Science.gov

Sample records for access spatial methods

  1. Evaluating Michigan's community hospital access: spatial methods for decision support

    PubMed Central

    Messina, Joseph P; Shortridge, Ashton M; Groop, Richard E; Varnakovida, Pariwate; Finn, Mark J

    2006-01-01

    Background Community hospital placement is dictated by a diverse set of geographical factors and historical contingency. In the summer of 2004, a multi-organizational committee headed by the State of Michigan's Department of Community Health approached the authors of this paper with questions about how spatial analyses might be employed to develop a revised community hospital approval procedure. Three objectives were set. First, the committee needed visualizations of both the spatial pattern of Michigan's population and its 139 community hospitals. Second, the committee required a clear, defensible assessment methodology to quantify access to existing hospitals statewide, taking into account factors such as distance to nearest hospital and road network density to estimate travel time. Third, the committee wanted to contrast the spatial distribution of existing community hospitals with a theoretical configuration that best met statewide demand. This paper presents our efforts to first describe the distribution of Michigan's current community hospital pattern and its people, and second, develop two models, access-based and demand-based, to identify areas with inadequate access to existing hospitals. Results Using the product from the access-based model and contiguity and population criteria, two areas were identified as being "under-served." The lower area, located north/northeast of Detroit, contained the greater total land area and population of the two areas. The upper area was centered north of Grand Rapids. A demand-based model was applied to evaluate the existing facility arrangement by allocating daily bed demand in each ZIP code to the closest facility. We found 1,887 beds per day were demanded by ZIP centroids more than 16.1 kilometers from the nearest existing hospital. This represented 12.7% of the average statewide daily bed demand. If a 32.3 kilometer radius was employed, unmet demand dropped to 160 beds per day (1.1%). Conclusion Both modeling

  2. Spatial Access Priority Mapping (SAPM) with Fishers: A Quantitative GIS Method for Participatory Planning

    PubMed Central

    Yates, Katherine L.; Schoeman, David S.

    2013-01-01

    Spatial management tools, such as marine spatial planning and marine protected areas, are playing an increasingly important role in attempts to improve marine management and accommodate conflicting needs. Robust data are needed to inform decisions among different planning options, and early inclusion of stakeholder involvement is widely regarded as vital for success. One of the biggest stakeholder groups, and the most likely to be adversely impacted by spatial restrictions, is the fishing community. In order to take their priorities into account, planners need to understand spatial variation in their perceived value of the sea. Here a readily accessible, novel method for quantitatively mapping fishers’ spatial access priorities is presented. Spatial access priority mapping, or SAPM, uses only basic functions of standard spreadsheet and GIS software. Unlike the use of remote-sensing data, SAPM actively engages fishers in participatory mapping, documenting rather than inferring their priorities. By so doing, SAPM also facilitates the gathering of other useful data, such as local ecological knowledge. The method was tested and validated in Northern Ireland, where over 100 fishers participated in a semi-structured questionnaire and mapping exercise. The response rate was excellent, 97%, demonstrating fishers’ willingness to be involved. The resultant maps are easily accessible and instantly informative, providing a very clear visual indication of which areas are most important for the fishers. The maps also provide quantitative data, which can be used to analyse the relative impact of different management options on the fishing industry and can be incorporated into planning software, such as MARXAN, to ensure that conservation goals can be met at minimum negative impact to the industry. This research shows how spatial access priority mapping can facilitate the early engagement of fishers and the ready incorporation of their priorities into the decision

  3. Spatial access priority mapping (SAPM) with fishers: a quantitative GIS method for participatory planning.

    PubMed

    Yates, Katherine L; Schoeman, David S

    2013-01-01

    Spatial management tools, such as marine spatial planning and marine protected areas, are playing an increasingly important role in attempts to improve marine management and accommodate conflicting needs. Robust data are needed to inform decisions among different planning options, and early inclusion of stakeholder involvement is widely regarded as vital for success. One of the biggest stakeholder groups, and the most likely to be adversely impacted by spatial restrictions, is the fishing community. In order to take their priorities into account, planners need to understand spatial variation in their perceived value of the sea. Here a readily accessible, novel method for quantitatively mapping fishers' spatial access priorities is presented. Spatial access priority mapping, or SAPM, uses only basic functions of standard spreadsheet and GIS software. Unlike the use of remote-sensing data, SAPM actively engages fishers in participatory mapping, documenting rather than inferring their priorities. By so doing, SAPM also facilitates the gathering of other useful data, such as local ecological knowledge. The method was tested and validated in Northern Ireland, where over 100 fishers participated in a semi-structured questionnaire and mapping exercise. The response rate was excellent, 97%, demonstrating fishers' willingness to be involved. The resultant maps are easily accessible and instantly informative, providing a very clear visual indication of which areas are most important for the fishers. The maps also provide quantitative data, which can be used to analyse the relative impact of different management options on the fishing industry and can be incorporated into planning software, such as MARXAN, to ensure that conservation goals can be met at minimum negative impact to the industry. This research shows how spatial access priority mapping can facilitate the early engagement of fishers and the ready incorporation of their priorities into the decision-making process

  4. Finding Food Deserts: A Comparison of Methods Measuring Spatial Access to Food Stores.

    PubMed

    Jaskiewicz, Lara; Block, Daniel; Chavez, Noel

    2016-05-01

    Public health research has increasingly focused on how access to resources affects health behaviors. Mapping environmental factors, such as distance to a supermarket, can identify intervention points toward improving food access in low-income and minority communities. However, the existing literature provides little guidance on choosing the most appropriate measures of spatial access. This study compared the results of different measures of spatial access to large food stores and the locations of high and low access identified by each. The data set included U.S. Census population data and the locations of large food stores in the six-county area around Chicago, Illinois. Six measures of spatial access were calculated at the census block group level and the results compared. The analysis found that there was little agreement in the identified locations of high or low access between measures. This study illustrates the importance of considering the access measure used when conducting research, interpreting results, or comparing studies. Future research should explore the correlation of different measures with health behaviors and health outcomes. PMID:26494034

  5. A commuter-based two-step floating catchment area method for measuring spatial accessibility of daycare centers.

    PubMed

    Fransen, Koos; Neutens, Tijs; De Maeyer, Philippe; Deruyter, Greet

    2015-03-01

    This paper puts forward a commuter-based version of the two-step floating catchment area (2SFCA) method, which has gained acceptance in studies on spatial health care accessibility. Current implementations of the 2SFCA method are static in that they consider centroid-based night-time representations of the population. The proposed enhancement to the 2SFCA approach addresses this limitation by accounting for trip-chaining behavior. The presented method is illustrated in a case study of accessibility of daycare centers in the province East Flanders in Belgium. The results show significant spatial differences in accessibility between the original and commuter-based version of the 2SFCA (CB2SFCA). They highlight the importance of giving heed to more complex travel behavior in cases where the need for detailed accessibility calculations is apparent. PMID:25638791

  6. Mof-Tree: A Spatial Access Method To Manipulate Multiple Overlapping Features.

    ERIC Educational Resources Information Center

    Manolopoulos, Yannis; Nardelli, Enrico; Papadopoulos, Apostolos; Proietti, Guido

    1997-01-01

    Investigates the manipulation of large sets of two-dimensional data representing multiple overlapping features, and presents a new access method, the MOF-tree. Analyzes storage requirements and time with respect to window query operations involving multiple features. Examines both the pointer-based and pointerless MOF-tree representations.…

  7. An Enhanced Variable Two-Step Floating Catchment Area Method for Measuring Spatial Accessibility to Residential Care Facilities in Nanjing

    PubMed Central

    Ni, Jianhua; Wang, Jinyin; Rui, Yikang; Qian, Tianlu; Wang, Jiechen

    2015-01-01

    Civil administration departments require reliable measures of accessibility so that residential care facility shortage areas can be accurately identified. Building on previous research, this paper proposes an enhanced variable two-step floating catchment area (EV2SFCA) method that determines facility catchment sizes by dynamically summing the population around the facility until the facility-to-population ratio (FPR) is less than the FPR threshold (FPRT). To minimize the errors from the supply and demand catchments being mismatched, this paper proposes that the facility and population catchment areas must both contain the other location in calculating accessibility. A case study evaluating spatial accessibility to residential care facilities in Nanjing demonstrates that the proposed method is effective in accurately determining catchment sizes and identifying details in the variation of spatial accessibility. The proposed method can be easily applied to assess other public healthcare facilities, and can provide guidance to government departments on issues of spatial planning and identification of shortage and excess areas. PMID:26580637

  8. An Enhanced Variable Two-Step Floating Catchment Area Method for Measuring Spatial Accessibility to Residential Care Facilities in Nanjing.

    PubMed

    Ni, Jianhua; Wang, Jinyin; Rui, Yikang; Qian, Tianlu; Wang, Jiechen

    2015-11-01

    Civil administration departments require reliable measures of accessibility so that residential care facility shortage areas can be accurately identified. Building on previous research, this paper proposes an enhanced variable two-step floating catchment area (EV2SFCA) method that determines facility catchment sizes by dynamically summing the population around the facility until the facility-to-population ratio (FPR) is less than the FPR threshold (FPRT). To minimize the errors from the supply and demand catchments being mismatched, this paper proposes that the facility and population catchment areas must both contain the other location in calculating accessibility. A case study evaluating spatial accessibility to residential care facilities in Nanjing demonstrates that the proposed method is effective in accurately determining catchment sizes and identifying details in the variation of spatial accessibility. The proposed method can be easily applied to assess other public healthcare facilities, and can provide guidance to government departments on issues of spatial planning and identification of shortage and excess areas. PMID:26580637

  9. A hybrid 3D spatial access method based on quadtrees and R-trees for globe data

    NASA Astrophysics Data System (ADS)

    Gong, Jun; Ke, Shengnan; Li, Xiaomin; Qi, Shuhua

    2009-10-01

    3D spatial access method for globe data is very crucial technique for virtual earth. This paper presents a brand-new maintenance method to index 3d objects distributed on the whole surface of the earth, which integrates the 1:1,000,000- scale topographic map tiles, Quad-tree and R-tree. Furthermore, when traditional methods are extended into 3d space, the performance of spatial index deteriorates badly, for example 3D R-tree. In order to effectively solve this difficult problem, a new algorithm of dynamic R-tree is put forward, which includes two sub-procedures, namely node-choosing and node-split. In the node-choosing algorithm, a new strategy is adopted, not like the traditional mode which is from top to bottom, but firstly from bottom to top then from top to bottom. This strategy can effectively solve the negative influence of node overlap. In the node-split algorithm, 2-to-3 split mode substitutes the traditional 1-to-2 mode, which can better concern the shape and size of nodes. Because of the rational tree shape, this R-tree method can easily integrate the concept of LOD. Therefore, it will be later implemented in commercial DBMS and adopted in time-crucial 3d GIS system.

  10. Maximizing Accessibility to Spatially Referenced Digital Data.

    ERIC Educational Resources Information Center

    Hunt, Li; Joselyn, Mark

    1995-01-01

    Discusses some widely available spatially referenced datasets, including raster and vector datasets. Strategies for improving accessibility include: acquisition of data in a software-dependent format; reorganization of data into logical geographic units; acquisition of intelligent retrieval software; improving computer hardware; and intelligent…

  11. Using Geographic Information Systems and Spatial Analysis Methods to Assess Household Water Access and Sanitation Coverage in the SHINE Trial.

    PubMed

    Ntozini, Robert; Marks, Sara J; Mangwadu, Goldberg; Mbuya, Mduduzi N N; Gerema, Grace; Mutasa, Batsirai; Julian, Timothy R; Schwab, Kellogg J; Humphrey, Jean H; Zungu, Lindiwe I

    2015-12-15

    Access to water and sanitation are important determinants of behavioral responses to hygiene and sanitation interventions. We estimated cluster-specific water access and sanitation coverage to inform a constrained randomization technique in the SHINE trial. Technicians and engineers inspected all public access water sources to ascertain seasonality, function, and geospatial coordinates. Households and water sources were mapped using open-source geospatial software. The distance from each household to the nearest perennial, functional, protected water source was calculated, and for each cluster, the median distance and the proportion of households within <500 m and >1500 m of such a water source. Cluster-specific sanitation coverage was ascertained using a random sample of 13 households per cluster. These parameters were included as covariates in randomization to optimize balance in water and sanitation access across treatment arms at the start of the trial. The observed high variability between clusters in both parameters suggests that constraining on these factors was needed to reduce risk of bias. PMID:26602299

  12. Using Geographic Information Systems and Spatial Analysis Methods to Assess Household Water Access and Sanitation Coverage in the SHINE Trial

    PubMed Central

    Ntozini, Robert; Marks, Sara J.; Mangwadu, Goldberg; Mbuya, Mduduzi N. N.; Gerema, Grace; Mutasa, Batsirai; Julian, Timothy R.; Schwab, Kellogg J.; Humphrey, Jean H.; Zungu, Lindiwe I.

    2015-01-01

    Access to water and sanitation are important determinants of behavioral responses to hygiene and sanitation interventions. We estimated cluster-specific water access and sanitation coverage to inform a constrained randomization technique in the SHINE trial. Technicians and engineers inspected all public access water sources to ascertain seasonality, function, and geospatial coordinates. Households and water sources were mapped using open-source geospatial software. The distance from each household to the nearest perennial, functional, protected water source was calculated, and for each cluster, the median distance and the proportion of households within <500 m and >1500 m of such a water source. Cluster-specific sanitation coverage was ascertained using a random sample of 13 households per cluster. These parameters were included as covariates in randomization to optimize balance in water and sanitation access across treatment arms at the start of the trial. The observed high variability between clusters in both parameters suggests that constraining on these factors was needed to reduce risk of bias. PMID:26602299

  13. Methods to measure potential spatial access to delivery care in low- and middle-income countries: a case study in rural Ghana

    PubMed Central

    2014-01-01

    Background Access to skilled attendance at childbirth is crucial to reduce maternal and newborn mortality. Several different measures of geographic access are used concurrently in public health research, with the assumption that sophisticated methods are generally better. Most of the evidence for this assumption comes from methodological comparisons in high-income countries. We compare different measures of travel impedance in a case study in Ghana’s Brong Ahafo region to determine if straight-line distance can be an adequate proxy for access to delivery care in certain low- and middle-income country (LMIC) settings. Methods We created a geospatial database, mapping population location in both compounds and village centroids, service locations for all health facilities offering delivery care, land-cover and a detailed road network. Six different measures were used to calculate travel impedance to health facilities (straight-line distance, network distance, network travel time and raster travel time, the latter two both mechanized and non-mechanized). The measures were compared using Spearman rank correlation coefficients, absolute differences, and the percentage of the same facilities identified as closest. We used logistic regression with robust standard errors to model the association of the different measures with health facility use for delivery in 9,306 births. Results Non-mechanized measures were highly correlated with each other, and identified the same facilities as closest for approximately 80% of villages. Measures calculated from compounds identified the same closest facility as measures from village centroids for over 85% of births. For 90% of births, the aggregation error from using village centroids instead of compound locations was less than 35 minutes and less than 1.12 km. All non-mechanized measures showed an inverse association with facility use of similar magnitude, an approximately 67% reduction in odds of facility delivery per standard

  14. Assessing potential spatial accessibility of health services in rural China: a case study of Donghai county

    PubMed Central

    2013-01-01

    Introduction There is a great health services disparity between urban and rural areas in China. The percentage of people who are unable to access health services due to long travel times increases. This paper takes Donghai County as the study unit to analyse areas with physician shortages and characteristics of the potential spatial accessibility of health services. We analyse how the unequal health services resources distribution and the New Cooperative Medical Scheme affect the potential spatial accessibility of health services in Donghai County. We also give some advice on how to alleviate the unequal spatial accessibility of health services in areas that are more remote and isolated. Methods The shortest traffic times of from hospitals to villages are calculated with an O-D matrix of GIS extension model. This paper applies an enhanced two-step floating catchment area (E2SFCA) method to study the spatial accessibility of health services and to determine areas with physician shortages in Donghai County. The sensitivity of the E2SFCA for assessing variation in the spatial accessibility of health services is checked using different impedance coefficient valuesa. Geostatistical Analyst model and spatial analyst method is used to analyse the spatial pattern and the edge effect of potential spatial accessibility of health services. Results The results show that 69% of villages have access to lower potential spatial accessibility of health services than the average for Donghai County, and 79% of the village scores are lower than the average for Jiangsu Province. The potential spatial accessibility of health services diminishes greatly from the centre of the county to outlying areas. Using a smaller impedance coefficient leads to greater disparity among the villages. The spatial accessibility of health services is greater along highway in the county. Conclusions Most of villages are in underserved health services areas. An unequal distribution of health service

  15. Modeling spatial accessibility of immigrants to culturally diverse family physicians.

    PubMed

    Wanga, Lu; Roisman, Deborah

    2011-01-01

    This article uses accessibility as an analytical tool to examine health care access among immigrants in a multicultural urban setting. It applies and improves on two widely used accessibility models—the gravity model and the two-step floating catchment area model—in measuring spatial accessibility by Mainland Chinese immigrants in the Toronto Census Metropolitan Area. Empirical data on physician-seeking behaviors are collected through two rounds of questionnaire surveys. Attention is focused on journey to physician location and utilization of linguistically matched family physicians. Based on the survey data, a two-zone accessibility model is developed by relaxing the travel threshold and distance impedance parameters that are traditionally treated as a constant in the accessibility models. General linear models are used to identify relationships among spatial accessibility, geography, and socioeconomic characteristics of Mainland Chinese immigrants. The results suggest a spatial mismatch in the supply of and demand for culturally sensitive care, and residential location is the primary factor that determines spatial accessibility to family physicians. The article yields important policy implications. PMID:21488318

  16. Spatial methods for nonstationary fields

    NASA Astrophysics Data System (ADS)

    Nychka, D. W.

    2012-12-01

    Kriging is a non-parametric regression method used in geostatistics for estimating curves and surfaces and forms the core of most statistical methods for spatial data. In climate science these methods are very useful for estimating how climate varies over a geographic region when the observational data is sparse or the computer model runs are limited. A statistical challenge is to implement spatial methods for large sample sizes and also the heterogenity in the physical fields. Both common features of many geophysical problems. Equally important is to provide companion measures of uncertainty so that the estimated surfaces can be compared and interpreted in an objective way. Here we present a new statistical method that can represent nonstationary structure in a field and also scale to large numbers of spatial locations. A practical example is also presented for a subset of the North American Regional Climate Change and Assessment Program model data.

  17. Assessment method of accessibility conditions: how to make public buildings accessible?

    PubMed

    Andrade, Isabela Fernandes; Ely, e Vera Helena Moro Bins

    2012-01-01

    The enforcement of accessibility today has faced several difficulties, such as intervention in historic buildings that now house public services and cultural activities, such as town halls, museums and theaters and should allow access, on equal terms to all people. The paper presents the application of a method for evaluating the spatial accessibility conditions and their results. For this, we sought to support the theoretical foundation about the main issue involved and legislation. From the method used--guided walks--it was possible to identify the main barriers to accessibility in historic buildings. From the identified barriers, possible solutions are presented according to the four components of accessibility: spatial orientation, displacement, use and communication. It is hoped also that the knowledge gained in this research contributes to an improvement of accessibility legislation in relation to the listed items. PMID:22317296

  18. Spatial versus sequential correlations for random access coding

    NASA Astrophysics Data System (ADS)

    Tavakoli, Armin; Marques, Breno; Pawłowski, Marcin; Bourennane, Mohamed

    2016-03-01

    Random access codes are important for a wide range of applications in quantum information. However, their implementation with quantum theory can be made in two very different ways: (i) by distributing data with strong spatial correlations violating a Bell inequality or (ii) using quantum communication channels to create stronger-than-classical sequential correlations between state preparation and measurement outcome. Here we study this duality of the quantum realization. We present a family of Bell inequalities tailored to the task at hand and study their quantum violations. Remarkably, we show that the use of spatial and sequential quantum correlations imposes different limitations on the performance of quantum random access codes: Sequential correlations can outperform spatial correlations. We discuss the physics behind the observed discrepancy between spatial and sequential quantum correlations.

  19. Spatial Big Data Organization, Access and Visualization with ESSG

    NASA Astrophysics Data System (ADS)

    Wu, L. X.; Yu, J. Q.; Yang, Y. Z.; Jia, Y. J.

    2013-10-01

    There are hundreds of spatial reference frame (SRF) being applied, and the great difference among SRFs has blocked the share of global data on planet Earth. A conceptual spheroid of radius 12,800 km and a spheroid degenerated octree grid method are applied to produce an earth system spatial grid (ESSG), which is of natural characteristics to be applied as a new common SRF. A triple CTA is designed as ESSG-based data structure to organize the big data of planet Earth, and a 2D table of a unique label and limitless records for time slices and attribute values is present to record the data of each grid. The big data on planet Earth can hence be gridded and interrelated without discipline gaps and SRF obstacles. An integral data organization mode is designed, and three potential routes are presented for users to access shareable global data in cloud environment. Furthermore, with global crust, atmosphere, DEM, and satellite image being examples, the integrated visualization of global large objects is demonstrated.

  20. A spatial analysis of variations in health access: linking geography, socio-economic status and access perceptions

    PubMed Central

    2011-01-01

    Background This paper analyses the relationship between public perceptions of access to general practitioners (GPs) surgeries and hospitals against health status, car ownership and geographic distance. In so doing it explores the different dimensions associated with facility access and accessibility. Methods Data on difficulties experienced in accessing health services, respondent health status and car ownership were collected through an attitudes survey. Road distances to the nearest service were calculated for each respondent using a GIS. Difficulty was related to geographic distance, health status and car ownership using logistic generalized linear models. A Geographically Weighted Regression (GWR) was used to explore the spatial non-stationarity in the results. Results Respondent long term illness, reported bad health and non-car ownership were found to be significant predictors of difficulty in accessing GPs and hospitals. Geographic distance was not a significant predictor of difficulty in accessing hospitals but was for GPs. GWR identified the spatial (local) variation in these global relationships indicating locations where the predictive strength of the independent variables was higher or lower than the global trend. The impacts of bad health and non-car ownership on the difficulties experienced in accessing health services varied spatially across the study area, whilst the impacts of geographic distance did not. Conclusions Difficulty in accessing different health facilities was found to be significantly related to health status and car ownership, whilst the impact of geographic distance depends on the service in question. GWR showed how these relationships were varied across the study area. This study demonstrates that the notion of access is a multi-dimensional concept, whose composition varies with location, according to the facility being considered and the health and socio-economic status of the individual concerned. PMID:21787394

  1. Neighbourhoods and potential access to health care: the role of spatial and aspatial factors.

    PubMed

    Bissonnette, Laura; Wilson, Kathi; Bell, Scott; Shah, Tayyab Ikram

    2012-07-01

    The availability of, and access to, primary health care is one neighbourhood characteristic that has the potential to impact health thus representing an important area of focus for neighbourhood-health research. This research examines neighbourhood access to primary health care in the city of Mississauga, Ontario, Canada. A modification of the Two Step Floating Catchment Area method is used to measure multiple spatial and aspatial (social) dimensions of potential access to primary health care in natural neighbourhoods of Mississauga. The analysis reveals that neighbourhood-level potential access to primary care is dependant on spatial and aspatial dimensions of access selected for examination. The results also show that potential accessibility is reduced for linguistic minorities as well as for recent immigrant populations who appear, on the surface, to have better access to walk-in clinics than dedicated physicians. The research results reinforce the importance of focusing on intra-urban variations in access to care and demonstrate the utility of a new approach for studying neighbourhood impacts that better represents spatial variations in health care access and demand. PMID:22503565

  2. Measuring Spatial Accessibility of Health Care Providers – Introduction of a Variable Distance Decay Function within the Floating Catchment Area (FCA) Method

    PubMed Central

    Groneberg, David A.

    2016-01-01

    We integrated recent improvements within the floating catchment area (FCA) method family into an integrated ‘iFCA`method. Within this method we focused on the distance decay function and its parameter. So far only distance decay functions with constant parameters have been applied. Therefore, we developed a variable distance decay function to be used within the FCA method. We were able to replace the impedance coefficient β by readily available distribution parameter (i.e. median and standard deviation (SD)) within a logistic based distance decay function. Hence, the function is shaped individually for every single population location by the median and SD of all population-to-provider distances within a global catchment size. Theoretical application of the variable distance decay function showed conceptually sound results. Furthermore, the existence of effective variable catchment sizes defined by the asymptotic approach to zero of the distance decay function was revealed, satisfying the need for variable catchment sizes. The application of the iFCA method within an urban case study in Berlin (Germany) confirmed the theoretical fit of the suggested method. In summary, we introduced for the first time, a variable distance decay function within an integrated FCA method. This function accounts for individual travel behaviors determined by the distribution of providers. Additionally, the function inherits effective variable catchment sizes and therefore obviates the need for determining variable catchment sizes separately. PMID:27391649

  3. Making Spatial Statistics Service Accessible On Cloud Platform

    NASA Astrophysics Data System (ADS)

    Mu, X.; Wu, J.; Li, T.; Zhong, Y.; Gao, X.

    2014-04-01

    Web service can bring together applications running on diverse platforms, users can access and share various data, information and models more effectively and conveniently from certain web service platform. Cloud computing emerges as a paradigm of Internet computing in which dynamical, scalable and often virtualized resources are provided as services. With the rampant growth of massive data and restriction of net, traditional web services platforms have some prominent problems existing in development such as calculation efficiency, maintenance cost and data security. In this paper, we offer a spatial statistics service based on Microsoft cloud. An experiment was carried out to evaluate the availability and efficiency of this service. The results show that this spatial statistics service is accessible for the public conveniently with high processing efficiency.

  4. Spatial accessibility to physical activity facilities and to food outlets and overweight in French youth

    PubMed Central

    Casey, R; Chaix, B; Weber, C; Schweitzer, B; Charreire, H; Salze, P; Badariotti, D; Banos, A; Oppert, J-M; Simon, C

    2012-01-01

    Objective: Some characteristics of the built environment have been associated with obesity in youth. Our aim was to determine whether individual and environmental socio-economic characteristics modulate the relation between youth overweight and spatial accessibility to physical activity (PA) facilities and to food outlets. Design: Cross-sectional study. Subjects: 3293 students, aged 12±0.6 years, randomly selected from eastern France middle schools. Measurements and methods: Using geographical information systems (GIS), spatial accessibility to PA facilities (urban and nature) was assessed using the distance to PA facilities at the municipality level; spatial accessibility to food outlets (general food outlets, bakeries and fast-food outlets) was calculated at individual level using the student home address and the food outlets addresses. Relations of weight status with spatial accessibility to PA facilities and to food outlets were analysed using mixed logistic models, testing potential direct and interaction effects of individual and environmental socio-economic characteristics. Results: Individual socio-economic status modulated the relation between spatial accessibility to PA facilities and to general food outlets and overweight. The likelihood of being overweight was higher when spatial accessibility to urban PA facilities and to general food outlets was low, but in children of blue-collar-workers only. The odds ratio (OR) (95% confidence interval) for being overweight of blue-collar-workers children compared with non-blue-collar-workers children was 1.76 (1.25–2.49) when spatial accessibility to urban PA facilities was low. This OR was 1.86 (1.20–2.86) when spatial accessibility to general food outlets was low. There was no significant relationship of overweight with either nature PA facilities or other food outlets (bakeries and fast-food outlets). Conclusion: These results indicate that disparities in spatial accessibility to PA facilities and to

  5. U.S. Geological Survey spatial data access

    USGS Publications Warehouse

    Faundeen, John L.; Kanengieter, Ronald L.; Buswell, Michael D.

    2002-01-01

    The U.S. Geological Survey (USGS) has done a progress review on improving access to its spatial data holdings over the Web. The USGS EROS Data Center has created three major Web-based interfaces to deliver spatial data to the general public; they are Earth Explorer, the Seamless Data Distribution System (SDDS), and the USGS Web Mapping Portal. Lessons were learned in developing these systems, and various resources were needed for their implementation. The USGS serves as a fact-finding agency in the U.S. Government that collects, monitors, analyzes, and provides scientific information about natural resource conditions and issues. To carry out its mission, the USGS has created and managed spatial data since its inception. Originally relying on paper maps, the USGS now uses advanced technology to produce digital representations of the Earth’s features. The spatial products of the USGS include both source and derivative data. Derivative datasets include Digital Orthophoto Quadrangles (DOQ), Digital Elevation Models, Digital Line Graphs, land-cover Digital Raster Graphics, and the seamless National Elevation Dataset. These products, created with automated processes, use aerial photographs, satellite images, or other cartographic information such as scanned paper maps as source data. With Earth Explorer, users can search multiple inventories through metadata queries and can browse satellite and DOQ imagery. They can place orders and make payment through secure credit card transactions. Some USGS spatial data can be accessed with SDDS. The SDDS uses an ArcIMS map service interface to identify the user’s areas of interest and determine the output format; it allows the user to either download the actual spatial data directly for small areas or place orders for larger areas to be delivered on media. The USGS Web Mapping Portal provides views of national and international datasets through an ArcIMS map service interface. In addition, the map portal posts news about new

  6. The Impact of Varying Statutory Arrangements on Spatial Data Sharing and Access in Regional NRM Bodies

    NASA Astrophysics Data System (ADS)

    Paudyal, D. R.; McDougall, K.; Apan, A.

    2014-12-01

    Spatial information plays an important role in many social, environmental and economic decisions and increasingly acknowledged as a national resource essential for wider societal and environmental benefits. Natural Resource Management is one area where spatial information can be used for improved planning and decision making processes. In Australia, state government organisations are the custodians of spatial information necessary for natural resource management and regional NRM bodies are responsible to regional delivery of NRM activities. The access and sharing of spatial information between government agencies and regional NRM bodies is therefore as an important issue for improving natural resource management outcomes. The aim of this paper is to evaluate the current status of spatial information access, sharing and use with varying statutory arrangements and its impacts on spatial data infrastructure (SDI) development in catchment management sector in Australia. Further, it critically examined whether any trends and significant variations exist due to different institutional arrangements (statutory versus non-statutory) or not. A survey method was used to collect primary data from 56 regional natural resource management (NRM) bodies responsible for catchment management in Australia. Descriptive statistics method was used to show the similarities and differences between statutory and non-statutory arrangements. The key factors which influence sharing and access to spatial information are also explored. The results show the current statutory and administrative arrangements and regional focus for natural resource management is reasonable from a spatial information management perspective and provides an opportunity for building SDI at the catchment scale. However, effective institutional arrangements should align catchment SDI development activities with sub-national and national SDI development activities to address catchment management issues. We found minor

  7. Tools for Online Access and Manipulation of Spatial Climate Data

    NASA Astrophysics Data System (ADS)

    Gibson, W.; Daly, C.; Doggett, M. K.

    2004-12-01

    Oregon State University's Spatial Climate Analysis Service (SCAS) is dedicated to the spatial analysis and mapping of climate. Using the well-known PRISM climate mapping system, SCAS has created digital climate data sets for the US, Canada, parts of Asia and Europe, and elsewhere. Major projects include official USDA precipitation maps for the US, and a new US climate atlas. SCAS also maintains and regularly updates an ongoing monthly time series of digital precipitation, temperature, and dew point maps for the conterminous US, spanning 1895-present. Many PRISM data sets are made accessible to the public online via Web tools that allow users to views map images, download grids, and explore the data. The Minnesota Mapserver has been implemented to allow users to view and query map layers, and create monthly climate time series over the past century for individual grid cells. Time series data are presented as downloadable graphs and tables. Mapserver is also being used by SCAS in a separate Web application, which is geared towards agriculture. In this application, spatial climate and soils data are used to produce suitability maps for various crop species. In the future, we envision greater use of MapServer capabilities for spatial data quality control activities. SCAS is cooperating with the several institutions in developing the WestMap initiative. WestMap aims to provide an easily accessible, comprehensive package of 1 km monthly (or better) resolution climate data series, with associated accuracy estimates, online analysis tools, and educational resources to the highly diverse user communities of climate data stakeholders in the United States.

  8. Residential racial composition, spatial access to care, and breast cancer mortality among women in Georgia.

    PubMed

    Russell, Emily; Kramer, Michael R; Cooper, Hannah L F; Thompson, Winifred Wilkins; Arriola, Kimberly R Jacob

    2011-12-01

    We explored the association between neighborhood residential racial composition and breast cancer mortality among Black and White breast cancer patients in Georgia and whether spatial access to cancer care mediates this association. Participants included 15,256 women living in 15 metropolitan statistical areas in Georgia who were diagnosed with breast cancer between 1999 and 2003. Residential racial composition was operationalized as the percent of Black residents in the census tract. We used gravity-based modeling methods to ascertain spatial access to oncology care. Multilevel Cox proportional hazards models and mediation analyses were used to test associations. Black women were 1.5 times more likely to die from breast cancer than White women. Residential racial composition had a small but significant association with breast cancer mortality (hazard ratios [HRs] = 1.04-1.08 per 10% increase in the percent of Black tract residents). Individual race did not moderate this relationship, and spatial access to care did not mediate it. Residential racial composition may be part of the socioenvironmental milieu that produces increased breast cancer mortality among Black women. However, there is a lack of evidence that spatial access to oncology care mediates these processes. PMID:21847712

  9. Toward Accessing Spatial Structure from Building Information Models

    NASA Astrophysics Data System (ADS)

    Schultz, C.; Bhatt, M.

    2011-08-01

    Data about building designs and layouts is becoming increasingly more readily available. In the near future, service personal (such as maintenance staff or emergency rescue workers) arriving at a building site will have immediate real-time access to enormous amounts of data relating to structural properties, utilities, materials, temperature, and so on. The critical problem for users is the taxing and error prone task of interpreting such a large body of facts in order to extract salient information. This is necessary for comprehending a situation and deciding on a plan of action, and is a particularly serious issue in time-critical and safety-critical activities such as firefighting. Current unifying building models such as the Industry Foundation Classes (IFC), while being comprehensive, do not directly provide data structures that focus on spatial reasoning and spatial modalities that are required for high-level analytical tasks. The aim of the research presented in this paper is to provide computational tools for higher level querying and reasoning that shift the cognitive burden of dealing with enormous amounts of data away from the user. The user can then spend more energy and time in planning and decision making in order to accomplish the tasks at hand. We present an overview of our framework that provides users with an enhanced model of "built-up space". In order to test our approach using realistic design data (in terms of both scale and the nature of the building models) we describe how our system interfaces with IFC, and we conduct timing experiments to determine the practicality of our approach. We discuss general computational approaches for deriving higher-level spatial modalities by focusing on the example of route graphs. Finally, we present a firefighting scenario with alternative route graphs to motivate the application of our framework.

  10. Assessment and Evaluation Methods for Access Services

    ERIC Educational Resources Information Center

    Long, Dallas

    2014-01-01

    This article serves as a primer for assessment and evaluation design by describing the range of methods commonly employed in library settings. Quantitative methods, such as counting and benchmarking measures, are useful for investigating the internal operations of an access services department in order to identify workflow inefficiencies or…

  11. Research Investigation of Information Access Methods

    ERIC Educational Resources Information Center

    Heinrichs, John H.; Sharkey, Thomas W.; Lim, Jeen-Su

    2006-01-01

    This study investigates the satisfaction of library users at Wayne State University who utilize alternative information access methods. The LibQUAL+[TM] desired and perceived that satisfaction ratings are used to determine the user's "superiority gap." By focusing limited library resources to address "superiority gap" issues identified by each…

  12. Regression methods for spatial data

    NASA Technical Reports Server (NTRS)

    Yakowitz, S. J.; Szidarovszky, F.

