero, Ferran

    2015-01-01

    The present study aimed to characterize the distribution of mealybug species along Chilean agro-ecosystems and to determine the relative impact of host plant, management strategy, geography and micro-environment on shaping the distribution and genetic structure of the obscure mealybug Pseudococcus viburni. An extensive survey was completed using DNA barcoding methods to identify Chilean mealybugs to the species level. Moreover, a fine-scale study of Ps. viburni genetic diversity and population structure was carried out, genotyping 529 Ps. viburni individuals with 21 microsatellite markers. Samples from 16 localities were analyzed using Bayesian and spatially-explicit methods and the genetic dataset was confronted to host-plant, management and environmental data. Chilean crops were found to be infested by Ps. viburni, Pseudococcus meridionalis, Pseudococcus longispinus and Planococcus citri, with Ps. viburni and Ps. meridionalis showing contrasting distribution and host-plant preference patterns. Ps. viburni samples presented low genetic diversity levels but high genetic differentiation. While no significant genetic variance could be assigned to host-plant or management strategy, climate and geography were found to correlate significantly with genetic differentiation levels. The genetic characterization of Ps. viburni within Chile will contribute to future studies tracing back the origin and improving the management of this worldwide invader. PMID:26559636

  14. Landscape and seasonal factors influence salmonella and campylobacter prevalence in a rural mixed use watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella and Campylobacter prevalence in stream networks of the Satilla River Basin (SRB) were monitored monthly from August 2007 to August 2009 to study relationships between these pathogens and land use, presence of poultry houses and wastewater treatment plant (WWTP) discharge. Salmonella and ...

  15. Mealybug species from Chilean agricultural landscapes and main factors influencing the genetic structure of Pseudococcus viburni.

    PubMed

    Correa, Margarita C G; Lombaert, Eric; Malausa, Thibaut; Crochard, Didier; Alvear, Andrés; Zaviezo, Tania; Palero, Ferran

    2015-11-12

    The present study aimed to characterize the distribution of mealybug species along Chilean agro-ecosystems and to determine the relative impact of host plant, management strategy, geography and micro-environment on shaping the distribution and genetic structure of the obscure mealybug Pseudococcus viburni. An extensive survey was completed using DNA barcoding methods to identify Chilean mealybugs to the species level. Moreover, a fine-scale study of Ps. viburni genetic diversity and population structure was carried out, genotyping 529 Ps. viburni individuals with 21 microsatellite markers. Samples from 16 localities were analyzed using Bayesian and spatially-explicit methods and the genetic dataset was confronted to host-plant, management and environmental data. Chilean crops were found to be infested by Ps. viburni, Pseudococcus meridionalis, Pseudococcus longispinus and Planococcus citri, with Ps. viburni and Ps. meridionalis showing contrasting distribution and host-plant preference patterns. Ps. viburni samples presented low genetic diversity levels but high genetic differentiation. While no significant genetic variance could be assigned to host-plant or management strategy, climate and geography were found to correlate significantly with genetic differentiation levels. The genetic characterization of Ps. viburni within Chile will contribute to future studies tracing back the origin and improving the management of this worldwide invader.

  16. Mealybug species from Chilean agricultural landscapes and main factors influencing the genetic structure of Pseudococcus viburni

    PubMed Central

    Correa, Margarita C. G.; Lombaert, Eric; Malausa, Thibaut; Crochard, Didier; Alvear, Andrés; Zaviezo, Tania; Palero, Ferran

    2015-01-01

    The present study aimed to characterize the distribution of mealybug species along Chilean agro-ecosystems and to determine the relative impact of host plant, management strategy, geography and micro-environment on shaping the distribution and genetic structure of the obscure mealybug Pseudococcus viburni. An extensive survey was completed using DNA barcoding methods to identify Chilean mealybugs to the species level. Moreover, a fine-scale study of Ps. viburni genetic diversity and population structure was carried out, genotyping 529 Ps. viburni individuals with 21 microsatellite markers. Samples from 16 localities were analyzed using Bayesian and spatially-explicit methods and the genetic dataset was confronted to host-plant, management and environmental data. Chilean crops were found to be infested by Ps. viburni, Pseudococcus meridionalis, Pseudococcus longispinus and Planococcus citri, with Ps. viburni and Ps. meridionalis showing contrasting distribution and host-plant preference patterns. Ps. viburni samples presented low genetic diversity levels but high genetic differentiation. While no significant genetic variance could be assigned to host-plant or management strategy, climate and geography were found to correlate significantly with genetic differentiation levels. The genetic characterization of Ps. viburni within Chile will contribute to future studies tracing back the origin and improving the management of this worldwide invader. PMID:26559636

  17. INFLUENCE OF HUMAN ACTIVITIES ON LANDSCAPE AND HABITAT FACTORS CONTROLLING PACIFIC NORTHWEST COASTAL STREAM FISH ASSEMBLAGES

    EPA Science Inventory

    Fish assemblages in the Oregon-Washington coast range consist primarily of coldwater taxa of salmonids, cottids, dace, and Pacific giant salamander. This region has a dynamic natural disturbance regime, where mass failures, debris torrents, fire, and tree-fall are driven by clim...

  18. The functional landscape bound to the transcription factors of Escherichia coli K-12.

    PubMed

    Pérez-Rueda, Ernesto; Tenorio-Salgado, Silvia; Huerta-Saquero, Alejandro; Balderas-Martínez, Yalbi I; Moreno-Hagelsieb, Gabriel

    2015-10-01

    Motivated by the experimental evidences accumulated in the last ten years and based on information deposited in RegulonDB, literature look up, and sequence analysis, we analyze the repertoire of 304 DNA-binding Transcription factors (TFs) in Escherichia coli K-12. These regulators were grouped in 78 evolutionary families and are regulating almost half of the total genes in this bacterium. In structural terms, 60% of TFs are composed by two-domains, 30% are monodomain, and 10% three- and four-structural domains. As previously noticed, the most abundant DNA-binding domain corresponds to the winged helix-turn-helix, with few alternative DNA-binding structures, resembling the hypothesis of successful protein structures with the emergence of new ones at low scales. In summary, we identified and described the characteristics associated to the DNA-binding TF in E. coli K-12. We also identified twelve functional modules based on a co-regulated gene matrix. Finally, diverse regulons were predicted based on direct associations between the TFs and potential regulated genes. This analysis should increase our knowledge about the gene regulation in the bacterium E. coli K-12, and provide more additional clues for comprehensive modelling of transcriptional regulatory networks in other bacteria.

  19. Contemporary and historic factors influence differently genetic differentiation and diversity in a tropical palm

    PubMed Central

    da Silva Carvalho, C; Ribeiro, M C; Côrtes, M C; Galetti, M; Collevatti, R G

    2015-01-01

    Population genetics theory predicts loss in genetic variability because of drift and inbreeding in isolated plant populations; however, it has been argued that long-distance pollination and seed dispersal may be able to maintain gene flow, even in highly fragmented landscapes. We tested how historical effective population size, historical migration and contemporary landscape structure, such as forest cover, patch isolation and matrix resistance, affect genetic variability and differentiation of seedlings in a tropical palm (Euterpe edulis) in a human-modified rainforest. We sampled 16 sites within five landscapes in the Brazilian Atlantic forest and assessed genetic variability and differentiation using eight microsatellite loci. Using a model selection approach, none of the covariates explained the variation observed in inbreeding coefficients among populations. The variation in genetic diversity among sites was best explained by historical effective population size. Allelic richness was best explained by historical effective population size and matrix resistance, whereas genetic differentiation was explained by matrix resistance. Coalescence analysis revealed high historical migration between sites within landscapes and constant historical population sizes, showing that the genetic differentiation is most likely due to recent changes caused by habitat loss and fragmentation. Overall, recent landscape changes have a greater influence on among-population genetic variation than historical gene flow process. As immediate restoration actions in landscapes with low forest amount, the development of more permeable matrices to allow the movement of pollinators and seed dispersers may be an effective strategy to maintain microevolutionary processes. PMID:25873150

  20. The Impact of Landscape Complexity on Invertebrate Diversity in Edges and Fields in an Agricultural Area.

    PubMed

    Evans, Tracy R; Mahoney, Meredith J; Cashatt, Everett D; Noordijk, Jinze; de Snoo, Geert; Musters, C J M

    2016-01-01

    Invertebrate diversity is important for a multitude of ecosystem services and as a component of the larger ecological food web. A better understanding of the factors influencing invertebrate taxonomic richness and diversity at both local and landscape scales is important for conserving biodiversity within the agricultural landscape. The aim of this study was to determine if invertebrate richness and diversity in agricultural field interiors and edges in central Illinois, USA, were related to the complexity of the surrounding landscape. Our results show taxonomic richness and diversity in field edges is positively related to large scale landscape complexity, but the relationship is negative for field interiors. These unexpected results need further study.

  1. The Impact of Landscape Complexity on Invertebrate Diversity in Edges and Fields in an Agricultural Area

    PubMed Central

    Evans, Tracy R.; Mahoney, Meredith J.; Cashatt, Everett D.; Noordijk, Jinze; de Snoo, Geert; Musters, C. J. M.

    2016-01-01

    Invertebrate diversity is important for a multitude of ecosystem services and as a component of the larger ecological food web. A better understanding of the factors influencing invertebrate taxonomic richness and diversity at both local and landscape scales is important for conserving biodiversity within the agricultural landscape. The aim of this study was to determine if invertebrate richness and diversity in agricultural field interiors and edges in central Illinois, USA, were related to the complexity of the surrounding landscape. Our results show taxonomic richness and diversity in field edges is positively related to large scale landscape complexity, but the relationship is negative for field interiors. These unexpected results need further study. PMID:26848691

  2. The Influence of Contextual and Psychosocial Factors on Handwashing.

    PubMed

    Seimetz, Elisabeth; Boyayo, Anne-Marie; Mosler, Hans-Joachim

    2016-06-01

    Even though washing hands with soap is among the most effective measures to reduce the risk of infection, handwashing rates in infrastructure-restricted settings remain seriously low. Little is known about how context alone and in interaction with psychosocial factors influence hand hygiene behavior. The aim of this article was to explore how both contextual and psychosocial factors affect handwashing practices. A cross-sectional survey was conducted with 660 caregivers of primary school children in rural Burundi. Hierarchical regression analyses revealed that household wealth, the amount of water per person, and having a designated place for washing hands were contextual factors significantly predicting handwashing frequency, whereas the contextual factors, time spent collecting water and amount of money spent on soap, were not significant predictors. The contextual factors explained about 13% of the variance of reported handwashing frequency. The addition of the psychosocial factors to the regression model resulted in a significant 41% increase of explained variation in handwashing frequency. In this final model, the amount of water was the only contextual factor that remained a significant predictor. The most important predictors were a belief of self-efficacy, planning how, when, and where to wash hands, and always remembering to do so. The findings suggest that contextual constraints might be perceived rather than actual barriers and highlight the role of psychosocial factors in understanding hygiene behaviors. PMID:27139449

  3. Succesful Lean Manufacturing Implementation: Internal Key Influencing Factors

    NASA Astrophysics Data System (ADS)

    Virginia, Iuga; Claudiu, Kifor

    2015-09-01

    Manufacturing sectors and companies all over the world are successfully implementing lean principles within their processes. Nowadays, lean has become an indispensable part of global players. Companies worldwide need to be aware of multiple factors which weigh heavily on the success or failure of lean implementation. This paper focuses on giving a brief and structured overview over the fundamental organizational factors which play a substantial role for the lean manufacturing (LM) implementation process. The study below focuses on internal factors which are indispensable for a successful LM implementation within organizations. It is imperative that these internal factors are known, recognized and taken into consideration during the whole LM implementation process. Ignoring their influence on the process's implementation may lead to endangering the expected results or to making the process more difficult which could result in much higher human resource consumption.

  4. Arbuscular Mycorhizal Fungi Associated with the Olive Crop across the Andalusian Landscape: Factors Driving Community Differentiation

    PubMed Central

    Montes-Borrego, Miguel; Metsis, Madis; Landa, Blanca B.

