Science.gov

Sample records for large-scale spatial variation

  1. Environmental correlates of large-scale spatial variation in the δ13C of marine animals

    NASA Astrophysics Data System (ADS)

    Barnes, Carolyn; Jennings, Jon. T. Barry, Simon

    2009-02-01

    Carbon stable isotopes can be used to trace the sources of energy supporting food chains and to estimate the contribution of different sources to a consumer's diet. However, the δ13C signature of a consumer is not sufficient to infer source without an appropriate isotopic baseline, because there is no way to determine if differences in consumer δ13C reflect source changes or baseline variation. Describing isotopic baselines is a considerable challenge when applying stable isotope techniques at large spatial scales and/or to interconnected food chains in open marine environments. One approach is to use filter-feeding consumers to integrate the high frequency and small-scale variation in the isotopic signature of phytoplankton and provide a surrogate baseline, but it can be difficult to sample a single consumer species at large spatial scales owing to rarity and/or discontinuous distribution. Here, we use the isotopic signature of a widely distributed filter-feeder (the queen scallop Aequipecten opercularis) in the north-eastern Atlantic to develop a model linking base δ13C to environmental variables. Remarkably, a single variable model based on bottom temperature has good predictive power and predicts scallop δ13C with mean error of only 0.6‰ (3%). When the model was used to predict an isotopic baseline in parts of the overall study region where scallop were not consistently sampled, the model accounted for 76% and 79% of the large-scale spatial variability (10 1-10 4 km) of the δ13C of two fish species (dab Limanda limanda and whiting Merlangus merlangius) and 44% of the δ13C variability in a mixed fish community. The results show that source studies would be significantly biased if a single baseline were applied to food webs at larger scales. Further, when baseline δ13C cannot be directly measured, a calculated baseline value can eliminate a large proportion of the unexplained variation in δ13C at higher trophic levels.

  2. Herbivory drives large-scale spatial variation in reef fish trophic interactions

    PubMed Central

    Longo, Guilherme O; Ferreira, Carlos Eduardo L; Floeter, Sergio R

    2014-01-01

    Trophic interactions play a critical role in the structure and function of ecosystems. Given the widespread loss of biodiversity due to anthropogenic activities, understanding how trophic interactions respond to natural gradients (e.g., abiotic conditions, species richness) through large-scale comparisons can provide a broader understanding of their importance in changing ecosystems and support informed conservation actions. We explored large-scale variation in reef fish trophic interactions, encompassing tropical and subtropical reefs with different abiotic conditions and trophic structure of reef fish community. Reef fish feeding pressure on the benthos was determined combining bite rates on the substrate and the individual biomass per unit of time and area, using video recordings in three sites between latitudes 17°S and 27°S on the Brazilian Coast. Total feeding pressure decreased 10-fold and the composition of functional groups and species shifted from the northern to the southernmost sites. Both patterns were driven by the decline in the feeding pressure of roving herbivores, particularly scrapers, while the feeding pressure of invertebrate feeders and omnivores remained similar. The differential contribution to the feeding pressure across trophic categories, with roving herbivores being more important in the northernmost and southeastern reefs, determined changes in the intensity and composition of fish feeding pressure on the benthos among sites. It also determined the distribution of trophic interactions across different trophic categories, altering the evenness of interactions. Feeding pressure was more evenly distributed at the southernmost than in the southeastern and northernmost sites, where it was dominated by few herbivores. Species and functional groups that performed higher feeding pressure than predicted by their biomass were identified as critical for their potential to remove benthic biomass. Fishing pressure unlikely drove the large-scale

  3. Herbivory drives large-scale spatial variation in reef fish trophic interactions.

    PubMed

    Longo, Guilherme O; Ferreira, Carlos Eduardo L; Floeter, Sergio R

    2014-12-01

    Trophic interactions play a critical role in the structure and function of ecosystems. Given the widespread loss of biodiversity due to anthropogenic activities, understanding how trophic interactions respond to natural gradients (e.g., abiotic conditions, species richness) through large-scale comparisons can provide a broader understanding of their importance in changing ecosystems and support informed conservation actions. We explored large-scale variation in reef fish trophic interactions, encompassing tropical and subtropical reefs with different abiotic conditions and trophic structure of reef fish community. Reef fish feeding pressure on the benthos was determined combining bite rates on the substrate and the individual biomass per unit of time and area, using video recordings in three sites between latitudes 17°S and 27°S on the Brazilian Coast. Total feeding pressure decreased 10-fold and the composition of functional groups and species shifted from the northern to the southernmost sites. Both patterns were driven by the decline in the feeding pressure of roving herbivores, particularly scrapers, while the feeding pressure of invertebrate feeders and omnivores remained similar. The differential contribution to the feeding pressure across trophic categories, with roving herbivores being more important in the northernmost and southeastern reefs, determined changes in the intensity and composition of fish feeding pressure on the benthos among sites. It also determined the distribution of trophic interactions across different trophic categories, altering the evenness of interactions. Feeding pressure was more evenly distributed at the southernmost than in the southeastern and northernmost sites, where it was dominated by few herbivores. Species and functional groups that performed higher feeding pressure than predicted by their biomass were identified as critical for their potential to remove benthic biomass. Fishing pressure unlikely drove the large-scale

  4. Multi-variate spatial explicit constraining of a large scale hydrological model

    NASA Astrophysics Data System (ADS)

    Rakovec, Oldrich; Kumar, Rohini; Samaniego, Luis

    2016-04-01

    model parameters leads to considerable changes in the partitioning of precipitation into runoff components, while maintaining total runoff estimates unaltered. Objective functions that take into account the spatial patters of GRACE estimates perform better than those constrained only against discharge. Improvements in parameter estimation based on multiple data sources will enhance the community efforts towards spatially consistent large scale seamless predictions. Reference: Rakovec, O., Kumar, R., Mai, J., Cuntz, M., Thober, S., Zink, M., Attinger, S., Schäfer, D., Schrön, M., Samaniego, L. (2016): Multiscale and multivariate evaluation of water fluxes and states over European river basins, J. Hydrometeorol., 17, 287-307, doi: 10.1175/JHM-D-15-0054.1.

  5. Spatial and temporal variations in rainfall over Darwin and its vicinity during different large-scale environments

    NASA Astrophysics Data System (ADS)

    Rauniyar, Surendra P.; Walsh, Kevin J. E.

    2016-02-01

    This study analyses the regional variations in rainfall over Darwin and its vicinity due to different large-scale circulations during the Australian summer by utilizing the combination of in situ and C-band polarimetric radar rainfall data at hourly resolution. The eight phases of the Madden-Julian oscillation as defined by Wheeler and Hendon (Mon Weather Rev 132(8):1917-1932, 2004) were used as indicators of different large-scale environments. The analysis found that the large-scale forcing starts to build up from phase 4 by the reversal of low- to mid-level easterly winds to moist westerly winds, reaching a maximum in phase 5 and weakening through phases 6-7. During phases 4-6, most of the study domain experiences widespread rainfall, but with distinct spatial and temporal structures. In addition, during these phases, coastal areas near Darwin receive more rainfall in the early morning (0200-0400 LT) due to the spreading or expansion of rainfall from the Beagle Gulf, explaining the occurrence of a secondary diurnal rainfall peak over Darwin. In contrast, local-scale mechanisms (sea breezes) reinvigorate from phase 8, further strengthening through phases 1-3, when low-level easterly winds become established over Darwin producing rainfall predominately over land and island locations during the afternoon. During these phases, below average rainfall is observed over most of the radar domain, except over the Tiwi Islands in phase 2.

  6. 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

  7. Large-scale spatial variation in plant δ2H and δ18O - altitude, longitude and tissue type effects

    NASA Astrophysics Data System (ADS)

    West, J. B.

    2012-12-01

    A critical component of the hydrologic cycle response to climatic variation and directional change at multiple scales is the role of vegetation. Plants modulate biological activities at short and long time scales in response to climate drivers like precipitation, including changing stomatal conductance and the spatial deployment of leaf and root biomass. Over longer time periods, species replacement and changes in dominant plant form (e.g., herbaceous versus woody) also have important effects on hydrologic pathways and the magnitudes of hydrologic fluxes along those pathways. The isotopic composition of plant tissues provides an important recorder of the dynamics of these interactions. While this is the case, important questions remain about the primary drivers of plant tissue hydrogen and oxygen isotope ratio variation and how to develop improved, realistic mechanistic models of plant tissue variation in δ2H and δ18O, thus limiting the inferences that can be drawn from isotopic variation in plant tissues. In particular, the relative strengths of climatic drivers versus physiologically-based variation remain the subject of significant debate. I report here on work designed to better understand how plants record this variation in plant tissues across relatively large spatial scales. A transect (approximately 1900 km long) was established from the Continental Divide in North America (at approximately 39° N latitude) to the Coast Range. Leaf, branch, and tree core samples of Pseudotsuga menziesii were collected across the transect. At each location along the transect, samples were collected from at least three elevations and on the western and eastern slopes of the target mountain range. Significant variation in δ2H and δ18O was observed and the relative effects of the drivers at multiple scales (within-site elevation and aspect and across the longitudinal transect) will be discussed in the context of current models of plant cellulose isotopic composition.

  8. Large-scale spatial variation in feather corticosterone in invasive house sparrows (Passer domesticus) in Mexico is related to climate.

    PubMed

    Treen, Gillian D; Hobson, Keith A; Marchant, Tracy A; Bortolotti, Gary R

    2015-09-01

    Ecologists frequently use physiological tools to understand how organisms cope with their surroundings but rarely at macroecological scales. This study describes spatial variation in corticosterone (CORT) levels in feathers of invasive house sparrows (Passer domesticus) across their range in Mexico and evaluates CORT-climate relationships with a focus on temperature and precipitation. Samples were collected from 49 sites across Mexico. Feather CORT (CORTf) was measured using methanol-based extraction and radioimmunoassay. Relationships between CORTf and spatial and climate variables were examined using simple linear regressions. Ordination was used on climate data, CORTf was plotted against the resulting axes, and univariate regression trees were used to identify important predictors of CORTf. Universal kriging interpolation was used to illustrate spatial variation in CORTf across Mexico. Correlations with ordination axes showed that high CORTf was associated with low precipitation during the rainy season and low dry season temperatures. Specifically, CORTf was negatively related to May precipitation and January and July minimum temperatures, and positively related to April deuterium excess and June minimum temperatures. CORTf was higher in second-year birds compared to after-hatch years and after-second years. House sparrows had higher CORTf levels in the hot, dry, north-central region of Mexico, and CORTf was negatively related to temperature and precipitation. House sparrows molt primarily from August-September but climate conditions throughout the year were important predictors of CORTf, suggesting that conditions outside of molt can carry over to influence energetics during feather growth. These data suggest that dry conditions are challenging for house sparrows in Mexico, supporting previous work showing that precipitation is an important predictor of broad-scale CORT variation. This work highlights the utility of CORTf for evaluating the influence of

  9. Large-scale spatial variation in feather corticosterone in invasive house sparrows (Passer domesticus) in Mexico is related to climate

    PubMed Central

    Treen, Gillian D; Hobson, Keith A; Marchant, Tracy A; Bortolotti, Gary R

    2015-01-01

    Ecologists frequently use physiological tools to understand how organisms cope with their surroundings but rarely at macroecological scales. This study describes spatial variation in corticosterone (CORT) levels in feathers of invasive house sparrows (Passer domesticus) across their range in Mexico and evaluates CORT–climate relationships with a focus on temperature and precipitation. Samples were collected from 49 sites across Mexico. Feather CORT (CORTf) was measured using methanol-based extraction and radioimmunoassay. Relationships between CORTf and spatial and climate variables were examined using simple linear regressions. Ordination was used on climate data, CORTf was plotted against the resulting axes, and univariate regression trees were used to identify important predictors of CORTf. Universal kriging interpolation was used to illustrate spatial variation in CORTf across Mexico. Correlations with ordination axes showed that high CORTf was associated with low precipitation during the rainy season and low dry season temperatures. Specifically, CORTf was negatively related to May precipitation and January and July minimum temperatures, and positively related to April deuterium excess and June minimum temperatures. CORTf was higher in second-year birds compared to after-hatch years and after-second years. House sparrows had higher CORTf levels in the hot, dry, north-central region of Mexico, and CORTf was negatively related to temperature and precipitation. House sparrows molt primarily from August–September but climate conditions throughout the year were important predictors of CORTf, suggesting that conditions outside of molt can carry over to influence energetics during feather growth. These data suggest that dry conditions are challenging for house sparrows in Mexico, supporting previous work showing that precipitation is an important predictor of broad-scale CORT variation. This work highlights the utility of CORTf for evaluating the influence of

  10. Spatial and diurnal variations of storm heights in the East Asia summer monsoon: storm height regimes and large-scale diurnal modulation

    NASA Astrophysics Data System (ADS)

    Park, Myung-Sook; Lee, Myong-In; Kim, Hyerim; Im, Jungho; Yoo, Jung-Moon

    2016-02-01

    This study investigates the spatial and diurnal variation of storm height in the East Asia summer monsoon region using 13-year Tropical Rainfall Measuring Mission Precipitation Radar data. Precipitating storms are classified as shallow (<5 km), middle (5-10 km), and deep (>10 km) depending the height. Four different regimes are identified to characterize the region: the continental (CT) shallow regime over inland China with elevated terrain, the CT deep over the Chinese Plain, the coastal (CS) middle over the East China Sea and South Sea of Korea, and the CS shallow over the south coastal area of Japan. This regime separation reflects well the distinctive regional difference in the rainfall contribution by each storm type. The occurrence frequencies of shallow, middle, and deep storms exhibit pronounced diurnal variation as well, but with significant differences in the amplitude and phase across the regimes. These lead to a diversity in the diurnal variation of surface rainfall such as bimodal morning and late evening peaks in the two CT regimes and the single morning peak in the two CS regimes. Processes involved in the diurnal variation of storms are different across the regimes, indicating difference in the contributing role of surface heating, large-scale diurnal circulation, and diurnal propagations of convective systems. The storm height also affects the rain intensity. This study highlights that the East Asia summer monsoon has distinctive sub-regional variation of the storm height distribution, thereby providing unique differences in the rainfall amount, intensity, and the diurnal variation.

  11. Large scale suppression of scalar power on a spatial condensation

    NASA Astrophysics Data System (ADS)

    Kouwn, Seyen; Kwon, O.-Kab; Oh, Phillial

    2015-03-01

    We consider a deformed single-field inflation model in terms of three SO(3) symmetric moduli fields. We find that spatially linear solutions for the moduli fields induce a phase transition during the early stage of the inflation and the suppression of scalar power spectrum at large scales. This suppression can be an origin of anomalies for large-scale perturbation modes in the cosmological observation.

  12. Spatial Variation in Foraging Behaviour of a Marine Top Predator (Phoca vitulina) Determined by a Large-Scale Satellite Tagging Program

    PubMed Central

    Sharples, Ruth J.; Moss, Simon E.; Patterson, Toby A.; Hammond, Philip S.

    2012-01-01

    The harbour seal (Phoca vitulina) is a widespread marine predator in Northern Hemisphere waters. British populations have been subject to rapid declines in recent years. Food supply or inter-specific competition may be implicated but basic ecological data are lacking and there are few studies of harbour seal foraging distribution and habits. In this study, satellite tagging conducted at the major seal haul outs around the British Isles showed both that seal movements were highly variable among individuals and that foraging strategy appears to be specialized within particular regions. We investigated whether these apparent differences could be explained by individual level factors: by modelling measures of trip duration and distance travelled as a function of size, sex and body condition. However, these were not found to be good predictors of foraging trip duration or distance, which instead was best predicted by tagging region, time of year and inter-trip duration. Therefore, we propose that local habitat conditions and the constraints they impose are the major determinants of foraging movements. Specifically the distance to profitable feeding grounds from suitable haul-out locations may dictate foraging strategy and behaviour. Accounting for proximity to productive foraging resources is likely to be an important component of understanding population processes. Despite more extensive offshore movements than expected, there was also marked fidelity to the local haul-out region with limited connectivity between study regions. These empirical observations of regional exchange at short time scales demonstrates the value of large scale electronic tagging programs for robust characterization of at-sea foraging behaviour at a wide spatial scale. PMID:22629370

  13. Controls on the large-scale spatial variations of dune field properties in the barchanoid portion of White Sands dune field, New Mexico

    NASA Astrophysics Data System (ADS)

    Pelletier, Jon D.

    2015-03-01

    Previous studies have shown that sediment fluxes and dune sizes are a maximum near the upwind margin of the White Sands dune field and decrease, to first order, with increasing distance downwind. These patterns have alternatively been attributed to a shear-stress overshoot associated with a roughness transition localized at the upwind margin and to the influence of long-wavelength topography on the hydrology and hence erodibility of dune field sediments. I point out an issue that compromises the shear-stress overshoot model and further test the hypothesis that long-wavelength topographic variations, acting in concert with feedbacks among aerodynamic, granulometric, and geomorphic variables, control dune field properties at White Sands. Building upon the existing literature, I document that the mean and variability of grain sizes, sand dryness, aerodynamic roughness lengths, bed shear stresses, sediment fluxes, and ripple and dune heights all achieve local maxima at the crests of the two most prominent scarps in the dune field, one coincident with the upwind margin and the other located 6-7 km downwind. Computational fluid dynamics (CFD) modeling predicts that bed shear stresses, erosion rates, and the supply of relatively coarse, poorly sorted sediments are localized at the two scarps due to flow line convergence, hydrology, and the spatially distributed adjustment of the boundary layer to variations in dune size. As a result, the crests of the scarps have larger ripples due to the granulometric control of ripple size. Larger grain sizes and/or larger ripples lead to larger dunes and hence larger values of bed shear stress in a positive feedback.

  14. Semantic overlay network for large-scale spatial information indexing

    NASA Astrophysics Data System (ADS)

    Zou, Zhiqiang; Wang, Yue; Cao, Kai; Qu, Tianshan; Wang, Zhongmin

    2013-08-01

    The increased demand for online services of spatial information poses new challenges to the combined filed of Computer Science and Geographic Information Science. Amongst others, these include fast indexing of spatial data in distributed networks. In this paper we propose a novel semantic overlay network for large-scale multi-dimensional spatial information indexing, called SON_LSII, which has a hybrid structure integrating a semantic quad-tree and Chord ring. The SON_LSII is a small world overlay network that achieves a very competitive trade-off between indexing efficiency and maintenance overhead. To create SON_LSII, we use an effective semantic clustering strategy that considers two aspects, i.e., the semantic of spatial information that peer holds in overlay network and physical network performances. Based on SON_LSII, a mapping method is used to reduce the multi-dimensional features into a single dimension and an efficient indexing algorithm is presented to support complex range queries of the spatial information with a massive number of concurrent users. The results from extensive experiments demonstrate that SON_LSII is superior to existing overlay networks in various respects, including scalability, maintenance, rate of indexing hits, indexing logical hops, and adaptability. Thus, the proposed SON_LSII can be used for large-scale spatial information indexing.

  15. Large-scale spatial population databases in infectious disease research

    PubMed Central

    2012-01-01

    Modelling studies on the spatial distribution and spread of infectious diseases are becoming increasingly detailed and sophisticated, with global risk mapping and epidemic modelling studies now popular. Yet, in deriving populations at risk of disease estimates, these spatial models must rely on existing global and regional datasets on population distribution, which are often based on outdated and coarse resolution data. Moreover, a variety of different methods have been used to model population distribution at large spatial scales. In this review we describe the main global gridded population datasets that are freely available for health researchers and compare their construction methods, and highlight the uncertainties inherent in these population datasets. We review their application in past studies on disease risk and dynamics, and discuss how the choice of dataset can affect results. Moreover, we highlight how the lack of contemporary, detailed and reliable data on human population distribution in low income countries is proving a barrier to obtaining accurate large-scale estimates of population at risk and constructing reliable models of disease spread, and suggest research directions required to further reduce these barriers. PMID:22433126

  16. Large-scale spatial population databases in infectious disease research.

    PubMed

    Linard, Catherine; Tatem, Andrew J

    2012-01-01

    Modelling studies on the spatial distribution and spread of infectious diseases are becoming increasingly detailed and sophisticated, with global risk mapping and epidemic modelling studies now popular. Yet, in deriving populations at risk of disease estimates, these spatial models must rely on existing global and regional datasets on population distribution, which are often based on outdated and coarse resolution data. Moreover, a variety of different methods have been used to model population distribution at large spatial scales. In this review we describe the main global gridded population datasets that are freely available for health researchers and compare their construction methods, and highlight the uncertainties inherent in these population datasets. We review their application in past studies on disease risk and dynamics, and discuss how the choice of dataset can affect results. Moreover, we highlight how the lack of contemporary, detailed and reliable data on human population distribution in low income countries is proving a barrier to obtaining accurate large-scale estimates of population at risk and constructing reliable models of disease spread, and suggest research directions required to further reduce these barriers. PMID:22433126

  17. PARTICLE ACCELERATION BY COLLISIONLESS SHOCKS CONTAINING LARGE-SCALE MAGNETIC-FIELD VARIATIONS

    SciTech Connect

    Guo, F.; Jokipii, J. R.; Kota, J. E-mail: jokipii@lpl.arizona.ed

    2010-12-10

    Diffusive shock acceleration at collisionless shocks is thought to be the source of many of the energetic particles observed in space. Large-scale spatial variations of the magnetic field have been shown to be important in understanding observations. The effects are complex, so here we consider a simple, illustrative model. Here we solve numerically the Parker transport equation for a shock in the presence of large-scale sinusoidal magnetic-field variations. We demonstrate that the familiar planar-shock results can be significantly altered as a consequence of large-scale, meandering magnetic lines of force. Because the perpendicular diffusion coefficient {kappa}{sub perpendicular} is generally much smaller than the parallel diffusion coefficient {kappa}{sub ||}, the energetic charged particles are trapped and preferentially accelerated along the shock front in the regions where the connection points of magnetic field lines intersecting the shock surface converge, and thus create the 'hot spots' of the accelerated particles. For the regions where the connection points separate from each other, the acceleration to high energies will be suppressed. Further, the particles diffuse away from the 'hot spot' regions and modify the spectra of downstream particle distribution. These features are qualitatively similar to the recent Voyager observations in the Heliosheath. These results are potentially important for particle acceleration at shocks propagating in turbulent magnetized plasmas as well as those which contain large-scale nonplanar structures. Examples include anomalous cosmic rays accelerated by the solar wind termination shock, energetic particles observed in propagating heliospheric shocks, galactic cosmic rays accelerated by supernova blast waves, etc.

  18. Large scale variation in DNA copy number in chicken breeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background Detecting genetic variation is a critical step in elucidating the molecular mechanisms underlying phenotypic diversity. Until recently, such detection has mostly focused on single nucleotide polymorphisms (SNPs) because of the ease in screening complete genomes. Another type of variant, c...

  19. Solar cycle variation of large-scale coronal structures

    NASA Technical Reports Server (NTRS)

    Antonucci, E.; Duvall, T. L.

    1974-01-01

    A green line intensity variation is associated with the interplanetary and photospheric magnetic sector structure. This effect depends on the solar cycle and occurs with the same amplitude in the latitude range 60 deg N - 60 deg S. Extended longitudinal coronal structures are suggested, which indicate the existence of closed magnetic field lines over the neutral line, separating adjacent regions of opposite polarities on the photospheric surface.

  20. Large-scale geographic variation in distribution and abundance of Australian deep-water kelp forests.

    PubMed

    Marzinelli, Ezequiel M; Williams, Stefan B; Babcock, Russell C; Barrett, Neville S; Johnson, Craig R; Jordan, Alan; Kendrick, Gary A; Pizarro, Oscar R; Smale, Dan A; Steinberg, Peter D

    2015-01-01

    Despite the significance of marine habitat-forming organisms, little is known about their large-scale distribution and abundance in deeper waters, where they are difficult to access. Such information is necessary to develop sound conservation and management strategies. Kelps are main habitat-formers in temperate reefs worldwide; however, these habitats are highly sensitive to environmental change. The kelp Ecklonia radiate is the major habitat-forming organism on subtidal reefs in temperate Australia. Here, we provide large-scale ecological data encompassing the latitudinal distribution along the continent of these kelp forests, which is a necessary first step towards quantitative inferences about the effects of climatic change and other stressors on these valuable habitats. We used the Autonomous Underwater Vehicle (AUV) facility of Australia's Integrated Marine Observing System (IMOS) to survey 157,000 m2 of seabed, of which ca 13,000 m2 were used to quantify kelp covers at multiple spatial scales (10-100 m to 100-1,000 km) and depths (15-60 m) across several regions ca 2-6° latitude apart along the East and West coast of Australia. We investigated the large-scale geographic variation in distribution and abundance of deep-water kelp (>15 m depth) and their relationships with physical variables. Kelp cover generally increased with latitude despite great variability at smaller spatial scales. Maximum depth of kelp occurrence was 40-50 m. Kelp latitudinal distribution along the continent was most strongly related to water temperature and substratum availability. This extensive survey data, coupled with ongoing AUV missions, will allow for the detection of long-term shifts in the distribution and abundance of habitat-forming kelp and the organisms they support on a continental scale, and provide information necessary for successful implementation and management of conservation reserves. PMID:25693066

  1. Large-Scale Geographic Variation in Distribution and Abundance of Australian Deep-Water Kelp Forests

    PubMed Central

    Marzinelli, Ezequiel M.; Williams, Stefan B.; Babcock, Russell C.; Barrett, Neville S.; Johnson, Craig R.; Jordan, Alan; Kendrick, Gary A.; Pizarro, Oscar R.; Smale, Dan A.; Steinberg, Peter D.

    2015-01-01

    Despite the significance of marine habitat-forming organisms, little is known about their large-scale distribution and abundance in deeper waters, where they are difficult to access. Such information is necessary to develop sound conservation and management strategies. Kelps are main habitat-formers in temperate reefs worldwide; however, these habitats are highly sensitive to environmental change. The kelp Ecklonia radiate is the major habitat-forming organism on subtidal reefs in temperate Australia. Here, we provide large-scale ecological data encompassing the latitudinal distribution along the continent of these kelp forests, which is a necessary first step towards quantitative inferences about the effects of climatic change and other stressors on these valuable habitats. We used the Autonomous Underwater Vehicle (AUV) facility of Australia’s Integrated Marine Observing System (IMOS) to survey 157,000 m2 of seabed, of which ca 13,000 m2 were used to quantify kelp covers at multiple spatial scales (10–100 m to 100–1,000 km) and depths (15–60 m) across several regions ca 2–6° latitude apart along the East and West coast of Australia. We investigated the large-scale geographic variation in distribution and abundance of deep-water kelp (>15 m depth) and their relationships with physical variables. Kelp cover generally increased with latitude despite great variability at smaller spatial scales. Maximum depth of kelp occurrence was 40–50 m. Kelp latitudinal distribution along the continent was most strongly related to water temperature and substratum availability. This extensive survey data, coupled with ongoing AUV missions, will allow for the detection of long-term shifts in the distribution and abundance of habitat-forming kelp and the organisms they support on a continental scale, and provide information necessary for successful implementation and management of conservation reserves. PMID:25693066

  2. Solar Wind and IMF Control of Large-Scale Ionospheric Currents and Their Time Variations

    NASA Astrophysics Data System (ADS)

    Juusola, L.; Kauristie, K.; Tanskanen, E.; Partamies, N.; Viljanen, A.; Andréeová, K.; van de Kamp, M.; Vanhamäki, H.; Milan, S. E.; Lester, M.; Grocott, A.; Imber, S. M.

    2014-12-01

    Patterns of high-latitude ionospheric currents are a manifestation of the solar wind-magnetosphere-ionosphere coupling. Rapid variations of the currents are associated with geomagnetically induced currents (GIC) in technological conductor systems and displays of bright, diverse auroras. One advantage of a ground-based magnetometer network over a low-orbit satellite is the possibility to distinguish between temporal and spatial variations in the data. Although ground magnetic field data can only yield distributions of ionospheric equivalent currents instead of the full horizontal and field-aligned current density, estimates for these can be obtained, under certain assumptions. We use data (1994-2013) from the ground-based IMAGE magnetometer network to derive statistical distributions of the large-scale ionospheric equivalent current density and its time-derivative as well as estimates for the field-aligned current density. These are compared with and validated against horizontal and field-aligned current density distributions obtained from low-orbit CHAMP satellite magnetic field data (2000-2010) and convection maps obtained from SuperDARN radar data (2000-2010). The ground-based distributions reveal a strong dependence of the dayside variations on radial interplanetary magnetic field (IMF) orientation and solar wind speed. The spatial distribution of enhanced nightside activity agrees with that of the average substorm bulge and depends on solar wind energy input into the magnetosphere. The most intense time variation events are related to substorm activity and occur on the nightside.

  3. Solving Large-scale Spatial Optimization Problems in Water Resources Management through Spatial Evolutionary Algorithms

    NASA Astrophysics Data System (ADS)

    Wang, J.; Cai, X.

    2007-12-01

    A water resources system can be defined as a large-scale spatial system, within which distributed ecological system interacts with the stream network and ground water system. Water resources management, the causative factors and hence the solutions to be developed have a significant spatial dimension. This motivates a modeling analysis of water resources management within a spatial analytical framework, where data is usually geo- referenced and in the form of a map. One of the important functions of Geographic information systems (GIS) is to identify spatial patterns of environmental variables. The role of spatial patterns in water resources management has been well established in the literature particularly regarding how to design better spatial patterns for satisfying the designated objectives of water resources management. Evolutionary algorithms (EA) have been demonstrated to be successful in solving complex optimization models for water resources management due to its flexibility to incorporate complex simulation models in the optimal search procedure. The idea of combining GIS and EA motivates the development and application of spatial evolutionary algorithms (SEA). SEA assimilates spatial information into EA, and even changes the representation and operators of EA. In an EA used for water resources management, the mathematical optimization model should be modified to account the spatial patterns; however, spatial patterns are usually implicit, and it is difficult to impose appropriate patterns to spatial data. Also it is difficult to express complex spatial patterns by explicit constraints included in the EA. The GIS can help identify the spatial linkages and correlations based on the spatial knowledge of the problem. These linkages are incorporated in the fitness function for the preference of the compatible vegetation distribution. Unlike a regular GA for spatial models, the SEA employs a special hierarchical hyper-population and spatial genetic operators

  4. Large-scale spatial angle measurement and the pointing error analysis

    NASA Astrophysics Data System (ADS)

    Xiao, Wen-jian; Chen, Zhi-bin; Ma, Dong-xi; Zhang, Yong; Liu, Xian-hong; Qin, Meng-ze

    2016-05-01

    A large-scale spatial angle measurement method is proposed based on inertial reference. Common measurement reference is established in inertial space, and the spatial vector coordinates of each measured axis in inertial space are measured by using autocollimation tracking and inertial measurement technology. According to the spatial coordinates of each test vector axis, the measurement of large-scale spatial angle is easily realized. The pointing error of tracking device based on the two mirrors in the measurement system is studied, and the influence of different installation errors to the pointing error is analyzed. This research can lay a foundation for error allocation, calibration and compensation for the measurement system.

  5. Optical correlator using very-large-scale integrated circuit/ferroelectric-liquid-crystal electrically addressed spatial light modulators

    NASA Technical Reports Server (NTRS)

    Turner, Richard M.; Jared, David A.; Sharp, Gary D.; Johnson, Kristina M.

    1993-01-01

    The use of 2-kHz 64 x 64 very-large-scale integrated circuit/ferroelectric-liquid-crystal electrically addressed spatial light modulators as the input and filter planes of a VanderLugt-type optical correlator is discussed. Liquid-crystal layer thickness variations that are present in the devices are analyzed, and the effects on correlator performance are investigated through computer simulations. Experimental results from the very-large-scale-integrated / ferroelectric-liquid-crystal optical-correlator system are presented and are consistent with the level of performance predicted by the simulations.

  6. Identification of large-scale genomic variation in cancer genomes using in silico reference models.

    PubMed

    Killcoyne, Sarah; Del Sol, Antonio

    2016-01-01

    Identifying large-scale structural variation in cancer genomes continues to be a challenge to researchers. Current methods rely on genome alignments based on a reference that can be a poor fit to highly variant and complex tumor genomes. To address this challenge we developed a method that uses available breakpoint information to generate models of structural variations. We use these models as references to align previously unmapped and discordant reads from a genome. By using these models to align unmapped reads, we show that our method can help to identify large-scale variations that have been previously missed. PMID:26264669

  7. Identification of large-scale genomic variation in cancer genomes using in silico reference models

    PubMed Central

    Killcoyne, Sarah; del Sol, Antonio

    2016-01-01

    Identifying large-scale structural variation in cancer genomes continues to be a challenge to researchers. Current methods rely on genome alignments based on a reference that can be a poor fit to highly variant and complex tumor genomes. To address this challenge we developed a method that uses available breakpoint information to generate models of structural variations. We use these models as references to align previously unmapped and discordant reads from a genome. By using these models to align unmapped reads, we show that our method can help to identify large-scale variations that have been previously missed. PMID:26264669

  8. Interannual drought index variations in Central Europe related to large-scale atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Beck, Christoph; Philipp, Andreas; Jacobeit, Jucundus

    2014-05-01

    This contribution investigates the relationship between large-scale atmospheric circulation and interannual variations of the standardized precipitation index (SPI) in central Europe. To this end occurrence frequencies of circulation types (CT) derived from a variety of circulation type classifications (CTC) applied to daily sea level pressure (SLP) data and mean circulation indices of vorticity (V), zonality (Z) and meridionality (M) have been utilized as predictors within multiple regression models (MRM) for the estimation of gridded 3-month SPI values over central Europe for the period 1950 to 2010. CTC based MRMs used in the analyses comprise variants concerning the basic method for CT classification, the number of CTs, the size and location of the spatial domain used for CTCs and the exclusive use of CT frequencies or the combined use of CT frequencies and mean circulation indices as predictors. Adequate MRM predictor combinations have been identified by applying stepwise multiple regression analyses within a resampling framework. The performance (robustness) of the resulting MRMs has been quantified based on a leave-one out cross-validation procedure applying several skill scores. Furthermore the relative importance of individual predictors has been estimated for each MRM. From these analyses it can be stated that i.) the consideration of vorticity characteristics within CTCs, ii.) a relatively small size of the spatial domain to which CTCs are applied and iii.) the inclusion of mean circulation indices appear to improve model skill. However model skill exhibits distinct variations between seasons and regions. Whereas promising skill can be stated for the western and northwestern parts of the central European domain only unsatisfactorily skill is reached in the more continental regions and particularly during summer. Thus it can be concluded that the here presented approaches feature the potential for the downscaling of central European drought index

  9. Analysis of large scale spatial variability of soil moisture using a geostatistical method.

    PubMed

    Lakhankar, Tarendra; Jones, Andrew S; Combs, Cynthia L; Sengupta, Manajit; Vonder Haar, Thomas H; Khanbilvardi, Reza

    2010-01-01

    Spatial and temporal soil moisture dynamics are critically needed to improve the parameterization for hydrological and meteorological modeling processes. This study evaluates the statistical spatial structure of large-scale observed and simulated estimates of soil moisture under pre- and post-precipitation event conditions. This large scale variability is a crucial in calibration and validation of large-scale satellite based data assimilation systems. Spatial analysis using geostatistical approaches was used to validate modeled soil moisture by the Agriculture Meteorological (AGRMET) model using in situ measurements of soil moisture from a state-wide environmental monitoring network (Oklahoma Mesonet). The results show that AGRMET data produces larger spatial decorrelation compared to in situ based soil moisture data. The precipitation storms drive the soil moisture spatial structures at large scale, found smaller decorrelation length after precipitation. This study also evaluates the geostatistical approach for mitigation for quality control issues within in situ soil moisture network to estimates at soil moisture at unsampled stations. PMID:22315576

  10. Small parametric model for nonlinear dynamics of large scale cyclogenesis with wind speed variations

    NASA Astrophysics Data System (ADS)

    Erokhin, Nikolay; Shkevov, Rumen; Zolnikova, Nadezhda; Mikhailovskaya, Ludmila

    2016-07-01

    It is performed a numerical investigation of a self consistent small parametric model (SPM) for large scale cyclogenesis (RLSC) by usage of connected nonlinear equations for mean wind speed and ocean surface temperature in the tropical cyclone (TC). These equations may describe the different scenario of temporal dynamics of a powerful atmospheric vortex during its full life cycle. The numerical calculations have shown that relevant choice of SPMTs incoming parameters allows to describe the seasonal behavior of regional large scale cyclogenesis dynamics for a given number of TC during the active season. It is shown that SPM allows describe also the variable wind speed variations inside the TC. Thus by usage of the nonlinear small parametric model it is possible to study the features of RLSCTs temporal dynamics during the active season in the region given and to analyze the relationship between regional cyclogenesis parameters and different external factors like the space weather including the solar activity level and cosmic rays variations.

  11. A Framework for Spatial Interaction Analysis Based on Large-Scale Mobile Phone Data

    PubMed Central

    Li, Weifeng; Cheng, Xiaoyun; Guo, Gaohua

    2014-01-01

    The overall understanding of spatial interaction and the exact knowledge of its dynamic evolution are required in the urban planning and transportation planning. This study aimed to analyze the spatial interaction based on the large-scale mobile phone data. The newly arisen mass dataset required a new methodology which was compatible with its peculiar characteristics. A three-stage framework was proposed in this paper, including data preprocessing, critical activity identification, and spatial interaction measurement. The proposed framework introduced the frequent pattern mining and measured the spatial interaction by the obtained association. A case study of three communities in Shanghai was carried out as verification of proposed method and demonstration of its practical application. The spatial interaction patterns and the representative features proved the rationality of the proposed framework. PMID:25435865

  12. Training pilots to visualize large-scale spatial relationships in a stereoscopic display

    NASA Astrophysics Data System (ADS)

    Mowafy, Lyn; Thurman, Richard A.

    1993-09-01

    In flying air intercepts, a fighter pilot must plan most tactical maneuvers well before acquiring visual contact. Success depends on one's ability to create an accurate mental model of dynamic 3D spatial relationships from 2D information displays. This paper describes an Air Force training program for visualizing large- scale dynamic spatial relationships. It employs a low-cost, portable system in which the helmet-mounted stereoscopic display reveals the unobservable spatial relationships in a virtual world. We also describe recent research which evaluated the training effectiveness of this interactive three-dimensional display technology. Three display formats have been tested for their impact on the pilot's ability to encode, retain and recall functionally relevant spatial information: (1) a set of 2D orthographic plan views, (2) a flat panel 3D perspective rendering and, (3) the 3D virtual environment. Trainees flew specified air intercepts and reviewed the flights in one of the display formats. Experts' trajectories were provided for comparison. After training, flight performance was tested on a new set of scenarios. Differences in pilots' performances under the three formats suggest how virtual environment displays can aid people learning to visualize 3D spatial relationships from 2D information.

  13. Towards Building a High Performance Spatial Query System for Large Scale Medical Imaging Data

    PubMed Central

    Aji, Ablimit; Wang, Fusheng; Saltz, Joel H.