    1982-01-01

    The kriging approach, a parametric regression method used by hydrologists and mining engineers, among others also provides an error estimate the integral of the regression function. The kriging method is explored and some of its statistical characteristics are described. The Watson method and theory are extended so that the kriging features are displayed. Theoretical and computational comparisons of the kriging and Watson approaches are offered.

  13. Accessibility versus Accuracy in Retrieving Spatial Memory: Evidence for Suboptimal Assumed Headings

    ERIC Educational Resources Information Center

    Yerramsetti, Ashok; Marchette, Steven A.; Shelton, Amy L.

    2013-01-01

    Orientation dependence in spatial memory has often been interpreted in terms of accessibility: Object locations are encoded relative to a reference orientation that affords the most accurate access to spatial memory. An open question, however, is whether people naturally use this "preferred" orientation whenever recalling the space. We…

  14. Fractals and Spatial Methods for Mining Remote Sensing Imagery

    NASA Technical Reports Server (NTRS)

    Lam, Nina; Emerson, Charles; Quattrochi, Dale

    2003-01-01

    The rapid increase in digital remote sensing and GIS data raises a critical problem -- how can such an enormous amount of data be handled and analyzed so that useful information can be derived quickly? Efficient handling and analysis of large spatial data sets is central to environmental research, particularly in global change studies that employ time series. Advances in large-scale environmental monitoring and modeling require not only high-quality data, but also reliable tools to analyze the various types of data. A major difficulty facing geographers and environmental scientists in environmental assessment and monitoring is that spatial analytical tools are not easily accessible. Although many spatial techniques have been described recently in the literature, they are typically presented in an analytical form and are difficult to transform to a numerical algorithm. Moreover, these spatial techniques are not necessarily designed for remote sensing and GIS applications, and research must be conducted to examine their applicability and effectiveness in different types of environmental applications. This poses a chicken-and-egg problem: on one hand we need more research to examine the usability of the newer techniques and tools, yet on the other hand, this type of research is difficult to conduct if the tools to be explored are not accessible. Another problem that is fundamental to environmental research are issues related to spatial scale. The scale issue is especially acute in the context of global change studies because of the need to integrate remote-sensing and other spatial data that are collected at different scales and resolutions. Extrapolation of results across broad spatial scales remains the most difficult problem in global environmental research. There is a need for basic characterization of the effects of scale on image data, and the techniques used to measure these effects must be developed and implemented to allow for a multiple scale assessment of

  15. Spatial Access to Emergency Services in Low- and Middle-Income Countries: A GIS-Based Analysis.

    PubMed

    Tansley, Gavin; Schuurman, Nadine; Amram, Ofer; Yanchar, Natalie

    2015-01-01

    Injury is a leading cause of the global disease burden, accounting for 10 percent of all deaths worldwide. Despite 90 percent of these deaths occurring in low and middle-income countries (LMICs), the majority of trauma research and infrastructure development has taken place in high-income settings. Furthermore, although accessible services are of central importance to a mature trauma system, there remains a paucity of literature describing the spatial accessibility of emergency services in LMICs. Using data from the Service Provision Assessment component of the Demographic and Health Surveys of Namibia and Haiti we defined the capabilities of healthcare facilities in each country in terms of their preparedness to provide emergency services. A Geographic Information System-based network analysis method was used to define 5- 10- and 50-kilometer catchment areas for all facilities capable of providing 24-hour care, higher-level resuscitative services or tertiary care. The proportion of a country's population with access to each level of service was obtained by amalgamating the catchment areas with a population layer. A significant proportion of the population of both countries had poor spatial access to lower level services with 25% of the population of Haiti and 51% of the population of Namibia living further than 50 kilometers from a facility capable of providing 24-hour care. Spatial access to tertiary care was considerably lower with 51% of Haitians and 72% of Namibians having no access to these higher-level services within 50 kilometers. These results demonstrate a significant disparity in potential spatial access to emergency services in two LMICs compared to analogous estimates from high-income settings, and suggest that strengthening the capabilities of existing facilities may improve the equity of emergency services in these countries. Routine collection of georeferenced patient and facility data in LMICs will be important to understanding how spatial access

  16. Spatial Access to Emergency Services in Low- and Middle-Income Countries: A GIS-Based Analysis

    PubMed Central

    Tansley, Gavin; Schuurman, Nadine; Amram, Ofer; Yanchar, Natalie

    2015-01-01

    Injury is a leading cause of the global disease burden, accounting for 10 percent of all deaths worldwide. Despite 90 percent of these deaths occurring in low and middle-income countries (LMICs), the majority of trauma research and infrastructure development has taken place in high-income settings. Furthermore, although accessible services are of central importance to a mature trauma system, there remains a paucity of literature describing the spatial accessibility of emergency services in LMICs. Using data from the Service Provision Assessment component of the Demographic and Health Surveys of Namibia and Haiti we defined the capabilities of healthcare facilities in each country in terms of their preparedness to provide emergency services. A Geographic Information System-based network analysis method was used to define 5- 10- and 50-kilometer catchment areas for all facilities capable of providing 24-hour care, higher-level resuscitative services or tertiary care. The proportion of a country’s population with access to each level of service was obtained by amalgamating the catchment areas with a population layer. A significant proportion of the population of both countries had poor spatial access to lower level services with 25% of the population of Haiti and 51% of the population of Namibia living further than 50 kilometers from a facility capable of providing 24-hour care. Spatial access to tertiary care was considerably lower with 51% of Haitians and 72% of Namibians having no access to these higher-level services within 50 kilometers. These results demonstrate a significant disparity in potential spatial access to emergency services in two LMICs compared to analogous estimates from high-income settings, and suggest that strengthening the capabilities of existing facilities may improve the equity of emergency services in these countries. Routine collection of georeferenced patient and facility data in LMICs will be important to understanding how spatial

  17. High-Resolution Spatial Distribution and Estimation of Access to Improved Sanitation in Kenya

    PubMed Central

    Jia, Peng; Anderson, John D.; Leitner, Michael; Rheingans, Richard

    2016-01-01

    Background Access to sanitation facilities is imperative in reducing the risk of multiple adverse health outcomes. A distinct disparity in sanitation exists among different wealth levels in many low-income countries, which may hinder the progress across each of the Millennium Development Goals. Methods The surveyed households in 397 clusters from 2008–2009 Kenya Demographic and Health Surveys were divided into five wealth quintiles based on their national asset scores. A series of spatial analysis methods including excess risk, local spatial autocorrelation, and spatial interpolation were applied to observe disparities in coverage of improved sanitation among different wealth categories. The total number of the population with improved sanitation was estimated by interpolating, time-adjusting, and multiplying the surveyed coverage rates by high-resolution population grids. A comparison was then made with the annual estimates from United Nations Population Division and World Health Organization /United Nations Children's Fund Joint Monitoring Program for Water Supply and Sanitation. Results The Empirical Bayesian Kriging interpolation produced minimal root mean squared error for all clusters and five quintiles while predicting the raw and spatial coverage rates of improved sanitation. The coverage in southern regions was generally higher than in the north and east, and the coverage in the south decreased from Nairobi in all directions, while Nyanza and North Eastern Province had relatively poor coverage. The general clustering trend of high and low sanitation improvement among surveyed clusters was confirmed after spatial smoothing. Conclusions There exists an apparent disparity in sanitation among different wealth categories across Kenya and spatially smoothed coverage rates resulted in a closer estimation of the available statistics than raw coverage rates. Future intervention activities need to be tailored for both different wealth categories and nationally

  18. Testing the spatial distribution of economic activity in Jiangsu province by means of spatial association methods

    NASA Astrophysics Data System (ADS)

    Ge, Ying; Wang, Weina; Zhang, Shuhui; Yan, Weibiao

    2007-06-01

    The new economic geography theory suggests that regional development is strongly dependent on market access. Due to a snowball effect, spatial clusters of employment and firms might induce regional income increases. In order to identify explicit patterns of regional development, this study makes the empirical attempts by applying spatial association methods for estimating and distinguishing various spatial patterns of economic activities for three county-level factors, namely income, employment and firms of Jiangsu in 2004. The conclusions in this study reveal that on the whole, there is significant, positive correlation of income, employment and firms between regions over the whole space in that year. Moreover, regional income can be to a large extent explained by the market potentials of its neighbors. Apart from market access, regional incomes might be affected by other factors such as local amenities or technology spillover. Also, highly agglomerated clusters of employment and firms give rise to high regional incomes. Strong spatial heterogeneity of employment and firms indicates that firms locate first, anticipating the subsequent consumers' locations and demand functions. Thus, the mobility of firms and employment can induce the highly agglomeration of income.

  19. A spectral method for spatial downscaling.

    PubMed

    Reich, Brian J; Chang, Howard H; Foley, Kristen M

    2014-12-01

    Complex computer models play a crucial role in air quality research. These models are used to evaluate potential regulatory impacts of emission control strategies and to estimate air quality in areas without monitoring data. For both of these purposes, it is important to calibrate model output with monitoring data to adjust for model biases and improve spatial prediction. In this article, we propose a new spectral method to study and exploit complex relationships between model output and monitoring data. Spectral methods allow us to estimate the relationship between model output and monitoring data separately at different spatial scales, and to use model output for prediction only at the appropriate scales. The proposed method is computationally efficient and can be implemented using standard software. We apply the method to compare Community Multiscale Air Quality (CMAQ) model output with ozone measurements in the United States in July 2005. We find that CMAQ captures large-scale spatial trends, but has low correlation with the monitoring data at small spatial scales. PMID:24965037

  20. A Spectral Method for Spatial Downscaling

    PubMed Central

    Reich, Brian J.; Chang, Howard H.; Foley, Kristen M.

    2014-01-01

    Summary Complex computer models play a crucial role in air quality research. These models are used to evaluate potential regulatory impacts of emission control strategies and to estimate air quality in areas without monitoring data. For both of these purposes, it is important to calibrate model output with monitoring data to adjust for model biases and improve spatial prediction. In this article, we propose a new spectral method to study and exploit complex relationships between model output and monitoring data. Spectral methods allow us to estimate the relationship between model output and monitoring data separately at different spatial scales, and to use model output for prediction only at the appropriate scales. The proposed method is computationally efficient and can be implemented using standard software. We apply the method to compare Community Multiscale Air Quality (CMAQ) model output with ozone measurements in the United States in July 2005. We find that CMAQ captures large-scale spatial trends, but has low correlation with the monitoring data at small spatial scales. PMID:24965037

  1. Filter multiplexing by use of spatial Code Division Multiple Access approach.

    PubMed

    Solomon, Jonathan; Zalevsky, Zeev; Mendlovic, David; Monreal, Javier Garcia

    2003-02-10

    The increasing popularity of optical communication has also brought a demand for a broader bandwidth. The trend, naturally, was to implement methods from traditional electronic communication. One of the most effective traditional methods is Code Division Multiple Access. In this research, we suggest the use of this approach for spatial coding applied to images. The approach is to multiplex several filters into one plane while keeping their mutual orthogonality. It is shown that if the filters are limited by their bandwidth, the output of all the filters can be sampled in the original image resolution and fully recovered through an all-optical setup. The theoretical analysis of such a setup is verified in an experimental demonstration. PMID:12593478

  2. Public housing relocations in Atlanta, Georgia, and declines in spatial access to safety net primary care

    PubMed Central

    Cooper, Hannah LF; Wodarski, Stephanie; Cummings, Janet; Hunter-Jones, Josalin; Karnes, Conny; Ross, Zev; Druss, Ben; Bonney, Loida E

    2012-01-01

    This analysis investigates changes in spatial access to safety-net primary care in a sample of US public housing residents relocating via the HOPE VI initiative from public housing complexes to voucher-subsidized rental units; substance misusers were oversampled. We used gravity-based models to measure spatial access to care, and used mixed models to assess pre-/post-relocation changes in access. Half the sample experienced declines in spatial access of ≥79.83%; declines did not vary by substance misuse status. Results suggest that future public housing relocation initiatives should partner with relocaters, particularly those in poor health, to help them find housing near safety-net clinics. PMID:23060002

  3. Public housing relocations in Atlanta, Georgia, and declines in spatial access to safety net primary care.

    PubMed

    Cooper, Hannah L F; Wodarski, Stephanie; Cummings, Janet; Hunter-Jones, Josalin; Karnes, Conny; Ross, Zev; Druss, Ben; Bonney, Loida E

    2012-11-01

    This analysis investigates changes in spatial access to safety-net primary care in a sample of US public housing residents relocating via the HOPE VI initiative from public housing complexes to voucher-subsidized rental units; substance misusers were oversampled. We used gravity-based models to measure spatial access to care, and used mixed models to assess pre-/post-relocation changes in access. Half the sample experienced declines in spatial access of ≥ 79.83%; declines did not vary by substance misuse status. Results suggest that future public housing relocation initiatives should partner with relocaters, particularly those in poor health, to help them find housing near safety-net clinics. PMID:23060002

  4. VIEWCACHE: An incremental database access method for autonomous interoperable databases

    NASA Technical Reports Server (NTRS)

    Roussopoulos, Nick; Sellis, Timoleon

    1991-01-01

    The objective is to illustrate the concept of incremental access to distributed databases. An experimental database management system, ADMS, which has been developed at the University of Maryland, in College Park, uses VIEWCACHE, a database access method based on incremental search. VIEWCACHE is a pointer-based access method that provides a uniform interface for accessing distributed databases and catalogues. The compactness of the pointer structures formed during database browsing and the incremental access method allow the user to search and do inter-database cross-referencing with no actual data movement between database sites. Once the search is complete, the set of collected pointers pointing to the desired data are dereferenced.

  5. VIEWCACHE: An incremental pointer-based access method for autonomous interoperable databases

    NASA Technical Reports Server (NTRS)

    Roussopoulos, N.; Sellis, Timos

    1993-01-01

    One of the biggest problems facing NASA today is to provide scientists efficient access to a large number of distributed databases. Our pointer-based incremental data base access method, VIEWCACHE, provides such an interface for accessing distributed datasets and directories. VIEWCACHE allows database browsing and search performing inter-database cross-referencing with no actual data movement between database sites. This organization and processing is especially suitable for managing Astrophysics databases which are physically distributed all over the world. Once the search is complete, the set of collected pointers pointing to the desired data are cached. VIEWCACHE includes spatial access methods for accessing image datasets, which provide much easier query formulation by referring directly to the image and very efficient search for objects contained within a two-dimensional window. We will develop and optimize a VIEWCACHE External Gateway Access to database management systems to facilitate database search.

  6. VIEWCACHE: An incremental pointer-based access method for autonomous interoperable databases

    NASA Technical Reports Server (NTRS)

    Roussopoulos, N.; Sellis, Timos

    1992-01-01

    One of biggest problems facing NASA today is to provide scientists efficient access to a large number of distributed databases. Our pointer-based incremental database access method, VIEWCACHE, provides such an interface for accessing distributed data sets and directories. VIEWCACHE allows database browsing and search performing inter-database cross-referencing with no actual data movement between database sites. This organization and processing is especially suitable for managing Astrophysics databases which are physically distributed all over the world. Once the search is complete, the set of collected pointers pointing to the desired data are cached. VIEWCACHE includes spatial access methods for accessing image data sets, which provide much easier query formulation by referring directly to the image and very efficient search for objects contained within a two-dimensional window. We will develop and optimize a VIEWCACHE External Gateway Access to database management systems to facilitate distributed database search.

  7. Labour and residential accessibility: a Bayesian analysis based on Poisson gravity models with spatial effects

    NASA Astrophysics Data System (ADS)

    Alonso, M. P.; Beamonte, M. A.; Gargallo, P.; Salvador, M. J.

    2014-10-01

    In this study, we measure jointly the labour and the residential accessibility of a basic spatial unit using a Bayesian Poisson gravity model with spatial effects. The accessibility measures are broken down into two components: the attractiveness component, which is related to its socio-economic and demographic characteristics, and the impedance component, which reflects the ease of communication within and between basic spatial units. For illustration purposes, the methodology is applied to a data set containing information about commuters from the Spanish region of Aragón. We identify the areas with better labour and residential accessibility, and we also analyse the attractiveness and the impedance components of a set of chosen localities which allows us to better understand their mobility patterns.

  8. Method for Accessing Distributed Heterogeneous Databases

    NASA Technical Reports Server (NTRS)

    Jacobs, B. E.

    1984-01-01

    A scenario of relational, hierarchial, and network data bases is presented and a distributed access view integrated data base system (DAVID) is described for uniformly accessing data bases which are heterogeneous and physically distributed. The DAVID system is based on data base logic so that the relational approach is generalized to the heterogeneous approach. The global data manager is explained as are global data manipulation languages which can operate on all the data bases and can query the data dictionary and the data directory.

  9. Spatial Data Access Tool: Enable visualization and access of geospatial data using OGC services and Google Earth

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Santhana Vannan, S.; Cook, R. B.; Wilson, B. E.; Beaty, T.

    2009-12-01

    The Spatial Data Access Tool (SDAT) deployed in the Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC, http://daac.ornl.gov) and the Modeling and Synthesis Thematic Data Center (MAST-DC, http://nacp.ornl.gov/) provides visualization and access to a number of land cover, biophysical, elevation, ecosystem, climate, soil, and model output data sets using Open Geospatial Consortium (OGC) services. OGC services such as Web Map Service (WMS) and Web Coverage Service (WCS) provide applications and users visualization and access to geospatial data in different spatial/temporal extent, projection, resolution, and data format. OGC WMS allows users to visualize the data, and OGC WCS allows users to access the data. Based on OGC WMS, the SDAT tool provides two options for geospatial data visualization. The first option is a Web-based interface that utilizes open source library, OpenLayers, to interact with OGC WMS to produce dynamic maps. This interface also provides options for users to specify WCS parameters, such as projection and resolution, to download geospatial data. The second option is a Google Earth KMZ file created for each data set. The Google Earth KMZ files use the OGC WMS internally to provide visualization of the data dynamically within the Google Earth software. Using Google Earth and OGC WMS, it is possible for users to visualize the spatial pattern within a large extent and also to investigate the details in finer resolution. The KMZ files provide the capability to play time series animation if a data set contains multiple time steps. The KMZ files are also hyperlinked to the SDAT tool for each data granule so that users can easily download the geospatial data after visualizing them in Google Earth. Future work includes adding more geospatial data, supporting more data formats and projections, and deploying Web Feature Service (WFS) to support vector data.

  10. Location-allocation and accessibility models for improving the spatial planning of public health services.

    PubMed

    Polo, Gina; Acosta, C Mera; Ferreira, Fernando; Dias, Ricardo Augusto

    2015-01-01

    This study integrated accessibility and location-allocation models in geographic information systems as a proposed strategy to improve the spatial planning of public health services. To estimate the spatial accessibility, we modified the two-step floating catchment area (2SFCA) model with a different impedance function, a Gaussian weight for competition among service sites, a friction coefficient, distances along a street network based on the Dijkstra's algorithm and by performing a vectorial analysis. To check the accuracy of the strategy, we used the data from the public sterilization program for the dogs and cats of Bogot´a, Colombia. Since the proposed strategy is independent of the service, it could also be applied to any other public intervention when the capacity of the service is known. The results of the accessibility model were consistent with the sterilization program data, revealing that the western, central and northern zones are the most isolated areas under the sterilization program. Spatial accessibility improvement was sought by relocating the sterilization sites using the maximum coverage with finite demand and the p-median models. The relocation proposed by the maximum coverage model more effectively maximized the spatial accessibility to the sterilization service given the non-uniform distribution of the populations of dogs and cats throughout the city. The implementation of the proposed strategy would provide direct benefits by improving the effectiveness of different public health interventions and the use of financial and human resources. PMID:25775411

  11. Location-Allocation and Accessibility Models for Improving the Spatial Planning of Public Health Services

    PubMed Central

    Polo, Gina; Acosta, C. Mera; Ferreira, Fernando; Dias, Ricardo Augusto

    2015-01-01

    This study integrated accessibility and location-allocation models in geographic information systems as a proposed strategy to improve the spatial planning of public health services. To estimate the spatial accessibility, we modified the two-step floating catchment area (2SFCA) model with a different impedance function, a Gaussian weight for competition among service sites, a friction coefficient, distances along a street network based on the Dijkstra’s algorithm and by performing a vectorial analysis. To check the accuracy of the strategy, we used the data from the public sterilization program for the dogs and cats of Bogot´a, Colombia. Since the proposed strategy is independent of the service, it could also be applied to any other public intervention when the capacity of the service is known. The results of the accessibility model were consistent with the sterilization program data, revealing that the western, central and northern zones are the most isolated areas under the sterilization program. Spatial accessibility improvement was sought by relocating the sterilization sites using the maximum coverage with finite demand and the p-median models. The relocation proposed by the maximum coverage model more effectively maximized the spatial accessibility to the sterilization service given the non-uniform distribution of the populations of dogs and cats throughout the city. The implementation of the proposed strategy would provide direct benefits by improving the effectiveness of different public health interventions and the use of financial and human resources. PMID:25775411

  12. Intravenous access: a comparison of two methods.

    PubMed

    Duffy, B L; Lee, J S

    1983-05-01

    The reliability in providing a continued venous route to the circulation is compared between a winged needle (Abbott "Butterfly--23 INT") and a plastic catheter (Jelco Teflon "Catheter Placement Unit", 22 gauge). The catheter remained within the vein in all cases and had a much lower incidence of total obstruction during the study period. Where an intravenous infusion is not in place, a plastic catheter provides a more reliable access route to the circulation than does a winged needle. PMID:6869776

  13. Practical aspects of spatially high accurate methods

    NASA Technical Reports Server (NTRS)

    Godfrey, Andrew G.; Mitchell, Curtis R.; Walters, Robert W.

    1992-01-01

    The computational qualities of high order spatially accurate methods for the finite volume solution of the Euler equations are presented. Two dimensional essentially non-oscillatory (ENO), k-exact, and 'dimension by dimension' ENO reconstruction operators are discussed and compared in terms of reconstruction and solution accuracy, computational cost and oscillatory behavior in supersonic flows with shocks. Inherent steady state convergence difficulties are demonstrated for adaptive stencil algorithms. An exact solution to the heat equation is used to determine reconstruction error, and the computational intensity is reflected in operation counts. Standard MUSCL differencing is included for comparison. Numerical experiments presented include the Ringleb flow for numerical accuracy and a shock reflection problem. A vortex-shock interaction demonstrates the ability of the ENO scheme to excel in simulating unsteady high-frequency flow physics.

  14. Measuring spatial accessibility to healthcare for populations with multiple transportation modes.

    PubMed

    Mao, Liang; Nekorchuk, Dawn

    2013-11-01

    Few measures of healthcare accessibility have considered multiple transportation modes when people seek healthcare. Based on the framework of the 2 Step Floating Catchment Area Method (2SFCAM), we proposed an innovative method to incorporate transportation modes into the accessibility estimation. Taking Florida, USA, as a study area, we illustrated the implementation of the multi-mode 2SFCAM, and compared the accessibility estimates with those from the traditional single-mode 2SFCAM. The results suggest that the multi-modal method, by accounting for heterogeneity in populations, provides more realistic accessibility estimations, and thus offers a better guidance for policy makers to mitigate health inequity issues. PMID:24077335

  15. The limited access paradigm: description of one method.

    PubMed

    Sinclair, J D; Hyytiä, P; Nurmi, M

    1992-01-01

    Restricting access to alcohol to a short period daily causes rats, in effect, to drink on command. They usually begin drinking alcohol immediately when it is first made available each day and consume a rather constant amount during each access period. The procedure thus has a variety of useful applications. The specific method reported here in detail provides continual access to food and water, but access to unflavored 10% ethanol solution only 1 h/d, all in the home cage, and produces mean alcohol intakes from 0.5-1.0 g/kg in the access hour. PMID:1418671

  16. Spatial accessibility of the population to urban health centres in Kermanshah, Islamic Republic of Iran: a geographic information systems analysis.

    PubMed

    Reshadat, S; Saedi, S; Zangeneh, A; Ghasemi, S R; Gilan, N R; Karbasi, A; Bavandpoor, E

    2015-06-01

    Geographic information systems (GIS) analysis has not been widely used in underdeveloped countries to ensure that vulnerable populations have accessibility to primary health-care services. This study applied GIS methods to analyse the spatial accessibility to urban primary-care centres of the population in Kermanshah city, Islamic Republic of Iran, by age and sex groups. In a descriptive-analytical study over 3 time periods, network analysis, mean centre and standard distance methods were applied using ArcGIS 9.3. The analysis was based on a standard radius of 750 m distance from health centres, walking speed of 1 m/s and desired access time to health centres of 12.5 mins. The proportion of the population with inadequate geographical access to health centres rose from 47.3% in 1997 to 58.4% in 2012. The mean centre and standard distance mapping showed that the spatial distribution of health centres in Kermanshah needed to be adjusted to changes in population distribution. PMID:26369997

  17. Lunar archive panoramas: modern image processing and access to the historic data based on spatial context

    NASA Astrophysics Data System (ADS)

    Kozlova, Natalia; Kokhanov, Alexander; Oberst, Jürgen; Zubarev, Anatoliy; Nadezhdina, Irina; Patraty, Vyacheslav; Karachevtseva, Irina; Garov, Andrey; Matveev, Evgeniy

    The objectives of our work are to fully exploit the historic Soviet Lunokhod data and use the results for scientific and public purposes. Unfortunately, many of the relevant operational parameters of the Lunokhods missions are lost. Modern photogrammetry is a key to solving these issues, providing analysis techniques, not available at the time of the early lunar missions. For this purpose we use special developed software, GIS tools and high-resolution LRO data [1]. Results of new image processing of historic data are part of PRoViDE project (Planetary Robotics Vision Data Exploitation) which aims to assemble a major portion of the imaging data gathered from different vehicles and probes on planetary surfaces into a unique database, bringing them into a spatial context and providing access to a complete set of 3D vision products (http://www.provide-space.eu/). Our technology of archive panorama processing allows us to recover lost information of Soviet lunar missions and study lunar landing site imagery by state-of-the-art photogrammetric techniques. Our main task is to perform lunar panoramas in measurement form based on photogrammetry and geoanalyses methods, and then involve them in more detailed morphometric analyses [2] and 3D-modeling of lunar surface based on LROC NAC image processing [3]. The results of our work are various types of new products: panoramas in different projections, updated metadata with recovering parameters, and ortho-panoramas, which can be used for quantitative geomorphology assessment based on spatial tools [4]. All data products obtained as a result of the study are to be placed into Planetary data storage which is developing as Geodesy and Cartography Node [5]. Access to archive lunar data will be organized via Geo-portal (http://cartsrv.mexlab.ru/geoportal/) using authorization service, which provided data security and user control. Planetary spatial information system can integrate various types of data for planets and their

  18. Method and apparatus for globally-accessible automated testing

    DOEpatents

    Layne, Scott P.; Beugelsdijk, Tony J.

    1998-01-01

    A method and apparatus for sharing integrated testing services with a plurality of autonomous remote clients is disclosed. In the disclosed method, in response to an access request message, a process controller transmits an access enabling message to the remote client. The access enabling message includes instructions performable by a remote client to generate test equipment commands. A process controller interprets and transforms these commands into automated test instrument suite commands, which are provided to laboratory modules to perform the indicated tests. Test data results are then obtained and transmitted to the remote client.

  19. Formation of spatial thinking skills through different training methods.

    PubMed

    Kornkasem, Sorachai; Black, John B

    2015-09-01

    Spatial training can be durable and transferable if the training involves cognitive process-based tasks. The current study explored different spatial training methods and investigated the sequences of process-based mental simulation that was facilitated by various structures of external spatial representation, 3D technology, spatial cues, and/or technical languages. A total of 115 Columbia University's students were conducted through three experiments using a between-subjects design to examine the effects of spatial training methods on spatial ability performance. The conditions for training environments included 3D-virtual and 3D-physical interactions with abstract (nonsense-geometric) and concrete (everyday-object) contents. Overall, learners in the treatment conditions improved in their spatial skills significantly more than those in the control conditions. Particularly, 3D-direct-manipulation conditions in the third experiment added promising results about the specific sequences during spatial thinking formation processes. PMID:26224268

  20. An Efficient Method for the Retrieval of Objects by Topological Relations in Spatial Database Systems.

    ERIC Educational Resources Information Center

    Lin, P. L.; Tan, W. H.

    2003-01-01

    Presents a new method to improve the performance of query processing in a spatial database. Experiments demonstrated that performance of database systems can be improved because both the number of objects accessed and number of objects requiring detailed inspection are much less than those in the previous approach. (AEF)

  1. New Earth Science Data and Access Methods

    NASA Technical Reports Server (NTRS)

    Moses, John F.; Weinstein, Beth E.; Farnham, Jennifer

    2004-01-01

    NASA's Earth Science Enterprise, working with its domestic and international partners, provides scientific data and analysis to improve life here on Earth. NASA provides science data products that cover a wide range of physical, geophysical, biochemical and other parameters, as well as services for interdisciplinary Earth science studies. Management and distribution of these products is administered through the Earth Observing System Data and Information System (EOSDIS) Distributed Active Archive Centers (DAACs), which all hold data within a different Earth science discipline. This paper will highlight selected EOS datasets and will focus on how these observations contribute to the improvement of essential services such as weather forecasting, climate prediction, air quality, and agricultural efficiency. Emphasis will be placed on new data products derived from instruments on board Terra, Aqua and ICESat as well as new regional data products and field campaigns. A variety of data tools and services are available to the user community. This paper will introduce primary and specialized DAAC-specific methods for finding, ordering and using these data products. Special sections will focus on orienting users unfamiliar with DAAC resources, HDF-EOS formatted data and the use of desktop research and application tools.

  2. Exploring the relationship between food access and foodborne illness by using spatial analysis.

    PubMed

    Newbold, Bruce; Watson, Susannah; Mackay, Kevin; Isaacs, Sandy

    2013-09-01

    There is some evidence that neighborhood deprivation increases residents' risk of foodborne illnesses. Because urban areas with the least available access to adequate amounts of nutritious or affordable food options (or "food deserts") also tend to be the most deprived areas within a city, it is hypothesized that food access and foodborne illness risk are linked. However, the complexity of tracking numbers and sources of gastrointestinal (GI) illnesses often leads researchers to speculate about reasons for disproportionate rates of pathogen outbreaks among demographic groups. This study explores the suitability of existing data to examine associations between food deserts and the spatial distribution of GI illnesses in Hamilton, Ontario, Canada. A spatial analysis by using GIS software methodology was used to identify and map food retail outlets and accessibility, as well as GI illness outbreaks and sales of antidiarrhea, antinausea, and rehydration products (used as a proxy for GI cases) within the city, based on available data. Statistical analysis of the maps shows no statistical relationship between location, access to food outlets, and rates of GI illness. The analysis points to shortfalls and gaps in the existing data, which leaves us unable to draw conclusions either supporting or refuting our hypothesis. This article includes recommendations to improve the current system of illness reporting and to continue to refine the definition and process of mapping food access issues. A more comprehensive set of data would enable municipalities to more easily identify groups most at risk, depending on exposures and the type of pathogen, and reduce the occurrence of foodborne disease. PMID:23992507

  3. Spatial Accessibility of Drug Treatment Facilities and the Effects on Locus of Control, Drug Abuse, and Service Use among Heroin-Injecting Mexican American Men

    PubMed Central

    Kao, Dennis; Torres, Luis R.; Guerrero, Erick G.; Mauldin, Rebecca; Bordnick, Patrick S.

    2014-01-01

    Background This study explores the spatial accessibility of outpatient drug treatment facilities and the potential relationship with drug abuse-related outcomes among Mexican American heroin users. Methods Secondary data on 219 current and former heroin-injecting Mexican American men aged 45 and older were drawn from a research study in Houston, Texas. We used geographic information systems (GIS) to derive two spatial accessibility measures: distance from one’s place of residence to the closest drug treatment facility (in minutes); and the number of facilities within a 10-minute driving distance from one’s place of residence. Exploratory logistic regression analyses examined the association between the spatial accessibility of drug treatment facilities and several drug abuse-related outcomes: internal locus of control (LOC); perceived chances and worries of injecting in the next six months; treatment utilization; and location of last heroin purchase. Results Participants with greater spatial access to treatment programs were more likely to report a higher chance of injecting in the near future. However, while current heroin users were more worried about injecting in the next six months, greater spatial access to treatment programs seemed to have a buffering effect. Finally, those who lived closer to a treatment programs were more likely to have last purchased heroin inside the neighborhood versus outside the neighborhood. Spatial accessibility was not associated with internal LOC or treatment utilization. Conclusion The findings showed that the presence of outpatient treatment facilities—particularly services in Spanish—may influence perceived risk of future heroin use and purchasing behaviors among Mexican American men. Implications for future spatially-informed drug abuse research and the planning of culturally and linguistically responsive drug treatment programs are discussed. PMID:24440123

  4. Spatial accessibility to vaccination sites in a campaign against rabies in São Paulo city, Brazil.

    PubMed

    Polo, Gina; Acosta, Carlos Mera; Dias, Ricardo Augusto

    2013-08-01

    It is estimated that the city of São Paulo has over 2.5 million dogs and 560 thousand cats. These populations are irregularly distributed throughout the territory, making it difficult to appropriately allocate health services focused on these species. To reasonably allocate vaccination sites, it is necessary to identify social groups and their access to the referred service. Rabies in dogs and cats has been an important zoonotic health issue in São Paulo and the key component of rabies control is vaccination. The present study aims to introduce an approach to quantify the potential spatial accessibility to the vaccination sites of the 2009 campaign against rabies in the city of São Paulo and solve the overestimation associated with the classic methodology that applies buffer zones around vaccination sites based on Euclidean (straight-line) distance. To achieve this, a Gaussian-based two-step floating catchment area method with a travel-friction coefficient was adapted in a geographic information system environment, using distances along a street network based on Dijkstra's algorithm (short path method). The choice of the distance calculation method affected the results in terms of the population covered. In general, areas with low accessibility for both dogs and cats were observed, especially in densely populated areas. The eastern zone of the city had higher accessibility values compared with peripheral and central zones. The Gaussian-based two-step floating catchment method with a travel-friction coefficient was used to assess the overestimation of the straight-line distance method, which is the most widely used method for coverage analysis. We conclude that this approach has the potential to improve the efficiency of resource use when planning rabies control programs in large urban environments such as São Paulo. The findings emphasize the need for surveillance and intervention in isolated areas. PMID:23602338

  5. A mobile agent approach to access and represent remote spatial information in LBS

    NASA Astrophysics Data System (ADS)

    Fang, Zhixiang; Li, Qingquan; Luo, Zhi; Geng, Xuexian

    2005-10-01

    The mobile computing based Location based Service (LBS) technology has been increasingly grown in the past decade; however there still exist some important constraints that complicate work with a mobile spatial information system. The limited resources in the mobile computing terminals would restrict some features that are available on the traditional computing technology. This paper will explores the use of a cooperative, distributed multi-agent systems (Java Agent Development Framework, JADE) to improve the efficiency of accessing and represent remote spatial information in mobile terminals and fixed terminal which support Java runtime environment (JRE), because that JADE system has following features: distributed agent platform, graphical user interface to manage several agents and agent containers form remote host, supporting to execution of multiple, parallel and concurrent agent activities via behavior model, FIPA-compliant platform including AMS (Agent Management System), DF (Directory Facilitator) and ACC (Agent Communication Channel), Efficient transport of ACL messages inside same agent system, library of FIPA interaction protocols ready to be used, FIPA-compliant naming service and supporting for application-defined content languages and ontology. An agile and flexible agent based approach for accessing and representing remote spatial information is proposed in this paper, mobile agent system architecture in LBS is presented, and a prototype system is given to shown that JADE makes this approach feasible and effective.