    2014-01-01

    Background In the last years, many olive plantations in southern Spain have been mediated by the use of self-rooted planting stocks, which have incorporated commercial AMF during the nursery period to facilitate their establishment. However, this was practised without enough knowledge on the effect of cropping practices and environment on the biodiversity of AMF in olive orchards in Spain. Methodology/Principal Findings Two culture-independent molecular methods were used to study the AMF communities associated with olive in a wide-region analysis in southern Spain including 96 olive locations. The use of T-RFLP and pyrosequencing analysis of rDNA sequences provided the first evidence of an effect of agronomic and climatic characteristics, and soil physicochemical properties on AMF community composition associated with olive. Thus, the factors most strongly associated to AMF distribution varied according to the technique but included among the studied agronomic characteristics the cultivar genotype and age of plantation and the irrigation regimen but not the orchard management system or presence of a cover crop to prevent soil erosion. Soil physicochemical properties and climatic characteristics most strongly associated to the AMF community composition included pH, textural components and nutrient contents of soil, and average evapotranspiration, rainfall and minimum temperature of the sampled locations. Pyrosequencing analysis revealed 33 AMF OTUs belonging to five families, with Archaeospora spp., Diversispora spp. and Paraglomus spp., being first records in olive. Interestingly, two of the most frequent OTUs included a diverse group of Claroideoglomeraceae and Glomeraceae sequences, not assigned to any known AMF species commonly used as inoculants in olive during nursery propagation. Conclusions/Significance Our data suggests that AMF can exert higher host specificity in olive than previously thought, which may have important implications for redirecting the

  5. Population growth, demographic change, and cultural landscapes.

    PubMed

    Woodgate, G; Sage, C

    1994-01-01

    The inclusion of both ecological and socioeconomic components within landscapes makes possible the perception of the hierarchical character of landscape organization. A research approach is needed to conceptualize cultural landscapes as the product of interaction between society and nature. Richard Norgaard's 1984 paper on coevolutionary agricultural development attempts to meet this challenge. Coevolution is the interactive synthesis of natural and social mechanisms of change that characterize the relationship between social systems and ecosystems. The relationship between population, consumption, and environmental changes is complex. Currently industrialized countries present the biggest threat to global environmental resources. The issue of carrying capacity is the corollary of population and the environment. It is primarily the technological factor rather than population that needs to be controlled. The relationship between rich and poor countries is determined by superior economic power. An analysis of landscape change is made, tracing the coevolution of society and environment from the end of the feudal era and making comparisons with continental Europe. Over the years since 1945 the need to realize potential economies of scale has resulted in a wholesale loss of woodlands, hedgerows, and small ponds in the UK. In a global context the likely impacts of population growth and demographic change on landscapes will be influenced by such socioeconomic factors as technology and affluence; policies that ignore cause and effect; and the traditional tendency to treat the environment as a waste repository and a supply depot. PMID:12290867

  6. Characteristics of aquatic bacterial community and the influencing factors in an urban river.

    PubMed

    Wang, Peng; Chen, Bo; Yuan, Ruiqiang; Li, Chuangqiong; Li, Yan

    2016-11-01

    Bacteria play a critical role in environmental and ecological processes in river ecosystems. We studied the bacterial community in the Ganjiang River, a major tributary of the Yangtze River, as it flowed through Nanchang, the largest city in the Ganjiang River basin. Water was sampled at five sites monthly during the wet season, and the bacterial community was characterized using Illumina high-throughput sequencing. A total of 811 operational taxonomic units (OTUs) were observed for all samples, ranging from 321 to 519 for each sample. The bacterial communities were maintained by a core of OTUs that persisted longitudinally and monthly. Actinobacteria (41.17% of total sequences) and Proteobacteria (31.80%) were the dominant phyla, while Firmicutes (mostly genus Lactococcus) became most abundant during flooding. Temperature and flow rate, rather than water chemistry, were the main factors influencing the bacterial community in river water. Temperature was the best individual parameter explaining the variations in OTU abundance, while flow rate was the best individual parameter explaining the variations in phylum abundance. Except for Proteobacteria, the relative abundance of bacterial phyla did not differ significantly between sites, and the degrees of influence of urban landscape on the bacterial community were estimated to be 17%-34%.

  7. [Seasonal variation and related influencing factors for tuberculosis].

    PubMed

    Zhang, Z B; Lu, Z Q; Xie, H; Duan, Q H

    2016-08-10

    Tuberculosis is recognized as a chronic respiratory infectious disease and still one of the important public health issues in the world. Douglas reported an unique seasonal pattern (summer peak) of tuberculosis, when compared with most other respiratory diseases in 1996. Since then, there had been many other researchers notified various patterns of seasonality on TB. This paper reviewed all the studies published in the last five years and analyzed the current findings on seasonal variability and influencing factors, in order to explore the risk factors to provide evidence for prevention and control strategies on tuberculosis. PMID:27539356

  8. Children's disaster reactions: the influence of family and social factors.

    PubMed

    Pfefferbaum, Betty; Jacobs, Anne K; Houston, J Brian; Griffin, Natalie

    2015-07-01

    This review examines family (demographics, parent reactions and interactions, and parenting style) and social (remote effects, disaster media coverage, exposure to secondary adversities, and social support) factors that influence children's disaster reactions. Lower family socioeconomic status, high parental stress, poor parental coping, contact with media coverage, and exposure to secondary adversities have been associated with adverse outcomes. Social support may provide protection to children in the post-disaster environment though more research is needed to clarify the effects of certain forms of social support. The interaction of the factors described in this review with culture needs further exploration.

  9. The Influence of Various Factors on the Methane Fermentation Process

    NASA Astrophysics Data System (ADS)

    Kurbanova, M. G.; Egushova, E. A.; Pozdnjakova, OG

    2015-09-01

    The article describes the stages of the methane fermentation process. The phases of methane formation are characterized. The results of the experimental data based on the study of various factors influencing the rate of biogas production and its yield are presented. Such factors as the size of the substrate particles and temperature conditions in the reactor are considered. It is revealed on the basis of experimental data which of the farm animals and poultry excrements are exposed to the most complete fermentation without special preparation. The relationship between fermentation regime, particle size of the feedstock and biogas yield is graphically presented.

  10. Metal Oxide Gas Sensors: Sensitivity and Influencing Factors

    PubMed Central

    Wang, Chengxiang; Yin, Longwei; Zhang, Luyuan; Xiang, Dong; Gao, Rui

    2010-01-01

    Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above. PMID:22294916

  11. Factors influencing the dielectric properties of agricultural and food products.

    PubMed

    Nelson, Stuart O; Trabelsi, Samir

    2012-01-01

    Dielectric properties of materials are defined, and the major factors that influence these properties of agricultural and food materials, namely, frequency of the applied radiofrequency or microwave electric fields, and water content, temperature, and density of the materials, are discussed on the basis of fundamental concepts. The dependence of measured dielectric properties on these factors is illustrated graphically and discussed for a number of agricultural and food products, including examples of grain, peanuts, fruit, eggs, fresh chicken meat, whey protein gel, and a macaroni and cheese preparation. General observations are provided on the nature of the variation of the dielectric properties with the major variables.

  12. Children's disaster reactions: the influence of family and social factors.

    PubMed

    Pfefferbaum, Betty; Jacobs, Anne K; Houston, J Brian; Griffin, Natalie

    2015-07-01

    This review examines family (demographics, parent reactions and interactions, and parenting style) and social (remote effects, disaster media coverage, exposure to secondary adversities, and social support) factors that influence children's disaster reactions. Lower family socioeconomic status, high parental stress, poor parental coping, contact with media coverage, and exposure to secondary adversities have been associated with adverse outcomes. Social support may provide protection to children in the post-disaster environment though more research is needed to clarify the effects of certain forms of social support. The interaction of the factors described in this review with culture needs further exploration. PMID:25980512

  13. An Integrative Review of Factors Influencing Breastfeeding in Adolescent Mothers

    PubMed Central

    Kanhadilok, Supannee; McGrath, Jacqueline M.

    2015-01-01

    ABSTRACT The purpose of this integrative review was to describe factors that influence breastfeeding behaviors in adolescent mothers. Twenty-two articles met inclusion criteria. Findings showed that most adolescent mothers intended to breastfeed during pregnancy. Yet, breastfeeding initiation ranged from 39% to 69%. Almost half of adolescent mothers stopped within 1 month. Less than 25% continued to breastfeeding behaviors to 6 months. Factors that influenced breastfeeding decisions in adolescent mothers included social and cultural norms. Personal beliefs about being a good mother were important to intention and initiation of breastfeeding. Promoting maternal competence was found to be essential to breastfeeding initiation and continuation for adolescent mothers. Support from partners and professionals also led to positive attitudes toward breastfeeding initiation and continuation. PMID:26957895

  14. Landscape influences on dispersal behaviour: a theoretical model and empirical test using the fire salamander, Salamandra infraimmaculata.

    PubMed

    Kershenbaum, Arik; Blank, Lior; Sinai, Iftach; Merilä, Juha; Blaustein, Leon; Templeton, Alan R

    2014-06-01

    When populations reside within a heterogeneous landscape, isolation by distance may not be a good predictor of genetic divergence if dispersal behaviour and therefore gene flow depend on landscape features. Commonly used approaches linking landscape features to gene flow include the least cost path (LCP), random walk (RW), and isolation by resistance (IBR) models. However, none of these models is likely to be the most appropriate for all species and in all environments. We compared the performance of LCP, RW and IBR models of dispersal with the aid of simulations conducted on artificially generated landscapes. We also applied each model to empirical data on the landscape genetics of the endangered fire salamander, Salamandra infraimmaculata, in northern Israel, where conservation planning requires an understanding of the dispersal corridors. Our simulations demonstrate that wide dispersal corridors of the low-cost environment facilitate dispersal in the IBR model, but inhibit dispersal in the RW model. In our empirical study, IBR explained the genetic divergence better than the LCP and RW models (partial Mantel correlation 0.413 for IBR, compared to 0.212 for LCP, and 0.340 for RW). Overall dispersal cost in salamanders was also well predicted by landscape feature slope steepness (76%), and elevation (24%). We conclude that fire salamander dispersal is well characterised by IBR predictions. Together with our simulation findings, these results indicate that wide dispersal corridors facilitate, rather than hinder, salamander dispersal. Comparison of genetic data to dispersal model outputs can be a useful technique in inferring dispersal behaviour from population genetic data.

  15. Biodiversity in Organic Farmland - How Does Landscape Context Influence Species Diversity in Organic Vs. Conventional Agricultural Fields?

    NASA Astrophysics Data System (ADS)

    Seufert, V.; Wood, S.; Reid, A.; Gonzalez, A.; Rhemtulla, J.; Ramankutty, N.

    2014-12-01

    The most important current driver of biodiversity loss is the conversion of natural habitats for human land uses, mostly for the purpose of food production. However, by causing this biodiversity loss, food production is eroding the very same ecosystem services (e.g. pollination and soil fertility) that it depends on. We therefore need to adopt more wildlife-friendly agricultural practices that can contribute to preserving biodiversity. Organic farming has been shown to typically host higher biodiversity than conventional farming. But how is the biodiversity benefit of organic management dependent on the landscape context farms are situated in? To implement organic farming as an effective means for protecting biodiversity and enhancing ecosystem services we need to understand better under what conditions organic management is most beneficial for species. We conducted a meta-analysis of the literature to answer this question, compiling the most comprehensive database to date of studies that monitored biodiversity in organic vs. conventional fields. We also collected information about the landscape surrounding these fields from remote sensing products. Our database consists of 348 study sites across North America and Europe. Our analysis shows that organic management can improve biodiversity in agricultural fields substantially. It is especially effective at preserving biodiversity in homogeneous landscapes that are structurally simplified and dominated by either cropland or pasture. In heterogeneous landscapes conventional agriculture might instead already hold high biodiversity, and organic management does not appear to provide as much of a benefit for species richness as in simplified landscapes. Our results suggest that strategies to maintain biodiversity-dependent ecosystem services should include a combination of pristine natural habitats, wildlife-friendly farming systems like organic farming, and high-yielding conventional systems, interspersed in structurally

  16. [Influencing factors in measuring absorption coefficient of suspended particulate matters].

    PubMed

    Yu, Xiao-long; Shen, Fang; Zhang, Jin-fang

    2013-05-01

    Absorption coefficient of suspended particulate matters in natural water is one of the key parameters in ocean color remote sensing. In order to study the influencing factors that affect the measurement, a series of experiments were designed to measure samples using transmittance method (T method), transmittance-reflectance method (T-R method) and absorptance method (A method). The results shows that absorption coefficient measured by the A method has a much lower error compared to the T method and T-R method due to influencing factors,such as filter-to-filter variations, water content of the filter, and homogeneity of filter load and so on. Another factor influence absorption coefficient is path-length amplification induced by multiple scattering inside the filter. To determine the path-length amplification, the true absorption was measured by AC-s (WetLabs). The linear fitting result shows that the mean path-length amplification is much higher for the A method than that of the T-R method and the T method (4.01 versus 2.20 and 2.32), and the corresponding correlation coefficient are 0.90, 0.87 and 0.80. For the A method and the T-R method, higher correlation coefficients are calculated when using polynomial fitting, and the value are 0.95 and 0.94. Analysis of the mean relative error caused by different influencing factors indicates that path-length amplification is the largest error source in measuring the absorption coefficient.

  17. Planetary Landscape Geography

    NASA Astrophysics Data System (ADS)

    Hargitai, H.

    INTRODUCTION Landscape is one of the most often used category in physical ge- ography. The term "landshap" was introduced by Dutch painters in the 15-16th cen- tury. [1] The elements that build up a landscape (or environment) on Earth consists of natural (biogenic and abiogenic - lithologic, atmospheric, hydrologic) and artificial (antropogenic) factors. Landscape is a complex system of these different elements. The same lithology makes different landscapes under different climatic conditions. If the same conditions are present, the same landscape type will appear. Landscapes build up a hierarchic system and cover the whole surface. On Earth, landscapes can be classified and qualified according to their characteristics: relief forms (morphology), and its potential economic value. Aesthetic and subjective parameters can also be considered. Using the data from landers and data from orbiters we can now classify planetary landscapes (these can be used as geologic mapping units as well). By looking at a unknown landscape, we can determine the processes that created it and its development history. This was the case in the Pathfinder/Sojourner panoramas. [2]. DISCUSSION Planetary landscape evolution. We can draw a raw landscape develop- ment history by adding the different landscape building elements to each other. This has a strong connection with the planet's thermal evolution (age of the planet or the present surface materials) and with orbital parameters (distance from the central star, orbit excentricity etc). This way we can build a complex system in which we use differ- ent evolutional stages of lithologic, atmospheric, hydrologic and biogenic conditions which determine the given - Solar System or exoplanetary - landscape. Landscape elements. "Simple" landscapes can be found on asteroids: no linear horizon is present (not differentiated body, only impact structures), no atmosphere (therefore no atmospheric scattering - black sky as part of the landscape) and no

  18. Research on Factors Influencing Individual's Behavior of Energy Management

    NASA Astrophysics Data System (ADS)

    Fan, Yanfeng

    With the rapid rise of distributed generation, Internet of Things, and mobile Internet, both U.S. and European smart home manufacturers have developed energy management solutions for individual usage. These applications help people manage their energy consumption more efficiently. Domestic manufacturers have also launched similar products. This paper focuses on the factors influencing Energy Management Behaviour (EMB) at the individual level. By reviewing academic literature, conducting surveys in Beijing, Shanghai and Guangzhou, the author builds an integrated behavioural energy management model of the Chinese energy consumers. This paper takes the vague term of EMB and redefines it as a function of two separate behavioural concepts: Energy Management Intention (EMI), and the traditional Energy Saving Intention (ESI). Secondly, the author conducts statistical analyses on these two behavioural concepts. EMI is the main driver behind an individual's EMB. EMI is affected by Behavioural Attitudes, Subjective Norms, and Perceived Behavioural Control (PBC). Among these three key factors, PBC exerts the strongest influence. This implies that the promotion of the energy management concept is mainly driven by good application user experience (UX). The traditional ESI also demonstrates positive influence on EMB, but its impact is weaker than the impacts arising under EMI's three factors. In other words, the government and manufacturers may not be able to change an individual's energy management behaviour if they rely solely on their traditional promotion strategies. In addition, the study finds that the government may achieve better promotional results by launching subsidies to the manufacturers of these kinds of applications and smart appliances.