    2013-01-01

    Support of high performance queries on large volumes of scientific spatial data is becoming increasingly important in many applications. This growth is driven by not only geospatial problems in numerous fields, but also emerging scientific applications that are increasingly data- and compute-intensive. For example, digital pathology imaging has become an emerging field during the past decade, where examination of high resolution images of human tissue specimens enables more effective diagnosis, prediction and treatment of diseases. Systematic analysis of large-scale pathology images generates tremendous amounts of spatially derived quantifications of micro-anatomic objects, such as nuclei, blood vessels, and tissue regions. Analytical pathology imaging provides high potential to support image based computer aided diagnosis. One major requirement for this is effective querying of such enormous amount of data with fast response, which is faced with two major challenges: the “big data” challenge and the high computation complexity. In this paper, we present our work towards building a high performance spatial query system for querying massive spatial data on MapReduce. Our framework takes an on demand index building approach for processing spatial queries and a partition-merge approach for building parallel spatial query pipelines, which fits nicely with the computing model of MapReduce. We demonstrate our framework on supporting multi-way spatial joins for algorithm evaluation and nearest neighbor queries for microanatomic objects. To reduce query response time, we propose cost based query optimization to mitigate the effect of data skew. Our experiments show that the framework can efficiently support complex analytical spatial queries on MapReduce. PMID:24501719

  14. Large-Scale Functional Networks Identified from Resting-State EEG Using Spatial ICA

    PubMed Central

    2016-01-01

    Several methods have been applied to EEG or MEG signals to detect functional networks. In recent works using MEG/EEG and fMRI data, temporal ICA analysis has been used to extract spatial maps of resting-state networks with or without an atlas-based parcellation of the cortex. Since the links between the fMRI signal and the electromagnetic signals are not fully established, and to avoid any bias, we examined whether EEG alone was able to derive the spatial distribution and temporal characteristics of functional networks. To do so, we propose a two-step original method: 1) An individual multi-frequency data analysis including EEG-based source localisation and spatial independent component analysis, which allowed us to characterize the resting-state networks. 2) A group-level analysis involving a hierarchical clustering procedure to identify reproducible large-scale networks across the population. Compared with large-scale resting-state networks obtained with fMRI, the proposed EEG-based analysis revealed smaller independent networks thanks to the high temporal resolution of EEG, hence hierarchical organization of networks. The comparison showed a substantial overlap between EEG and fMRI networks in motor, premotor, sensory, frontal, and parietal areas. However, there were mismatches between EEG-based and fMRI-based networks in temporal areas, presumably resulting from a poor sensitivity of fMRI in these regions or artefacts in the EEG signals. The proposed method opens the way for studying the high temporal dynamics of networks at the source level thanks to the high temporal resolution of EEG. It would then become possible to study detailed measures of the dynamics of connectivity. PMID:26785116

  15. Large-scale changes in network interactions as a physiological signature of spatial neglect

    PubMed Central

    Baldassarre, Antonello; Ramsey, Lenny; Hacker, Carl L.; Callejas, Alicia; Astafiev, Serguei V.; Metcalf, Nicholas V.; Zinn, Kristi; Rengachary, Jennifer; Snyder, Abraham Z.; Carter, Alex R.; Shulman, Gordon L.

    2014-01-01

    The relationship between spontaneous brain activity and behaviour following focal injury is not well understood. Here, we report a large-scale study of resting state functional connectivity MRI and spatial neglect following stroke in a large (n = 84) heterogeneous sample of first-ever stroke patients (within 1–2 weeks). Spatial neglect, which is typically more severe after right than left hemisphere injury, includes deficits of spatial attention and motor actions contralateral to the lesion, and low general attention due to impaired vigilance/arousal. Patients underwent structural and resting state functional MRI scans, and spatial neglect was measured using the Posner spatial cueing task, and Mesulam and Behavioural Inattention Test cancellation tests. A principal component analysis of the behavioural tests revealed a main factor accounting for 34% of variance that captured three correlated behavioural deficits: visual neglect of the contralesional visual field, visuomotor neglect of the contralesional field, and low overall performance. In an independent sample (21 healthy subjects), we defined 10 resting state networks consisting of 169 brain regions: visual-fovea and visual-periphery, sensory-motor, auditory, dorsal attention, ventral attention, language, fronto-parietal control, cingulo-opercular control, and default mode. We correlated the neglect factor score with the strength of resting state functional connectivity within and across the 10 resting state networks. All damaged brain voxels were removed from the functional connectivity:behaviour correlational analysis. We found that the correlated behavioural deficits summarized by the factor score were associated with correlated multi-network patterns of abnormal functional connectivity involving large swaths of cortex. Specifically, dorsal attention and sensory-motor networks showed: (i) reduced interhemispheric functional connectivity; (ii) reduced anti-correlation with fronto-parietal and default mode

  16. Controls on Variations of Surface Energy, Water, and Carbon Budgets within Large-Scale Amazon Basin

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Cooper, Harry J.; Grose, Andrew; Gu, Jiu-Jing; Norman, John; daRocha, Humberto R.; Dias, Pedro Silva

    2002-01-01

    A key research focus of the LBA Research Program is understanding the space-time variations in interlinked surface energy, water, and carbon budgets, the controls on these variations, and the implications of these controls on the carbon sequestering capacity of the large scale forest-pasture system that dominates the Amaz6nia landscape. Quantification of these variations and controls are investigated by a combination of in situ measurements, remotely sensed measurements from space, and a realistically forced hydrometeorological model coupled to a carbon assimilation model, capable of simulating details within the surface energy and water budgets along with the principle processes of photosynthesis and respiration. Herein we describe the results of an investigation concerning the space-time controls of carbon sources and sinks distributed over the large scale Amazon basin. The results are derived from a carbon-water-energy budget retrieval system for the large scale Amazon basin, which uses a coupled carbon assimilation-hydrometeorological model as an integrating system, forced by both in situ meteorological measurements and remotely sensed radiation and precipitation fluxes obtained from a combination of GOES, SSM/I, TOMS, and TRh4M satellite measurements. Results include validation of (a) retrieved surface radiation and precipitation fluxes based on 30-min averaged surface measurements taken at Ji-Parani in Rondania and Manaus in Amazonas, and (b) modeled sensible, latent, and C02 fluxes based on tower measurements taken at Reserva Jaru, Manaus and Fazenda Nossa Senhora. The space-time controls on carbon sequestration are partitioned into sets of factors classified by: (1) above canopy meteorology, (2) incoming surface radiation, (3) precipitation interception, and (4) indigenous stomatal processes varied over the different land covers of pristine rainforest, partially, and fully logged rainforests, and pasture lands. These are the principle meteorological

  17. Controls on Variations of Surface Energy, Water, and Carbon Budgets within Large-Scale Amazon Basin

    NASA Astrophysics Data System (ADS)

    Smith, E. A.; Cooper, H. J.; Grose, A.; Gu, J.; Norman, J.; Rocha, H. R.; Dias, P. S.

    2002-12-01

    A key research focus of the LBA Research Program is understanding the space-time variations in interlinked surface energy, water, and carbon budgets, the controls on these variations, and the implications of these controls on the carbon sequestering capacity of the large scale forest-pasture system that dominates the Amaz“nia landscape. Quantification of these variations and controls are investigated by a combination of in situ measurements, remotely sensed measurements from space, and a realistically forced hydrometeorological model coupled to a carbon assimilation model, capable of simulating details within the surface energy and water budgets along with the principle processes of photosynthesis and respiration. Herein we describe the results of an investigation concerning the space-time controls of carbon sources and sinks distributed over the large scale Amazon basin. The results are derived from a carbon-water-energy budget retrieval system for the large scale Amazon basin, which uses a coupled carbon assimilation-hydrometeorological model as an integrating system, forced by both in situ meteorological measurements and remotely sensed radiation and precipitation fluxes obtained from a combination of GOES, SSM/I, TOMS, and TRMM satellite measurements. Results include validation of (a) retrieved surface radiation and precipitation fluxes based on 30-min averaged surface measurements taken at Ji-Paran in Rond“nia and Manaus in Amazonas, and (b) modeled sensible, latent, and CO2 fluxes based on tower measurements taken at Reserva Jaru, Manaus and Fazenda Nossa Senhora. The space-time controls on carbon sequestration are partitioned into sets of factors classified by: (1) above canopy meteorology, (2) incoming surface radiation, (3) precipitation interception, and (4) indigenous stomatal processes varied over the different land covers of pristine rainforest, partially, and fully logged rainforests, and pasture lands. These are the principle meteorological

  18. SPATIALLY RESOLVED GAS KINEMATICS WITHIN A Lyα NEBULA: EVIDENCE FOR LARGE-SCALE ROTATION

    SciTech Connect

    Prescott, Moire K. M.; Martin, Crystal L.; Dey, Arjun

    2015-01-20

    We use spatially extended measurements of Lyα as well as less optically thick emission lines from an ≈80 kpc Lyα nebula at z ≈ 1.67 to assess the role of resonant scattering and to disentangle kinematic signatures from Lyα radiative transfer effects. We find that the Lyα, C IV, He II, and C III] emission lines all tell a similar story in this system, and that the kinematics are broadly consistent with large-scale rotation. First, the observed surface brightness profiles are similar in extent in all four lines, strongly favoring a picture in which the Lyα photons are produced in situ instead of being resonantly scattered from a central source. Second, we see low kinematic offsets between Lyα and the less optically thick He II line (∼100-200 km s{sup –1}), providing further support for the argument that the Lyα and other emission lines are all being produced within the spatially extended gas. Finally, the full velocity field of the system shows coherent velocity shear in all emission lines: ≈500 km s{sup –1} over the central ≈50 kpc of the nebula. The kinematic profiles are broadly consistent with large-scale rotation in a gas disk that is at least partially stable against collapse. These observations suggest that the Lyα nebula represents accreting material that is illuminated by an offset, hidden active galactic nucleus or distributed star formation, and that is undergoing rotation in a clumpy and turbulent gas disk. With an implied mass of M(

  19. Evolution of Scaling Emergence in Large-Scale Spatial Epidemic Spreading

    PubMed Central

    Wang, Lin; Li, Xiang; Zhang, Yi-Qing; Zhang, Yan; Zhang, Kan

    2011-01-01

    Background Zipf's law and Heaps' law are two representatives of the scaling concepts, which play a significant role in the study of complexity science. The coexistence of the Zipf's law and the Heaps' law motivates different understandings on the dependence between these two scalings, which has still hardly been clarified. Methodology/Principal Findings In this article, we observe an evolution process of the scalings: the Zipf's law and the Heaps' law are naturally shaped to coexist at the initial time, while the crossover comes with the emergence of their inconsistency at the larger time before reaching a stable state, where the Heaps' law still exists with the disappearance of strict Zipf's law. Such findings are illustrated with a scenario of large-scale spatial epidemic spreading, and the empirical results of pandemic disease support a universal analysis of the relation between the two laws regardless of the biological details of disease. Employing the United States domestic air transportation and demographic data to construct a metapopulation model for simulating the pandemic spread at the U.S. country level, we uncover that the broad heterogeneity of the infrastructure plays a key role in the evolution of scaling emergence. Conclusions/Significance The analyses of large-scale spatial epidemic spreading help understand the temporal evolution of scalings, indicating the coexistence of the Zipf's law and the Heaps' law depends on the collective dynamics of epidemic processes, and the heterogeneity of epidemic spread indicates the significance of performing targeted containment strategies at the early time of a pandemic disease. PMID:21747932

  20. Spatial, temporal, and hybrid decompositions for large-scale vehicle routing with time windows

    SciTech Connect

    Bent, Russell W

    2010-01-01

    This paper studies the use of decomposition techniques to quickly find high-quality solutions to large-scale vehicle routing problems with time windows. It considers an adaptive decomposition scheme which iteratively decouples a routing problem based on the current solution. Earlier work considered vehicle-based decompositions that partitions the vehicles across the subproblems. The subproblems can then be optimized independently and merged easily. This paper argues that vehicle-based decompositions, although very effective on various problem classes also have limitations. In particular, they do not accommodate temporal decompositions and may produce spatial decompositions that are not focused enough. This paper then proposes customer-based decompositions which generalize vehicle-based decouplings and allows for focused spatial and temporal decompositions. Experimental results on class R2 of the extended Solomon benchmarks demonstrates the benefits of the customer-based adaptive decomposition scheme and its spatial, temporal, and hybrid instantiations. In particular, they show that customer-based decompositions bring significant benefits over large neighborhood search in contrast to vehicle-based decompositions.

  1. Spatial dynamics of large-scale, multistage crab (Callinectes sapidus) dispersal: Determinants and consequences for recruitment

    USGS Publications Warehouse

    Etherington, L.L.; Eggleston, D.B.

    2003-01-01

    We assessed determinants and consequences of multistage dispersal on spatial recruitment of the blue crab, Callinectes sapidus, within the Croatan, Albemarle, Pamlico Estuarine System (CAPES), North Carolina, U.S.A. Large-scale sampling of early juvenile crabs over 4 years indicated that spatial abundance patterns were size-dependent and resulted from primary post-larval dispersal (pre-settlement) and secondary juvenile dispersal (early post-settlement). In general, primary dispersal led to high abundances within more seaward habitats, whereas secondary dispersal (which was relatively consistent) expanded the distribution of juveniles, potentially increasing the estuarine nursery capacity. There were strong relationships between juvenile crab density and specific wind characteristics; however, these patterns were spatially explicit. Various physical processes (e.g., seasonal wind events, timing and magnitude of tropical cyclones) interacted to influence dispersal during multiple stages and determined crab recruitment patterns. Our results suggest that the nursery value of different habitats is highly dependent on the dispersal potential (primary and secondary dispersal) to and from these areas, which is largely determined by the relative position of habitats within the estuarine landscape.

  2. Specialization of China large-scale exchange market based on constrained co-local spatial association rule

    NASA Astrophysics Data System (ADS)

    Zhang, Xuewu; Du, Yunyan; Su, Fenzhen; Wen, Wei

    2009-10-01

    With quick development of economy, spatial distribution and specialization level of China large scale commodity exchange markets whose turnover are more than 100 million Yuan, have changed greatly. And influencing factors which distribute in the research region have attribute information and spatial information and do not satisfy statistical independence. Commodity exchange market specialization index is brought forward to measure specialization degree, based on the former research and constrained co-local spatial association rule is used to analyze symbiotic pattern between specialization level and influencing factors. Constrained predicate templates and association rule templates can improve mining efficiency greatly. As the result shown, large scale commodity exchange market specialization level on country-region spatial scale went down from 2000 to 2005 and rose at 2006. The interesting association rules extracted based on defined minimum support and confident can provide officers of region governments with rational advices on large scale commodity exchange markets planning and construction.

  3. Static Analysis of Large-Scale Multibody System Using Joint Coordinates and Spatial Algebra Operator

    PubMed Central

    Omar, Mohamed A.

    2014-01-01

    Initial transient oscillations inhibited in the dynamic simulations responses of multibody systems can lead to inaccurate results, unrealistic load prediction, or simulation failure. These transients could result from incompatible initial conditions, initial constraints violation, and inadequate kinematic assembly. Performing static equilibrium analysis before the dynamic simulation can eliminate these transients and lead to stable simulation. Most exiting multibody formulations determine the static equilibrium position by minimizing the system potential energy. This paper presents a new general purpose approach for solving the static equilibrium in large-scale articulated multibody. The proposed approach introduces an energy drainage mechanism based on Baumgarte constraint stabilization approach to determine the static equilibrium position. The spatial algebra operator is used to express the kinematic and dynamic equations of the closed-loop multibody system. The proposed multibody system formulation utilizes the joint coordinates and modal elastic coordinates as the system generalized coordinates. The recursive nonlinear equations of motion are formulated using the Cartesian coordinates and the joint coordinates to form an augmented set of differential algebraic equations. Then system connectivity matrix is derived from the system topological relations and used to project the Cartesian quantities into the joint subspace leading to minimum set of differential equations. PMID:25045732

  4. Pinhole closure in spatial filters of large-scale ICF laser systems

    NASA Astrophysics Data System (ADS)

    Bikmatov, R. G.; Boley, Charles D.; Burdonsky, I. N.; Chernyak, V. M.; Fedorov, A. V.; Goltsov, A. Y.; Kondrashov, V. N.; Koptyaev, S. N.; Kovalsky, N. G.; Kuznetsov, V. N.; Milam, David; Murray, James E.; Pergament, Michael I.; Petryakov, V. M.; Smirnov, Ruslan V.; Sokolov, Victor I.; Zhuzhukalo, E. V.

    1999-07-01

    Pinhole plasma effects on parameters of the laser beam passing through the spatial filter in conditions of interest for large scale ICF laser facilities were investigated. The experiments on pinhole irradiation were conducted at power density range 1010-1011 W/cm2 with approximately 15 ns laser pulses. Al, Fe, and Ta pinholes were used. The diagnostic approach was chosen based on probing the pinhole region with frequency doubled 3-ns-long laser pulse. Ablative-plasma dynamics was studied with shadowgraphy and interferometry. Also measured were the parameters of transmitted probing beam in the near- and far-fields. The rate of pinhole 'closure' is found to decrease with the increase in the atomic number of pinhole material. The rate o pinhole closure ranges from approximately 5*106 cm/s for aluminum pinhole down to approximately 2*106 cm/s for tantalum pinhole in experiments with power density at the pinhole edge of approximately 50 GW/cm2. For aluminum and steel pinholes the parameters of the transmitted probing beam deteriorate to unacceptable level for approximately 15-20 ns after the irradiation start. In the same experimental conditions the pinholes of tantalum exhibits acceptable performance till the end of the irradiation process. Fast plasma jets converging to the pinhole axis with velocities up to approximately 107 cm/s and significantly deteriorating transmitted probing beam quality are observed. Reasonable agreement was found between the data obtained in experiments with circular pinholes and linear edge experiments.

  5. Changes in large-scale climate alter spatial synchrony of aphid pests

    NASA Astrophysics Data System (ADS)

    Sheppard, Lawrence W.; Bell, James R.; Harrington, Richard; Reuman, Daniel C.

    2016-06-01

    Spatial synchrony, the tendency of distant populations to fluctuate similarly, is a major concern in ecology. Except in special circumstances, researchers historically had difficulty identifying drivers of synchrony in field systems. Perhaps for this reason, the possibility that changes in large-scale climatic drivers may modify synchrony, thereby impacting ecosystems and human concerns, has been little examined. Here, we use wavelets to determine environmental drivers of phenological synchrony across Britain for 20 aphid species, most major crop pests. Consistently across species, changes in drivers produced large changes in aphid synchrony. Different drivers acted on different timescales: using a new wavelet analogue of the Moran theorem, we show that on long timescales (>4 years), 80% of synchrony in aphid first flights is due to synchrony in winter climate; but this explanation accounts for less short-timescale (<=4 years) synchrony. Changes in aphid synchrony over time also differed by timescale: long-timescale synchrony fell from before 1993 to after, caused by similar changes in winter climate; whereas short-timescale synchrony increased. Shifts in winter climate are attributable to the North Atlantic Oscillation, an important climatic phenomenon, so effects described here may influence other taxa. This study documents a new way that climatic changes influence populations, through altered Moran effects.

  6. Static analysis of large-scale multibody system using joint coordinates and spatial algebra operator.

    PubMed

    Omar, Mohamed A

    2014-01-01

    Initial transient oscillations inhibited in the dynamic simulations responses of multibody systems can lead to inaccurate results, unrealistic load prediction, or simulation failure. These transients could result from incompatible initial conditions, initial constraints violation, and inadequate kinematic assembly. Performing static equilibrium analysis before the dynamic simulation can eliminate these transients and lead to stable simulation. Most exiting multibody formulations determine the static equilibrium position by minimizing the system potential energy. This paper presents a new general purpose approach for solving the static equilibrium in large-scale articulated multibody. The proposed approach introduces an energy drainage mechanism based on Baumgarte constraint stabilization approach to determine the static equilibrium position. The spatial algebra operator is used to express the kinematic and dynamic equations of the closed-loop multibody system. The proposed multibody system formulation utilizes the joint coordinates and modal elastic coordinates as the system generalized coordinates. The recursive nonlinear equations of motion are formulated using the Cartesian coordinates and the joint coordinates to form an augmented set of differential algebraic equations. Then system connectivity matrix is derived from the system topological relations and used to project the Cartesian quantities into the joint subspace leading to minimum set of differential equations. PMID:25045732

  7. Spatially-Explicit Estimation of Geographical Representation in Large-Scale Species Distribution Datasets

    PubMed Central

    Kalwij, Jesse M.; Robertson, Mark P.; Ronk, Argo; Zobel, Martin; Pärtel, Meelis

    2014-01-01

    Much ecological research relies on existing multispecies distribution datasets. Such datasets, however, can vary considerably in quality, extent, resolution or taxonomic coverage. We provide a framework for a spatially-explicit evaluation of geographical representation within large-scale species distribution datasets, using the comparison of an occurrence atlas with a range atlas dataset as a working example. Specifically, we compared occurrence maps for 3773 taxa from the widely-used Atlas Florae Europaeae (AFE) with digitised range maps for 2049 taxa of the lesser-known Atlas of North European Vascular Plants. We calculated the level of agreement at a 50-km spatial resolution using average latitudinal and longitudinal species range, and area of occupancy. Agreement in species distribution was calculated and mapped using Jaccard similarity index and a reduced major axis (RMA) regression analysis of species richness between the entire atlases (5221 taxa in total) and between co-occurring species (601 taxa). We found no difference in distribution ranges or in the area of occupancy frequency distribution, indicating that atlases were sufficiently overlapping for a valid comparison. The similarity index map showed high levels of agreement for central, western, and northern Europe. The RMA regression confirmed that geographical representation of AFE was low in areas with a sparse data recording history (e.g., Russia, Belarus and the Ukraine). For co-occurring species in south-eastern Europe, however, the Atlas of North European Vascular Plants showed remarkably higher richness estimations. Geographical representation of atlas data can be much more heterogeneous than often assumed. Level of agreement between datasets can be used to evaluate geographical representation within datasets. Merging atlases into a single dataset is worthwhile in spite of methodological differences, and helps to fill gaps in our knowledge of species distribution ranges. Species distribution

  8. Design and implementation of a distributed large-scale spatial database system based on J2EE

    NASA Astrophysics Data System (ADS)

    Gong, Jianya; Chen, Nengcheng; Zhu, Xinyan; Zhang, Xia

    2003-03-01

    With the increasing maturity of distributed object technology, CORBA, .NET and EJB are universally used in traditional IT field. However, theories and practices of distributed spatial database need farther improvement in virtue of contradictions between large scale spatial data and limited network bandwidth or between transitory session and long transaction processing. Differences and trends among of CORBA, .NET and EJB are discussed in details, afterwards the concept, architecture and characteristic of distributed large-scale seamless spatial database system based on J2EE is provided, which contains GIS client application, web server, GIS application server and spatial data server. Moreover the design and implementation of components of GIS client application based on JavaBeans, the GIS engine based on servlet, the GIS Application server based on GIS enterprise JavaBeans(contains session bean and entity bean) are explained.Besides, the experiments of relation of spatial data and response time under different conditions are conducted, which proves that distributed spatial database system based on J2EE can be used to manage, distribute and share large scale spatial data on Internet. Lastly, a distributed large-scale seamless image database based on Internet is presented.

  9. Large-scale spatial distribution patterns of gastropod assemblages in rocky shores.

    PubMed

    Miloslavich, Patricia; Cruz-Motta, Juan José; Klein, Eduardo; Iken, Katrin; Weinberger, Vanessa; Konar, Brenda; Trott, Tom; Pohle, Gerhard; Bigatti, Gregorio; Benedetti-Cecchi, Lisandro; Shirayama, Yoshihisa; Mead, Angela; Palomo, Gabriela; Ortiz, Manuel; Gobin, Judith; Sardi, Adriana; Díaz, Juan Manuel; Knowlton, Ann; Wong, Melisa; Peralta, Ana C

    2013-01-01

    Gastropod assemblages from nearshore rocky habitats were studied over large spatial scales to (1) describe broad-scale patterns in assemblage composition, including patterns by feeding modes, (2) identify latitudinal pattern of biodiversity, i.e., richness and abundance of gastropods and/or regional hotspots, and (3) identify potential environmental and anthropogenic drivers of these assemblages. Gastropods were sampled from 45 sites distributed within 12 Large Marine Ecosystem regions (LME) following the NaGISA (Natural Geography in Shore Areas) standard protocol (www.nagisa.coml.org). A total of 393 gastropod taxa from 87 families were collected. Eight of these families (9.2%) appeared in four or more different LMEs. Among these, the Littorinidae was the most widely distributed (8 LMEs) followed by the Trochidae and the Columbellidae (6 LMEs). In all regions, assemblages were dominated by few species, the most diverse and abundant of which were herbivores. No latitudinal gradients were evident in relation to species richness or densities among sampling sites. Highest diversity was found in the Mediterranean and in the Gulf of Alaska, while highest densities were found at different latitudes and represented by few species within one genus (e.g. Afrolittorina in the Agulhas Current, Littorina in the Scotian Shelf, and Lacuna in the Gulf of Alaska). No significant correlation was found between species composition and environmental variables (r≤0.355, p>0.05). Contributing variables to this low correlation included invasive species, inorganic pollution, SST anomalies, and chlorophyll-a anomalies. Despite data limitations in this study which restrict conclusions in a global context, this work represents the first effort to sample gastropod biodiversity on rocky shores using a standardized protocol across a wide scale. Our results will generate more work to build global databases allowing for large-scale diversity comparisons of rocky intertidal assemblages. PMID

  10. Large-Scale Spatial Distribution Patterns of Gastropod Assemblages in Rocky Shores

    PubMed Central

    Miloslavich, Patricia; Cruz-Motta, Juan José; Klein, Eduardo; Iken, Katrin; Weinberger, Vanessa; Konar, Brenda; Trott, Tom; Pohle, Gerhard; Bigatti, Gregorio; Benedetti-Cecchi, Lisandro; Shirayama, Yoshihisa; Mead, Angela; Palomo, Gabriela; Ortiz, Manuel; Gobin, Judith; Sardi, Adriana; Díaz, Juan Manuel; Knowlton, Ann; Wong, Melisa; Peralta, Ana C.

    2013-01-01

    Gastropod assemblages from nearshore rocky habitats were studied over large spatial scales to (1) describe broad-scale patterns in assemblage composition, including patterns by feeding modes, (2) identify latitudinal pattern of biodiversity, i.e., richness and abundance of gastropods and/or regional hotspots, and (3) identify potential environmental and anthropogenic drivers of these assemblages. Gastropods were sampled from 45 sites distributed within 12 Large Marine Ecosystem regions (LME) following the NaGISA (Natural Geography in Shore Areas) standard protocol (www.nagisa.coml.org). A total of 393 gastropod taxa from 87 families were collected. Eight of these families (9.2%) appeared in four or more different LMEs. Among these, the Littorinidae was the most widely distributed (8 LMEs) followed by the Trochidae and the Columbellidae (6 LMEs). In all regions, assemblages were dominated by few species, the most diverse and abundant of which were herbivores. No latitudinal gradients were evident in relation to species richness or densities among sampling sites. Highest diversity was found in the Mediterranean and in the Gulf of Alaska, while highest densities were found at different latitudes and represented by few species within one genus (e.g. Afrolittorina in the Agulhas Current, Littorina in the Scotian Shelf, and Lacuna in the Gulf of Alaska). No significant correlation was found between species composition and environmental variables (r≤0.355, p>0.05). Contributing variables to this low correlation included invasive species, inorganic pollution, SST anomalies, and chlorophyll-a anomalies. Despite data limitations in this study which restrict conclusions in a global context, this work represents the first effort to sample gastropod biodiversity on rocky shores using a standardized protocol across a wide scale. Our results will generate more work to build global databases allowing for large-scale diversity comparisons of rocky intertidal assemblages. PMID

  11. Spatial extreme value analysis to project extremes of large-scale indicators for severe weather

    PubMed Central

    Gilleland, Eric; Brown, Barbara G; Ammann, Caspar M

    2013-01-01

    Concurrently high values of the maximum potential wind speed of updrafts (Wmax) and 0–6 km wind shear (Shear) have been found to represent conducive environments for severe weather, which subsequently provides a way to study severe weather in future climates. Here, we employ a model for the product of these variables (WmSh) from the National Center for Atmospheric Research/United States National Center for Environmental Prediction reanalysis over North America conditioned on their having extreme energy in the spatial field in order to project the predominant spatial patterns of WmSh. The approach is based on the Heffernan and Tawn conditional extreme value model. Results suggest that this technique estimates the spatial behavior of WmSh well, which allows for exploring possible changes in the patterns over time. While the model enables a method for inferring the uncertainty in the patterns, such analysis is difficult with the currently available inference approach. A variation of the method is also explored to investigate how this type of model might be used to qualitatively understand how the spatial patterns of WmSh correspond to extreme river flow events. A case study for river flows from three rivers in northwestern Tennessee is studied, and it is found that advection of WmSh from the Gulf of Mexico prevails while elsewhere, WmSh is generally very low during such extreme events. © 2013 The Authors. Environmetrics published by JohnWiley & Sons, Ltd. PMID:24223482

  12. Spatial extreme value analysis to project extremes of large-scale indicators for severe weather.

    PubMed

    Gilleland, Eric; Brown, Barbara G; Ammann, Caspar M

    2013-09-01

    Concurrently high values of the maximum potential wind speed of updrafts (W max) and 0-6 km wind shear (Shear) have been found to represent conducive environments for severe weather, which subsequently provides a way to study severe weather in future climates. Here, we employ a model for the product of these variables (WmSh) from the National Center for Atmospheric Research/United States National Center for Environmental Prediction reanalysis over North America conditioned on their having extreme energy in the spatial field in order to project the predominant spatial patterns of WmSh. The approach is based on the Heffernan and Tawn conditional extreme value model. Results suggest that this technique estimates the spatial behavior of WmSh well, which allows for exploring possible changes in the patterns over time. While the model enables a method for inferring the uncertainty in the patterns, such analysis is difficult with the currently available inference approach. A variation of the method is also explored to investigate how this type of model might be used to qualitatively understand how the spatial patterns of WmSh correspond to extreme river flow events. A case study for river flows from three rivers in northwestern Tennessee is studied, and it is found that advection of WmSh from the Gulf of Mexico prevails while elsewhere, WmSh is generally very low during such extreme events. © 2013 The Authors. Environmetrics published by JohnWiley & Sons, Ltd. PMID:24223482

  13. Annual cycle and spatial spectra of earth emitted radiation at large scales

    NASA Technical Reports Server (NTRS)

    Smith, G. L.; Bess, T. D.

    1983-01-01

    Monthly averaged, resolution enhanced global distributions of the earth's emitted radiation, as measured by the Nimbus-6 Earth Radiation Budget (ERB) wide field of view radiometers, have been analyzed for 1 year of data from July 1975 to June 1976. These distributions are expressed in terms of spherical harmonic coefficients, and time and space variability of the emitted radiation field is studied in terms of these coefficients. The average annual distribution accounts for 78 percent of the space-time power, and the annual cycle accounts for 17 percent of the power. Spatial variations over the globe are described in terms of degree variance, and longitudinal variations are described in terms of spectral power as a function of latitude. The longitudinal spectra were found to vary strongly with time.

  14. Interaction of convection and large-scale circulation with respect to MSE variations

    NASA Astrophysics Data System (ADS)

    Becker, Tobias; Stevens, Bjorn; Hohenegger, Cathy

    2015-04-01

    The ultimate drivers of convection - radiation, tropospheric humidity and surface fluxes - are altered both by the large-scale circulation and by convection itself. A quantity to which all drivers of convection contribute is moist static energy (MSE). Therefore, both a variance analysis of the MSE budget and an analysis of gross moist stability help understanding the interaction of precipitating convection with the large-scale environment. In addition, this method provides insights concerning the impact of convective aggregation on this coupling. The interaction is analyzed with a general circulation model as a starting point, but a model intercomparison study validating the general circulation model with large-eddy simulations is planned. The interaction of precipitating convection with the large-scale environment is investigated by studying the influence of surface temperature and convection scheme on the MSE variance budget in a radiative-convective equilibrium version of ECHAM6. Different fixed surface temperatures lead to different specific humidities and cause a change of longwave emission height temperature. Subsidence fraction, a large-scale property that is important for radiative transfer, increases with surface temperature, indicating an increase of convective aggregation. MSE variance increases with increasing surface temperature because more water vapor in the atmosphere allows for more MSE fluctuations. In addition, the advection term in the MSE variance budget turns from a sink to a source of MSE variance. The Tiedtke and Nordeng convection scheme show similar dependencies on surface temperature, though deep convection is forming more rapidly with the Tiedtke convection scheme. The further analysis will focus on understanding cloud-radiation and moisture-convection feedbacks within the hierarchy of models, before effective coupling parameters will be derived from cloud resolving models. These will in turn be related to assumptions used to

  15. Spatial distribution of large-scale solar magnetic fields and their relation to the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Levine, R. H.

    1979-01-01

    The spatial organization of the observed photospheric magnetic field as well as its relation to the polarity of the IMF have been studied using high resolution magnetograms from the Kitt Peak National Observatory. Systematic patterns in the large scale field are due to contributions from both concentrated flux and more diffuse flux. The polarity of the photospheric field, determined on various spatial scales, correlates with the polarity of the IMF. Analyses based on several spatial scales in the photosphere suggest that new flux in the interplanetary medium is often due to relatively small photospheric features which appear in the photosphere up to one month before they are manifest at the earth.

  16. Radial variations of large-scale magnetohydrodynamic fluctuations in the solar wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Goldstein, M. L.

    1983-01-01

    Two time periods are studied for which comprehensive data coverage is available at both 1 AU using IMP-8 and ISEE-3 and beyond using Voyager 1. One of these periods is characterized by the predominance of corotating stream interactions. Relatively small scale transient flows characterize the second period. The evolution of these flows with heliocentric distance is studied using power spectral techniques. The evolution of the transient dominated period is consistent with the hypothesis of turbulent evolution including an inverse cascade of large scales. The evolution of the corotating period is consistent with the entrainment of slow streams by faster streams in a deterministic model.

  17. Importance of Geosat orbit and tidal errors in the estimation of large-scale Indian Ocean variations

    NASA Technical Reports Server (NTRS)

    Perigaud, Claire; Zlotnicki, Victor

    1992-01-01

    To improve the estimate accuracy of large-scale meridional sea-level variations, Geosat ERM data on the Indian Ocean for a 26-month period were processed using two different techniques of orbit error reduction. The first technique removes an along-track polynomial of degree 1 over about 5000 km and the second technique removes an along-track once-per-revolution sine wave about 40,000 km. Results obtained show that the polynomial technique produces stronger attenuation of both the tidal error and the large-scale oceanic signal. After filtering, the residual difference between the two methods represents 44 percent of the total variance and 23 percent of the annual variance. The sine-wave method yields a larger estimate of annual and interannual meridional variations.

  18. Large-scale variations in observed Antarctic Sea ice extent and associated atmospheric circulation

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Parkinson, C. L.

    1981-01-01

    The 1974 Antarctic large scale sea ice extent is studied from data from Nimbus 2 and 5 and temperature and sea level pressure fields from the Australian Meteorological Data Set. Electrically Scanning Microwave Radiometer data were three-day averaged and compared with 1000 mbar atmospheric pressure and sea level pressure data, also in three-day averages. Each three-day period was subjected to a Fourier analysis and included the mean latitude of the ice extent and the phases and percent variances in terms of the first six Fourier harmonics. Centers of low pressure were found to be generally east of regions which displayed rapid ice growth, and winds acted to extend the ice equatorward. An atmospheric response was also noted as caused by the changing ice cover.

  19. Elucidating Common Structural Features of Human Pathogenic Variations Using Large-Scale Atomic-Resolution Protein Networks

    PubMed Central

    Das, Jishnu; Lee, Hao Ran; Sagar, Adithya; Fragoza, Robert; Liang, Jin; Wei, Xiaomu; Wang, Xiujuan; Mort, Matthew; Stenson, Peter D.; Cooper, David N.; Yu, Haiyuan

    2016-01-01

    With the rapid growth of structural genomics, numerous protein crystal structures have become available. However, the parallel increase in knowledge of the functional principles underlying biological processes, and more specifically the underlying molecular mechanisms of disease, has been less dramatic. This notwithstanding, the study of complex cellular networks has made possible the inference of protein functions on a large scale. Here, we combine the scale of network systems biology with the resolution of traditional structural biology to generate a large-scale atomic-resolution interactome-network comprising 3,398 interactions between 2,890 proteins with a well-defined interaction interface and interface residues for each interaction. Within the framework of this atomic-resolution network, we have explored the structural principles underlying variations causing human-inherited disease. We find that in-frame pathogenic variations are enriched at both the interface and in the interacting domain, suggesting that variations not only at interface “hot-spots,” but in the entire interacting domain can result in alterations of interactions. Further, the sites of pathogenic variations are closely related to the biophysical strength of the interactions they perturb. Finally, we show that biochemical alterations consequent to these variations are considerably more disruptive than evolutionary changes, with the most significant alterations at the protein interaction interface. PMID:24599843

  20. Relationship between North American winter temperature and large-scale atmospheric circulation anomalies and its decadal variation

    NASA Astrophysics Data System (ADS)

    Yu, B.; Lin, H.; Wu, Z. W.; Merryfield, W. J.

    2016-07-01

    The interannual relationship between North American (NA) winter temperature and large-scale atmospheric circulation anomalies and its decadal variation are analyzed. NA temperature anomalies are dominated by two leading maximum covariance analysis (MCA) modes of NA surface temperature and Northern Hemisphere 500 hPa geopotential anomalies. A new teleconnection index, termed the Asian-Bering-North American (ABNA) pattern, is constructed from the normalized geopotential field after linearly removing the contribution of the Pacific-North American (PNA) pattern. The ABNA pattern is sustained by synoptic eddy forcing. The first MCA mode of NA surface temperature is highly correlated with the PNA and ABNA teleconnections, and the second mode with the North Atlantic Oscillation (NAO). This indicates that NA temperature is largely controlled by these three large-scale atmospheric patterns, i.e., the PNA, ABNA and NAO. These temperature-circulation relationships appear stationary in the 20th century.

  1. Linking variations in large-scale climatic circulation and groundwater level in southern England

    NASA Astrophysics Data System (ADS)

    Lavers, D. A.; Hannah, D. M.; Bradley, C.