  6. Methods for spatial localization in NMR

    SciTech Connect

    Rath, A.R.

    1985-01-01

    Several unique coil configurations were developed that have applications in nuclear magnetic resonance. These include a number of designs appropriate for use as rf surface coils, and two configurations developed as NMR magnets. The magnetic field profiles were calculated for each of these designs, from which field strength and homogeneity information were obtained. The rf coil configurations modelled include the opposed loop, opposed half loop, bicycle wheel, opposed bicycle wheel, and semi-toroid. The opposed loop design was studied in detail in terms of the theoretical spatial sensitivity and selectivity it offers. A number of NMR experiments were performed to test the validity of these theoretical calculations. This configuration produces a field that is substantially reduced near the coil itself, compared with the field produced by a single loop surface coil, but that rises to a maximum along the coil axis yielding a somewhat homogeneous region that may be used to achieve a degree of spatial localization. Several comparison schemes are used to evaluate the relative advantages and disadvantages of both the single loop and the opposed loop coil. The opposed coil concept also has been applied to the design of magnets. The results of calculations on the homogeneity and field strength possible with an opposed solenoid magnet are presented.

  7. Developing a composite index of spatial accessibility across different health care sectors: A German example.

    PubMed

    Siegel, Martin; Koller, Daniela; Vogt, Verena; Sundmacher, Leonie

    2016-02-01

    The evolving lack of ambulatory care providers especially in rural areas increasingly challenges the strict separation between ambulatory and inpatient care in Germany. Some consider allowing hospitals to treat ambulatory patients to tackle potential shortages of ambulatory care in underserved areas. In this paper, we develop an integrated index of spatial accessibility covering multiple dimensions of health care. This index may contribute to the empirical evidence concerning potential risks and benefits of integrating the currently separated health care sectors. Accessibility is measured separately for each type of care based on official data at the district level. Applying an Improved Gravity Model allows us to factor in potential cross-border utilization. We combine the accessibilities for each type of care into a univariate index by adapting the concept of regional multiple deprivation measurement to allow for a limited substitutability between health care sectors. The results suggest that better health care accessibility in urban areas persists when taking a holistic view. We believe that this new index may provide an empirical basis for an inter-sectoral capacity planning. PMID:26831039

  8. Method for spatially distributing a population

    DOEpatents

    Bright, Edward A [Knoxville, TN; Bhaduri, Budhendra L [Knoxville, TN; Coleman, Phillip R [Knoxville, TN; Dobson, Jerome E [Lawrence, KS

    2007-07-24

    A process for spatially distributing a population count within a geographically defined area can include the steps of logically correlating land usages apparent from a geographically defined area to geospatial features in the geographically defined area and allocating portions of the population count to regions of the geographically defined area having the land usages, according to the logical correlation. The process can also include weighing the logical correlation for determining the allocation of portions of the population count and storing the allocated portions within a searchable data store. The logically correlating step can include the step of logically correlating time-based land usages to geospatial features of the geographically defined area. The process can also include obtaining a population count for the geographically defined area, organizing the geographically defined area into a plurality of sectors, and verifying the allocated portions according to direct observation.

  9. Rearing without early access to perches impairs the spatial skills of laying hens.

    PubMed

    Gunnarsson; Yngvesson; Keeling; Forkman

    2000-04-01

    The effect of rearing with and without perches on the spatial ability of domestic hens (Gallus gallus domesticus) was investigated. No access or late access to perches during rearing has been shown to increase the later prevalence of floor eggs and cloacal cannibalism in loose-housed laying hens. This may be explained by either the birds reared without perches have difficulty using perches due to low muscle strength, lack of motor skills, and inability to keep balance, or they have impaired spatial skills necessary for moving around in three-dimensional space. These alternative explanations are not mutually exclusive.Thirty, day-old chicks were randomly allocated into two equal groups and reared in litter pens, one with access to perches (P+) and one without (P-). At 8 weeks of age, all birds were given access to perches, and by 15 weeks, all birds were using perches for roosting at night. At 16 weeks, 10 birds from each group were tested in pens where food was presented on a wire mesh tier 40 cm above the ground (T40). Three consecutive tests, with increasing difficulty for the bird to reach the food, were then performed. Firstly, the food was presented at 80 cm above the ground but with the tier at 40 cm still present; secondly, food was presented on the tier at 80 cm; and then, finally, with the food on a 160 cm high tier with the tier at 80 cm still present. All birds were food deprived for 15 h before each test and the time from the bird entering the pen until reaching the food was recorded. There was no difference in the time to reach the food between P+ and P- birds in the T40 test. But as the difficulty of the task increased, the difference between the P+ and P- birds became significant, with the P- birds taking a longer time to reach the food or not reaching it at all. Since there was no difference between P+ and P- in the T40 test, it seems reasonable to suppose that the later differences did not depend on differences in physical ability. Therefore, the

  10. Race, spatial mismatch, and job accessibility: evidence from a plant relocation.

    PubMed

    Fernandez, Roberto M

    2008-09-01

    One of the most prominent explanations for minority underachievement in the labor market is what has been termed the spatial mismatch hypothesis. The original formulation of the hypothesis by John Kain focused on the effects of racially segregated housing on workers' labor market outcomes assuming race-neutral employers. This paper reports the results of a case study designed to test Kain's original conception of this important hypothesis within the context of a longitudinal analysis of a relocating food processing plant. Because the workers in this study did not choose the firm's new location, the relocation can be treated as an exogenous, demand-side shock to the local labor market. This natural experiment design solves the major problem of extant approaches to the theory, i.e., the selective migration of minorities to areas with high concentrations of jobs. The study design also eliminates the confounding factor of non-race-neutral employers using space as a means to discriminate against minorities since the circumstances of this move make us confident that the firm is not moving for racial motives. We find support in favor of Kain's version of the spatial mismatch hypothesis. Despite the firm's best intentions and work to minimize the impact of the spatial disruption caused by the relocation, the racial segregation of the area's housing market hampered minorities' adjustments to the relocation. Consistent with Kain's formulation, spatially discriminating employers are not needed to produce race differences in job accessibility; racially segregated housing markets alone can generate such outcomes. PMID:19086118

  11. Spatial-Temporal dynamics of surface water flooding and consequences for emergency services accessibility

    NASA Astrophysics Data System (ADS)

    Pattison, Ian; Green, Daniel; Yu, Dapeng; Bosher, Lee; Wilby, Rob; Yang, Lili; Ryley, Tim

    2016-04-01

    Urban areas are increasingly susceptible to surface water flooding, with more intense precipitation and intensification of land development. Flooding has both direct impacts i.e. locations inundated with water, and indirect impacts i.e. transport networks, utility e.g. electricity/water services etc. The direct areas flooded evolve in space through the event, and are predicted by standard inundation models. However, the wider indirect impacts and the spatial-temporal patterns are less constrained and it is these that are needed to manage the impacts in real-time. This paper focusses on the Category One responders of the Fire and Rescue and Ambulance Services in the City of Leicester, East Midlands, UK. Leicester is ranked 16th out of 4215 settlements at risk of surface water flooding in the UK based upon the population at risk (15,200 people) (DEFRA, 2009). The analysis undertaken involved overlaying the flood extent with the Integrated Transport Network (ITN) data within a GIS framework. Then a simple transport routing algorithm was used to predict the travel time from specific nodes representing ambulance or fire stations to different parts of the city. Flood magnitudes with 1:20, 1:100 and 1:1000 return periods have been investigated. Under a scenario of no flooding, 100% of the city is accessible by the six fire stations in the city. However, in the 1 in 20 year surface water flood event the peak inundation results in 66.5% being accessible in the 10 minute permitted time and 6% is totally inaccessible. This falls to 40% and 13% respectively for the 1 in 100 year event. Maps show the area of the city that are accessible by two or more stations within the permitted response time, which shows these areas are the most resilient to surface water flooding. However, it isn't just the peak water depths at every location which impacts accessibility within the city but the spatial-temporal patterns of the inundation. The areas within the 10 minute response time expand

  12. Systems and methods for knowledge discovery in spatial data

    DOEpatents

    Obradovic, Zoran; Fiez, Timothy E.; Vucetic, Slobodan; Lazarevic, Aleksandar; Pokrajac, Dragoljub; Hoskinson, Reed L.

    2005-03-08

    Systems and methods are provided for knowledge discovery in spatial data as well as to systems and methods for optimizing recipes used in spatial environments such as may be found in precision agriculture. A spatial data analysis and modeling module is provided which allows users to interactively and flexibly analyze and mine spatial data. The spatial data analysis and modeling module applies spatial data mining algorithms through a number of steps. The data loading and generation module obtains or generates spatial data and allows for basic partitioning. The inspection module provides basic statistical analysis. The preprocessing module smoothes and cleans the data and allows for basic manipulation of the data. The partitioning module provides for more advanced data partitioning. The prediction module applies regression and classification algorithms on the spatial data. The integration module enhances prediction methods by combining and integrating models. The recommendation module provides the user with site-specific recommendations as to how to optimize a recipe for a spatial environment such as a fertilizer recipe for an agricultural field.

  13. Emissions from residential combustion considering end-uses and spatial constraints: Part I, methods and spatial distribution

    NASA Astrophysics Data System (ADS)

    Winijkul, Ekbordin; Fierce, Laura; Bond, Tami C.

    2016-01-01

    This study describes a framework to attribute national-level atmospheric emissions in the year 2010 from the residential sector, one of the largest energy-related sources of aerosol emissions. We place special emphasis on end-uses, dividing usage into cooking, heating, lighting, and others. This study covers regions where solid biomass fuel provides more than 50% of total residential energy: Latin America, Africa, and Asia (5.2 billion people in 2010). Using nightlight data and population density, we classify five land types: urban, electrified rural with forest access, electrified rural without forest access, non-electrified rural with forest access, and non-electrified rural without forest access. We then apportion national-level residential fuel consumption among all land-types and end-uses, and assign end-use technologies to each combination. The resulting calculation gives spatially-distributed emissions of particulate matter, black carbon, organic carbon, nitrogen oxides, methane, non-methane hydrocarbons, carbon monoxide, and carbon dioxide. Within this study region, about 13% of the energy is consumed in urban areas, and 45% in non-urban land near forests. About half the energy is consumed in land without access to electricity. Cooking accounts for 54% of the consumption, heating for 9%, and lighting only 2%, with unidentified uses making up the remainder. Because biofuel use is assumed to occur preferentially where wood is accessible and electricity is not, our method shifts emissions to land types without electrification, compared with previous methods. The framework developed here is an important first step in acknowledging the role of household needs and local constraints in choosing energy provision. Although data and relationships described here need further development, this structure offers a more physically-based understanding of residential energy choices and, ultimately, opportunities for emission reduction.

  14. 5 CFR 297.202 - Methods of access.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Methods of access. 297.202 Section 297.202 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PRIVACY..., Office of Personnel Management offices will not furnish certified copies of records. When copies are...

  15. Quantitative measurements of inequality in geographic accessibility to pediatric care in Oita Prefecture, Japan: Standardization with complete spatial randomness

    PubMed Central

    2011-01-01

    Background A quantitative measurement of inequality in geographic accessibility to pediatric care as well as that of mean distance or travel time is very important for priority setting to ensure fair access to pediatric facilities. However, conventional techniques for measuring inequality is inappropriate in geographic settings. Since inequality measures of access distance or travel time is strongly influenced by the background geographic distribution patterns, they cannot be directly used for regional comparisons of geographic accessibility. The objective of this study is to resolve this issue by using a standardization approach. Methods Travel times to the nearest pediatric care were calculated for all children in Oita Prefecture, Japan. Relative mean differences were considered as the inequality measure for secondary medical service areas, and were standardized with an expected value estimated from a Monte Carlo simulation based on complete spatial randomness. Results The observed mean travel times in the area considered averaged 4.50 minutes, ranging from 1.83 to 7.02 minutes. The mean of the observed inequality measure was 1.1, ranging from 0.9 to 1.3. The expected values of the inequality measure varied according to the background geographic distribution pattern of children, which ranged from 0.3 to 0.7. After standardizing the observed inequality measure with the expected one, we found that the ranks of the inequality measure were reversed for the observed areas. Conclusions Using the indicator proposed in this paper, it is possible to compare the inequality in geographic accessibility among regions. Such a comparison may facilitate priority setting in health policy and planning. PMID:21736715

  16. Accessibility

    MedlinePlus

    ... www.nlm.nih.gov/medlineplus/accessibility.html MedlinePlus Accessibility To use the sharing features on this page, ... Subscribe to RSS Follow us Disclaimers Copyright Privacy Accessibility Quality Guidelines Viewers & Players MedlinePlus Connect for EHRs ...

  17. Institutions in transitioning peri-urban communities: spatial differences in groundwater access

    NASA Astrophysics Data System (ADS)

    Gomes, Sharlene L.; Hermans, Leon M.

    2016-05-01

    Urbanization creates challenges for water management in an evolving socio-economic context. This is particularly relevant in transitioning peri-urban areas like Khulna, Bangladesh where competing demands have put pressure on local groundwater resources. Users are unable to sufficiently meet their needs through existing institutions. These institutions provide the rules for service provision and act as guidelines for actors to resolve their water related issues. However, the evolving peri-urban context can produce fragmented institutional arrangements. For example in Khulna, water supply is based on urban and rural boundaries that has created water access issues for peri-urban communities. This has motivated local actors to manage their groundwater needs in various ways. General institutional theories are well developed in literature, yet little is known about institutions in transitioning peri-urban areas. Institutions that fail to adapt to changing dynamics run the risk of becoming obsolete or counter-productive, hence the need for investigating institutional change mechanisms in this context. This paper examines peri-urban case studies from Khulna using the Institutional Analysis and Development framework to demonstrate how institutions have contributed to spatial differences in groundwater access with local actors investing in formal and informal institutional change as a means of accessing groundwater.

  18. Association between neighborhood need and spatial access to food stores and fast food restaurants in neighborhoods of Colonias

    PubMed Central

    Sharkey, Joseph R; Horel, Scott; Han, Daikwon; Huber, John C

    2009-01-01

    Objective To determine the extent to which neighborhood needs (socioeconomic deprivation and vehicle availability) are associated with two criteria of food environment access: 1) distance to the nearest food store and fast food restaurant and 2) coverage (number) of food stores and fast food restaurants within a specified network distance of neighborhood areas of colonias, using ground-truthed methods. Methods Data included locational points for 315 food stores and 204 fast food restaurants, and neighborhood characteristics from the 2000 U.S. Census for the 197 census block group (CBG) study area. Neighborhood deprivation and vehicle availability were calculated for each CBG. Minimum distance was determined by calculating network distance from the population-weighted center of each CBG to the nearest supercenter, supermarket, grocery, convenience store, dollar store, mass merchandiser, and fast food restaurant. Coverage was determined by calculating the number of each type of food store and fast food restaurant within a network distance of 1, 3, and 5 miles of each population-weighted CBG center. Neighborhood need and access were examined using Spearman ranked correlations, spatial autocorrelation, and multivariate regression models that adjusted for population density. Results Overall, neighborhoods had best access to convenience stores, fast food restaurants, and dollar stores. After adjusting for population density, residents in neighborhoods with increased deprivation had to travel a significantly greater distance to the nearest supercenter or supermarket, grocery store, mass merchandiser, dollar store, and pharmacy for food items. The results were quite different for association of need with the number of stores within 1 mile. Deprivation was only associated with fast food restaurants; greater deprivation was associated with fewer fast food restaurants within 1 mile. CBG with greater lack of vehicle availability had slightly better access to more supercenters

  19. Creating widely accessible spatial interfaces: mobile VR for managing persistent pain.

    PubMed

    Schroeder, David; Korsakov, Fedor; Jolton, Joseph; Keefe, Francis J; Haley, Alex; Keefe, Daniel F

    2013-01-01

    Using widely accessible VR technologies, researchers have implemented a series of multimodal spatial interfaces and virtual environments. The results demonstrate the degree to which we can now use low-cost (for example, mobile-phone based) VR environments to create rich virtual experiences involving motion sensing, physiological inputs, stereoscopic imagery, sound, and haptic feedback. Adapting spatial interfaces to these new platforms can open up exciting application areas for VR. In this case, the application area was in-home VR therapy for patients suffering from persistent pain (for example, arthritis and cancer pain). For such therapy to be successful, a rich spatial interface and rich visual aesthetic are particularly important. So, an interdisciplinary team with expertise in technology, design, meditation, and the psychology of pain collaborated to iteratively develop and evaluate several prototype systems. The video at http://youtu.be/mMPE7itReds demonstrates how the sine wave fitting responds to walking motions, for a walking-in-place application. PMID:24807994

  20. Using Python Scripting and Web Frameworks to Access Spatial and Temporal Data via KML

    NASA Astrophysics Data System (ADS)

    Erickson, T. A.; Koziol, B. W.

    2010-12-01

    Ever increasing volumes of spatial and temporal data about our world are being made available for download by various organizations. However, the data formats used are generally well-suited for storing large volumes of data but are not directly usable without specialized software. Also in recent years, there has been a wide adoption of easy-to-use virtual globe browsers (such as Google Earth) for viewing spatial and temporal datasets, but these applications cannot directly work with many large datasets due to the formats and/or the size of the datasets. This work presents several examples of Python-based data systems for accessing, filtering, and transforming large and complex spatial and temporal datasets into KML, an Open Geospatial Consortium (OGC) standard used for visualization and annotation of two-dimensional and three-dimensional data. Precipitable water forecasted by the NCEP Global Forecast System (GFS) model. Soil moisture content for December 2024 predicted by an IPCC model (GFDL R30).

  1. Passive background correction method for spatially resolved detection

    DOEpatents

    Schmitt, Randal L.; Hargis, Jr., Philip J.

    2011-05-10

    A method for passive background correction during spatially or angularly resolved detection of emission that is based on the simultaneous acquisition of both the passive background spectrum and the spectrum of the target of interest.

  2. Estimating spatial accessibility to facilities on the regional scale: an extended commuting-based interaction potential model

    PubMed Central

    2011-01-01

    Background There is growing interest in the study of the relationships between individual health-related behaviours (e.g. food intake and physical activity) and measurements of spatial accessibility to the associated facilities (e.g. food outlets and sport facilities). The aim of this study is to propose measurements of spatial accessibility to facilities on the regional scale, using aggregated data. We first used a potential accessibility model that partly makes it possible to overcome the limitations of the most frequently used indices such as the count of opportunities within a given neighbourhood. We then propose an extended model in order to take into account both home and work-based accessibility for a commuting population. Results Potential accessibility estimation provides a very different picture of the accessibility levels experienced by the population than the more classical "number of opportunities per census tract" index. The extended model for commuters increases the overall accessibility levels but this increase differs according to the urbanisation level. Strongest increases are observed in some rural municipalities with initial low accessibility levels. Distance to major urban poles seems to play an essential role. Conclusions Accessibility is a multi-dimensional concept that should integrate some aspects of travel behaviour. Our work supports the evidence that the choice of appropriate accessibility indices including both residential and non-residential environmental features is necessary. Such models have potential implications for providing relevant information to policy-makers in the field of public health. PMID:21219597

  3. Spatial econometrics functions in R: Classes and methods

    NASA Astrophysics Data System (ADS)

    Bivand, Roger

    Placing spatial econometrics and more generally spatial statistics in the context of an extensible data analysis environment such as R exposes similarities and differences between traditions of analysis. This can be fruitful, and is explored here in relation to prediction and other methods usually applied to fitted models in R. Objects in R may be assigned a class attribute, including fitted model objects. Such fitted model objects may be provided with methods allowing them to be displayed, compared, and used for prediction, and it is of interest to see whether fitted spatial models can be treated in the same way.

  4. Spatial Release From Masking in Simulated Cochlear Implant Users With and Without Access to Low-Frequency Acoustic Hearing

    PubMed Central

    Dietz, Mathias; Hohmann, Volker; Jürgens, Tim

    2015-01-01

    For normal-hearing listeners, speech intelligibility improves if speech and noise are spatially separated. While this spatial release from masking has already been quantified in normal-hearing listeners in many studies, it is less clear how spatial release from masking changes in cochlear implant listeners with and without access to low-frequency acoustic hearing. Spatial release from masking depends on differences in access to speech cues due to hearing status and hearing device. To investigate the influence of these factors on speech intelligibility, the present study measured speech reception thresholds in spatially separated speech and noise for 10 different listener types. A vocoder was used to simulate cochlear implant processing and low-frequency filtering was used to simulate residual low-frequency hearing. These forms of processing were combined to simulate cochlear implant listening, listening based on low-frequency residual hearing, and combinations thereof. Simulated cochlear implant users with additional low-frequency acoustic hearing showed better speech intelligibility in noise than simulated cochlear implant users without acoustic hearing and had access to more spatial speech cues (e.g., higher binaural squelch). Cochlear implant listener types showed higher spatial release from masking with bilateral access to low-frequency acoustic hearing than without. A binaural speech intelligibility model with normal binaural processing showed overall good agreement with measured speech reception thresholds, spatial release from masking, and spatial speech cues. This indicates that differences in speech cues available to listener types are sufficient to explain the changes of spatial release from masking across these simulated listener types. PMID:26721918

  5. Spatial Release From Masking in Simulated Cochlear Implant Users With and Without Access to Low-Frequency Acoustic Hearing.

    PubMed

    Williges, Ben; Dietz, Mathias; Hohmann, Volker; Jürgens, Tim

    2015-01-01

    For normal-hearing listeners, speech intelligibility improves if speech and noise are spatially separated. While this spatial release from masking has already been quantified in normal-hearing listeners in many studies, it is less clear how spatial release from masking changes in cochlear implant listeners with and without access to low-frequency acoustic hearing. Spatial release from masking depends on differences in access to speech cues due to hearing status and hearing device. To investigate the influence of these factors on speech intelligibility, the present study measured speech reception thresholds in spatially separated speech and noise for 10 different listener types. A vocoder was used to simulate cochlear implant processing and low-frequency filtering was used to simulate residual low-frequency hearing. These forms of processing were combined to simulate cochlear implant listening, listening based on low-frequency residual hearing, and combinations thereof. Simulated cochlear implant users with additional low-frequency acoustic hearing showed better speech intelligibility in noise than simulated cochlear implant users without acoustic hearing and had access to more spatial speech cues (e.g., higher binaural squelch). Cochlear implant listener types showed higher spatial release from masking with bilateral access to low-frequency acoustic hearing than without. A binaural speech intelligibility model with normal binaural processing showed overall good agreement with measured speech reception thresholds, spatial release from masking, and spatial speech cues. This indicates that differences in speech cues available to listener types are sufficient to explain the changes of spatial release from masking across these simulated listener types. PMID:26721918

  6. Evaluation of AMOEBA: a spectral-spatial classification method

    USGS Publications Warehouse

    Jenson, Susan K.; Loveland, Thomas R.; Bryant, J.

    1982-01-01

    Muitispectral remotely sensed images have been treated as arbitrary multivariate spectral data for purposes of clustering and classifying. However, the spatial properties of image data can also be exploited. AMOEBA is a clustering and classification method that is based on a spatially derived model for image data. In an evaluation test, Landsat data were classified with both AMOEBA and a widely used spectral classifier. The test showed that irrigated crop types can be classified as accurately with the AMOEBA method as with the generally used spectral method ISOCLS; the AMOEBA method, however, requires less computer time.

  7. [Ectopic parathyroid glands. Imaging methods and surgical access].

    PubMed

    Fialová, M; Adámková, J; Adámek, S; Libánský, P; Kubinyi, J

    2014-08-01

    We discuss the benefits of imaging methods in localizing ectopic parathyroid glands in patients with primary hyperparathyroidism. The ectopic localizations are discussed within the context of the orthotopic norm. In the sample of 123 patients, a 23% rate of ectopic parathyroid glands was detected. Three selected case studies are presented, supporting the benefit of SPECT/CT imaging in terms of surgical access strategy selection. PMID:25230388

  8. Rapid simulation of spatial epidemics: a spectral method.

    PubMed

    Brand, Samuel P C; Tildesley, Michael J; Keeling, Matthew J

    2015-04-01

    Spatial structure and hence the spatial position of host populations plays a vital role in the spread of infection. In the majority of situations, it is only possible to predict the spatial spread of infection using simulation models, which can be computationally demanding especially for large population sizes. Here we develop an approximation method that vastly reduces this computational burden. We assume that the transmission rates between individuals or sub-populations are determined by a spatial transmission kernel. This kernel is assumed to be isotropic, such that the transmission rate is simply a function of the distance between susceptible and infectious individuals; as such this provides the ideal mechanism for modelling localised transmission in a spatial environment. We show that the spatial force of infection acting on all susceptibles can be represented as a spatial convolution between the transmission kernel and a spatially extended 'image' of the infection state. This representation allows the rapid calculation of stochastic rates of infection using fast-Fourier transform (FFT) routines, which greatly improves the computational efficiency of spatial simulations. We demonstrate the efficiency and accuracy of this fast spectral rate recalculation (FSR) method with two examples: an idealised scenario simulating an SIR-type epidemic outbreak amongst N habitats distributed across a two-dimensional plane; the spread of infection between US cattle farms, illustrating that the FSR method makes continental-scale outbreak forecasting feasible with desktop processing power. The latter model demonstrates which areas of the US are at consistently high risk for cattle-infections, although predictions of epidemic size are highly dependent on assumptions about the tail of the transmission kernel. PMID:25659478

  9. Analytical resource assessment method for continuous (unconventional) oil and gas accumulations - The "ACCESS" Method

    USGS Publications Warehouse

    Crovelli, Robert A.; revised by Charpentier, Ronald R.

    2012-01-01

    The U.S. Geological Survey (USGS) periodically assesses petroleum resources of areas within the United States and the world. The purpose of this report is to explain the development of an analytic probabilistic method and spreadsheet software system called Analytic Cell-Based Continuous Energy Spreadsheet System (ACCESS). The ACCESS method is based upon mathematical equations derived from probability theory. The ACCESS spreadsheet can be used to calculate estimates of the undeveloped oil, gas, and NGL (natural gas liquids) resources in a continuous-type assessment unit. An assessment unit is a mappable volume of rock in a total petroleum system. In this report, the geologic assessment model is defined first, the analytic probabilistic method is described second, and the spreadsheet ACCESS is described third. In this revised version of Open-File Report 00-044 , the text has been updated to reflect modifications that were made to the ACCESS program. Two versions of the program are added as appendixes.

  10. Methods for Data-based Delineation of Spatial Regions

    SciTech Connect

    Wilson, John E.

    2012-10-01

    In data analysis, it is often useful to delineate or segregate areas of interest from the general population of data in order to concentrate further analysis efforts on smaller areas. Three methods are presented here for automatically generating polygons around spatial data of interest. Each method addresses a distinct data type. These methods were developed for and implemented in the sample planning tool called Visual Sample Plan (VSP). Method A is used to delineate areas of elevated values in a rectangular grid of data (raster). The data used for this method are spatially related. Although VSP uses data from a kriging process for this method, it will work for any type of data that is spatially coherent and appears on a regular grid. Method B is used to surround areas of interest characterized by individual data points that are congregated within a certain distance of each other. Areas where data are “clumped” together spatially will be delineated. Method C is used to recreate the original boundary in a raster of data that separated data values from non-values. This is useful when a rectangular raster of data contains non-values (missing data) that indicate they were outside of some original boundary. If the original boundary is not delivered with the raster, this method will approximate the original boundary.

  11. An incremental database access method for autonomous interoperable databases

    NASA Technical Reports Server (NTRS)

    Roussopoulos, Nicholas; Sellis, Timos

    1994-01-01

    We investigated a number of design and performance issues of interoperable database management systems (DBMS's). The major results of our investigation were obtained in the areas of client-server database architectures for heterogeneous DBMS's, incremental computation models, buffer management techniques, and query optimization. We finished a prototype of an advanced client-server workstation-based DBMS which allows access to multiple heterogeneous commercial DBMS's. Experiments and simulations were then run to compare its performance with the standard client-server architectures. The focus of this research was on adaptive optimization methods of heterogeneous database systems. Adaptive buffer management accounts for the random and object-oriented access methods for which no known characterization of the access patterns exists. Adaptive query optimization means that value distributions and selectives, which play the most significant role in query plan evaluation, are continuously refined to reflect the actual values as opposed to static ones that are computed off-line. Query feedback is a concept that was first introduced to the literature by our group. We employed query feedback for both adaptive buffer management and for computing value distributions and selectivities. For adaptive buffer management, we use the page faults of prior executions to achieve more 'informed' management decisions. For the estimation of the distributions of the selectivities, we use curve-fitting techniques, such as least squares and splines, for regressing on these values.

  12. Damping filter method for obtaining spatially localized solutions.

    PubMed

    Teramura, Toshiki; Toh, Sadayoshi

    2014-05-01

    Spatially localized structures are key components of turbulence and other spatiotemporally chaotic systems. From a dynamical systems viewpoint, it is desirable to obtain corresponding exact solutions, though their existence is not guaranteed. A damping filter method is introduced to obtain variously localized solutions and adapted in two typical cases. This method introduces a spatially selective damping effect to make a good guess at the exact solution, and we can obtain an exact solution through a continuation with the damping amplitude. The first target is a steady solution to the Swift-Hohenberg equation, which is a representative of bistable systems in which localized solutions coexist and a model for spanwise-localized cases. Not only solutions belonging to the well-known snaking branches but also those belonging to isolated branches known as "isolas" are found with continuation paths between them in phase space extended with the damping amplitude. This indicates that this spatially selective excitation mechanism has an advantage in searching spatially localized solutions. The second target is a spatially localized traveling-wave solution to the Kuramoto-Sivashinsky equation, which is a model for streamwise-localized cases. Since the spatially selective damping effect breaks Galilean and translational invariances, the propagation velocity cannot be determined uniquely while the damping is active, and a singularity arises when these invariances are recovered. We demonstrate that this singularity can be avoided by imposing a simple condition, and a localized traveling-wave solution is obtained with a specific propagation speed. PMID:25353864

  13. Method and Apparatus for Improved Spatial Light Modulation

    NASA Technical Reports Server (NTRS)

    Soutar, Colin (Inventor); Juday, Richard D. (Inventor)

    2000-01-01

    A method and apparatus for modulating a light beam in an optical processing system is described. Preferably, an electrically-controlled polarizer unit and/or an analyzer unit are utilized in combination with a spatial light modulator and a controller. Preferably, the spatial light modulator comprises a pixelated birefringent medium such as a liquid crystal video display. The combination of the electrically controlled polarizer unit and analyzer unit make it simple and fast to reconfigure the modulation described by the Jones matrix of the spatial light modulator. A particular optical processing objective is provided to the controller. The controller performs calculations and supplies control signals to the polarizer unit, the analyzer unit, and the spatial light modulator in order to obtain the optical processing objective.

  14. Method and Apparatus for Improved Spatial Light Modulation

    NASA Technical Reports Server (NTRS)

    Colin, Soutar (Inventor); Juday, Richard D. (Inventor)

    1999-01-01

    A method and apparatus for modulating a light beam in an optical processing system is described. Preferably, an electrically-controlled polarizer unit and/or an analyzer unit are utilized in combination with a spatial light modulator and a controller. Preferably, the spatial light modulator comprises a pixelated birefringent medium such as a liquid crystal video display. The combination of the electrically controlled polarizer unit and analyzer unit make it simple and fast to reconfigure the modulation described by the Jones matrix of the spatial light modulator. A particular optical processing objective is provided to the controller. The controller performs calculations and supplies control signals to the polarizer unit, the analyzer unit, and the spatial light modulator in order to obtain die optical processing objective.

  15. Nanotube structures, methods of making nanotube structures, and methods of accessing intracellular space

    DOEpatents

    VanDersarl, Jules J.; Xu, Alexander M.; Melosh, Nicholas A.; Tayebi, Noureddine

    2016-02-23

    In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, embodiments of the present disclosure, in one aspect, relate to methods of making a structure including nanotubes, a structure including nanotubes, methods of delivering a fluid to a cell, methods of removing a fluid to a cell, methods of accessing intracellular space, and the like.

  16. A suite of methods for representing activity space in a healthcare accessibility study

    PubMed Central

    Sherman, Jill E; Spencer, John; Preisser, John S; Gesler, Wilbert M; Arcury, Thomas A

    2005-01-01

    Background "Activity space" has been used to examine how people's habitual movements interact with their environment, and can be used to examine accessibility to healthcare opportunities. Traditionally, the standard deviational ellipse (SDE), a Euclidean measure, has been used to represent activity space. We describe the construction and application of the SDE at one and two standard deviations, and three additional network-based measures of activity space using common tools in GIS: the road network buffer (RNB), the 30-minute standard travel time polygon (STT), and the relative travel time polygon (RTT). We compare the theoretical and methodological assumptions of each measure, and evaluate the measures by examining access to primary care services, using data from western North Carolina. Results Individual accessibility is defined as the availability of healthcare opportunities within that individual's activity space. Access is influenced by the shape and area of an individual's activity space, the spatial distribution of opportunities, and by the spatial structures that constrain and direct movement through space; the shape and area of the activity space is partly a product of how it is conceptualized and measured. Network-derived measures improve upon the SDE by incorporating the spatial structures (roads) that channel movement. The area of the STT is primarily influenced by the location of a respondent's residence within the road network hierarchy, with residents living near primary roads having the largest activity spaces. The RNB was most descriptive of actual opportunities and can be used to examine bypassing. The area of the RTT had the strongest correlation with a healthcare destination being located inside the activity space. Conclusion The availability of geospatial technologies and data create multiple options for representing and operationalizing the construct of activity space. Each approach has its strengths and limitations, and presents a different

  17. Direct Two-Dimensional Access to the Spatial Location of Covert Attention in Macaque Prefrontal Cortex.

    PubMed

    Astrand, Elaine; Wardak, Claire; Baraduc, Pierre; Ben Hamed, Suliann

    2016-07-11

    Direct access to motor cortical information now enables tetraplegic patients to precisely control neuroprostheses and recover some autonomy. In contrast, explicit access to higher cortical cognitive functions, such as covert attention, has been missing. Indeed, this cognitive information, known only to the subject, can solely be inferred by an observer from the subject's overt behavior. Here, we present direct two-dimensional real-time access to where monkeys are covertly paying attention, using machine-learning decoding methods applied to their ongoing prefrontal cortical activity. Decoded attention was highly predictive of overt behavior in a cued target-detection task. Indeed, monkeys had a higher probability of detecting a visual stimulus as the distance between decoded attention and stimulus location decreased. This was true whether the visual stimulus was presented at the cued target location or at another distractor location. In error trials, in which the animals failed to detect the cued target stimulus, both the locations of attention and visual cue were misencoded. This misencoding coincided with a specific state of the prefrontal cortical population in which the shared variability between its different neurons (or noise correlations) was high, even before trial onset. This observation strongly suggests a functional link between high noise-correlation states and attentional failure. Overall, this real-time access to the attentional spotlight, as well as the identification of a neural signature of attentional lapses, open new perspectives both to the study of the neural bases of attention and to the remediation or enhancement of the attentional function using neurofeedback. PMID:27238280

  18. Daily access to sucrose impairs aspects of spatial memory tasks reliant on pattern separation and neural proliferation in rats.