  19. Factors influencing the publishing efforts of graduate students in nursing.

    PubMed

    Whitley, G G; Oddi, L F; Terrell, D

    1998-04-01

    The purposes of this study were to identify factors influencing publication efforts of graduate students in nursing and determine the extent to which graduate students' scholarly activities contribute to the creation and dissemination of knowledge in nursing, as evidenced by publication in a professional journal. Authors of articles in Nursing Research were surveyed to assess their status as graduate students during the conceptualization, development, and publication of nursing research studies. The sample consisted of 633 authors of manuscripts published in Nursing Research from 1987 to 1991. The study design was descriptive. A survey questionnaire elicited data on graduate student status and factors that influenced the initiation and completion of the project. The data were analyzed using descriptive statistical techniques. The results of the study suggest that graduate students in nursing make important contributions to the advancement and dissemination of nursing knowledge. Factors that influence graduate students to engage in the process include academic requirements (e.g., thesis, dissertation, coursework), faculty involvement and support, and the ability to self-select the research topic.

  20. System dynamic modelling of industrial growth and landscape ecology in China.

    PubMed

    Xu, Jian; Kang, Jian; Shao, Long; Zhao, Tianyu

    2015-09-15

    With the rapid development of large industrial corridors in China, the landscape ecology of the country is currently being affected. Therefore, in this study, a system dynamic model with multi-dimensional nonlinear dynamic prediction function that considers industrial growth and landscape ecology is developed and verified to allow for more sustainable development. Firstly, relationships between industrial development and landscape ecology in China are examined, and five subsystems are then established: industry, population, urban economy, environment and landscape ecology. The main influencing factors are then examined for each subsystem to establish flow charts connecting those factors. Consequently, by connecting the subsystems, an overall industry growth and landscape ecology model is established. Using actual data and landscape index calculated based on GIS of the Ha-Da-Qi industrial corridor, a typical industrial corridor in China, over the period 2005-2009, the model is validated in terms of historical behaviour, logical structure and future prediction, where for 84.8% of the factors, the error rate of the model is less than 5%, the mean error rate of all factors is 2.96% and the error of the simulation test for the landscape ecology subsystem is less than 2%. Moreover, a model application has been made to consider the changes in landscape indices under four industrial development modes, and the optimal industrial growth plan has been examined for landscape ecological protection through the simulation prediction results over 2015-2020.

  1. Landscape influence on spatial patterns of meningeal worm and liver fluke infection in white-tailed deer.

    PubMed

    Vanderwaal, Kimberly L; Windels, Steve K; Olson, Bryce T; Vannatta, J Trevor; Moen, Ron

    2015-04-01

    Parasites that primarily infect white-tailed deer (Odocoileus virginianus), such as liver flukes (Fascioloides magna) and meningeal worm (Parelaphostrongylus tenuis), can cause morbidity and mortality when incidentally infecting moose (Alces alces). Ecological factors are expected to influence spatial variation in infection risk by affecting the survival of free-living life stages outside the host and the abundance of intermediate gastropod hosts. Here, we investigate how ecology influenced the fine-scale distribution of these parasites in deer in Voyageurs National Park, Minnesota. Deer pellet groups (N = 295) were sampled for the presence of P. tenuis larvae and F. magna eggs. We found that deer were significantly more likely to be infected with P. tenuis in habitats with less upland deciduous forest and more upland mixed conifer forest and shrub, a pattern that mirrored microhabitat differences in gastropod abundances. Deer were also more likely to be infected with F. magna in areas with more marshland, specifically rooted-floating aquatic marshes (RFAMs). The environment played a larger role than deer density in determining spatial patterns of infection for both parasites, highlighting the importance of considering ecological factors on all stages of a parasite's life cycle in order to understand its occurrence within the definitive host.

  2. Genetic Factors Influence Serological Measures of Common Infections

    PubMed Central

    Rubicz, Rohina; Leach, Charles T.; Kraig, Ellen; Dhurandhar, Nikhil V.; Duggirala, Ravindranath; Blangero, John; Yolken, Robert; Göring, Harald H.H.

    2011-01-01

    Background/Aims Antibodies against infectious pathogens provide information on past or present exposure to infectious agents. While host genetic factors are known to affect the immune response, the influence of genetic factors on antibody levels to common infectious agents is largely unknown. Here we test whether antibody levels for 13 common infections are significantly heritable. Methods IgG antibodies to Chlamydophila pneumoniae, Helicobacter pylori, Toxoplasma gondii, adenovirus 36 (Ad36), hepatitis A virus, influenza A and B, cytomegalovirus, Epstein-Barr virus, herpes simplex virus (HSV)-1 and −2, human herpesvirus-6, and varicella zoster virus were determined for 1,227 Mexican Americans. Both quantitative and dichotomous (seropositive/seronegative) traits were analyzed. Influences of genetic and shared environmental factors were estimated using variance components pedigree analysis, and sharing of underlying genetic factors among traits was investigated using bivariate analyses. Results Serological phenotypes were significantly heritable for most pathogens (h2 = 0.17–0.39), except for Ad36 and HSV-2. Shared environment was significant for several pathogens (c2 = 0.10–0.32). The underlying genetic etiology appears to be largely different for most pathogens. Conclusions Our results demonstrate, for the first time for many of these pathogens, that individual genetic differences of the human host contribute substantially to antibody levels to many common infectious agents, providing impetus for the identification of underlying genetic variants, which may be of clinical importance. PMID:21996708

  3. Factors influencing perceived sustainability of Dutch community health programs.

    PubMed

    Vermeer, A J M; Van Assema, P; Hesdahl, B; Harting, J; De Vries, N K

    2015-09-01

    We assessed the perceived sustainability of community health programs organized by local intersectoral coalitions, as well as the factors that collaborating partners think might influence sustainability. Semi-structured interviews were conducted among 31 collaborating partners of 5 community health programs in deprived neighborhoods in the southern part of the Netherlands. The interview guide was based on a conceptual framework that includes factors related to the context, the leading organization, leadership, the coalition, collaborating partners, interventions and outcomes. Interviews were recorded, transcribed and content analyzed using NVivo 8.0. Participants in each of the programs varied in their perceptions of the sustainability of the program, but those people collaborating in pre-existing neighborhood structures expressed relatively high faith in their continuation. The participating citizens in particular believed that these structures would continue to address the health of the community in the future. We found factors from all categories of the conceptual framework that were perceived to influence sustainability. The program leaders appeared to be crucial to the programs, as they were frequently mentioned in close interaction with other factors. Program leaders should use a motivating and supportive leadership style and should act as 'program champions'.

  4. [Landscape classification: research progress and development trend].

    PubMed

    Liang, Fa-Chao; Liu, Li-Ming

    2011-06-01

    Landscape classification is the basis of the researches on landscape structure, process, and function, and also, the prerequisite for landscape evaluation, planning, protection, and management, directly affecting the precision and practicability of landscape research. This paper reviewed the research progress on the landscape classification system, theory, and methodology, and summarized the key problems and deficiencies of current researches. Some major landscape classification systems, e. g. , LANMAP and MUFIC, were introduced and discussed. It was suggested that a qualitative and quantitative comprehensive classification based on the ideology of functional structure shape and on the integral consideration of landscape classification utility, landscape function, landscape structure, physiogeographical factors, and human disturbance intensity should be the major research directions in the future. The integration of mapping, 3S technology, quantitative mathematics modeling, computer artificial intelligence, and professional knowledge to enhance the precision of landscape classification would be the key issues and the development trend in the researches of landscape classification.

  5. The influence of contemporary and historic landscape features on the genetic structure of the sand dune endemic, Cirsium pitcheri (Asteraceae)

    PubMed Central

    Fant, J B; Havens, K; Keller, J M; Radosavljevic, A; Yates, E D

    2014-01-01

    Narrow endemics are at risk from climate change because of their restricted habitat preferences, lower colonization ability and dispersal distances. Landscape genetics combines new tools and analyses that allow us to test how both past and present landscape features have facilitated or hindered previous range expansion and local migration patterns, and thereby identifying potential limitations to future range shifts. We have compared current and historic habitat corridors in Cirsium pitcheri, an endemic of the linear dune ecosystem of the Great Lakes, to determine the relative contributions of contemporary migration and post-glacial range expansion on genetic structure. We used seven microsatellite loci to characterize the genetic structure for 24 populations of Cirsium pitcheri, spanning the center to periphery of the range. We tested genetic distance against different measures of geographic distance and landscape permeability, based on contemporary and historic landscape features. We found moderate genetic structure (Fst=0.14), and a north–south pattern to the distribution of genetic diversity and inbreeding, with northern populations having the highest diversity and lowest levels of inbreeding. High allelic diversity, small average pairwise distances and mixed genetic clusters identified in Structure suggest that populations in the center of the range represent the point of entry to the Lake Michigan and a refugium of diversity for this species. A strong association between genetic distances and lake-level changes suggests that historic lake fluctuations best explain the broad geographic patterns, and sandy habitat best explains local patterns of movement. PMID:24398882

  6. Factors influencing Malaysian public attitudes to agro-biotechnology.

    PubMed

    Amin, Latifah; Ahmad, Jamil; Jahi, Jamaluddin Md; Nor, Abd Rahim Md; Osman, Mohamad; Mahadi, Nor Muhammad

    2011-09-01

    Despite considerable research in advanced countries on public perceptions of and attitudes to modern biotechnology, limited effort has been geared towards developing a structural model of public attitudes to modern biotechnology. The purpose of this paper is to identify the relevant factors influencing public attitudes towards genetically modified (GM) soybean, and to analyze the relationship between all the attitudinal factors. A survey was carried out on 1,017 respondents from various stakeholder groups in the Klang Valley region. Results of the survey have confirmed that attitudes towards complex issues such as biotechnology should be seen as a multifaceted process. The most important factors predicting support for GM soybean are the specific application-linked perceptions about the benefits, acceptance of risk and moral concern while risk and familiarity are significant predictors of benefit and risk acceptance. Attitudes towards GM soybean are also predicted by several general classes of attitude. PMID:22164706

  7. [Factors influencing self-perception of overweight people].

    PubMed

    Makara-Studzińska, Marta; Podstawka, Danuta; Goclon, Karolina

    2013-11-01

    Shaping of self-perception is among others influenced by physical, interpersonal, emotional, and cultural factors. In self-perception of overweight people an important role is played by interpersonal factors, which include the opinions of others and the relationship with the surrounding. The evaluation of the body image is also affect by sociocultural factors including the media, which create an unrealistic and impossible to achieve ideal of beauty. Contemporary ideal of beauty, where a slim figure is dominant, more frequently contributes to the occurrence of discrimination and stigmatization of overweight people. This phenomenon causes negative self-perception leading to the occurrence of such emotional problems as low self-esteem, lack of confidence, depression and anxiety disorders. Overweight children and adolescents are also frequently stigmatized and discriminated because of their body weight, which results in the development of a negative body image that may lead to low self-esteem and symptoms of depression. PMID:24575656

  8. Pharmacokinetic, Pharmacogenetic, and Other Factors Influencing CNS Penetration of Antiretrovirals

    PubMed Central

    Babalola, Chinedum Peace; Morse, Gene D.; Taiwo, Babafemi

    2016-01-01

    Neurological complications associated with the human immunodeficiency virus (HIV) are a matter of great concern. While antiretroviral (ARV) drugs are the cornerstone of HIV treatment and typically produce neurological benefit, some ARV drugs have limited CNS penetration while others have been associated with neurotoxicity. CNS penetration is a function of several factors including sieving role of blood-brain and blood-CSF barriers and activity of innate drug transporters. Other factors are related to pharmacokinetics and pharmacogenetics of the specific ARV agent or mediated by drug interactions, local inflammation, and blood flow. In this review, we provide an overview of the various factors influencing CNS penetration of ARV drugs with an emphasis on those commonly used in sub-Saharan Africa. We also summarize some key associations between ARV drug penetration, CNS efficacy, and neurotoxicity. PMID:27777797

  9. Adolescent risk behaviours and protective factors against peer influence.

    PubMed

    Cattelino, Elena; Glowacz, Fabienne; Born, Michel; Testa, Silvia; Bina, Manuela; Calandri, Emanuela

    2014-12-01

    This study examined the relationships between protective factors and involvement in risk behaviour of Italian adolescents with friends involved in risk. Protective factors were drawn from models of peers and from individual skills (perceived regulatory self-efficacy, intolerant attitudes about deviance) and orientation (to health, school, religion). The data are from two waves, 1 year apart, of a questionnaire survey of adolescents in northwestern Italy. Participants were 908 adolescents (42% boys) ages 14-16 years. Results of a hierarchical regression revealed that religiosity is a protective factor and that friends' models for conventional behaviours and positive attitude about health can mitigate the influence of deviant friends on adolescent risk behaviour 1 year later, even after controlling for prior levels of risk behaviour. Possible implications of this study suggest the importance of implementing preventive interventions by involving the peer group, especially at about 16 years, and working with heterogeneous (deviant and nondeviant) groups. PMID:25448830

  10. Factors influencing Malaysian public attitudes to agro-biotechnology.

    PubMed

    Amin, Latifah; Ahmad, Jamil; Jahi, Jamaluddin Md; Nor, Abd Rahim Md; Osman, Mohamad; Mahadi, Nor Muhammad

    2011-09-01

    Despite considerable research in advanced countries on public perceptions of and attitudes to modern biotechnology, limited effort has been geared towards developing a structural model of public attitudes to modern biotechnology. The purpose of this paper is to identify the relevant factors influencing public attitudes towards genetically modified (GM) soybean, and to analyze the relationship between all the attitudinal factors. A survey was carried out on 1,017 respondents from various stakeholder groups in the Klang Valley region. Results of the survey have confirmed that attitudes towards complex issues such as biotechnology should be seen as a multifaceted process. The most important factors predicting support for GM soybean are the specific application-linked perceptions about the benefits, acceptance of risk and moral concern while risk and familiarity are significant predictors of benefit and risk acceptance. Attitudes towards GM soybean are also predicted by several general classes of attitude.