    2012-12-01

    Groundwater is a crucial water resource in many parts of the World. It can sustain river/ wetland ecosystems and human water needs during dry spells and droughts. In certain geological settings, periods of prolonged high rainfall can generate groundwater flooding while elevated water tables prime river basins for more rapid stormflow runoff. In a changing climate with projected increases in the frequency and intensity of hydrologic extremes, groundwater levels are also expected to change. In this study, we quantify the links between groundwater levels in the Lambourn river basin (a sub-catchment of the Thames basin) in southern England, which is underlain by a major permeable (Chalk) aquifer, and the large-scale climatic circulation to improve processes understanding of groundwater response to hydroclimatological drivers. Precipitation, river discharge and groundwater levels for borehole sites in the Lambourn basin over 1974-2010 are analysed as the target variables. We use two sources of monthly large-scale climate data: (1) Indices of the North Atlantic Oscillation (NAO) and the Scandinavian Pattern (SCP) from the Climate Prediction Center, and (2) gridded reanalysis data from the Twentieth Century Reanalysis Project (20CR). Firstly, links between groundwater levels (and precipitation / discharge) and the climate data are explored using monthly concurrent and lagged correlation analyses between the NAO and SCP, and groundwater (and precipitation / discharge). Secondly, gridded 20CR reanalysis data are used in a correlation analysis to determine whether the regions of strongest climate-groundwater association have more explanatory power than the static NAO/SCP indices. Results show that reasonably strong climate-groundwater connections exist in the Lambourn basin, with a several months lag; these lags are associated with the time taken for rainfall delivered to travel through the basin. The 20CR gridded product is shown to have stronger links than the NAO or SCP

  2. Tropospheric aerosols: size-differentiated chemistry and large-scale spatial distributions.

    PubMed

    Hidy, George M; Mohnen, Volker; Blanchard, Charles L

    2013-04-01

    Worldwide interest in atmospheric aerosols has emerged since the late 20th century as a part of concerns for air pollution and radiative forcing of the earth's climate. The use of aircraft and balloons for sampling and the use of remote sensing have dramatically expanded knowledge about tropospheric aerosols. Our survey gives an overview of contemporary tropospheric aerosol chemistry based mainly on in situ measurements. It focuses on fine particles less than 1-2.5 microm in diameter. The physical properties of particles by region and altitude are exemplified by particle size distributions, total number and volume concentration, and optical parameters such as extinction coefficient and aerosol optical depth. Particle chemical characterization is size dependent, differentiated by ubiquitous sulfate, and carbon, partially from anthropogenic activity. Large-scale particle distributions extend to intra- and intercontinental proportions involving plumes from population centers to natural disturbances such as dust storms and vegetation fires. In the marine environment, sea salt adds an important component to aerosols. Generally, aerosol components, most of whose sources are at the earth's surface, tend to dilute and decrease in concentration with height, but often show different (layered) profiles depending on meteorological conditions. Key microscopic processes include new particle formation aloft and cloud interactions, both cloud initiation and cloud evaporation. Measurement campaigns aloft are short term, giving snapshots of inherently transient phenomena in the troposphere. Nevertheless, these data, combined with long-term data at the surface and optical depth and transmission observations, yield a unique picture of global tropospheric particle chemistry. PMID:23687724

  3. Large-Scale Spatial Distribution Patterns of Echinoderms in Nearshore Rocky Habitats

    PubMed Central

    Iken, Katrin; Konar, Brenda; Benedetti-Cecchi, Lisandro; Cruz-Motta, Juan José; Knowlton, Ann; Pohle, Gerhard; Mead, Angela; Miloslavich, Patricia; Wong, Melisa; Trott, Thomas; Mieszkowska, Nova; Riosmena-Rodriguez, Rafael; Airoldi, Laura; Kimani, Edward; Shirayama, Yoshihisa; Fraschetti, Simonetta; Ortiz-Touzet, Manuel; Silva, Angelica

    2010-01-01

    This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1–5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cm in 1 m2 quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m−2. In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m2 quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m−2. Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by a

  4. Large-scale spatial distribution patterns of echinoderms in nearshore rocky habitats.

    PubMed

    Iken, Katrin; Konar, Brenda; Benedetti-Cecchi, Lisandro; Cruz-Motta, Juan José; Knowlton, Ann; Pohle, Gerhard; Mead, Angela; Miloslavich, Patricia; Wong, Melisa; Trott, Thomas; Mieszkowska, Nova; Riosmena-Rodriguez, Rafael; Airoldi, Laura; Kimani, Edward; Shirayama, Yoshihisa; Fraschetti, Simonetta; Ortiz-Touzet, Manuel; Silva, Angelica

    2010-01-01

    This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1-5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cm in 1 m(2) quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m(-2). In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m(2) quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m(-2). Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by

  5. Large-scale proton radiography with micrometer spatial resolution using femtosecond petawatt laser system

    NASA Astrophysics Data System (ADS)

    Wang, W. P.; Shen, B. F.; Zhang, H.; Lu, X. M.; Wang, C.; Liu, Y. Q.; Yu, L. H.; Chu, Y. X.; Li, Y. Y.; Xu, T. J.; Zhang, H.; Zhai, S. H.; Leng, Y. X.; Liang, X. Y.; Li, R. X.; Xu, Z. Z.

    2015-10-01

    An image of dragonfly with many details is obtained by the fundamental property of the high-energy proton source on a femtosecond petawatt laser system. Equal imaging of the dragonfly and high spatial resolution on the micrometer scale are simultaneously obtained. The head, wing, leg, tail, and even the internal tissue structures are clearly mapped in detail by the proton beam. Experiments show that image blurring caused by multiple Coulomb scattering can be reduced to a certain extent and the spatial resolution can be increased by attaching the dragonfly to the RCFs, which is consistent with theoretical assumptions.

  6. Large-scale proton radiography with micrometer spatial resolution using femtosecond petawatt laser system

    SciTech Connect

    Wang, W. P.; Shen, B. F. Zhang, H.; Lu, X. M.; Wang, C.; Liu, Y. Q.; Yu, L. H.; Chu, Y. X.; Li, Y. Y.; Xu, T. J.; Zhang, H.; Zhai, S. H.; Leng, Y. X.; Liang, X. Y.; Li, R. X.; Xu, Z. Z.

    2015-10-15

    An image of dragonfly with many details is obtained by the fundamental property of the high-energy proton source on a femtosecond petawatt laser system. Equal imaging of the dragonfly and high spatial resolution on the micrometer scale are simultaneously obtained. The head, wing, leg, tail, and even the internal tissue structures are clearly mapped in detail by the proton beam. Experiments show that image blurring caused by multiple Coulomb scattering can be reduced to a certain extent and the spatial resolution can be increased by attaching the dragonfly to the RCFs, which is consistent with theoretical assumptions.

  7. Spatial Knowledge of Children with Spina Bifida in a Virtual Large-Scale Space

    ERIC Educational Resources Information Center

    Wiedenbauer, Gunnar; Jansen-Osmann, Petra

    2006-01-01

    The spatial knowledge of 18 children with spina bifida and 18 healthy control children (matched according to sex, age, and verbal IQ) was investigated in a computer-simulated environment. All children had to learn a route through a virtual floor system containing 18 landmarks. Controlling for cognitive abilities, the results revealed that children…

  8. Insights into a spatially embedded social network from a large-scale snowball sample

    NASA Astrophysics Data System (ADS)

    Illenberger, J.; Kowald, M.; Axhausen, K. W.; Nagel, K.

    2011-12-01

    Much research has been conducted to obtain insights into the basic laws governing human travel behaviour. While the traditional travel survey has been for a long time the main source of travel data, recent approaches to use GPS data, mobile phone data, or the circulation of bank notes as a proxy for human travel behaviour are promising. The present study proposes a further source of such proxy-data: the social network. We collect data using an innovative snowball sampling technique to obtain details on the structure of a leisure-contacts network. We analyse the network with respect to its topology, the individuals' characteristics, and its spatial structure. We further show that a multiplication of the functions describing the spatial distribution of leisure contacts and the frequency of physical contacts results in a trip distribution that is consistent with data from the Swiss travel survey.

  9. Large-scale geographical variation in eggshell metal and calcium content in a passerine bird (Ficedula hypoleuca).

    PubMed

    Ruuskanen, Suvi; Laaksonen, Toni; Morales, Judith; Moreno, Juan; Mateo, Rafael; Belskii, Eugen; Bushuev, Andrey; Järvinen, Antero; Kerimov, Anvar; Krams, Indrikis; Morosinotto, Chiara; Mänd, Raivo; Orell, Markku; Qvarnström, Anna; Slate, Fred; Tilgar, Vallo; Visser, Marcel E; Winkel, Wolfgang; Zang, Herwig; Eeva, Tapio

    2014-03-01

    Birds have been used as bioindicators of pollution, such as toxic metals. Levels of pollutants in eggs are especially interesting, as developing birds are more sensitive to detrimental effects of pollutants than adults. Only very few studies have monitored intraspecific, large-scale variation in metal pollution across a species' breeding range. We studied large-scale geographic variation in metal levels in the eggs of a small passerine, the pied flycatcher (Ficedula hypoleuca), sampled from 15 populations across Europe. We measured 10 eggshell elements (As, Cd, Cr, Cu, Ni, Pb, Zn, Se, Sr, and Ca) and several shell characteristics (mass, thickness, porosity, and color). We found significant variation among populations in eggshell metal levels for all metals except copper. Eggshell lead, zinc, and chromium levels decreased from central Europe to the north, in line with the gradient in pollution levels over Europe, thus suggesting that eggshell can be used as an indicator of pollution levels. Eggshell lead levels were also correlated with soil lead levels and pH. Most of the metals were not correlated with eggshell characteristics, with the exception of shell mass, or with breeding success, which may suggest that birds can cope well with the current background exposure levels across Europe. PMID:24234761

  10. Methods for Modeling and Decomposing Treatment Effect Variation in Large-Scale Randomized Trials

    ERIC Educational Resources Information Center

    Ding, Peng; Feller, Avi; Miratrix, Luke

    2015-01-01

    Recent literature has underscored the critical role of treatment effect variation in estimating and understanding causal effects. This approach, however, is in contrast to much of the foundational research on causal inference. Linear models, for example, classically rely on constant treatment effect assumptions, or treatment effects defined by…

  11. An Ensemble Three-Dimensional Constrained Variational Analysis Method to Derive Large-Scale Forcing Data for Single-Column Models

    NASA Astrophysics Data System (ADS)

    Tang, Shuaiqi

    Atmospheric vertical velocities and advective tendencies are essential as large-scale forcing data to drive single-column models (SCM), cloud-resolving models (CRM) and large-eddy simulations (LES). They cannot be directly measured or easily calculated with great accuracy from field measurements. In the Atmospheric Radiation Measurement (ARM) program, a constrained variational algorithm (1DCVA) has been used to derive large-scale forcing data over a sounding network domain with the aid of flux measurements at the surface and top of the atmosphere (TOA). We extend the 1DCVA algorithm into three dimensions (3DCVA) along with other improvements to calculate gridded large-scale forcing data. We also introduce an ensemble framework using different background data, error covariance matrices and constraint variables to quantify the uncertainties of the large-scale forcing data. The results of sensitivity study show that the derived forcing data and SCM simulated clouds are more sensitive to the background data than to the error covariance matrices and constraint variables, while horizontal moisture advection has relatively large sensitivities to the precipitation, the dominate constraint variable. Using a mid-latitude cyclone case study in March 3rd, 2000 at the ARM Southern Great Plains (SGP) site, we investigate the spatial distribution of diabatic heating sources (Q1) and moisture sinks (Q2), and show that they are consistent with the satellite clouds and intuitive structure of the mid-latitude cyclone. We also evaluate the Q1 and Q2 in analysis/reanalysis, finding that the regional analysis/reanalysis all tend to underestimate the sub-grid scale upward transport of moist static energy in the lower troposphere. With the uncertainties from large-scale forcing data and observation specified, we compare SCM results and observations and find that models have large biases on cloud properties which could not be fully explained by the uncertainty from the large-scale forcing

  12. Characterisation of the large-scale production process of oyster mushroom (Pleurotus ostreatus) with the analysis of succession and spatial heterogeneity of lignocellulolytic enzyme activities.

    PubMed

    Bánfi, Renáta; Pohner, Zsuzsanna; Kovács, József; Luzics, Szabina; Nagy, Adrienn; Dudás, Melinda; Tanos, Péter; Márialigeti, Károly; Vajna, Balázs

    2015-12-01

    Oyster mushroom (Pleurotus ostreatus) lignocellulolytic enzyme activity pattern and variation was investigated in a large-scale facility from spawning until the end of the second flush. In the first cultivation cycle laccase production reached its peak during vegetative growth stage, while manganese-peroxidase showed the highest activity during fruiting body induction. Cellulose and hemicellulose degrading enzymes had maximal activity at the beginning of flush and harvest stage. The enzyme activities showed similar tendencies among five different mushroom substrate blocks representing a production house. The spatial variability analysis of enzyme activities pointed out the within substrate block heterogeneity as the main source if variation. This result was confirmed by Combined Cluster and Discriminant Analysis (CCDA) method showing minimal among block heterogeneity considering the whole investigation period; furthermore in the first cultivation cycle all blocks were grouped into one cluster. PMID:26615756

  13. Using large-scale genome variation cohorts to decipher the molecular mechanism of cancer.

    PubMed

    Habermann, Nina; Mardin, Balca R; Yakneen, Sergei; Korbel, Jan O

    2016-01-01

    Characterizing genomic structural variations (SVs) in the human genome remains challenging, and there is a growing interest to understand somatic SVs occurring in cancer, a disease of the genome. A havoc-causing SV process known as chromothripsis scars the genome when localized chromosome shattering and repair occur in a one-off catastrophe. Recent efforts led to the development of a set of conceptual criteria for the inference of chromothripsis events in cancer genomes and to the development of experimental model systems for studying this striking DNA alteration process in vitro. We discuss these approaches, and additionally touch upon current "Big Data" efforts that employ hybrid cloud computing to enable studies of numerous cancer genomes in an effort to search for commonalities and differences in molecular DNA alteration processes in cancer. PMID:27342254

  14. Large-Scale Survey of Intraspecific Fitness and Cell Morphology Variation in a Protoploid Yeast Species

    PubMed Central

    Jung, Paul P.; Sigwalt, Anastasie; Ohnuki, Shinsuke; de Montigny, Jacky; Ohya, Yoshikazu; Schacherer, Joseph

    2016-01-01

    It is now clear that the exploration of the genetic and phenotypic diversity of nonmodel species greatly improves our knowledge in biology. In this context, we recently launched a population genomic analysis of the protoploid yeast Lachancea kluyveri (formerly Saccharomyces kluyveri), highlighting a broad genetic diversity (π = 17 × 10−3) compared to the yeast model organism, S. cerevisiae (π = 4 × 10−3). Here, we sought to generate a comprehensive view of the phenotypic diversity in this species. In total, 27 natural L. kluyveri isolates were subjected to trait profiling using the following independent approaches: (i) analyzing growth in 55 growth conditions and (ii) investigating 501 morphological changes at the cellular level. Despite higher genetic diversity, the fitness variance observed in L. kluyveri is lower than that in S. cerevisiae. However, morphological features show an opposite trend. In addition, there is no correlation between the origins (ecological or geographical) of the isolate and the phenotypic patterns, demonstrating that trait variation follows neither population history nor source environment in L. kluyveri. Finally, pairwise comparisons between growth rate correlation and genetic diversity show a clear decrease in phenotypic variability linked to genome variation increase, whereas no such a trend was identified for morphological changes. Overall, this study reveals for the first time the phenotypic diversity of a distantly related species to S. cerevisiae. Given its genetic properties, L. kluyveri might be useful in further linkage mapping analyses of complex traits, and could ultimately provide a better insight into the evolution of the genotype–phenotype relationship across yeast species. PMID:26888866

  15. Large-scale causes of variation in the serpentine vegetation of California

    USGS Publications Warehouse

    Grace, J.B.; Safford, H.D.; Harrison, S.

    2007-01-01

    Serpentine vegetation in California ranges from forest to shrubland and grassland, harbors many rare and endemic species, and is only moderately altered by invasive exotic species at the present time. To better understand the factors regulating the distribution of common/representative species, endemic/rare species, and the threat of exotics in this important flora, we analyzed broad-scale community patterns and environmental conditions in a geographically stratified set of samples from across the state. We considered three major classes of environmental influences: climate (especially precipitation), soils (especially the Mg2+/Ca2+ ratio), and the indirect influences of climate on soils. We used ordination to identify the major axes of variation in common species abundances, structural equation models to analyze the relationship of community axes and endemic and exotic species richness to the environment, and group analysis techniques to identify consistent groupings of species and characterize their properties. We found that community variation could be explained by a two-axis ordination. One axis ranged from conifer forest to grassland and was strongly related to precipitation. The second axis ranged from chaparral to grassland and had little relationship to current environmental conditions, suggesting a possible role for successional history. Precipitation and elevation were respectively the largest influences on endemic and exotic richness, followed by Mg 2+/Ca2+. The results also support the idea that long-term precipitation patterns have altered the Mg2+/Ca2+ ratio via selective leaching, resulting in indirect influences on endemics (positive) and exotics (negative) but not affecting the abundances of common species. We discuss implications of these findings for the conservation of the California serpentine flora. ?? 2007 Springer Science+Business Media B.V.

  16. Spatially Resolved Spectroscopy of Europa: The Distinct Spectrum of Large-scale Chaos

    NASA Astrophysics Data System (ADS)

    Fischer, P. D.; Brown, M. E.; Hand, K. P.

    2015-11-01

    We present a comprehensive analysis of spatially resolved moderate spectral resolution near-infrared spectra obtained with the adaptive optics system at the Keck Observatory. We identify three compositionally distinct end member regions: the trailing hemisphere bullseye, the leading hemisphere upper latitudes, and a third component associated with leading hemisphere chaos units. We interpret the composition of the three end member regions to be dominated by irradiation products, water ice, and evaporite deposits or salt brines, respectively. The third component is associated with geological features and distinct from the geography of irradiation, suggesting an endogenous identity. Identifying the endogenous composition is of particular interest for revealing the subsurface composition. However, its spectrum is not consistent with linear mixtures of the salt minerals previously considered relevant to Europa. The spectrum of this component is distinguished by distorted hydration features rather than distinct spectral features, indicating hydrated minerals but making unique identification difficult. In particular, it lacks features common to hydrated sulfate minerals, challenging the traditional view of an endogenous salty component dominated by Mg-sulfates. Chloride evaporite deposits are one possible alternative.

  17. Large-scale spatial and temporal genetic diversity of feline calicivirus.

    PubMed

    Coyne, Karen P; Christley, Rob M; Pybus, Oliver G; Dawson, Susan; Gaskell, Rosalind M; Radford, Alan D

    2012-10-01

    Feline calicivirus (FCV) is an important pathogen of domestic cats and a frequently used model of human caliciviruses. Here we use an epidemiologically rigorous sampling framework to describe for the first time the phylodynamics of a calicivirus at regional and national scales. A large number of FCV strains cocirculated in the United Kingdom at the national and community levels, with no strain comprising more than 5% and 14% of these populations, respectively. The majority of strains exhibited a relatively restricted geographical range, with only two strains (one field virus and one vaccine virus) spreading further than 100 km. None of the field strains were identified outside the United Kingdom. Temporally, while some strains persisted locally for the majority of the study, others may have become locally extinct. Evolutionary analysis revealed a radial phylogeny with little bootstrap support for nodes above the strain level. In most cases, spatially and temporally diverse strains intermingled in the phylogeny. Together, these data suggest that current FCV evolution is not associated with selective competition among strains. Rather, the genetic and antigenic landscape in each geographical location is highly complex, with many strains cocirculating. These variants likely exist at the community level by a combination of de novo evolution and occasional gene flow from the wider national population. This complexity provides a benchmark, for the first time, against which vaccine cross-protection at both local and national levels can be judged. PMID:22855496

  18. Large-scale variation in boreal and temperate forest carbon turnover rate related to climate

    NASA Astrophysics Data System (ADS)

    Thurner, Martin; Beer, Christian; Carvalhais, Nuno; Forkel, Matthias; Santoro, Maurizio; Tum, Markus; Schmullius, Christiane

    2016-05-01

    Vegetation carbon turnover processes in forest ecosystems and their dominant drivers are far from being understood at a broader scale. Many of these turnover processes act on long timescales and include a lateral dimension and thus can hardly be investigated by plot-level studies alone. Making use of remote sensing-based products of net primary production (NPP) and biomass, here we show that spatial gradients of carbon turnover rate (k) in Northern Hemisphere boreal and temperate forests are explained by different climate-related processes depending on the ecosystem. k is related to frost damage effects and the trade-off between growth and frost adaptation in boreal forests, while drought stress and climate effects on insects and pathogens can explain an elevated k in temperate forests. By identifying relevant processes underlying broadscale patterns in k, we provide the basis for a detailed exploration of these mechanisms in field studies, and ultimately the improvement of their representations in global vegetation models (GVMs).

  19. Robust classification of protein variation using structural modelling and large-scale data integration

    PubMed Central

    Baugh, Evan H.; Simmons-Edler, Riley; Müller, Christian L.; Alford, Rebecca F.; Volfovsky, Natalia; Lash, Alex E.; Bonneau, Richard

    2016-01-01

    Existing methods for interpreting protein variation focus on annotating mutation pathogenicity rather than detailed interpretation of variant deleteriousness and frequently use only sequence-based or structure-based information. We present VIPUR, a computational framework that seamlessly integrates sequence analysis and structural modelling (using the Rosetta protein modelling suite) to identify and interpret deleterious protein variants. To train VIPUR, we collected 9477 protein variants with known effects on protein function from multiple organisms and curated structural models for each variant from crystal structures and homology models. VIPUR can be applied to mutations in any organism's proteome with improved generalized accuracy (AUROC .83) and interpretability (AUPR .87) compared to other methods. We demonstrate that VIPUR's predictions of deleteriousness match the biological phenotypes in ClinVar and provide a clear ranking of prediction confidence. We use VIPUR to interpret known mutations associated with inflammation and diabetes, demonstrating the structural diversity of disrupted functional sites and improved interpretation of mutations associated with human diseases. Lastly, we demonstrate VIPUR's ability to highlight candidate variants associated with human diseases by applying VIPUR to de novo variants associated with autism spectrum disorders. PMID:26926108

  20. Robust classification of protein variation using structural modelling and large-scale data integration.

    PubMed

    Baugh, Evan H; Simmons-Edler, Riley; Müller, Christian L; Alford, Rebecca F; Volfovsky, Natalia; Lash, Alex E; Bonneau, Richard

    2016-04-01

    Existing methods for interpreting protein variation focus on annotating mutation pathogenicity rather than detailed interpretation of variant deleteriousness and frequently use only sequence-based or structure-based information. We present VIPUR, a computational framework that seamlessly integrates sequence analysis and structural modelling (using the Rosetta protein modelling suite) to identify and interpret deleterious protein variants. To train VIPUR, we collected 9477 protein variants with known effects on protein function from multiple organisms and curated structural models for each variant from crystal structures and homology models. VIPUR can be applied to mutations in any organism's proteome with improved generalized accuracy (AUROC .83) and interpretability (AUPR .87) compared to other methods. We demonstrate that VIPUR's predictions of deleteriousness match the biological phenotypes in ClinVar and provide a clear ranking of prediction confidence. We use VIPUR to interpret known mutations associated with inflammation and diabetes, demonstrating the structural diversity of disrupted functional sites and improved interpretation of mutations associated with human diseases. Lastly, we demonstrate VIPUR's ability to highlight candidate variants associated with human diseases by applying VIPUR tode novovariants associated with autism spectrum disorders. PMID:26926108

  1. Large-scale variation in lithospheric structure along and across the Kenya rift

    USGS Publications Warehouse

    Prodehl, C.; Mechie, J.; Kaminski, W.; Fuchs, K.; Grosse, C.; Hoffmann, H.; Stangl, R.; Stellrecht, R.; Khan, M.A.; Maguire, Peter K.H.; Kirk, W.; Keller, Gordon R.; Githui, A.; Baker, M.; Mooney, W.; Criley, E.; Luetgert, J.; Jacob, B.; Thybo, H.; Demartin, M.; Scarascia, S.; Hirn, A.; Bowman, J.R.; Nyambok, I.; Gaciri, S.; Patel, J.; Dindi, E.; Griffiths, D.H.; King, R.F.; Mussett, A.E.; Braile, L.W.; Thompson, G.; Olsen, K.; Harder, S.; Vees, R.; Gajewski, D.; Schulte, A.; Obel, J.; Mwango, F.; Mukinya, J.; Riaroh, D.

    1991-01-01

    The Kenya rift is one of the classic examples of a continental rift zone: models for its evolution range from extension of the lithosphere by pure shear1, through extension by simple shear2, to diapiric upwelling of an asthenolith3. Following a pilot study in 19854, the present work involved the shooting of three seismic refraction and wide-angle reflection profiles along the axis, across the margins, and on the northeastern flank of the rift (Fig. 1). These lines were intended to reconcile the different crustal thickness estimates for the northern and southern parts of the rift4-6 and to reveal the structure across the rift, including that beneath the flanks. The data, presented here, reveal significant lateral variations in structure both along and across the rift. The crust thins along the rift axis from 35 km in the south to 20 km in the north; there are abrupt changes in Mono depth and uppermost-mantle seismic velocity across the rift margins, and crustal thickening across the boundary between the Archaean craton and PanAfrican orogenic belt immediately west of the rift. These results suggest that thickened crust may have controlled the rift's location, that there is a decrease in extension from north to south, and that the upper mantle immediately beneath the rift may contain reservoirs of magma generated at greater depth.

  2. Large-scale spatial patterns in estuaries: estuarine macrobenthic communities in the Schelde estuary, NW Europe

    NASA Astrophysics Data System (ADS)

    Ysebaert, T.; Herman, P. M. J.; Meire, P.; Craeymeersch, J.; Verbeek, H.; Heip, C. H. R.

    2003-05-01

    the two other main gradients. The different assemblages are further described in terms of indicator species and abiotic characteristics. The results showed that at a large, estuarine scale a considerable fraction of the variation in abundance and biomass of the benthic macrofauna correlated very well with environmental factors (depth, salinity, tidal current velocity, sediment composition).

  3. Large-scale sea level, thermocline, and wind variations in the Indonesian throughflow region

    NASA Astrophysics Data System (ADS)

    Bray, Nancy A.; Hautala, Susan; Chong, Jackson; Pariwono, John

    1996-05-01

    The Indonesian throughflow is presumed to be driven by a sea level gradient from the Pacific to the Indian Ocean. Deep throughflow transport may also be driven by a steric gradient between the two basins. The sea level gradient, in turn, is thought to be maintained by the differing wind patterns in the two basins: monsoonal in the Indian Ocean and trades in the western equatorial Pacific. In the interaction between sea level, wind stress, and thermocline depth as identified from historical measurements, we find (1) over the Indian, Indonesian, and equatorial Pacific basins and specifically within the throughflow region, sea level, and thermocline seasonal variations are negatively correlated (sea level rise corresponding to thermocline deepening) and sea level and meridional wind stress are also correlated; (2) the expected strong seasonal gradients in sea level through the eastern throughflow region (near the island of Timor) are found, though without an accompanying thermocline depth gradient; (3) seasonal convergence in baroclinic, upper ocean throughflow transport previously identified [Meyers et al., 1995] in the Timor Sea is associated with changes in sea level as well as upper ocean dynamic height at annual period but not at semiannual; (4) interannual variability explains more of the sea level variance in the eastern throughflow region than is explained by seasonal harmonics; however, there does not appear to be a strong interannual signal in the sea level gradient to drive fluctuations in the upper ocean throughflow. We hypothesize that seasonal variability in the upper layer throughflow and interannual variability in the deep throughflow are the predominant results of the complex interaction of forcing mechanisms.

  4. Developing a 3D Constrained Variational Analysis Method to Calculate Large Scale Forcing Data and the Applications

    NASA Astrophysics Data System (ADS)

    Tang, S.; Zhang, M. H.

    2014-12-01

    Large-scale forcing data (vertical velocities and advective tendencies) are important atmospheric fields to drive single-column models (SCM), cloud-resolving models (CRM) and large-eddy simulations (LES), but they are difficult to calculate accurately. The current 1-dimensional constrained variational analysis (1D CVA) method (Zhang and Lin, 1997) used by the Atmospheric Radiation Measurement (ARM) program is limited to represent the average of a sounding network domain. We extended the original 1D CVA algorithm into 3-dimensional along with other improvements, calculated gridded large-scale forcing data, apparent heating sources (Q1) and moisture sinks (Q2), and compared with 5 reanalyses: ERA-Interim, NCEP CFSR, MERRA, JRA55 and NARR for a mid-latitude spring cyclone case. The results from a case study for in March 3rd 2000 at the Southern Great Plain (SGP) show that reanalyses generally captured the structure of the mid-latitude cyclone, but they have serious biases in the 2nd order derivative terms (divergences and horizontal derivations) at regional scales of less than a few hundred kilometers. Our algorithm provides a set of atmospheric fields consistent with the observed constraint variables at the surface and top of the atmosphere better than reanalyses. The analyzed atmospheric fields can be used in SCM, CRM and LES to provide 3-dimensional dynamical forcing, or be used to evaluate reanalyses or model simulations.

  5. Curbing variations in packaging process through Six Sigma way in a large-scale food-processing industry

    NASA Astrophysics Data System (ADS)

    Desai, Darshak A.; Kotadiya, Parth; Makwana, Nikheel; Patel, Sonalinkumar

    2015-08-01

    Indian industries need overall operational excellence for sustainable profitability and growth in the present age of global competitiveness. Among different quality and productivity improvement techniques, Six Sigma has emerged as one of the most effective breakthrough improvement strategies. Though Indian industries are exploring this improvement methodology to their advantage and reaping the benefits, not much has been presented and published regarding experience of Six Sigma in the food-processing industries. This paper is an effort to exemplify the application of Six Sigma quality improvement drive to one of the large-scale food-processing sectors in India. The paper discusses the phase wiz implementation of define, measure, analyze, improve, and control (DMAIC) on one of the chronic problems, variations in the weight of milk powder pouch. The paper wraps up with the improvements achieved and projected bottom-line gain to the unit by application of Six Sigma methodology.

  6. A large scale experimental approach to the measurement of spatially and temporally localised loading from the detonation of shallow-buried explosives

    NASA Astrophysics Data System (ADS)

    Clarke, S. D.; Fay, S. D.; Warren, J. A.; Tyas, A.; Rigby, S. E.; Elgy, I.

    2015-01-01

    A large scale experimental approach to the direct measurement of the spatial and temporal variation in loading resulting from an explosive event has been developed. The approach utilises a fixed target plate through which Hopkinson pressure bars are inserted. This technique allows the pressure-time histories for an array of bars to be generated, giving data over a large area of interest. A numerical interpolation technique has also been developed to allow for the full pressure-time history for any point on the target plate to be estimated and hence total imparted impulse to be calculated. The principles underlying the design of the experimental equipment are discussed, along with the importance of carefully controlling the explosive preparation, and the method and location of the detonation initiation. Initial results showing the key features of the loading recorded and the consistency attainable by this method are presented along with the data interpolation routines used to estimate the loading on the entire face.

  7. Coalescent-based method for learning parameters of admixture events from large-scale genetic variation data.

    PubMed

    Tsai, Ming-Chi; Blelloch, Guy; Ravi, R; Schwartz, Russell

    2013-01-01

    Detecting and quantifying the timing and the genetic contributions of parental populations to a hybrid population is an important but challenging problem in reconstructing evolutionary histories from genetic variation data. With the advent of high throughput genotyping technologies, new methods suitable for large-scale data are especially needed. Furthermore, existing methods typically assume the assignment of individuals into subpopulations is known, when that itself is a difficult problem often unresolved for real data. Here, we propose a novel method that combines prior work for inferring non reticulate population structures with an MCMC scheme for sampling over admixture scenarios to both identify population assignments and learn divergence times and admixture proportions for those populations using genome-scale admixed genetic variation data. We validated our method using coalescent simulations and a collection of real bovine and human variation data. On simulated sequences, our methods show better accuracy and faster run time than leading competitive methods in estimating admixture fractions and divergence times. Analysis on the real data further shows our methods to be effective at matching our best current knowledge about the relevant populations. PMID:23959633

  8. Spatial Fingerprints of Community Structure in Human Interaction Network for an Extensive Set of Large-Scale Regions

    PubMed Central

    Kallus, Zsófia; Barankai, Norbert; Szüle, János; Vattay, Gábor

    2015-01-01

    Human interaction networks inferred from country-wide telephone activity recordings were recently used to redraw political maps by projecting their topological partitions into geographical space. The results showed remarkable spatial cohesiveness of the network communities and a significant overlap between the redrawn and the administrative borders. Here we present a similar analysis based on one of the most popular online social networks represented by the ties between more than 5.8 million of its geo-located users. The worldwide coverage of their measured activity allowed us to analyze the large-scale regional subgraphs of entire continents and an extensive set of examples for single countries. We present results for North and South America, Europe and Asia. In our analysis we used the well-established method of modularity clustering after an aggregation of the individual links into a weighted graph connecting equal-area geographical pixels. Our results show fingerprints of both of the opposing forces of dividing local conflicts and of uniting cross-cultural trends of globalization. PMID:25993329

  9. Spatial fingerprints of community structure in human interaction network for an extensive set of large-scale regions.

    PubMed

    Kallus, Zsófia; Barankai, Norbert; Szüle, János; Vattay, Gábor

    2015-01-01

    Human interaction networks inferred from country-wide telephone activity recordings were recently used to redraw political maps by projecting their topological partitions into geographical space. The results showed remarkable spatial cohesiveness of the network communities and a significant overlap between the redrawn and the administrative borders. Here we present a similar analysis based on one of the most popular online social networks represented by the ties between more than 5.8 million of its geo-located users. The worldwide coverage of their measured activity allowed us to analyze the large-scale regional subgraphs of entire continents and an extensive set of examples for single countries. We present results for North and South America, Europe and Asia. In our analysis we used the well-established method of modularity clustering after an aggregation of the individual links into a weighted graph connecting equal-area geographical pixels. Our results show fingerprints of both of the opposing forces of dividing local conflicts and of uniting cross-cultural trends of globalization. PMID:25993329

  10. Rainfall hotspots over the southern tropical Andes: Spatial distribution, rainfall intensity, and relations with large-scale atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Espinoza, Jhan Carlo; Chavez, Steven; Ronchail, Josyane; Junquas, Clémentine; Takahashi, Ken; Lavado, Waldo

    2015-05-01

    The Andes/Amazon transition is among the rainiest regions of the world and the interactions between large-scale circulation and the topography that determine its complex rainfall distribution remain poorly known. This work provides an in-depth analysis of the spatial distribution, variability, and intensity of rainfall in the southern Andes/Amazon transition, at seasonal and intraseasonal time scales. The analysis is based on comprehensive daily rainfall data sets from meteorological stations in Peru and Bolivia. We compare our results with high-resolution rainfall TRMM-PR 2A25 estimations. Hotspot regions are identified at low elevations in the Andean foothills (400-700 masl) and in windward conditions at Quincemil and Chipiriri, where more than 4000 mm rainfall per year are recorded. Orographic effects and exposure to easterly winds produce a strong annual rainfall gradient between the lowlands and the Andes that can reach 190 mm/km. Although TRMM-PR reproduces the spatial distribution satisfactorily, it underestimates rainfall by 35% in the hotspot regions. In the Peruvian hotspot, exceptional rainfall occurs during the austral dry season (around 1000 mm in June-July-August; JJA), but not in the Bolivian hotspot. The direction of the low-level winds over the Andean foothills partly explains this difference in the seasonal rainfall cycle. At intraseasonal scales in JJA, we found that, during northerly wind regimes, positive rainfall anomalies predominate over the lowland and the eastern flank of the Andes, whereas less rain falls at higher altitudes. On the other hand, during southerly regimes, rainfall anomalies are negative in the hotspot regions. The influence of cross-equatorial winds is particularly clear below 2000 masl.

  11. Global direct pressures on biodiversity by large-scale metal mining: Spatial distribution and implications for conservation.

    PubMed

    Murguía, Diego I; Bringezu, Stefan; Schaldach, Rüdiger

    2016-09-15

    Biodiversity loss is widely recognized as a serious global environmental change process. While large-scale metal mining activities do not belong to the top drivers of such change, these operations exert or may intensify pressures on biodiversity by adversely changing habitats, directly and indirectly, at local and regional scales. So far, analyses of global spatial dynamics of mining and its burden on biodiversity focused on the overlap between mines and protected areas or areas of high value for conservation. However, it is less clear how operating metal mines are globally exerting pressure on zones of different biodiversity richness; a similar gap exists for unmined but known mineral deposits. By using vascular plants' diversity as a proxy to quantify overall biodiversity, this study provides a first examination of the global spatial distribution of mines and deposits for five key metals across different biodiversity zones. The results indicate that mines and deposits are not randomly distributed, but concentrated within intermediate and high diversity zones, especially bauxite and silver. In contrast, iron, gold, and copper mines and deposits are closer to a more proportional distribution while showing a high concentration in the intermediate biodiversity zone. Considering the five metals together, 63% and 61% of available mines and deposits, respectively, are located in intermediate diversity zones, comprising 52% of the global land terrestrial surface. 23% of mines and 20% of ore deposits are located in areas of high plant diversity, covering 17% of the land. 13% of mines and 19% of deposits are in areas of low plant diversity, comprising 31% of the land surface. Thus, there seems to be potential for opening new mines in areas of low biodiversity in the future. PMID:27262340

  12. Large-scale variations of the interplanetary magnetic field: Voyager 1 and 2 observations between 1-5 AU

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Lepping, R. P.; Behannon, K. W.; Klein, L. W.; Neubauer, F. M.

    1981-01-01

    Observations by the Voyager 1 and 2 spacecraft of the interplanetary magnetic field between 1 and 5 AU were used to investigate the large scale structure of the IMF in a period of increasing solar activity. The Voyager spacecraft found notable deviations from the Parker axial model. These deviations are attributed both to temporal variations associated with increasing solar activity, and to the effects of fluctuations of the field in the radial direction. The amplitude of the latter fluctuations were found to be large relative to the magnitude of the radial field component itself beyond approximately 3 AU. Both Voyager 1 and Voyager 2 observed decreases with increasing heliocentric distance in the amplitude of transverse fluctuations in the averaged field strength (B) which are consistent with the presence of predominantly undamped Alfven waves in the solar wind, although and necessarily implying the presence of them. Fluctuations in the strength of B (relative to mean field strength) were found to be small in amplitude, with a RMS which is approximately one third of that for the transverse fluctuations and they are essentially independent of distance from the Sun.

  13. Large-Scale Variational Two-Electron Reduced-Density-Matrix-Driven Complete Active Space Self-Consistent Field Methods.