    PubMed

    Reichelt, Amy C; Morris, Margaret J; Westbrook, Reginald Frederick

    2016-07-01

    High sugar diets reduce hippocampal neurogenesis, which is required for minimizing interference between memories, a process that involves "pattern separation." We provided rats with 2 h daily access to a sucrose solution for 28 d and assessed their performance on a spatial memory task. Sucrose consuming rats discriminated between objects in novel and familiar locations when there was a large spatial separation between the objects, but not when the separation was smaller. Neuroproliferation markers in the dentate gyrus of the sucrose-consuming rats were reduced relative to controls. Thus, sucrose consumption impaired aspects of spatial memory and reduced hippocampal neuroproliferation. PMID:27317199

  19. Examination of How Neighborhood Definition Influences Measurements of Youths' Access to Tobacco Retailers: A Methodological Note on Spatial Misclassification

    PubMed Central

    Duncan, Dustin T.; Kawachi, Ichiro; Subramanian, S.V.; Aldstadt, Jared; Melly, Steven J.; Williams, David R.

    2014-01-01

    Measurements of neighborhood exposures likely vary depending on the definition of “neighborhood” selected. This study examined the extent to which neighborhood definition influences findings regarding spatial accessibility to tobacco retailers among youth. We defined spatial accessibility to tobacco retailers (i.e., tobacco retail density, closest tobacco retailer, and average distance to the closest 5 tobacco retailers) on the basis of circular and network buffers of 400 m and 800 m, census block groups, and census tracts by using residential addresses from the 2008 Boston Youth Survey Geospatial Dataset (n = 1,292). Friedman tests (to compare overall differences in neighborhood definitions) were applied. There were differences in measurements of youths' access to tobacco retailers according to the selected neighborhood definitions, and these were marked for the 2 spatial proximity measures (both P < 0.01 for all differences). For example, the median average distance to the closest 5 tobacco retailers was 381.50 m when using specific home addresses, 414.00 m when using census block groups, and 482.50 m when using census tracts, illustrating how neighborhood definition influences the measurement of spatial accessibility to tobacco retailers. These analyses suggest that, whenever possible, egocentric neighborhood definitions should be used. The use of larger administrative neighborhood definitions can bias exposure estimates for proximity measures. PMID:24148710

  20. Daily Access to Sucrose Impairs Aspects of Spatial Memory Tasks Reliant on Pattern Separation and Neural Proliferation in Rats

    ERIC Educational Resources Information Center

    Reichelt, Amy C.; Morris, Margaret J.; Westbrook, Reginald Frederick

    2016-01-01

    High sugar diets reduce hippocampal neurogenesis, which is required for minimizing interference between memories, a process that involves "pattern separation." We provided rats with 2 h daily access to a sucrose solution for 28 d and assessed their performance on a spatial memory task. Sucrose consuming rats discriminated between objects…

  1. ViSA: A Neurodynamic Model for Visuo-Spatial Working Memory, Attentional Blink, and Conscious Access

    ERIC Educational Resources Information Center

    Simione, Luca; Raffone, Antonino; Wolters, Gezinus; Salmas, Paola; Nakatani, Chie; Belardinelli, Marta Olivetti; van Leeuwen, Cees

    2012-01-01

    Two separate lines of study have clarified the role of selectivity in conscious access to visual information. Both involve presenting multiple targets and distracters: one "simultaneously" in a spatially distributed fashion, the other "sequentially" at a single location. To understand their findings in a unified framework, we propose a…

  2. Access to Multidisciplinary and Spatial Data through the US Geological Survey

    NASA Astrophysics Data System (ADS)

    Rossmeissl, H. J.; Morton, J.

    2001-05-01

    The USGS serves the Nation by providing reliable scientific information to: describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life. The USGS stands as the sole science agency for the Department of the Interior. It is sought out by thousands of partners and customers for its natural science expertise and its vast earth and biological data holdings. USGS science provides comprehensive, high-quality, and timely scientific information to decision makers and the public. The information holdings of the USGS offer an amazing gateway to rich data bases, manipulatable maps, newly acquired satellite images, real-time information, and a wealth of reports spanning more than a century of science. The growing global population lives in an information age that is becoming incredibly complex. Scientific information is increasingly essential to an ever-widening--and demanding--customer base. This paper focuses on the activities underway at the USGS to make our multididisciplinary and spatial data more accessible to our users by utilizing new technologies and working through partnerships with other agencies and the private sector. Projects including the National Atlas of the United States of America, the Microsoft TerraServer, GeoMAC, and other interactive capabilities will be discussed. More and more, USGS information is available to all users over the internet in real-time, using interactive technologies, or downloadable on CD-ROM.

  3. Spatial distribution and accessibility to public sector tertiary care teaching hospitals in Karachi: A Geographic Information Systems application.

    PubMed

    Shaikh, Masood Ali; Ali, Mir Shabbar

    2016-07-01

    Optimal utilization of specialized curative healthcare services is contingent on spatial access to tertiary-care hospitals by the targeted population. The objectives of this study were to determine the spatial distribution of public sector tertiary-care teaching hospitals in Karachi, and to use GIS and network analysis for modeling the accessibility to these hospitals for Karachi residents. Maps of three, six, and nine kilometer buffers were created around the five selected hospitals to determine which towns of Karachi are either entirely or partially covered/accessible. Most of the towns in Karachi were covered either partially or completely by the three buffers and service areas of 3,6, and 9 kilometers around the five selected hospitals. This study highlights the limitations of using publicly available data for road network, and the need for creating and making available in public domain, comprehensive road network vector dataset in conjunction with population breakdowns by administrative subdivisions. PMID:27427142

  4. Hydrological model uncertainty due to spatial evapotranspiration estimation methods

    NASA Astrophysics Data System (ADS)

    Yu, Xuan; Lamačová, Anna; Duffy, Christopher; Krám, Pavel; Hruška, Jakub

    2016-05-01

    Evapotranspiration (ET) continues to be a difficult process to estimate in seasonal and long-term water balances in catchment models. Approaches to estimate ET typically use vegetation parameters (e.g., leaf area index [LAI], interception capacity) obtained from field observation, remote sensing data, national or global land cover products, and/or simulated by ecosystem models. In this study we attempt to quantify the uncertainty that spatial evapotranspiration estimation introduces into hydrological simulations when the age of the forest is not precisely known. The Penn State Integrated Hydrologic Model (PIHM) was implemented for the Lysina headwater catchment, located 50°03‧N, 12°40‧E in the western part of the Czech Republic. The spatial forest patterns were digitized from forest age maps made available by the Czech Forest Administration. Two ET methods were implemented in the catchment model: the Biome-BGC forest growth sub-model (1-way coupled to PIHM) and with the fixed-seasonal LAI method. From these two approaches simulation scenarios were developed. We combined the estimated spatial forest age maps and two ET estimation methods to drive PIHM. A set of spatial hydrologic regime and streamflow regime indices were calculated from the modeling results for each method. Intercomparison of the hydrological responses to the spatial vegetation patterns suggested considerable variation in soil moisture and recharge and a small uncertainty in the groundwater table elevation and streamflow. The hydrologic modeling with ET estimated by Biome-BGC generated less uncertainty due to the plant physiology-based method. The implication of this research is that overall hydrologic variability induced by uncertain management practices was reduced by implementing vegetation models in the catchment models.

  5. Method and apparatus for granting processors access to a resource

    DOEpatents

    Blumrich, Matthias A.; Salapura, Valentina

    2010-03-16

    An apparatus and method for granting one or more requesting entities access to a resource in a predetermined time interval. The apparatus includes a first circuit receiving one or more request signals, and implementing logic for assigning a priority to the one or more request signals, and, generating a set of first_request signals based on the priorities assigned. One or more priority select circuits for receiving the set of first_request signals and generating corresponding one or more fixed grant signals representing one or more highest priority request signals when asserted during the predetermined time interval. A second circuit device receives the one or more fixed grant signals generates one or more grant signals associated with one or more highest priority request signals assigned, the grant signals for enabling one or more respective requesting entities access to the resource in the predetermined time interval, wherein the priority assigned to the one or more request signals changes each successive predetermined time interval. In one embodiment, the assigned priority is based on a numerical pattern, the first circuit changing the numerical pattern with respect to the first_request signals generated at each successive predetermined time interval.

  6. Super Spatial Resolution (SSR) method for scintigraphic imaging

    NASA Astrophysics Data System (ADS)

    Trinci, G.; Massari, R.; Scandellari, M.; Scopinaro, F.; Soluri, A.

    2011-01-01

    This work describes an innovative patented Super Spatial Resolution (SSR) method applied to scintigraphic devices. The aim of Super Resolution (SR) techniques is to enhance the resolution of an imaging system, using information from several images. SR reconstruction may be considered as a second generation problem of Image Restoration. It combines several slightly different Low Resolution (LR) images to obtain a High Resolution (HR) image. SR techniques are, widely, described in scientific literature mainly for applications in video communication, object recognition and image compression. In this paper we focus to apply the SR task to the scintigraphic imaging. Specifically, it is described as a patented method that uses a High Resolution Scintigraphic Camera (HRSC) to collect and process a set of scintigraphic images, in view of obtaining a very high resolution image. The HRSC device, which is currently used in Medical Imaging, is based on a parallel square holes collimator and on a Hamamatsu H8500 Position Sensitive Photomultiplier Tubes (PSPMT). The SSR method is applied to the synthetic images of three different phantoms, to verify the effective spatial resolution values. The results confirm that it is possible to achieve optimal spatial resolution values at different depths, useful in small object and small animal imaging. Our study confirms the feasibility of a very high resolution system in scintigraphic imaging and the possibility to have gamma cameras using the SSR method, to perform clinical applications on patients.

  7. ViSA: a neurodynamic model for visuo-spatial working memory, attentional blink, and conscious access.

    PubMed

    Simione, Luca; Raffone, Antonino; Wolters, Gezinus; Salmas, Paola; Nakatani, Chie; Belardinelli, Marta Olivetti; van Leeuwen, Cees

    2012-10-01

    Two separate lines of study have clarified the role of selectivity in conscious access to visual information. Both involve presenting multiple targets and distracters: one simultaneously in a spatially distributed fashion, the other sequentially at a single location. To understand their findings in a unified framework, we propose a neurodynamic model for Visual Selection and Awareness (ViSA). ViSA supports the view that neural representations for conscious access and visuo-spatial working memory are globally distributed and are based on recurrent interactions between perceptual and access control processors. Its flexible global workspace mechanisms enable a unitary account of a broad range of effects: It accounts for the limited storage capacity of visuo-spatial working memory, attentional cueing, and efficient selection with multi-object displays, as well as for the attentional blink and associated sparing and masking effects. In particular, the speed of consolidation for storage in visuo-spatial working memory in ViSA is not fixed but depends adaptively on the input and recurrent signaling. Slowing down of consolidation due to weak bottom-up and recurrent input as a result of brief presentation and masking leads to the attentional blink. Thus, ViSA goes beyond earlier 2-stage and neuronal global workspace accounts of conscious processing limitations. PMID:22823385

  8. Spatial access to sterile syringes and the odds of injecting with an unsterile syringe among injectors: a longitudinal multilevel study.

    PubMed

    Cooper, Hannah; Des Jarlais, Don; Ross, Zev; Tempalski, Barbara; Bossak, Brian H; Friedman, Samuel R

    2012-08-01

    Despite the 2010 repeal of the ban on spending federal monies to fund syringe exchange programs (SEPs) in the U.S.A., these interventions--and specifically SEP site locations--remain controversial. To further inform discussions about the location of SEP sites, this longitudinal multilevel study investigates the relationship between spatial access to sterile syringes distributed by SEPs in New York City (NYC) United Hospital Fund (UHF) districts and injecting with an unsterile syringe among injectors over time (1995-2006). Annual measures of spatial access to syringes in each UHF district (N = 42) were created using data on SEP site locations and site-specific syringe distribution data. Individual-level data on unsterile injecting among injectors (N = 4,067) living in these districts, and on individual-level covariates, were drawn from the Risk Factors study, an ongoing cross-sectional study of NYC drug users. We used multilevel models to explore the relationship of district-level access to syringes to the odds of injecting with an unsterile syringe in >75% of injection events in the past 6 months, and to test whether this relationship varied by district-level arrest rates (per 1,000 residents) for drug and drug paraphernalia possession. The relationship between district-level access to syringes and the odds of injecting with an unsterile syringe depended on district-level arrest rates. In districts with low baseline arrest rates, better syringe access was associated with a decline in the odds of frequently injecting with an unsterile syringe (AOR, 0.95). In districts with no baseline syringe access, higher arrest rates were associated with increased odds of frequently injecting with an unsterile syringe (AOR, 1.02) When both interventions were present, arrest rates eroded the protective effects of spatial access to syringes. Spatial access to syringes in small geographic areas appears to reduce the odds of injecting with an unsterile syringe among local

  9. Widely accessible method for superresolution fluorescence imaging of living systems.

    PubMed

    Dedecker, Peter; Mo, Gary C H; Dertinger, Thomas; Zhang, Jin

    2012-07-01

    Superresolution fluorescence microscopy overcomes the diffraction resolution barrier and allows the molecular intricacies of life to be revealed with greatly enhanced detail. However, many current superresolution techniques still face limitations and their implementation is typically associated with a steep learning curve. Patterned illumination-based superresolution techniques [e.g., stimulated emission depletion (STED), reversible optically-linear fluorescence transitions (RESOLFT), and saturated structured illumination microscopy (SSIM)] require specialized equipment, whereas single-molecule-based approaches [e.g., stochastic optical reconstruction microscopy (STORM), photo-activation localization microscopy (PALM), and fluorescence-PALM (F-PALM)] involve repetitive single-molecule localization, which requires its own set of expertise and is also temporally demanding. Here we present a superresolution fluorescence imaging method, photochromic stochastic optical fluctuation imaging (pcSOFI). In this method, irradiating a reversibly photoswitching fluorescent protein at an appropriate wavelength produces robust single-molecule intensity fluctuations, from which a superresolution picture can be extracted by a statistical analysis of the fluctuations in each pixel as a function of time, as previously demonstrated in SOFI. This method, which uses off-the-shelf equipment, genetically encodable labels, and simple and rapid data acquisition, is capable of providing two- to threefold-enhanced spatial resolution, significant background rejection, markedly improved contrast, and favorable temporal resolution in living cells. Furthermore, both 3D and multicolor imaging are readily achievable. Because of its ease of use and high performance, we anticipate that pcSOFI will prove an attractive approach for superresolution imaging. PMID:22711840

  10. Toward a Next Generation of Widely Accessible Spatial Interfaces: Mobile VR Environments for Patients with Persistent Pain

    PubMed Central

    Schroeder, David; Korsakov, Fedor; Jolton, Joseph; Keefe, Francis J.; Haley, Alex; Keefe, Daniel F.

    2015-01-01

    We present a series of multi-modal spatial interfaces and virtual environments that can be implemented with widely accessible virtual reality (VR) technologies. The results demonstrate and evaluate the new degree to which rich virtual experiences involving motion sensing, physiological inputs, stereoscopic imagery, sound, and haptic feedback can now be created using low-cost (e.g., mobile phone based) VR environments. Adapting spatial interfaces to these new platforms can open up exciting new application areas for VR. This is demonstrated through a series of prototype systems aimed at delivering in-home VR therapies to patients suffering from persistent pain conditions (e.g. arthritis pain, cancer pain). A rich spatial interface and visual aesthetic is particularly important for the success of these applications; thus an interdisciplinary team with expertise in technology, design, meditation, and the psychology of pain worked together to iteratively develop and evaluate the current prototypes. PMID:24807994

  11. Spatially-Anisotropic Parallel Adaptive Wavelet Collocation Method

    NASA Astrophysics Data System (ADS)

    Vasilyev, Oleg V.; Brown-Dymkoski, Eric

    2015-11-01

    Despite latest advancements in development of robust wavelet-based adaptive numerical methodologies to solve partial differential equations, they all suffer from two major ``curses'': 1) the reliance on rectangular domain and 2) the ``curse of anisotropy'' (i.e. homogeneous wavelet refinement and inability to have spatially varying aspect ratio of the mesh elements). The new method addresses both of these challenges by utilizing an adaptive anisotropic wavelet transform on curvilinear meshes that can be either algebraically prescribed or calculated on the fly using PDE-based mesh generation. In order to ensure accurate representation of spatial operators in physical space, an additional adaptation on spatial physical coordinates is also performed. It is important to note that when new nodes are added in computational space, the physical coordinates can be approximated by interpolation of the existing solution and additional local iterations to ensure that the solution of coordinate mapping PDEs is converged on the new mesh. In contrast to traditional mesh generation approaches, the cost of adding additional nodes is minimal, mainly due to localized nature of iterative mesh generation PDE solver requiring local iterations in the vicinity of newly introduced points. This work was supported by ONR MURI under grant N00014-11-1-069.

  12. Methods for spectral image analysis by exploiting spatial simplicity

    DOEpatents

    Keenan, Michael R.

    2010-05-25

    Several full-spectrum imaging techniques have been introduced in recent years that promise to provide rapid and comprehensive chemical characterization of complex samples. One of the remaining obstacles to adopting these techniques for routine use is the difficulty of reducing the vast quantities of raw spectral data to meaningful chemical information. Multivariate factor analysis techniques, such as Principal Component Analysis and Alternating Least Squares-based Multivariate Curve Resolution, have proven effective for extracting the essential chemical information from high dimensional spectral image data sets into a limited number of components that describe the spectral characteristics and spatial distributions of the chemical species comprising the sample. There are many cases, however, in which those constraints are not effective and where alternative approaches may provide new analytical insights. For many cases of practical importance, imaged samples are "simple" in the sense that they consist of relatively discrete chemical phases. That is, at any given location, only one or a few of the chemical species comprising the entire sample have non-zero concentrations. The methods of spectral image analysis of the present invention exploit this simplicity in the spatial domain to make the resulting factor models more realistic. Therefore, more physically accurate and interpretable spectral and abundance components can be extracted from spectral images that have spatially simple structure.

  13. Methods for spectral image analysis by exploiting spatial simplicity

    DOEpatents

    Keenan, Michael R.

    2010-11-23

    Several full-spectrum imaging techniques have been introduced in recent years that promise to provide rapid and comprehensive chemical characterization of complex samples. One of the remaining obstacles to adopting these techniques for routine use is the difficulty of reducing the vast quantities of raw spectral data to meaningful chemical information. Multivariate factor analysis techniques, such as Principal Component Analysis and Alternating Least Squares-based Multivariate Curve Resolution, have proven effective for extracting the essential chemical information from high dimensional spectral image data sets into a limited number of components that describe the spectral characteristics and spatial distributions of the chemical species comprising the sample. There are many cases, however, in which those constraints are not effective and where alternative approaches may provide new analytical insights. For many cases of practical importance, imaged samples are "simple" in the sense that they consist of relatively discrete chemical phases. That is, at any given location, only one or a few of the chemical species comprising the entire sample have non-zero concentrations. The methods of spectral image analysis of the present invention exploit this simplicity in the spatial domain to make the resulting factor models more realistic. Therefore, more physically accurate and interpretable spectral and abundance components can be extracted from spectral images that have spatially simple structure.

  14. Jacob's Interpretation Method Revisited: Accounting for 3-D Spatial Heterogeneity

    NASA Astrophysics Data System (ADS)

    Sanchez-Vila, X.; Riva, M.; Guadagnini, A.; Carrera, J.

    2005-12-01

    Traditional approaches to hydraulic test interpretation provide typically individual aquifer parameters, such as hydraulic conductivity (K) and storativity (S) values. The values obtained somehow incorporate some averaging values of aquifer heterogeneity, while the averaging functions are a direct consequence of the method of analysis employed. In recent years most work, casted in a stochastic framework, focused on the relationship between pumping rate and ensemble mean or variance of drawdown, thus having to pre-specify the parameters characterizing the underlying random spatial function. On the contrary, we contend that additional highly relevant information about heterogeneity can be obtained by looking to the spatial distribution of drawdown in individual realizations of the heterogeneous K field, without the need for invoking ergodic arguments. We present an analysis of the spatial distribution of time-dependent drawdown in a tridimensional aquifer produced by constant rate pumping in a fully penetrating well. The aquifer is considered of infinite extension in the x, y directions, and we assume no-flow boundaries in the aquifer top and bottom. The observation point is a fully penetrating piezometer. We consider an unknown spatial distribution of K(x,y,z), and using a perturbation expansion up to second order, we look at the late-time behavior of drawdown at any given observation vertical line. We conclude that: (1) at any given observation line the late-time behavior of drawdown would display a straight line in a drawdown versus log time plot, thus allowing the use of Jacob's method for test interpretation; (2) the slope of the straight line is the same for each observation line, thus providing a global average of K(x,y,z) through the aquifer; (3) the intercept point of the line in the same plot depends on location and is related to connectivity issues between the pumping and observation locations; (4) the intercept value is a weighted function of the local

  15. A random spatial sampling method in a rural developing nation

    PubMed Central

    2014-01-01

    Background Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. Methods We describe a stratified random sampling method using geographical information system (GIS) software and global positioning system (GPS) technology for application in a health survey in a rural region of Guatemala, as well as a qualitative study of the enumeration process. Results This method offers an alternative sampling technique that could reduce opportunities for bias in household selection compared to cluster methods. However, its use is subject to issues surrounding survey preparation, technological limitations and in-the-field household selection. Application of this method in remote areas will raise challenges surrounding the boundary delineation process, use and translation of satellite imagery between GIS and GPS, and household selection at each survey point in varying field conditions. This method favors household selection in denser urban areas and in new residential developments. Conclusions Random spatial sampling methodology can be used to survey a random sample of population in a remote region of a developing nation. Although this method should be further validated and compared with more established methods to determine its utility in social survey applications, it shows promise for use in developing nations with resource-challenged environments where detailed geographic and human census data are less available. PMID:24716473

  16. Spatial Access to Syringe Exchange Programs and Pharmacies Selling Over-the-Counter Syringes as Predictors of Drug Injectors' Use of Sterile Syringes

    PubMed Central

    Des Jarlais, Don C.; Ross, Zev; Tempalski, Barbara; Bossak, Brian; Friedman, Samuel R.

    2011-01-01

    Objectives. We examined relationships of spatial access to syringe exchange programs (SEPs) and pharmacies selling over-the-counter (OTC) syringes with New York City drug injectors’ harm reduction practices. Methods. Each year from 1995 to 2006, we measured the percentage of 42 city health districts’ surface area that was within 1 mile of an SEP or OTC pharmacy. We applied hierarchical generalized linear models to investigate relationships between these exposures and the odds that injectors (n = 4003) used a sterile syringe for at least 75% of injections in the past 6 months. Results. A 1-unit increase in the natural log of the percentage of a district's surface area within a mile of an SEP in 1995 was associated with a 26% increase in the odds of injecting with a sterile syringe; a 1-unit increase in this exposure over time increased these odds 23%. A 1-unit increase in the natural log of OTC pharmacy access improved these odds 15%. Conclusions. Greater spatial access to SEPs and OTC pharmacies improved injectors’ capacity to engage in harm reduction practices that reduce HIV and HCV transmission. PMID:21088267

  17. A broadband spectral inversion method for spatial heterodyne spectroscopy

    NASA Astrophysics Data System (ADS)

    Cai, Qisheng; Bin, Xiangli; Du, Shusong

    2014-11-01

    Spatial heterodyne spectroscopy (SHS) is a Fourier-transform spectroscopic technique with many advantages, such as high throughput, good robustness (no moving parts), and high resolving power. However, in the basic theory of SHS, the relationship between the wavenumber and the frequency of the interferogram is approximated to be linear. This approximation limits the spectral range of a spatial heterodyne spectrometer to a narrow band near the Littrow wavenumber. Several methods have been developed to extend the spectral range of the SHS. They use echelle gratings or tunable pilot mirrors to make a SHS instrument work at multiple narrow spectral bands near different Littrow wavenumbers. These solutions still utilize the linear relationship between the wavenumber and the frequency of the interferogram. But they need to separate different spectral bands, and this will increase the difficulty of post processing and the complexity of the SHS system. Here, we solve this problem from another perspective: making a SHS system work at one broad spectral band instead of multiple narrow spectral bands. As in a broad spectral range, the frequency of the interferogram will not be linear with respect to the wavenumber anymore. According to this non-linear relationship, we propose a broadband spectral inversion method based on the stationary phase theory. At first, we describe the principles and the basic characters of SHS. Then, the narrow band limitation is analyzed and the broadband spectral inversion method is elaborated. In the end, we present a parameter design example of the SHS system according to a given spectral range, and the effectiveness of this method is validated with a spectral simulation example. This broadband spectral inversion method can be applied to the existing SHS system without changing or inserting any moving components. This method retains the advantages of SHS and there is almost no increase in complexity for post processing.

  18. Quantitative methods in electroencephalography to access therapeutic response.

    PubMed

    Diniz, Roseane Costa; Fontenele, Andrea Martins Melo; Carmo, Luiza Helena Araújo do; Ribeiro, Aurea Celeste da Costa; Sales, Fábio Henrique Silva; Monteiro, Sally Cristina Moutinho; Sousa, Ana Karoline Ferreira de Castro

    2016-07-01

    Pharmacometrics or Quantitative Pharmacology aims to quantitatively analyze the interaction between drugs and patients whose tripod: pharmacokinetics, pharmacodynamics and disease monitoring to identify variability in drug response. Being the subject of central interest in the training of pharmacists, this work was out with a view to promoting this idea on methods to access the therapeutic response of drugs with central action. This paper discusses quantitative methods (Fast Fourier Transform, Magnitude Square Coherence, Conditional Entropy, Generalised Linear semi-canonical Correlation Analysis, Statistical Parametric Network and Mutual Information Function) used to evaluate the EEG signals obtained after administration regimen of drugs, the main findings and their clinical relevance, pointing it as a contribution to construction of different pharmaceutical practice. Peter Anderer et. al in 2000 showed the effect of 20mg of buspirone in 20 healthy subjects after 1, 2, 4, 6 and 8h after oral ingestion of the drug. The areas of increased power of the theta frequency occurred mainly in the temporo-occipital - parietal region. It has been shown by Sampaio et al., 2007 that the use of bromazepam, which allows the release of GABA (gamma amino butyric acid), an inhibitory neurotransmitter of the central nervous system could theoretically promote dissociation of cortical functional areas, a decrease of functional connectivity, a decrease of cognitive functions by means of smaller coherence (electrophysiological magnitude measured from the EEG by software) values. Ahmad Khodayari-Rostamabad et al. in 2015 talk that such a measure could be a useful clinical tool potentially to assess adverse effects of opioids and hence give rise to treatment guidelines. There was the relation between changes in pain intensity and brain sources (at maximum activity locations) during remifentanil infusion despite its potent analgesic effect. The statement of mathematical and computational

  19. Landscape-scale accessibility of livestock to tigers: implications of spatial grain for modeling predation risk to mitigate human-carnivore conflict.

    PubMed

    Miller, Jennifer R B; Jhala, Yadvendradev V; Jena, Jyotirmay; Schmitz, Oswald J

    2015-03-01

    Innovative conservation tools are greatly needed to reduce livelihood losses and wildlife declines resulting from human-carnivore conflict. Spatial risk modeling is an emerging method for assessing the spatial patterns of predator-prey interactions, with applications for mitigating carnivore attacks on livestock. Large carnivores that ambush prey attack and kill over small areas, requiring models at fine spatial grains to predict livestock depredation hot spots. To detect the best resolution for predicting where carnivores access livestock, we examined the spatial attributes associated with livestock killed by tigers in Kanha Tiger Reserve, India, using risk models generated at 20, 100, and 200-m spatial grains. We analyzed land-use, human presence, and vegetation structure variables at 138 kill sites and 439 random sites to identify key landscape attributes where livestock were vulnerable to tigers. Land-use and human presence variables contributed strongly to predation risk models, with most variables showing high relative importance (≥0.85) at all spatial grains. The risk of a tiger killing livestock increased near dense forests and near the boundary of the park core zone where human presence is restricted. Risk was nonlinearly related to human infrastructure and open vegetation, with the greatest risk occurring 1.2 km from roads, 1.1 km from villages, and 8.0 km from scrubland. Kill sites were characterized by denser, patchier, and more complex vegetation with lower visibility than random sites. Risk maps revealed high-risk hot spots inside of the core zone boundary and in several patches in the human-dominated buffer zone. Validation against known kills revealed predictive accuracy for only the 20 m model, the resolution best representing the kill stage of hunting for large carnivores that ambush prey, like the tiger. Results demonstrate that risk models developed at fine spatial grains can offer accurate guidance on landscape attributes livestock should

  20. Landscape-scale accessibility of livestock to tigers: implications of spatial grain for modeling predation risk to mitigate human–carnivore conflict

    PubMed Central

    Miller, Jennifer R B; Jhala, Yadvendradev V; Jena, Jyotirmay; Schmitz, Oswald J

    2015-01-01

    Innovative conservation tools are greatly needed to reduce livelihood losses and wildlife declines resulting from human–carnivore conflict. Spatial risk modeling is an emerging method for assessing the spatial patterns of predator–prey interactions, with applications for mitigating carnivore attacks on livestock. Large carnivores that ambush prey attack and kill over small areas, requiring models at fine spatial grains to predict livestock depredation hot spots. To detect the best resolution for predicting where carnivores access livestock, we examined the spatial attributes associated with livestock killed by tigers in Kanha Tiger Reserve, India, using risk models generated at 20, 100, and 200-m spatial grains. We analyzed land-use, human presence, and vegetation structure variables at 138 kill sites and 439 random sites to identify key landscape attributes where livestock were vulnerable to tigers. Land-use and human presence variables contributed strongly to predation risk models, with most variables showing high relative importance (≥0.85) at all spatial grains. The risk of a tiger killing livestock increased near dense forests and near the boundary of the park core zone where human presence is restricted. Risk was nonlinearly related to human infrastructure and open vegetation, with the greatest risk occurring 1.2 km from roads, 1.1 km from villages, and 8.0 km from scrubland. Kill sites were characterized by denser, patchier, and more complex vegetation with lower visibility than random sites. Risk maps revealed high-risk hot spots inside of the core zone boundary and in several patches in the human-dominated buffer zone. Validation against known kills revealed predictive accuracy for only the 20 m model, the resolution best representing the kill stage of hunting for large carnivores that ambush prey, like the tiger. Results demonstrate that risk models developed at fine spatial grains can offer accurate guidance on landscape attributes livestock

  1. A spatial shape constrained clustering method for mammographic mass segmentation.

    PubMed

    Lou, Jian-Yong; Yang, Xu-Lei; Cao, Ai-Ze

    2015-01-01

    A novel clustering method is proposed for mammographic mass segmentation on extracted regions of interest (ROIs) by using deterministic annealing incorporating circular shape function (DACF). The objective function reported in this study uses both intensity and spatial shape information, and the dominant dissimilarity measure is controlled by two weighting parameters. As a result, pixels having similar intensity information but located in different regions can be differentiated. Experimental results shows that, by using DACF, the mass segmentation results in digitized mammograms are improved with optimal mass boundaries, less number of noisy patches, and computational efficiency. An average probability of segmentation error of 7.18% for well-defined masses (or 8.06% for ill-defined masses) was obtained by using DACF on MiniMIAS database, with 5.86% (or 5.55%) and 6.14% (or 5.27%) improvements as compared to the standard DA and fuzzy c-means methods. PMID:25737739

  2. Real-time 2D spatially selective MRI experiments: Comparative analysis of optimal control design methods

    NASA Astrophysics Data System (ADS)

    Maximov, Ivan I.; Vinding, Mads S.; Tse, Desmond H. Y.; Nielsen, Niels Chr.; Shah, N. Jon

    2015-05-01

    There is an increasing need for development of advanced radio-frequency (RF) pulse techniques in modern magnetic resonance imaging (MRI) systems driven by recent advancements in ultra-high magnetic field systems, new parallel transmit/receive coil designs, and accessible powerful computational facilities. 2D spatially selective RF pulses are an example of advanced pulses that have many applications of clinical relevance, e.g., reduced field of view imaging, and MR spectroscopy. The 2D spatially selective RF pulses are mostly generated and optimised with numerical methods that can handle vast controls and multiple constraints. With this study we aim at demonstrating that numerical, optimal control (OC) algorithms are efficient for the design of 2D spatially selective MRI experiments, when robustness towards e.g. field inhomogeneity is in focus. We have chosen three popular OC algorithms; two which are gradient-based, concurrent methods using first- and second-order derivatives, respectively; and a third that belongs to the sequential, monotonically convergent family. We used two experimental models: a water phantom, and an in vivo human head. Taking into consideration the challenging experimental setup, our analysis suggests the use of the sequential, monotonic approach and the second-order gradient-based approach as computational speed, experimental robustness, and image quality is key. All algorithms used in this work were implemented in the MATLAB environment and are freely available to the MRI community.

  3. Real-time 2D spatially selective MRI experiments: Comparative analysis of optimal control design methods.

    PubMed

    Maximov, Ivan I; Vinding, Mads S; Tse, Desmond H Y; Nielsen, Niels Chr; Shah, N Jon

    2015-05-01

    There is an increasing need for development of advanced radio-frequency (RF) pulse techniques in modern magnetic resonance imaging (MRI) systems driven by recent advancements in ultra-high magnetic field systems, new parallel transmit/receive coil designs, and accessible powerful computational facilities. 2D spatially selective RF pulses are an example of advanced pulses that have many applications of clinical relevance, e.g., reduced field of view imaging, and MR spectroscopy. The 2D spatially selective RF pulses are mostly generated and optimised with numerical methods that can handle vast controls and multiple constraints. With this study we aim at demonstrating that numerical, optimal control (OC) algorithms are efficient for the design of 2D spatially selective MRI experiments, when robustness towards e.g. field inhomogeneity is in focus. We have chosen three popular OC algorithms; two which are gradient-based, concurrent methods using first- and second-order derivatives, respectively; and a third that belongs to the sequential, monotonically convergent family. We used two experimental models: a water phantom, and an in vivo human head. Taking into consideration the challenging experimental setup, our analysis suggests the use of the sequential, monotonic approach and the second-order gradient-based approach as computational speed, experimental robustness, and image quality is key. All algorithms used in this work were implemented in the MATLAB environment and are freely available to the MRI community. PMID:25863895

  4. Evaluating E-Learning Accessibility by Automated and Student-Centered Methods

    ERIC Educational Resources Information Center

    Kumar, Kari L.; Owston, Ron

    2016-01-01

    The use of learning technologies is becoming ubiquitous in higher education. As a result, there is a pressing need to develop methods to evaluate their accessibility to ensure that students do not encounter barriers to accessibility while engaging in e-learning. In this study, sample online units were evaluated for accessibility by automated tools…

  5. Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

  6. Numerical Weather Predictions Evaluation Using Spatial Verification Methods

    NASA Astrophysics Data System (ADS)

    Tegoulias, I.; Pytharoulis, I.; Kotsopoulos, S.; Kartsios, S.; Bampzelis, D.; Karacostas, T.