  11. Influence factors affecting career choice of preclinical medical technology students.

    PubMed

    Gleich, C

    1978-06-01

    Over a seven-year period, data were gathered on 249 declared medical technology majors enrolled in an Introduction to Medical Technology course at the University of Iowa. The Kendall Tau C test for significance (p = less than .05) was utilized in determining the influence of several variables or factors in the students' choice of medical technology as a career. Such factors as the type of work, demand for medical technologists, and desire to help people were found to be highly motivating factors in choice. It appeared the motivation was primarily internalized with assistance sought from various sources. The decision of medical technology as a career was predominantly made in the junior/senior year in high school or freshman/sophomore year in college. PMID:686027

  12. Factors Influencing Learning Environments in an Integrated Experiential Program

    NASA Astrophysics Data System (ADS)

    Koci, Peter

    The research conducted for this dissertation examined the learning environment of a specific high school program that delivered the explicit curriculum through an integrated experiential manner, which utilized field and outdoor experiences. The program ran over one semester (five months) and it integrated the grade 10 British Columbian curriculum in five subjects. A mixed methods approach was employed to identify the students' perceptions and provide richer descriptions of their experiences related to their unique learning environment. Quantitative instruments were used to assess changes in students' perspectives of their learning environment, as well as other supporting factors including students' mindfulness, and behaviours towards the environment. Qualitative data collection included observations, open-ended questions, and impromptu interviews with the teacher. The qualitative data describe the factors and processes that influenced the learning environment and give a richer, deeper interpretation which complements the quantitative findings. The research results showed positive scores on all the quantitative measures conducted, and the qualitative data provided further insight into descriptions of learning environment constructs that the students perceived as most important. A major finding was that the group cohesion measure was perceived by students as the most important attribute of their preferred learning environment. A flow chart was developed to help the researcher conceptualize how the learning environment, learning process, and outcomes relate to one another in the studied program. This research attempts to explain through the consideration of this case study: how learning environments can influence behavioural change and how an interconnectedness among several factors in the learning process is influenced by the type of learning environment facilitated. Considerably more research is needed in this area to understand fully the complexity learning

  13. Factors influencing scores on the Social Responsiveness Scale

    PubMed Central

    Hus, Vanessa; Bishop, Somer; Gotham, Katherine; Huerta, Marisela; Lord, Catherine

    2012-01-01

    Background The Social Responsiveness Scale (SRS) is a parent-completed screening questionnaire often used to measure ASD severity. Although child characteristics are known to influence scores from other ASD-symptom measures, as well as parent-questionnaires more broadly, there has been limited consideration of how non-ASD-specific factors may affect interpretation of SRS scores. Previous studies have explored effects of behavior problems on SRS specificity, but have not addressed influences on the use of the SRS as a quantitative measure of ASD-symptoms. Method Raw scores (SRS-Raw) from parent-completed SRS were analyzed for 2,368 probands with ASD and 1,913 unaffected siblings. Regression analyses were used to assess associations between SRS scores and demographic, language, cognitive, and behavior measures. Results For probands, higher SRS-Raw were associated with greater non-ASD behavior problems, higher age, and more impaired language and cognitive skills, as well as scores from other parent report measures of social development and ASD-symptoms. For unaffected siblings, having more behavior problems predicted higher SRS-Raw; male gender, younger age and poorer adaptive social and expressive communication skills also showed small, but significant effects. Conclusions When using the SRS as a quantitative phenotype measure, the influence of behavior problems, age, and expressive language or cognitive level on scores must be considered. If effects of non-ASD-specific factors are not addressed, SRS scores are more appropriately interpreted as indicating general levels of impairment, than as severity of ASD-specific symptoms or social impairment. Further research is needed to consider how these factors influence the SRS’ sensitivity and specificity in large, clinical samples including individuals with disorders other than ASD. PMID:22823182

  14. Factors influencing smokeless tobacco use in rural Ohio Appalachia.

    PubMed

    Nemeth, Julianna M; Liu, Sherry T; Klein, Elizabeth G; Ferketich, Amy K; Kwan, Mei-Po; Wewers, Mary Ellen

    2012-12-01

    The burden of smokeless tobacco (ST) use disproportionally impacts males in rural Ohio Appalachia. The purpose of this study was to describe the cultural factors contributing to this disparity and to articulate the way in which culture, through interpersonal factors (i.e. social norms and social networks) and community factors (i.e. marketing and availability), impacts ST initiation and use of ST among boys and men in Ohio Appalachia. Fifteen focus groups and 23 individual qualitative interviews were conducted with adult (n = 63) and adolescent (n = 53) residents in Ohio Appalachian counties to ascertain factors associated with ST use and the impact of ST marketing. Transcriptions were independently coded according to questions and themes. ST use appears to be a rite of passage in the development of masculine identity in Ohio Appalachian culture. Interpersonal factors had the greatest influence on initiation and continued use of ST. Ohio Appalachian boys either emulated current ST users or were actively encouraged to use ST through male family and peer networks. Users perceived their acceptance into the male social network as predicated on ST use. Community factors, including ST advertisement and access to ST, reinforced and normalized underlying cultural values. In addition to policy aimed at reducing tobacco marketing and access, interventions designed to reduce ST use in Ohio Appalachia should incorporate efforts to (1) shift the perception of cultural norms regarding ST use and (2) address male social networks as vehicles in ST initiation.

  15. Factors Influencing Smokeless Tobacco Use in Rural Ohio Appalachia

    PubMed Central

    Nemeth, Julianna M.; Liu, Sherry T.; Klein, Elizabeth G.; Ferketich, Amy K.; Kwan, Mei-Po; Wewers, Mary Ellen

    2015-01-01

    Background The burden of smokeless tobacco (ST) use disproportionally impacts males in rural Ohio Appalachia. The purpose of this study was to describe the cultural factors contributing to this disparity and to articulate the way in which culture, through interpersonal factors (i.e. social norms and social networks) and community factors (i.e. marketing and availability), impacts ST initiation and use of ST among boys and men in Ohio Appalachia. Methods Fifteen focus groups and twenty-three individual qualitative interviews were conducted with adult (n=63) and adolescent (n=53) residents in Ohio Appalachian counties to ascertain factors associated with ST use and the impact of ST marketing. Transcriptions were independently coded according to questions and themes. Results ST use appears to be a rite of passage in the development of masculine identity in Ohio Appalachian culture. Interpersonal factors had the greatest influence on initiation and continued use of ST. Ohio Appalachian boys either emulated current ST users or were actively encouraged to use ST through male family and peer networks. Users perceived their acceptance into the male social network as predicated on ST use. Community factors, including ST advertisement and access to ST, reinforced and normalized underlying cultural values. Conclusions In addition to policy aimed at reducing tobacco marketing and access, interventions designed to reduce ST use in Ohio Appalachia should incorporate efforts to 1) shift the perception of cultural norms regarding ST use and 2) address male social networks as vehicles in ST initiation. PMID:22427033

  16. Factors influencing smokeless tobacco use in rural Ohio Appalachia.

    PubMed

    Nemeth, Julianna M; Liu, Sherry T; Klein, Elizabeth G; Ferketich, Amy K; Kwan, Mei-Po; Wewers, Mary Ellen

    2012-12-01

    The burden of smokeless tobacco (ST) use disproportionally impacts males in rural Ohio Appalachia. The purpose of this study was to describe the cultural factors contributing to this disparity and to articulate the way in which culture, through interpersonal factors (i.e. social norms and social networks) and community factors (i.e. marketing and availability), impacts ST initiation and use of ST among boys and men in Ohio Appalachia. Fifteen focus groups and 23 individual qualitative interviews were conducted with adult (n = 63) and adolescent (n = 53) residents in Ohio Appalachian counties to ascertain factors associated with ST use and the impact of ST marketing. Transcriptions were independently coded according to questions and themes. ST use appears to be a rite of passage in the development of masculine identity in Ohio Appalachian culture. Interpersonal factors had the greatest influence on initiation and continued use of ST. Ohio Appalachian boys either emulated current ST users or were actively encouraged to use ST through male family and peer networks. Users perceived their acceptance into the male social network as predicated on ST use. Community factors, including ST advertisement and access to ST, reinforced and normalized underlying cultural values. In addition to policy aimed at reducing tobacco marketing and access, interventions designed to reduce ST use in Ohio Appalachia should incorporate efforts to (1) shift the perception of cultural norms regarding ST use and (2) address male social networks as vehicles in ST initiation. PMID:22427033

  17. Monitoring athletes through self-report: factors influencing implementation.

    PubMed

    Saw, Anna E; Main, Luana C; Gastin, Paul B

    2015-03-01

    Monitoring athletic preparation facilitates the evaluation and adjustment of practices to optimize performance outcomes. Self-report measures such as questionnaires and diaries are suggested to be a simple and cost-effective approach to monitoring an athlete's response to training, however their efficacy is dependent on how they are implemented and used. This study sought to identify the perceived factors influencing the implementation of athlete self-report measures (ASRM) in elite sport settings. Semi-structured interviews were conducted with athletes, coaches and sports science and medicine staff at a national sporting institute (n = 30). Interviewees represented 20 different sports programs and had varying experience with ASRM. Purported factors influencing the implementation of ASRM related to the measure itself (e.g., accessibility, timing of completion), and the social environment (e.g., buy-in, reinforcement). Social environmental factors included individual, inter-personal and organizational levels which is consistent with a social ecological framework. An adaptation of this framework was combined with the factors associated with the measure to illustrate the inter-relations and influence upon compliance, data accuracy and athletic outcomes. To improve implementation of ASRM and ultimately athletic outcomes, a multi-factorial and multi-level approach is needed. Key pointsEffective implementation of a self-report measure for monitoring athletes requires a multi-factorial and multi-level approach which addresses the particular measure used and the surrounding social environment.A well-designed self-report measure should obtain quality data with minimal burden on athletes and staff.A supportive social environment involves buy-in and coordination of all parties, at both an individual and organization level.

  18. Monitoring Athletes Through Self-Report: Factors Influencing Implementation

    PubMed Central

    Saw, Anna E.; Main, Luana C.; Gastin, Paul B.

    2015-01-01

    Monitoring athletic preparation facilitates the evaluation and adjustment of practices to optimize performance outcomes. Self-report measures such as questionnaires and diaries are suggested to be a simple and cost-effective approach to monitoring an athlete’s response to training, however their efficacy is dependent on how they are implemented and used. This study sought to identify the perceived factors influencing the implementation of athlete self-report measures (ASRM) in elite sport settings. Semi-structured interviews were conducted with athletes, coaches and sports science and medicine staff at a national sporting institute (n = 30). Interviewees represented 20 different sports programs and had varying experience with ASRM. Purported factors influencing the implementation of ASRM related to the measure itself (e.g., accessibility, timing of completion), and the social environment (e.g., buy-in, reinforcement). Social environmental factors included individual, inter-personal and organizational levels which is consistent with a social ecological framework. An adaptation of this framework was combined with the factors associated with the measure to illustrate the inter-relations and influence upon compliance, data accuracy and athletic outcomes. To improve implementation of ASRM and ultimately athletic outcomes, a multi-factorial and multi-level approach is needed. Key points Effective implementation of a self-report measure for monitoring athletes requires a multi-factorial and multi-level approach which addresses the particular measure used and the surrounding social environment. A well-designed self-report measure should obtain quality data with minimal burden on athletes and staff. A supportive social environment involves buy-in and coordination of all parties, at both an individual and organization level. PMID:25729301

  19. Factors influencing behavior in the forced swim test.

    PubMed

    Bogdanova, Olena V; Kanekar, Shami; D'Anci, Kristen E; Renshaw, Perry F

    2013-06-13

    The forced swim test (FST) is a behavioral test in rodents which was developed in 1978 by Porsolt and colleagues as a model for predicting the clinical efficacy of antidepressant drugs. A modified version of the FST added the classification of active behaviors into swimming and climbing, in order to facilitate the differentiation between serotonergic and noradrenergic classes of antidepressant drugs. The FST is now widely used in basic research and the pharmaceutical screening of potential antidepressant treatments. It is also one of the most commonly used tests to assess depressive-like behavior in animal models. Despite the simplicity and sensitivity of the FST procedure, important differences even in baseline immobility rates have been reported between different groups, which complicate the comparison of results across studies. In spite of several methodological papers and reviews published on the FST, the need still exists for clarification of factors which can influence the procedure. While most recent reviews have focused on antidepressant effects observed with the FST, this one considers the methodological aspects of the procedure, aiming to summarize issues beyond antidepressant action in the FST. The previously published literature is analyzed for factors which are known to influence animal behavior in the FST. These include biological factors, such as strain, age, body weight, gender and individual differences between animals; influence of preconditioning before the FST: handling, social isolation or enriched environment, food manipulations, various kinds of stress, endocrine manipulations and surgery; schedule and routes of treatment, dosage and type of the drugs as well as experimental design and laboratory environmental effects. Consideration of these factors in planning experiments may result in more consistent FST results.