    PubMed

    Fosso-Tande, Jacob; Nguyen, Truong-Son; Gidofalvi, Gergely; DePrince, A Eugene

    2016-05-10

    A large-scale implementation of the complete active space self-consistent field (CASSCF) method is presented. The active space is described using the variational two-electron reduced-density-matrix (v2RDM) approach, and the algorithm is applicable to much larger active spaces than can be treated using configuration-interaction-driven methods. Density fitting or Cholesky decomposition approximations to the electron repulsion integral tensor allow for the simultaneous optimization of large numbers of external orbitals. We have tested the implementation by evaluating singlet-triplet energy gaps in the linear polyacene series and two dinitrene biradical compounds. For the acene series, we report computations that involve active spaces consisting of as many as 50 electrons in 50 orbitals and the simultaneous optimization of 1892 orbitals. For the dinitrene compounds, we find that the singlet-triplet gaps obtained from v2RDM-driven CASSCF with partial three-electron N-representability conditions agree with those obtained from configuration-interaction-driven approaches to within one-third of 1 kcal mol(-1). When enforcing only the two-electron N-representability conditions, v2RDM-driven CASSCF yields less accurate singlet-triplet energy gaps in these systems, but the quality of the results is still far superior to those obtained from standard single-reference approaches. PMID:27065086

  14. Decreasing spatial variability in precipitation extremes in southwestern China and the local/large-scale influencing factors

    NASA Astrophysics Data System (ADS)

    Liu, Meixian; Xu, Xianli; Sun, Alex

    2015-07-01

    Climate extremes can cause devastating damage to human society and ecosystems. Recent studies have drawn many conclusions about trends in climate extremes, but few have focused on quantitative analysis of their spatial variability and underlying mechanisms. By using the techniques of overlapping moving windows, the Mann-Kendall trend test, correlation, and stepwise regression, this study examined the spatial-temporal variation of precipitation extremes and investigated the potential key factors influencing this variation in southwestern (SW) China, a globally important biodiversity hot spot and climate-sensitive region. Results showed that the changing trends of precipitation extremes were not spatially uniform, but the spatial variability of these precipitation extremes decreased from 1959 to 2012. Further analysis found that atmospheric circulations rather than local factors (land cover, topographic conditions, etc.) were the main cause of such precipitation extremes. This study suggests that droughts or floods may become more homogenously widespread throughout SW China. Hence, region-wide assessments and coordination are needed to help mitigate the economic and ecological impacts.

  15. Interannual drought index variations in Central Europe related to the large-scale atmospheric circulation—application and evaluation of statistical downscaling approaches based on circulation type classifications

    NASA Astrophysics Data System (ADS)

    Beck, Christoph; Philipp, Andreas; Jacobeit, Jucundus

    2015-08-01

    This contribution investigates the relationship between the large-scale atmospheric circulation and interannual variations of the standardized precipitation index (SPI) in Central Europe. To this end, circulation types (CT) have been derived from a variety of circulation type classifications (CTC) applied to daily sea level pressure (SLP) data and mean circulation indices of vorticity ( V), zonality ( Z) and meridionality ( M) have been calculated. Occurrence frequencies of CTs and circulation indices have been utilized as predictors within multiple regression models (MRM) for the estimation of gridded 3-month SPI values over Central Europe, for the period 1950 to 2010. CTC-based MRMs used in the analyses comprise variants concerning the basic method for CT classification, the number of CTs, the size and location of the spatial domain used for CTCs and the exclusive use of CT frequencies or the combined use of CT frequencies and mean circulation indices as predictors. Adequate MRM predictor combinations have been identified by applying stepwise multiple regression analyses within a resampling framework. The performance (robustness) of the resulting MRMs has been quantified based on a leave-one-out cross-validation procedure applying several skill scores. Furthermore, the relative importance of individual predictors has been estimated for each MRM. From these analyses, it can be stated that model skill is improved by (i) the consideration of vorticity characteristics within CTCs, (ii) a relatively small size of the spatial domain to which CTCs are applied and (iii) the inclusion of mean circulation indices. However, model skill exhibits distinct variations between seasons and regions. Whereas promising skill can be stated for the western and northwestern parts of the Central European domain, only unsatisfactory skill is reached in the more continental regions and particularly during summer. Thus, it can be concluded that the presented approaches feature the

  16. Large-scale variations of the interplanetary magnetic field: Voyager 1 and 2 observations between 1-5 AU

    SciTech Connect

    Burlaga, L.F.; Lepping, R.P.; Behannon, K.W.; Klein, L.W.; Neubauer, F.M.

    1982-06-01

    Observations by the Voyager 1 and 2 spacecraft of the interplanetary magnetic field between 1 and 5 AU have been used to investigate the large-scale structure of the IMF in the years 1977 to 1979, a period of increasing solar activity. This complements the Pioneer 10, 11 investigation between 1 and 8.5 AU during 1972--1976 when the sun was less active. In contrast to the good agreement of the Pioneer observations with the ideal field configuration of the Parker spiral model during near solar minimum conditions, the Voyager spacecraft found notable deviations from that configuration. We attribute these deviations both to temporal variations associated with increasing solar activity, and to the effects of fluctuations of the field in the radial direction. The amplitude of the latter fluctuations was found to be large relative to the magnitude of the radial field component itself beyond approximately 3 AU. The IMF sector structure was generally not well-developed during the period of this study. Notable differences were found between Voyager 1 and 2 observations. Differences in the region 1--2 AU are attributed to the substantially different latitudes of the two spacecraft during much of the period. Later differences are most likely associated with the fact that the Voyagers moved through the region between 4 and 5 AU at different times. Both Voyager 1 and 2 observed decreases with increasing heliocentric distance in the amplitude of 'transverse' fluctuations in B that are consistent with the presence of predominantly undamped Alfven waves in the solar wind although not necessarily implying the presence of them. The presence of convective structures, compressive modes, and/or a saturated instability of Alfven waves cannot be excluded by these Voyager results.

  17. Large-scale Observations of a Subauroral Polarization Stream by Midlatitude SuperDARN Radars: Instantaneous Longitudinal Velocity Variations

    NASA Technical Reports Server (NTRS)

    Clausen, L. B. N.; Baker, J. B. H.; Sazykin, S.; Ruohoniemi, J. M.; Greenwald, R. A.; Thomas, E. J.; Shepherd, S. G.; Talaat, E. R.; Bristow, W. A.; Zheng, Y.; Coster, A. J.

    2012-01-01

    We present simultaneous measurements of flow velocities inside a subauroral polarization stream (SAPS) made by six midlatitude high-frequency SuperDARN radars. The instantaneous observations cover three hours of universal time and six hours of magnetic local time (MLT). From velocity variations across the field-of-view of the radars we infer the local 2D flow direction at three different longitudes. We find that the local flow direction inside the SAPS channel is remarkably constant over the course of the event. The flow speed, however, shows significant temporal and spatial variations. After correcting for the radar look direction we are able to accurately determine the dependence of the SAPS velocity on magnetic local time. We find that the SAPS velocity variation with magnetic local time is best described by an exponential function. The average velocity at 00 MLT was 1.2 km/s and it decreased with a spatial e-folding scale of two hours of MLT toward the dawn sector. We speculate that the longitudinal distribution of pressure gradients in the ring current is responsible for this dependence and find these observations in good agreement with results from ring current models. Using TEC measurements we find that the high westward velocities of the SAPS are - as expected - located in a region of low TEC values, indicating low ionospheric conductivities.

  18. An integrated, indicator framework for assessing large-scale variations and change in seasonal timing and phenology (Invited)

    NASA Astrophysics Data System (ADS)

    Betancourt, J. L.; Weltzin, J. F.

    2013-12-01

    As part of an effort to develop an Indicator System for the National Climate Assessment (NCA), the Seasonality and Phenology Indicators Technical Team (SPITT) proposed an integrated, continental-scale framework for understanding and tracking seasonal timing in physical and biological systems. The framework shares several metrics with the EPA's National Climate Change Indicators. The SPITT framework includes a comprehensive suite of national indicators to track conditions, anticipate vulnerabilities, and facilitate intervention or adaptation to the extent possible. Observed, modeled, and forecasted seasonal timing metrics can inform a wide spectrum of decisions on federal, state, and private lands in the U.S., and will be pivotal for international efforts to mitigation and adaptation. Humans use calendars both to understand the natural world and to plan their lives. Although the seasons are familiar concepts, we lack a comprehensive understanding of how variability arises in the timing of seasonal transitions in the atmosphere, and how variability and change translate and propagate through hydrological, ecological and human systems. For example, the contributions of greenhouse warming and natural variability to secular trends in seasonal timing are difficult to disentangle, including earlier spring transitions from winter (strong westerlies) to summer (weak easterlies) patterns of atmospheric circulation; shifts in annual phasing of daily temperature means and extremes; advanced timing of snow and ice melt and soil thaw at higher latitudes and elevations; and earlier start and longer duration of the growing and fire seasons. The SPITT framework aims to relate spatiotemporal variability in surface climate to (1) large-scale modes of natural climate variability and greenhouse gas-driven climatic change, and (2) spatiotemporal variability in hydrological, ecological and human responses and impacts. The hierarchical framework relies on ground and satellite observations

  19. Large-scale tectonic features induced by mantle avalanches with phase, temperature, and pressure lateral variations of viscosity

    NASA Astrophysics Data System (ADS)

    Brunei, David; Machetel, Philippe

    1998-03-01

    million years).The temporal evolution of the convection pattern during an avalanche allows us to propose self-consistent mechanisms for slab migration above the 670 km discontinuity for the birth and disappearance of ridges, the rising of powerful plumes from the CMB, and the creation of low-viscosity zones which may act as a lubricant under continents for fast migration. These results show that the main mantle phase changes, combined with temperature and pressure dependent viscosity, induce convective behavior which provides an explanation for most of the past and present large-scale dynamic behavior of the Earth's global tectonics.

  20. Examiners and Content and Site: Oh My! a National Organization's Investigation of Score Variation in Large-Scale Performance Assessments

    ERIC Educational Resources Information Center

    Sebok, Stefanie S.; Roy, Marguerite; Klinger, Don A.; De Champlain, André F.

    2015-01-01

    Examiner effects and content specificity are two well known sources of construct irrelevant variance that present great challenges in performance-based assessments. National medical organizations that are responsible for large-scale performance based assessments experience an additional challenge as they are responsible for administering…

  1. Large scale study on the variation of RF energy absorption in the head & brain regions of adults and children and evaluation of the SAM phantom conservativeness

    NASA Astrophysics Data System (ADS)

    Keshvari, J.; Kivento, M.; Christ, A.; Bit-Babik, G.

    2016-04-01

    This paper presents the results of two computational large scale studies using highly realistic exposure scenarios, MRI based human head and hand models, and two mobile phone models. The objectives are (i) to study the relevance of age when people are exposed to RF by comparing adult and child heads and (ii) to analyze and discuss the conservativeness of the SAM phantom for all age groups. Representative use conditions were simulated using detailed CAD models of two mobile phones operating between 900 MHz and 1950 MHz including configurations with the hand holding the phone, which were not considered in most previous studies. The peak spatial-average specific absorption rate (psSAR) in the head and the pinna tissues is assessed using anatomically accurate head and hand models. The first of the two mentioned studies involved nine head-, four hand- and two phone-models, the second study included six head-, four hand- and three simplified phone-models (over 400 configurations in total). In addition, both studies also evaluated the exposure using the SAM phantom. Results show no systematic differences between psSAR induced in the adult and child heads. The exposure level and its variation for different age groups may be different for particular phones, but no correlation between psSAR and model age was found. The psSAR from all exposure conditions was compared to the corresponding configurations using SAM, which was found to be conservative in the large majority of cases.

  2. Microstructural variation in the transport direction of a large-scale mid-crustal thrust (Woodroffe Thrust, Central Australia)

    NASA Astrophysics Data System (ADS)

    Wex, Sebastian; Mancktelow, Neil S.; Hawemann, Friedrich; Pennacchioni, Giorgio; Camacho, Alfredo

    2016-04-01

    The over ˜600 km long E-W trending mid-crustal Woodroffe Thrust is one the most prominent structures of a range of large-scale shear zones that developed in the Musgrave Ranges region in Central Australia. During the Petermann Orogeny around 550 Ma the Woodroffe Thrust placed 1.2 Ga granulites onto similarly-aged amphibolite and granulite facies gneisses along a south-dipping plane with a top-to-north shear sense. Due to late-stage open folding of the thrust plane, a nearly continuous N-S profile of 60 km length in the direction of thrusting could be studied for variation in microstructure. The regional P/T variations in the mylonitized footwall (600 to 500 °C at ~ 0.8 GPa from S to N) indicate that the original angle of dip was shallow (~ 10°) towards the south. Along the profile, evidence for fluid-present conditions are effectively absent in the more southerly areas and only present on a local scale in the north, characterizing the regional conditions to be "dry". This is indicated by: 1) only rare syntectonic quartz veins in the footwall; 2) very little sericitization of plagioclase; 3) breakdown of plagioclase to kyanite + garnet, rather than kyanite + clinozoisite; and 4) variable presence of hydrothermally introduced calcite. These changes in P/T conditions and fluid availability are associated with corresponding changes in mineral assemblage and microstructure. Mylonitized dolerites consists of a syn-kinematic assemblage (decreasing modal amounts from left to right) of Pl + Cpx + Grt + Ky + Rt + Ilm ± Opx ± Amp ± Qz in the central/southern areas and Pl + Bt + Amp + Chl + Ilm ± Kfs ± Mag ± Ap in the north. The amount of newly grown garnet decreases towards the north and garnet is generally absent in the northernmost exposures of the Woodroffe Thrust. Mylonitized felsic granulites and granitoids consist of syn-kinematic assemblages of Qz + Pl + Kfs + Grt + Cpx + Ky + Ilm + Rt ± Bt ± Amp ± Opx ± Ap in the south and Qz + Pl + Kfs + Bt + Czo + Grt

  3. Nekton community response to a large-scale Mississippi River discharge: Examining spatial and temporal response to river management

    USGS Publications Warehouse

    Piazza, Bryan P.; La Peyre, M.K.

    2011-01-01

    Freshwater flow is generally held to be one of the most influential factors affecting community structure and production in estuaries. In coastal Louisiana, the Caernarvon Freshwater Diversion (CFD) is managed to control freshwater discharge from the Mississippi River into Breton Sound basin. Operational since 1991, CFD has undergone several changes in management strategy including pulsed spring flooding, which was introduced in 2001. We used a 20-yr time series of fisheries-independent data to investigate how variation in freshwater inflow (i.e., pre- and post-CFD, and pre and post spring pulsing management) influences the downstream nekton community (abundance, diversity, and assemblage). Analyses of long-term data demonstrated that while there were effects from the CFD, they largely involved subtle changes in community structure. Spatially, effects were largely limited to the sites immediately downstream of the diversion and extended only occasionally to more down-estuary sites. Temporally, effects were 1) immediate (detected during spring diversion events) or 2) delayed (detected several months post-diversion). Analysis of river management found that pulsed spring-time inflow resulted in more significant changes in nekton assemblages, likely due to higher discharge rates that 1) increased marsh flooding, thus increasing marsh habitat accessibility for small resident marsh species, and 2) reduced salinity, possibly causing displacement of marine pelagic species down estuary. ?? 2010.

  4. Genome resequencing in Populus: Revealing large-scale genome variation and implications on specialized-trait genomics

    SciTech Connect

    Muchero, Wellington; Labbe, Jessy L; Priya, Ranjan; DiFazio, Steven P; Tuskan, Gerald A

    2014-01-01

    To date, Populus ranks among a few plant species with a complete genome sequence and other highly developed genomic resources. With the first genome sequence among all tree species, Populus has been adopted as a suitable model organism for genomic studies in trees. However, far from being just a model species, Populus is a key renewable economic resource that plays a significant role in providing raw materials for the biofuel and pulp and paper industries. Therefore, aside from leading frontiers of basic tree molecular biology and ecological research, Populus leads frontiers in addressing global economic challenges related to fuel and fiber production. The latter fact suggests that research aimed at improving quality and quantity of Populus as a raw material will likely drive the pursuit of more targeted and deeper research in order to unlock the economic potential tied in molecular biology processes that drive this tree species. Advances in genome sequence-driven technologies, such as resequencing individual genotypes, which in turn facilitates large scale SNP discovery and identification of large scale polymorphisms are key determinants of future success in these initiatives. In this treatise we discuss implications of genome sequence-enable technologies on Populus genomic and genetic studies of complex and specialized-traits.

  5. Large-Scale Variations in Lumber Value Recovery of Yellow Birch and Sugar Maple in Quebec, Canada

    PubMed Central

    Hassegawa, Mariana; Havreljuk, Filip; Ouimet, Rock; Auty, David; Pothier, David; Achim, Alexis

    2015-01-01

    Silvicultural restoration measures have been implemented in the northern hardwoods forests of southern Quebec, Canada, but their financial applicability is often hampered by the depleted state of the resource. To help identify sites most suited for the production of high quality timber, where the potential return on silvicultural investments should be the highest, this study assessed the impact of stand and site characteristics on timber quality in sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britt.). For this purpose, lumber value recovery (LVR), an estimate of the summed value of boards contained in a unit volume of round wood, was used as an indicator of timber quality. Predictions of LVR were made for yellow birch and sugar maple trees contained in a network of more than 22000 temporary sample plots across the Province. Next, stand-level variables were selected and models to predict LVR were built using the boosted regression trees method. Finally, the occurrence of spatial clusters was verified by a hotspot analysis. Results showed that in both species LVR was positively correlated with the stand age and structural diversity index, and negatively correlated with the number of merchantable stems. Yellow birch had higher LVR in areas with shallower soils, whereas sugar maple had higher LVR in regions with deeper soils. The hotspot analysis indicated that clusters of high and low LVR exist across the province for both species. Although it remains uncertain to what extent the variability of LVR may result from variations in past management practices or in inherent site quality, we argue that efforts to produce high quality timber should be prioritized in sites where LVR is predicted to be the highest. PMID:26313689

  6. Large-Scale Variations in Lumber Value Recovery of Yellow Birch and Sugar Maple in Quebec, Canada.

    PubMed

    Hassegawa, Mariana; Havreljuk, Filip; Ouimet, Rock; Auty, David; Pothier, David; Achim, Alexis

    2015-01-01

    Silvicultural restoration measures have been implemented in the northern hardwoods forests of southern Quebec, Canada, but their financial applicability is often hampered by the depleted state of the resource. To help identify sites most suited for the production of high quality timber, where the potential return on silvicultural investments should be the highest, this study assessed the impact of stand and site characteristics on timber quality in sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britt.). For this purpose, lumber value recovery (LVR), an estimate of the summed value of boards contained in a unit volume of round wood, was used as an indicator of timber quality. Predictions of LVR were made for yellow birch and sugar maple trees contained in a network of more than 22000 temporary sample plots across the Province. Next, stand-level variables were selected and models to predict LVR were built using the boosted regression trees method. Finally, the occurrence of spatial clusters was verified by a hotspot analysis. Results showed that in both species LVR was positively correlated with the stand age and structural diversity index, and negatively correlated with the number of merchantable stems. Yellow birch had higher LVR in areas with shallower soils, whereas sugar maple had higher LVR in regions with deeper soils. The hotspot analysis indicated that clusters of high and low LVR exist across the province for both species. Although it remains uncertain to what extent the variability of LVR may result from variations in past management practices or in inherent site quality, we argue that efforts to produce high quality timber should be prioritized in sites where LVR is predicted to be the highest. PMID:26313689

  7. Reconstructing Large-Scale Brain Resting-State Networks from High-Resolution EEG: Spatial and Temporal Comparisons with fMRI.

    PubMed

    Yuan, Han; Ding, Lei; Zhu, Min; Zotev, Vadim; Phillips, Raquel; Bodurka, Jerzy

    2016-03-01

    Functional magnetic resonance imaging (fMRI) studies utilizing measures of hemodynamic signal, such as the blood oxygenation level-dependent (BOLD) signal, have discovered that resting-state brain activities are organized into multiple large-scale functional networks, coined as resting-state networks (RSNs). However, an important limitation of the available fMRI studies is that hemodynamic signals only provide an indirect measure of the neuronal activity. In contrast, electroencephalography (EEG) directly measures electrophysiological activity of the brain. However, little is known about the brain-wide organization of such spontaneous neuronal population signals at the resting state. It is not entirely clear if or how the network structure built upon slowly fluctuating hemodynamic signals is represented in terms of fast, dynamic, and spontaneous neuronal activity. In this study, we investigated the electrophysiological representation of RSNs from simultaneously acquired EEG and fMRI data in the resting human brain. We developed a data-driven analysis approach that reconstructed multiple large-scale electrophysiological networks from high-resolution EEG data alone. The networks derived from EEG were then compared with RSNs independently derived from simultaneously acquired fMRI in their spatial structures as well as temporal dynamics. Results reveal spatially and temporally specific electrophysiological correlates for the fMRI-RSNs. Findings suggest that the spontaneous activity of various large-scale cortical networks is reflected in macroscopic EEG potentials. PMID:26414793

  8. Large-scale variations in ozone and polar stratospheric clouds measured with airborne lidar during formation of the 1987 ozone hole over Antarctica

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Poole, Lamont R.; Mccormick, M. Patrick; Ismail, Syed; Butler, Carolyn F.; Kooi, Susan A.; Szedlmayer, Margaret M.; Jones, Rod; Krueger, Arlin J.; Tuck, Adrian

    1988-01-01

    A joint field experiment between NASA and NOAA was conducted during August to September 1987 to obtain in situ and remote measurements of key gases and aerosols from aircraft platforms during the formation of the ozone (O3) hole over Antarctica. The ER-2 (advanced U-2) and DC-8 aircraft from the NASA Ames Research Center were used in this field experiment. The NASA Langley Research Center's airborne differential absorption lidar (DIAL) system was operated from the DC-8 to obtain profiles of O3 and polar stratospheric clouds in the lower stratosphere during long-range flights over Antarctica from August 28 to September 29, 1987. The airborne DIAL system was configured to transmit simultaneously four laser wavelengths (301, 311, 622, and 1064 nm) above the DC-8 for DIAL measurements of O3 profiles between 11 to 20 km ASL (geometric altitude above sea level) and multiple wavelength aerosol backscatter measurements between 11 to 24 km ASL. A total of 13 DC-8 flights were made over Antarctica with 2 flights reaching the South Pole. Polar stratospheric clouds (PSC's) were detected in multiple thin layers in the 11 to 21 km ASL altitude range with each layer having a typical thickness of less than 1 km. Two types of PSC's were found based on aerosol backscattering ratios: predominantly water ice clouds (type 2) and clouds with scattering characteristics consistent with binary solid nitric acid/water clouds (type 1). Large-scale cross sections of O3 distributions were obtained. The data provides additional information about a potentially important transport mechanism that may influence the O3 budget inside the vortex. There is also some evidence that strong low pressure systems in the troposphere are associated with regions of lower stratospheric O3. This paper discusses the spatial and temporal variations of O3 inside and outside the polar vortex region during the development of the O3 hole and relates these data to other measurements obtained during this field experiment.

  9. Surface forcing of the infrared cooling profile over the Tibetan Plateau. I - Influence of relative longwave radiative heating at high altitude. II - Cooling-rate variation over large-scale plateau domain during summer monsoon transition

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Shi, Lei

    1992-01-01

    The role of the Tibetan Plateau on the behavior of the surface longwave radiation budget is investigated, and the behavior of the vertical profile of longwave cooling over the plateau, including its diurnal variation, is quantified. A medium spectral-resolution IR radiative transfer model utilizing a simple modification for applications in idealized complex (valley) terrain is developed for the investigation. An understanding of how surface and elevation biophysical factors, which are highly variable over the large-scale plateau domain, regulate the spatial distribution of clear-sky IR cooling during the transition phase of the summer monsoon, is described.

  10. Large Scale Spatial Risk and Comparative Prevalence of Borrelia miyamotoi and Borrelia burgdorferi Sensu Lato in Ixodes pacificus

    PubMed Central

    Padgett, Kerry; Bonilla, Denise; Kjemtrup, Anne; Vilcins, Inger-Marie; Yoshimizu, Melissa Hardstone; Hui, Lucia; Sola, Milagros; Quintana, Miguel; Kramer, Vicki

    2014-01-01

    Borrelia miyamotoi is a newly described emerging pathogen transmitted to people by Ixodes species ticks and found in temperate regions of North America, Europe, and Asia. There is limited understanding of large scale entomological risk patterns of B. miyamotoi and of Borreila burgdorferi sensu stricto (ss), the agent of Lyme disease, in western North America. In this study, B. miyamotoi, a relapsing fever spirochete, was detected in adult (n = 70) and nymphal (n = 36) Ixodes pacificus ticks collected from 24 of 48 California counties that were surveyed over a 13 year period. Statewide prevalence of B. burgdorferi sensu lato (sl), which includes B. burgdorferi ss, and B. miyamotoi were similar in adult I. pacificus (0.6% and 0.8%, respectively). In contrast, the prevalence of B. burgdorferi sl was almost 2.5 times higher than B. miyamotoi in nymphal I. pacificus (3.2% versus 1.4%). These results suggest similar risk of exposure to B. burgdorferi sl and B. miyamotoi from adult I. pacificus tick bites in California, but a higher risk of contracting B. burgdorferi sl than B. miyamotoi from nymphal tick bites. While regional risk of exposure to these two spirochetes varies, the highest risk for both species is found in north and central coastal California and the Sierra Nevada foothill region, and the lowest risk is in southern California; nevertheless, tick-bite avoidance measures should be implemented in all regions of California. This is the first study to comprehensively evaluate entomologic risk for B. miyamotoi and B. burgdorferi for both adult and nymphal I. pacificus, an important human biting tick in western North America. PMID:25333277

  11. Seasonal climate information preserved within West Antarctic ice cores and its relation to large-scale atmospheric circulation and regional sea ice variations

    NASA Astrophysics Data System (ADS)

    Küttel, M.; Steig, E. J.; Ding, Q.; Battisti, D. S.

    2010-12-01

    Recent evidence suggests that West Antarctica has been warming since at least the 1950s. With the instrumental record being limited to the mid-20th century, indirect information from stable isotopes (δ18O and δD, hereafter collectively δ) preserved within ice cores have commonly been used to place this warming into a long term context. Here, using a large number of δ records obtained during the International Trans-Antarctic Scientific Expedition (ITASE), past variations in West Antarctic δ are not only investigated over time but also in space. This study therefore provides an important complement to longer records from single locations as e.g. the currently being processed West Antarctic ice sheet (WAIS) Divide ice core. Although snow accumulation rates at the ITASE sites in West Antarctica are variable, they are generally high enough to allow studies on sub-annual scale over the last 50-100 years. Here, we show that variations in δ in this region are strongly related to the state of the large-scale atmospheric circulation as well as sea ice variations in the adjacent Southern Ocean, with important seasonal changes. While a strong relationship to sea ice changes in the Ross and Amundsen Sea as well as to the atmospheric circulation offshore is found during austral fall (MAM) and winter (JJA), only modest correlations are found during spring (SON) and summer (DJF). Interestingly, the correlations with the atmospheric circulation in the latter two seasons have the strongest signal over the Antarctic continent, but not offshore - an important difference to MAM and JJA. These seasonal changes are in good agreement with the seasonally varying predominant circulation: meridional with more frequent storms in the Amundsen Sea during MAM and JJA and more zonal and stable during SON and DJF. The relationship to regional temperature is similarly seasonally variable with highest correlations found during MAM and JJA. Notably, the circulation pattern found to be strongest

  12. On the variation of the ionospheric potential due to large-scale radioactivity enhancement and solar activity

    NASA Astrophysics Data System (ADS)

    Slyunyaev, Nikolay N.; Mareev, Evgeny A.; Zhidkov, Artem A.

    2015-08-01

    Sensitivity of the global electric circuit (GEC) to variations of atmospheric conductivity and current sources is analyzed and discussed. When the undisturbed exponential conductivity profile is assumed all over the Earth, the most substantial changes in the ionospheric potential (IP) are caused by conductivity perturbations inside thunderstorms; if, in addition, conductivity reduction inside thunderstorms and nonelectrified clouds is assumed, the IP becomes less sensitive to conductivity perturbations; besides, the IP is even more sensitive to source current variations than to conductivity. Current source and voltage source descriptions of GEC generators are compared; it is shown that the IP variation may critically depend on the chosen description. As an application, the IP variation due to nuclear weapons testing is studied; it is shown that neither local nor global increase of conductivity in the stratosphere could alone explain the observed 40% IP increase in the 1960s; at the same time this increase might be accounted for by a 40% increase in the source current density or a 46% reduction of the conductivity inside thunderstorms, provided that it was not reduced initially. The IP variation due to solar activity and, in particular, due to solar modulation of galactic cosmic ray flux is also discussed and modeled, which required an adequate parameterization of the rate of atmospheric ion pair production over the solar cycle. It is estimated that the maximum IP variation on the scale of the solar cycle does not exceed 5% of the mean value, unless source current perturbations are taken into account.

  13. Age-Related Wayfinding Differences in Real Large-Scale Environments: Detrimental Motor Control Effects during Spatial Learning Are Mediated by Executive Decline?

    PubMed Central

    Taillade, Mathieu; Sauzéon, Hélène; Arvind Pala, Prashant; Déjos, Marie; Larrue, Florian; Gross, Christian; N’Kaoua, Bernard

    2013-01-01

    The aim of this study was to evaluate motor control activity (active vs. passive condition) with regards to wayfinding and spatial learning difficulties in large-scale spaces for older adults. We compared virtual reality (VR)-based wayfinding and spatial memory (survey and route knowledge) performances between 30 younger and 30 older adults. A significant effect of age was obtained on the wayfinding performances but not on the spatial memory performances. Specifically, the active condition deteriorated the survey measure in all of the participants and increased the age-related differences in the wayfinding performances. Importantly, the age-related differences in the wayfinding performances, after an active condition, were further mediated by the executive measures. All of the results relative to a detrimental effect of motor activity are discussed in terms of a dual task effect as well as executive decline associated with aging. PMID:23843992

  14. Spatial validation of large scale land surface models against monthly land surface temperature patterns using innovative performance metrics.

    NASA Astrophysics Data System (ADS)

    Koch, Julian; Siemann, Amanda; Stisen, Simon; Sheffield, Justin

    2016-04-01

    Land surface models (LSMs) are a key tool to enhance process understanding and to provide predictions of the terrestrial hydrosphere and its atmospheric coupling. Distributed LSMs predict hydrological states and fluxes, such as land surface temperature (LST) or actual evapotranspiration (aET), at each grid cell. LST observations are widely available through satellite remote sensing platforms that enable comprehensive spatial validations of LSMs. In spite of the availability of LST data, most validation studies rely on simple cell to cell comparisons and thus do not regard true spatial pattern information. This study features two innovative spatial performance metrics, namely EOF- and connectivity-analysis, to validate predicted LST patterns by three LSMs (Mosaic, Noah, VIC) over the contiguous USA. The LST validation dataset is derived from global High-Resolution-Infrared-Radiometric-Sounder (HIRS) retrievals for a 30 year period. The metrics are bias insensitive, which is an important feature in order to truly validate spatial patterns. The EOF analysis evaluates the spatial variability and pattern seasonality, and attests better performance to VIC in the warm months and to Mosaic and Noah in the cold months. Further, more than 75% of the LST variability can be captured by a single pattern that is strongly driven by air temperature. The connectivity analysis assesses the homogeneity and smoothness of patterns. The LSMs are most reliable at predicting cold LST patterns in the warm months and vice versa. Lastly, the coupling between aET and LST is investigated at flux tower sites and compared against LSMs to explain the identified LST shortcomings.

  15. Seasonal and spatial variability of nitrosamines and their precursor sources at a large-scale urban drinking water system.

    PubMed

    Woods, Gwen C; Trenholm, Rebecca A; Hale, Bruce; Campbell, Zeke; Dickenson, Eric R V

    2015-07-01

    Nitrosamines are considered to pose greater health risks than currently regulated DBPs and are subsequently listed as a priority pollutant by the EPA, with potential for future regulation. Denver Water, as part of the EPA's Unregulated Contaminant Monitoring Rule 2 (UCMR2) monitoring campaign, found detectable levels of N-nitrosodimethylamine (NDMA) at all sites of maximum residency within the distribution system. To better understand the occurrence of nitrosamines and nitrosamine precursors, Denver Water undertook a comprehensive year-long monitoring campaign. Samples were taken every two weeks to monitor for NDMA in the distribution system, and quarterly sampling events further examined 9 nitrosamines and nitrosamine precursors throughout the treatment and distribution systems. NDMA levels within the distribution system were typically low (>1.3 to 7.2 ng/L) with a remote distribution site (frequently >200 h of residency) experiencing the highest concentrations found. Eight other nitrosamines (N-nitrosomethylethylamine, N-nitrosodiethylamine, N-nitroso-di-n-propylamine, N-nitroso-di-n-butylamine, N-nitroso-di-phenylamine, N-nitrosopyrrolidine, N-nitrosopiperidine, N-nitrosomorpholine) were also monitored but none of these 8, or precursors of these 8 [as estimated with formation potential (FP) tests], were detected anywhere in raw, partially-treated or distribution samples. Throughout the year, there was evidence that seasonality may impact NDMA formation, such that lower temperatures (~5-10°C) produced greater NDMA than during warmer months. The year of sampling further provided evidence that water quality and weather events may impact NDMA precursor loads. Precursor loading estimates demonstrated that NDMA precursors increased during treatment (potentially from cationic polymer coagulant aids). The precursor analysis also provided evidence that precursors may have increased further within the distribution system itself. This comprehensive study of a large-scale

  16. A Capacity Design Method of Distributed Battery Storage for Controlling Power Variation with Large-Scale Photovoltaic Sources in Distribution Network

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yasuhiro; Sawa, Toshiyuki; Gunji, Keiko; Yamazaki, Jun; Watanabe, Masahiro

    A design method for distributed battery storage capacity has been developed for evaluating battery storage advantage on demand-supply imbalance control in distribution systems with which large-scale home photovoltaic powers connected. The proposed method is based on a linear storage capacity minimization model with design basis demand load and photovoltaic output time series subjective to battery management constraints. The design method has been experimentally applied to a sample distribution system with substation storage and terminal area storage. From the numerical results, the developed method successfully clarifies the charge-discharge control and stored power variation, satisfies peak cut requirement, and pinpoints the minimum distributed storage capacity.

  17. Neurocognitive stages of spatial cognitive mapping measured during free exploration of a large-scale virtual environment.

    PubMed

    Plank, Markus; Snider, Joseph; Kaestner, Erik; Halgren, Eric; Poizner, Howard

    2015-02-01

    Using a novel, fully mobile virtual reality paradigm, we investigated the EEG correlates of spatial representations formed during unsupervised exploration. On day 1, subjects implicitly learned the location of 39 objects by exploring a room and popping bubbles that hid the objects. On day 2, they again popped bubbles in the same environment. In most cases, the objects hidden underneath the bubbles were in the same place as on day 1. However, a varying third of them were misplaced in each block. Subjects indicated their certainty that the object was in the same location as the day before. Compared with bubble pops revealing correctly placed objects, bubble pops revealing misplaced objects evoked a decreased negativity starting at 145 ms, with scalp topography consistent with generation in medial parietal cortex. There was also an increased negativity starting at 515 ms to misplaced objects, with scalp topography consistent with generation in inferior temporal cortex. Additionally, misplaced objects elicited an increase in frontal midline theta power. These findings suggest that the successive neurocognitive stages of processing allocentric space may include an initial template matching, integration of the object within its spatial cognitive map, and memory recall, analogous to the processing negativity N400 and theta that support verbal cognitive maps in humans. PMID:25376779

  18. Large-Scale Variation in Forest Carbon Turnover Rate and its Relation to Climate - Remote Sensing vs. Global Vegetation Models

    NASA Astrophysics Data System (ADS)

    Carvalhais, N.; Thurner, M.; Beer, C.; Forkel, M.; Rademacher, T. T.; Santoro, M.; Tum, M.; Schmullius, C.

    2015-12-01

    While vegetation productivity is known to be strongly correlated to climate, there is a need for an improved understanding of the underlying processes of vegetation carbon turnover and their importance at a global scale. This shortcoming has been due to the lack of spatially extensive information on vegetation carbon stocks, which we recently have been able to overcome by a biomass dataset covering northern boreal and temperate forests originating from radar remote sensing. Based on state-of-the-art products on biomass and NPP, we are for the first time able to study the relation between carbon turnover rate and a set of climate indices in northern boreal and temperate forests. The implementation of climate-related mortality processes, for instance drought, fire, frost or insect effects, is often lacking or insufficient in current global vegetation models. In contrast to our observation-based findings, investigated models from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT, are able to reproduce spatial climate - turnover rate relationships only to a limited extent. While most of the models compare relatively well to observation-based NPP, simulated vegetation carbon stocks are severely biased compared to our biomass dataset. Current limitations lead to considerable uncertainties in the estimated vegetation carbon turnover, contributing substantially to the forest feedback to climate change. Our results are the basis for improving mortality concepts in global vegetation models and estimating their impact on the land carbon balance.

  19. Large-scale spatial variability of riverbed temperature gradients in Snake River fall Chinook salmon spawning areas

    SciTech Connect

    Hanrahan, Timothy P.

    2007-02-01

    In the Snake River basin of the Pacific northwestern United States, hydroelectric dam operations are often based on the predicted emergence timing of salmon fry from the riverbed. The spatial variability and complexity of surface water and riverbed temperature gradients results in emergence timing predictions that are likely to have large errors. The objectives of this study were to quantify the thermal heterogeneity between the river and riverbed in fall Chinook salmon spawning areas and to determine the effects of thermal heterogeneity on fall Chinook salmon emergence timing. This study quantified river and riverbed temperatures at 15 fall Chinook salmon spawning sites distributed in two reaches throughout 160 km of the Snake River in Hells Canyon, Idaho, USA, during three different water years. Temperatures were measured during the fall Chinook salmon incubation period with self-contained data loggers placed in the river and at three different depths below the riverbed surface. At all sites temperature increased with depth into the riverbed, including significant differences (p<0.05) in mean water temperature of up to 3.8°C between the river and the riverbed among all the sites. During each of the three water years studied, river and riverbed temperatures varied significantly among all the study sites, among the study sites within each reach, and between sites located in the two reaches. Considerable variability in riverbed temperatures among the sites resulted in fall Chinook salmon emergence timing estimates that varied by as much as 55 days, depending on the source of temperature data used for the estimate. Monitoring of riverbed temperature gradients at a range of spatial scales throughout the Snake River would provide better information for managing hydroelectric dam operations, and would aid in the design and interpretation of future empirical research into the ecological significance of physical riverine processes.

  20. Medium and large-scale variations of dynamo-induced electric fields from AE ion drift measurements

    NASA Technical Reports Server (NTRS)

    Coley, W. R.; Mcclure, J. P.

    1986-01-01

    Current models of the low latitude electric field are largely based on data from incoherent scatter radars. These observations are extended through the addition of the rather extensive high quality electric field measurements from the Ion Drift Meter (IDM) aboard the Atmosphere Explorer (AE) spacecraft. Some preliminary results obtained from the Unified Abstract files of satellite AE-E are presented. This satellite was active from the end of 1975 through June 1981 in various elliptical and circular orbits having an inclination near 20 deg. The resulting data can be examined for the variation of ion drift with latitude, longitude, season, solar cycle, altitude, and magnetic activity. The results presented deal primarily with latitudinal variations of the drift features. Diagrams of data are given and briefly interpreted. The preliminary results presented here indicate that IDM data from the AE and the more recent Dynamics Explorer B spacecraft should continue to disclose some interesting and previously unobserved dynamical features of the low latitude F region.