    2014-12-01

    During the last years high-resolution numerical weather prediction simulations have been used to examine meteorological events with increased convective activity. Traditional verification methods do not provide the desired level of information to evaluate those high-resolution simulations. To assess those limitations new spatial verification methods have been proposed. In the present study an attempt is made to estimate the ability of the WRF model (WRF -ARW ver3.5.1) to reproduce selected days with high convective activity during the year 2010 using those feature-based verification methods. Three model domains, covering Europe, the Mediterranean Sea and northern Africa (d01), the wider area of Greece (d02) and central Greece - Thessaly region (d03) are used at horizontal grid-spacings of 15km, 5km and 1km respectively. By alternating microphysics (Ferrier, WSM6, Goddard), boundary layer (YSU, MYJ) and cumulus convection (Kain-­-Fritsch, BMJ) schemes, a set of twelve model setups is obtained. The results of those simulations are evaluated against data obtained using a C-Band (5cm) radar located at the centre of the innermost domain. Spatial characteristics are well captured but with a variable time lag between simulation results and radar data. Acknowledgements: This research is co­financed by the European Union (European Regional Development Fund) and Greek national funds, through the action "COOPERATION 2011: Partnerships of Production and Research Institutions in Focused Research and Technology Sectors" (contract number 11SYN_8_1088 - DAPHNE) in the framework of the operational programme "Competitiveness and Entrepreneurship" and Regions in Transition (OPC II, NSRF 2007-­-2013).

  7. Spatial and Spectral Methods for Weed Detection and Localization

    NASA Astrophysics Data System (ADS)

    Vioix, Jean-Baptiste; Douzals, Jean-Paul; Truchetet, Frédéric; Assémat, Louis; Guillemin, Jean-Philippe

    2002-12-01

    This study concerns the detection and localization of weed patches in order to improve the knowledge on weed-crop competition. A remote control aircraft provided with a camera allowed to obtain low cost and repetitive information. Different processings were involved to detect weed patches using spatial then spectral methods. First, a shift of colorimetric base allowed to separate the soil and plant pixels. Then, a specific algorithm including Gabor filter was applied to detect crop rows on the vegetation image. Weed patches were then deduced from the comparison of vegetation and crop images. Finally, the development of a multispectral acquisition device is introduced. First results for the discrimination of weeds and crops using the spectral properties are shown from laboratory tests. Application of neural networks were mostly studied.

  8. Spatial-phase code-division multiple-access system with multiplexed Fourier holography switching for reconfigurable optical interconnection.

    PubMed

    Takasago, K; Takekawa, M; Shirakawa, A; Kannari, F

    2000-05-10

    A new, to our knowledge, space-variant optical interconnection system based on a spatial-phase code-division multiple-access technique with multiplexed Fourier holography is described. In this technique a signal beam is spread over wide spatial frequencies by an M-sequence pseudorandom phase code. At a receiver side a selected signal beam is properly decoded, and at the same time its spatial pattern is shaped with a Fourier hologram, which is recorded by light that is encoded with the same M-sequence phase mask as the desired signal beam and by light whose spatial beam pattern is shaped to a signal routing pattern. Using the multiplexed holography, we can simultaneously route multisignal flows into individually specified receiver elements. The routing pattern can also be varied by means of switching the encoding phase code or replacing the hologram. We demonstrated a proof-of-principle experiment with a doubly multiplexed hologram that enables simultaneous routing of two signal beams. Using a numerical model, we showed that the proposed scheme can manage more than 250 routing patterns for one signal flow with one multiplexed hologram at a signal-to-noise ratio of ~5. PMID:18345134

  9. An accessible method for teaching doctors about death certification.

    PubMed

    Walker, Sue; Rampatige, Rasika; Wainiqolo, Iris; Aumua, Audrey

    2012-01-01

    The World Health Organization (WHO) recommends that data on mortality in its member countries are collected utilising the Medical Certificate of Cause of Death published in the instruction volume of the ICD-10. However, investment in health information processes necessary to promote the use of this certificate and improve mortality information is lacking in many countries. An appeal for support to make improvements has been launched through the Health Metrics Network's MOVE-IT strategy (Monitoring of Vital Events Information Technology) (WHO 2011). Despite this international spotlight on the need for capture of mortality data and in the use of the ICD-10 to code the data reported on such certificates, there is little cohesion in the way that certifiers of deaths receive instruction in how to complete the death certificate, which is the main source document for mortality statistics. Complete and accurate documentation of the immediate, underlying and contributory causes of death of the decedent on the death certificate is a requirement to produce standardised statistical information and to the ability to produce cause-specific mortality statistics that can be compared between populations and across time. This paper reports on a research project conducted to determine the efficacy and accessibility of the certification module of the WHO's newly-developed web based training tool for coders and certifiers of deaths. Involving a population of medical students from the Fiji School of Medicine and a pre- and post-research design, the study entailed completion of death certificates based on vignettes before and after access to the training tool. The ability of the participants to complete the death certificates and analysis of the completeness and specificity of the ICD-10 coding of the reported causes of death were used to measure the effect of the students' learning from the training tool. The quality of death certificate completion was assessed using a Quality Index

  10. Neighborhood deprivation, vehicle ownership, and potential spatial access to a variety of fruits and vegetables in a large rural area in Texas

    PubMed Central

    2010-01-01

    Objective There has been limited study of all types of food stores, such as traditional (supercenters, supermarkets, and grocery stores), convenience stores, and non-traditional (dollar stores, mass merchandisers, and pharmacies) as potential opportunities for purchase of fresh and processed (canned and frozen) fruits and vegetables, especially in small-town or rural areas. Methods Data from the Brazos Valley Food Environment Project (BVFEP) are combined with 2000 U.S. Census data for 101 Census block groups (CBG) to examine neighborhood access to fruits and vegetables. BVFEP data included identification and geocoding of all food stores (n = 185) in six rural counties in Texas, using ground-truthed methods and on-site assessment of the availability and variety of fresh and processed fruits and vegetables in all food stores. Access from the population-weighted centroid of each CBG was measured using proximity (minimum network distance) and coverage (number of shopping opportunities) for a good selection of fresh and processed fruits and vegetables. Neighborhood inequalities (deprivation and vehicle ownership) and spatial access for fruits and vegetables were examined using Wilcoxon matched-pairs signed-rank test and multivariate regression models. Results The variety of fruits or vegetables was greater at supermarkets compared with grocery stores. Among non-traditional and convenience food stores, the largest variety was found at dollar stores. On average, rural neighborhoods were 9.9 miles to the nearest supermarket, 6.7 miles and 7.4 miles to the nearest food store with a good variety of fresh fruits and vegetables, respectively, and 4.7 miles and 4.5 miles to a good variety of fresh and processed fruits or vegetables. High deprivation or low vehicle ownership neighborhoods had better spatial access to a good variety of fruits and vegetables, both in the distance to the nearest source and in the number of shopping opportunities. Conclusion Supermarkets and grocery

  11. Spatial contrast sensitivity - Effects of age, test-retest, and psychophysical method

    NASA Technical Reports Server (NTRS)

    Higgins, Kent E.; Jaffe, Myles J.; Caruso, Rafael C.; Demonasterio, Francisco M.

    1988-01-01

    Two different psychophysical methods were used to test the spatial contrast sensitivity in normal subjects from five age groups. The method of adjustment showed a decline in sensitivity with increasing age at all spatial frequencies, while the forced-choice procedure showed an age-related decline predominantly at high spatial frequencies. It is suggested that a neural component is responsible for this decline.

  12. Spatial and temporal variability of Antarctic precipitation from atmospheric methods

    SciTech Connect

    Cullather, R.L.; Bromwich, D.H.; Van Woert, M.L.

    1998-03-01

    The spatial and temporal variability of net precipitation (precipitation minus evaporation/sublimation) for Antarctica derived from the European Centre for Medium-Range Weather Forecasts operational analyses via the atmospheric moisture budget is assessed in comparison to a variety of glaciological and meteorological observations and datasets. For the 11-yr period 1985-95, the average continental value is 151 mm yr{sup {minus}1} water equivalent. Large regional differences with other datasets are identified, and the sources of error are considered. Interannual variability in the Southern Ocean storm tracks is found to be an important mechanism for enhanced precipitation minus evaporation (P-E) in both east and west Antarctica. In relation to the present findings, an evaluation of the rawinsonde method for estimating net precipitation in east Antarctica is conducted. Estimates of P-E using synthetic rawinsondes derived from the analyses are found to compare favorably to glaciological estimates. A significant upward trend of 2.4 mm yr{sup {minus}1} is found for the Antarctic continent that is consistent with findings from the National Centers for Environmental Prediction, formerly the National Meteorological Center, and the National Center for Atmospheric Research Reanalysis precipitation dataset. Despite large regional discrepancies, the general agreement on the main features of Antarctic precipitation between studies suggests that a threshold has been reached, where the assessment of the smaller terms including evaporation/sublimation and drift snow loss is required to explain the differences. 76 refs., 24 figs., 1 tab.

  13. A Spatial Division Clustering Method and Low Dimensional Feature Extraction Technique Based Indoor Positioning System

    PubMed Central

    Mo, Yun; Zhang, Zhongzhao; Meng, Weixiao; Ma, Lin; Wang, Yao

    2014-01-01

    Indoor positioning systems based on the fingerprint method are widely used due to the large number of existing devices with a wide range of coverage. However, extensive positioning regions with a massive fingerprint database may cause high computational complexity and error margins, therefore clustering methods are widely applied as a solution. However, traditional clustering methods in positioning systems can only measure the similarity of the Received Signal Strength without being concerned with the continuity of physical coordinates. Besides, outage of access points could result in asymmetric matching problems which severely affect the fine positioning procedure. To solve these issues, in this paper we propose a positioning system based on the Spatial Division Clustering (SDC) method for clustering the fingerprint dataset subject to physical distance constraints. With the Genetic Algorithm and Support Vector Machine techniques, SDC can achieve higher coarse positioning accuracy than traditional clustering algorithms. In terms of fine localization, based on the Kernel Principal Component Analysis method, the proposed positioning system outperforms its counterparts based on other feature extraction methods in low dimensionality. Apart from balancing online matching computational burden, the new positioning system exhibits advantageous performance on radio map clustering, and also shows better robustness and adaptability in the asymmetric matching problem aspect. PMID:24451470

  14. A spatial division clustering method and low dimensional feature extraction technique based indoor positioning system.

    PubMed

    Mo, Yun; Zhang, Zhongzhao; Meng, Weixiao; Ma, Lin; Wang, Yao

    2014-01-01

    Indoor positioning systems based on the fingerprint method are widely used due to the large number of existing devices with a wide range of coverage. However, extensive positioning regions with a massive fingerprint database may cause high computational complexity and error margins, therefore clustering methods are widely applied as a solution. However, traditional clustering methods in positioning systems can only measure the similarity of the Received Signal Strength without being concerned with the continuity of physical coordinates. Besides, outage of access points could result in asymmetric matching problems which severely affect the fine positioning procedure. To solve these issues, in this paper we propose a positioning system based on the Spatial Division Clustering (SDC) method for clustering the fingerprint dataset subject to physical distance constraints. With the Genetic Algorithm and Support Vector Machine techniques, SDC can achieve higher coarse positioning accuracy than traditional clustering algorithms. In terms of fine localization, based on the Kernel Principal Component Analysis method, the proposed positioning system outperforms its counterparts based on other feature extraction methods in low dimensionality. Apart from balancing online matching computational burden, the new positioning system exhibits advantageous performance on radio map clustering, and also shows better robustness and adaptability in the asymmetric matching problem aspect. PMID:24451470

  15. Differential Mobility Spectrometer with Spatial Ion Detector and Methods Related Thereto

    NASA Technical Reports Server (NTRS)

    Duong, Tuan A. (Inventor); Kanik, Isik (Inventor); Duong, Vu A. (Inventor)

    2013-01-01

    Differential mobility spectrometer with spatial ion detector and methods related thereto are disclosed. The use of one or more spatial detector within differential mobility spectrometry can provide for the identification and separation of ions with similar mobility and mass.

  16. Early Warning Signals of Ecological Transitions: Methods for Spatial Patterns

    PubMed Central

    Brock, William A.; Carpenter, Stephen R.; Ellison, Aaron M.; Livina, Valerie N.; Seekell, David A.; Scheffer, Marten; van Nes, Egbert H.; Dakos, Vasilis

    2014-01-01

    A number of ecosystems can exhibit abrupt shifts between alternative stable states. Because of their important ecological and economic consequences, recent research has focused on devising early warning signals for anticipating such abrupt ecological transitions. In particular, theoretical studies show that changes in spatial characteristics of the system could provide early warnings of approaching transitions. However, the empirical validation of these indicators lag behind their theoretical developments. Here, we summarize a range of currently available spatial early warning signals, suggest potential null models to interpret their trends, and apply them to three simulated spatial data sets of systems undergoing an abrupt transition. In addition to providing a step-by-step methodology for applying these signals to spatial data sets, we propose a statistical toolbox that may be used to help detect approaching transitions in a wide range of spatial data. We hope that our methodology together with the computer codes will stimulate the application and testing of spatial early warning signals on real spatial data. PMID:24658137

  17. Louisiana coastal GIS network: Graphical user interface for access to spatial data

    USGS Publications Warehouse

    Hiland, Matteson; McBride, Randolph A.; Davis, Donald; Braud, Dewitt; Streiffer, Henry; Jones, Farrell; Lewis, Anthony; Williams, S.

    1991-01-01

    Louisiana's coastal wetlands support a large percentage of the nation's seafood and fur industries, vast deposits of oil and natural gas, habitat for thousands of species of plants and animals, winter nesting grounds and migratory paths for numerous waterfowl, and many recreational resources enjoyed by residents and tourists. Louisiana's wetlands also have the highest rates of coastal erosion and wetland loss in the nation. While numerous studies across many disciplines have been conducted on both local and regional scales, no complete inventory exists for this information. The Louisiana Coastal Geographic Information System Network (LCGISN) is currently being developed to facilitate access to existing data for coastal zone planners, managers, and researchers. The Louisiana Geological Survey (LGS), in cooperation with the LSU Department of Geography and Anthropology, the Computer Aided Design and Geographic Information Systems Research Laboratory (CADGIS), and others, is pursuing this project under the terms of a cooperative agreement with the U.S. Geological Survey. LCGISN is an automated system for searching and retrieving geographic, cartographic, and bibliographic data. By linking original programming with an existing GIS software package and an industry standard relational database management system, LCGISN will provide the capability for users to search for data references by interactively defining the area of interest on a displayed map/image reference background. Several agencies will be networked to provide easy access to a wide variety of information. LCGISN, with its headquarters at LGS, will serve as the central node on the network, providing data format conversions, projection and datum transformations, and storage of several of the most commonly used data sets. Thematic mapper data, USGS 7.5-minute quadrangle map boundaries, political and legal boundaries, major transportation routes, and other digital data will provide a base map to aid the user in

  18. A dynamic access control method based on QoS requirement

    NASA Astrophysics Data System (ADS)

    Li, Chunquan; Wang, Yanwei; Yang, Baoye; Hu, Chunyang

    2013-03-01

    A dynamic access control method is put forward to ensure the security of the sharing service in Cloud Manufacturing, according to the application characteristics of cloud manufacturing collaborative task. The role-based access control (RBAC) model is extended according to the characteristics of cloud manufacturing in this method. The constraints are considered, which are from QoS requirement of the task context to access control, based on the traditional static authorization. The fuzzy policy rules are established about the weighted interval value of permissions. The access control authorities of executable service by users are dynamically adjusted through the fuzzy reasoning based on the QoS requirement of task. The main elements of the model are described. The fuzzy reasoning algorithm of weighted interval value based QoS requirement is studied. An effective method is provided to resolve the access control of cloud manufacturing.

  19. Method and apparatus for measuring spatial uniformity of radiation

    DOEpatents

    Field, Halden

    2002-01-01

    A method and apparatus for measuring the spatial uniformity of the intensity of a radiation beam from a radiation source based on a single sampling time and/or a single pulse of radiation. The measuring apparatus includes a plurality of radiation detectors positioned on planar mounting plate to form a radiation receiving area that has a shape and size approximating the size and shape of the cross section of the radiation beam. The detectors concurrently receive portions of the radiation beam and transmit electrical signals representative of the intensity of impinging radiation to a signal processor circuit connected to each of the detectors and adapted to concurrently receive the electrical signals from the detectors and process with a central processing unit (CPU) the signals to determine intensities of the radiation impinging at each detector location. The CPU displays the determined intensities and relative intensity values corresponding to each detector location to an operator of the measuring apparatus on an included data display device. Concurrent sampling of each detector is achieved by connecting to each detector a sample and hold circuit that is configured to track the signal and store it upon receipt of a "capture" signal. A switching device then selectively retrieves the signals and transmits the signals to the CPU through a single analog to digital (A/D) converter. The "capture" signal. is then removed from the sample-and-hold circuits. Alternatively, concurrent sampling is achieved by providing an A/D converter for each detector, each of which transmits a corresponding digital signal to the CPU. The sampling or reading of the detector signals can be controlled by the CPU or level-detection and timing circuit.

  20. The Earth System Grid Federation: An Open Infrastructure for Access to Distributed Geo-Spatial Data

    SciTech Connect

    Cinquini, Luca; Crichton, Daniel; Miller, Neill; Mattmann, Chris; Harney, John F; Shipman, Galen M; Wang, Feiyi; Bell, Gavin; Drach, Bob; Ananthakrishnan, Rachana; Pascoe, Stephen; Fiore, Sandro; Schweitzer, Roland; Danvil, Sebastian; Morgan, Mark

    2012-01-01

    The Earth System Grid Federation (ESGF) is a multi-agency, international collaboration that aims at developing the software infrastructure needed to facilitate and empower the study of climate change on a global scale. The ESGF s architecture employs a system of geographically distributed peer nodes, which are independently administered yet united by the adoption of common federation protocols and application programming interfaces (APIs). The cornerstones of its interoperability are the peer-to-peer messaging that is continuously exchanged among all nodes in the federation; a shared architecture and API for search and discovery; and a security infrastructure based on industry standards (OpenID, SSL, GSI and SAML). The ESGF software is developed collaboratively across institutional boundaries and made available to the community as open source. It has now been adopted by multiple Earth science projects and allows access to petabytes of geophysical data, including the entire model output used for the next international assessment report on climate change (IPCC-AR5) and a suite of satellite observations (obs4MIPs) and reanalysis data sets (ANA4MIPs).

  1. MExLab Planetary Geoportal: 3D-access to planetary images and results of spatial data analysis

    NASA Astrophysics Data System (ADS)

    Karachevtseva, I.; Garov, A.

    2015-10-01

    MExLab Planetary Geoportal was developed as Geodesy and Cartography Node which provide access to results of study of celestial bodies such as DEM and orthoimages, as well as basemaps, crater catalogues and derivative products: slope, roughness, crater density (http://cartsrv.mexlab.ru/geoportal). The main feature of designed Geoportal is the ability of spatial queries and access to the contents selecting from the list of available data set (Phobos, Mercury, Moon, including Lunokhod's archive data). Prior version of Geoportal has been developed using Flash technology. Now we are developing new version which will use 3D-API (OpenGL, WebGL) based on shaders not only for standard 3D-functionality, but for 2D-mapping as well. Users can obtain quantitative and qualitative characteristics of the objects in graphical, tabular and 3D-forms. It will bring the advantages of unification of code and speed of processing and provide a number of functional advantages based on GIS-tools such as: - possibility of dynamic raster transform for needed map projection; - effective implementation of the co-registration of planetary images by combining spatial data geometries; - presentation in 3D-form different types of data, including planetary atmospheric measurements, subsurface radar data, ect. The system will be created with a new software architecture, which has a potential for development and flexibility in reconfiguration based on cross platform solution: - an application for the three types of platforms: desktop (Windows, Linux, OSX), web platform (any HTML5 browser), and mobile application (Android, iOS); - a single codebase shared between platforms (using cross compilation for Web); - a new telecommunication solution to connect between modules and external system like PROVIDE WebGIS (http://www.provide-space.eu/progis/). The research leading to these result was partly supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n

  2. Final Report: Advanced Methods for Accessing and Disseminating Nuclear Data, August 13, 1996 - March 15, 1999

    SciTech Connect

    Stone, Craig A.

    1999-03-15

    Scientific Digital Visions, Inc. developed methods of accessing and dissemination nuclear data contained within the databases of the National Data Center (NNDC) at the Brookhaven National Laboratory supporting a long standing and important DOE Program to provide scientists access to NNDC Databases. The NNDC participated as a partner in this effort.

  3. Action Research to Improve Methods of Delivery and Feedback in an Access Grid Room Environment

    ERIC Educational Resources Information Center

    McArthur, Lynne C.; Klass, Lara; Eberhard, Andrew; Stacey, Andrew

    2011-01-01

    This article describes a qualitative study which was undertaken to improve the delivery methods and feedback opportunity in honours mathematics lectures which are delivered through Access Grid Rooms. Access Grid Rooms are facilities that provide two-way video and audio interactivity across multiple sites, with the inclusion of smart boards. The…

  4. [Comparison of spatial interpolation methods for daily meteorological elements].

    PubMed

    Jiang, Xiao-Jian; Liu, Xiao-Jun; Huang, Fen; Jiang, Hai-Yan; Cao, Wei-Xing; Zhu, Yan

    2010-03-01

    A comparative study was made to evaluate the methods of inverse distance weighting (IDW), co-kriging (CK), and thin plate spline (TPS) in interpolating the average meteorological elements (including maximum air temperature, minimum air temperature, sunshine hours, and precipitation) of the 15th day per month from the 1951-2005 comprehensive observation data of 559 meteorological stations in China. The results showed that the RMSEs for the maximum and minimum air temperature in a year interpolated by TPS were the smallest (1.02 degrees C and 1.12 degrees C, respectively), and the R2 between the observed and predicted values were the highest (0.9916 and 0.9913, respectively), compared with those interpolated by IDW and CK. In four seasons, the smallest RMSEs for the maximum and minimum air temperature interpolated by TPS were observed in autumn (0.83 degrees C) and summer (0.86 degrees C), respectively, and the R2 between the observed and predicted values interpolated by TPS were higher in autumn than in other seasons. The RMSEs for the sunshine hours and precipitation in a year interpolated by TPS were the smallest (0.59 h and 1.01 mm, respectively), and the R2 between the observed and predicted values were the highest (0.9118 and 0.8135, respectively), compared with those interpolated by IDW and CK. In four seasons, the RMSE for the sunshine hours in winter interpolated by TPS was the smallest (0.49 h), and the R2 between the observed and predicted sunshine hours was the smallest (0.9293). The RMSE for the precipitation in winter interpolated by TPS was the smallest (0.33 mm), while the RMSE for the precipitation in summer interpolated by IDW was the smallest (2.01 mm). The R2 between the observed and predicted precipitation in winter interpolated by CK was the highest (0.8781). It was suggested that TPS could be the optimal spatial interpolation method in interpolating and rasterizing the daily meteorological elements in China. PMID:20560317

  5. Spatial cross modulation method using a random diffuser and phase-only spatial light modulator for constructing arbitrary complex fields.

    PubMed

    Shibukawa, Atsushi; Okamoto, Atsushi; Takabayashi, Masanori; Tomita, Akihisa

    2014-02-24

    We propose a spatial cross modulation method using a random diffuser and a phase-only spatial light modulator (SLM), by which arbitrary complex-amplitude fields can be generated with higher spatial resolution and diffraction efficiency than off-axis and double-phase computer-generated holograms. Our method encodes the original complex object as a phase-only diffusion image by scattering the complex object using a random diffuser. In addition, all incoming light to the SLM is consumed for a single diffraction order, making a diffraction efficiency of more than 90% possible. This method can be applied for holographic data storage, three-dimensional displays, and other such applications. PMID:24663718

  6. Spatial analysis of agro-ecological data: Detection of spatial patterns combining three different methodical approaches

    NASA Astrophysics Data System (ADS)

    Heuer, A.; Casper, M. C.; Vohland, M.

    2009-04-01

    Processes in natural systems and the resulting patterns occur in ecological space and time. To study natural structures and to understand the functional processes it is necessary to identify the relevant spatial and temporal space at which these all occur; or with other words to isolate spatial and temporal patterns. In this contribution we will concentrate on the spatial aspects of agro-ecological data analysis. Data were derived from two agricultural plots, each of about 5 hectares, in the area of Newel, located in Western Palatinate, Germany. The plots had been conventionally cultivated with a crop rotation of winter rape, winter wheat and spring barley. Data about physical and chemical soil properties, vegetation and topography were i) collected by measurements in the field during three vegetation periods (2005-2008) and/or ii) derived from hyperspectral image data, acquired by a HyMap airborne imaging sensor (2005). To detect spatial variability within the plots, we applied three different approaches that examine and describe relationships among data. First, we used variography to get an overview of the data. A comparison of the experimental variograms facilitated to distinguish variables, which seemed to occur in related or dissimilar spatial space. Second, based on data available in raster-format basic cell statistics were conducted, using a geographic information system. Here we could make advantage of the powerful classification and visualization tool, which supported the spatial distribution of patterns. Third, we used an approach that is being used for visualization of complex highly dimensional environmental data, the Kohonen self-organizing map. The self-organizing map (SOM) uses multidimensional data that gets further reduced in dimensionality (2-D) to detect similarities in data sets and correlation between single variables. One of SOM's advantages is its powerful visualization capability. The combination of the three approaches leads to

  7. Organizational Communication Assessment: Fuzzy Methods and the Accessibility of Symbols.

    ERIC Educational Resources Information Center

    Meyer, John C.

    2002-01-01

    Describes two interpretive methodological directions available to organizational assessors: textual analysis, or hermeneutics; and ethnomethodology. Explains that to apply these methods, assessment of organizational symbols in messages requires emphasis on three types of data: researcher observations; member responses; and transcripts of…

  8. Evaluation Method for Accessibility to Hollow Space of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Fan, Jing; Yudasaka, Masako; Miyawaki, Jin; Iijima, Sumio

    2004-03-01

    For application of single-wall carbon nanotubes (SWNTs) and nanohorns (SWNHs) to material-storage media, holes are opened usually by oxidation through which materials enter inside the hollow space of tubes. The holes are known to pass only molecules with diameters smaller than those of the holes, thus molecular-size selective storage of gases inside tubes becomes possible [1]. To enhance utilities of inner hollow space of carbon nanoutbes, controlled opening of holes is important. It is especially so for SWNHs, because holes with various diameters are potentially available due to the various types of defects on the tube walls. We studied the methods of hole-opening for SWNHs, and, at the same time, developed simple methods for evaluating the sizes of holes and the volumes of inner hollow-spaces. [1] Murata et al. J. Phys.Chem.

  9. Accessing inoculation methods of maize and wheat with Azospirillum brasilense.

    PubMed

    Fukami, Josiane; Nogueira, Marco Antonio; Araujo, Ricardo Silva; Hungria, Mariangela

    2016-03-01

    The utilization of inoculants containing Azospirillum is becoming more popular due to increasing reports of expressive gains in grain yields. However, incompatibility with pesticides used in seed treatments represents a main limitation for a successful inoculation. Therefore, in this study we searched for alternatives methods for seed inoculation of maize and wheat, aiming to avoid the direct contact of bacteria with pesticides. Different doses of inoculants containing Azospirillum brasilense were employed to perform inoculation in-furrow, via soil spray at sowing and via leaf spray after seedlings had emerged, in comparison to seed inoculation. Experiments were conducted first under greenhouse controlled conditions and then confirmed in the field at different locations in Brazil. In the greenhouse, most parameters measured responded positively to the largest inoculant dose used in foliar sprays, but benefits could also be observed from both in-furrow and soil spray inoculation. However, our results present evidence that field inoculation with plant-growth promoting bacteria must consider inoculant doses, and point to the need of fine adjustments to avoid crossing the threshold of growth stimulation and inhibition. All inoculation techniques increased the abundance of diazotrophic bacteria in plant tissues, and foliar spray improved colonization of leaves, while soil inoculations favored root and rhizosphere colonization. In field experiments, inoculation with A. brasilense allowed for a 25 % reduction in the need for N fertilizers. Our results have identified alternative methods of inoculation that were as effective as the standard seed inoculation that may represent an important strategy to avoid the incompatibility between inoculant bacteria and pesticides employed for seed treatment. PMID:26759120

  10. The effect of alkaline pretreatment methods on cellulose structure and accessibility.

    PubMed

    Bali, Garima; Meng, Xianzhi; Deneff, Jacob I; Sun, Qining; Ragauskas, Arthur J

    2015-01-01

    The effects of different alkaline pretreatments on cellulose structural features and accessibility are compared and correlated with the enzymatic hydrolysis of Populus. The pretreatments are shown to modify polysaccharides and lignin content to enhance the accessibility for cellulase enzymes. The highest increase in the cellulose accessibility was observed in dilute sodium hydroxide, followed by methods using ammonia soaking and lime (Ca(OH)2 ). The biggest increase of cellulose accessibility occurs during the first 10 min of pretreatment, with further increases at a slower rate as severity increases. Low temperature ammonia soaking at longer residence times dissolved a major portion of hemicellulose and exhibited higher cellulose accessibility than high temperature soaking. Moreover, the most significant reduction of degree of polymerization (DP) occurred for dilute sodium hydroxide (NaOH) and ammonia pretreated Populus samples. The study thus identifies important cellulose structural features and relevant parameters related to biomass recalcitrance. PMID:25421020

  11. Spatial and temporal variations in ammonia emissions - a freely accessible model code for Europe

    NASA Astrophysics Data System (ADS)

    Skjøth, C. A.; Geels, C.; Berge, H.; Gyldenkærne, S.; Fagerli, H.; Ellermann, T.; Frohn, L. M.; Christensen, J.; Hansen, K. M.; Hansen, K.; Hertel, O.

    2011-01-01

    Deriving a parameterisation of ammonia emissions for use in chemistry-transport models (CTMs) is a complex problem as the emission varies locally as a result of local climate and local agricultural management. In current CTMs such factors are generally not taken into account. This paper demonstrates how local climate and local management can be accounted for in CTMs by applying a modular approach for deriving data as input to a dynamic ammonia emission model for Europe. Default data are obtained from information in the RAINS system, and it is demonstrated how this dynamic emission model based on these input data improves the NH3 calculations in a CTM model when the results are compared with calculations obtained by traditional methods in emission handling. It is also shown how input data can be modified over a specific target region resulting in even further improvement in performance over this domain. The model code and the obtained default values for the modelling experiments are available as a Supplement to this article for use by the modelling community on similar terms as the EMEP CTM model: the GPL license v3.

  12. Spatial and temporal variations in ammonia emissions - a freely accessible model code for Europe

    NASA Astrophysics Data System (ADS)

    Skjøth, C. A.; Geels, C.; Berge, H.; Gyldenkærne, S.; Fagerli, H.; Ellermann, T.; Frohn, L. M.; Christensen, J.; Hansen, K. M.; Hansen, K.; Hertel, O.

    2011-06-01

    Deriving a parameterisation of ammonia emissions for use in chemistry-transport models (CTMs) is a complex problem as the emission varies locally as a result of local climate and local agricultural management. In current CTMs such factors are generally not taken into account. This paper demonstrates how local climate and local management can be accounted for in CTMs by applying a modular approach for deriving data as input to a dynamic ammonia emission model for Europe. Default data are obtained from information in the RAINS system, and it is demonstrated how this dynamic emission model based on these input data improves the NH3 calculations in a CTM model when the results are compared with calculations obtained by traditional methods in emission handling. It is also shown how input data can be modified over a specific target region resulting in even further improvement in performance over this domain. The model code and the obtained default values for the modelling experiments are available as supplementary information to this article for use by the modelling community on similar terms as the EMEP CTM model: the GPL licencse v3.

  13. Design and implementation of visualization methods for the CHANGES Spatial Decision Support System

    NASA Astrophysics Data System (ADS)

    Cristal, Irina; van Westen, Cees; Bakker, Wim; Greiving, Stefan

    2014-05-01

    The CHANGES Spatial Decision Support System (SDSS) is a web-based system aimed for risk assessment and the evaluation of optimal risk reduction alternatives at local level as a decision support tool in long-term natural risk management. The SDSS use multidimensional information, integrating thematic, spatial, temporal and documentary data. The role of visualization in this context becomes of vital importance for efficiently representing each dimension. This multidimensional aspect of the required for the system risk information, combined with the diversity of the end-users imposes the use of sophisticated visualization methods and tools. The key goal of the present work is to exploit efficiently the large amount of data in relation to the needs of the end-user, utilizing proper visualization techniques. Three main tasks have been accomplished for this purpose: categorization of the end-users, the definition of system's modules and the data definition. The graphical representation of the data and the visualization tools were designed to be relevant to the data type and the purpose of the analysis. Depending on the end-users category, each user should have access to different modules of the system and thus, to the proper visualization environment. The technologies used for the development of the visualization component combine the latest and most innovative open source JavaScript frameworks, such as OpenLayers 2.13.1, ExtJS 4 and GeoExt 2. Moreover, the model-view-controller (MVC) pattern is used in order to ensure flexibility of the system at the implementation level. Using the above technologies, the visualization techniques implemented so far offer interactive map navigation, querying and comparison tools. The map comparison tools are of great importance within the SDSS and include the following: swiping tool for comparison of different data of the same location; raster subtraction for comparison of the same phenomena varying in time; linked views for comparison

  14. Gendered Distances: A Methodological Inquiry into Spatial Analysis as an Instrument for Assessing Gender Equality in Access to Secondary Schools in Mukono District, Uganda

    ERIC Educational Resources Information Center

    Wawro, Patrick R.

    2010-01-01

    This study focused on how accessibility to secondary schools in the Mukono District of Uganda is related to the sex and gender of the student and the distance that separates the student's home from the school they attend. This research is a methodological inquiry exploring the use of spatial analysis, specifically how cognitive and metric…

  15. A new two dimensional spectral/spatial multi-diagonal code for noncoherent optical code division multiple access (OCDMA) systems

    NASA Astrophysics Data System (ADS)

    Kadhim, Rasim Azeez; Fadhil, Hilal Adnan; Aljunid, S. A.; Razalli, Mohamad Shahrazel

    2014-10-01

    A new two dimensional codes family, namely two dimensional multi-diagonal (2D-MD) codes, is proposed for spectral/spatial non-coherent OCDMA systems based on the one dimensional MD code. Since the MD code has the property of zero cross correlation, the proposed 2D-MD code also has this property. So that, the multi-access interference (MAI) is fully eliminated and the phase induced intensity noise (PIIN) is suppressed with the proposed code. Code performance is analyzed in terms of bit error rate (BER) while considering the effect of shot noise, PIIN, and thermal noise. The performance of the proposed code is compared with the related MD, modified quadratic congruence (MQC), two dimensional perfect difference (2D-PD) and two dimensional diluted perfect difference (2D-DPD) codes. The analytical and the simulation results reveal that the proposed 2D-MD code outperforms the other codes. Moreover, a large number of simultaneous users can be accommodated at low BER and high data rate.