  20. Factors influencing physicians' knowledge sharing on web medical forums.

    PubMed

    Lin, Tung Cheng; Lai, Ming Cheng; Yang, Shu Wen

    2016-09-01

    Web medical forums are relatively unique as knowledge-sharing platforms because physicians participate exclusively as knowledge contributors and not as knowledge recipients. Using the perspective of social exchange theory and considering both extrinsic and intrinsic motivations, this study aims to elicit the factors that significantly influence the willingness of physicians to share professional knowledge on web medical forums and develops a research model to explore the motivations that underlie physicians' knowledge-sharing attitudes. This model hypothesizes that constructs, including shared vision, reputation, altruism, and self-efficacy, positively influence these attitudes and, by extension, positively impact knowledge-sharing intention. A conventional sampling method and the direct recruitment of physicians at their outpatient clinic gathered valid data from a total of 164 physicians for analysis in the model. The empirical results support the validity of the proposed model and identified shared vision as the most significant factor of influence on knowledge-sharing attitudes, followed in descending order by knowledge-sharing self-efficacy, reputation, and altruism. PMID:25888432

  1. [Factors influencing psychotherapeutic treatment outcome of various syndromes].

    PubMed

    Hartmann, Sebastian; Zepf, Siegfried

    2004-12-01

    The authors investigated specific and unspecific factors influencing the psychotherapeutic treatment of various syndromes using a questionnaire which systematically replicated the Consumer Reports Study performed in the USA in 1994. The authors were particularly concerned with the degree to which certain psychotherapeutic methods - psychoanalysis, depth psychology-based psychotherapy and behavioral therapy - produced differing results following treatment of syndromes. Using cluster-analysis, two groups of syndromes could be distinguished: Patients with depressive symptoms, stress-related disorders and/or relationship problems (depression-group) and patients with anxiety disorders and/or eating-related disorders (anxiety-group). With the help of cart-analysis (Classification and Regression Trees) it was possible to identify factors influencing the improvement of symptoms. The method of treatment had not a specific effect on the improvement of symptoms. In both groups the most important predictor was the length of treatment. Furthermore in the depression group the sex of the patients and a possible restriction of the treatment by the health insurance companies influenced the treatment results and in the anxiety group the frequency of treatment and the age of the patients. PMID:15551189

  2. High Enrollment Course Success Factors in Virtual School: Factors Influencing Student Academic Achievement

    ERIC Educational Resources Information Center

    Liu, Feng; Cavanaugh, Cathy

    2011-01-01

    This paper describes a study of success factors in high enrollment courses in a K-12 virtual school learning environment. The influence of variables: time student spent in the learning management system (LMS), number of times logged into the LMS, teacher comment, participation in free or reduced lunch programs, student status in the virtual school…

  3. Landscape evolution (A Review)

    PubMed Central

    Sharp, Robert P.

    1982-01-01

    Landscapes are created by exogenic and endogenic processes acting along the interface between the lithosphere and the atmosphere and hydrosphere. Various landforms result from the attack of weathering and erosion upon the highly heterogeneous lithospheric surface. Landscapes are dynamic, acutely sensitive to natural and artificial perturbation. Undisturbed, they can evolve through a succession of stages to a plain of low relief. Often, the progression of an erosion cycle is interrupted by tectonic or environmental changes; thus, many landscapes preserve vestiges of earlier cycles useful in reconstructing the recent history of Earth's surface. Landforms are bounded by slopes, so their evolution is best understood through study of slopes and the complex of factors controlling slope character and development. The substrate, biosphere, climatic environment, and erosive processes are principal factors. Creep of the disintegrated substrate and surface wash by water are preeminent. Some slopes attain a quasisteady form and recede parallel to themselves (backwearing); others become ever gentler with time (downwearing). The lovely convex/rectilinear/concave profile of many debris-mantled slopes reflects an interplay between creep and surface wash. Landscapes of greatest scenic attraction are usually those in which one or two genetic factors have strongly dominated or those perturbed by special events. Nature has been perturbing landscapes for billions of years, so mankind can learn about landscape perturbation from natural examples. Images

  4. Aeolian Coastal Landscapes in changes (a study from Tahkuna, Estonia)

    NASA Astrophysics Data System (ADS)

    Anderson, A.

    2012-04-01

    The openness of the coast to the winds and storm waves has an important part in changing aeolian coastal landscapes as well as anthropogenic factor. The aeolian coastal landscapes are probably the most dynamic areas. Occurrence of aeolian coastal landscapes in Estonia is limited. They consist of sandy beaches, sandy beach ridges and dunes. The coastal ecosystems are strongly affected by their topography, based on the character of deposits and moisture conditions. The majority of their ecosystems are quite close to the specific natural habitat. These ecosystems are represented in the list of the European Union Habitats (Natura 2000). In recent decades human influence has changed the landscape over time in different activities (recreation, trampling, off-road driving) and their intensities, which has led to destruction or degradation of various habitats. Previously coastal landscapes were used for forestry and pasture. Nowadays one of the most serious threats to open landscape is afforestation. This study examines the relationships between landscape components during last decades. Trying to find out how much aeolian coastal landscapes are influenced by natural processes or human activities. The results are based on cartographic analysis, fieldwork data. The method of landscape complex profile was used. The profiles show a cross-sections of landforms and interrelationships between landscape components, most frequently describing the relations between soils and vegetation. In each sample point the mechanical composition of sediments, vegetation cover and soil is determined. Results show that changes in landscapes are induced by their own development as well as changes in environmental factors and human activities. Larger changes are due to increase of coastal processes activity. These processes can be observed in sandy beaches, which are easily transformed by waves. Higher sea levels during storm surges are reaching older beach formation, causing erosion and creating

  5. Influencing factors of transient elastography in detecting liver stiffness

    PubMed Central

    Shan, Rong; Yin, Hong; Yang, Wenjuan; Li, Jianzhi; Zhang, Meifang; Zhao, Min; Shao, Jiang; Wang, Aiguang

    2016-01-01

    Liver stiffness, which correlates well with liver fibrosis stage, can be measured noninvasively by transient elastography, also known as Fibroscan. The present study aimed to determine the independent factors influencing Fibroscan detection by multiple regression analysis. A total of 181 patients who required liver biopsy were enrolled. Liver stiffness measurement (LSM) was detected by Fibroscan on the day of liver biopsy, while clinical information and routine biochemical examination results were also collected. Correlation was analyzed by Spearman's correlation, and multiple regression analysis was performed to analyze the independent influencing factors. The results demonstrated that platelet (PLT) levels, serum albumin (ALB), prothrombin activity (PTA) and body mass index (BMI) were independent predictors of liver stiffness. The contribution of these four predictors to the regression equation was in the following descending order: PLT (negative correlation) > ALB (negative correlation) > PTA (negative correlation) > BMI (positive correlation). In conclusion, the parameters of PLT, ALB, PTA and BMI are independent predicting factors affecting Fibroscan detection. Therefore, the diagnosis and evaluation of liver fibrosis should comprehensively consider the results of Fibroscan, and clinical and laboratory examinations.

  6. A Broad Set of Chromatin Factors Influences Splicing

    PubMed Central

    Allemand, Eric; Myers, Michael P.; Garcia-Bernardo, Jose; Harel-Bellan, Annick; Krainer, Adrian R.; Muchardt, Christian

    2016-01-01

    Several studies propose an influence of chromatin on pre-mRNA splicing, but it is still unclear how widespread and how direct this phenomenon is. We find here that when assembled in vivo, the U2 snRNP co-purifies with a subset of chromatin-proteins, including histones and remodeling complexes like SWI/SNF. Yet, an unbiased RNAi screen revealed that the outcome of splicing is influenced by a much larger variety of chromatin factors not all associating with the spliceosome. The availability of this broad range of chromatin factors impacting splicing further unveiled their very context specific effect, resulting in either inclusion or skipping, depending on the exon under scrutiny. Finally, a direct assessment of the impact of chromatin on splicing using an in vitro co-transcriptional splicing assay with pre-mRNAs transcribed from a nucleosomal template, demonstrated that chromatin impacts nascent pre-mRNP in their competence for splicing. Altogether, our data show that numerous chromatin factors associated or not with the spliceosome can affect the outcome of splicing, possibly as a function of the local chromatin environment that by default interferes with the efficiency of splicing. PMID:27662573

  7. Influencing factors of mental health of medical students in China.

    PubMed

    Yang, Fan; Meng, Heng; Chen, Hui; Xu, Xin-hao; Liu, Zhuo; Luo, Ai; Feng, Zhan-chun

    2014-06-01

    This study investigated the mental health status of medical students in China, and analyzed the influencing factors in order to provide evidence for mental health education for medical students. A stratified cluster sampling method was used to recruit medical students from Huazhong University of Science and Technology, China. The questionnaire survey on general information and Symptom Checklist 90 (SCL-90) were used for investigation and analysis. The results showed among the 1137 valid questionnaires, 278 (24.45%) participants had SCL-90 score ≥ 160. The top three mental problems of medical students were obsessive-compulsive disorder, interpersonal sensitivity and depression in terms of the factor score ≥ 2.5 and the number of participants who reflected on the diseases. The third-year medical students had the worst mental health status, and fifth-year medical students had the best mental health status. Students from rural area had more psychological problems than those from urban area; furthermore, students with high professional satisfaction, those who were the single child of the family, non-poor students, and those whose parents had high education level had better mental health status. It was concluded that the mental health of medical students is not optimistic in China. Medical students have some mental health problems of different degrees. Factors that influence the mental health of medical students include academic pressure, professional satisfaction level and family environment.

  8. Expecting success: Factors influencing ninth graders' science self-efficacy

    NASA Astrophysics Data System (ADS)

    Donahue, Elizabeth

    What factors influence ninth grade students' expectations for success in science? Using social cognitive theory and bioecological systems theory as theoretical frameworks, this dissertation employs data from the High School Longitudinal Study of 2009 (HSLS:09) to examine the relative impact of teacher practices and their perceived attitudes on students' science self-efficacy. Further, as they relate to this broader issue, the relative impact of student subjective task value and teacher characteristics is also investigated. It has been well documented that U.S. students are not achieving at satisfactory levels in science. Education policy has focused on improving science teacher quality as one way to address this problem. Teacher effectiveness has been primarily measured by student achievement on standardized tests. However, not enough attention has been given to the social cognitive factors that can lead to increased achievement and persistence in science as well as how teachers may influence these factors. This study interrogates the relationship between student and teacher variables and the social cognitive construct of self-efficacy, which has proven to have a significant impact on student achievement and persistence in science. Findings add to the current literature surrounding ways that educators may increase student performance in science by employing policies and practices that benefit the development of student science self-efficacy.

  9. Factors influencing quality of bowel preparation for colonoscopy.

    PubMed

    Romero, Ronald V; Mahadeva, Sanjiv

    2013-02-16

    Recent technological advances in colonoscopy have led to improvements in both image enhancement and procedural performance. However, the utility of these technological advancements remain dependent on the quality of bowel preparation during colonoscopy. Poor bowel preparation has been shown to be associated with lower quality indicators of colonoscopy performance, such as reduced cecal intubation rates, increased patient discomfort and lower adenoma detection. The most popular bowel preparation regimes currently used are based on either Polyethylene glycol-electrolyte, a non-absorbable solution, or aqueous sodium phosphate, a low-volume hyperosmotic solution. Statements from various international societies and several reviews have suggested that the efficacy of bowel preparation regimes based on both purgatives are similar, although patients' compliance with these regimes may differ somewhat. Many studies have now shown that factors other than the type of bowel preparation regime used, can influence the quality of bowel preparation among adult patients undergoing colonoscopy. These factors can be broadly categorized as either patient-related or procedure-related. Studies from both Asia and the West have identified patient-related factors such as an increased age, male gender, presence of co-morbidity and socio-economic status of patients to be associated with poor bowel preparation among adults undergoing routine out-patient colonoscopy. Additionally, procedure-related factors such as adherence to bowel preparation instructions, timing of bowel purgative administration and appointment waiting times for colonoscopy are recognized to influence the quality of colon cleansing. Knowledge of these factors should aid clinicians in modifying bowel preparation regimes accordingly, such that the quality of colonoscopy performance and delivery of service to patients can be optimised.

  10. Factors Influencing the Management of Unruptured Intracranial Aneurysms.

    PubMed

    Gillani, Rebecca L; Podraza, Katherine M; Luthra, Nijee; Origitano, Thomas C; Schneck, Michael J

    2016-01-01

    Background Deciding how to manage an unruptured intracranial aneurysm can be difficult for patients and physicians due to controversies about management. The decision as to when and how to intervene may be variable depending on physicians' interpretation of available data regarding natural history and morbidity and mortality of interventions. Another significant factor in the decision process is the patients' conception of the risks of rupture and interventions and the psychological burden of harboring an unruptured intracranial aneurysm. Objective  To describe which factors are being considered when patients and their physicians decide how to manage unruptured intracranial aneurysms.  Materials & methods  In a retrospective chart review study, we identified patients seen for evaluation of an unruptured intracranial aneurysm. Data was collected regarding patient and aneurysm characteristics. The physician note pertaining to the management decision was reviewed for documented reasons for intervention. Results  Of 88 patients included, 36 (41%) decided to undergo open or endovascular surgery for at least one unruptured intracranial aneurysm. Multiple aneurysms were present in 14 (16%) patients. Younger patients and current smokers were more likely to undergo surgery, but gender and race did not affect management. Aneurysm size and location strongly influenced management. The most common documented reasons underlying the decision of whether to intervene were the risk of rupture, aneurysm size, and risks of the procedure. For 23 aneurysms (21%), there were no factors documented for the management decision.  Conclusion  The risk of rupture of unruptured intracranial aneurysms may be underestimated by currently available natural history data. Major factors weighed by physicians in management decisions include aneurysm size and location, the patient's age, and medical comorbidities along with the risk of procedural complications. Additional data is needed to define

  11. Training community health workers: factors that influence mammography use.

    PubMed

    Kratzke, Cynthia; Garzon, Laurel; Lombard, John; Karlowicz, Karen

    2010-12-01

    The purpose of this study was to assess factors that influence mammography use among volunteer community health workers (CHWs). Data trends indicate lower mammography rates among minority and low-income women. Although CHW interventions have been shown to promote mammography use among this population, training strategies and the use of a comprehensive needs assessment are lacking. Using a cross-sectional study design, data were collected via a mailed survey. The dependent variable was mammography use within the past 2 years. The independent variables were categorized according to the factors in the PRECEDE-PROCEED model. Predisposing factors included susceptibility, barriers, benefits, health motivation, self-efficacy, education, and age. Enabling factors included income, health insurance, and regular source of care. Reinforcing factors included physician recommendation to get a mammogram, social norms, and family history of breast cancer. Self-reported data from a mailed survey were obtained from a convenience sample of urban CHWS (N = 109) ages 40-73 with a mean age of 55 (SD = 9.43). The sample included 90% African American and 8% White women. Logistic regression results showed barriers to be predictive of mammography use among CHWs controlling for age, self-efficacy, health motivation, and social norms. The findings suggest CHW training focus on how to identify and address barriers to increase the likelihood of mammography use among CHWs. Future research is needed to identify cultural differences in barriers for minority CHWs.