  1. Large-scale variations of thermal electron parameters in the solar wind between 0.3 and 1 AU

    NASA Astrophysics Data System (ADS)

    1990-05-01

    Variations of thermal electron parameters in the solar wind are investigated using data obtained from the Helios probes in the years from 1974 to 1976, shortly before solar minimum, at heliocentric distances ranging from 0.3 to 1 AU. The main part of the present analysis is based on Helios 2 data obtained in 1976. Variations across the sector structure of the interplanetary magnetic field (IMF) and across the plasma stream structures are studied. These studies support the hypothesis that the thermal electron properties, i.e., the electron temperatures, the core temperatures, the heat flux, and the normalized heat flux, are strongly correlated with the distance from the neutral sheet in the IMF (implying also a correlation with the plasma stream structures). The results do not indicate significant electron heating in compression regions. Also, power laws for the variations of the electron parameters with distance from the Sun as well as polytrope laws are derived for different solar wind structures and distance ranges. The core temperatures, determined by bi-Maxwellian fits to the electron distributions below 20 or 30 eV, mostly decrease faster with distance from the Sun than the electron temperatures Te∥ and Te⊥, parallel and perpendicular to the magnetic field, respectively, as determined from the entire electron distributions. Most of the Helios 2 observations indicate that the radial profiles of electron temperatures and of electron heat flux tend to be flatter in high-speed streams embedded within the interior of magnetic sectors than in the slow- and intermediate-speed solar wind and in compression regions mostly at or near sector boundaries. For high-speed streams, the Helios data indicate a flattening of the radial profiles for Te⊥ with increasing distance from the Sun. For Te∥ this effect is not as evident in the case of Helios 2 data but is indicated by Helios 1 data. Analogous trends are observed for most of the derived polytrope indices for the

  2. How Coriolis forces can limit the spatial extent of sediment deposition of a large-scale turbidity current

    NASA Astrophysics Data System (ADS)

    Wells, Mathew G.

    2009-06-01

    The rotation rate of the Earth controls the deposition scale of turbidity currents when their flow transit-time is comparable to one day. Using laboratory experiments it is shown that the maximum length-scale L of deposition is set by the scale where the Rossby number of the current is equal to one. The dimensionless Rossby number is defined as Ro = U / fL, where U is a depth-averaged velocity of the turbidity current and f is the Coriolis parameter. In these new laboratory experiments the Coriolis parameter is varied by changing the platform rotation rate and there is good agreement between experimental observations and the prediction that the extent of the deposition scales as L ~ (4 / π) 1/4( g' V / f) 1/4, where g' is the reduced gravity and V the initial volume of the sediment-laden material. This scaling implies that the depositional patterns will vary with latitude, and that at higher latitudes one would expect smaller, thicker deposits. Using this scaling implies that the 200-400 km spatial extent of the turbidite arising during the 1929 Grand Banks earthquake had Ro ~ 1, and so Coriolis forces controlled the length-scale of the turbidite deposition.

  3. A Novel Joint Spatial-Code Clustered Interference Alignment Scheme for Large-Scale Wireless Sensor Networks

    PubMed Central

    Wu, Zhilu; Jiang, Lihui; Ren, Guanghui; Zhao, Nan; Zhao, Yaqin

    2015-01-01

    Interference alignment (IA) has been put forward as a promising technique which can mitigate interference and effectively increase the throughput of wireless sensor networks (WSNs). However, the number of users is strictly restricted by the IA feasibility condition, and the interference leakage will become so strong that the quality of service will degrade significantly when there are more users than that IA can support. In this paper, a novel joint spatial-code clustered (JSCC)-IA scheme is proposed to solve this problem. In the proposed scheme, the users are clustered into several groups so that feasible IA can be achieved within each group. In addition, each group is assigned a pseudo noise (PN) code in order to suppress the inter-group interference via the code dimension. The analytical bit error rate (BER) expressions of the proposed JSCC-IA scheme are formulated for the systems with identical and different propagation delays, respectively. To further improve the performance of the JSCC-IA scheme in asymmetric networks, a random grouping selection (RGS) algorithm is developed to search for better grouping combinations. Numerical results demonstrate that the proposed JSCC-IA scheme is capable of accommodating many more users to communicate simultaneously in the same frequency band with better performance. PMID:25602270

  4. Variations of mesoscale and large-scale sea ice morphology in the 1984 Marginal Ice Zone Experiment as observed by microwave remote sensing

    NASA Technical Reports Server (NTRS)

    Campbell, W. J.; Josberger, E. G.; Gloersen, P.; Johannessen, O. M.; Guest, P. S.

    1987-01-01

    The data acquired during the summer 1984 Marginal Ice Zone Experiment in the Fram Strait-Greenland Sea marginal ice zone, using airborne active and passive microwave sensors and the Nimbus 7 SMMR, were analyzed to compile a sequential description of the mesoscale and large-scale ice morphology variations during the period of June 6 - July 16, 1984. Throughout the experiment, the long ice edge between northwest Svalbard and central Greenland meandered; eddies were repeatedly formed, moved, and disappeared but the ice edge remained within a 100-km-wide zone. The ice pack behind this alternately diffuse and compact edge underwent rapid and pronounced variations in ice concentration over a 200-km-wide zone. The high-resolution ice concentration distributions obtained in the aircraft images agree well with the low-resolution distributions of SMMR images.

  5. Two dominant modes of winter temperature variations over China and their relationships with large-scale circulations in CMIP5 models

    NASA Astrophysics Data System (ADS)

    Guo, Yan; Zhao, Zongci; Dong, Wenjie

    2016-05-01

    In this paper, we analyze the two dominant modes of winter surface air temperature (SAT) variations over China and their relationships with large-scale circulation anomalies. We then examine the fidelities of 20 individual models participating in the Coupled Model Inter-comparison Project Phase 5 in reproducing these two perspectives. Results showed that the winter SAT variations over China are dominated by two modes, a homogeneous warming pattern and a tripole pattern with warm departure in Northwest and Northeast China and cold departure in central and southern China. Consistent with the previous studies which documented the variations of the two modes are associated with the Siberian high and Arctic Oscillation (AO) anomalies, respectively, it is newly found that the variation of Empirical Orthogonal Function 2 (EOF2) mode is associated with the Northwest Pacific south-north dipole sea surface temperature anomaly in addition to the AO anomaly. Through comparisons with the observations, we identified that eight models outperform the others in simulating the two dominant modes and their relationships with large-scale circulation anomalies. These high-performing models were then selected to project future winter SAT changes over China under the Representative Concentration Pathway 4.5 (RCP4.5) scenario. Based on the multi-model ensemble mean, a nationwide warming was projected relative to the present climatology (1970-1999), with the largest increase in the Tibetan Plateau of 1.45 ± 0.62 °C by the period 2010-2039 and 2.87 ± 0.82 °C by the period 2050-2079; followed by Northeast China, Northwest China, North China, East China, Southwest China, and, finally, Southeast China.

  6. The relationships between large-scale variations in shear velocity, density, and compressional velocity in the Earth's mantle

    NASA Astrophysics Data System (ADS)

    Moulik, P.; Ekström, G.

    2016-04-01

    A large data set of surface wave phase anomalies, body wave travel times, normal-mode splitting functions, and long-period waveforms is used to investigate the scaling between shear velocity, density, and compressional velocity in the Earth's mantle. We introduce a methodology that allows construction of joint models with various levels of scaling complexity (ϱ = dlnρ/dlnvS, ν = dlnvS/dlnvP), in order to detect seismological signatures of chemical heterogeneity. We demonstrate that the data sets considered cannot be fit concurrently with a uniform ν or a positive and uniform ϱ throughout the mantle. The variance reductions to P wave travel times and vP-sensitive modes are up to 40% higher with our preferred model of anisotropic shear and compressional velocity than the recent anisotropic shear velocity model S362ANI+M, which was constructed assuming a uniform ν throughout the mantle. Several features reported in earlier tomographic studies persist after the inclusion of new and larger data sets; anticorrelation between bulk sound and shear velocities in the lowermost mantle as well as an increase in ν with depth in the lower mantle are largely independent of the regularization scheme. When correlations between density and shear velocity variations are imposed in the lowermost mantle, variance reductions of several spheroidal and toroidal modes deteriorate by as much as 40%. Recent measurements of the splitting of 0S2, in particular, are largely incompatible with perfectly correlated shear velocity and density heterogeneity throughout the mantle. A way to significantly improve the fits to various data sets is by allowing independent density perturbations in the lowermost mantle. Our preferred joint model consists of denser-than-average anomalies (˜1% peak to peak) at the base of the mantle roughly coincident with the low-velocity superplumes. The relative variation of shear velocity, density, and compressional velocity in our study disfavors a purely thermal

  7. Recurrent patterning in the daily foraging routes of hamadryas baboons (Papio hamadryas): spatial memory in large-scale versus small-scale space.

    PubMed

    Schreier, Amy L; Grove, Matt

    2014-05-01

    The benefits of spatial memory for foraging animals can be assessed on two distinct spatial scales: small-scale space (travel within patches) and large-scale space (travel between patches). While the patches themselves may be distributed at low density, within patches resources are likely densely distributed. We propose, therefore, that spatial memory for recalling the particular locations of previously visited feeding sites will be more advantageous during between-patch movement, where it may reduce the distances traveled by animals that possess this ability compared to those that must rely on random search. We address this hypothesis by employing descriptive statistics and spectral analyses to characterize the daily foraging routes of a band of wild hamadryas baboons in Filoha, Ethiopia. The baboons slept on two main cliffs--the Filoha cliff and the Wasaro cliff--and daily travel began and ended on a cliff; thus four daily travel routes exist: Filoha-Filoha, Filoha-Wasaro, Wasaro-Wasaro, Wasaro-Filoha. We use newly developed partial sum methods and distribution-fitting analyses to distinguish periods of area-restricted search from more extensive movements. The results indicate a single peak in travel activity in the Filoha-Filoha and Wasaro-Filoha routes, three peaks of travel activity in the Filoha-Wasaro routes, and two peaks in the Wasaro-Wasaro routes; and are consistent with on-the-ground observations of foraging and ranging behavior of the baboons. In each of the four daily travel routes the "tipping points" identified by the partial sum analyses indicate transitions between travel in small- versus large-scale space. The correspondence between the quantitative analyses and the field observations suggest great utility for using these types of analyses to examine primate travel patterns and especially in distinguishing between movement in small versus large-scale space. Only the distribution-fitting analyses are inconsistent with the field observations, which

  8. Large-Scale Evaluation of Common Variation in Regulatory T Cell-Related Genes and Ovarian Cancer Outcome

    PubMed Central

    Charbonneau, Bridget; Moysich, Kirsten B.; Kalli, Kimberly R.; Oberg, Ann L.; Vierkant, Robert A.; Fogarty, Zachary C.; Block, Matthew S.; Maurer, Matthew J.; Goergen, Krista M.; Fridley, Brooke L.; Cunningham, Julie M.; Rider, David N.; Preston, Claudia; Hartmann, Lynn C.; Lawrenson, Kate; Wang, Chen; Tyrer, Jonathan; Song, Honglin; deFazio, Anna; Johnatty, Sharon E.; Doherty, Jennifer A.; Phelan, Catherine M.; Sellers, Thomas A.; Ramirez, Starr M.; Vitonis, Allison F.; Terry, Kathryn L.; Van Den Berg, David; Pike, Malcolm C.; Wu, Anna H.; Berchuck, Andrew; Gentry-Maharaj, Aleksandra; Ramus, Susan J.; Diergaarde, Brenda; Shen, Howard; Jensen, Allan; Menkiszak, Janusz; Cybulski, Cezary; Lubiński, Jan; Ziogas, Argyrios; Rothstein, Joseph H.; McGuire, Valerie; Sieh, Weiva; Lester, Jenny; Walsh, Christine; Vergote, Ignace; Lambrechts, Sandrina; Despierre, Evelyn; Garcia-Closas, Montserrat; Yang, Hannah; Brinton, Louise A.; Spiewankiewicz, Beata; Rzepecka, Iwona K.; Dansonka-Mieszkowska, Agnieszka; Seibold, Petra; Rudolph, Anja; Paddock, Lisa E.; Orlow, Irene; Lundvall, Lene; Olson, Sara H.; Hogdall, Claus K.; Schwaab, Ira; du Bois, Andreas; Harter, Philipp; Flanagan, James M.; Brown, Robert; Paul, James; Ekici, Arif B.; Beckmann, Matthias W.; Hein, Alexander; Eccles, Diana; Lurie, Galina; Hays, Laura E.; Bean, Yukie T.; Pejovic, Tanja; Goodman, Marc T.; Campbell, Ian; Fasching, Peter A.; Konecny, Gottfried; Kaye, Stanley B.; Heitz, Florian; Hogdall, Estrid; Bandera, Elisa V.; Chang-Claude, Jenny; Kupryjanczyk, Jolanta; Wentzensen, Nicolas; Lambrechts, Diether; Karlan, Beth Y.; Whittemore, Alice S.; Culver, Hoda Anton; Gronwald, Jacek; Levine, Douglas A.; Kjaer, Susanne K.; Menon, Usha; Schildkraut, Joellen M.; Pearce, Celeste Leigh; Cramer, Daniel W.; Rossing, Mary Anne; Chenevix-Trench, Georgia; Pharoah, Paul D.P.; Gayther, Simon A.; Ness, Roberta B.; Odunsi, Kunle; Sucheston, Lara E.; Knutson, Keith L.; Goode, Ellen L.

    2014-01-01

    The presence of regulatory T cells (Tregs) in solid tumors is known to play a role in patient survival in ovarian cancer and other malignancies. We assessed inherited genetic variations via 749 tag SNPs in 25 Treg-associated genes (CD28, CTLA4, FOXP3, IDO1, IL10, IL10RA, IL15, 1L17RA, IL23A, IL23R, IL2RA, IL6, IL6R, IL8, LGALS1, LGALS9, MAP3K8, STAT5A, STAT5B, TGFB1, TGFB2, TGFB3, TGFBR1, TGRBR2, and TGFBR3) in relation to ovarian cancer survival. We analyzed genotype and overall survival in 10,084 women with invasive epithelial ovarian cancer, including 5,248 high-grade serous, 1,452 endometrioid, 795 clear cell, and 661 mucinous carcinoma cases of European descent across 28 studies from the Ovarian Cancer Association Consortium (OCAC). The strongest associations were found for endometrioid carcinoma and IL2RA SNPs rs11256497 [HR=1.42, 95% CI: 1.22–1.64; p=5.7 × 10−6], rs791587 [HR=1.36, 95% CI:1.17–1.57; p=6.2 × 10−5], rs2476491 [HR=1.40, 95% CI: 1.191.64; p=5.6 × 10−5], and rs10795763 [HR=1.35, 95% CI: 1.17–1.57; p=7.9 × 10−5], and for clear cell carcinoma and CTLA4 SNP rs231775 [HR=0.67, 95% CI: 0.54–0.82; p=9.3 × 10−5] after adjustment for age, study site, population stratification, stage, grade, and oral contraceptive use. The rs231775 allele associated with improved survival in our study also results in an amino acid change in CTLA4 and previously has been reported to be associated with autoimmune conditions. Thus, we found evidence that SNPs in genes related to Tregs appear to play a role in ovarian cancer survival, particularly in patients with clear cell and endometrioid EOC. PMID:24764580

  9. Modelling large-scale spatial variability of soil properties with sequential stochastic simulation conditioned by universal kriging in a Hungarian study site

    NASA Astrophysics Data System (ADS)

    Szatmári, Gábor; Barta, Károly; Pásztor, László

    2015-04-01

    Modelling of large-scale spatial variability of soil properties is a promising subject in soil science, as well as in general environmental research, since the resulted model(s) can be applied to solve various problems. In addition to "purely" map an environmental element, the spatial uncertainty of the map product can deduced, specific areas could be identified and/or delineated (contaminated or endangered regions, plots for fertilization, etc.). Geostatistics, which can be regarded as a subset of statistics specialized in analysis and interpretation of geographically referenced data, offer a huge amount of tools to solve these tasks. Numerous spatial modeling methods have been developed in the past decades based on the regionalized variable theory. One of these techniques is sequential stochastic simulation, which can be conditioned with universal kriging (also referred to as regression kriging). As opposed to universal kriging (UK), sequential simulation conditioned with universal kriging (SSUK) provides not just one but several alternative and equally probable "maps", i.e. realizations. The realizations reproduce the global statistics (e.g. sample histogram, variogram), i.e. they reflect/model the reality in a certain global (and not local!) sense. In this paper we present and test SSUK developed in R-code and its utilizations in a water erosion affected study area. Furthermore, we compare the results from UK and SSUK. For this purpose, two soil variables were selected: soil organic matter (SOM) content and rooting depth (RD). SSUK approach is illustrated with a legacy soil dataset from a study area endangered by water erosion in Central Hungary. Legacy soil data was collected in the end of the 1980s in the framework of the National Land Evaluation Programme. Spatially exhaustive covariates were derived from a digital elevation model and from the land-use-map of the study area. SSUK was built upon a UK prediction system for both variables and 200 realizations

  10. Variations over time in latitudinal distribution of the large-scale magnetic fields in the solar atmosphere at heights from the photosphere to the source surface

    NASA Astrophysics Data System (ADS)

    Akhtemov, Z. S.; Andreyeva, O. A.; Rudenko, G. V.; Stepanian, N. N.; Fainshtein, V. G.

    2015-02-01

    Calculations of magnetic field in the solar atmosphere and the "potential field-source surface" model have been used to study time variations in several parameters of the large-scale magnetic field at various heights during the last four solar cycles. At ten heights from the solar surface (R = Ro) to the source surface (R = 2.5Ro), we have constructed synoptic charts (SC) of the radial component Br of the estimated magnetic field. For these SC, we have identified 10-degree latitudinal zones. Within these zones, we found values of Sp (positive Br values averaged within the latitudinal zone over latitude and longitude), Sm (averaged modulus of negative Br values) and S + fields (a part of the latitudinal zone area (in %) occupied by positive Br values). At lower latitudes, cyclic variations in the Sp + Sm parameter are demonstrated to be similar (but not in detail) to time variations in Wolf numbers. Latitudes of 55° and higher exhibited virtually no cyclic peculiarities of time variations in this parameter. The authors believe that this indicates the diverse nature of the large-scale magnetic field in the near-equatorial and polar regions of the solar atmosphere. At R = 2.5Ro, Sp + Sm cyclic variations are almost invisible at all latitudes and only slightly apparent near the equator. The analysis of S + fields variations revealed that at low latitudes at R = 2.5Ro during solar cycles 21, 22 and ascending phase of cycle 23 there were almost no mixed-polarity periods. However, beginning from the maximum of cycle 23, in the near-equatorial region the mixed polarity was observed until the end of the long solar activity minimum. An assumption has been made that this might have been one of the forerunners and manifestations of the prolonged minimum between cycles 23 and 24. It has been found that during solar activity minima poleward there appears motion of magnetic fields with polarity opposite to that of the field at the pole. We have estimated the velocity of such a

  11. In-stream attenuation of nitrogen and phosphorus from major point source in large-scale watershed: mixed source and long-term variation

    NASA Astrophysics Data System (ADS)

    Chen, X.; Fulda, M.; Keller, A. A.

    2011-12-01

    Increased human activity in agriculture and industry has posed significant impact on natural water bodies and resulted in water quality deterioration. Agricultural non-point source pollution and urban point source discharge from municipal waste water treatment plant are the more recent concerns. Computer models are often used to help assess the fate and transport of pollutant, which involves complex interactions such as adsorption, biochemical reaction and plants uptake. However, it remains to be a challenge to assess the attenuation of total nitrogen and total phosphorus in large-scale watershed where there are significant difference in land use types and soil properties, especially when there are significant temporal variations through a long-term simulation. In this study, a large-scale watershed model in the Ohio River Basin was constructed considering a ten year simulation period. To assess the downstream impacts of increasing or decreasing nutrient loads, a hypothetical waste water treatment plant was added as the point source in different subwatersheds, monitoring the downstream effects. Five scenarios (100 kg/d Ammonia, 100 kg/d Nitrate, 100 kg/d Phosphate, mixed 100 kg/d Ammonia & 100 kg/d Phosphate and mixed 100 kg/d Nitrate & 100 kg/d Phosphate) were examined to assess the attenuation process throughout the 10-years simulation. In addition to significant differences in the attenuation in different subwatersheds, the various loads had complex interrelations. We also observed significant variations in attenuation for short-term simulation, while in long-term, the attenuation factors tended to be stabilized.

  12. Large scale dynamic systems

    NASA Technical Reports Server (NTRS)

    Doolin, B. F.

    1975-01-01

    Classes of large scale dynamic systems were discussed in the context of modern control theory. Specific examples discussed were in the technical fields of aeronautics, water resources and electric power.

  13. Annual transition and seasonal variation of indoor air pollution levels of 2-ethyl-1-hexanol in large-scale buildings in Nagoya, Japan.

    PubMed

    Sakai, Kiyoshi; Kamijima, Michihiro; Shibata, Eiji; Ohno, Hiroyuki; Nakajima, Tamie

    2009-11-01

    2-Ethyl-1-hexanol (2E1H) is a possible causative chemical for sick building symptoms; however, thus far, we do not have a clear understanding of the indoor air pollution levels caused by it. In this study, first, airborne 2E1H concentrations were measured during summer and winter from 2004 to 2007 in 67 rooms of 56 large-scale buildings in Nagoya, Japan, in order to show the seasonal variation of indoor air pollution levels of 2E1H. Then, a follow-up survey was conducted in five rooms of five buildings for more than 2 years in order to establish the annual transition of their 2E1H indoor air pollution levels. 2E1H was found to be one of the predominant volatile organic compounds in the indoor air of large-scale buildings. Its geometric mean concentration was significantly higher during summer (55.4 microg/m3) than during winter (13.7 microg/m3) (p < 0.01), although there was a significant difference in the concentrations among the buildings. High 2E1H concentrations may have been caused by high emission rates of 2E1H from floors, because of the hydrolysis of di(2-ethylhexyl) phthalate in polyvinyl chloride flooring materials or of adhesives containing 2-ethylhexyl moieties. Follow-up observations showed little decrease in the indoor air 2E1H concentrations from one year to the next, although they did show seasonal fluctuations, with an evident increase in concentrations during summer and an evident decrease during winter. PMID:19890564

  14. Incorporation of spatial interactions in location networks to identify critical geo-referenced routes for assessing disease control measures on a large-scale campus.

    PubMed

    Wen, Tzai-Hung; Chin, Wei Chien Benny

    2015-04-01

    Respiratory diseases mainly spread through interpersonal contact. Class suspension is the most direct strategy to prevent the spread of disease through elementary or secondary schools by blocking the contact network. However, as university students usually attend courses in different buildings, the daily contact patterns on a university campus are complicated, and once disease clusters have occurred, suspending classes is far from an efficient strategy to control disease spread. The purpose of this study is to propose a methodological framework for generating campus location networks from a routine administration database, analyzing the community structure of the network, and identifying the critical links and nodes for blocking respiratory disease transmission. The data comes from the student enrollment records of a major comprehensive university in Taiwan. We combined the social network analysis and spatial interaction model to establish a geo-referenced community structure among the classroom buildings. We also identified the critical links among the communities that were acting as contact bridges and explored the changes in the location network after the sequential removal of the high-risk buildings. Instead of conducting a questionnaire survey, the study established a standard procedure for constructing a location network on a large-scale campus from a routine curriculum database. We also present how a location network structure at a campus could function to target the high-risk buildings as the bridges connecting communities for blocking disease transmission. PMID:25874686

  15. Large Scale Computing

    NASA Astrophysics Data System (ADS)

    Capiluppi, Paolo

    2005-04-01

    Large Scale Computing is acquiring an important role in the field of data analysis and treatment for many Sciences and also for some Social activities. The present paper discusses the characteristics of Computing when it becomes "Large Scale" and the current state of the art for some particular application needing such a large distributed resources and organization. High Energy Particle Physics (HEP) Experiments are discussed in this respect; in particular the Large Hadron Collider (LHC) Experiments are analyzed. The Computing Models of LHC Experiments represent the current prototype implementation of Large Scale Computing and describe the level of maturity of the possible deployment solutions. Some of the most recent results on the measurements of the performances and functionalities of the LHC Experiments' testing are discussed.

  16. Spatial Structure of Above-Ground Biomass Limits Accuracy of Carbon Mapping in Rainforest but Large Scale Forest Inventories Can Help to Overcome.

    PubMed

    Guitet, Stéphane; Hérault, Bruno; Molto, Quentin; Brunaux, Olivier; Couteron, Pierre

    2015-01-01

    Precise mapping of above-ground biomass (AGB) is a major challenge for the success of REDD+ processes in tropical rainforest. The usual mapping methods are based on two hypotheses: a large and long-ranged spatial autocorrelation and a strong environment influence at the regional scale. However, there are no studies of the spatial structure of AGB at the landscapes scale to support these assumptions. We studied spatial variation in AGB at various scales using two large forest inventories conducted in French Guiana. The dataset comprised 2507 plots (0.4 to 0.5 ha) of undisturbed rainforest distributed over the whole region. After checking the uncertainties of estimates obtained from these data, we used half of the dataset to develop explicit predictive models including spatial and environmental effects and tested the accuracy of the resulting maps according to their resolution using the rest of the data. Forest inventories provided accurate AGB estimates at the plot scale, for a mean of 325 Mg.ha-1. They revealed high local variability combined with a weak autocorrelation up to distances of no more than10 km. Environmental variables accounted for a minor part of spatial variation. Accuracy of the best model including spatial effects was 90 Mg.ha-1 at plot scale but coarse graining up to 2-km resolution allowed mapping AGB with accuracy lower than 50 Mg.ha-1. Whatever the resolution, no agreement was found with available pan-tropical reference maps at all resolutions. We concluded that the combined weak autocorrelation and weak environmental effect limit AGB maps accuracy in rainforest, and that a trade-off has to be found between spatial resolution and effective accuracy until adequate "wall-to-wall" remote sensing signals provide reliable AGB predictions. Waiting for this, using large forest inventories with low sampling rate (<0.5%) may be an efficient way to increase the global coverage of AGB maps with acceptable accuracy at kilometric resolution. PMID:26402522

  17. Spatial Structure of Above-Ground Biomass Limits Accuracy of Carbon Mapping in Rainforest but Large Scale Forest Inventories Can Help to Overcome

    PubMed Central

    Guitet, Stéphane; Hérault, Bruno; Molto, Quentin; Brunaux, Olivier; Couteron, Pierre

    2015-01-01

    Precise mapping of above-ground biomass (AGB) is a major challenge for the success of REDD+ processes in tropical rainforest. The usual mapping methods are based on two hypotheses: a large and long-ranged spatial autocorrelation and a strong environment influence at the regional scale. However, there are no studies of the spatial structure of AGB at the landscapes scale to support these assumptions. We studied spatial variation in AGB at various scales using two large forest inventories conducted in French Guiana. The dataset comprised 2507 plots (0.4 to 0.5 ha) of undisturbed rainforest distributed over the whole region. After checking the uncertainties of estimates obtained from these data, we used half of the dataset to develop explicit predictive models including spatial and environmental effects and tested the accuracy of the resulting maps according to their resolution using the rest of the data. Forest inventories provided accurate AGB estimates at the plot scale, for a mean of 325 Mg.ha-1. They revealed high local variability combined with a weak autocorrelation up to distances of no more than10 km. Environmental variables accounted for a minor part of spatial variation. Accuracy of the best model including spatial effects was 90 Mg.ha-1 at plot scale but coarse graining up to 2-km resolution allowed mapping AGB with accuracy lower than 50 Mg.ha-1. Whatever the resolution, no agreement was found with available pan-tropical reference maps at all resolutions. We concluded that the combined weak autocorrelation and weak environmental effect limit AGB maps accuracy in rainforest, and that a trade-off has to be found between spatial resolution and effective accuracy until adequate “wall-to-wall” remote sensing signals provide reliable AGB predictions. Waiting for this, using large forest inventories with low sampling rate (<0.5%) may be an efficient way to increase the global coverage of AGB maps with acceptable accuracy at kilometric resolution. PMID

  18. Variations in large-scale tropical cyclone genesis factors over the western North Pacific in the PMIP3 last millennium simulations

    NASA Astrophysics Data System (ADS)

    Yan, Qing; Wei, Ting; Zhang, Zhongshi

    2016-04-01

    Investigation of past tropical cyclone (TC) activity in the Western North Pacific (WNP) is potentially helpful to enable better understanding of future TC behaviors. In this study, we examine variations in large-scale environmental factors important to TC genesis in the last millennium simulations from the Paleoclimate Modelling Intercomparison Project Phase 3 (PMIP3). The results show that potential intensity, a theoretical prediction of the maximum TC intensity, is increased relative to the last millennium in the north part of the WNP in the Medieval Climate Anomaly (MCA; 950-1200 AD) while it is decreased in the Little Ice Age (LIA; 1600-1850 AD). Vertical wind shear that generally inhibits TC genesis is enhanced (reduced) to the south of 20°N and is reduced (enhanced) to the north in the MCA (LIA). Relative humidity (at 600 hPa) that measures the mid-tropospheric moisture content broadly shows an increase (decrease) in the MCA (LIA). A genesis potential index indicates that conditions are generally favorable (unfavorable) for TC formation in the WNP in the MCA (LIA), especially in the northern part. Taking changes in steering flows into account, there may be an increasing (decreasing) favorability for storm strikes in East Asia in the MCA (LIA). The estimated TC activity is consistent with the geological proxies in Japan, but contradicts with the typhoon records in southern China and Taiwan. This model-data discrepancy is attributed to the limitations in both simulations and reconstructions.

  19. Large-Scale Disasters

    NASA Astrophysics Data System (ADS)

    Gad-El-Hak, Mohamed

    "Extreme" events - including climatic events, such as hurricanes, tornadoes, and drought - can cause massive disruption to society, including large death tolls and property damage in the billions of dollars. Events in recent years have shown the importance of being prepared and that countries need to work together to help alleviate the resulting pain and suffering. This volume presents a review of the broad research field of large-scale disasters. It establishes a common framework for predicting, controlling and managing both manmade and natural disasters. There is a particular focus on events caused by weather and climate change. Other topics include air pollution, tsunamis, disaster modeling, the use of remote sensing and the logistics of disaster management. It will appeal to scientists, engineers, first responders and health-care professionals, in addition to graduate students and researchers who have an interest in the prediction, prevention or mitigation of large-scale disasters.

  20. Spatial patterns of groundwater-surface water interactions at the meander-bend scale in a gravel-bed lowland river during a large-scale flow experiment

    NASA Astrophysics Data System (ADS)

    Bray, E. N.; Dunne, T.

    2012-12-01

    Improved characterization of 1) streambed hydraulic conductivity and 2) near-bed and subsurface water temperatures allows better understanding of the spatial patterns of groundwater-surface water exchange in rivers. We measured the effects of a large-scale flow experiment on groundwater-surface water exchange and temperature using fiber optic distributed temperature sensing (DTS), measured temperature in the shallow hyporheic zone (46 cm), and measured streambed saturated hydraulic conductivity (Ksat) over the length of three river meander bends (2 km). Measured channel bed elevation, flow depth, velocity, and bed-material grain size were used to develop a two-dimensional numerical model of the flow field as boundary conditions for a model of the hyporheic flow field. We deployed 2 km of fiber-optic cable directly on top of the riverbed over three pool-riffle sequences each with a different degree of bed mobility. DTS data were collected every 2 m for 32 days (1.5 days at 10 cms, 10 days at 20 cms, 16 days at 10 cms, and 4.5 days at 2-4 cms). Three installations of six hyporheic zone sensors, located near the upstream and downstream ends of the DTS cable, recorded interstitial pore water temperature at depths of 46 cm. During flows of 10 cms, we measured Ksat in the streambed at depths of 60 cm using a groundwater standpipe and backpack permeameter over the length of two meander bends. DTS results showed relatively uniform temperature over the 2-km reach during the initial flow of 10 cms. Near-bed temperatures averaged 15.6°C while pore water temperatures averaged 15.4°C. The 20 cms flow decreased near-bed temperatures to 14.9°C and pore water temperatures averaged 14.7°C. However, during the 20 cms flow, the bed became mobile causing local scour and deposition at three locations and buried the DTS cable with gravel/sand up to 26 cm deep. Our DTS results allowed us to record the transition from near-bed temperatures to shallow subsurface temperatures during a

  1. Impact of interannual changes of large scale circulation and hydrography on the spatial distribution of beaked redfish (Sebastes mentella) in the Irminger Sea

    NASA Astrophysics Data System (ADS)

    Núñez-Riboni, Ismael; Kristinsson, Kristján; Bernreuther, Matthias; van Aken, Hendrik M.; Stransky, Christoph; Cisewski, Boris; Rolskiy, Alexey

    2013-12-01

    This study provides evidence of the influence of hydrography and large scale ocean circulation on the geographical distribution of beaked redfish (Sebastes mentella) in the Irminger Sea on the interannual time scale, from 1992 to 2011. The results reveal the average relationship of adult pelagic redfish to their physical habitat from 100 to 800 m depth: the most preferred latitude, longitude, depth, temperature and salinity for redfish are approximately 58°N, 41°W, 557 m, 4.5 °C and 34.87, respectively. The redfish habitat corresponds in a temperature-salinity (TS) diagram to a mixing triangle between East Greenland Current Water (EGCW), Labrador Sea Water (LSW) and Irminger Current Water (ICW). The geographical centre of mass of the redfish distribution (as revealed by acoustic fish density) indicates displacements from year to year. Changes in hydrographic conditions were investigated in detail for possible reasons for these displacements. Empirical Orthogonal Analysis reveals that maximum variations of water mass volume on an interannual time-scale in the study region correspond to ICW and LSW changes, while EGCW remains comparatively stable. Indices of redfish geographical centroid, LSW volume, ICW temperature and Subpolar Gyre (SPG) intensity suggest that the geographical redfish displacements are closely related to interannual changes of ICW modulated by the SPG intensity with a lag of 1 or 2 years. In comparison, LSW seems to have no impact on the redfish distribution at the studied depth range. The time lag between ICW and redfish displacements indicates an indirect influence of temperature on redfish. Hence, changes of chlorophyll-a (from satellite imagery), as a proxy for primary production, were used in a first approach to study the role of food availability. The analysis is based on acoustic and trawl data from nine expeditions coordinated by the International Council for the Exploration of the Sea (ICES), around 71,000 hydrographic stations from the

  2. Spatial and temporal variation in evapotranspiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatial and temporal variation in evapotranspiration occurs at multiple scales as the result of several different spatial and temporal patterns in precipitation, soil water holding capacity, cloudiness (available energy), types of crops, and residue and tillage management practices. We have often as...

  3. Large-scale dynamics of sandy beach ecosystems in transitional waters of the Southwestern Atlantic Ocean: Species turnover, stability and spatial synchrony

    NASA Astrophysics Data System (ADS)

    Lercari, Diego; Defeo, Omar

    2015-03-01

    Transitional waters (TW) are interfaces between the terrestrial and freshwater environments and the sea. These ecotones are characterized by highly dynamic physico-chemical and hydro-morphologic conditions, resulting in a mosaic of habitats in which species are particularly well adapted to variability. However, sandy beach ecotones occurring along estuarine gradients are rarely addressed from the TW perspective. We conducted a 2-yr study to assess the seasonal dynamics of environmental and macrofaunal descriptors in 16 sandy beaches of the Uruguayan coast in TW defined by the widest estuary of the world (Rio de la Plata). A strong variability in environmental conditions was found at inner estuarine beaches, reflecting the seasonal dynamics of the estuarine discharge. The greatest abundance and species richness found in dissipative oceanic beaches were also characterized by their lowest temporal variability, indicating that macrofaunal communities were more stable towards oceanic conditions, where environmental variability was also lowest. Spatial synchrony was reflected in changes across seasons in the species richness in the TW system. A high turnover of species along spatio-temporal gradients occurring within the TW ecotone was observed. Mollusca and Polychaeta were absent in highly-variable estuarine beaches, irrespective of the morphodynamic state. A functional equivalence between species was found at the extremes of the salinity gradient. The environmental variables that best explained community patterns differed among seasons: in summer and autumn, salinity, wave period and beach width were the main explanatory factors, whereas temperature had a primary influence in winter and morphodynamic variables exerted a major influence in autumn. We highlight the need to consider concurrent variations in estuarine and morphodynamic variables when assessing the spatial distribution of macrofaunal species richness and abundance in sandy beaches occurring along TW.

  4. Large scale tracking algorithms.

    SciTech Connect

    Hansen, Ross L.; Love, Joshua Alan; Melgaard, David Kennett; Karelitz, David B.; Pitts, Todd Alan; Zollweg, Joshua David; Anderson, Dylan Z.; Nandy, Prabal; Whitlow, Gary L.; Bender, Daniel A.; Byrne, Raymond Harry

    2015-01-01

    Low signal-to-noise data processing algorithms for improved detection, tracking, discrimination and situational threat assessment are a key research challenge. As sensor technologies progress, the number of pixels will increase signi cantly. This will result in increased resolution, which could improve object discrimination, but unfortunately, will also result in a significant increase in the number of potential targets to track. Many tracking techniques, like multi-hypothesis trackers, suffer from a combinatorial explosion as the number of potential targets increase. As the resolution increases, the phenomenology applied towards detection algorithms also changes. For low resolution sensors, "blob" tracking is the norm. For higher resolution data, additional information may be employed in the detection and classfication steps. The most challenging scenarios are those where the targets cannot be fully resolved, yet must be tracked and distinguished for neighboring closely spaced objects. Tracking vehicles in an urban environment is an example of such a challenging scenario. This report evaluates several potential tracking algorithms for large-scale tracking in an urban environment.

  5. Large scale traffic simulations

    SciTech Connect

    Nagel, K.; Barrett, C.L.; Rickert, M.

    1997-04-01

    Large scale microscopic (i.e. vehicle-based) traffic simulations pose high demands on computational speed in at least two application areas: (i) real-time traffic forecasting, and (ii) long-term planning applications (where repeated {open_quotes}looping{close_quotes} between the microsimulation and the simulated planning of individual person`s behavior is necessary). As a rough number, a real-time simulation of an area such as Los Angeles (ca. 1 million travellers) will need a computational speed of much higher than 1 million {open_quotes}particle{close_quotes} (= vehicle) updates per second. This paper reviews how this problem is approached in different projects and how these approaches are dependent both on the specific questions and on the prospective user community. The approaches reach from highly parallel and vectorizable, single-bit implementations on parallel supercomputers for Statistical Physics questions, via more realistic implementations on coupled workstations, to more complicated driving dynamics implemented again on parallel supercomputers. 45 refs., 9 figs., 1 tab.

  6. Networks of spatial genetic variation across species

    PubMed Central

    Fortuna, Miguel A.; Albaladejo, Rafael G.; Fernández, Laura; Aparicio, Abelardo; Bascompte, Jordi

    2009-01-01

    Spatial patterns of genetic variation provide information central to many ecological, evolutionary, and conservation questions. This spatial variability has traditionally been analyzed through summary statistics between pairs of populations, therefore missing the simultaneous influence of all populations. More recently, a network approach has been advocated to overcome these limitations. This network approach has been applied to a few cases limited to a single species at a time. The question remains whether similar patterns of spatial genetic variation and similar functional roles for specific patches are obtained for different species. Here we study the networks of genetic variation of four Mediterranean woody plant species inhabiting the same habitat patches in a highly fragmented forest mosaic in Southern Spain. Three of the four species show a similar pattern of genetic variation with well-defined modules or groups of patches holding genetically similar populations. These modules can be thought of as the long-sought-after, evolutionarily significant units or management units. The importance of each patch for the cohesion of the entire network, though, is quite different across species. This variation creates a tremendous challenge for the prioritization of patches to conserve the genetic variation of multispecies assemblages. PMID:19861546

  7. Understanding the recurrent large-scale green tide in the Yellow Sea: temporal and spatial correlations between multiple geographical, aquacultural and biological factors.