  16. AREA RESTRICTIONS, RISK, HARM, AND HEALTH CARE ACCESS AMONG PEOPLE WHO USE DRUGS IN VANCOUVER, CANADA: A SPATIALLY ORIENTED QUALITATIVE STUDY

    PubMed Central

    McNeil, Ryan; Cooper, Hannah; Small, Will; Kerr, Thomas

    2015-01-01

    Area restrictions prohibiting people from entering drug scenes or areas where they were arrested are a common socio-legal mechanism employed to regulate the spatial practices of people who use drugs (PWUD). To explore how socio-spatial patterns stemming from area restrictions shape risk, harm, and health care access, qualitative interviews and mapping exercises were conducted with 24 PWUD with area restrictions in Vancouver, Canada. Area restrictions disrupted access to health and social resources (e.g., HIV care) concentrated in drug scenes, while territorial stigma prevented PWUD from accessing supports in other neighbourhoods. Rather than preventing involvement in drug-related activities, area restrictions displaced these activities to other locations and increased vulnerability to diverse risks and harms (e.g., unsafe drug use practices, violence). Given the harms stemming from area restrictions there is an urgent need to reconsider this socio-legal strategy. PMID:26241893

  17. Spatial content-based scene matching using a relaxation method

    NASA Astrophysics Data System (ADS)

    Wang, Caixia

    Scene matching is a fundamental task for a variety of geospatial analysis applications. As we move towards multi-source data analysis, constantly increasing amounts of generated geospatial datasets and the diversification of data sources are the two major forces driving the need for novel and more efficient matching solutions. Despite the great effort within the geospatial and computer science communities, automated scene matching still remains crucial and challenging when vector data are involved such as image-to-map registration for change detection. In this context, features extracted from vector data contain no intensity information which typically is the significant component in current promising approaches for registration. This problem becomes increasingly complicated as the two or more datasets usually present differences in coverage, scale, or orientation in general, and accordingly corresponding objects in the two or more datasets may also differ to a certain extent. This dissertation developed a novel methodology for automatic image-to-vector matching, based on contextual information among salient spatial features (e.g. road networks and buildings) in a scene. In this work, we model the road networks extracted from the two to-be-matched datasets as attributed graphs . The developed attribute metric measures the geometric and topological properties of the road network, which are invariant to the differences of the two datasets in scale, orientation, area of coverage, physical changes and extraction errors. Road networks comprise line segments (or curves), intersections and loops. Such complex structure suggests versatile attributes derivable from the components themselves of the road networks as well as between these components. It is important to develop attributes that need less computational efforts, while having sufficient descriptive power. We extend the entropy concept to statistically measure the descriptive quality of the attributes under

  18. Method and apparatus for spatially uniform electropolishing and electrolytic etching

    DOEpatents

    Mayer, Steven T.; Contolini, Robert J.; Bernhardt, Anthony F.

    1992-01-01

    In an electropolishing or electrolytic etching apparatus the anode is separated from the cathode to prevent bubble transport to the anode and to produce a uniform current distribution at the anode by means of a solid nonconducting anode-cathode barrier. The anode extends into the top of the barrier and the cathode is outside the barrier. A virtual cathode hole formed in the bottom of the barrier below the level of the cathode permits current flow while preventing bubble transport. The anode is rotatable and oriented horizontally facing down. An extended anode is formed by mounting the workpiece in a holder which extends the electropolishing or etching area beyond the edge of the workpiece to reduce edge effects at the workpiece. A reference electrode controls cell voltage. Endpoint detection and current shut-off stop polishing. Spatially uniform polishing or etching can be rapidly performed.

  19. Method and apparatus for spatially uniform electropolishing and electrolytic etching

    DOEpatents

    Mayer, S.T.; Contolini, R.J.; Bernhardt, A.F.

    1992-03-17

    In an electropolishing or electrolytic etching apparatus the anode is separated from the cathode to prevent bubble transport to the anode and to produce a uniform current distribution at the anode by means of a solid nonconducting anode-cathode barrier. The anode extends into the top of the barrier and the cathode is outside the barrier. A virtual cathode hole formed in the bottom of the barrier below the level of the cathode permits current flow while preventing bubble transport. The anode is rotatable and oriented horizontally facing down. An extended anode is formed by mounting the workpiece in a holder which extends the electropolishing or etching area beyond the edge of the workpiece to reduce edge effects at the workpiece. A reference electrode controls cell voltage. Endpoint detection and current shut-off stop polishing. Spatially uniform polishing or etching can be rapidly performed. 6 figs.

  20. A hybrid method with deviational particles for spatial inhomogeneous plasma

    NASA Astrophysics Data System (ADS)

    Yan, Bokai

    2016-03-01

    In this work we propose a Hybrid method with Deviational Particles (HDP) for a plasma modeled by the inhomogeneous Vlasov-Poisson-Landau system. We split the distribution into a Maxwellian part evolved by a grid based fluid solver and a deviation part simulated by numerical particles. These particles, named deviational particles, could be both positive and negative. We combine the Monte Carlo method proposed in [31], a Particle in Cell method and a Macro-Micro decomposition method [3] to design an efficient hybrid method. Furthermore, coarse particles are employed to accelerate the simulation. A particle resampling technique on both deviational particles and coarse particles is also investigated and improved. This method is applicable in all regimes and significantly more efficient compared to a PIC-DSMC method near the fluid regime.

  1. Infrared image segmentation method based on spatial coherence histogram and maximum entropy

    NASA Astrophysics Data System (ADS)

    Liu, Songtao; Shen, Tongsheng; Dai, Yao

    2014-11-01

    In order to segment the target well and suppress background noises effectively, an infrared image segmentation method based on spatial coherence histogram and maximum entropy is proposed. First, spatial coherence histogram is presented by weighting the importance of the different position of these pixels with the same gray-level, which is obtained by computing their local density. Then, after enhancing the image by spatial coherence histogram, 1D maximum entropy method is used to segment the image. The novel method can not only get better segmentation results, but also have a faster computation time than traditional 2D histogram-based segmentation methods.

  2. An integrated spatial snap-shot monitoring method for identifying seasonal changes and spatial changes in surface water quality

    NASA Astrophysics Data System (ADS)

    Chittoor Viswanathan, Vidhya; Jiang, Yongjun; Berg, Michael; Hunkeler, Daniel; Schirmer, Mario

    2016-08-01

    Integrated catchment-scale management approaches in large catchments are often hindered due to the poor understanding of the spatially and seasonally variable pathways of pollutants. High-frequency monitoring of water quality at random locations in a catchment is resource intensive and challenging. A simplified catchment-scale monitoring approach is developed in this study, for the preliminary identification of water quality changes - Integrated spatial snap-shot monitoring (ISSM). This multi-parameter monitoring approach is applied using the isotopes of water (δ18O-H2O and δD) and nitrate (δ15N-NO3- and δ18O-NO3-) together with the fluxes of nitrate and other solutes, which are used as chemical markers. This method involves selection of few sampling stations, which are identified as the hotspots of water quality changes within the catchment. The study was conducted in the peri-alpine Thur catchment in Switzerland, with two snap-shot campaigns (representative of two widely varying hydrological conditions), in summer 2012 (low flow) and spring 2013 (high flow). Significant spatial (varying with elevation) and seasonal changes in the sources of water were observed between the two seasons. A spatial variation of the sources of nitrate and the solute loads was observed, in tandem with the land use changes in the Thur catchment. There is a seasonal shift in the sources of nitrate, it varies from a strong treated waste water signature during the low flow season to a mixture of other sources (like soil nitrogen derived from agriculture), in the high flow season. This demonstrates the influence of other sources that override the influence of waste water treatment plants (WWTPs) during high flow in the Thur River and its tributaries. This method is expected to be a cost-effective alternative, providing snap-shots, that can help in the preliminary identification of the pathways of solutes and their seasonal/spatial changes in catchments.

  3. 47 CFR 51.321 - Methods of obtaining interconnection and access to unbundled elements under section 251 of the Act.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... or access to unbundled network elements at a particular point upon a request by a telecommunications carrier. (b) Technically feasible methods of obtaining interconnection or access to unbundled network... method of obtaining interconnection or access to unbundled network elements at a particular premises...

  4. 47 CFR 51.321 - Methods of obtaining interconnection and access to unbundled elements under section 251 of the Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... or access to unbundled network elements at a particular point upon a request by a telecommunications carrier. (b) Technically feasible methods of obtaining interconnection or access to unbundled network... method of obtaining interconnection or access to unbundled network elements at a particular premises...

  5. Multi-views storage model and access methods of conversation history in converged IP messaging system

    NASA Astrophysics Data System (ADS)

    Lu, Meilian; Yang, Dong; Zhou, Xing

    2013-03-01

    Based on the analysis of the requirements of conversation history storage in CPM (Converged IP Messaging) system, a Multi-views storage model and access methods of conversation history are proposed. The storage model separates logical views from physical storage and divides the storage into system managed region and user managed region. It simultaneously supports conversation view, system pre-defined view and user-defined view of storage. The rationality and feasibility of multi-view presentation, the physical storage model and access methods are validated through the implemented prototype. It proves that, this proposal has good scalability, which will help to optimize the physical data storage structure and improve storage performance.

  6. Modeling the spatial shape of nondiffracting beams: Experimental generation of Frozen Waves via holographic method

    NASA Astrophysics Data System (ADS)

    Vieira, Tárcio A.; Zamboni-Rached, Michel; Gesualdi, Marcos R. R.

    2014-03-01

    In this paper we experimentally implement the spatial shape modeling of nondiffracting optical beams via computer generated holograms reconstructed optically by spatial light modulators. The results reported here are an experimental confirmation of the so-called Frozen Wave method, developed a few years ago. Optical beams of this type have potential applications in optical tweezers, medicine, atom guiding, remote sensing, etc.

  7. Are spectral or spatial methods better for pansharpening? An evaluation for four sample methods based on spatial modulation of pixel spectra

    NASA Astrophysics Data System (ADS)

    Alparone, Luciano; Garzelli, Andrea; Vivone, Gemine

    2015-10-01

    The majority of pansharpening methods can be classified as spectral or spatial methods, depending on whether they are based on component substitution (CS) or multiresolution analysis (MRA). So far, the suitability of one class or methods rather than another has been seldom discussed. In this paper, through experiments on IKONOS and simulated Pléiades datasets, the authors demonstrate that the performances of spectral methods depend on the extent of spectral matching, measured by the coefficient of determination (CD) of the multivariate regression between MS and P. For data with simulated P, CD is very close to one and all methods perform almost identically. For true IKONOS datasets, the CD is few percent lower and spatial methods, once they have been optimized through the knowledge of the modulation transfer function (MTF) of the imaging system, are always more performing than spectral methods. Since spatial methods are unaffected by the spectral matching, they are preferable whenever such an issue is critical, e.g., for hyperspectral pansharpening.

  8. A stabilized, symmetric Nitsche method for spatially localized plasticity

    NASA Astrophysics Data System (ADS)

    Truster, Timothy J.

    2016-01-01

    A heterogeneous interface method is developed for combining primal displacement and mixed displacement-pressure formulations across nonconforming finite element meshes to treat volume-preserving plastic flow. When the zone of inelastic response is localized within a larger domain, significant computational savings can be achieved by confining the mixed formulation solely to the localized region. The method's distinguishing feature is that the coupling terms for joining dissimilar element types are derived from a time-discrete free energy functional, which is based on a Lagrange multiplier formulation of the interface constraints. Incorporating residual-based stabilizing terms at the interface enables the condensation of the multiplier field, leading to a symmetric Nitsche formulation in which the interface operators respect the differing character of the governing equations in each region. In a series of numerical problems, the heterogeneous interface method achieved comparable results on coarser meshes as those obtained from applying the mixed formulation throughout the domain.

  9. Monitoring Method of Cow Anthrax Based on Gis and Spatial Statistical Analysis

    NASA Astrophysics Data System (ADS)

    Li, Lin; Yang, Yong; Wang, Hongbin; Dong, Jing; Zhao, Yujun; He, Jianbin; Fan, Honggang

    Geographic information system (GIS) is a computer application system, which possesses the ability of manipulating spatial information and has been used in many fields related with the spatial information management. Many methods and models have been established for analyzing animal diseases distribution models and temporal-spatial transmission models. Great benefits have been gained from the application of GIS in animal disease epidemiology. GIS is now a very important tool in animal disease epidemiological research. Spatial analysis function of GIS can be widened and strengthened by using spatial statistical analysis, allowing for the deeper exploration, analysis, manipulation and interpretation of spatial pattern and spatial correlation of the animal disease. In this paper, we analyzed the cow anthrax spatial distribution characteristics in the target district A (due to the secret of epidemic data we call it district A) based on the established GIS of the cow anthrax in this district in combination of spatial statistical analysis and GIS. The Cow anthrax is biogeochemical disease, and its geographical distribution is related closely to the environmental factors of habitats and has some spatial characteristics, and therefore the correct analysis of the spatial distribution of anthrax cow for monitoring and the prevention and control of anthrax has a very important role. However, the application of classic statistical methods in some areas is very difficult because of the pastoral nomadic context. The high mobility of livestock and the lack of enough suitable sampling for the some of the difficulties in monitoring currently make it nearly impossible to apply rigorous random sampling methods. It is thus necessary to develop an alternative sampling method, which could overcome the lack of sampling and meet the requirements for randomness. The GIS computer application software ArcGIS9.1 was used to overcome the lack of data of sampling sites.Using ArcGIS 9.1 and GEODA

  10. Development of a spatial method for weed detection and localization

    NASA Astrophysics Data System (ADS)

    Vioix, Jean-Baptiste; Douzals, Jean-Paul; Truchetet, Fréd. éric

    2004-02-01

    This paper presents an algorithm specifically developed for filtering low frequency signals. The application is related to weed detection into aerial images where crop lines are detected as repetitive structures. Theoretical bases of this work are presented first. Then, two methods are compared to select low frequency signals and their limitations are described. A decomposition based on wavelet packet is used to combine advantages of both methods. This algorithm allows a high selectivity of low frequency signals with an interesting computation time. At last, a complete algorithm for weed/crop classification is explained and a few results are shown.

  11. Extra-corporeal blood access, sensing, and radiation methods and apparatuses

    NASA Technical Reports Server (NTRS)

    Castle, Kent D. (Inventor)

    1993-01-01

    The described invention is related to extra-corporeal blood access and radiation methods and apparatuses and, in particular, to subjecting flowing blood to energy in variety of forms, including radiation, electromagnetic force fields or atomic particles. It is directed to methods and apparatuses for accessing flowing blood and for subjecting the blood to electrical conductive, electrostatic or electromagnetic fields or for radiating the blood with some type of radiation, e.g., radio waves, ultrasonic or audio waves, microwaves, IR rays, visible light, UV radiation, x-rays, alpha, beta or gamma rays. An apparatus is employed which includes one or more access ports or windows for radiating blood and/or for sensing/analyzing blood. This invention is useful for killing viruses and bacteria in blood, monitoring blood for medical purposes, genetic modification of blood, and analyzing and/or treating blood components.

  12. Mapping Norway - A Method to Register and Survey the Status of Accessibility.

    PubMed

    Bögelsack, Kathrin; Michaelis, Sven

    2016-01-01

    The Norwegian mapping authority has developed an APP and a standard method for mapping accessibility for people with limited or no walking abilities, the blind and the partially sighted in urban and recreational areas. We choose an object-orientated approach where points, lines and polygons represents objects in the environment. All data are stored in a geospatial database, so they can be presented as web map and analysed using GIS software. To this day, more than 160 municipalities are mapped using that method. The aim of this project is to establish a national standard for mapping and to provide a geodatabase that shows the status of accessibility throughout Norway. The data provide a useful tool for national statistics, local planning authorities and private users. First results show that accessibility is low and Norway still faces many challenges to meet the government's goals for Universal Design. PMID:27534365

  13. Aspects of Spatial Influence on Science Teaching Methods.

    ERIC Educational Resources Information Center

    Engelhardt, David Frederic

    A number of aspects of the relationships between characteristics of architectural space and science teaching methods in secondary schools were investigated using teacher questionnaire response and interviews for comparative facilities. Significant factors include--(1) the provision of classroom-laboratories, (2) proximity of the library, (3) size…

  14. a Data Field Method for Urban Remotely Sensed Imagery Classification Considering Spatial Correlation

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Qin, K.; Zeng, C.; Zhang, E. B.; Yue, M. X.; Tong, X.

    2016-06-01

    Spatial correlation between pixels is important information for remotely sensed imagery classification. Data field method and spatial autocorrelation statistics have been utilized to describe and model spatial information of local pixels. The original data field method can represent the spatial interactions of neighbourhood pixels effectively. However, its focus on measuring the grey level change between the central pixel and the neighbourhood pixels results in exaggerating the contribution of the central pixel to the whole local window. Besides, Geary's C has also been proven to well characterise and qualify the spatial correlation between each pixel and its neighbourhood pixels. But the extracted object is badly delineated with the distracting salt-and-pepper effect of isolated misclassified pixels. To correct this defect, we introduce the data field method for filtering and noise limitation. Moreover, the original data field method is enhanced by considering each pixel in the window as the central pixel to compute statistical characteristics between it and its neighbourhood pixels. The last step employs a support vector machine (SVM) for the classification of multi-features (e.g. the spectral feature and spatial correlation feature). In order to validate the effectiveness of the developed method, experiments are conducted on different remotely sensed images containing multiple complex object classes inside. The results show that the developed method outperforms the traditional method in terms of classification accuracies.

  15. Teens' Survey of Stores in the District of Columbia on Accessibility of Family Planning Methods.

    ERIC Educational Resources Information Center

    Center for Population Options, Washington, DC.

    Access to and availability of contraceptive methods in stores play an important role in the prevention of AIDS, unwanted pregnancies, and other sexually transmitted diseases. Although teens are generally knowledgable about birth control, many encounter barriers when attempting to obtain contraceptive. Forty-five drug stores and 15 convenience…

  16. The Method behind the Madness: Acquiring Online Journals and a Solution to Provide Access

    ERIC Educational Resources Information Center

    Skekel, Donna

    2005-01-01

    Libraries are seeking the best possible solution for integrating online journals into their collections. While exploring the different methods and technology available, many libraries still strive to fulfill the original "library mission" proposed by Charles Cutter in his "Rules for a Dictionary Catalog". Providing comprehensive access to…

  17. A Method for Selection of Appropriate Assistive Technology for Computer Access

    ERIC Educational Resources Information Center

    Jenko, Mojca

    2010-01-01

    Assistive technologies (ATs) for computer access enable people with disabilities to be included in the information society. Current methods for assessment and selection of the most appropriate AT for each individual are nonstandardized, lengthy, subjective, and require substantial clinical experience of a multidisciplinary team. This manuscript…

  18. Spatial distortion elimination in integral Fourier holography with intermediate projection views generation method

    NASA Astrophysics Data System (ADS)

    Yang, Chen; Xiao, Xiao; Wang, Xiaorui; Javidi, Bahram

    2014-06-01

    In integral holography, the reconstructed 3D image quality is affected by lenses positional errors in micro-lens array. We analyzed the spatial distortion effects in reconstructed 3D integral Fourier holographic image which are caused by misarrangements of elemental lenses in micro-lens array. Then, an intermediate projection views generation method is used to eliminate the spatial distortion effects in reconstruction. This method provides a solution to adjust the lens-array manufactured errors in realistic integral holographic imaging.

  19. Joint Power and Multiple Access Control for Wireless Mesh Network with Rose Projection Method

    PubMed Central

    Tang, Meiqin; Shang, Lili; Xin, Yalin; Liu, Xiaohua; Wei, Xinjiang

    2014-01-01

    This paper investigates the utility maximization problem for the downlink of the multi-interface multichannel wireless mesh network with orthogonal frequency division multiple access. A cross-layer joint power and multiple access control algorithm are proposed. Rosen projection matrix is combined with Solodov projection techniques to build a three-memory gradient Rosen projection method, which is applied to solve this optimization problem. The convergence analysis is given and simulations show that the proposed solution achieves significant throughput compared with existing approaches. PMID:24883384

  20. Finite-element methods for spatially resolved mesoscopic electron transport

    NASA Astrophysics Data System (ADS)

    Kramer, Stephan

    2013-09-01

    A finite-element method is presented for calculating the quantum conductance of mesoscopic two-dimensional electron devices of complex geometry attached to semi-infinite leads. For computational purposes, the leads must be cut off at some finite length. To avoid spurious, unphysical reflections, this is modeled by transparent boundary conditions. We introduce the Hardy space infinite-element technique from acoustic scattering as a way of setting up transparent boundary conditions for transport computations spanning the range from the quantum mechanical to the quasiclassical regime. These boundary conditions are exact even for wave packets and thus are especially useful in the limit of high energies with many excited modes. Yet, they possess a memory-friendly sparse matrix representation. In addition to unbounded domains, Hardy space elements allow us to truncate those parts of the computational domain which are irrelevant for the calculation of the transport properties. Thus, the computation can be done only on the region that is essential for a physically meaningful simulation of the scattering states. The benefits of the method are demonstrated by three examples. The convergence properties are tested on the transport through a quasi-one-dimensional quantum wire. It is shown that higher-order finite elements considerably improve current conservation and establish the correct phase shift between the real and the imaginary parts of the electron wave function. The Aharonov-Bohm effect demonstrates that characteristic features of quantum interference can be assessed. A simulation of electron magnetic focusing exemplifies the capability of the computational framework to study the crossover from quantum to quasiclassical behavior.

  1. Revealing cryptic spatial patterns in genetic variability by a new multivariate method.

    PubMed

    Jombart, T; Devillard, S; Dufour, A-B; Pontier, D

    2008-07-01

    Increasing attention is being devoted to taking landscape information into account in genetic studies. Among landscape variables, space is often considered as one of the most important. To reveal spatial patterns, a statistical method should be spatially explicit, that is, it should directly take spatial information into account as a component of the adjusted model or of the optimized criterion. In this paper we propose a new spatially explicit multivariate method, spatial principal component analysis (sPCA), to investigate the spatial pattern of genetic variability using allelic frequency data of individuals or populations. This analysis does not require data to meet Hardy-Weinberg expectations or linkage equilibrium to exist between loci. The sPCA yields scores summarizing both the genetic variability and the spatial structure among individuals (or populations). Global structures (patches, clines and intermediates) are disentangled from local ones (strong genetic differences between neighbors) and from random noise. Two statistical tests are proposed to detect the existence of both types of patterns. As an illustration, the results of principal component analysis (PCA) and sPCA are compared using simulated datasets and real georeferenced microsatellite data of Scandinavian brown bear individuals (Ursus arctos). sPCA performed better than PCA to reveal spatial genetic patterns. The proposed methodology is implemented in the adegenet package of the free software R. PMID:18446182

  2. Telephone talk: effects of two access methods on phone call success.

    PubMed

    Hanson, Elizabeth K; Goldhammer, Emily; Bethard, Tanya

    2016-09-01

    The slower and unnatural timing of speech inherent to speech-generating devices (SGDs) can be a barrier to successful aided telephone calls. The timing of message delivery when using an SGD may vary depending on the type of access method used. We measured the difference in the success rate of telephone calls made with an SGD either using switch scanning or direct selection with eye gaze. The scripted calls, asking for directions, were placed to 100 randomly selected businesses. Analysis showed a statistically significant difference in the success rate between the two conditions, with eye gaze access resulting in more successful calls. Findings from this study suggest that people who use SGDs for phone calls may improve the timing of message delivery by using eye gaze access compared to switch scanning. PMID:27400281

  3. Comparing the Push-Pull Versus Discard Blood Sample Method From Adult Central Vascular Access Devices.

    PubMed

    Byrne, Dia

    2016-01-01

    This study demonstrates the feasibility of replacing the discard blood sampling method for central vascular access devices with the push-pull method. A comparative, within-subject design was used to evaluate 61 unique, paired blood samples from 1 adult outpatient oncology clinic. A 21-measure laboratory panel was conducted on each of the paired samples. Interpretation showed a small mean bias and excellent agreement between the methods. Blood samples obtained using the push-pull method were within clinically acceptable ranges. No hemolysis was noted by laboratory evaluation of 59 samples. PMID:27074989

  4. EAP-Kerberos: A Low Latency EAP Authentication Method for Faster Handoffs in Wireless Access Networks

    NASA Astrophysics Data System (ADS)

    Zrelli, Saber; Okabe, Nobuo; Shinoda, Yoichi

    The wireless medium is a key technology for enabling ubiquitous and continuous network connectivity. It is becoming more and more important in our daily life especially with the increasing adoption of networking technologies in many fields such as medical care and transportation systems. Although most wireless technologies nowadays provide satisfying bandwidth and higher speeds, several of these technologies still lack improvements with regard to handoff performance. In this paper, we focus on wireless network technologies that rely on the Extensible Authentication Protocol for mutual authentication between the station and the access network. Such technologies include local area wireless networks (IEEE 802.11) as well as broadband wireless networks (IEEE 802.16). We present a new EAP authentication method based on a three party authentication scheme, namely Kerberos, that considerably shortens handoff delays. Compared to other methods, the proposed method has the advantage of not requiring any changes on the access points, making it readily deployable at reasonable costs.

  5. Spatial Statistics Preserving Interpolation Methods for Estimation of Missing Precipitation Data

    NASA Astrophysics Data System (ADS)

    El Sharif, H.; Teegavarapu, R. S.

    2011-12-01

    Spatial interpolation methods used for estimation of missing precipitation data at a site seldom check for their ability to preserve site and regional statistics. Such statistics are primarily defined by spatial correlations and other site-to-site statistics in a region. Preservation of site and regional statistics represents a means of assessing the validity of missing precipitation estimates at a site. This study will evaluate the efficacy of traditional deterministic and stochastic interpolation methods aimed at estimation of missing data in preserving site and regional statistics. New optimal spatial interpolation methods that are intended to preserve these statistics are also proposed and evaluated in this study. Rain gauge sites in the state of Kentucky, USA, are used as a case study for evaluation of existing and newly proposed methods. Several error and performance measures will be used to evaluate the methods and trade-offs in accuracy of estimation and preservation of site and regional statistics.

  6. A Neural Network-Based Optimal Spatial Filter Design Method for Motor Imagery Classification

    PubMed Central

    Yuksel, Ayhan; Olmez, Tamer

    2015-01-01

    In this study, a novel spatial filter design method is introduced. Spatial filtering is an important processing step for feature extraction in motor imagery-based brain-computer interfaces. This paper introduces a new motor imagery signal classification method combined with spatial filter optimization. We simultaneously train the spatial filter and the classifier using a neural network approach. The proposed spatial filter network (SFN) is composed of two layers: a spatial filtering layer and a classifier layer. These two layers are linked to each other with non-linear mapping functions. The proposed method addresses two shortcomings of the common spatial patterns (CSP) algorithm. First, CSP aims to maximize the between-classes variance while ignoring the minimization of within-classes variances. Consequently, the features obtained using the CSP method may have large within-classes variances. Second, the maximizing optimization function of CSP increases the classification accuracy indirectly because an independent classifier is used after the CSP method. With SFN, we aimed to maximize the between-classes variance while minimizing within-classes variances and simultaneously optimizing the spatial filter and the classifier. To classify motor imagery EEG signals, we modified the well-known feed-forward structure and derived forward and backward equations that correspond to the proposed structure. We tested our algorithm on simple toy data. Then, we compared the SFN with conventional CSP and its multi-class version, called one-versus-rest CSP, on two data sets from BCI competition III. The evaluation results demonstrate that SFN is a good alternative for classifying motor imagery EEG signals with increased classification accuracy. PMID:25933101

  7. A neural network-based optimal spatial filter design method for motor imagery classification.

    PubMed

    Yuksel, Ayhan; Olmez, Tamer

    2015-01-01

    In this study, a novel spatial filter design method is introduced. Spatial filtering is an important processing step for feature extraction in motor imagery-based brain-computer interfaces. This paper introduces a new motor imagery signal classification method combined with spatial filter optimization. We simultaneously train the spatial filter and the classifier using a neural network approach. The proposed spatial filter network (SFN) is composed of two layers: a spatial filtering layer and a classifier layer. These two layers are linked to each other with non-linear mapping functions. The proposed method addresses two shortcomings of the common spatial patterns (CSP) algorithm. First, CSP aims to maximize the between-classes variance while ignoring the minimization of within-classes variances. Consequently, the features obtained using the CSP method may have large within-classes variances. Second, the maximizing optimization function of CSP increases the classification accuracy indirectly because an independent classifier is used after the CSP method. With SFN, we aimed to maximize the between-classes variance while minimizing within-classes variances and simultaneously optimizing the spatial filter and the classifier. To classify motor imagery EEG signals, we modified the well-known feed-forward structure and derived forward and backward equations that correspond to the proposed structure. We tested our algorithm on simple toy data. Then, we compared the SFN with conventional CSP and its multi-class version, called one-versus-rest CSP, on two data sets from BCI competition III. The evaluation results demonstrate that SFN is a good alternative for classifying motor imagery EEG signals with increased classification accuracy. PMID:25933101

  8. Device for high spatial resolution chemical analysis of a sample and method of high spatial resolution chemical analysis

    SciTech Connect

    Van Berkel, Gary J.

    2015-10-06

    A system and method for analyzing a chemical composition of a specimen are described. The system can include at least one pin; a sampling device configured to contact a liquid with a specimen on the at least one pin to form a testing solution; and a stepper mechanism configured to move the at least one pin and the sampling device relative to one another. The system can also include an analytical instrument for determining a chemical composition of the specimen from the testing solution. In particular, the systems and methods described herein enable chemical analysis of specimens, such as tissue, to be evaluated in a manner that the spatial-resolution is limited by the size of the pins used to obtain tissue samples, not the size of the sampling device used to solubilize the samples coupled to the pins.

  9. Solving spatial inverse problems using the probability perturbation method: An S-GEMS implementation

    NASA Astrophysics Data System (ADS)

    Li, Ting; Caers, Jef

    2008-09-01

    The probability perturbation method (PPM) is introduced as a flexible and efficient sampling technique for generating inverse solutions under a given prior geological constraint (prior model). In this paper, we present a methodology for producing software code that runs PPM within a public domain geostatistical software called the Stanford Geostatistical Earth Modeling Software (S-GEMS). The challenge in creating such code lies in the great diversity of forward models as well as prior models that can be handled by the PPM. Therefore, our software solution must be highly flexible and extensible such that it can be tailored to the various applications at hand. Our implementation has two main objectives: (1) to create an integrated working environment which provides users easy access to functionalities of the PPM through a general user interface as well as visualize results; (2) allow the users to plug-in their application specific code into the PPM algorithm workflow. We provide a two-part solution. The first part, which is hard-coded in S-GEMS as a plug-in module, runs the Dekker-Brent optimization algorithm to control the parameter perturbation needed for the inversion. It generates the PPM user interface and allows visualization of the spatial domain of interest using S-GEMS graphics capability. The second part is coded in object-oriented Python scripts and is used to control the PPM execution in S-GEMS. Users can program their particular needs in scripts and load them into S-GEMS as part of the PPM workflow. The same mechanism can be used to extend the capabilities of PPM itself by implementing new PPM variants in Python and making them a part of the base class hierarchy. Case studies are used to demonstrate the flexibility of our code. This approach requires the user to adapt only a small amount of python code, without modifying, or re-compiling the core S-GEMS code.

  10. A Method to Access Absolute fIPAR fo Vegetation in Spatially Complex Ecosystems

    NASA Technical Reports Server (NTRS)

    Wessman, Carol A.; Nel, Elizabeth M.; Bateson, C. Ann; Asner, Gregory P.

    1998-01-01

    Arid and semi-arid lands compose a large fraction of the earth's terrestrial vegetation, and thereby contribute significantly to global atmospheric-biospheric interactions. The thorny shrubs and small trees in these semi-arid shrub lands have counterparts throughout much of the world's tropical and subtropical zones and have captured substantial areas of the world's former grasslands. The objective of our field and remotely sensed measurements in the semi-arid shrublands of Texas is to monitor interannual variability and directional change in landscape structure, ecosystem processes and atmosphere-biosphere exchanges. To understand the role ecosystems play in controlling the composition of the atmosphere, it is necessary to quantify processes such as photosynthesis and primary production, decomposition and soil carbon storage, and trace gas exchanges. Photosynthesis is the link whereby surface-atmosphere exchanges such as the radiation balance and exchange of heat, moisture, and gas can be inferred. It also describes the efficiency of carbon dioxide exchange and is directly related to the primary production of vegetation. Our efforts in this paper focus on the indirect, quantification of photosynthesis, and thereby carbon flux and net primary production, via remote sensing and direct measurements of intercepted photosynthetically active radiation (IPAR).

  11. Access to recreational physical activities by car and bus: an assessment of socio-spatial inequalities in mainland Scotland.

    PubMed

    Ferguson, Neil S; Lamb, Karen E; Wang, Yang; Ogilvie, David; Ellaway, Anne

    2013-01-01

    Obesity and other chronic conditions linked with low levels of physical activity (PA) are associated with deprivation. One reason for this could be that it is more difficult for low-income groups to access recreational PA facilities such as swimming pools and sports centres than high-income groups. In this paper, we explore the distribution of access to PA facilities by car and bus across mainland Scotland by income deprivation at datazone level. GIS car and bus networks were created to determine the number of PA facilities accessible within travel times of 10, 20 and 30 minutes. Multilevel negative binomial regression models were then used to investigate the distribution of the number of accessible facilities, adjusting for datazone population size and local authority. Access to PA facilities by car was significantly (p<0.01) higher for the most affluent quintile of area-based income deprivation than for most other quintiles in small towns and all other quintiles in rural areas. Accessibility by bus was significantly lower for the most affluent quintile than for other quintiles in urban areas and small towns, but not in rural areas. Overall, we found that the most disadvantaged groups were those without access to a car and living in the most affluent areas or in rural areas. PMID:23409012

  12. Access to Recreational Physical Activities by Car and Bus: An Assessment of Socio-Spatial Inequalities in Mainland Scotland

    PubMed Central

    Ferguson, Neil S.; Lamb, Karen E.; Wang, Yang; Ogilvie, David; Ellaway, Anne

    2013-01-01

    Obesity and other chronic conditions linked with low levels of physical activity (PA) are associated with deprivation. One reason for this could be that it is more difficult for low-income groups to access recreational PA facilities such as swimming pools and sports centres than high-income groups. In this paper, we explore the distribution of access to PA facilities by car and bus across mainland Scotland by income deprivation at datazone level. GIS car and bus networks were created to determine the number of PA facilities accessible within travel times of 10, 20 and 30 minutes. Multilevel negative binomial regression models were then used to investigate the distribution of the number of accessible facilities, adjusting for datazone population size and local authority. Access to PA facilities by car was significantly (p<0.01) higher for the most affluent quintile of area-based income deprivation than for most other quintiles in small towns and all other quintiles in rural areas. Accessibility by bus was significantly lower for the most affluent quintile than for other quintiles in urban areas and small towns, but not in rural areas. Overall, we found that the most disadvantaged groups were those without access to a car and living in the most affluent areas or in rural areas. PMID:23409012

  13. a Three-Step Spatial-Temporal Clustering Method for Human Activity Pattern Analysis

    NASA Astrophysics Data System (ADS)

    Huang, W.; Li, S.; Xu, S.