  12. Factors influencing reductions in smoking among Australian adolescents.

    PubMed

    Dessaix, Anita; Maag, Audrey; McKenzie, Jeanie; Currow, David C

    2016-01-01

    A continued increase in the proportion of adolescents who never smoke, as well as an understanding of factors that influence reductions in smoking among this susceptible population, is crucial. The World Health Organization Framework Convention on Tobacco Control provides an appropriate structure to briefly examine Australian and New South Wales policies and programs that are influencing reductions in smoking among adolescents in Australia. This paper provides an overview of price and recent tax measures to reduce the demand for tobacco, the evolution of smoke-free environment policies, changes to tobacco labelling and packaging, public education campaigns, and restrictions to curb tobacco advertising. It also discusses supplyreduction measures that limit adolescents' access to tobacco products. Consideration is given to emerging priorities to achieve continued declines in smoking by Australian adolescents. PMID:26863168

  13. The influence of landscape configuration and environment on population genetic structure in a sedentary passerine: insights from loci located in different genomic regions.

    PubMed

    Ferrer, E S; García-Navas, V; Bueno-Enciso, J; Barrientos, R; Serrano-Davies, E; Cáliz-Campal, C; Sanz, J J; Ortego, J

    2016-01-01

    The study of the factors structuring genetic variation can help to infer the neutral and adaptive processes shaping the demographic and evolutionary trajectories of natural populations. Here, we analyse the role of isolation by distance (IBD), isolation by resistance (IBR, defined by landscape composition) and isolation by environment (IBE, estimated as habitat and elevation dissimilarity) in structuring genetic variation in 25 blue tit (Cyanistes caeruleus) populations. We typed 1385 individuals at 26 microsatellite loci classified into two groups by considering whether they are located into genomic regions that are actively (TL; 12 loci) or not (NTL; 14 loci) transcribed to RNA. Population genetic differentiation was mostly detected using the panel of NTL. Landscape genetic analyses showed a pattern of IBD for all loci and the panel of NTL, but genetic differentiation estimated at TL was only explained by IBR models considering high resistance for natural vegetation and low resistance for agricultural lands. Finally, the absence for IBE suggests a lack of divergent selection pressures associated with differences in habitat and elevation. Overall, our study shows that markers located in different genomic regions can yield contrasting inferences on landscape-level patterns of realized gene flow in natural populations.

  14. High spatial resolution WorldView-2 imagery for mapping NDVI and its relationship to temporal urban landscape evapotranspiration factors

    USGS Publications Warehouse

    Nouri, Hamideh; Beecham, Simon; Anderson, Sharolyn; Nagler, Pamela

    2014-01-01

    Evapotranspiration estimation has benefitted from recent advances in remote sensing and GIS techniques particularly in agricultural applications rather than urban environments. This paper explores the relationship between urban vegetation evapotranspiration (ET) and vegetation indices derived from newly-developed high spatial resolution WorldView-2 imagery. The study site was Veale Gardens in Adelaide, Australia. Image processing was applied on five images captured from February 2012 to February 2013 using ERDAS Imagine. From 64 possible two band combinations of WorldView-2, the most reliable one (with the maximum median differences) was selected. Normalized Difference Vegetation Index (NDVI) values were derived for each category of landscape cover, namely trees, shrubs, turf grasses, impervious pavements, and water bodies. Urban landscape evapotranspiration rates for Veale Gardens were estimated through field monitoring using observational-based landscape coefficients. The relationships between remotely sensed NDVIs for the entire Veale Gardens and for individual NDVIs of different vegetation covers were compared with field measured urban landscape evapotranspiration rates. The water stress conditions experienced in January 2013 decreased the correlation between ET and NDVI with the highest relationship of ET-Landscape NDVI (Landscape Normalized Difference Vegetation Index) for shrubs (r2 = 0.66) and trees (r2 = 0.63). However, when the January data was excluded, there was a significant correlation between ET and NDVI. The highest correlation for ET-Landscape NDVI was found for the entire Veale Gardens regardless of vegetation type (r2 = 0.95, p > 0.05) and the lowest one was for turf (r2 = 0.88, p > 0.05). In support of the feasibility of ET estimation by WV2 over a longer period, an algorithm recently developed that estimates evapotranspiration rates based on the Enhanced Vegetation Index (EVI) from MODIS was employed. The results revealed a significant positive

  15. Factors influencing stakeholders attitudes toward genetically modified aedes mosquito.

    PubMed

    Amin, Latifah; Hashim, Hasrizul

    2015-06-01

    Dengue fever is a debilitating and infectious disease that could be life-threatening. It is caused by the dengue virus which affects millions of people in the tropical area. Currently, there is no cure for the disease as there is no vaccine available. Thus, prevention of the vector population using conventional methods is by far the main strategy but has been found ineffective. A genetically modified (GM) mosquito is among the favoured alternatives to curb dengue fever in Malaysia. Past studies have shown that development and diffusion of gene technology products depends heavily upon public acceptance. The purpose of this study is to identify the relevant factors influencing stakeholders' attitudes toward the GM Aedes mosquito and to analyse the relationships between all the factors using the structural equation model. A survey was carried out on 509 respondents from various stakeholder groups in the Klang Valley region of Malaysia. Results of the survey have confirmed that public perception towards complex issues such as gene technology should be seen as a multi-faceted process. The perceived benefit-perceived risk balance is very important in determining the most predominant predictor of attitudes toward a GM mosquito. In this study the stakeholders perceived the benefit of the GM mosquito as outweighing its risk, translating perceived benefit as the most important direct predictor of attitudes toward the GM mosquito. Trust in key players has a direct influence on attitudes toward the GM mosquito while moral concern exhibited an indirect influence through perceived benefits. Other factors such as attitudes toward technology and nature were also indirect predictors of attitudes toward the GM mosquito while religiosity and engagement did not exhibited any significant roles. The research findings serve as a useful database to understand public acceptance and the social construct of public attitudes towards the GM mosquito to combat dengue. PMID:24906652

  16. Factors influencing outcome of pregnancy in heavy-drinking women.

    PubMed

    Qazi, Q H; Chua, A; Milman, D; Solish, G

    1982-01-01

    18 pregnant women identified as heavy drinkers by the criteria of Cahalan et al., gave birth to 6 normal infants, 5 infants with fetal alcohol syndrome (FAS) and 7 with partial FAS. Average daily alcohol consumption of mothers of normal infants was less than that of mothers of FAS and partial FAS infants. Lower socioeconomic class, higher parity and increased use of tobacco and other drugs were non-alcohol-related maternal factors which appeared to influence the outcome of pregnancy in heavy-drinking women.

  17. Manual flying skills under the influence of performance shaping factors.

    PubMed

    Haslbeck, Andreas; Schubert, Ekkehart; Onnasch, Linda; Hüttig, Gerhard; Bubb, Heiner; Bengler, Klaus

    2012-01-01

    This paper describes an experimental study investigating pilots' manual flying skills. In today's line oriented flight training, basic flying skills are neglected frequently. So, the study examines the manual flying skills of commercial airline pilots under the influence of several performance shaping factors like training, practice or fatigue in a landing scenario. The landing phase shows a disproportionate high percentage of aircraft accidents and it is typically flown by hand. The study is to be undertaken with randomly selected pilots in a full motion flight simulator to ensure a high validity of the results. PMID:22316719

  18. Factors influencing trace element composition in human teeth

    SciTech Connect

    Tandon, L.; Iyengar, G.V.

    1997-12-01

    The authors recently compiled and reviewed the literature published in or after 1978 for 45 major, minor, and trace elements in human teeth as a part of an International Atomic Energy Agency (IAEA) study. The purpose of this paper is to discuss the various factors that influence the concentration levels of certain trace elements in human teeth. The sampling practices and analytical techniques that are applicable for trace element analysis are also discussed. It is also our intention to identify reference range of values, where data permit such conclusions. The scrutiny was designed to identify only the healthy permanent teeth, and values from teeth with fillings, caries, or periodontal diseases were eliminated.

  19. Influence of trees in the landscape on parasitism rates of grassland passerine nests in Southeastern North Dakota

    USGS Publications Warehouse

    Pietz, P.J.; Buhl, D.A.; Shaffer, J.A.; Winter, M.; Johnson, D.H.

    2009-01-01

    Woody vegetation has been linked to increased rates of Brown-headed Cowbird (Molothrus ater) parasitism for some grassland hosts. In northern North Dakota, however, studies reported that parasitism of grassland passerine nests was lower in landscapes with trees than in those without trees. We looked for evidence of this pattern elsewhere, using data from two studies conducted on the Sheyenne National Grassland in southeastern North Dakota. Specifically, we examined the probability of parasitism relative to percent tree cover within 2 km of a nest. We found a negative relationship for grassland passerine nests of all species tested. Our results support the suggestion that cowbirds are less likely to parasitize nests of grassland passerines where tree cover on the landscape is greater. This pattern could be explained by cowbirds switching to alternative hosts in woodlands, but this hypothesis needs further testing. ?? 2009 by The Cooper Ornithological Society. All rights reserved.

  20. Human-Induced Changes in Landscape Configuration Influence Individual Movement Routines: Lessons from a Versatile, Highly Mobile Species

    PubMed Central

    Camacho, Carlos; Palacios, Sebastián; Sáez, Pedro; Sánchez, Sonia; Potti, Jaime

    2014-01-01

    Landscape conversion by humans may have detrimental effects on animal populations inhabiting managed ecosystems, but human-altered areas may also provide suitable environments for tolerant species. We investigated the spatial ecology of a highly mobile nocturnal avian species–the red-necked nightjar (Caprimulgus ruficollis)–in two contrastingly managed areas in Southwestern Spain to provide management recommendations for species having multiple habitat requirements. Based on habitat use by radiotagged nightjars, we created maps of functional heterogeneity in both areas so that the movements of breeding individuals could be modeled using least-cost path analyses. In both the natural and the managed area, nightjars used remnants of native shrublands as nesting sites, while pinewood patches (either newly planted or natural mature) and roads were selected as roosting and foraging habitats, respectively. Although the fraction of functional habitat was held relatively constant (60.9% vs. 74.1% in the natural and the managed area, respectively), landscape configuration changed noticeably. As a result, least-cost routes (summed linear distances) from nest locations to the nearest roost and foraging sites were three times larger in the natural than in the managed area (mean ± SE: 1356±76 m vs. 439±32 m). It seems likely that the increased proximity of functional habitats in the managed area relative to the natural one is underlying the significantly higher abundances of nightjars observed therein, where breeders should travel shorter distances to link together essential resources, thus likely reducing their energy expenditure and mortality risks. Our results suggest that landscape configuration, but not habitat availability, is responsible for the observed differences between the natural and the managed area in the abundance and movements of breeding nightjars, although no effect on body condition was detected. Agricultural landscapes could be moderately managed to

  1. Influence of connectivity, wild prey and disturbance on occupancy of tigers in the human-dominated western Terai Arc Landscape.

    PubMed

    Harihar, Abishek; Pandav, Bivash

    2012-01-01

    Occupying only 7% of their historical range and confined to forested habitats interspersed in a matrix of human dominated landscapes, tigers (Panthera tigris) typify the problems faced by most large carnivores worldwide. With heads of governments of tiger range countries pledging to reverse the extinction process and setting a goal of doubling wild tiger numbers by 2022, achieving this target would require identifying existing breeding cores, potential breeding habitats and opportunities for dispersal. The Terai Arc Landscape (TAL) represents one region which has recently witnessed recovery of tiger populations following conservation efforts. In this study, we develop a spatially explicit tiger occupancy model with survey data from 2009-10 based on a priori knowledge of tiger biology and specific issues plaguing the western TAL (6,979 km(2)), which occurs in two disjunct units (Tiger Habitat Blocks; THBs). Although the overall occupancy of tigers was 0.588 (SE 0.071), our results clearly indicate that loss in functionality of a regional corridor has resulted in tigers now occupying 17.58% of the available habitat in THB I in comparison to 88.5% in THB II. The current patterns of occupancy were best explained by models incorporating the interactive effect of habitat blocks (AIC w = 0.883) on wild prey availability (AIC w = 0.742) and anthropogenic disturbances (AIC w = 0.143). Our analysis has helped identify areas of high tiger occupancy both within and outside existing protected areas, which highlights the need for a unified control of the landscape under a single conservation unit with the primary focus of managing tigers and associated wildlife. Finally, in the light of global conservation targets and recent legislations in India, our study assumes significance as we identify opportunities to secure (e.g. THB II) and increase (e.g. THB I) tiger populations in the landscape.