    PubMed

    Liu, Feng; Pang, Shaojun; Chopin, Thierry; Gao, Suqin; Shan, Tifeng; Zhao, Xiaobo; Li, Jing

    2013-02-01

    The coast of Jiangsu Province in China - where Ulva prolifera has always been firstly spotted before developing into green tides - is uniquely characterized by a huge intertidal radial mudflat. Results showed that: (1) propagules of U. prolifera have been consistently present in seawater and sediments of this mudflat and varied with locations and seasons; (2) over 50,000 tons of fermented chicken manure have been applied annually from March to May in coastal animal aquaculture ponds and thereafter the waste water has been discharged into the radial mudflat intensifying eutrophication; and (3) free-floating U. prolifera could be stranded in any floating infrastructures in coastal waters including large scale Porphyra farming rafts. For a truly integrated management of the coastal zone, reduction in nutrient inputs, and control of the effluents of the coastal pond systems, are needed to control eutrophication and prevent green tides in the future. PMID:23176870

  8. Modeling spatial variation in microbial degradation of pesticides in soil.

    PubMed

    Ghafoor, Abdul; Moeys, Julien; Stenström, John; Tranter, Grant; Jarvis, Nicholas J

    2011-08-01

    Currently, no general guidance is available on suitable approaches for dealing with spatial variation in the first-order pesticide degradation rate constant k even though it is a very sensitive parameter and often highly variable at the field, catchment, and regional scales. Supported by some mechanistic reasoning, we propose a simple general modeling approach to predict k from the sorption constant, which reflects bioavailability, and easily measurable surrogate variables for microbial biomass/activity (organic carbon and clay contents). The soil depth was also explicitly included as an additional predictor variable. This approach was tested in a meta-analysis of available literature data using bootstrapped partial least-squares regression. It explained 73% of the variation in k for the 19 pesticide-study combinations (n = 212) in the database. When 4 of the 19 pesticide-study combinations were excluded (n = 169), the approach explained 80% of the variation in the degradation rate constant. We conclude that the approach shows promise as an effective way to account for the effects of bioavailability and microbial activity on microbial pesticide degradation in large-scale model applications. PMID:21682283

  9. The large-scale distribution of galaxies

    NASA Technical Reports Server (NTRS)

    Geller, Margaret J.

    1989-01-01

    The spatial distribution of galaxies in the universe is characterized on the basis of the six completed strips of the Harvard-Smithsonian Center for Astrophysics redshift-survey extension. The design of the survey is briefly reviewed, and the results are presented graphically. Vast low-density voids similar to the void in Bootes are found, almost completely surrounded by thin sheets of galaxies. Also discussed are the implications of the results for the survey sampling problem, the two-point correlation function of the galaxy distribution, the possibility of detecting large-scale coherent flows, theoretical models of large-scale structure, and the identification of groups and clusters of galaxies.

  10. Quantifying rare, deleterious variation in 12 human cytochrome P450 drug-metabolism genes in a large-scale exome dataset

    PubMed Central

    Gordon, Adam S.; Tabor, Holly K.; Johnson, Andrew D.; Snively, Beverly M.; Assimes, Themistocles L.; Auer, Paul L.; Ioannidis, John P.A.; Peters, Ulrike; Robinson, Jennifer G.; Sucheston, Lara E.; Wang, Danxin; Sotoodehnia, Nona; Rotter, Jerome I.; Psaty, Bruce M.; Jackson, Rebecca D.; Herrington, David M.; O'Donnell, Christopher J.; Reiner, Alexander P.; Rich, Stephen S.; Rieder, Mark J.; Bamshad, Michael J.; Nickerson, Deborah A.

    2014-01-01

    The study of genetic influences on drug response and efficacy (‘pharmacogenetics’) has existed for over 50 years. Yet, we still lack a complete picture of how genetic variation, both common and rare, affects each individual's responses to medications. Exome sequencing is a promising alternative method for pharmacogenetic discovery as it provides information on both common and rare variation in large numbers of individuals. Using exome data from 2203 AA and 4300 Caucasian individuals through the NHLBI Exome Sequencing Project, we conducted a survey of coding variation within 12 Cytochrome P450 (CYP) genes that are collectively responsible for catalyzing nearly 75% of all known Phase I drug oxidation reactions. In addition to identifying many polymorphisms with known pharmacogenetic effects, we discovered over 730 novel nonsynonymous alleles across the 12 CYP genes of interest. These alleles include many with diverse functional effects such as premature stop codons, aberrant splicesites and mutations at conserved active site residues. Our analysis considering both novel, predicted functional alleles as well as known, actionable CYP alleles reveals that rare, deleterious variation contributes markedly to the overall burden of pharmacogenetic alleles within the populations considered, and that the contribution of rare variation to this burden is over three times greater in AA individuals as compared with Caucasians. While most of these impactful alleles are individually rare, 7.6–11.7% of individuals interrogated in the study carry at least one newly described potentially deleterious alleles in a major drug-metabolizing CYP. PMID:24282029

  11. Developing a large-scale model to predict the effects of land use and climatic variation on the biological condition of USA streams and rivers

    EPA Science Inventory

    The US EPA’s National Rivers and Streams Assessment (NRSA) uses spatially balanced sampling to estimate the proportion of streams within the continental US (CONUS) that fail to support healthy biological communities. However, to manage these systems, we also must understand...

  12. Spatial variation of organic sulfur in coal

    SciTech Connect

    Wert, C.A.; Tseng, B.H.; Hsieh, K.C.; Buckentin, M.; Ge, Y.P.

    1987-01-01

    Spatial variation of organic sulfur concentration in coals has been generally known for years. The high resolution of the transmission electron microscope permits that variation to be measured more precisely than is possible by bulk techniques; variations may be measured over distances less than 1 /mu/m. Measurement of organic sulfur content using the transmission electron microscope requires use of ultra thin films or very fine powders. We typically use foils less than 1 /mu/m thickness or powders ground to a few /mu/m. The organic sulfur content is proportional to the ratio of the count rate for the sulfur K/alpha/ line to the count rate for the background radiation measured over some convenient energy interval. The proportionality constant is determined using sulfur standards. The technique is highly reliable for sulfur, as is shown in earlier publications. The PIXE method for heavier elements also utilizes the background radiation to permit absolute numerical concentrations to be derived. This paper reports a particular application of the TEM method to determination of the spatial variation of organic sulfur, both within a given maceral and among maceral types. Some of the observations report measurements on powdered specimens, others on foil specimens prepared from bulk coal.

  13. Multiresolution comparison of precipitation datasets for large-scale models

    NASA Astrophysics Data System (ADS)

    Chun, K. P.; Sapriza Azuri, G.; Davison, B.; DeBeer, C. M.; Wheater, H. S.

    2014-12-01

    Gridded precipitation datasets are crucial for driving large-scale models which are related to weather forecast and climate research. However, the quality of precipitation products is usually validated individually. Comparisons between gridded precipitation products along with ground observations provide another avenue for investigating how the precipitation uncertainty would affect the performance of large-scale models. In this study, using data from a set of precipitation gauges over British Columbia and Alberta, we evaluate several widely used North America gridded products including the Canadian Gridded Precipitation Anomalies (CANGRD), the National Center for Environmental Prediction (NCEP) reanalysis, the Water and Global Change (WATCH) project, the thin plate spline smoothing algorithms (ANUSPLIN) and Canadian Precipitation Analysis (CaPA). Based on verification criteria for various temporal and spatial scales, results provide an assessment of possible applications for various precipitation datasets. For long-term climate variation studies (~100 years), CANGRD, NCEP, WATCH and ANUSPLIN have different comparative advantages in terms of their resolution and accuracy. For synoptic and mesoscale precipitation patterns, CaPA provides appealing performance of spatial coherence. In addition to the products comparison, various downscaling methods are also surveyed to explore new verification and bias-reduction methods for improving gridded precipitation outputs for large-scale models.

  14. Soil physical properties of agricultural systems in a large-scale study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A large-scale field study was performed to determine the effects of agricultural management systems on soil physical properties, including their spatial and temporal variations. Replicates were established in 1998 at the Center for Environmental Farming Systems, Goldsboro, North Carolina; replicates...

  15. Large Scale Nanolaminate Deformable Mirror

    SciTech Connect

    Papavasiliou, A; Olivier, S; Barbee, T; Miles, R; Chang, K

    2005-11-30

    This work concerns the development of a technology that uses Nanolaminate foils to form light-weight, deformable mirrors that are scalable over a wide range of mirror sizes. While MEMS-based deformable mirrors and spatial light modulators have considerably reduced the cost and increased the capabilities of adaptive optic systems, there has not been a way to utilize the advantages of lithography and batch-fabrication to produce large-scale deformable mirrors. This technology is made scalable by using fabrication techniques and lithography that are not limited to the sizes of conventional MEMS devices. Like many MEMS devices, these mirrors use parallel plate electrostatic actuators. This technology replicates that functionality by suspending a horizontal piece of nanolaminate foil over an electrode by electroplated nickel posts. This actuator is attached, with another post, to another nanolaminate foil that acts as the mirror surface. Most MEMS devices are produced with integrated circuit lithography techniques that are capable of very small line widths, but are not scalable to large sizes. This technology is very tolerant of lithography errors and can use coarser, printed circuit board lithography techniques that can be scaled to very large sizes. These mirrors use small, lithographically defined actuators and thin nanolaminate foils allowing them to produce deformations over a large area while minimizing weight. This paper will describe a staged program to develop this technology. First-principles models were developed to determine design parameters. Three stages of fabrication will be described starting with a 3 x 3 device using conventional metal foils and epoxy to a 10-across all-metal device with nanolaminate mirror surfaces.

  16. Sensitivity of Caligus rogercresseyi (Boxshall and Bravo 2000) to pyrethroids and azamethiphos measured using bioassay tests-A large scale spatial study.

    PubMed

    Marín, S L; Ibarra, R; Medina, M H; Jansen, P A

    2015-11-01

    The variety of antiparasitics that can be used against caligid copepods is limited and efforts are needed to maintain their efficacies. The objective of this study was to monitor the sensitivity of Caligus rogercresseyi, populations towards antiparasitics based on deltamethrin, cypermethrin and azamethiphos within and across geographic regions. The bioassay design consisted of exposing parasites collected from 23 farms to the different chemotherapeutants at the concentration and exposure times recommended for field treatment, under laboratory conditions, and evaluating the number of dead and live parasites 48h after exposure. Parasites were collected from 23 farms distributed in four macrozones in the Los Lagos region and three macrozones in the Aysén region. Parasite sensitivity was evaluated using a Generalized Linear Mixed Model of the Binomial family (Logit) fit by the maximum likelihood, using the lme4 package in R. Parasite gender, macrozone, and antiparasitics were used as fixed factors and farm was the random factor. The model including all the factors proved to be a useful tool for predicting parasite sensitivity. This approach identified (i) those macrozones with a greater likelihood of finding parasite populations which are more or less sensitive to the three antiparasitics, (ii) cases in which parasite sensitivity to the different antiparasitics varied within a given macrozone, (iii) differences in sensitivity between females and males and (iv) an important random effect associated with farm. The results indicate a spatial variability of parasite sensitivity to antiparasitics which, added to the continuous treatments applied on farms, suggest it is necessary to regularly update the sensitivity status in the macrozones. This would allow managers to improve their decision making processes regarding the type of antiparasitic to be used in a given situation. The one-concentration type bioassay performed in this study allowed us to perform a large spatial

  17. Multi-scale variation of the meridional movement of the western Pacific warm pool and its associated large-scale climate features

    NASA Astrophysics Data System (ADS)

    Zhou, Guojun; Yang, Song; Zheng, Dawei

    2016-05-01

    In this study, we investigated variation of the meridional movement of the western Pacific warm pool (WPWP). The variation was measured by the central latitude (Clat) of the WPWP on various time scales. Its relationships with global sea surface temperature (SST), precipitation, and atmospheric circulation were examined by applying several advanced statistical methods. First, the techniques of wavelet analysis and least-square adjustment were used to depict the time-frequency features and the mean dominant oscillating time scales of the Clat. Then, a multi-stage filtering technique was applied to illustrate the related dominant oscillating signals. We also examined the time-frequency characteristics of the relationships between Clat and the leading modes of the Indo-Pacific oceans by employing a cross-covariance function analysis and a multiple moving-window method. The physical mechanisms for the relationships between Clat and the patterns of SST, precipitation, and atmospheric circulation were discussed. Results indicated that there is a weakening trend in the oscillation of Clat mainly because the quasi-annual oscillation of Clat increases in January-March and decreases in July-September. The semi-annual oscillation of Clat closely interacts with the westerly wind over the summer hemisphere of the tropical western Pacific Ocean and with the easterly wind over the winter hemisphere of the ocean. The interannual component of Clat corresponds to El Niño-Southern Oscillation and the Indian Ocean basin-wide warming or cooling with strengthened oscillations in the 1970s, and the lower-frequency component of Clat closely corresponds to the central Pacific type of El Niño from the 1990s.

  18. Seeing the elephant: Importance of spatial and temporal coverage in a large-scale volunteer-based program to monitor horseshoe crabs

    USGS Publications Warehouse

    Smith, D.R.; Michels, S.F.

    2006-01-01

    As in John Godfrey Saxe's poem about six blind men and an elephant, conclusions drawn from a monitoring program depend critically on where and when observations are made. We examined results from the Delaware Bay horseshoe crab (Limulus polyphemus) spawning survey to evaluate the effect of spatial and temporal coverage on conclusions about spawning activity. Declines due to previously unregulated harvest triggered an increase in monitoring. Although we detected no apparent trend in bay-wide spawning activity for 1999-2005, conclusions would have differed depending on where and when observations were made. For example, spawning activity in May during the shorebird stopover was a poor predictor of spawning activity over the whole season. Observations made only during peak spawning incorrectly suggested that spawning activity increased during 2001-2005. Trends at one place in the bay were not indicative of trends for the whole bay. Many natural resource issues begin like the blind men and the elephant with dispute partially caused by an incomplete picture of the resource. As sufficient time and funds are directed to gathering necessary data using effective sampling designs, a more complete picture can emerge.

  19. Arsenic in the multi-aquifer system of the Mekong Delta, Vietnam: analysis of large-scale spatial trends and controlling factors.

    PubMed

    Erban, Laura E; Gorelick, Steven M; Fendorf, Scott

    2014-06-01

    Groundwater exploitation is rising in the Mekong Delta, Vietnam, potentially exacerbating arsenic contamination from natural sources. We investigate trends and controls on contamination patterns throughout the Delta's multi-aquifer system as observed in a spatially exhaustive data set of arsenic measured in >40,000 wells, 10.5% of which exceed the WHO drinking water standard for arsenic (10 μg/L). We relate strong trends in the distribution of contamination among well samples to explanatory variables derived from 3D ancillary physicochemical data sets using logistic regression models. Parsimonious models describe much of the observed variability in arsenic occurrence, which differs considerably between subsets of wells tapping shallow versus deeper aquifer groups. In the shallowest Holocene-Pleistocene aquifers, arsenic occurrence is best described by distance to the Mekong river channels and delta front, depth, and location within fault-bounded zones of the region. The same model, however, fails to explain observations in the deeper group of Pliocene-Miocene aquifers. Among these deeper units, arsenic occurrence is rare except among older wells in near-river, heavily pumped areas. Our analysis is the first to examine both natural and anthropogenically mediated contributions to the distribution of arsenic throughout the Mekong Delta's multi-aquifer system, with implications for management of similarly affected basins throughout Southeast Asia. PMID:24849074

  20. Assessing the quality of low-spatial resolution remote sensing data and products by independent large-scale estimations at the Valencia and the Alacant Anchor Stations

    NASA Astrophysics Data System (ADS)

    Lopez-Baeza, E.; Cano, A.; Domenech, C.; Fenollar, J.; Ferreira, G.; Ruiz, C.; Saleh, K.; Velazquez, A.; Vidal, S.

    The fundamental objective of the Valencia and the Alacant Anchor Stations is to develop scientific activities addressed towards the validation of low-spatial resolution remote sensing data and products in the framework of Earth Observation Missions such as GERB Geostationary Earth Radiation Budget SMOS Soil Moisture and Ocean Salinity EarthCARE Earth Clouds Aerosols and Radiation Explorer Both Anchor Stations are similar and are located in natural regions where the land uses are also similar vineyards matorral and shrubs and some olive pine and almond trees However both stations belong to two different climate areas On the one hand the Valencia Anchor Station representative area of about 50 x 50 km2 has a continental type of climate with Mediterranean influences and the mean annual precipitation is about 450 mm On the other hand the Alacant Anchor Station representative area of about 10 x 10 km2 has a Mediterranean semi-arid type of climate where the annual mean precipitation is about 250 mm Moreover the Alacant Anchor Station was chosen on the most degraded crop area of the Valencia Region in the Eastern part of Spain Monitoring and comparing meteorological parameters from both Anchor Stations is of great interest to study the interactions between desertification and climate The satellite missions above mentioned are addressed to the estimation of net radiation at the top of the atmosphere GERB already operational and of soil moisture content SMOS to be launched in September 2007 Our interest is the derivation of

  1. Spatial and temporal distributions of contaminant body burden and disease in Gulf of Mexico oyster populations: The role of local and large-scale climatic controls

    NASA Astrophysics Data System (ADS)

    Wilson, E. A.; Powell, E. N.; Wade, T. L.; Taylor, R. J.; Presley, B. J.; Brooks, J. M.

    1992-06-01

    As part of NOAA's Status and Trends Program, oysters were sampled from 43 sites throughout the Gulf of Mexico from Brownsville, Texas, to the Florida Everglades from 1986 to 1989. Oysters were analysed for body burden of a suite of metals and petroleum aromatic hydrocarbons (PAHs), the prevalence and intensity of the oyster pathogen, Perkinsus marinus, and condition index. The contaminants fell into two groups based on the spatial distribution of body burden throughout the Gulf. Arsenic, selenium, mercury and cadmium were characterized by clinal reduction in similarity with distance reminiscent of that followed by mean monthly temperature and precipitation. Zinc, copper, PAHs and silver showed no consistent geographic trend. Within local regions, industrial and agricultural and use and P. marinus prevalence and infection intensity frequently correlated with body burden. Contaminants and biological attributes followed one of three temporal trends. Zinc, copper and PAHs showed concordant shifts over 4 years throughout the eastern and southern Gulf. Mercury and cadmium showed concordant shifts in the northwestern Gulf. Selenium, arsenic, length, condition index and P. marinus prevalence and infection intensity showed concordant shifts throughout most of the entire Gulf. Concordant shifts suggest that climatic factors, the El Niño/Southern Oscillation being one example, exert a strong influence on biological attributes and contaminant body burdens in the Gulf. Correlative factors are those that probably affect or indicate the rate of tissue turnover and the frequency of reproduction; namely, temperature, disease intensity, condition index and length.

  2. Variability in annual recruitment success as a determinant of long-term and large-scale variation in annual production of intertidal Wadden Sea mussels ( Mytilus edulis)

    NASA Astrophysics Data System (ADS)

    Beukema, J. J.; Dekker, R.

    2007-06-01

    To understand the background of the strong variation and recent decline of stocks and production of mussels ( Mytilus edulis) on tidal flats of the Wadden Sea, we analysed long-term (twice-annual for 26 years) and multi-station (15 sites) estimates of numbers, mean individual weights, biomass, and annual production on Balgzand, a 50-km2 tidal-flat area in the westernmost part of the Wadden Sea (The Netherlands). Somatic production was estimated from summed growth increments of soft tissues per half-year period and expressed in ash-free dry mass (AFDM). In adults, positive values in spring/summer regularly alternated with negative values in autumn/winter, when up to ˜25% (mean: 14%) of individual weight gains in the preceding season were lost. No weight losses were observed during the first winter of the life of mussels. The 26-year mean of net somatic tissue production P amounted to 5.5 g AFDM m-2 a-1 at a mean biomass B of 3.2 g AFDM m-2; the ratio P/B varied strongly with age composition of the mussel population and ranged between 0.5 and 3.0 a-1 (mean: 1.7). Within the restricted areas of mussel beds, mean biomass and annual production values were two orders of magnitude higher. In the Wadden Sea, mussel beds cover a typical 1% of extensive tidal flat areas. Numerical densities of recruits showed straight-line relationships with subsequent life-time year-class production. Once recruits had reached an age of ˜10 months, their numbers predicted subsequent production within narrow limits. Production per recruit averaged 0.21 g AFDM for 10-mo recruits and was not related to recruit density. Local variation in annual production varied strongly, with maximal values between mid-tide and low-tide level, where recruitment was also maximal. Production per recruit was higher at low than at high intertidal levels. Frequently failing recruitment is indicated as the main cause of declining mussel stocks in the Wadden Sea. As in other bivalve species, a declining frequency

  3. Improving AFLP analysis of large-scale patterns of genetic variation--a case study with the Central African lianas Haumania spp (Marantaceae) showing interspecific gene flow.

    PubMed

    Ley, A C; Hardy, O J

    2013-04-01

    AFLP markers are often used to study patterns of population genetic variation and gene flow because they offer a good coverage of the nuclear genome, but the reliability of AFLP scoring is critical. To assess interspecific gene flow in two African rainforest liana species (Haumania danckelmaniana, H. liebrechtsiana) where previous evidence of chloroplast captures questioned the importance of hybridization and species boundaries, we developed new AFLP markers and a novel approach to select reliable bands from their degree of reproducibility. The latter is based on the estimation of the broad-sense heritability of AFLP phenotypes, an improvement over classical scoring error rates, which showed that the polymorphism of most AFLP bands was affected by a substantial nongenetic component. Therefore, using a quantitative genetics framework, we also modified an existing estimator of pairwise kinship coefficient between individuals correcting for the limited heritability of markers. Bayesian clustering confirms the recognition of the two Haumania species. Nevertheless, the decay of the relatedness between individuals of distinct species with geographic distance demonstrates that hybridization affects the nuclear genome. In conclusion, although we showed that AFLP markers might be substantially affected by nongenetic factors, their analysis using the new methods developed considerably advanced our understanding of the pattern of gene flow in our model species. PMID:23398575

  4. Spatial and temporal operation of the Scotia Sea ecosystem: a review of large-scale links in a krill centred food web

    PubMed Central

    Murphy, E.J; Watkins, J.L; Trathan, P.N; Reid, K; Meredith, M.P; Thorpe, S.E; Johnston, N.M; Clarke, A; Tarling, G.A; Collins, M.A; Forcada, J; Shreeve, R.S; Atkinson, A; Korb, R; Whitehouse, M.J; Ward, P; Rodhouse, P.G; Enderlein, P; Hirst, A.G; Martin, A.R; Hill, S.L; Staniland, I.J; Pond, D.W; Briggs, D.R; Cunningham, N.J; Fleming, A.H

    2006-01-01

    The Scotia Sea ecosystem is a major component of the circumpolar Southern Ocean system, where productivity and predator demand for prey are high. The eastward-flowing Antarctic Circumpolar Current (ACC) and waters from the Weddell–Scotia Confluence dominate the physics of the Scotia Sea, leading to a strong advective flow, intense eddy activity and mixing. There is also strong seasonality, manifest by the changing irradiance and sea ice cover, which leads to shorter summers in the south. Summer phytoplankton blooms, which at times can cover an area of more than 0.5 million km2, probably result from the mixing of micronutrients into surface waters through the flow of the ACC over the Scotia Arc. This production is consumed by a range of species including Antarctic krill, which are the major prey item of large seabird and marine mammal populations. The flow of the ACC is steered north by the Scotia Arc, pushing polar water to lower latitudes, carrying with it krill during spring and summer, which subsidize food webs around South Georgia and the northern Scotia Arc. There is also marked interannual variability in winter sea ice distribution and sea surface temperatures that is linked to southern hemisphere-scale climate processes such as the El Niño–Southern Oscillation. This variation affects regional primary and secondary production and influences biogeochemical cycles. It also affects krill population dynamics and dispersal, which in turn impacts higher trophic level predator foraging, breeding performance and population dynamics. The ecosystem has also been highly perturbed as a result of harvesting over the last two centuries and significant ecological changes have also occurred in response to rapid regional warming during the second half of the twentieth century. This combination of historical perturbation and rapid regional change highlights that the Scotia Sea ecosystem is likely to show significant change over the next two to three decades, which may

  5. Developing a large-scale model to predict the effects of land use and climatic variation on the biological condition of USA streams and rivers

    NASA Astrophysics Data System (ADS)

    Hill, R. A.; Weber, M.; Leibowitz, S. G.; Olsen, A. R.

    2014-12-01

    The US EPA's National Rivers and Streams Assessment (NRSA) uses spatially balanced sampling to estimate the proportion of streams within the continental US (CONUS) that fail to support healthy biological communities. However, to manage these systems, we also must understand how human land use alters stream communities from their natural condition and how natural factors, such as climate, interact with these effects. We used random forest modeling and data from 1353 streams that NRSA determined to be in "good" or "poor" biological condition (BC) to predict the probable BC of nearly 5.4 million km of stream (National Hydrography Dataset) within the CONUS. BC was best predicted by 5 natural factors (mean discharge, mean annual air temperature [AT], soil water content, topography, major ecoregion) and 2 riparian factors that are easily altered by humans (% riparian urbanization [%Urb], % riparian forest [%Fst] cover). The model correctly predicted BC for 74% of sites, but predicted poor BC slightly more accurately (76%) than good BC (71%). Initial results showed that probability of good BC declined rapidly with increasing %Urb, but this effect leveled off in streams with >7 %Urb. Likewise, probability of good BC increased in streams with >45 %Fst. This model can be used to generate hypotheses to guide future research and test restoration scenarios. For example, BC had a U-shaped relationship with AT, with poorest BCs predicted between 10-15°C. Plots suggested a strong AT-%Fst interaction, where higher %Fst values mitigated this U-shaped response of BC to AT. These ATs correspond to latitudes that receive the greatest combination of solar radiation intensity and duration in July, and we hypothesize that thermal alteration due to riparian disturbance may be negatively affecting BC in these streams. Finally, simulations suggested that restoring riparian forests could increase the number of streams achieving good BC by 60%, and may represent a critical management tool.

  6. Homogenization of Large-Scale Movement Models in Ecology

    USGS Publications Warehouse

    Garlick, M.J.; Powell, J.A.; Hooten, M.B.; McFarlane, L.R.

    2011-01-01

    A difficulty in using diffusion models to predict large scale animal population dispersal is that individuals move differently based on local information (as opposed to gradients) in differing habitat types. This can be accommodated by using ecological diffusion. However, real environments are often spatially complex, limiting application of a direct approach. Homogenization for partial differential equations has long been applied to Fickian diffusion (in which average individual movement is organized along gradients of habitat and population density). We derive a homogenization procedure for ecological diffusion and apply it to a simple model for chronic wasting disease in mule deer. Homogenization allows us to determine the impact of small scale (10-100 m) habitat variability on large scale (10-100 km) movement. The procedure generates asymptotic equations for solutions on the large scale with parameters defined by small-scale variation. The simplicity of this homogenization procedure is striking when compared to the multi-dimensional homogenization procedure for Fickian diffusion,and the method will be equally straightforward for more complex models. ?? 2010 Society for Mathematical Biology.

  7. The oxygen isotope composition, petrology and geochemistry of mare basalts: Evidence for large-scale compositional variation in the lunar mantle

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.; Anand, M.; Greenwood, R. C.; Miller, M. F.; Franchi, I. A.; Russell, S. S.

    2010-12-01

    To investigate the formation and early evolution of the lunar mantle and crust we have analysed the oxygen isotopic composition, titanium content and modal mineralogy of a suite of lunar basalts. Our sample set included eight low-Ti basalts from the Apollo 12 and 15 collections, and 12 high-Ti basalts from Apollo 11 and 17 collections. In addition, we have determined the oxygen isotopic composition of an Apollo 15 KREEP (K - potassium, REE - Rare Earth Element, and P - phosphorus) basalt (sample 15386) and an Apollo 14 feldspathic mare basalt (sample 14053). Our data display a continuum in bulk-rock δ 18O values, from relatively low values in the most Ti-rich samples to higher values in the Ti-poor samples, with the Apollo 11 sample suite partially bridging the gap. Calculation of bulk-rock δ 18O values, using a combination of previously published oxygen isotope data on mineral separates from lunar basalts, and modal mineralogy (determined in this study), match with the measured bulk-rock δ 18O values. This demonstrates that differences in mineral modal assemblage produce differences in mare basalt δ 18O bulk-rock values. Differences between the low- and high-Ti mare basalts appear to be largely a reflection of mantle-source heterogeneities, and in particular, the highly variable distribution of ilmenite within the lunar mantle. Bulk δ 18O variation in mare basalts is also controlled by fractional crystallisation of a few key mineral phases. Thus, ilmenite fractionation is important in the case of high-Ti Apollo 17 samples, whereas olivine plays a more dominant role for the low-Ti Apollo 12 samples. Consistent with the results of previous studies, our data reveal no detectable difference between the Δ 17O of the Earth and Moon. The fact that oxygen three-isotope studies have been unable to detect a measurable difference at such high precisions reinforces doubts about the giant impact hypothesis as presently formulated.

  8. Spatial Variations in Vitreous Oxygen Consumption

    PubMed Central

    Murali, Karthik; Kang, Dongyang; Nazari, Hossein; Scianmarello, Nicholas; Cadenas, Enrique; Tai, Yu-Chong; Kashani, Amir; Humayun, Mark

    2016-01-01

    We investigated the spatial variation of vitreous oxygen consumption in enucleated porcine eyes. A custom made oxygen source was fabricated that could be localized to either the mid or posterior vitreous cavity and steady state vitreous oxygen tension was measured as a function of distance from the source using a commercially available probe. The reaction rate constant of ascorbate oxidation was estimated ex vivo by measuring the change in oxygen tension over time using vitreous harvested from porcine eyes. Vitreous ascorbate from mid and posterior vitreous was measured spectrophotometrically. When the oxygen source was placed in either the mid-vitreous (N = 6) or the posterior vitreous (N = 6), we measured a statistically significant decrease in vitreous oxygen tension as a function of distance from the oxygen source when compared to control experiments without an oxygen source; (p<0.005 for mid-vitreous and p<0.018 for posterior vitreous at all distances). The mid-vitreous oxygen tension change was significantly different from the posterior vitreous oxygen tension change at 2 and 3mm distances from the respective oxygen source (p<0.001). We also found a statistically significant lower concentration of ascorbate in the mid-vitreous as compared to posterior vitreous (p = 0.02). We determined the reaction rate constant, k = 1.61 M-1s-1 ± 0.708 M-1s-1 (SE), of the oxidation of ascorbate which was modeled following a second order rate equation. Our data demonstrates that vitreous oxygen consumption is higher in the posterior vitreous compared to the mid-vitreous. We also show spatial variations in vitreous ascorbate concentration. PMID:26930281

  9. Galaxy clustering on large scales.

    PubMed

    Efstathiou, G

    1993-06-01

    I describe some recent observations of large-scale structure in the galaxy distribution. The best constraints come from two-dimensional galaxy surveys and studies of angular correlation functions. Results from galaxy redshift surveys are much less precise but are consistent with the angular correlations, provided the distortions in mapping between real-space and redshift-space are relatively weak. The galaxy two-point correlation function, rich-cluster two-point correlation function, and galaxy-cluster cross-correlation function are all well described on large scales ( greater, similar 20h-1 Mpc, where the Hubble constant, H0 = 100h km.s-1.Mpc; 1 pc = 3.09 x 10(16) m) by the power spectrum of an initially scale-invariant, adiabatic, cold-dark-matter Universe with Gamma = Omegah approximately 0.2. I discuss how this fits in with the Cosmic Background Explorer (COBE) satellite detection of large-scale anisotropies in the microwave background radiation and other measures of large-scale structure in the Universe. PMID:11607400

  10. Very Large Scale Integration (VLSI).

    ERIC Educational Resources Information Center

    Yeaman, Andrew R. J.

    Very Large Scale Integration (VLSI), the state-of-the-art production techniques for computer chips, promises such powerful, inexpensive computing that, in the future, people will be able to communicate with computer devices in natural language or even speech. However, before full-scale VLSI implementation can occur, certain salient factors must be…

  11. Spatial variations of ocean wave directional spectra from the Seasat synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Beal, R. C.; Gerling, T. W.; Irvine, D. E.; Monaldo, F. M.; Tilley, D. G.

    1986-01-01

    Seasat synthetic aperture radar ocean wave spectra for a 900-km pass are analyzed and interpreted in the context of both their probable generation sources and their surface current and bathymetric modifiers. Systematic vector wavenumber variations of several times the standard error of determination (about 1.5 percent in magnitude and 0.9 deg in direction) occur along the entire 900-km pass. The large-scale spatial variation of a 200-m swell system can be accurately accounted for as a result of dispersion from a distant storm. The more local variations are qualitatively well correlated in position with known currents and bathymetry but show systematic biases that appear partly due to an environmentally dependent instrument transfer function in the regions of high current and highest sea state. There is also substantial evidence that a large angular deviation in the center of the pass is the result of a mesoscale eddy just to the east.

  12. Microfluidic large-scale integration.

    PubMed

    Thorsen, Todd; Maerkl, Sebastian J; Quake, Stephen R

    2002-10-18

    We developed high-density microfluidic chips that contain plumbing networks with thousands of micromechanical valves and hundreds of individually addressable chambers. These fluidic devices are analogous to electronic integrated circuits fabricated using large-scale integration. A key component of these networks is the fluidic multiplexor, which is a combinatorial array of binary valve patterns that exponentially increases the processing power of a network by allowing complex fluid manipulations with a minimal number of inputs. We used these integrated microfluidic networks to construct the microfluidic analog of a comparator array and a microfluidic memory storage device whose behavior resembles random-access memory. PMID:12351675

  13. Spatial and temporal variations of fundamental constants

    NASA Astrophysics Data System (ADS)

    Levshakov, S. A.; Agafonova, I. I.; Molaro, P.; Reimers, D.

    2010-11-01

    Spatial and temporal variations in the electron-to-proton mass ratio, μ, and in the fine-structure constant, α, are not present in the Standard Model of particle physics but they arise quite naturally in grant unification theories, multidimensional theories and in general when a coupling of light scalar fields to baryonic matter is considered. The light scalar fields are usually attributed to a negative pressure substance permeating the entire visible Universe and known as dark energy. This substance is thought to be responsible for a cosmic acceleration at low redshifts, z < 1. A strong dependence of μ and α on the ambient matter density is predicted by chameleon-like scalar field models. Calculations of atomic and molecular spectra show that different transitions have different sensitivities to changes in fundamental constants. Thus, measuring the relative line positions, Δ V, between such transitions one can probe the hypothetical variability of physical constants. In particular, interstellar molecular clouds can be used to test the matter density dependence of μ, since gas density in these clouds is ~15 orders of magnitude lower than that in terrestrial environment. We use the best quality radio spectra of the inversion transition of NH3 (J,K)=(1,1) and rotational transitions of other molecules to estimate the radial velocity offsets, Δ V ≡ Vrot - Vinv. The obtained value of Δ V shows a statistically significant positive shift of 23±4stat±3sys m s-1 (1σ). Being interpreted in terms of the electron-to-proton mass ratio variation, this gives Δμ/μ = (22±4stat±3sys)×10-9. A strong constraint on variation of the quantity F = α2/μ in the Milky Way is found from comparison of the fine-structure transition J=1-0 in atomic carbon C i with the low-J rotational lines in carbon monoxide 13CO arising in the interstellar molecular clouds: |Δ F/F| < 3×10-7. This yields |Δ α/α| < 1.5×10-7 at z = 0. Since extragalactic absorbers have gas densities

  14. Spatial Variation of Soil Phosphorus Within a Drainage Ditch Network

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural drainage ditches serve as P transport pathways from fields to surface waters. Little is known about the spatial variation of P at the soil-water interface within ditch networks. We quantified the spatial variation of surficial (0–5 cm) soil P within vegetated agricultural ditches on a f...

  15. High Speed Networking and Large-scale Simulation in Geodynamics

    NASA Technical Reports Server (NTRS)

    Kuang, Weijia; Gary, Patrick; Seablom, Michael; Truszkowski, Walt; Odubiyi, Jide; Jiang, Weiyuan; Liu, Dong

    2004-01-01

    Large-scale numerical simulation has been one of the most important approaches for understanding global geodynamical processes. In this approach, peta-scale floating point operations (pflops) are often required to carry out a single physically-meaningful numerical experiment. For example, to model convective flow in the Earth's core and generation of the geomagnetic field (geodynamo), simulation for one magnetic free-decay time (approximately 15000 years) with a modest resolution of 150 in three spatial dimensions would require approximately 0.2 pflops. If such a numerical model is used to predict geomagnetic secular variation over decades and longer, with e.g. an ensemble Kalman filter assimilation approach, approximately 30 (and perhaps more) independent simulations of similar scales would be needed for one data assimilation analysis. Obviously, such a simulation would require an enormous computing resource that exceeds the capacity of a single facility currently available at our disposal. One solution is to utilize a very fast network (e.g. 10Gb optical networks) and available middleware (e.g. Globus Toolkit) to allocate available but often heterogeneous resources for such large-scale computing efforts. At NASA GSFC, we are experimenting with such an approach by networking several clusters for geomagnetic data assimilation research. We shall present our initial testing results in the meeting.

  16. Large scale topography of Io

    NASA Technical Reports Server (NTRS)

    Gaskell, R. W.; Synnott, S. P.

    1987-01-01

    To investigate the large scale topography of the Jovian satellite Io, both limb observations and stereographic techniques applied to landmarks are used. The raw data for this study consists of Voyager 1 images of Io, 800x800 arrays of picture elements each of which can take on 256 possible brightness values. In analyzing this data it was necessary to identify and locate landmarks and limb points on the raw images, remove the image distortions caused by the camera electronics and translate the corrected locations into positions relative to a reference geoid. Minimizing the uncertainty in the corrected locations is crucial to the success of this project. In the highest resolution frames, an error of a tenth of a pixel in image space location can lead to a 300 m error in true location. In the lowest resolution frames, the same error can lead to an uncertainty of several km.