    2016-06-01

    How people move in cities and what they do in various locations at different times form human activity patterns. Human activity pattern plays a key role in in urban planning, traffic forecasting, public health and safety, emergency response, friend recommendation, and so on. Therefore, scholars from different fields, such as social science, geography, transportation, physics and computer science, have made great efforts in modelling and analysing human activity patterns or human mobility patterns. One of the essential tasks in such studies is to find the locations or places where individuals stay to perform some kind of activities before further activity pattern analysis. In the era of Big Data, the emerging of social media along with wearable devices enables human activity data to be collected more easily and efficiently. Furthermore, the dimension of the accessible human activity data has been extended from two to three (space or space-time) to four dimensions (space, time and semantics). More specifically, not only a location and time that people stay and spend are collected, but also what people "say" for in a location at a time can be obtained. The characteristics of these datasets shed new light on the analysis of human mobility, where some of new methodologies should be accordingly developed to handle them. Traditional methods such as neural networks, statistics and clustering have been applied to study human activity patterns using geosocial media data. Among them, clustering methods have been widely used to analyse spatiotemporal patterns. However, to our best knowledge, few of clustering algorithms are specifically developed for handling the datasets that contain spatial, temporal and semantic aspects all together. In this work, we propose a three-step human activity clustering method based on space, time and semantics to fill this gap. One-year Twitter data, posted in Toronto, Canada, is used to test the clustering-based method. The results show that the

  14. Data Updating Methods for Spatial Data Infrastructure that Maintain Infrastructure Quality and Enable its Sustainable Operation

    NASA Astrophysics Data System (ADS)

    Murakami, S.; Takemoto, T.; Ito, Y.

    2012-07-01

    The Japanese government, local governments and businesses are working closely together to establish spatial data infrastructures in accordance with the Basic Act on the Advancement of Utilizing Geospatial Information (NSDI Act established in August 2007). Spatial data infrastructures are urgently required not only to accelerate computerization of the public administration, but also to help restoration and reconstruction of the areas struck by the East Japan Great Earthquake and future disaster prevention and reduction. For construction of a spatial data infrastructure, various guidelines have been formulated. But after an infrastructure is constructed, there is a problem of maintaining it. In one case, an organization updates its spatial data only once every several years because of budget problems. Departments and sections update the data on their own without careful consideration. That upsets the quality control of the entire data system and the system loses integrity, which is crucial to a spatial data infrastructure. To ensure quality, ideally, it is desirable to update data of the entire area every year. But, that is virtually impossible, considering the recent budget crunch. The method we suggest is to update spatial data items of higher importance only in order to maintain quality, not updating all the items across the board. We have explored a method of partially updating the data of these two geographical features while ensuring the accuracy of locations. Using this method, data on roads and buildings that greatly change with time can be updated almost in real time or at least within a year. The method will help increase the availability of a spatial data infrastructure. We have conducted an experiment on the spatial data infrastructure of a municipality using those data. As a result, we have found that it is possible to update data of both features almost in real time.

  15. System and Method for Providing Model-Based Alerting of Spatial Disorientation to a Pilot

    NASA Technical Reports Server (NTRS)

    Conner, Kevin J (Inventor); Mathan, Santosh (Inventor); Johnson, Steve (Inventor)

    2015-01-01

    A system and method monitor aircraft state parameters, for example, aircraft movement and flight parameters, applies those inputs to a spatial disorientation model, and makes a prediction of when pilot may become spatially disoriented. Once the system predicts a potentially disoriented pilot, the sensitivity for alerting the pilot to conditions exceeding a threshold can be increased and allow for an earlier alert to mitigate the possibility of an incorrect control input.

  16. A single channel spatial polarization encoding and decoding method based on photoelastic modulator

    NASA Astrophysics Data System (ADS)

    Han, Jie; Zeng, Aijun; Feng, Chunxia; Zhou, Guangchao; Huang, Huijie; Qian, Hongbing

    2009-11-01

    A method to encode and decode the spatial position using polarization is proposed. Birefringent wedge and photoelastic modulator (PEM) are used to encode and modulate the laser with a polarizer and an analyzer. The state of polarization (SOP) of laser beam changes gradually along the gradient direction of birefringent wedge. The spatial polarization encoding beam is transmitted by a beam expander to form a spatial encoding field. A part of laser carrying the information of spatial position in the field is received by detector. With signal processing, the harmonic terms of detected intensity are obtained to realize the single channel decoding. With the single channel spatial polarization encoding and decoding method, the problem of incorporating automatic gain control (AGC) between separate channel signals can be overcome and the precision of decoding is improved by its rotation-invariant feature, and the results of decoding vary linearly with retardation in the range of +/-180°. In experiments, the relationship between decoding spatial position and the true value of position is linear. Usefulness of the method is verified.

  17. Object-oriented urban 3D spatial data model organization method

    NASA Astrophysics Data System (ADS)

    Li, Jing-wen; Li, Wen-qing; Lv, Nan; Su, Tao

    2015-12-01

    This paper combined the 3d data model with object-oriented organization method, put forward the model of 3d data based on object-oriented method, implemented the city 3d model to quickly build logical semantic expression and model, solved the city 3d spatial information representation problem of the same location with multiple property and the same property with multiple locations, designed the space object structure of point, line, polygon, body for city of 3d spatial database, and provided a new thought and method for the city 3d GIS model and organization management.

  18. Action research to improve methods of delivery and feedback in an Access Grid Room environment

    NASA Astrophysics Data System (ADS)

    McArthur, Lynne C.; Klass, Lara; Eberhard, Andrew; Stacey, Andrew

    2011-12-01

    This article describes a qualitative study which was undertaken to improve the delivery methods and feedback opportunity in honours mathematics lectures which are delivered through Access Grid Rooms. Access Grid Rooms are facilities that provide two-way video and audio interactivity across multiple sites, with the inclusion of smart boards. The principal aim was to improve the student learning experience, given the new environment. The specific aspects of the course delivery that the study focused on included presentation of materials and provision of opportunities for interaction between the students and between students and lecturers. The practical considerations in the delivery of distance learning are well documented in the literature, and similar problems arise in the Access Grid Room environment; in particular, those of limited access to face-to-face interaction and the reduction in peer support. The nature of the Access Grid Room classes implies that students studying the same course can be physically situated in different cities, and possibly in different countries. When studying, it is important that students have opportunity to discuss new concepts with others; particularly their peers and their lecturer. The Access Grid Room environment also presents new challenges for the lecturer, who must learn new skills in the delivery of materials. The unique nature of Access Grid Room technology offers unprecedented opportunity for effective course delivery and positive outcomes for students, and was developed in response to a need to be able to interact with complex data, other students and the instructor, in real-time, at a distance and from multiple sites. This is a relatively new technology and as yet there has been little or no studies specifically addressing the use and misuse of the technology. The study found that the correct placement of cameras and the use of printed material and smart boards were all crucial to the student experience. In addition, the

  19. Simple and accessible analytical methods for the determination of mercury in soil and coal samples.

    PubMed

    Park, Chul Hee; Eom, Yujin; Lee, Lauren Jong-Eun; Lee, Tai Gyu

    2013-09-01

    Simple and accessible analytical methods compared to conventional methods such as US EPA Method 7471B and ASTM-D6414 for the determination of mercury (Hg) in soil and coal samples are proposed. The new methods are consisted of fewer steps without the Hg oxidizing step consequently eliminating a step necessary to reduce excess oxidant. In the proposed methods, a Hg extraction is an inexpensive and accessible step utilizing a disposable test tube and a heating block instead of an expensive autoclave vessel and a specially-designed microwave. Also, a common laboratory vacuum filtration was used for the extracts instead of centrifugation. As for the optimal conditions, first, best acids for extracting Hg from soil and coal samples was investigated using certified reference materials (CRMs). Among common laboratory acids (HCl, HNO3, H2SO4, and aqua regia), aqua regia was most effective for the soil CRM whereas HNO3 was for the coal CRM. Next, the optimal heating temperature and time for Hg extraction were evaluated. The most effective Hg extraction was obtained at 120°C for 30min for soil CRM and at 70°C for 90min for coal CRM. Further tests using selected CRMs showed that all the measured values were within the allowable certification range. Finally, actual soil and coal samples were analyzed using the new methods and the US EPA Method 7473. The relative standard deviation values of 1.71-6.55% for soil and 0.97-12.11% for coal samples were obtained proving that the proposed methods were not only simple and accessible but also accurate. PMID:23683353

  20. Validation of the intrinsic spatial efficiency method for non cylindrical homogeneous sources using MC simulation

    NASA Astrophysics Data System (ADS)

    Ortiz-Ramírez, Pablo; Ruiz, Andrés

    2016-07-01

    The Monte Carlo simulation of the gamma spectroscopy systems is a common practice in these days. The most popular softwares to do this are MCNP and Geant4 codes. The intrinsic spatial efficiency method is a general and absolute method to determine the absolute efficiency of a spectroscopy system for any extended sources, but this was only demonstrated experimentally for cylindrical sources. Due to the difficulty that the preparation of sources with any shape represents, the simplest way to do this is by the simulation of the spectroscopy system and the source. In this work we present the validation of the intrinsic spatial efficiency method for sources with different geometries and for photons with an energy of 661.65 keV. In the simulation the matrix effects (the auto-attenuation effect) are not considered, therefore these results are only preliminaries. The MC simulation is carried out using the FLUKA code and the absolute efficiency of the detector is determined using two methods: the statistical count of Full Energy Peak (FEP) area (traditional method) and the intrinsic spatial efficiency method. The obtained results show total agreement between the absolute efficiencies determined by the traditional method and the intrinsic spatial efficiency method. The relative bias is lesser than 1% in all cases.

  1. INTEGRATION OF SPATIAL DATA: EVALUATION OF METHODS BASED ON DATA ISSUES AND ASSESSMENT QUESTIONS

    EPA Science Inventory

    EPA's Regional Vulnerability Assessment (ReVA) Program has focused initially on the synthesis of existing data. We have used the same set of spatial data and synthesized these data using a total of 11 existing and newly developed integration methods. These methods were evaluated ...

  2. Estimation of missing rainfall data in Pahang using modified spatial interpolation weighting methods

    NASA Astrophysics Data System (ADS)

    Azman, Muhammad Az-zuhri; Zakaria, Roslinazairimah; Ahmad Radi, Noor Fadhilah

    2015-02-01

    In meteorological and hydrological researches, missing rainfall data always become one of the challenging problems which need to be faced by the researchers. The problems of missing rainfall data are due to the wrong technique used when measuring the rainfall, relocation of the rain station and malfunctioned of instrument. Finding the suitable method to solve the missing data problem is very critical before going to the next level of data analysis. Most researchers used the spatial interpolation method to estimate the missing rainfall data at a particular target station which is based on the available rainfall data at their neighboring stations. The spatial interpolation method is one of the traditional weighting factors which also consider the strength of correlation between stations. This study uses the modified of spatial interpolation weighting methods to estimate the missing rainfall data in Pahang and only assume that the particular target station has the missing value. A new modified method of normal ratio and inverse distance weighting with correlation method is proposed by including the correlation coefficient and abbreviated by NRIDC. The performance of the modified spatial interpolation weighting methods used are assessed using the similarity index (S-index), mean absolute error (MAE) and coefficient of correlation (R) for different percentage of missing values (5%-30%).

  3. Occlusion culling and calculation for a computer generated hologram using spatial frequency index method

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Huang, Yingqing; Yan, Xingpeng; Jiang, Xiaoyu

    2015-10-01

    A spatial frequency index method is proposed to cull occlusion and generate a hologram. Object points with the same spatial frequency are put into a set for their mutual occlusion. The hidden surfaces of the three-dimensional (3D) scene are quickly removed through culling the object points that are furthest from the hologram plane in the set. The phases of plane wave, which are only interrelated with the spatial frequencies, are precomputed and stored in a table. According to the spatial frequency of the object points, the phases of plane wave for generating fringes are obtained directly from the table. Three 3D scenes are chosen to verify the spatial frequency index method. Both numerical simulation and optical reconstruction are performed. Experimental results demonstrate that the proposed method can cull the hidden surfaces of the 3D scene correctly. The occlusion effect of the 3D scene can be well reproduced. The computational speed is better than that obtained using conventional methods but is still time-consuming.

  4. Spatial capture-recapture: a promising method for analyzing data collected using artificial cover objects

    USGS Publications Warehouse

    Sutherland, Chris; Munoz, David; Miller, David A.W.; Grant, Evan

    2016-01-01

    Spatial capture–recapture (SCR) is a relatively recent development in ecological statistics that provides a spatial context for estimating abundance and space use patterns, and improves inference about absolute population density. SCR has been applied to individual encounter data collected noninvasively using methods such as camera traps, hair snares, and scat surveys. Despite the widespread use of capture-based surveys to monitor amphibians and reptiles, there are few applications of SCR in the herpetological literature. We demonstrate the utility of the application of SCR for studies of reptiles and amphibians by analyzing capture–recapture data from Red-Backed Salamanders, Plethodon cinereus, collected using artificial cover boards. Using SCR to analyze spatial encounter histories of marked individuals, we found evidence that density differed little among four sites within the same forest (on average, 1.59 salamanders/m2) and that salamander detection probability peaked in early October (Julian day 278) reflecting expected surface activity patterns of the species. The spatial scale of detectability, a measure of space use, indicates that the home range size for this population of Red-Backed Salamanders in autumn was 16.89 m2. Surveying reptiles and amphibians using artificial cover boards regularly generates spatial encounter history data of known individuals, which can readily be analyzed using SCR methods, providing estimates of absolute density and inference about the spatial scale of habitat use.

  5. Massive spatial data materialization method based on ArcGIS engine

    NASA Astrophysics Data System (ADS)

    Shi, Lihong; Li, Haiyong

    2009-10-01

    With the application of geographic information becoming more extensive, spatial data model based on geographical entities begins to be built and developed. Spatial data model based on entities is a new generation combining object-oriented technology with GIS technology. And it is the future trends of the spatial data model development. It effectively integrates spatial data with attribute data to express the geographic entities which are objective existence. This method takes great advantages to deal with the complex geographical phenomenon. In this paper, through the research of the geographical entity data model, the method of massive spatial data entity building based on ArcGIS Engine is proposed. According to the characteristics of national fundamental geographic information data, we carry out the materialization operation to the data and establish the geographic entity database of national fundamental information. And we apply the results in e-government geographic information general platform. The experiment results show that the spatial entities data is more humanistic in the expression for the objective world and more suitable for the trend of GIS application to popular.

  6. A simple method for correcting spatially resolved solar intensity oscillation observations for variations in scattered light

    NASA Technical Reports Server (NTRS)

    Jefferies, S. M.; Duvall, T. L., Jr.

    1991-01-01

    A measurement of the intensity distribution in an image of the solar disk will be corrupted by a spatial redistribution of the light that is caused by the earth's atmosphere and the observing instrument. A simple correction method is introduced here that is applicable for solar p-mode intensity observations obtained over a period of time in which there is a significant change in the scattering component of the point spread function. The method circumvents the problems incurred with an accurate determination of the spatial point spread function and its subsequent deconvolution from the observations. The method only corrects the spherical harmonic coefficients that represent the spatial frequencies present in the image and does not correct the image itself.

  7. Violent crime in San Antonio, Texas: an application of spatial epidemiological methods.

    PubMed

    Sparks, Corey S

    2011-12-01

    Violent crimes are rarely considered a public health problem or investigated using epidemiological methods. But patterns of violent crime and other health conditions are often affected by similar characteristics of the built environment. In this paper, methods and perspectives from spatial epidemiology are used in an analysis of violent crimes in San Antonio, TX. Bayesian statistical methods are used to examine the contextual influence of several aspects of the built environment. Additionally, spatial regression models using Bayesian model specifications are used to examine spatial patterns of violent crime risk. Results indicate that the determinants of violent crime depend on the model specification, but are primarily related to the built environment and neighborhood socioeconomic conditions. Results are discussed within the context of a rapidly growing urban area with a diverse population. PMID:22748228

  8. Analysis of the glucagon receptor first extracellular loop by the substituted cysteine accessibility method.

    PubMed

    Roberts, David J; Vertongen, Pascale; Waelbroeck, Magali

    2011-08-01

    Glucagon is an important hormone for the prevention of hypoglycemia, and contributes to the hyperglycemia observed in diabetic patients, yet very little is known about its receptor structure and the receptor-glucagon interaction. In related receptors, the first extracellular loop, ECL1, is highly variable in length and sequence, suggesting that it might participate in ligand recognition. We applied a variant of the SCAM (Substituted Cysteine Accessibility Method) to the glucagon receptor ECL1 and sequentially mutated positions 197 to 223 to cysteine. Most of the mutations (15/27) affected the glucagon potency, due either to a modification of the glucagon binding site, or to the destabilization of the active receptor conformation. We reasoned that side chains accessible to glucagon must also be accessible to large, hydrophilic cysteine reagents. We therefore evaluated the accessibility of the introduced cysteines to maleimide-PEO(2)-biotin ((+)-biotinyl-3-maleimido-propionamidyl-3,6-dioxa-octanediamine), and tested the effect of pretreatment of intact cells with a large cationic cysteine reagent, MTSET ([2-(trimethylammonium)ethyl]methanethiosulfonate bromide), on glucagon potency. Our results suggest that the second and third transmembrane helices (TM2 and TM3) are extended to position 202 and from position 215, respectively, and separated by a short β stretch (positions 203-209). Glucagon binding induced a conformational change close to TM2: L198C was accessible to the biotin reagent only in the presence of glucagon. Most other mutations affected the receptor activation rather than glucagon recognition, but S217 and D218 (at the top of TM3) were good candidates for glucagon recognition and V221 was very close to the binding site. PMID:21704096

  9. Differences in Food Environment Perceptions and Spatial Attributes of Food Shopping between Residents of Low and High Food Access Areas

    PubMed Central

    Sohi, Inderbir; Bell, Bethany A.; Liu, Jihong; Battersby, Sarah E.; Liese, Angela D.

    2014-01-01

    Objective To explore potential differences in food shopping behaviors and healthy food availability perceptions between residents living in areas with low and high food access. Design A cross-sectional telephone survey to assess food shopping behaviors and perceptions. Data from an eight-county food environment field census used to define the CDC (Centers for Disease Control and Prevention) healthier food retail tract and USDA ERS (United States Department of Agriculture Economic Research Service) food desert measure. Participants 968 residents in eight South Carolina counties. Main Outcome Measures Residents’ food shopping behaviors and healthy food availability perceptions. Analysis Linear and logistic regression. Results Compared to residents in high food access areas, residents in low food access areas traveled further to their primary food store (USDA ERS: 8.8 vs. 7.1 miles, p=0.03; CDC: 9.2 vs. 6.1 miles, p<0.001), accumulated more total shopping miles per week; CDC 28.0 vs. 15.4 miles, p<0.001) and showed differences in perceived healthy food availability (p<0.001) and shopping access (p<0.001). Conclusions and Implications These findings lend support to ongoing community and policy interventions aimed at reducing food access disparities. PMID:24560861

  10. A stochastic simulation method for the assessment of resistive random access memory retention reliability

    SciTech Connect

    Berco, Dan Tseng, Tseung-Yuen

    2015-12-21

    This study presents an evaluation method for resistive random access memory retention reliability based on the Metropolis Monte Carlo algorithm and Gibbs free energy. The method, which does not rely on a time evolution, provides an extremely efficient way to compare the relative retention properties of metal-insulator-metal structures. It requires a small number of iterations and may be used for statistical analysis. The presented approach is used to compare the relative robustness of a single layer ZrO{sub 2} device with a double layer ZnO/ZrO{sub 2} one, and obtain results which are in good agreement with experimental data.

  11. A stochastic simulation method for the assessment of resistive random access memory retention reliability

    NASA Astrophysics Data System (ADS)

    Berco, Dan; Tseng, Tseung-Yuen

    2015-12-01

    This study presents an evaluation method for resistive random access memory retention reliability based on the Metropolis Monte Carlo algorithm and Gibbs free energy. The method, which does not rely on a time evolution, provides an extremely efficient way to compare the relative retention properties of metal-insulator-metal structures. It requires a small number of iterations and may be used for statistical analysis. The presented approach is used to compare the relative robustness of a single layer ZrO2 device with a double layer ZnO/ZrO2 one, and obtain results which are in good agreement with experimental data.

  12. System and method for integrating and accessing multiple data sources within a data warehouse architecture

    DOEpatents

    Musick, Charles R.; Critchlow, Terence; Ganesh, Madhaven; Slezak, Tom; Fidelis, Krzysztof

    2006-12-19

    A system and method is disclosed for integrating and accessing multiple data sources within a data warehouse architecture. The metadata formed by the present method provide a way to declaratively present domain specific knowledge, obtained by analyzing data sources, in a consistent and useable way. Four types of information are represented by the metadata: abstract concepts, databases, transformations and mappings. A mediator generator automatically generates data management computer code based on the metadata. The resulting code defines a translation library and a mediator class. The translation library provides a data representation for domain specific knowledge represented in a data warehouse, including "get" and "set" methods for attributes that call transformation methods and derive a value of an attribute if it is missing. The mediator class defines methods that take "distinguished" high-level objects as input and traverse their data structures and enter information into the data warehouse.

  13. Methods, compositions and kits for imaging cells and tissues using nanoparticles and spatial frequency heterodyne imaging

    DOEpatents

    Rose-Petruck, Christoph; Wands, Jack R.; Rand, Danielle; Derdak, Zoltan; Ortiz, Vivian

    2016-04-19

    Methods, compositions, systems, devices and kits are provided herein for preparing and using a nanoparticle composition and spatial frequency heterodyne imaging for visualizing cells or tissues. In various embodiments, the nanoparticle composition includes at least one of: a nanoparticle, a polymer layer, and a binding agent, such that the polymer layer coats the nanoparticle and is for example a polyethylene glycol, a polyelectrolyte, an anionic polymer, or a cationic polymer, and such that the binding agent that specifically binds the cells or the tissue. Methods, compositions, systems, devices and kits are provided for identifying potential therapeutic agents in a model using the nanoparticle composition and spatial frequency heterodyne imaging.

  14. Electrochemical impedance spectroscopy system and methods for determining spatial locations of defects

    DOEpatents

    Glenn, David F.; Matthern, Gretchen E.; Propp, W. Alan; Glenn, Anne W.; Shaw, Peter G.

    2006-08-08

    A method and apparatus for determining spatial locations of defects in a material are described. The method includes providing a plurality of electrodes in contact with a material, applying a sinusoidal voltage to a select number of the electrodes at a predetermined frequency, determining gain and phase angle measurements at other of the electrodes in response to applying the sinusoidal voltage to the select number of electrodes, determining impedance values from the gain and phase angle measurements, computing an impedance spectrum for an area of the material from the determined impedance values, and comparing the computed impedance spectrum with a known impedance spectrum to identify spatial locations of defects in the material.

  15. An Indoor Space Partition Method and its Fingerprint Positioning Optimization Considering Pedestrian Accessibility

    NASA Astrophysics Data System (ADS)

    Xu, Yue; Shi, Yong; Zheng, Xingyu; Long, Yi

    2016-06-01

    Fingerprint positioning method is generally the first choice in indoor navigation system due to its high accuracy and low cost. The accuracy depends on partition density to the indoor space. The accuracy will be higher with higher grid resolution. But the high grid resolution leads to significantly increasing work of the fingerprint data collection, processing and maintenance. This also might decrease the performance, portability and robustness of the navigation system. Meanwhile, traditional fingerprint positioning method use equational grid to partition the indoor space. While used for pedestrian navigation, sometimes a person can be located at the area where he or she cannot access. This paper studied these two issues, proposed a new indoor space partition method considering pedestrian accessibility, which can increase the accuracy of pedestrian position, and decrease the volume of the fingerprint data. Based on this proposed partition method, an optimized algorithm for fingerprint position was also designed. A across linker structure was used for fingerprint point index and matching. Experiment based on the proposed method and algorithm showed that the workload of fingerprint collection and maintenance were effectively decreased, and poisoning efficiency and accuracy was effectively increased

  16. Modified shifted angular spectrum method for numerical propagation at reduced spatial sampling rates.

    PubMed

    Ritter, André

    2014-10-20

    The shifted angular spectrum method allows a reduction of the number of samples required for numerical off-axis propagation of scalar wave fields. In this work, a modification of the shifted angular spectrum method is presented. It allows a further reduction of the spatial sampling rate for certain wave fields. We calculate the benefit of this method for spherical waves. Additionally, a working implementation is presented showing the example of a spherical wave propagating through a circular aperture. PMID:25401659

  17. Method and system for spatial data input, manipulation and distribution via an adaptive wireless transceiver

    NASA Technical Reports Server (NTRS)

    Wang, Ray (Inventor)

    2009-01-01

    A method and system for spatial data manipulation input and distribution via an adaptive wireless transceiver. The method and system include a wireless transceiver for automatically and adaptively controlling wireless transmissions using a Waveform-DNA method. The wireless transceiver can operate simultaneously over both the short and long distances. The wireless transceiver is automatically adaptive and wireless devices can send and receive wireless digital and analog data from various sources rapidly in real-time via available networks and network services.

  18. Perceived Barriers Affecting Access to Preventive Dental Services: Application of DEMATEL Method

    PubMed Central

    Bahadori, Mohammadkarim; Ravangard, Ramin; Asghari, Baratali

    2013-01-01

    Background Identifying perceived access barriers to preventive dental services is one of the basic steps to improve the public health. Objectives This study aimed to determine the perceived barriers affecting access to preventive dental services in one of Tehran dental clinics in 2012. Patients and Methods This research was a cross-sectional descriptive-analytical study conducted in one of Tehran dental clinics in 2012 using decision–making trial and evaluation laboratory (DEMATEL) method. The study sample included all patients (100 patients) who had referred to the endodontic treatment department from 26 - 31 May, 2012. The required data were collected using a questionnaire. Collected data were analyzed using SPSS 18.0 and MATLAB 7.9.0 SPSSS 18.0, as well as, some descriptive and analytical tests including Mean, Standard Deviation (SD), and Independent T- Test. Results The five determinants of cost, inconvenience, fear, organization, and patient-dentist relationship were determined as barriers to access to dental services among which the cost and patient-dentist relationship were identified as the first and last priorities with the coordinates (1.4 and 1.4) and (1.25 and -0.65), respectively. Conclusions High cost of dental care has led to not referring patients to the clinic. Oral health costs are too high; however insurance organizations have no commitment to support such services. Policymakers, administrators, and insurance organizations have a major role in improving access to dental services. These decision-makers in making their policies can provide the required financial resources, shift the available resources towards preventive care and periodic checkups, and consider providing proper and sufficient places for dental care facilities. PMID:24578831

  19. New methods for quantifying the spatial storage effect: an illustration with desert annuals.

    PubMed

    Sears, Anna L W; Chesson, Peter

    2007-09-01

    Recent theory supports the long-held proposition that coexistence is promoted by species-specific responses to a spatially varying environment. The underlying coexistence mechanism, the spatial storage effect, can be quantified by the covariance between response to the environment and competition. Here, "competition" is generalized to encompass similar processes such as facilitation and apparent competition. In the present study, we use a model field system of desert annual plants to demonstrate this method and to provide insight into the dynamics of the field system. Specifically, we use neighborhood competition experiments to quantify the spatial storage effect and compare it to the separate (but not mutually exclusive) process of neighborhood-scale resource partitioning. As our basic experimental design has been used frequently in community ecology, these methods can be applied to many existing data sets, as well as future field studies. PMID:17918402

  20. Discharge simulation using downscaled spatial rainfall field by introducing correlation effect in random cascade method

    NASA Astrophysics Data System (ADS)

    Shrestha, R. K.; Tachikawa, Y.; Takara, K.

    2003-04-01

    The simulation of spatial rainfall field based on non-homogenous random cascade method disaggregates a regionally averaged rainfall such as the GCM output. The cascade-generators are used to disaggregate and produce spatial patterns across the region (Over and Gupta, 1996; Chatchai et al. 2000; Tachikawa et al. 2003). However, the disaggregated data is rarely used to produce discharge by using distributed hydrological model. The hesitation to use disaggregated GCM data in discharge simulation is mainly due to lower reliability to reproduce spatial pattern and higher chance of magnitude fluctuation in a few trials of disaggregation. Long term disaggregation results, which are expected to produce true spatial pattern, may not be convenient for practical discharge simulation. A modified method is tested by keeping the volume balanced and forcing the location of cascade generators on the basis of spatial correlation of rainfall field with respect to surround regions. In this method, a reference matrix is prepared, which is calculated for every target grid by summing the multiplication of rainfall magnitude and spatial correlation coefficient of the respective reference grids. The reference matrix is used to adjust the location of random generator in two ways -- hierarchically and statistically. So, this method is designated as Hierarchical and Statistical Adjustment (HSA) method. The HSA method preserves the magnitude of random cascade generators but modifies the location. Unlike the previous non-homogenous random cascade method, this method produced similar spatial patterns as that of ground truth in every realization, which is a clear indication of improved reliability of the disaggregation method from coarse GCM output to a finer resolution as demanded by the hydrological model. The forced volume balance may be justified from the engineering aspect to maintain the same input quantity of rainfall in a watershed for hydrologic simulation purpose. The downscaled data

  1. A New Method for the Spatialization of Forest Cover by Fusing Forest Inventory and MODIS Data

    NASA Astrophysics Data System (ADS)

    Yin, Y.

    2015-12-01

    The acquisition of accurate spatial and temporal data on forest cover is the foundation for the sustainable management and utilization of forest resources. Although forest inventory data can provide accurate statistical information about forest type, such data do not give the specific spatial distribution. Remote sensing data provide accurate spatial information, and vegetation indices provide measures of land surface vegetation cover and growth conditions. By fusing these two sources of data, specific information about the spatial distribution of different types of forest can be obtained. Here, in a case study of Heilongjiang Province, we obtained forest dominant species area from the sixth and seventh national forest inventories and MODIS composite remote sensing data for the same periods to study forest cover by developing a spatialization method. Based on pixel features (such as NDVI and near-infrared reflectance) and their relationships with forest types, thresholds between different forest types in the remote sensing information were set according to the statistical data, which allowed the two sets of data to be fused. As a result, we generated forest cover maps for 2000 and 2005 that show the distribution of four forest types. Taking vegetation map of China as reference data, an error matrix analysis shows that the overall classification consistency reaches 76.7%, but only 70% for evergreen needleleaf forest and mixed forest. This study paves the way for further research on improving the accuracy of forest cover classification accuracy, on expanding the spatial and temporal scales of interest, and on quantifying forest dynamics

  2. Spatial rule-based modeling: a method and its application to the human mitotic kinetochore.

    PubMed

    Ibrahim, Bashar; Henze, Richard; Gruenert, Gerd; Egbert, Matthew; Huwald, Jan; Dittrich, Peter

    2013-01-01

    A common problem in the analysis of biological systems is the combinatorial explosion that emerges from the complexity of multi-protein assemblies. Conventional formalisms, like differential equations, Boolean networks and Bayesian networks, are unsuitable for dealing with the combinatorial explosion, because they are designed for a restricted state space with fixed dimensionality. To overcome this problem, the rule-based modeling language, BioNetGen, and the spatial extension, SRSim, have been developed. Here, we describe how to apply rule-based modeling to integrate experimental data from different sources into a single spatial simulation model and how to analyze the output of that model. The starting point for this approach can be a combination of molecular interaction data, reaction network data, proximities, binding and diffusion kinetics and molecular geometries at different levels of detail. We describe the technique and then use it to construct a model of the human mitotic inner and outer kinetochore, including the spindle assembly checkpoint signaling pathway. This allows us to demonstrate the utility of the procedure, show how a novel perspective for understanding such complex systems becomes accessible and elaborate on challenges that arise in the formulation, simulation and analysis of spatial rule-based models. PMID:24709796

  3. Spatial Rule-Based Modeling: A Method and Its Application to the Human Mitotic Kinetochore

    PubMed Central

    Ibrahim, Bashar; Henze, Richard; Gruenert, Gerd; Egbert, Matthew; Huwald, Jan; Dittrich, Peter

    2013-01-01

    A common problem in the analysis of biological systems is the combinatorial explosion that emerges from the complexity of multi-protein assemblies. Conventional formalisms, like differential equations, Boolean networks and Bayesian networks, are unsuitable for dealing with the combinatorial explosion, because they are designed for a restricted state space with fixed dimensionality. To overcome this problem, the rule-based modeling language, BioNetGen, and the spatial extension, SRSim, have been developed. Here, we describe how to apply rule-based modeling to integrate experimental data from different sources into a single spatial simulation model and how to analyze the output of that model. The starting point for this approach can be a combination of molecular interaction data, reaction network data, proximities, binding and diffusion kinetics and molecular geometries at different levels of detail. We describe the technique and then use it to construct a model of the human mitotic inner and outer kinetochore, including the spindle assembly checkpoint signaling pathway. This allows us to demonstrate the utility of the procedure, show how a novel perspective for understanding such complex systems becomes accessible and elaborate on challenges that arise in the formulation, simulation and analysis of spatial rule-based models. PMID:24709796

  4. Comparison of four spatial interpolation methods for estimating soil moisture in a complex terrain catchment.

    PubMed

    Yao, Xueling; Fu, Bojie; Lü, Yihe; Sun, Feixiang; Wang, Shuai; Liu, Min

    2013-01-01

    Many spatial interpolation methods perform well for gentle terrains when producing spatially continuous surfaces based on ground point data. However, few interpolation methods perform satisfactorily for complex terrains. Our objective in the present study was to analyze the suitability of several popular interpolation methods for complex terrains and propose an optimal method. A data set of 153 soil water profiles (1 m) from the semiarid hilly gully Loess Plateau of China was used, generated under a wide range of land use types, vegetation types and topographic positions. Four spatial interpolation methods, including ordinary kriging, inverse distance weighting, linear regression and regression kriging were used for modeling, randomly partitioning the data set into 2/3 for model fit and 1/3 for independent testing. The performance of each method was assessed quantitatively in terms of mean-absolute-percentage-error, root-mean-square-error, and goodness-of-prediction statistic. The results showed that the prediction accuracy differed significantly between each method in complex terrain. The ordinary kriging and inverse distance weighted methods performed poorly due to the poor spatial autocorrelation of soil moisture at small catchment scale with complex terrain, where the environmental impact factors were discontinuous in space. The linear regression model was much more suitable to the complex terrain than the former two distance-based methods, but the predicted soil moisture changed too sharply near the boundary of the land use types and junction of the sunny (southern) and shady (northern) slopes, which was inconsistent with reality because soil moisture should change gradually in short distance due to its mobility in soil. The most optimal interpolation method in this study for the complex terrain was the hybrid regression kriging, which produced a detailed, reasonable prediction map with better accuracy and prediction effectiveness. PMID:23372749

  5. Comparison of Four Spatial Interpolation Methods for Estimating Soil Moisture in a Complex Terrain Catchment

    PubMed Central

    Yao, Xueling; Fu, Bojie; Lü, Yihe; Sun, Feixiang; Wang, Shuai; Liu, Min

    2013-01-01

    Many spatial interpolation methods perform well for gentle terrains when producing spatially continuous surfaces based on ground point data. However, few interpolation methods perform satisfactorily for complex terrains. Our objective in the present study was to analyze the suitability of several popular interpolation methods for complex terrains and propose an optimal method. A data set of 153 soil water profiles (1 m) from the semiarid hilly gully Loess Plateau of China was used, generated under a wide range of land use types, vegetation types and topographic positions. Four spatial interpolation methods, including ordinary kriging, inverse distance weighting, linear regression and regression kriging were used for modeling, randomly partitioning the data set into 2/3 for model fit and 1/3 for independent testing. The performance of each method was assessed quantitatively in terms of mean-absolute-percentage-error, root-mean-square-error, and goodness-of-prediction statistic. The results showed that the prediction accuracy differed significantly between each method in complex terrain. The ordinary kriging and inverse distance weighted methods performed poorly due to the poor spatial autocorrelation of soil moisture at small catchment scale with complex terrain, where the environmental impact factors were discontinuous in space. The linear regression model was much more suitable to the complex terrain than the former two distance-based methods, but the predicted soil moisture changed too sharply near the boundary of the land use types and junction of the sunny (southern) and shady (northern) slopes, which was inconsistent with reality because soil moisture should change gradually in short distance due to its mobility in soil. The most optimal interpolation method in this study for the complex terrain was the hybrid regression kriging, which produced a detailed, reasonable prediction map with better accuracy and prediction effectiveness. PMID:23372749

  6. Estimation of missing rainfall data using spatial interpolation and imputation methods

    NASA Astrophysics Data System (ADS)

    Radi, Noor Fadhilah Ahmad; Zakaria, Roslinazairimah; Azman, Muhammad Az-zuhri

    2015-02-01

    This study is aimed to estimate missing rainfall data by dividing the analysis into three different percentages namely 5%, 10% and 20% in order to represent various cases of missing data. In practice, spatial interpolation methods are chosen at the first place to estimate missing data. These methods include normal ratio (NR), arithmetic average (AA), coefficient of correlation (CC) and inverse distance (ID) weighting methods. The methods consider the distance between the target and the neighbouring stations as well as the correlations between them. Alternative method for solving missing data is an imputation method. Imputation is a process of replacing missing data with substituted values. A once-common method of imputation is single-imputation method, which allows parameter estimation. However, the single imputation method ignored the estimation of variability which leads to the underestimation of standard errors and confidence intervals. To overcome underestimation problem, multiple imputations method is used, where each missing value is estimated with a distribution of imputations that reflect the uncertainty about the missing data. In this study, comparison of spatial interpolation methods and multiple imputations method are presented to estimate missing rainfall data. The performance of the estimation methods used are assessed using the similarity index (S-index), mean absolute error (MAE) and coefficient of correlation (R).