  2. Human-induced changes in landscape configuration influence individual movement routines: lessons from a versatile, highly mobile species.

    PubMed

    Camacho, Carlos; Palacios, Sebastián; Sáez, Pedro; Sánchez, Sonia; Potti, Jaime

    2014-01-01

    Landscape conversion by humans may have detrimental effects on animal populations inhabiting managed ecosystems, but human-altered areas may also provide suitable environments for tolerant species. We investigated the spatial ecology of a highly mobile nocturnal avian species-the red-necked nightjar (Caprimulgus ruficollis)-in two contrastingly managed areas in Southwestern Spain to provide management recommendations for species having multiple habitat requirements. Based on habitat use by radiotagged nightjars, we created maps of functional heterogeneity in both areas so that the movements of breeding individuals could be modeled using least-cost path analyses. In both the natural and the managed area, nightjars used remnants of native shrublands as nesting sites, while pinewood patches (either newly planted or natural mature) and roads were selected as roosting and foraging habitats, respectively. Although the fraction of functional habitat was held relatively constant (60.9% vs. 74.1% in the natural and the managed area, respectively), landscape configuration changed noticeably. As a result, least-cost routes (summed linear distances) from nest locations to the nearest roost and foraging sites were three times larger in the natural than in the managed area (mean ± SE: 1356±76 m vs. 439±32 m). It seems likely that the increased proximity of functional habitats in the managed area relative to the natural one is underlying the significantly higher abundances of nightjars observed therein, where breeders should travel shorter distances to link together essential resources, thus likely reducing their energy expenditure and mortality risks. Our results suggest that landscape configuration, but not habitat availability, is responsible for the observed differences between the natural and the managed area in the abundance and movements of breeding nightjars, although no effect on body condition was detected. Agricultural landscapes could be moderately managed to

  3. Influence of Connectivity, Wild Prey and Disturbance on Occupancy of Tigers in the Human-Dominated Western Terai Arc Landscape

    PubMed Central

    Harihar, Abishek; Pandav, Bivash

    2012-01-01

    Occupying only 7% of their historical range and confined to forested habitats interspersed in a matrix of human dominated landscapes, tigers (Panthera tigris) typify the problems faced by most large carnivores worldwide. With heads of governments of tiger range countries pledging to reverse the extinction process and setting a goal of doubling wild tiger numbers by 2022, achieving this target would require identifying existing breeding cores, potential breeding habitats and opportunities for dispersal. The Terai Arc Landscape (TAL) represents one region which has recently witnessed recovery of tiger populations following conservation efforts. In this study, we develop a spatially explicit tiger occupancy model with survey data from 2009–10 based on a priori knowledge of tiger biology and specific issues plaguing the western TAL (6,979 km2), which occurs in two disjunct units (Tiger Habitat Blocks; THBs). Although the overall occupancy of tigers was 0.588 (SE 0.071), our results clearly indicate that loss in functionality of a regional corridor has resulted in tigers now occupying 17.58% of the available habitat in THB I in comparison to 88.5% in THB II. The current patterns of occupancy were best explained by models incorporating the interactive effect of habitat blocks (AIC w = 0.883) on wild prey availability (AIC w = 0.742) and anthropogenic disturbances (AIC w = 0.143). Our analysis has helped identify areas of high tiger occupancy both within and outside existing protected areas, which highlights the need for a unified control of the landscape under a single conservation unit with the primary focus of managing tigers and associated wildlife. Finally, in the light of global conservation targets and recent legislations in India, our study assumes significance as we identify opportunities to secure (e.g. THB II) and increase (e.g. THB I) tiger populations in the landscape. PMID:22792220

  4. Influence of connectivity, wild prey and disturbance on occupancy of tigers in the human-dominated western Terai Arc Landscape.

    PubMed

    Harihar, Abishek; Pandav, Bivash

    2012-01-01

    Occupying only 7% of their historical range and confined to forested habitats interspersed in a matrix of human dominated landscapes, tigers (Panthera tigris) typify the problems faced by most large carnivores worldwide. With heads of governments of tiger range countries pledging to reverse the extinction process and setting a goal of doubling wild tiger numbers by 2022, achieving this target would require identifying existing breeding cores, potential breeding habitats and opportunities for dispersal. The Terai Arc Landscape (TAL) represents one region which has recently witnessed recovery of tiger populations following conservation efforts. In this study, we develop a spatially explicit tiger occupancy model with survey data from 2009-10 based on a priori knowledge of tiger biology and specific issues plaguing the western TAL (6,979 km(2)), which occurs in two disjunct units (Tiger Habitat Blocks; THBs). Although the overall occupancy of tigers was 0.588 (SE 0.071), our results clearly indicate that loss in functionality of a regional corridor has resulted in tigers now occupying 17.58% of the available habitat in THB I in comparison to 88.5% in THB II. The current patterns of occupancy were best explained by models incorporating the interactive effect of habitat blocks (AIC w = 0.883) on wild prey availability (AIC w = 0.742) and anthropogenic disturbances (AIC w = 0.143). Our analysis has helped identify areas of high tiger occupancy both within and outside existing protected areas, which highlights the need for a unified control of the landscape under a single conservation unit with the primary focus of managing tigers and associated wildlife. Finally, in the light of global conservation targets and recent legislations in India, our study assumes significance as we identify opportunities to secure (e.g. THB II) and increase (e.g. THB I) tiger populations in the landscape. PMID:22792220

  5. Factors Influencing Dating Experiences Among African American Emerging Adults

    PubMed Central

    Hall, Naomi M.; Lee, Anna K.; Witherspoon, Daphne D.

    2014-01-01

    This study examined sociocultural factors that impact dating and sexual experiences of heterosexual African American undergraduate college students attending a historically Black institution in the Southeastern United States. Specifically, mate availability and relationship involvement were analyzed to document students’ experiences, and how these influences may be associated with sexual decision making and behavior. Data from nine focus groups (N = 57) were aggregated and four subthemes were identified: competition among women, acceptability of mates, high prevalence of casual relationships, and lowered expectations for commitment. Power dynamics emerged as a contributing factor to the types of relationship involvement, sexual decision-making, and behavior among participants. The importance of prevention programs focusing on situational and cultural variables is highlighted. Additionally, implications for professionals working with emerging adults to consider the impact of the gender ratio imbalance, and perceived power distributions on perceptions of dating relationships, and sexual decision making and behavior are addressed. PMID:25530924

  6. The influence of landscape design on soil erosion in the Chernozem region of the South-West Foreland of the West Carpathians in the Medevial to Modern Times and po-collectivization periods

    NASA Astrophysics Data System (ADS)

    Smetanová, Anna; Verstraeten, Gert; Nyens, Gerda; Notebaert, Bastiaan; Szwarczewski, Piotr; Čurlík, Ján; Burian, Libor; Kazeminejad, Seyed Ali; Létal, Aleš; Dotterweich, Markus

    2015-04-01

    Since the onset of agriculture the erosion processes - water, tillage and wind erosion - have dominated the soil degradation and the loss of soil resources in the agricultural landscapes worldwide. Their influence has varied within time and spatial scales according to changing environmental and societal factors, including human-induced landscape design. The Holocene landforms transformation in a zero-order catchment of a dry valley (0.28 km2) in the Chernozem region of the South-West Foreland of the West Carpathians was studied. The analyses of geoarchives and spatial patterns of soil profile truncation and colluviation were performed and the historical field border structure reconstructed. The results showed strong relationship between the long-term soil erosion pattern and landscape sructure in areas with stable historical landscape structure. It favored the prevalence of tillage erosion and tillage induced soil translocation and minimized the fluxes and sediment delivery of wind and water erosion. The erosion of the entire 0,6 m thick humus horizon by tillage was documented during historical times. The intensification of agriculture since the mid -18th Century led to the change in field borders and thus shifted the long-term fluxes of soil translocation. The most profound changes were connected to the collectivization of agriculture since 1950's, when the entire catchment became part of one field and heavy machinery started to be applied. The general contour direction of the tillage decreased locally the down-slope tillage translocation, but became parallel to flow direction in the valley bottom and to the two main dominant wind directions. The areas with a significant proportion of parent material (loess) in the tillage horizon increased almost four-fold in 50 years. They are similarly to the older ones localized in the upper-slope position, but they spread to concavities and less steep slope gradients. It implied that the change of tillage direction in

  7. Factors That Influence the Extensional Rheological Property of Saliva.

    PubMed

    Vijay, Amrita; Inui, Taichi; Dodds, Michael; Proctor, Gordon; Carpenter, Guy

    2015-01-01

    The spinnbarkeit of saliva reflects the ability of saliva to adhere to surfaces within the mouth, thereby serving as a protective role and aiding in lubrication. Therefore, alterations in the extensional rheology of saliva may result in the loss in adhesiveness or the ability to bind onto surfaces. Mucin glycoproteins and their structures are known to be important factors for the extensional rheological properties of saliva. The conformation of mucin depends on factors such as pH and ionic strength. Chewing is one of the main stimuli for salivary secretion but creates significant sheer stress on the salivary film which could influence mouthfeel perceptions. The current study investigates the possible factors which affect the extensional rheological properties of saliva by comparing submandibular/sublingual saliva with different oral stimuli within the same group of subjects. Unstimulated and stimulated saliva (chew, smell and taste) salivas were collected primarily from submandibular/sublingual glands. The saliva samples were measured for Spinnbarkeit followed by the measuring mucin, total protein, total calcium and bicarbonate concentrations. The results indicated correlations between rheological properties and mucin/ion concentrations. However, chewing stimulated submandibular/sublingual saliva is shown to have significantly lower Spinnbarkeit, but factors such as mucin, protein and calcium concentrations did not account for this variation. Analysis of the concentration of bicarbonate and pH appears to suggest that it has a prominent effect on extensional rheology of saliva. PMID:26305698

  8. Factors That Influence the Extensional Rheological Property of Saliva

    PubMed Central

    Vijay, Amrita; Inui, Taichi; Dodds, Michael; Proctor, Gordon; Carpenter, Guy

    2015-01-01

    The spinnbarkeit of saliva reflects the ability of saliva to adhere to surfaces within the mouth, thereby serving as a protective role and aiding in lubrication. Therefore, alterations in the extensional rheology of saliva may result in the loss in adhesiveness or the ability to bind onto surfaces. Mucin glycoproteins and their structures are known to be important factors for the extensional rheological properties of saliva. The conformation of mucin depends on factors such as pH and ionic strength. Chewing is one of the main stimuli for salivary secretion but creates significant sheer stress on the salivary film which could influence mouthfeel perceptions. The current study investigates the possible factors which affect the extensional rheological properties of saliva by comparing submandibular/sublingual saliva with different oral stimuli within the same group of subjects. Unstimulated and stimulated saliva (chew, smell and taste) salivas were collected primarily from submandibular/sublingual glands. The saliva samples were measured for Spinnbarkeit followed by the measuring mucin, total protein, total calcium and bicarbonate concentrations. The results indicated correlations between rheological properties and mucin/ion concentrations. However, chewing stimulated submandibular/sublingual saliva is shown to have significantly lower Spinnbarkeit, but factors such as mucin, protein and calcium concentrations did not account for this variation. Analysis of the concentration of bicarbonate and pH appears to suggest that it has a prominent effect on extensional rheology of saliva. PMID:26305698

  9. Factors That Influence the Extensional Rheological Property of Saliva.

    PubMed

    Vijay, Amrita; Inui, Taichi; Dodds, Michael; Proctor, Gordon; Carpenter, Guy

    2015-01-01

    The spinnbarkeit of saliva reflects the ability of saliva to adhere to surfaces within the mouth, thereby serving as a protective role and aiding in lubrication. Therefore, alterations in the extensional rheology of saliva may result in the loss in adhesiveness or the ability to bind onto surfaces. Mucin glycoproteins and their structures are known to be important factors for the extensional rheological properties of saliva. The conformation of mucin depends on factors such as pH and ionic strength. Chewing is one of the main stimuli for salivary secretion but creates significant sheer stress on the salivary film which could influence mouthfeel perceptions. The current study investigates the possible factors which affect the extensional rheological properties of saliva by comparing submandibular/sublingual saliva with different oral stimuli within the same group of subjects. Unstimulated and stimulated saliva (chew, smell and taste) salivas were collected primarily from submandibular/sublingual glands. The saliva samples were measured for Spinnbarkeit followed by the measuring mucin, total protein, total calcium and bicarbonate concentrations. The results indicated correlations between rheological properties and mucin/ion concentrations. However, chewing stimulated submandibular/sublingual saliva is shown to have significantly lower Spinnbarkeit, but factors such as mucin, protein and calcium concentrations did not account for this variation. Analysis of the concentration of bicarbonate and pH appears to suggest that it has a prominent effect on extensional rheology of saliva.