  17. Challenges for Large Scale Simulations

    NASA Astrophysics Data System (ADS)

    Troyer, Matthias

    2010-03-01

    With computational approaches becoming ubiquitous the growing impact of large scale computing on research influences both theoretical and experimental work. I will review a few examples in condensed matter physics and quantum optics, including the impact of computer simulations in the search for supersolidity, thermometry in ultracold quantum gases, and the challenging search for novel phases in strongly correlated electron systems. While only a decade ago such simulations needed the fastest supercomputers, many simulations can now be performed on small workstation clusters or even a laptop: what was previously restricted to a few experts can now potentially be used by many. Only part of the gain in computational capabilities is due to Moore's law and improvement in hardware. Equally impressive is the performance gain due to new algorithms - as I will illustrate using some recently developed algorithms. At the same time modern peta-scale supercomputers offer unprecedented computational power and allow us to tackle new problems and address questions that were impossible to solve numerically only a few years ago. While there is a roadmap for future hardware developments to exascale and beyond, the main challenges are on the algorithmic and software infrastructure side. Among the problems that face the computational physicist are: the development of new algorithms that scale to thousands of cores and beyond, a software infrastructure that lifts code development to a higher level and speeds up the development of new simulation programs for large scale computing machines, tools to analyze the large volume of data obtained from such simulations, and as an emerging field provenance-aware software that aims for reproducibility of the complete computational workflow from model parameters to the final figures. Interdisciplinary collaborations and collective efforts will be required, in contrast to the cottage-industry culture currently present in many areas of computational

  18. Spatial variation in demography and population growth rate: the importance of natal location.

    PubMed

    Reid, J M; Bignal, E M; Bignal, S; McCracken, D I; Monaghan, P

    2006-09-01

    1. Understanding the pattern and magnitude of spatial variation in demography and population growth rate (lambda) is key to understanding the structure and dynamics of natural populations. However, such spatial variation is challenging to quantify. We use>20 years of individual life-history data to quantify small- and large-scale spatial variation in demography and lambda within a single population of red-billed choughs Pyrrhocorax pyrrhocorax on Islay, Scotland. Critically, we demonstrate a major importance of an individual's natal rather than current location in driving observed spatial variation. 2. Breeding success (the number of offspring fledged per breeding attempt) varied among individual chough nest sites but did not vary on a larger spatial scale across Islay. 3. The proportion of fledglings observed to survive to recruiting age varied markedly among individual nest sites and also varied more widely across Islay. Spatial capture-mark-recapture models defined two discrete geographical regions where fledgling survival differed significantly: choughs fledged in region 'BGE' were more likely to survive than choughs fledged in region 'CNSW' as both subadults and adults. 4. The asymptotic lambda attributable to breeding attempts in region BGE exceeded unity, and exceeded that attributable to breeding attempts in region CNSW. Relatively productive and unproductive regions therefore exist within this population. 5. Spatial variation in adult survival was better explained by an individual's natal region than the region where that individual settled to breed. Spatial variation in lambda would consequently have remained undetected had survival been measured across resident breeders rather than across individuals fledged in each region. Furthermore, breeding success was a weak predictor of a nest site's estimated productivity of recruits. 6. We therefore describe marked spatial variation in demography and lambda within a single population of a territorial vertebrate

  19. Assessing spatial and seasonal variations in grasslands with spectral reflectances from a helicopter platform

    NASA Astrophysics Data System (ADS)

    Walthall, Charles L.; Middleton, Elizabeth M.

    1992-11-01

    Helicopter-based radiometric measurements of grassland sites were acquired during the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) to quantify the spatial and spectral variations in surface reflectance contributing to variations in albedo and for comparison with surface fluxes. The helicopter instrumentation consisted of an eight-channel modular multiband radiometer (MMR), video, and photographic cameras. Seasonal and spatial variability of the entire FIFE study area were characterized using 20 MMR data sets from five FIFE sites during the four best ("Golden") data collection days of 1987. The means and coefficients of variation for each spectral band were calculated and analyzed as a function of spatial and seasonal domains. Linear models describing simple ratio (SR) and normalized difference vegetation index (NDVI) as functions of several surface variables were tested. All eight MMR bands contributed information beneficial for characterizing spatial and temporal variations, and the most useful bands were the red (MMR3, 0.63-0.68 μm) and the third middle infrared (MMR7, 2.08-2.37 μm). The blue band (MMRl, 0.45-0.52 μm) proved to be valuable, whereas the often utilized near infrared band (MMR4, 0.75-0.88 μm) was among the least important bands for discriminating landscape variations. The SR was more sensitive than the NDVI to variations in the Konza grassland at all scales: intrasite and intersite, between management practices of burning and grazing, and over time. Furthermore, the relationship of the NDVI with leaf area index was curvilinear, whereas the relationship of the SR was linear at low-leaf area index and was improved by the addition of a second variable, the percent of green dry weight biomass. Improvements in data collection methodologies are recommended for future large scale experiments such as the Boreal Ecosystem and Atmosphere Study (BOREAS).

  20. Standing variation in spatially growing populations

    NASA Astrophysics Data System (ADS)

    Fusco, Diana; Gralka, Matti; Kayser, Jona; Hallatschek, Oskar

    Patterns of genetic diversity not only reflect the evolutionary history of a species but they can also determine the evolutionary response to environmental change. For instance, the standing genetic diversity of a microbial population can be key to rescue in the face of an antibiotic attack. While genetic diversity is in general shaped by both demography and evolution, very little is understood when both factors matter, as e.g. for biofilms with pronounced spatial organization. Here, we quantitatively explore patterns of genetic diversity by using microbial colonies and well-mixed test tube populations as antipodal model systems with extreme and very little spatial structure, respectively. We find that Eden model simulations and KPZ theory can remarkably reproduce the genetic diversity in microbial colonies obtained via population sequencing. The excellent agreement allows to draw conclusions on the resilience of spatially-organized populations and to uncover new strategies to contain antibiotic resistance.

  1. Large Scale Homing in Honeybees

    PubMed Central

    Pahl, Mario; Zhu, Hong; Tautz, Jürgen; Zhang, Shaowu

    2011-01-01

    Honeybee foragers frequently fly several kilometres to and from vital resources, and communicate those locations to their nest mates by a symbolic dance language. Research has shown that they achieve this feat by memorizing landmarks and the skyline panorama, using the sun and polarized skylight as compasses and by integrating their outbound flight paths. In order to investigate the capacity of the honeybees' homing abilities, we artificially displaced foragers to novel release spots at various distances up to 13 km in the four cardinal directions. Returning bees were individually registered by a radio frequency identification (RFID) system at the hive entrance. We found that homing rate, homing speed and the maximum homing distance depend on the release direction. Bees released in the east were more likely to find their way back home, and returned faster than bees released in any other direction, due to the familiarity of global landmarks seen from the hive. Our findings suggest that such large scale homing is facilitated by global landmarks acting as beacons, and possibly the entire skyline panorama. PMID:21602920

  2. Curvature constraints from large scale structure

    NASA Astrophysics Data System (ADS)

    Di Dio, Enea; Montanari, Francesco; Raccanelli, Alvise; Durrer, Ruth; Kamionkowski, Marc; Lesgourgues, Julien

    2016-06-01

    We modified the CLASS code in order to include relativistic galaxy number counts in spatially curved geometries; we present the formalism and study the effect of relativistic corrections on spatial curvature. The new version of the code is now publicly available. Using a Fisher matrix analysis, we investigate how measurements of the spatial curvature parameter ΩK with future galaxy surveys are affected by relativistic effects, which influence observations of the large scale galaxy distribution. These effects include contributions from cosmic magnification, Doppler terms and terms involving the gravitational potential. As an application, we consider angle and redshift dependent power spectra, which are especially well suited for model independent cosmological constraints. We compute our results for a representative deep, wide and spectroscopic survey, and our results show the impact of relativistic corrections on spatial curvature parameter estimation. We show that constraints on the curvature parameter may be strongly biased if, in particular, cosmic magnification is not included in the analysis. Other relativistic effects turn out to be subdominant in the studied configuration. We analyze how the shift in the estimated best-fit value for the curvature and other cosmological parameters depends on the magnification bias parameter, and find that significant biases are to be expected if this term is not properly considered in the analysis.

  3. Distribution probability of large-scale landslides in central Nepal

    NASA Astrophysics Data System (ADS)

    Timilsina, Manita; Bhandary, Netra P.; Dahal, Ranjan Kumar; Yatabe, Ryuichi

    2014-12-01

    Large-scale landslides in the Himalaya are defined as huge, deep-seated landslide masses that occurred in the geological past. They are widely distributed in the Nepal Himalaya. The steep topography and high local relief provide high potential for such failures, whereas the dynamic geology and adverse climatic conditions play a key role in the occurrence and reactivation of such landslides. The major geoscientific problems related with such large-scale landslides are 1) difficulties in their identification and delineation, 2) sources of small-scale failures, and 3) reactivation. Only a few scientific publications have been published concerning large-scale landslides in Nepal. In this context, the identification and quantification of large-scale landslides and their potential distribution are crucial. Therefore, this study explores the distribution of large-scale landslides in the Lesser Himalaya. It provides simple guidelines to identify large-scale landslides based on their typical characteristics and using a 3D schematic diagram. Based on the spatial distribution of landslides, geomorphological/geological parameters and logistic regression, an equation of large-scale landslide distribution is also derived. The equation is validated by applying it to another area. For the new area, the area under the receiver operating curve of the landslide distribution probability in the new area is 0.699, and a distribution probability value could explain > 65% of existing landslides. Therefore, the regression equation can be applied to areas of the Lesser Himalaya of central Nepal with similar geological and geomorphological conditions.

  4. Estimation of large-scale dimension densities.

    PubMed

    Raab, C; Kurths, J

    2001-07-01

    We propose a technique to calculate large-scale dimension densities in both higher-dimensional spatio-temporal systems and low-dimensional systems from only a few data points, where known methods usually have an unsatisfactory scaling behavior. This is mainly due to boundary and finite-size effects. With our rather simple method, we normalize boundary effects and get a significant correction of the dimension estimate. This straightforward approach is based on rather general assumptions. So even weak coherent structures obtained from small spatial couplings can be detected with this method, which is impossible by using the Lyapunov-dimension density. We demonstrate the efficiency of our technique for coupled logistic maps, coupled tent maps, the Lorenz attractor, and the Roessler attractor. PMID:11461376

  5. Estimation of large-scale dimension densities

    NASA Astrophysics Data System (ADS)

    Raab, Corinna; Kurths, Jürgen

    2001-07-01

    We propose a technique to calculate large-scale dimension densities in both higher-dimensional spatio-temporal systems and low-dimensional systems from only a few data points, where known methods usually have an unsatisfactory scaling behavior. This is mainly due to boundary and finite-size effects. With our rather simple method, we normalize boundary effects and get a significant correction of the dimension estimate. This straightforward approach is based on rather general assumptions. So even weak coherent structures obtained from small spatial couplings can be detected with this method, which is impossible by using the Lyapunov-dimension density. We demonstrate the efficiency of our technique for coupled logistic maps, coupled tent maps, the Lorenz attractor, and the Roessler attractor.

  6. Analysis of large-scale Martian topography variations. I - Data preparation from earth-based radar, earth-based CO2 spectroscopy, and Mariners 6 and 7 CO2 spectroscopy.

    NASA Technical Reports Server (NTRS)

    Wells, R. A.

    1972-01-01

    Using direct radar ranging of surface heights on Mars and spectrophotometric observations of absorptions produced by carbon dioxide molecules in the Martian atmosphere, data have been obtained on Martian topographical variations at spatial resolutions ranging from about 100 to 1000 km. These data have been studied and analyzed. As a result, a surface height contour map has been produced which clearly reveals a structural complex of blocks and basins whose distribution enhances the magnitude of low-degree surface harmonics. It is emphasized that Mars possesses unexpectedly pronounced topography which can have important geophysical consequences.

  7. Large-Scale Information Systems

    SciTech Connect

    D. M. Nicol; H. R. Ammerlahn; M. E. Goldsby; M. M. Johnson; D. E. Rhodes; A. S. Yoshimura

    2000-12-01

    Large enterprises are ever more dependent on their Large-Scale Information Systems (LSLS), computer systems that are distinguished architecturally by distributed components--data sources, networks, computing engines, simulations, human-in-the-loop control and remote access stations. These systems provide such capabilities as workflow, data fusion and distributed database access. The Nuclear Weapons Complex (NWC) contains many examples of LSIS components, a fact that motivates this research. However, most LSIS in use grew up from collections of separate subsystems that were not designed to be components of an integrated system. For this reason, they are often difficult to analyze and control. The problem is made more difficult by the size of a typical system, its diversity of information sources, and the institutional complexities associated with its geographic distribution across the enterprise. Moreover, there is no integrated approach for analyzing or managing such systems. Indeed, integrated development of LSIS is an active area of academic research. This work developed such an approach by simulating the various components of the LSIS and allowing the simulated components to interact with real LSIS subsystems. This research demonstrated two benefits. First, applying it to a particular LSIS provided a thorough understanding of the interfaces between the system's components. Second, it demonstrated how more rapid and detailed answers could be obtained to questions significant to the enterprise by interacting with the relevant LSIS subsystems through simulated components designed with those questions in mind. In a final, added phase of the project, investigations were made on extending this research to wireless communication networks in support of telemetry applications.

  8. Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective

    PubMed Central

    Cruz-Motta, Juan José; Miloslavich, Patricia; Palomo, Gabriela; Iken, Katrin; Konar, Brenda; Pohle, Gerhard; Trott, Tom; Benedetti-Cecchi, Lisandro; Herrera, César; Hernández, Alejandra; Sardi, Adriana; Bueno, Andrea; Castillo, Julio; Klein, Eduardo; Guerra-Castro, Edlin; Gobin, Judith; Gómez, Diana Isabel; Riosmena-Rodríguez, Rafael; Mead, Angela; Bigatti, Gregorio; Knowlton, Ann; Shirayama, Yoshihisa

    2010-01-01

    Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses. PMID:21179546

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  10. SST/Wind stress mesoscale coupling in the South East Pacific : what drives its spatial and temporal variations ?

    NASA Astrophysics Data System (ADS)

    Oerder, Véra; Colas, François; Echevin, Vincent; Masson, Sebastien; Hourdin, Christophe; Jullien, Swen; Lemarié, Florian

    2015-04-01

    Air-sea interaction studies show that, on the large-scale, the ocean is primarily forced by the atmosphere. However, it has also been evidenced that mesoscale (~10-100 km) oceanic structures, e.g. fronts and eddies, induce an atmospheric response which also affect in return the oceanic mesoscale. In this study we focus on the oceanic feedback on the surface wind stress (SWS) in the Peru-Chile region. Understanding the dynamics of eastern boundary upwelling systems such as the Peru-Chile region is of major interest as these regions host an intense biological activity. These regions are generally poorly represented in global climate models partly because of a misrepresentation of mesoscale processes. The mesoscale activity has been studied quite extensively with ocean models which generally do not take into account the feedback of the ocean mesoscale on the atmospheric forcing. In the Peru-Chile region, mesoscale air-sea interactions studies are needed to evaluate the importance of this feedback. We use a regional coupled model (WRF-NEMO) at ˜ 9 km horizontal resolution to characterize the interaction between sea surface temperature (SST) and SWS. We compare this coupling to observed values. The SST-SWS interaction presents spatial and temporal variations. Spatial variations appear to be related to the large-scale fields (wind steadiness and intensity). We discuss the seasonal variations of the coupling characteristics by examining the underlying mechanisms. We show that here the key mechanism is the momentum vertical mixing response to SST anomalies. This response is mainly modulated by the seasonal variations of the large-scale wind vertical shear.

  11. Spatial variation as a tool for inferring temporal variation and diagnosing types of mechanisms in ecosystems.

    PubMed

    Hammond, Matthew P; Kolasa, Jurek

    2014-01-01

    Ecological processes, like the rise and fall of populations, leave an imprint of their dynamics as a pattern in space. Mining this spatial record for insight into temporal change underlies many applications, including using spatial snapshots to infer trends in communities, rates of species spread across boundaries, likelihood of chaotic dynamics, and proximity to regime shifts. However, these approaches rely on an inherent but undefined link between spatial and temporal variation. We present a quantitative link between a variable's spatial and temporal variation based on established variance-partitioning techniques, and test it for predictive and diagnostic applications. A strong link existed between spatial and regional temporal variation (estimated as Coefficients of Variation or CV's) in 136 variables from three aquatic ecosystems. This association suggests a basis for substituting one for the other, either quantitatively or qualitatively, when long time series are lacking. We further show that weak substitution of temporal for spatial CV results from distortion by specific spatiotemporal patterns (e.g., inter-patch synchrony). Where spatial and temporal CV's do not match, we pinpoint the spatiotemporal causes of deviation in the dynamics of variables and suggest ways that may control for them. In turn, we demonstrate the use of this framework for describing spatiotemporal patterns in multiple ecosystem variables and attributing them to types of mechanisms. Linking spatial and temporal variability makes quantitative the hitherto inexact practice of space-for-time substitution and may thus point to new opportunities for navigating the complex variation of ecosystems. PMID:24586627

  12. Large-scale climatic control on European precipitation

    NASA Astrophysics Data System (ADS)

    Lavers, David; Prudhomme, Christel; Hannah, David

    2010-05-01

    Precipitation variability has a significant impact on society. Sectors such as agriculture and water resources management are reliant on predictable and reliable precipitation supply with extreme variability having potentially adverse socio-economic impacts. Therefore, understanding the climate drivers of precipitation is of human relevance. This research examines the strength, location and seasonality of links between precipitation and large-scale Mean Sea Level Pressure (MSLP) fields across Europe. In particular, we aim to evaluate whether European precipitation is correlated with the same atmospheric circulation patterns or if there is a strong spatial and/or seasonal variation in the strength and location of centres of correlations. The work exploits time series of gridded ERA-40 MSLP on a 2.5˚×2.5˚ grid (0˚N-90˚N and 90˚W-90˚E) and gridded European precipitation from the Ensemble project on a 0.5°×0.5° grid (36.25˚N-74.25˚N and 10.25˚W-24.75˚E). Monthly Spearman rank correlation analysis was performed between MSLP and precipitation. During winter, a significant MSLP-precipitation correlation dipole pattern exists across Europe. Strong negative (positive) correlation located near the Icelandic Low and positive (negative) correlation near the Azores High pressure centres are found in northern (southern) Europe. These correlation dipoles resemble the structure of the North Atlantic Oscillation (NAO). The reversal in the correlation dipole patterns occurs at the latitude of central France, with regions to the north (British Isles, northern France, Scandinavia) having a positive relationship with the NAO, and regions to the south (Italy, Portugal, southern France, Spain) exhibiting a negative relationship with the NAO. In the lee of mountain ranges of eastern Britain and central Sweden, correlation with North Atlantic MSLP is reduced, reflecting a reduced influence of westerly flow on precipitation generation as the mountains act as a barrier to moist

  13. EINSTEIN'S SIGNATURE IN COSMOLOGICAL LARGE-SCALE STRUCTURE

    SciTech Connect

    Bruni, Marco; Hidalgo, Juan Carlos; Wands, David

    2014-10-10

    We show how the nonlinearity of general relativity generates a characteristic nonGaussian signal in cosmological large-scale structure that we calculate at all perturbative orders in a large-scale limit. Newtonian gravity and general relativity provide complementary theoretical frameworks for modeling large-scale structure in ΛCDM cosmology; a relativistic approach is essential to determine initial conditions, which can then be used in Newtonian simulations studying the nonlinear evolution of the matter density. Most inflationary models in the very early universe predict an almost Gaussian distribution for the primordial metric perturbation, ζ. However, we argue that it is the Ricci curvature of comoving-orthogonal spatial hypersurfaces, R, that drives structure formation at large scales. We show how the nonlinear relation between the spatial curvature, R, and the metric perturbation, ζ, translates into a specific nonGaussian contribution to the initial comoving matter density that we calculate for the simple case of an initially Gaussian ζ. Our analysis shows the nonlinear signature of Einstein's gravity in large-scale structure.

  14. Individual Skill Differences and Large-Scale Environmental Learning

    ERIC Educational Resources Information Center

    Fields, Alexa W.; Shelton, Amy L.

    2006-01-01

    Spatial skills are known to vary widely among normal individuals. This project was designed to address whether these individual differences are differentially related to large-scale environmental learning from route (ground-level) and survey (aerial) perspectives. Participants learned two virtual environments (route and survey) with limited…

  15. Large Scale Field Campaign Contributions to Soil Moisture Remote Sensing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Large-scale field experiments have been an essential component of soil moisture remote sensing for over two decades. They have provided test beds for both the technology and science necessary to develop and refine satellite mission concepts. The high degree of spatial variability of soil moisture an...

  16. Spatial variation and density-dependent dispersal in competitive coexistence.

    PubMed Central

    Amarasekare, Priyanga

    2004-01-01

    It is well known that dispersal from localities favourable to a species' growth and reproduction (sources) can prevent competitive exclusion in unfavourable localities (sinks). What is perhaps less well known is that too much emigration can undermine the viability of sources and cause regional competitive exclusion. Here, I investigate two biological mechanisms that reduce the cost of dispersal to source communities. The first involves increasing the spatial variation in the strength of competition such that sources can withstand high rates of emigration; the second involves reducing emigration from sources via density-dependent dispersal. I compare how different forms of spatial variation and modes of dispersal influence source viability, and hence source-sink coexistence, under dominance and pre-emptive competition. A key finding is that, while spatial variation substantially reduces dispersal costs under both types of competition, density-dependent dispersal does so only under dominance competition. For instance, when spatial variation in the strength of competition is high, coexistence is possible (regardless of the type of competition) even when sources experience high emigration rates; when spatial variation is low, coexistence is restricted even under low emigration rates. Under dominance competition, density-dependent dispersal has a strong effect on coexistence. For instance, when the emigration rate increases with density at an accelerating rate (Type III density-dependent dispersal), coexistence is possible even when spatial variation is quite low; when the emigration rate increases with density at a decelerating rate (Type II density-dependent dispersal), coexistence is restricted even when spatial variation is quite high. Under pre-emptive competition, density-dependent dispersal has only a marginal effect on coexistence. Thus, the diversity-reducing effects of high dispersal rates persist under pre-emptive competition even when dispersal is density

  17. Hurricane Directional Wave Spectrum Spatial Variation at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.

    1999-01-01

    On 26 August 1998, hurricane Bonnie was making landfall near Wilmington, NC. The NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 2.2 km height documented the sea surface directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track included both segments along the shoreline and Pamlico Sound as well as far offshore. An animation of the directional wave spectrum spatial variation at landfall will be presented and contrasted with the spatial variation when Bonnie was in the open ocean on 24 August 1998.

  18. Hurricane Directional Wave Spectrum Spatial Variation at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, Edward J.; Wright, C. Wayne; Vandemark, Douglas C.; Krabill, William B.; Garcia, Andrew W.; Houston, Samuel H.; Powell, Mark D.; Black, Peter G.; Marke, Frank D.; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    On 26 August 1998, hurricane Bonnie was making landfall near Wilmington, NC. The NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 2.2 km height documented the sea surface directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track included both segments along the shoreline and Pamlico Sound as well as far offshore. An animation of the directional wave spectrum spatial variation at landfall will be presented and contrasted with the spatial variation when Bonnie was in the open ocean on 24 August 1998.

  19. Large-Scale Reform Comes of Age

    ERIC Educational Resources Information Center

    Fullan, Michael

    2009-01-01

    This article reviews the history of large-scale education reform and makes the case that large-scale or whole system reform policies and strategies are becoming increasingly evident. The review briefly addresses the pre 1997 period concluding that while the pressure for reform was mounting that there were very few examples of deliberate or…

  20. Large-scale infrared scene projectors

    NASA Astrophysics Data System (ADS)

    Murray, Darin A.

    1999-07-01

    Large-scale infrared scene projectors, typically have unique opto-mechanical characteristics associated to their application. This paper outlines two large-scale zoom lens assemblies with different environmental and package constraints. Various challenges and their respective solutions are discussed and presented.

  1. Large scale digital atlases in neuroscience

    NASA Astrophysics Data System (ADS)

    Hawrylycz, M.; Feng, D.; Lau, C.; Kuan, C.; Miller, J.; Dang, C.; Ng, L.

    2014-03-01

    Imaging in neuroscience has revolutionized our current understanding of brain structure, architecture and increasingly its function. Many characteristics of morphology, cell type, and neuronal circuitry have been elucidated through methods of neuroimaging. Combining this data in a meaningful, standardized, and accessible manner is the scope and goal of the digital brain atlas. Digital brain atlases are used today in neuroscience to characterize the spatial organization of neuronal structures, for planning and guidance during neurosurgery, and as a reference for interpreting other data modalities such as gene expression and connectivity data. The field of digital atlases is extensive and in addition to atlases of the human includes high quality brain atlases of the mouse, rat, rhesus macaque, and other model organisms. Using techniques based on histology, structural and functional magnetic resonance imaging as well as gene expression data, modern digital atlases use probabilistic and multimodal techniques, as well as sophisticated visualization software to form an integrated product. Toward this goal, brain atlases form a common coordinate framework for summarizing, accessing, and organizing this knowledge and will undoubtedly remain a key technology in neuroscience in the future. Since the development of its flagship project of a genome wide image-based atlas of the mouse brain, the Allen Institute for Brain Science has used imaging as a primary data modality for many of its large scale atlas projects. We present an overview of Allen Institute digital atlases in neuroscience, with a focus on the challenges and opportunities for image processing and computation.

  2. Temporal and spatial variations in fly ash quality

    USGS Publications Warehouse

    Hower, J.C.; Trimble, A.S.; Eble, C.F.

    2001-01-01

    Fly ash quality, both as the amount of petrographically distinguishable carbons and in chemistry, varies in both time and space. Temporal variations are a function of a number of variables. Variables can include variations in the coal blend organic petrography, mineralogy, and chemistry; variations in the pulverization of the coal, both as a function of the coal's Hardgrove grindability index and as a function of the maintenance and settings of the pulverizers; and variations in the operating conditions of the boiler, including changes in the pollution control system. Spatial variation, as an instantaneous measure of fly ash characteristics, should not involve changes in the first two sets of variables listed above. Spatial variations are a function of the gas flow within the boiler and ducts, certain flow conditions leading to a tendency for segregation of the less-dense carbons in one portion of the gas stream. Caution must be applied in sampling fly ash. Samples from a single bin, or series of bins, m ay not be representative of the whole fly ash, providing a biased view of the nature of the material. Further, it is generally not possible to be certain about variation until the analysis of the ash is complete. ?? 2001 Elsevier Science B.V. All rights reserved.

  3. Assessment of spatial variation of cesium-137 in small catchments.

    PubMed

    van der Perk, Marcel; Slávik, Ondrej; Fulajtár, Emil

    2002-01-01

    Surface contamination by bomb-derived and Chernobyl-derived 137Cs has been subject to changes due to physical decay and lateral transport of contaminated soil particles, which have resulted in an on-going transfer of radionuclides from terrestrial ecosystems to surface water, river bed sediments, and flood plains. Knowledge of the different sources of spatial variation of 137Cs is particularly essential for estimating 137Cs transfer to fluvial systems and for successfully applying 137Cs as an environmental tracer in soil erosion studies. This study combined a straightforward sediment redistribution model and geostatistical interpolation of point samples of 137Cs activities in soil to distinguish the effects of sediment erosion and deposition from other sources of variation in 137Cs in the small Mochovce catchment in Slovakia. These other sources of variation could then be interpreted. Besides erosion and deposition processes, the initial pattern of 137Cs deposition, floodplain sedimentation, and short-range spatial variation were identified as the major sources of spatial variation of the 137Cs inventory. PMID:12469843

  4. Reducing spatial variation in environmental assessment of marine benthic fauna.

    PubMed

    Leonardsson, Kjell; Blomqvist, Mats; Rosenberg, Rutger

    2016-03-15

    The Benthic Quality Index, BQI, is widely used for benthic quality assessment. Here, we investigated if spatial variation in the BQI can be reduced by accounting for the environmental factors instead of having different boundaries for different salinity regimes between status classes in the EU Water Framework Directive and Marine Strategy Framework Directive. For this purpose we tested salinity, sediment structure, and depth in a regression model to test their contribution to variations in BQI. The spatial variation in BQI was better explained by depth than by salinity or sediment structure. The proposed assessment method uses the residuals from the regression model between BQI and depth. With this method the variance in BQI between samples was reduced by 50% to 75% in the majority of situations. A method to establish the boundary between good and moderate status and how to derive EQR-values according to the WFD is presented. PMID:26856645

  5. Synthesis of small and large scale dynamos

    NASA Astrophysics Data System (ADS)

    Subramanian, Kandaswamy

    Using a closure model for the evolution of magnetic correlations, we uncover an interesting plausible saturated state of the small-scale fluctuation dynamo (SSD) and a novel analogy between quantum mechanical tunnelling and the generation of large-scale fields. Large scale fields develop via the α-effect, but as magnetic helicity can only change on a resistive timescale, the time it takes to organize the field into large scales increases with magnetic Reynolds number. This is very similar to the results which obtain from simulations using the full MHD equations.

  6. The spatial variation of vegetation changes at very coarse scales

    NASA Technical Reports Server (NTRS)

    Townshend, John R. G.; Justice, Christopher O.

    1990-01-01

    Previous analysis (Townshend and Justice 1988) is extended to examine the spatial variations in images of the normalized difference vegetation index (NDVI) of seven areas. These images were derived by subtracting corresponding pixel values from pairs of registered MSS images. The changes depicted by these derived images were analyzed by scale variance analysis for pixel sizes between 4 km and 64 km. It is shown that for some areas substantial changes are detectable at these very coarse scales, although there is less contrast between the areas than at finer spatial resolutions below 1 km. In all the areas the total spatial variability of the images is contributed at a wide variety of spatial scales.

  7. Spatial Variation as a Tool for Inferring Temporal Variation and Diagnosing Types of Mechanisms in Ecosystems

    PubMed Central

    Hammond, Matthew P.; Kolasa, Jurek

    2014-01-01

    Ecological processes, like the rise and fall of populations, leave an imprint of their dynamics as a pattern in space. Mining this spatial record for insight into temporal change underlies many applications, including using spatial snapshots to infer trends in communities, rates of species spread across boundaries, likelihood of chaotic dynamics, and proximity to regime shifts. However, these approaches rely on an inherent but undefined link between spatial and temporal variation. We present a quantitative link between a variable’s spatial and temporal variation based on established variance-partitioning techniques, and test it for predictive and diagnostic applications. A strong link existed between spatial and regional temporal variation (estimated as Coefficients of Variation or CV’s) in 136 variables from three aquatic ecosystems. This association suggests a basis for substituting one for the other, either quantitatively or qualitatively, when long time series are lacking. We further show that weak substitution of temporal for spatial CV results from distortion by specific spatiotemporal patterns (e.g., inter-patch synchrony). Where spatial and temporal CV’s do not match, we pinpoint the spatiotemporal causes of deviation in the dynamics of variables and suggest ways that may control for them. In turn, we demonstrate the use of this framework for describing spatiotemporal patterns in multiple ecosystem variables and attributing them to types of mechanisms. Linking spatial and temporal variability makes quantitative the hitherto inexact practice of space-for-time substitution and may thus point to new opportunities for navigating the complex variation of ecosystems. PMID:24586627

  8. Uncovering Spatial Variation in Acoustic Environments Using Sound Mapping

    PubMed Central

    Job, Jacob R.; Myers, Kyle; Naghshineh, Koorosh; Gill, Sharon A.

    2016-01-01

    Animals select and use habitats based on environmental features relevant to their ecology and behavior. For animals that use acoustic communication, the sound environment itself may be a critical feature, yet acoustic characteristics are not commonly measured when describing habitats and as a result, how habitats vary acoustically over space and time is poorly known. Such considerations are timely, given worldwide increases in anthropogenic noise combined with rapidly accumulating evidence that noise hampers the ability of animals to detect and interpret natural sounds. Here, we used microphone arrays to record the sound environment in three terrestrial habitats (forest, prairie, and urban) under ambient conditions and during experimental noise introductions. We mapped sound pressure levels (SPLs) over spatial scales relevant to diverse taxa to explore spatial variation in acoustic habitats and to evaluate the number of microphones needed within arrays to capture this variation under both ambient and noisy conditions. Even at small spatial scales and over relatively short time spans, SPLs varied considerably, especially in forest and urban habitats, suggesting that quantifying and mapping acoustic features could improve habitat descriptions. Subset maps based on input from 4, 8, 12 and 16 microphones differed slightly (< 2 dBA/pixel) from those based on full arrays of 24 microphones under ambient conditions across habitats. Map differences were more pronounced with noise introductions, particularly in forests; maps made from only 4-microphones differed more (> 4 dBA/pixel) from full maps than the remaining subset maps, but maps with input from eight microphones resulted in smaller differences. Thus, acoustic environments varied over small spatial scales and variation could be mapped with input from 4–8 microphones. Mapping sound in different environments will improve understanding of acoustic environments and allow us to explore the influence of spatial variation

  9. Uncovering Spatial Variation in Acoustic Environments Using Sound Mapping.

    PubMed

    Job, Jacob R; Myers, Kyle; Naghshineh, Koorosh; Gill, Sharon A

    2016-01-01

    Animals select and use habitats based on environmental features relevant to their ecology and behavior. For animals that use acoustic communication, the sound environment itself may be a critical feature, yet acoustic characteristics are not commonly measured when describing habitats and as a result, how habitats vary acoustically over space and time is poorly known. Such considerations are timely, given worldwide increases in anthropogenic noise combined with rapidly accumulating evidence that noise hampers the ability of animals to detect and interpret natural sounds. Here, we used microphone arrays to record the sound environment in three terrestrial habitats (forest, prairie, and urban) under ambient conditions and during experimental noise introductions. We mapped sound pressure levels (SPLs) over spatial scales relevant to diverse taxa to explore spatial variation in acoustic habitats and to evaluate the number of microphones needed within arrays to capture this variation under both ambient and noisy conditions. Even at small spatial scales and over relatively short time spans, SPLs varied considerably, especially in forest and urban habitats, suggesting that quantifying and mapping acoustic features could improve habitat descriptions. Subset maps based on input from 4, 8, 12 and 16 microphones differed slightly (< 2 dBA/pixel) from those based on full arrays of 24 microphones under ambient conditions across habitats. Map differences were more pronounced with noise introductions, particularly in forests; maps made from only 4-microphones differed more (> 4 dBA/pixel) from full maps than the remaining subset maps, but maps with input from eight microphones resulted in smaller differences. Thus, acoustic environments varied over small spatial scales and variation could be mapped with input from 4-8 microphones. Mapping sound in different environments will improve understanding of acoustic environments and allow us to explore the influence of spatial variation

  10. Large-scale regions of antimatter

    SciTech Connect

    Grobov, A. V. Rubin, S. G.

    2015-07-15

    Amodified mechanism of the formation of large-scale antimatter regions is proposed. Antimatter appears owing to fluctuations of a complex scalar field that carries a baryon charge in the inflation era.

  11. Temporal and Spatial Variations in the Twinning Rate in Norway.

    PubMed

    Fellman, Johan

    2016-08-01

    Strong geographical variations have been noted in the twinning rate (TWR). In general, the rate is high among people of African origin, intermediate among Europeans, and low among most Asiatic populations. In Europe, there tends to be a south-north cline, with a progressive increase in the TWR from south to north and a minimum around the Basque provinces. The highest TWRs in Europe have been found among the Nordic populations. Furthermore, within larger populations, small isolated subpopulations have been identified to have extreme, mainly high, TWRs. In the study of the temporal variation of the TWR in Norway, we consider the period from 1900 to 2014. The regional variation of the TWR in Norway is analyzed for the different counties for two periods, 1916-1926 and 1960-1988. Heterogeneity between the regional TWRs in Norway during 1916-1926 was found, but the goodness of fit for the alternative spatial models was only slight. The optimal regression model for the TWR in Norway has the longitude and its square as regressors. According to this model, the spatial variation is distributed in a west-east direction. For 1960-1988, no significant regional variation was observed. One may expect that the environmental and genetic differences between the counties in Norway have disappeared and that the regional TWRs have converged towards a common low level. PMID:27339822

  12. Investigation of spatial variations in collection efficiency of solar cells

    NASA Astrophysics Data System (ADS)

    Hiltner, Jason Fredrick

    2001-11-01

    In an effort to investigate spatial variations in solar cells, an apparatus which is capable of mapping collection efficiency with micron resolution and near- solar intensity has been developed. Local reductions in collection are observed in CdTe- and Cu(In1- xGax)Se2- based devices, and are characterized by measuring the response as a function of cell bias and incident laser intensity. By modeling this data with an equivalent circuit, it is clear that the majority of local variations in the response are due to series resistance variations. Further, direct evidence is given for bandgap variations in CdTe solar cells, which are correlated with high resistance regions in some devices. The bandgap variation is attributed to diffusion of S into CdTe, forming the lower bandgap CdTe1- xSx, during the post-deposition CdCl2 treatment commonly used to improve performance. Investigation of the impact of CdCl2 on a CdTe solar cell indicates that the treatment reduces the number of variations seen with above-bandgap photon energies, but also increases local variations in bandgap. The latter effect has been attributed to non-uniform penetration of CdCl2 to the device interface. Finally, elevated-temperature stress on CdTe devices is shown to preferentially degrade regions which exhibit decreases in bandgap, and hence increased S alloying.

  13. Long-term Spatial and Temporal Variations of Aurora Borealis Events in the Period 1700 - 1905

    NASA Astrophysics Data System (ADS)

    Vázquez, M.; Vaquero, J. M.; Gallego, M. C.

    2014-05-01

    Catalogues and other records of aurora-borealis events were used to study the long-term spatial and temporal variation of these phenomena in the period from 1700 to 1905 in the Northern Hemisphere. For this purpose, geographic and geomagnetic coordinates were assigned to approximately 27 000 auroral events with more than 80 000 observations. They were analyzed separately in three large-scale areas: i) Europe and North Africa, ii) North America, and iii) Asia. There was a clear need to fill some gaps existing in the records so as to have a reliable proxy of solar activity, especially during the 18th century. In order to enhance the long-term variability, an 11-year smoothing window was applied to the data. Variations in the cumulative numbers of auroral events with latitude (in both geographic and geomagnetic coordinates) were used to discriminate between the two main solar sources: coronal mass ejections and high-speed streams from coronal holes. The characteristics of the associated auroras correlate differently with the solar-activity cycle.

  14. Spatial variation buffers temporal fluctuations in early juvenile survival for an endangered Pacific salmon.

    PubMed

    Thorson, James T; Scheuerell, Mark D; Buhle, Eric R; Copeland, Timothy

    2014-01-01

    Spatial, phenotypic and genetic diversity at relatively small scales can buffer species against large-scale processes such as climate change that tend to synchronize populations and increase temporal variability in overall abundance or production. This portfolio effect generally results in improved biological and economic outcomes for managed species. Previous evidence for the portfolio effect in salmonids has arisen from examinations of time series of adult abundance, but we lack evidence of spatial buffering of temporal variability in demographic rates such as survival of juveniles during their first year of life. We therefore use density-dependent population models with multiple random effects to represent synchronous (similar among populations) and asynchronous (different among populations) temporal variability as well as spatial variability in survival. These are fitted to 25 years of survey data for breeding adults and surviving juveniles from 15 demographically distinct populations of Chinook salmon (Oncorhynchus tshawytscha) within a single metapopulation in the Snake River in Idaho, USA. Model selection identifies the most support for the model that included both synchronous and asynchronous temporal variability, in addition to spatial variability. Asynchronous variability (log-SD = 0·55) is approximately equal in magnitude to synchronous temporal variability (log-SD = 0·67), but much lower than spatial variability (log-SD = 1·11). We also show that the pairwise correlation coefficient, a common measure of population synchrony, is approximated by the estimated ratio of shared and total variance, where both approaches yield a synchrony estimate of 0·59. We therefore find evidence for spatial buffering of temporal variability in early juvenile survival, although between-population variability that persists over time is also large. We conclude that spatial variation decreases interannual changes in overall juvenile production, which suggests that

  15. Magnetic Helicity and Large Scale Magnetic Fields: A Primer

    NASA Astrophysics Data System (ADS)

    Blackman, Eric G.