  10. Influencing factors of hydrogen bonding intensity in beer.

    PubMed

    Liu, Chunfeng; Dong, Jianjun; Yin, Xiangsheng; Li, Qi; Gu, Guoxian

    2014-11-01

    The hydrogen bonding was prone to be formed by many components in beer. Different sorts of flavor substances can affect the Chemical Shift due to their different concentrations in beer. Several key factors including 4 alcohols, 2 esters, 6 ions, 9 acids, 7 polyphenols, and 2 gravity indexes (OG and RG) were determined in this research. They could be used to investigate the relationship between hydrogen bonding intensity and the flavor components in bottled larger beers through the Correlation Analysis, Principal Component Analysis and Multiple Regression Analysis. Results showed that ethanol content was the primary influencing factor, and its correlation coefficient was 0.629 for Correlation Analysis. Some factors had a positive correlation with hydrogen bonding intensity, including the content of original gravity, ethanol, isobutanol, Cl(-), K(+), pyruvic acid, lactic acid, gallic acid, vanillic acid, and Catechin in beer. A mathematic model of hydrogen bonding Chemical Shift and the content of ethanol, pyruvic acid, K(+), and gallic acid was obtained through the Principal Component Analysis and Multiple Regression Analysis , with the adjusted R(2) being 0.779 (P = 0.001). Ethanol content was proved to be the most important factor which could impact on hydrogen bonding association in beer by Principal Component Analysis. And then, a multiple non-linearity model could be obtained as follows: [Formula: see text]. The average error was 1.23 % in the validated experiment. PMID:26396290

  11. Factors influencing inclusion of patients with malignancies in clinical trials.

    PubMed

    Tournoux, Caroline; Katsahian, Sandrine; Chevret, Sylvie; Levy, Vincent

    2006-01-15

    Participation in clinical trials remains low and is a central issue in oncology. The authors identified, through a systematic review, 75 papers published up to August 2004 that report barriers to recruitment of patients in clinical trials. These barriers range from patient preference and concern about information/consent to clinical problems with protocols. Strategies to overcome barriers on the part of patients and clinicians are needed and should be carefully evaluated. Thirty-three (44%) papers reported factors related to patients as influencing the inclusion of patients, 28 (37%) reported clinician's related factors, and 37 (49%) other factors from either specific groups of patients (30 papers, 40%) and/or other scopes (13 papers, 17%). No differences in prevalence were found between papers dedicated to hematologic malignancies and solid tumors. Factors related to clinicians as influential were more frequently reported before 1995 (70%) than thereafter (25%; P = 0.0009). Reporting specific groups of patients as influential was more frequent in North American articles (50%) than in others (14%, P = 0.008). Patients' barriers included mostly patient preference (12 papers), concern about information and/or consent (11 papers), worry about uncertainty (7 papers), and/or relationship with medical team (7 papers). Concerning clinicians, incompatibility of protocol with normal practice (nine papers), problems in complying with the protocol (eight papers), and/or consent procedure (eight papers) were the most reported factors. The remaining factors mostly relied on specific groups of patients (30 papers), notably age of patients (18 papers) and/or minority population (11 papers, all from the USA). Strategies to overcome these barriers are needed and should be carefully evaluated. PMID:16397866

  12. Biology, Genetics, and Environment: Underlying Factors Influencing Alcohol Metabolism.

    PubMed

    Wall, Tamara L; Luczak, Susan E; Hiller-Sturmhöfel, Susanne

    2016-01-01

    Gene variants encoding several of the alcohol-metabolizing enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), are among the largest genetic associations with risk for alcohol dependence. Certain genetic variants (i.e., alleles)--particularly the ADH1B*2, ADH1B*3, ADH1C*1, and ALDH2*2 alleles--have been associated with lower rates of alcohol dependence. These alleles may lead to an accumulation of acetaldehyde during alcohol metabolism, which can result in heightened subjective and objective effects. The prevalence of these alleles differs among ethnic groups; ADH1B*2 is found frequently in northeast Asians and occasionally Caucasians, ADH1B*3 is found predominantly in people of African ancestry, ADH1C*1 varies substantially across populations, and ALDH2*2 is found almost exclusively in northeast Asians. Differences in the prevalence of these alleles may account at least in part for ethnic differences in alcohol consumption and alcohol use disorder (AUD). However, these alleles do not act in isolation to influence the risk of AUD. For example, the gene effects of ALDH2*2 and ADH1B*2 seem to interact. Moreover, other factors have been found to influence the extent to which these alleles affect a person's alcohol involvement, including developmental stage, individual characteristics (e.g., ethnicity, antisocial behavior, and behavioral undercontrol), and environmental factors (e.g., culture, religion, family environment, and childhood adversity).

  13. Factors Influencing the Dysmenorrhea among Korean Adolescents in Middle School.

    PubMed

    Jeon, Ga Eul; Cha, Nam Hyun; Sok, Sohyune R

    2014-09-01

    [Purpose] This study aimed to examine the factors influencing dysmenorrhea among Korean middle school adolescents. [Subjects] The subjects included 572 female students in three different middle schools located in Seoul, South Korea. [Methods] A cross-sectional design was adopted. The measurement tools used included a demographic form and revised Menstrual distress Questionnaire (MDQ). [Results] The analyses showed that the prediction model was significant. The value of the adjusted R(2) was 0.282, which corresponds to an explanatory power of 28.2%. The factor found to have the most influence on dysmenorrhea among Korean middle school adolescents was stress, followed by health status, onset of dysmenorrhea, consecutive days of menstruation, and dietary habits. [Conclusion] Nursing intervention programs for alleviating dysmenorrhea in Korean middle school adolescents are essential in order to reduce their level of stress, improve their perceived health status, and help them to maintain regular dietary habits. Reflecting on the recent trend of female students menstruating at a younger age, public health education courses and counseling programs should offer customized methods for alleviating dysmenorrhea.

  14. A holistic model of advocacy: factors that influence its use.

    PubMed

    Kubsch, Sylvia M; Sternard, Marsha J; Hovarter, Rebecca; Matzke, Vicki

    2004-02-01

    Although advocacy is embraced by nursing as an essential component of holistic philosophy, its scope is often limited in practice. In this article, a research study that examined the use of an expanded definition of advocacy is described. A link to the role of advocacy as a complementary therapy and in relation to facilitating the use of complementary therapies by patients is provided. Fifty-two registered nurses completed a researcher developed advocacy research instrument that assessed the use of moral-ethical, legal, political, spiritual, and substitutive advocacy along with various factors thought to influence the use of advocacy including moral development, perceived assertiveness, and perceived job security. An additional 40 RN-BSN students generated case studies of advocacy enacted in practice that were used as examples of the five categories of advocacy and to support the findings of the survey. Results indicated that moral-ethical advocacy was used more often than the other four categories. Moral stage development had a significant effect on substitutive advocacy but assertiveness and job security were not significant factors influencing any category of advocacy. PMID:14744505

  15. Equilibrium and kinetic factors influencing bile sequestrant efficacy.

    PubMed

    Luner, P E; Amidon, G L

    1992-05-01

    In vitro bile salt binding equilibria and kinetic studies were performed with cholestyramine to determine how these factors influence bile sequestrant efficacy in vivo. Chloride ion at physiologic concentrations caused more than a twofold reduction in glycocholate (GCH) binding, compared to binding in the absence of salt, over a range of GCH concentrations and was also observed to displace bound GCH. In addition, chloride ion displaced from cholestyramine as a result of bile salt binding was measured using a chloride selective electrode, and the results show that bile salt binding is due to ion exchange. Comparison of the results of the equilibrium binding experiments to human data shows that the effect of anion binding competition alone cannot account for the lack of efficacy of cholestyramine. Consideration of other effects, such as additional binding competition or poor availability for binding, based on data from the literature, shows that adequate bile salt binding potential exists and that these interferences are not major factors influencing resin efficacy. In kinetic studies, both binding uptake of GCH and displacement of GCH from cholestyramine by chloride ion were relatively rapid, indicating that cholestyramine should equilibrate rapidly with bile salts in the GI tract. Based on these findings, it is suggested that the low efficacy of cholestyramine is a result mainly of its relatively poor ability to prevent bile salt reabsorption in the ileum.

  16. In-hospital resuscitation: opioids and other factors influencing survival

    PubMed Central

    Fecho, Karamarie; Jackson, Freeman; Smith, Frances; Overdyk, Frank J

    2009-01-01

    Purpose: “Code Blue” is a standard term used to alertt hospital staff that a patient requires resuscitation. This study determined rates of survival from Code Blue events and the role of opioids and other factors on survival. Methods: Data derived from medical records and the Code Blue and Pharmacy databases were analyzed for factors affecting survival. Results: During 2006, rates of survival from the code only and to discharge were 25.9% and 26.4%, respectively, for Code Blue events involving cardiopulmonary resuscitation (CPR; N = 216). Survival rates for events not ultimately requiring CPR (N = 77) were higher, with 32.5% surviving the code only and 62.3% surviving to discharge. For CPR events, rates of survival to discharge correlated inversely with time to chest compressions and defibrillation, precipitating event, need for airway management, location and age. Time of week, witnessing, postoperative status, gender and opioid use did not influence survival rates. For non-CPR events, opioid use was associated with decreased survival. Survival rates were lowest for patients receiving continuous infusions (P < 0.01) or iv boluses of opioids (P < 0.05). Conclusions: One-quarter of patients survive to discharge after a CPR Code Blue event and two-thirds survive to discharge after a non-CPR event. Opioids may influence survival from non-CPR events. PMID:20057895

  17. Identification of the influencing factors on groundwater drought in Bangladesh

    NASA Astrophysics Data System (ADS)

    Touhidul Mustafa, Syed Md.; Huysmans, Marijke

    2015-04-01

    Groundwater drought is a specific type of drought that concerns groundwater bodies. It may have a significant adverse effect on the socio-economic, agricultural, and environmental conditions. Investigating the effect of response different climatic and manmade factors on groundwater drought provides essential information for sustainable planning and management of water resources. The aim of this study is to identify the influencing factors on groundwater drought in a drought prone region in Bangladesh to understand the forcing mechanisms. The Standardised Precipitation Index (SPI) and Reconnaissance Drought Index (RDI) have been used to quantify the aggregated deficit between precipitation and the evaporative demand of the atmosphere. The influence of land use patterns on the groundwater drought has been identified by calculating spatially distributed groundwater recharge as a function of land use. The result shows that drought intensity is more severe during the dry season (November to April) compared to the rainy season (May to October). The evapotranspiration and rainfall deficit has a significant effect on meteorological drought which has a direct relation with groundwater drought. Urbanization results in a decrease of groundwater recharge which increases groundwater drought severity. Overexploitation of groundwater for irrigation and recurrent meteorological droughts are the main causes of groundwater drought in the study area. Efficient irrigation management is essential to reduce the growing pressure on groundwater resources and ensure sustainable water management. More detailed studies on climate change and land use change effects on groundwater drought are recommended. Keywords: Groundwater drought, SPI & RDI, Spatially distributed groundwater recharge, Irrigation, Bangladesh

  18. A holistic model of advocacy: factors that influence its use.

    PubMed

    Kubsch, Sylvia M; Sternard, Marsha J; Hovarter, Rebecca; Matzke, Vicki

    2004-02-01

    Although advocacy is embraced by nursing as an essential component of holistic philosophy, its scope is often limited in practice. In this article, a research study that examined the use of an expanded definition of advocacy is described. A link to the role of advocacy as a complementary therapy and in relation to facilitating the use of complementary therapies by patients is provided. Fifty-two registered nurses completed a researcher developed advocacy research instrument that assessed the use of moral-ethical, legal, political, spiritual, and substitutive advocacy along with various factors thought to influence the use of advocacy including moral development, perceived assertiveness, and perceived job security. An additional 40 RN-BSN students generated case studies of advocacy enacted in practice that were used as examples of the five categories of advocacy and to support the findings of the survey. Results indicated that moral-ethical advocacy was used more often than the other four categories. Moral stage development had a significant effect on substitutive advocacy but assertiveness and job security were not significant factors influencing any category of advocacy.

  19. Biology, Genetics, and Environment: Underlying Factors Influencing Alcohol Metabolism.

    PubMed

    Wall, Tamara L; Luczak, Susan E; Hiller-Sturmhöfel, Susanne

    2016-01-01

    Gene variants encoding several of the alcohol-metabolizing enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), are among the largest genetic associations with risk for alcohol dependence. Certain genetic variants (i.e., alleles)--particularly the ADH1B*2, ADH1B*3, ADH1C*1, and ALDH2*2 alleles--have been associated with lower rates of alcohol dependence. These alleles may lead to an accumulation of acetaldehyde during alcohol metabolism, which can result in heightened subjective and objective effects. The prevalence of these alleles differs among ethnic groups; ADH1B*2 is found frequently in northeast Asians and occasionally Caucasians, ADH1B*3 is found predominantly in people of African ancestry, ADH1C*1 varies substantially across populations, and ALDH2*2 is found almost exclusively in northeast Asians. Differences in the prevalence of these alleles may account at least in part for ethnic differences in alcohol consumption and alcohol use disorder (AUD). However, these alleles do not act in isolation to influence the risk of AUD. For example, the gene effects of ALDH2*2 and ADH1B*2 seem to interact. Moreover, other factors have been found to influence the extent to which these alleles affect a person's alcohol involvement, including developmental stage, individual characteristics (e.g., ethnicity, antisocial behavior, and behavioral undercontrol), and environmental factors (e.g., culture, religion, family environment, and childhood adversity). PMID:27163368

  20. Environmental Factors Influencing Arctic Halogen Chemistry During Late Spring

    NASA Astrophysics Data System (ADS)

    Burd, J.; Nghiem, S. V.; Simpson, W. R.

    2015-12-01

    Reactive halogen radicals (e.g. Br, Cl atoms and their oxides, BrO, ClO) are important oxidizers in the troposphere that decrease atmospheric pollutants and deplete tropospheric ozone, affecting the abundance of other oxidizers such as the hydroxyl radical. During Arctic springtime, the heterogeneous chemical cycles (often called the "bromine explosion") produce high levels of bromine monoxide (BrO), through reactions on saline snow, ice, and/or aerosol surfaces. Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) measured BrO at Barrow, AK, from 2008-2009 and 2012-2015, as well at various locations above the frozen Arctic Ocean with O-Buoys in 2008 and 2011-2015. Observed BrO levels drop suddenly during late spring (May-June) and generally do not recover, which indicates the bromine explosion cycle can no longer produce significant amounts of BrO. We have established, through an objective algorithm, the local day of year of this drop in BrO as the "seasonal end." Additionally, in about half of the years, "recurrence" events were observed where BrO levels recover for at least a day. This study investigates the environmental factors influencing seasonal end and recurrence events including: temperature, relative humidity, precipitation and snowmelt. Analysis of BrO and air temperature revealed the temperature reaches 0°C within five days of the seasonal end event; however, temperatures drop below freezing during a recurrence eve