    2015-05-01

    Magnetic fields of laboratory, planetary, stellar, and galactic plasmas commonly exhibit significant order on large temporal or spatial scales compared to the otherwise random motions within the hosting system. Such ordered fields can be measured in the case of planets, stars, and galaxies, or inferred indirectly by the action of their dynamical influence, such as jets. Whether large scale fields are amplified in situ or a remnant from previous stages of an object's history is often debated for objects without a definitive magnetic activity cycle. Magnetic helicity, a measure of twist and linkage of magnetic field lines, is a unifying tool for understanding large scale field evolution for both mechanisms of origin. Its importance stems from its two basic properties: (1) magnetic helicity is typically better conserved than magnetic energy; and (2) the magnetic energy associated with a fixed amount of magnetic helicity is minimized when the system relaxes this helical structure to the largest scale available. Here I discuss how magnetic helicity has come to help us understand the saturation of and sustenance of large scale dynamos, the need for either local or global helicity fluxes to avoid dynamo quenching, and the associated observational consequences. I also discuss how magnetic helicity acts as a hindrance to turbulent diffusion of large scale fields, and thus a helper for fossil remnant large scale field origin models in some contexts. I briefly discuss the connection between large scale fields and accretion disk theory as well. The goal here is to provide a conceptual primer to help the reader efficiently penetrate the literature.

  16. Feedback control of solid oxide fuel cell spatial temperature variation

    NASA Astrophysics Data System (ADS)

    Fardadi, Mahshid; Mueller, Fabian; Jabbari, Faryar

    A high performance feedback controller has been developed to minimize SOFC spatial temperature variation following significant load perturbations. For thermal management, spatial temperature variation along SOFC cannot be avoided. However, results indicate that feedback control can be used to manipulate the fuel cell air flow and inlet fuel cell air temperature to maintain a nearly constant SOFC electrode electrolyte assembly temperature profile. For example temperature variations of less than 5 K are obtained for load perturbations of ±25% from nominal. These results are obtained using a centralized control strategy to regulate a distributed temperature profile and manage actuator interactions. The controller is based on H-infinity synthesis using a physical based dynamic model of a single co-flow SOFC repeat cell. The model of the fuel cell spatial temperature response needed for control synthesis was linearized and reduced from nonlinear model of the fuel cell assembly. A single 11 state feedback linear system tested in the full nonlinear model was found to be effective and stable over a wide fuel cell operating envelope (0.82-0.6 V). Overall, simulation of the advanced controller resulted in small and smooth monotonic temperature response to rapid and large load perturbations. This indicates that future SOFC systems can be designed and controlled to have superb load following characteristic with less than previously expected thermal stresses.

  17. Spatial variation in soil phosphomonoesterase in irrigated and dry farmlands

    NASA Astrophysics Data System (ADS)

    Sinegani, A. A. S.; Hossainpour, A.; Nazarizadeh, F.

    2006-05-01

    Spatial variation in the content of acid and alkaline phosphatase was surveyed on two farmlands. Two adjacent plots, one irrigated and cultivated and the other nonirrigated and cultivated, were marked on a 300-m-long transect with 10-m spacing. Soil samples were collected at the depths of 0-30 and 30-60 cm and were then analyzed for acid and alkaline phosphatase and other soil parameters. The analytical results were then subjected to classical statistical and geostatistical analysis. The results showed that the correlation coefficients of the phosphatase and clay, the silt, the sand, the mean weight diameter, the geometric mean diameter, the equivalent CaCO3, the pH, the electrical conductivity, the organic carbon, the respiration, the Olsen available phosphorus, and the vesicular arbuscular mycorrhizae (VAM) spore numbers of the soils in the transect studied were highly significant. In both layers of the irrigated farmland, the coefficients of the variation of the acid phosphatase were relatively high and the coefficients of the variation of the alkaline phosphatase were relatively low compared to those of the dry farmland. Although the acid and alkaline phosphatase in the topsoil and subsoil of the farmlands exhibited a spatial dependence at the sampled scale, the stability of the spatial structures were markedly low.

  18. Individual skill differences and large-scale environmental learning.

    PubMed

    Fields, Alexa W; Shelton, Amy L

    2006-05-01

    Spatial skills are known to vary widely among normal individuals. This project was designed to address whether these individual differences are differentially related to large-scale environmental learning from route (ground-level) and survey (aerial) perspectives. Participants learned two virtual environments (route and survey) with limited exposure and tested on judgments about relative locations of objects. They also performed a series of spatial and nonspatial component skill tests. With limited learning, performance after route encoding was worse than performance after survey encoding. Furthermore, performance after route and survey encoding appeared to be preferentially linked to perspective and object-based transformations, respectively. Together, the results provide clues to how different skills might be engaged by different individuals for the same goal of learning a large-scale environment. PMID:16719662

  19. Spatial Variation of Soil Type and Soil Moisture in the Regional Atmospheric Modeling System

    SciTech Connect

    Buckley, R.

    2001-06-27

    Soil characteristics (texture and moisture) are typically assumed to be initially constant when performing simulations with the Regional Atmospheric Modeling System (RAMS). Soil texture is spatially homogeneous and time-independent, while soil moisture is often spatially homogeneous initially, but time-dependent. This report discusses the conversion of a global data set of Food and Agriculture Organization (FAO) soil types to RAMS soil texture and the subsequent modifications required in RAMS to ingest this information. Spatial variations in initial soil moisture obtained from the National Center for Environmental Predictions (NCEP) large-scale models are also introduced. Comparisons involving simulations over the southeastern United States for two different time periods, one during warmer, more humid summer conditions, and one during cooler, dryer winter conditions, reveals differences in surface conditions related to increases or decreases in near-surface atmospheric moisture con tent as a result of different soil properties. Three separate simulation types were considered. The base case assumed spatially homogeneous soil texture and initial soil moisture. The second case assumed variable soil texture and constant initial soil moisture, while the third case allowed for both variable soil texture and initial soil moisture. The simulation domain was further divided into four geographically distinct regions. It is concluded there is a more dramatic impact on thermodynamic variables (surface temperature and dewpoint) than on surface winds, and a more pronounced variability in results during the summer period. While no obvious trends in surface winds or dewpoint temperature were found relative to observations covering all regions and times, improvement in surface temperatures in most regions and time periods was generally seen with the incorporation of variable soil texture and initial soil moisture.

  20. Sensitivity technologies for large scale simulation.

    SciTech Connect

    Collis, Samuel Scott; Bartlett, Roscoe Ainsworth; Smith, Thomas Michael; Heinkenschloss, Matthias; Wilcox, Lucas C.; Hill, Judith C.; Ghattas, Omar; Berggren, Martin Olof; Akcelik, Volkan; Ober, Curtis Curry; van Bloemen Waanders, Bart Gustaaf; Keiter, Eric Richard

    2005-01-01

    order approximation of the Euler equations and used as a preconditioner. In comparison to other methods, the AD preconditioner showed better convergence behavior. Our ultimate target is to perform shape optimization and hp adaptivity using adjoint formulations in the Premo compressible fluid flow simulator. A mathematical formulation for mixed-level simulation algorithms has been developed where different physics interact at potentially different spatial resolutions in a single domain. To minimize the implementation effort, explicit solution methods can be considered, however, implicit methods are preferred if computational efficiency is of high priority. We present the use of a partial elimination nonlinear solver technique to solve these mixed level problems and show how these formulation are closely coupled to intrusive optimization approaches and sensitivity analyses. Production codes are typically not designed for sensitivity analysis or large scale optimization. The implementation of our optimization libraries into multiple production simulation codes in which each code has their own linear algebra interface becomes an intractable problem. In an attempt to streamline this task, we have developed a standard interface between the numerical algorithm (such as optimization) and the underlying linear algebra. These interfaces (TSFCore and TSFCoreNonlin) have been adopted by the Trilinos framework and the goal is to promote the use of these interfaces especially with new developments. Finally, an adjoint based a posteriori error estimator has been developed for discontinuous Galerkin discretization of Poisson's equation. The goal is to investigate other ways to leverage the adjoint calculations and we show how the convergence of the forward problem can be improved by adapting the grid using adjoint-based error estimates. Error estimation is usually conducted with continuous adjoints but if discrete adjoints are available it may be possible to reuse the discrete version

  1. Spatial variation in disease resistance: from molecules to metapopulations

    PubMed Central

    Laine, Anna-Liisa; Burdon, Jeremy J.; Dodds, Peter N.; Thrall, Peter H.

    2010-01-01

    Summary Variation in disease resistance is a widespread phenomenon in wild plant-pathogen associations. Here, we review current literature on natural plant-pathogen associations to determine how diversity in disease resistance is distributed at different hierarchical levels – within host individuals, within host populations, among host populations at the metapopulation scale and at larger regional scales. We find diversity in resistance across all spatial scales examined. Furthermore, variability seems to be the best counter-defence of plants against their rapidly evolving pathogens. We find that higher diversity of resistance phenotypes also results in higher levels of resistance at the population level. Overall, we find that wild plant populations are more likely to be susceptible than resistant to their pathogens. However, the degree of resistance differs strikingly depending on the origin of the pathogen strains used in experimental inoculation studies. Plant populations are on average 16% more resistant to allopatric pathogen strains than they are to strains that occur within the same population (48 % vs. 32 % respectively). Pathogen dispersal mode affects levels of resistance in natural plant populations with lowest levels detected for hosts of airborne pathogens and highest for waterborne pathogens. Detailed analysis of two model systems, Linum marginale infected by Melampsora lini, and Plantago lanceolata infected by Podosphaera plantaginis, show that the amount of variation in disease resistance declines towards higher spatial scales as we move from individual hosts to metapopulations, but evaluation of multiple spatial scales is needed to fully capture the structure of disease resistance. Synthesis: Variation in disease resistance is ubiquitous in wild plant-pathogen associations. While the debate over whether the resistance structure of plant populations is determined by pathogen-imposed selection versus non-adaptive processes remains unresolved, we do

  2. Spatial variations in Achilles tendon shear wave speed

    PubMed Central

    DeWall, Ryan J.; Slane, Laura C.; Lee, Kenneth S.; Thelen, Darryl G.

    2014-01-01

    Supersonic shear imaging (SSI) is an ultrasound imaging modality that can provide insight into tissue mechanics by measuring shear wave propagation speed, a property that depends on tissue elasticity. SSI has previously been used to characterize the increase in Achilles tendon shear wave speed that occurs with loading, an effect attributable to the strain-stiffening behavior of the tissue. However, little is known about how shear wave speed varies spatially, which is important, given the anatomical variation that occurs between the calcaneus insertion and the gastrocnemius musculotendon junction. The purpose of this study was to investigate spatial variations in shear wave speed along medial and lateral paths of the Achilles tendon for three different ankle postures: resting ankle angle (R, i.e. neutral), plantarflexed (P; R − 15 deg), and dorsiflexed (D; R + 15 deg). We observed significant spatial and posture variations in tendon shear wave speed in ten healthy young adults. Shear wave speeds in the Achilles free tendon averaged 12 ± 1.2 m/s in a resting position, but decreased to 7.2 ± 1.8 m/s with passive plantarflexion. Distal tendon shear wave speeds often reached the maximum tracking limit (16.3 m/s) of the system when the ankle was in the passively dorsiflexed posture (+15 deg from R). At a fixed posture, shear wave speeds decreased significantly from the free tendon to the gastrocnemius musculotendon junction, with slightly higher speeds measured on the medial side than on the lateral side. Shear wave speeds were only weakly correlated with the thickness and depth of the tendon, suggesting that the distal-to-proximal variations may reflect greater compliance in the aponeurosis relative to the free tendon. The results highlight the importance of considering both limb posture and transducer positioning when using SSI for biomechanical and clinical assessments of the Achilles tendon. PMID:24933528

  3. Effect of Large-Scale Bathymetry on Internal Wave Structure in Lakes

    NASA Astrophysics Data System (ADS)

    Fricker, Paul D.; Nepf, Heidi M.

    1998-11-01

    Internal wave structure can be strongly influenced by large-scale bathymetry. In particular, analytic solutions suggest that seiche motion is amplified in shallow regions, so that seiche-induced mixing should be augmented over shelf bathymetry. A combination of field and numerical studies is used to examine the dynamic significance of simple bathymetric variation as well the potential impact on bed-source contamination. Internal wave eigensolutions are evaluated numerically for a model bathmetry which includes a shallow ledge and compared to simpler solutions such as the box-model lake. The predicted spatial structure of isotherm displacement predicted for a V1H1 mode is compared with actual thermistor chain data, collected in the Upper Mystic Lake, near Boston, MA. The comparison confirms the predicted modal structure, specifically including the amplification of seiche motions on the shelf. We consider how large-scale bathymetry of the lake may focus internal wave energy and create local 'hot spots' where the vertical flux of contaminant is accelerated. Because the spatial heterogeneity of internal wave motions can influence spatial distribution and redistribution of contaminants, these motions have important implications for long-term fate of watershed contamination and the interpretation of historic contamination through sediment records.

  4. Survey on large scale system control methods

    NASA Technical Reports Server (NTRS)

    Mercadal, Mathieu

    1987-01-01

    The problem inherent to large scale systems such as power network, communication network and economic or ecological systems were studied. The increase in size and flexibility of future spacecraft has put those dynamical systems into the category of large scale systems, and tools specific to the class of large systems are being sought to design control systems that can guarantee more stability and better performance. Among several survey papers, reference was found to a thorough investigation on decentralized control methods. Especially helpful was the classification made of the different existing approaches to deal with large scale systems. A very similar classification is used, even though the papers surveyed are somehow different from the ones reviewed in other papers. Special attention is brought to the applicability of the existing methods to controlling large mechanical systems like large space structures. Some recent developments are added to this survey.

  5. Large-scale inhomogeneities and galaxy statistics

    NASA Technical Reports Server (NTRS)

    Schaeffer, R.; Silk, J.

    1984-01-01

    The density fluctuations associated with the formation of large-scale cosmic pancake-like and filamentary structures are evaluated using the Zel'dovich approximation for the evolution of nonlinear inhomogeneities in the expanding universe. It is shown that the large-scale nonlinear density fluctuations in the galaxy distribution due to pancakes modify the standard scale-invariant correlation function xi(r) at scales comparable to the coherence length of adiabatic fluctuations. The typical contribution of pancakes and filaments to the J3 integral, and more generally to the moments of galaxy counts in a volume of approximately (15-40 per h Mpc)exp 3, provides a statistical test for the existence of large scale inhomogeneities. An application to several recent three dimensional data sets shows that despite large observational uncertainties over the relevant scales characteristic features may be present that can be attributed to pancakes in most, but not all, of the various galaxy samples.

  6. Response of Tradewind Cumuli to Large-Scale Processes.

    NASA Astrophysics Data System (ADS)

    Soong, S.-T.; Ogura, Y.

    1980-09-01

    variation in height and intensity of the trade-wind inversion. This may indicate that cumulus clouds respond quickly to the large-scale forcing and adjust their own transport properties to maintain the observed large-scale thermodynamic fields whose variation has a much longer time scale. Sensitivity tests on varying sea surface temperature indicate that a ±1°C change in the sea surface temperature does not change the height of the inversion significantly during a 6 h simulation period. Another simulation shows that a tradewind inversion can develop rapidly from an initial sounding without an inversion if the large-scale downward motion is fairly large.

  7. Spatial and temporal variation of body size among early Homo.

    PubMed

    Will, Manuel; Stock, Jay T

    2015-05-01

    The estimation of body size among the earliest members of the genus Homo (2.4-1.5Myr [millions of years ago]) is central to interpretations of their biology. It is widely accepted that Homo ergaster possessed increased body size compared with Homo habilis and Homo rudolfensis, and that this may have been a factor involved with the dispersal of Homo out of Africa. The study of taxonomic differences in body size, however, is problematic. Postcranial remains are rarely associated with craniodental fossils, and taxonomic attributions frequently rest upon the size of skeletal elements. Previous body size estimates have been based upon well-preserved specimens with a more reliable species assessment. Since these samples are small (n < 5) and disparate in space and time, little is known about geographical and chronological variation in body size within early Homo. We investigate temporal and spatial variation in body size among fossils of early Homo using a 'taxon-free' approach, considering evidence for size variation from isolated and fragmentary postcranial remains (n = 39). To render the size of disparate fossil elements comparable, we derived new regression equations for common parameters of body size from a globally representative sample of hunter-gatherers and applied them to available postcranial measurements from the fossils. The results demonstrate chronological and spatial variation but no simple temporal or geographical trends for the evolution of body size among early Homo. Pronounced body size increases within Africa take place only after hominin populations were established at Dmanisi, suggesting that migrations into Eurasia were not contingent on larger body sizes. The primary evidence for these marked changes among early Homo is based upon material from Koobi Fora after 1.7Myr, indicating regional size variation. The significant body size differences between specimens from Koobi Fora and Olduvai support the cranial evidence for at least two co

  8. Genetic mapping of variation in spatial learning in the mouse.

    PubMed

    Steinberger, Daniela; Reynolds, David S; Ferris, Pushpindar; Lincoln, Rachael; Datta, Susmita; Stanley, Joanna; Paterson, Andrea; Dawson, Gerard R; Flint, Jonathan

    2003-03-15

    Inbred strains of mice are known to differ in their performance in the Morris water maze task, a test of spatial discrimination and place navigation in rodents, but the genetic basis of individual variation in spatial learning is unknown. We have mapped genetic effects that contribute to the difference between two strains, DBA/2 and C57BL6/J, using an F2 intercross and methods to detect quantitative trait loci (QTL). We found two QTL, one on chromosome 4 and one on chromosome 12, that influence behavior in the probe trial of the water maze (genome-wide significance p = 0.017 and 0.015, respectively). By including tests of avoidance conditioning and behavior in a novel environment, we show that the QTL on chromosomes 4 and 12 specifically influence variation in spatial learning. QTL that influence differences in fearful behavior (on chromosomes 1, 3, 7, 15, and 19) operate while mice are trained in the water maze apparatus. PMID:12657702

  9. Actinide ions for testing the spatial α -variation hypothesis

    NASA Astrophysics Data System (ADS)

    Dzuba, V. A.; Safronova, M. S.; Safronova, U. I.; Flambaum, V. V.

    2015-12-01

    Testing the spatial variation of the fine-structure constant α indicated by Webb et al. [J. K. Webb, J. A. King, M. T. Murphy, V. V. Flambaum, R. F. Carswell, and M. B. Bainbridge, Phys. Rev. Lett. 107, 191101 (2011), 10.1103/PhysRevLett.107.191101] with terrestrial laboratory atomic measurements requires at least α ˙/α ˜10-19yr-1 sensitivity. We conduct a systematic search of atomic systems for such a test that have all features of the best optical clock transitions leading to the possibility of the frequency measurements with fractional accuracy on the level of 10-18 or better and have a factor of 100 extra enhancement of α variation in comparison to experimental frequency ratio measurement accuracy. We identify the pair of actinide Cf15 + and Es16 + ions as the best system for a test of spatial α -variation hypothesis as it satisfies both of these requirements and has sufficiently simple electronic structure to allow for high-precision predictions of all atomic properties required for rapid experimental progress.

  10. Estimating spatial and temporal components of variation in count data using negative binomial mixed models

    USGS Publications Warehouse

    Irwin, Brian J.; Wagner, Tyler; Bence, James R.; Kepler, Megan V.; Liu, Weihai; Hayes, Daniel B.

    2013-01-01

    Partitioning total variability into its component temporal and spatial sources is a powerful way to better understand time series and elucidate trends. The data available for such analyses of fish and other populations are usually nonnegative integer counts of the number of organisms, often dominated by many low values with few observations of relatively high abundance. These characteristics are not well approximated by the Gaussian distribution. We present a detailed description of a negative binomial mixed-model framework that can be used to model count data and quantify temporal and spatial variability. We applied these models to data from four fishery-independent surveys of Walleyes Sander vitreus across the Great Lakes basin. Specifically, we fitted models to gill-net catches from Wisconsin waters of Lake Superior; Oneida Lake, New York; Saginaw Bay in Lake Huron, Michigan; and Ohio waters of Lake Erie. These long-term monitoring surveys varied in overall sampling intensity, the total catch of Walleyes, and the proportion of zero catches. Parameter estimation included the negative binomial scaling parameter, and we quantified the random effects as the variations among gill-net sampling sites, the variations among sampled years, and site × year interactions. This framework (i.e., the application of a mixed model appropriate for count data in a variance-partitioning context) represents a flexible approach that has implications for monitoring programs (e.g., trend detection) and for examining the potential of individual variance components to serve as response metrics to large-scale anthropogenic perturbations or ecological changes.

  11. Management of large-scale technology

    NASA Technical Reports Server (NTRS)

    Levine, A.

    1985-01-01

    Two major themes are addressed in this assessment of the management of large-scale NASA programs: (1) how a high technology agency was a decade marked by a rapid expansion of funds and manpower in the first half and almost as rapid contraction in the second; and (2) how NASA combined central planning and control with decentralized project execution.

  12. A Large Scale Computer Terminal Output Controller.

    ERIC Educational Resources Information Center

    Tucker, Paul Thomas

    This paper describes the design and implementation of a large scale computer terminal output controller which supervises the transfer of information from a Control Data 6400 Computer to a PLATO IV data network. It discusses the cost considerations leading to the selection of educational television channels rather than telephone lines for…

  13. Large Scale Commodity Clusters for Lattice QCD

    SciTech Connect

    A. Pochinsky; W. Akers; R. Brower; J. Chen; P. Dreher; R. Edwards; S. Gottlieb; D. Holmgren; P. Mackenzie; J. Negele; D. Richards; J. Simone; W. Watson

    2002-06-01

    We describe the construction of large scale clusters for lattice QCD computing being developed under the umbrella of the U.S. DoE SciDAC initiative. We discuss the study of floating point and network performance that drove the design of the cluster, and present our plans for future multi-Terascale facilities.

  14. Evaluating Large-Scale Interactive Radio Programmes

    ERIC Educational Resources Information Center

    Potter, Charles; Naidoo, Gordon

    2009-01-01

    This article focuses on the challenges involved in conducting evaluations of interactive radio programmes in South Africa with large numbers of schools, teachers, and learners. It focuses on the role such large-scale evaluation has played during the South African radio learning programme's development stage, as well as during its subsequent…

  15. ARPACK: Solving large scale eigenvalue problems

    NASA Astrophysics Data System (ADS)

    Lehoucq, Rich; Maschhoff, Kristi; Sorensen, Danny; Yang, Chao

    2013-11-01

    ARPACK is a collection of Fortran77 subroutines designed to solve large scale eigenvalue problems. The package is designed to compute a few eigenvalues and corresponding eigenvectors of a general n by n matrix A. It is most appropriate for large sparse or structured matrices A where structured means that a matrix-vector product w

  16. Large-scale CFB combustion demonstration project

    SciTech Connect

    Nielsen, P.T.; Hebb, J.L.; Aquino, R.

    1998-07-01

    The Jacksonville Electric Authority's large-scale CFB demonstration project is described. Given the early stage of project development, the paper focuses on the project organizational structure, its role within the Department of Energy's Clean Coal Technology Demonstration Program, and the projected environmental performance. A description of the CFB combustion process in included.

  17. Large-scale CFB combustion demonstration project

    SciTech Connect

    Nielsen, P.T.; Hebb, J.L.; Aquino, R.

    1998-04-01

    The Jacksonville Electric Authority`s large-scale CFB demonstration project is described. Given the early stage of project development, the paper focuses on the project organizational structure, its role within the Department of Energy`s Clean Coal Technology Demonstration Program, and the projected environmental performance. A description of the CFB combustion process is included.

  18. Spatial patterns of variation due to natural selection in humans

    PubMed Central

    Novembre, John; Di Rienzo, Anna

    2013-01-01

    Empowered by technology and sampling efforts designed to facilitate genome-wide association mapping, human geneticists are now studying the geography of genetic variation with unprecedented detail. With high genomic coverage and geographic resolution, these studies are identifying loci with spatial signatures of selection, such as extreme levels of differentiation and correlations with environmental variables. Collectively, patterns at these loci are beginning to provide novel insights into the process of human adaptation. Here we review the challenges of these studies and emerging results, including how human population structure has influenced the response to novel selective pressures. PMID:19823195

  19. Spatial and temporal variations of persistent organic pollutants impacted by episodic sediment resuspension in southern Lake Michigan

    PubMed Central

    Miller, Sondra M.; Hornbuckle, Keri C.

    2014-01-01

    The impacts of large-scale, episodic sediment resuspension on the cycling of polychlorinated biphenyl congeners (PCBs) were examined using a spatially coordinated air and water sampling strategy conducted in southern Lake Michigan in the late winters of 1998, 1999, and 2000. We found no significant temporal changes in gas phase, dissolved phase, or suspended sediment PCB concentrations despite large-scale seasonal storms occurring before and after sampling campaigns. Only gas phase and suspended sediment PCBs varied spatially. Higher total suspended material (TSM) concentrations and fraction organic carbon (foc) were measured at sampling stations located in the near-shore region of southern Lake Michigan than at open-water sampling stations. Gas phase concentrations (ΣPCBg) were higher in the west (0.436 ± 0.200 ng/m3, n = 11) and south (0.408 ± 0.286 ng/m3, n = 5) than the east (0.214 ± 0.082 ng/m3, n = 10) and central (0.253 ± 0.145 ng/m3, n = 8) regions of southern Lake Michigan. Dissolved phase concentrations (ΣPCBd) averaged 0.18 ± 0.024 ng/L (n = 52); suspended sediment concentrations (ΣPCBs) accounted for between 4% and 72% (23 ± 4%, n = 52) of the total ΣPCB concentrations (ΣPCBT = ΣPCBd + ΣPCBs). Despite no consistent temporal variations in both dissolved phase or suspended sediment ΣPCB concentrations, there were temporal and spatial variations in the distribution shift between phases that can be linked to sediment resuspension, not a state of equilibrium. Specifically, our analysis suggests sediment resuspension results in preferential sorption of heavier, more chlorinated PCB congeners. PMID:25309030

  20. Errors on interrupter tasks presented during spatial and verbal working memory performance are linearly linked to large-scale functional network connectivity in high temporal resolution resting state fMRI.

    PubMed

    Magnuson, Matthew Evan; Thompson, Garth John; Schwarb, Hillary; Pan, Wen-Ju; McKinley, Andy; Schumacher, Eric H; Keilholz, Shella Dawn

    2015-12-01

    The brain is organized into networks composed of spatially separated anatomical regions exhibiting coherent functional activity over time. Two of these networks (the default mode network, DMN, and the task positive network, TPN) have been implicated in the performance of a number of cognitive tasks. To directly examine the stable relationship between network connectivity and behavioral performance, high temporal resolution functional magnetic resonance imaging (fMRI) data were collected during the resting state, and behavioral data were collected from 15 subjects on different days, exploring verbal working memory, spatial working memory, and fluid intelligence. Sustained attention performance was also evaluated in a task interleaved between resting state scans. Functional connectivity within and between the DMN and TPN was related to performance on these tasks. Decreased TPN resting state connectivity was found to significantly correlate with fewer errors on an interrupter task presented during a spatial working memory paradigm and decreased DMN/TPN anti-correlation was significantly correlated with fewer errors on an interrupter task presented during a verbal working memory paradigm. A trend for increased DMN resting state connectivity to correlate to measures of fluid intelligence was also observed. These results provide additional evidence of the relationship between resting state networks and behavioral performance, and show that such results can be observed with high temporal resolution fMRI. Because cognitive scores and functional connectivity were collected on nonconsecutive days, these results highlight the stability of functional connectivity/cognitive performance coupling. PMID:25563228

  1. Links between small-scale dynamics and large-scale averages and its implication to large-scale hydrology

    NASA Astrophysics Data System (ADS)

    Gong, L.

    2012-04-01

    pixels that could be used to represent the temporal dynamic of a large spatial domain. The derived points or pixels allow a decomposition of the average climate dynamic to a number of patterns of the internal variations and change signals. The coupling of sub-sets of climate input to a set of hydrological response units maintains the non-linear nature of the hydrological system. The possibility that the behavior of a large river basin could be studied from a small sub-set of the basin area, indicates that model setup, calibration and evaluation are not necessarily tied with downstream gauges. Instead, local observations could be used to setup and evaluate large-scale models. This work could potentially open up possibilities for better setting up and evaluate large-scale hydrological models, and study the climate-hydrology interaction with limited data. In the same time, the fact that multiple sets of points or pixels could equally well represent the dynamic of a large domain agreed with the equifinality theory: there exist multiple realisms of different climate-hydrology setttings that could lead to same average behavior. The difference among the multiple sets represents the inherent heterogeneity of the domain. This could indicate new ways to bracket uncertainty for current and future hydrological simulations.

  2. Preparing Students with Learning Disabilities for Large-Scale Writing Assessments

    ERIC Educational Resources Information Center

    Olinghouse, Natalie G.; Colwell, Ryan P.

    2013-01-01

    This article provides recommendations for teachers to better prepare 3rd through 12th grade students with learning disabilities for large-scale writing assessments. The variation across large-scale writing assessments and the multiple needs of struggling writers indicate the need for test preparation to be embedded within a comprehensive,…

  3. Turbulent large-scale structure effects on wake meandering

    NASA Astrophysics Data System (ADS)

    Muller, Y.-A.; Masson, C.; Aubrun, S.

    2015-06-01

    This work studies effects of large-scale turbulent structures on wake meandering using Large Eddy Simulations (LES) over an actuator disk. Other potential source of wake meandering such as the instablility mechanisms associated with tip vortices are not treated in this study. A crucial element of the efficient, pragmatic and successful simulations of large-scale turbulent structures in Atmospheric Boundary Layer (ABL) is the generation of the stochastic turbulent atmospheric flow. This is an essential capability since one source of wake meandering is these large - larger than the turbine diameter - turbulent structures. The unsteady wind turbine wake in ABL is simulated using a combination of LES and actuator disk approaches. In order to dedicate the large majority of the available computing power in the wake, the ABL ground region of the flow is not part of the computational domain. Instead, mixed Dirichlet/Neumann boundary conditions are applied at all the computational surfaces except at the outlet. Prescribed values for Dirichlet contribution of these boundary conditions are provided by a stochastic turbulent wind generator. This allows to simulate large-scale turbulent structures - larger than the computational domain - leading to an efficient simulation technique of wake meandering. Since the stochastic wind generator includes shear, the turbulence production is included in the analysis without the necessity of resolving the flow near the ground. The classical Smagorinsky sub-grid model is used. The resulting numerical methodology has been implemented in OpenFOAM. Comparisons with experimental measurements in porous-disk wakes have been undertaken, and the agreements are good. While temporal resolution in experimental measurements is high, the spatial resolution is often too low. LES numerical results provide a more complete spatial description of the flow. They tend to demonstrate that inflow low frequency content - or large- scale turbulent structures - is

  4. Multitree Algorithms for Large-Scale Astrostatistics

    NASA Astrophysics Data System (ADS)

    March, William B.; Ozakin, Arkadas; Lee, Dongryeol; Riegel, Ryan; Gray, Alexander G.

    2012-03-01

    this number every week, resulting in billions of objects. At such scales, even linear-time analysis operations present challenges, particularly since statistical analyses are inherently interactive processes, requiring that computations complete within some reasonable human attention span. The quadratic (or worse) runtimes of straightforward implementations become quickly unbearable. Examples of applications. These analysis subroutines occur ubiquitously in astrostatistical work. We list just a few examples. The need to cross-match objects across different catalogs has led to various algorithms, which at some point perform an AllNN computation. 2-point and higher-order spatial correlations for the basis of spatial statistics, and are utilized in astronomy to compare the spatial structures of two datasets, such as an observed sample and a theoretical sample, for example, forming the basis for two-sample hypothesis testing. Friends-of-friends clustering is often used to identify halos in data from astrophysical simulations. Minimum spanning tree properties have also been proposed as statistics of large-scale structure. Comparison of the distributions of different kinds of objects requires accurate density estimation, for which KDE is the overall statistical method of choice. The prediction of redshifts from optical data requires accurate regression, for which kernel regression is a powerful method. The identification of objects of various types in astronomy, such as stars versus galaxies, requires accurate classification, for which KDA is a powerful method. Overview. In this chapter, we will briefly sketch the main ideas behind recent fast algorithms which achieve, for example, linear runtimes for pairwise-distance problems, or similarly dramatic reductions in computational growth. In some cases, the runtime orders for these algorithms are mathematically provable statements, while in others we have only conjectures backed by experimental observations for the time being

  5. Spatial and temporal variations in residential housing prices in Beijing

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Lv, Meng; Yin, Zhongdong

    2009-10-01

    During the past 10 years, the real estate industry in Beijing has been manifesting a strongly growing trend. Researching on the distribution of house prices and their tendencies is helpful to grasp and predict the development of the real estate industry and could be used as reference to city planning. 120 records of housing price data in 2005 to 2006 and open prices in 38 developing projects from the first quarter of 2002 to the second quarter of 2008 were used in this study to analyze the spatial and temporal variations of house price with geostatistical methods and nonlinear regression. Results show that there was a very strong autocorrelation among the house prices in Beijing within the range of about 11 km in 2005 to 2006, which can be well fitted with the spherical model. The isogram of the house prices formed a group of homocentric ellipses, with their long axis extending NW-SE, and the house prices decreased from the center to the periphery. The spatial pattern of house prices in Beijing changed obviously from 2003 to 2006. Although both the spatial patterns for the two periods were homocentric ellipses, the shapes of the ellipses and the directions of the axes changed greatly. And there were more imbalances in 2005 to 2006. The house prices in the Huilongguan-Qinghe residential zone, an example of the typical real estate industry in Beijing, kept growing from 2002 to 2008 and could be fitted with exponential growth model.

  6. Time-of-day variation of visuo-spatial attention.

    PubMed

    Fimm, Bruno; Brand, Tanja; Spijkers, Will

    2016-05-01

    Time-of-day variation of visuo-spatial attention in relation to body temperature and subjective arousal was assessed. At five different times of day, alertness, covert, and overt orienting of attention were assessed in fifteen healthy subjects. Based on previous studies reporting a tight coupling of alerting and orienting the present study investigates potential attentional asymmetries induced by diurnal variations of arousal. Both covert and overt orienting of attention improved in the course of the day. However, no asymmetries between left and right visual hemifields could be detected. Covert orienting additionally covaried with body temperature, indicating a quite close relation between the attentional arousal and orienting system. Conversely, overt orienting only improved due to repeated testing but did not correlate with body temperature suggesting a partial independence of both modes of attentional orienting. It can be assumed that due to limited diurnal variations of arousal in the participants and practice effects caused by repeated testing, no attentional asymmetries could be provoked. PMID:26248950

  7. Sea surface temperature and large-scale circulation influences on tropical greenhouse effect and cloud radiative forcing

    SciTech Connect

    Bony, S.; Lau, K.M.; Sud, Y.C.

    1997-08-01

    Two independent sets of meteorological reanalyses are used to investigate relationships between the tropical sea surface temperature (SST) and the large-scale vertical motion of the atmosphere for spatial and seasonal variations, as well as for El Nino/La Nina episodes of 1987-88. Supergreenhouse effect (SGE) situations are found to be linked to the occurrence of enhance large-scale rising motion associated with increasing SST. In regions where the large-scale atmospheric motion is largely decoupled from the local SST due to internal or remote forcings, the SGE occurrence is weak. On seasonal and interannual timescales, such regions are found mainly over equatorial regions of the Indian Ocean and western Pacific, especially for SSTs exceeding 29.5{degrees}C. In these regions, the activation of feedback processes that regulate the ocean temperature is thus likely to be more related to the large-scale remote processes, such as those that govern the monsoon circulations and the low-frequency variability of the atmosphere, than to the local SST change. The relationships among SST, clouds, and cloud radiative forcing inferred from satellite observations are also investigated. 57 refs., 17 figs., 2 tabs.

  8. Fractals and cosmological large-scale structure

    NASA Technical Reports Server (NTRS)

    Luo, Xiaochun; Schramm, David N.

    1992-01-01

    Observations of galaxy-galaxy and cluster-cluster correlations as well as other large-scale structure can be fit with a 'limited' fractal with dimension D of about 1.2. This is not a 'pure' fractal out to the horizon: the distribution shifts from power law to random behavior at some large scale. If the observed patterns and structures are formed through an aggregation growth process, the fractal dimension D can serve as an interesting constraint on the properties of the stochastic motion responsible for limiting the fractal structure. In particular, it is found that the observed fractal should have grown from two-dimensional sheetlike objects such as pancakes, domain walls, or string wakes. This result is generic and does not depend on the details of the growth process.

  9. Condition Monitoring of Large-Scale Facilities

    NASA Technical Reports Server (NTRS)

    Hall, David L.

    1999-01-01

    This document provides a summary of the research conducted for the NASA Ames Research Center under grant NAG2-1182 (Condition-Based Monitoring of Large-Scale Facilities). The information includes copies of view graphs presented at NASA Ames in the final Workshop (held during December of 1998), as well as a copy of a technical report provided to the COTR (Dr. Anne Patterson-Hine) subsequent to the workshop. The material describes the experimental design, collection of data, and analysis results associated with monitoring the health of large-scale facilities. In addition to this material, a copy of the Pennsylvania State University Applied Research Laboratory data fusion visual programming tool kit was also provided to NASA Ames researchers.

  10. Interannual Variability of Heat Wave in South Korea and theirs Connection with Large-Scale Atmospheric Circulation Pattern

    NASA Astrophysics Data System (ADS)

    Lee, Woo-Seop; Lee, Myong-In

    2016-04-01

    This study investigates the interannual variation of heat wave frequency (HWF) in South Korea during the past 42 years (1973-2014) and examines its connection with large-scale atmospheric circulation changes. Korean heat waves tend to develop most frequently in late summer during July and August. The leading Empirical Orthogonal Function (EOF) accounting for 50% of the total variance shows a mono-signed pattern over South Korea, suggesting that the dominant mechanisms responsible for the heat wave are linked in a spatial scale much larger than the nation. It also exhibits a regional variation with more occurrences in the southeastern inland area. The regression of the leading principal component (PC) time series of HWF with large-scale atmospheric circulation identifies a north-south dipole pattern between the South China Sea and Northeast Asia. When this large-scale circulation mode facilitates deep convection in South China Sea, it tends to weaken moisture transport from the South China Sea to Northeast Asia. Enhanced deep convection in the South China Sea triggers a source of Rossby wave train along southerly wind that generates positive geopotential height anomalies around Korea. The anomalous high pressure pattern is accompanied by large-scale subsidence in Korea, thereby providing a favorable condition for extreme hot and dry days in Korea. This study highlights that there is a decadal change of the relationship between Korean heat waves and large-scale atmospheric circulation patterns. The tropical forcing tends to be weakened in the recent decade, with more influences from the Arctic variability from the mid-1990s.