  7. A spatially adaptive total variation regularization method for electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Song, Xizi; Xu, Yanbin; Dong, Feng

    2015-12-01

    The total variation (TV) regularization method has been used to solve the ill-posed inverse problem of electrical resistance tomography (ERT), owing to its good ability to preserve edges. However, the quality of the reconstructed images, especially in the flat region, is often degraded by noise. To optimize the regularization term and the regularization factor according to the spatial feature and to improve the resolution of reconstructed images, a spatially adaptive total variation (SATV) regularization method is proposed. A kind of effective spatial feature indicator named difference curvature is used to identify which region is a flat or edge region. According to different spatial features, the SATV regularization method can automatically adjust both the regularization term and regularization factor. At edge regions, the regularization term is approximate to the TV functional to preserve the edges; in flat regions, it is approximate to the first-order Tikhonov (FOT) functional to make the solution stable. Meanwhile, the adaptive regularization factor determined by the spatial feature is used to constrain the regularization strength of the SATV regularization method for different regions. Besides, a numerical scheme is adopted for the implementation of the second derivatives of difference curvature to improve the numerical stability. Several reconstruction image metrics are used to quantitatively evaluate the performance of the reconstructed results. Both simulation and experimental results indicate that, compared with the TV (mean relative error 0.288, mean correlation coefficient 0.627) and FOT (mean relative error 0.295, mean correlation coefficient 0.638) regularization methods, the proposed SATV (mean relative error 0.259, mean correlation coefficient 0.738) regularization method can endure a relatively high level of noise and improve the resolution of reconstructed images.

  8. Comparison of spatial interpolation methods for the estimation of precipitation distribution in Distrito Federal, Brazil

    NASA Astrophysics Data System (ADS)

    Borges, Pablo de Amorim; Franke, Johannes; da Anunciação, Yumiko Marina Tanaka; Weiss, Holger; Bernhofer, Christian

    2016-01-01

    Available climatological information of Distrito Federal does not satisfy the requirements for detailed climate diagnosis, as they do not provide the necessary spatial resolution for water resources management purposes. Annual and seasonal climatology (1971-2000) of precipitation from 6 meteorological stations and 54 rain gauges from Central Brazil were used to test eight different spatial interpolation methods. Geographical factors (i.e., altitude, longitude and latitude) explain a large portion of precipitation in the region, and therefore, multivariate models were included. The performance of estimations was assessed through independent validation using mean square error, correlation coefficient and Nash-Sutcliffe efficiency criterion. Inverse distance weighting (IDW), ordinary kriging (OK) and the multivariate regression with interpolation of residuals by IDW (MRegIDW) and OK (MRegOK) have performed the lowest errors and the highest correlation and Nash-Sutcliffe efficiency criterion. In general, interpolation methods provide similar spatial distributions of rainfall wherever observation network is dense. However, the inclusion of geographical variables to the interpolation method should improve estimates in areas where the observation network density is low. Nevertheless, the assessment of uncertainties using a geostatistical method provides supplementary and qualitative information which should be considered when interpreting the spatial distribution of rainfall.

  9. Survey of spatial data needs and land use forecasting methods in the electric utility industry

    NASA Technical Reports Server (NTRS)

    1981-01-01

    A representative sample of the electric utility industry in the United States was surveyed to determine industry need for spatial data (specifically LANDSAT and other remotely sensed data) and the methods used by the industry to forecast land use changes and future energy demand. Information was acquired through interviews, written questionnaires, and reports (both published and internal).

  10. Spatial Visualization Learning in Engineering: Traditional Methods vs. a Web-Based Tool

    ERIC Educational Resources Information Center

    Pedrosa, Carlos Melgosa; Barbero, Basilio Ramos; Miguel, Arturo Román

    2014-01-01

    This study compares an interactive learning manager for graphic engineering to develop spatial vision (ILMAGE_SV) to traditional methods. ILMAGE_SV is an asynchronous web-based learning tool that allows the manipulation of objects with a 3D viewer, self-evaluation, and continuous assessment. In addition, student learning may be monitored, which…

  11. Estimating Small-area Populations by Age and Sex Using Spatial Interpolation and Statistical Inference Methods

    SciTech Connect

    Qai, Qiang; Rushton, Gerald; Bhaduri, Budhendra L; Bright, Eddie A; Coleman, Phil R

    2006-01-01

    The objective of this research is to compute population estimates by age and sex for small areas whose boundaries are different from those for which the population counts were made. In our approach, population surfaces and age-sex proportion surfaces are separately estimated. Age-sex population estimates for small areas and their confidence intervals are then computed using a binomial model with the two surfaces as inputs. The approach was implemented for Iowa using a 90 m resolution population grid (LandScan USA) and U.S. Census 2000 population. Three spatial interpolation methods, the areal weighting (AW) method, the ordinary kriging (OK) method, and a modification of the pycnophylactic method, were used on Census Tract populations to estimate the age-sex proportion surfaces. To verify the model, age-sex population estimates were computed for paired Block Groups that straddled Census Tracts and therefore were spatially misaligned with them. The pycnophylactic method and the OK method were more accurate than the AW method. The approach is general and can be used to estimate subgroup-count types of variables from information in existing administrative areas for custom-defined areas used as the spatial basis of support in other applications.

  12. [Comparison of various spatial interpolation methods for non-stationary regional soil mercury content].

    PubMed

    Hu, Ke-lin; Li, Bao-guo; Lu, Yi-zhong; Zhang, Feng-rong

    2004-05-01

    Accurate delineating of the spatial distribution of soil heavy metal content is essential for pollution assessment and remediation. The objective of this paper is to evaluate various spatial interpolation methods, including ordinary Kriging (OK), simple Kriging (SK), lognormal Kriging (LNK), universal Kriging (UK), disjunctive Kriging (DK) and inverse distance weighting interpolation (IDW) for estimating soil surface Hg content with lognormal distribution, the linear and second-order polynomial trend, and to determine the optimal interpolation method. The predicted errors, statistical feature values and prediction maps obtained by different interpolation methods were compared. The result indicated that first-order trend OK method performed better than both zero and second-order OK methods. Within the method of first-order trend OK, Gaussian semi-variogram model performed better than both the spherical and exponential models. The method using transformed data performed worse than the methods without data transformation because of the 'distortion' effect arising from log transformation. Those with trend effect were better than those without trend effect. First-order trend UK method is the best method among the six methods studied, while the IDW method is the least. PMID:15327270

  13. NMR methods for in-situ biofilm metabolism studies: spatial and temporal resolved measurements

    SciTech Connect

    Majors, Paul D.; Mclean, Jeffrey S.; Fredrickson, Jim K.; Wind, Robert A.

    2005-11-01

    We are developing nuclear magnetic resonance (NMR) microscopy, spectroscopy and combined NMR/optical techniques to the study of biofilms. Objectives include: time and depth-resolved metabolite concentrations with isotropic spatial resolution on the order of 10 microns, metabolic pathways and flux rates, mass transport and ultimately their correlation with gene expression by optical microscopy in biofilms. These methods are being developed with Shewanella oneidensis MR-1 as a model system, but are equally applicable to other biofilm systems of interest. Thus, spatially resolved NMR of biofilms is expected to contribute significantly to the understanding of adherent cell metabolism.

  14. Spatial frequency sampling look-up table method for computer-generated hologram

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Huang, Yingqing; Jiang, Xiaoyu; Yan, Xingpeng

    2016-04-01

    A spatial frequency sampling look-up table method is proposed to generate a hologram. The three-dimensional (3-D) scene is sampled as several intensity images by computer rendering. Each object point on the rendered images has a defined spatial frequency. The basis terms for calculating fringe patterns are precomputed and stored in a table to improve the calculation speed. Both numerical simulations and optical experiments are performed. The results show that the proposed approach can easily realize color reconstructions of a 3-D scene with a low computation cost. The occlusion effects and depth information are all provided accurately.

  15. Dual window method for processing spectroscopic optical coherence tomography signals with high spectral and spatial resolution

    NASA Astrophysics Data System (ADS)

    Robles, Francisco E.; Graf, Robert N.; Wax, Adam

    2009-02-01

    The generation of spectroscopic optical coherence tomography (SOCT) signals suffers from an inherent trade off between spatial and spectral resolution. Here, we present a dual window (DW) method that uses two Gaussian windows to simultaneously obtain high spectral and spatial resolution. We show that the DW method probes the Winger time-frequency distribution (TFD) with two orthogonal windows set by the standard deviation of the Gaussian windows used for processing. We also show that in the limit of an infinitesimally narrow window, combined with a large window, this method is equivalent to the Kirkwood & Richaczek TFD and, if the real part is taken, it is equivalent to the Margenau & Hill (MH) TFD. We demonstrate the effectiveness of the method by simulating a signal with four components separated in depth or center frequency. Six TFD are compared: the ideal, the Wigner, the MH, narrow window short time Fourier transform (STFT), wide window STFT, and the DW. The results show that the DW method contains features of the Wigner TFD, and that it contains the highest spatial and spectral resolution that is free of artifacts. This method can enable powerful applications, including accurate acquisition of the spectral information for cancer diagnosis.

  16. Adaptive spatial carrier frequency method for fast monitoring optical properties of fibres

    NASA Astrophysics Data System (ADS)

    Sokkar, T. Z. N.; El-Farahaty, K. A.; El-Bakary, M. A.; Omar, E. Z.; Agour, M.; Hamza, A. A.

    2016-05-01

    We present an extension of the adaptive spatial carrier frequency method which is proposed for fast measuring optical properties of fibrous materials. The method can be considered as a two complementary steps. In the first step, the support of the adaptive filter shall be defined. In the second step, the angle between the sample under test and the interference fringe system generated by the utilized interferometer has to be determined. Thus, the support of the optical filter associated with the implementation of the adaptive spatial carrier frequency method is accordingly rotated. This method is experimentally verified by measuring optical properties of polypropylene (PP) fibre with the help of a Mach-Zehnder interferometer. The results show that errors resulting from rotating the fibre with respect to the interference fringes of the interferometer are reduced compared with the traditional band pass filter method. This conclusion was driven by comparing results of the mean refractive index of drown PP fibre at parallel polarization direction obtained from the new and adaptive spatial carrier frequency method.

  17. Detection and correction of spectral and spatial misregistrations for hyperspectral data using phase correlation method.

    PubMed

    Yokoya, Naoto; Miyamura, Norihide; Iwasaki, Akira

    2010-08-20

    Hyperspectral imaging sensors suffer from spectral and spatial misregistrations due to optical-system aberrations and misalignments. These artifacts distort spectral signatures that are specific to target objects and thus reduce classification accuracy. The main objective of this work is to detect and correct spectral and spatial misregistrations of hyperspectral images. The Hyperion visible near-infrared subsystem is used as an example. An image registration method based on phase correlation demonstrates the accurate detection of the spectral and spatial misregistrations. Cubic spline interpolation using estimated properties makes it possible to modify the spectral signatures. The accuracy of the proposed postlaunch estimation of the Hyperion characteristics is comparable to that of the prelaunch measurements, which enables the accurate onboard calibration of hyperspectral sensors. PMID:20733628

  18. Beyond the SCS-CN method: A theoretical framework for spatially lumped rainfall-runoff response

    NASA Astrophysics Data System (ADS)

    Bartlett, M. S.; Parolari, A. J.; McDonnell, J. J.; Porporato, A.

    2016-06-01

    Since its introduction in 1954, the Soil Conservation Service curve number (SCS-CN) method has become the standard tool, in practice, for estimating an event-based rainfall-runoff response. However, because of its empirical origins, the SCS-CN method is restricted to certain geographic regions and land use types. Moreover, it does not describe the spatial variability of runoff. To move beyond these limitations, we present a new theoretical framework for spatially lumped, event-based rainfall-runoff modeling. In this framework, we describe the spatially lumped runoff model as a point description of runoff that is upscaled to a watershed area based on probability distributions that are representative of watershed heterogeneities. The framework accommodates different runoff concepts and distributions of heterogeneities, and in doing so, it provides an implicit spatial description of runoff variability. Heterogeneity in storage capacity and soil moisture are the basis for upscaling a point runoff response and linking ecohydrological processes to runoff modeling. For the framework, we consider two different runoff responses for fractions of the watershed area: "prethreshold" and "threshold-excess" runoff. These occur before and after infiltration exceeds a storage capacity threshold. Our application of the framework results in a new model (called SCS-CNx) that extends the SCS-CN method with the prethreshold and threshold-excess runoff mechanisms and an implicit spatial description of runoff. We show proof of concept in four forested watersheds and further that the resulting model may better represent geographic regions and site types that previously have been beyond the scope of the traditional SCS-CN method.

  19. Transverse spatial phase-shifting method used in vibration-compensated interferometer

    NASA Astrophysics Data System (ADS)

    Wu, Dong; Zhu, Ri-Hong; Chen, Lei; Li, Jin-Yun

    Based on the conception of temporal phase-shifting interferometry, we have developed a novel technique named transverse spatial phase-shifting method. Only using four photoelectric detectors with a certain spatial array, the method can directly detect wavefront phase variation due to external vibrations. As soon as wavefront variation was determined, some feedback control could be put on interferometer to compensate the vibrations. This method was applied to a Twyman-Green phase-shifting interferometer in which an adaptive vibration-compensated system has been built, it calibrated wavefront phase in real time by a piezoelectric transducer used as both wavefront phase shifter and vibration feedback device, thus fringe pattern could be stabilized and the optical testing would be carried out. Some experimental results were presented.

  20. Laser speckle imaging of rat retinal blood flow with hybrid temporal and spatial analysis method

    NASA Astrophysics Data System (ADS)

    Cheng, Haiying; Yan, Yumei; Duong, Timothy Q.

    2009-02-01

    Noninvasive monitoring of blood flow in retinal circulation will reveal the progression and treatment of ocular disorders, such as diabetic retinopathy, age-related macular degeneration and glaucoma. A non-invasive and direct BF measurement technique with high spatial-temporal resolution is needed for retinal imaging. Laser speckle imaging (LSI) is such a method. Currently, there are two analysis methods for LSI: spatial statistics LSI (SS-LSI) and temporal statistical LSI (TS-LSI). Comparing these two analysis methods, SS-LSI has higher signal to noise ratio (SNR) and TSLSI is less susceptible to artifacts from stationary speckle. We proposed a hybrid temporal and spatial analysis method (HTS-LSI) to measure the retinal blood flow. Gas challenge experiment was performed and images were analyzed by HTS-LSI. Results showed that HTS-LSI can not only remove the stationary speckle but also increase the SNR. Under 100% O2, retinal BF decreased by 20-30%. This was consistent with the results observed with laser Doppler technique. As retinal blood flow is a critical physiological parameter and its perturbation has been implicated in the early stages of many retinal diseases, HTS-LSI will be an efficient method in early detection of retina diseases.

  1. Obtaining structural and functional information for GPCRs using the substituted-cysteine accessibility method (SCAM).

    PubMed

    Liapakis, George

    2014-01-01

    G-protein coupled receptors (GPCRs) are proteins of the plasma membrane, which are characterized by seven membrane-spanning segments (TMs). GPCRs play an important role in almost all of our physiological and pathophysiological conditions by interacting with a large variety of ligands and stimulating different G-proteins and signaling cascades. By playing a key role in the function of our body and being involved in the pathophysiology of many disorders, GPCRs are very important therapeutic targets. Determination of the structure and function of GPCRs could advance the design of novel receptor-specific drugs against various diseases. A powerful method to obtain structural and functional information for GPCRs is the cysteine substituted accessibility method (SCAM). SCAM is used to systematically map the TM residues of GPCRs and determine their functional role. SCAM can also be used to determine differences in the structures of the TMs in different functional states of GPCRs. PMID:25335535

  2. Spatially and temporally continuous LAI datasets based on the mixed pixel decomposition method.

    PubMed

    Zhao, Jianjun; Wang, Yanying; Zhang, Hongyan; Zhang, Zhengxiang; Guo, Xiaoyi; Yu, Shan; Du, Wala

    2016-01-01

    The leaf area index (LAI) is a key biophysical parameter that determines the state of plant growth. A global LAI has been routinely produced by the Moderate Resolution Imaging Spectro-radiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR). However, the MODIS and AVHRR LAI products cannot be synchronized with the same spatial and temporal resolution. The LAI features are not discernible when a global LAI product is implemented at the regional scale because it has low resolution and different land cover types. To obtain high spatial and temporal resolution of LAI products, an empirical model based on the pixel scale was developed. The approach to generate a long (multi-decade) time series of a 1-km spatial resolution LAI normally integrates both AVHRR and MODIS datasets for different land cover types. In this paper, a regression-based model for generating a vegetation LAI was developed using the AVHRR Global Inventory Modelling and Mapping Studies Normalized Difference Vegetation Index (NDVI), MODIS LAI and land cover as input data; the model was evaluated by using relevant data from the same period data from 2000 to 2006. The results of this method show a good consistency in LAI values retrieved from the AVHRR NDVI and MODIS LAI. This simple method has no specific-limited data requirements and can provide improved spatial and temporal resolution in a region without ground data. PMID:27186480

  3. Comparison of Three Plot Selection Methods for Estimating Change in Temporally Variable, Spatially Clustered Populations.

    SciTech Connect

    Thompson, William L.

    2001-07-01

    Monitoring population numbers is important for assessing trends and meeting various legislative mandates. However, sampling across time introduces a temporal aspect to survey design in addition to the spatial one. For instance, a sample that is initially representative may lose this attribute if there is a shift in numbers and/or spatial distribution in the underlying population that is not reflected in later sampled plots. Plot selection methods that account for this temporal variability will produce the best trend estimates. Consequently, I used simulation to compare bias and relative precision of estimates of population change among stratified and unstratified sampling designs based on permanent, temporary, and partial replacement plots under varying levels of spatial clustering, density, and temporal shifting of populations. Permanent plots produced more precise estimates of change than temporary plots across all factors. Further, permanent plots performed better than partial replacement plots except for high density (5 and 10 individuals per plot) and 25% - 50% shifts in the population. Stratified designs always produced less precise estimates of population change for all three plot selection methods, and often produced biased change estimates and greatly inflated variance estimates under sampling with partial replacement. Hence, stratification that remains fixed across time should be avoided when monitoring populations that are likely to exhibit large changes in numbers and/or spatial distribution during the study period. Key words: bias; change estimation; monitoring; permanent plots; relative precision; sampling with partial replacement; temporary plots.

  4. Chronic restricted access to 10% sucrose solution in adolescent and young adult rats impairs spatial memory and alters sensitivity to outcome devaluation.

    PubMed

    Kendig, Michael D; Boakes, Robert A; Rooney, Kieron B; Corbit, Laura H

    2013-08-15

    Although increasing consumption of sugar drinks is recognized as a significant public health concern, little is known about (a) the cognitive effects resulting from sucrose consumption; and (b) whether the long-term effects of sucrose consumption are more pronounced for adolescents. This experiment directly compared performance on a task of spatial learning and memory (the Morris Water Maze) and sensitivity to outcome devaluation following 28 days of 2-h/day access to a 10% sucrose solution in adolescent and young-adult Wistar rats. Sucrose groups developed elevated fasting blood glucose levels after the diet intervention, despite drawing <15% of calories from sucrose and gaining no more weight than controls. In subsequent behavioral testing, sucrose groups were impaired on the Morris Water Maze, with some residual deficits in spatial memory observed more than 6 weeks after the end of sucrose exposure. Further, results from outcome devaluation testing indicated that in the older cohort of rats, those fed sucrose showed reduced sensitivity to devaluation of the outcome, suggestive of differences in instrumental learning following sucrose exposure. Data provide strong evidence that sucrose consumption can induce deficits in spatial cognition and reward-oriented behavior at levels that resemble patterns of sugar drink consumption in young people, and which can remain long after exposure. PMID:23954407

  5. Accuracy comparison of spatial interpolation methods for estimation of air temperatures in South Korea

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Shim, K.; Jung, M.; Kim, S.

    2013-12-01

    Because of complex terrain, micro- as well as meso-climate variability is extreme by locations in Korea. In particular, air temperature of agricultural fields are influenced by topographic features of the surroundings making accurate interpolation of regional meteorological data from point-measured data. This study was conducted to compare accuracy of a spatial interpolation method to estimate air temperature in Korean Peninsula with the rugged terrains in South Korea. Four spatial interpolation methods including Inverse Distance Weighting (IDW), Spline, Kriging and Cokriging were tested to estimate monthly air temperature of unobserved stations. Monthly measured data sets (minimum and maximum air temperature) from 456 automatic weather station (AWS) locations in South Korea were used to generate the gridded air temperature surface. Result of cross validation showed that using Exponential theoretical model produced a lower root mean square error (RMSE) than using Gaussian theoretical model in case of Kriging and Cokriging and Spline produced the lowest RMSE of spatial interpolation methods in both maximum and minimum air temperature estimation. In conclusion, Spline showed the best accuracy among the methods, but further experiments which reflect topography effects such as temperature lapse rate are necessary to improve the prediction.

  6. Spatial disaggregation of traffic emission inventories in large cities using simplified top-down methods

    NASA Astrophysics Data System (ADS)

    Saide, P.; Zah, R.; Osses, M.; Ossés de Eicker, M.

    Simple, inexpensive and accurate methods for assessing the spatial distribution of traffic emissions are badly needed for the environmental management in South American cities. In this study, various spatial disaggregation methods of traffic emissions of carbon monoxide are presented and evaluated for a large city (Santiago de Chile). Previous methods have used a simplified road network as a proxy for deriving spatial patterns of emissions. However, these approaches resulted in underestimation of emissions in urban centers, industrial zones and highly loaded roads, as well as overestimation in residential zones. Here we modify these methods by adding data correlated with the emissions (e.g. traffic counts, vehicles mean speed, road capacity) solving partially or completely the indicated problems. After an accuracy-simplicity analysis two methodologies stand out over the others: using traffic count classification and using a land use map, both combined with a simplified road network. Both are top-down approaches that correlate well (˜0.9) with the reference emissions and capture emission peaks (within 30% relative error). Hence the proposed changes allow an improved balance between accuracy and costs (monetary, availability of data and time to obtain data).

  7. Image Reconstruction Method with the Exploitation of the Spatial Correlation for Electrical Capacitance Tomography

    NASA Astrophysics Data System (ADS)

    Lei, Jing; Liu, Shi

    2015-12-01

    Electrical capacitance tomography (ECT) is considered to be a competitive measurement method. The imaging objects in ECT measurements are often in a time-varying process, and exploiting the prior information related to the dynamic nature is important for reconstructing high-quality images. Different from existing reconstruction models, in this paper a new model that incorporates the spatial correlation of the pixels by introducing the radial basis function (RBF) method, the dynamic behaviors of a timevarying imaging object, and the ECT measurement information is proposed to formulate the dynamic imaging problem. An objective functional that exploits the spatial correlation of the pixels, the combinational regularizer of the first-order total variation (FOTV) and the second-order total variation (SOTV), the multi-scale regularization, the spatial constraint, and the temporal correlation is proposed to convert the ECT imaging task into an optimization problem. A split Bregman iteration (SBI) method based iteration scheme is developed for solving the proposed objective functional. Numerical simulation results validate the superiority of the proposed reconstruction method on the improvement of the imaging quality.

  8. A fine organization method of spatial geometry data about three-dimensional geographic solid

    NASA Astrophysics Data System (ADS)

    Li, Jing-wen; Xue, Long-li; Wang, Fang; Wang, Ke

    2015-12-01

    With the rise of the wisdom of urban construction, the intelligent city requirements expression to fine the geometric structure of spatial entity, so as to realize the refined analysis of urban geographic information, to achieve the purpose of intelligent management. But the traditional geographic entity geometric data organization method ignores the express geographic entity's internal geometry information,, and can not meet the requirements of the fine analysis. Therefore, it is a problem to be solved that how to make a thorough physical and geometrical data of its spatial geometry. In this paper, we propose a method of organizing the Tetrahedral Network in the geographic entity and combining with hierarchical representation for B-rep model to solve the problem.

  9. Examining the spatial distribution of flower thrips in southern highbush blueberries by utilizing geostatistical methods.

    PubMed

    Rhodes, Elena M; Liburd, Oscar E; Grunwald, Sabine

    2011-08-01

    Flower thrips (Frankliniella spp.) are one of the key pests of southern highbush blueberries (Vaccinium corymbosum L. x V. darrowii Camp), a high-value crop in Florida. Thrips' feeding and oviposition injury to flowers can result in fruit scarring that renders the fruit unmarketable. Flower thrips often form areas of high population, termed "hot spots", in blueberry plantings. The objective of this study was to model thrips spatial distribution patterns with geostatistical techniques. Semivariogram models were used to determine optimum trap spacing and two commonly used interpolation methods, inverse distance weighting (IDW) and ordinary kriging (OK), were compared for their ability to model thrips spatial patterns. The experimental design consisted of a grid of 100 white sticky traps spaced at 15.24-m and 7.61-m intervals in 2008 and 2009, respectively. Thirty additional traps were placed randomly throughout the sampling area to collect information on distances shorter than the grid spacing. The semivariogram analysis indicated that, in most cases, spacing traps at least 28.8 m apart would result in spatially independent samples. Also, the 7.61-m grid spacing captured more of the thrips spatial variability than the 15.24-m grid spacing. IDW and OK produced maps with similar accuracy in both years, which indicates that thrips spatial distribution patterns, including "hot spots," can be modeled using either interpolation method. Future studies can use this information to determine if the formation of "hot spots" can be predicted using flower density, temperature, and other environmental factors. If so, this development would allow growers to spot treat the "hot spots" rather than their entire field. PMID:22251691

  10. Impact of Spatial Interpolation Methods for Precipitation on Ensemble Streamflow Simulation From Watershed Models

    NASA Astrophysics Data System (ADS)

    Hwang, Y.; Clark, M. P.; Rajagopalan, B.

    2005-05-01

    Watershed models are used for simulating basin streamflows based on spatially sparse precipitation and temperature observations. The sparse observations are typically interpolated on a regular grid or a subbasin as inputs to the hydrologic models. Given the paucity in observations and nonhomogenous nature of the precipitation process, differences in interpolation methods can potentially impact the simulated streamflow. Of course, hydrologic model parameter uncertainty also contribute to the errors, but in this paper we focus on the uncertainty due to interpolation methods. To this end, first we developed a two-step process in which the precipitation occurrence is first generated via a logistic regression model, and the amounts are then estimated using a Multiple Linear Regression (MLR) and Locally Weighted Polynomial Regression (LWP). The two-step approach is shown to capture the spatial variability of precipitation effectively than other competing traditional methods. Secondly, interpolated precipitation estimates are input into the watershed model, Precipitation Runoff Modeling System (PRMS) to estimate daily and consequently, monthly and seasonal streamflows. Streamflow estimates from PRMS are obtained for three methods of precipitation interpolation, MLR, LWP and the currently used method in PRMS, Climatological MLR (CMLR). Streamflows are compared on a variety of attributes. We find that the MLR and LWP methods perform much better in simulating the streamflows compared to CMLR. Ensembles of precipitation from the two methods (MLR and LWP) coupled with the logistic regression for precipitation occurrence, are generated to subsequently generate ensembles of streamflows from the watershed model. This approach captures the input uncertainty.

  11. On evaluating the robustness of spatial-proximity-based regionalization methods

    NASA Astrophysics Data System (ADS)

    Lebecherel, Laure; Andréassian, Vazken; Perrin, Charles

    2016-08-01

    In absence of streamflow data to calibrate a hydrological model, its parameters are to be inferred by a regionalization method. In this technical note, we discuss a specific class of regionalization methods, those based on spatial proximity, which transfers hydrological information (typically calibrated parameter sets) from neighbor gauged stations to the target ungauged station. The efficiency of any spatial-proximity-based regionalization method will depend on the density of the available streamgauging network, and the purpose of this note is to discuss how to assess the robustness of the regionalization method (i.e., its resilience to an increasingly sparse hydrometric network). We compare two options: (i) the random hydrometrical reduction (HRand) method, which consists in sub-sampling the existing gauging network around the target ungauged station, and (ii) the hydrometrical desert method (HDes), which consists in ignoring the closest gauged stations. Our tests suggest that the HDes method should be preferred, because it provides a more realistic view on regionalization performance.

  12. A method for the spatial discretization of parabolic equations in one space variable

    SciTech Connect

    Skeel, R.D.; Berzins, M.

    1987-02-01

    The aim of this paper is to describe and analyze a new spatial discretization method for parabolic equations in one space variable: Ordinary and parabolic partial differential equations in one space variable x often have a singularity due to the use of polar cylindrical or spherical coordinates. The method we propose is a simple piecewise nonlinear Galerkin/Petrov-Galerkin method which is second order accurate in space. (It supersedes the method proposed by Skeel). The case m = 1 involves the use of the logarithm function, which is probably the only accurate way to model the logarithmic singularity present in the solution. A code based on a variant of the proposed method has already been included as part of the SPRINT package of Berzins, Dew, and Furzeland. The method that we propose here will be distributed in the next release of the D03P (parabolic equations) section of the NAG Library. 18 refs.

  13. Hotspot detection and spatial distribution of methane emissions from landfills by a surface probe method.

    PubMed

    Gonzalez-Valencia, Rodrigo; Magana-Rodriguez, Felipe; Cristóbal, Jordi; Thalasso, Frederic

    2016-09-01

    A surface probe method previously developed was used to detect hotspots and to determine spatial variation of methane (CH4) emissions from three landfills located in Mexico, with an intermediate or a final cover, as well as with or without a landfill gas collection system. The method was effective in the three landfills and allowed mapping of CH4 emissions with a resolution of 24-64 measurements per hectare, as well as the detection and quantification of hotspots, with a moderate experimental effort. In the three selected landfills, CH4 emissions were quantified to 10, 72, and 575gm(-2)d(-1). Two straightforward parameters describing the spatial distribution of CH4 emissions were also developed. The first parameter provides the percentage of area responsible for a given percentage of total emissions, while the second parameter assigns a numerical value to flux homogeneity. Together, the emissions map and the spatial distribution parameters offer an appropriate tool to landfill operators willing to begin recovering CH4 emissions or to improve the effectiveness of an existing recovery system. This method may therefore help to reduce the greenhouse gas footprint of landfills, which are still the primary option for waste management in developing countries. PMID:26973281

  14. Spatial sound field synthesis and upmixing based on the equivalent source method.

    PubMed

    Bai, Mingsian R; Hsu, Hoshen; Wen, Jheng-Ciang

    2014-01-01

    Given scarce number of recorded signals, spatial sound field synthesis with an extended sweet spot is a challenging problem in acoustic array signal processing. To address the problem, a synthesis and upmixing approach inspired by the equivalent source method (ESM) is proposed. The synthesis procedure is based on the pressure signals recorded by a microphone array and requires no source model. The array geometry can also be arbitrary. Four upmixing strategies are adopted to enhance the resolution of the reproduced sound field when there are more channels of loudspeakers than the microphones. Multi-channel inverse filtering with regularization is exploited to deal with the ill-posedness in the reconstruction process. The distance between the microphone and loudspeaker arrays is optimized to achieve the best synthesis quality. To validate the proposed system, numerical simulations and subjective listening experiments are performed. The results demonstrated that all upmixing methods improved the quality of reproduced target sound field over the original reproduction. In particular, the underdetermined ESM interpolation method yielded the best spatial sound field synthesis in terms of the reproduction error, timbral quality, and spatial quality. PMID:24437767

  15. Intra-Die Spatial Correlation Extraction with Maximum Likelihood Estimation Method for Multiple Test Chips

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Luk, Wai-Shing; Tao, Jun; Zeng, Xuan; Cai, Wei

    In this paper, a novel intra-die spatial correlation extraction method referred to as MLEMTC (Maximum Likelihood Estimation for Multiple Test Chips) is presented. In the MLEMTC method, a joint likelihood function is formulated by multiplying the set of individual likelihood functions for all test chips. This joint likelihood function is then maximized to extract a unique group of parameter values of a single spatial correlation function, which can be used for statistical circuit analysis and design. Moreover, to deal with the purely random component and measurement error contained in measurement data, the spatial correlation function combined with the correlation of white noise is used in the extraction, which significantly improves the accuracy of the extraction results. Furthermore, an LU decomposition based technique is developed to calculate the log-determinant of the positive definite matrix within the likelihood function, which solves the numerical stability problem encountered in the direct calculation. Experimental results have shown that the proposed method is efficient and practical.

  16. Deformation measurement method for spatial complex tubular joints based on photogrammetry

    NASA Astrophysics Data System (ADS)

    Shi, Bao-Quan; Liang, Jin; Xiao, Zhen-Zhong; Zhang, Xiao-Qiang; Liu, Qing

    2010-12-01

    The destruction of spatial complex tubular joints may lead to failure of the whole tubular structure, thus it is necessary to analyze the mechanical properties of spatial complex tubular joint. In this paper, a novel method based on close range photogrammetry to accurately measure the three-dimensional (3D) deformation of spatial complex tubular joints during loading test is proposed. Artificial targets are pasted on the deformation area before loading. The 3D coordinates of these targets are reconstructed by analyzing the images captured at each stage, and the coordinate systems of different stages are registered together by means of global transformation points. The whole field 3D deformation under different load levels is then obtained by tracking the homonymous targets among different stages. It is helpful for further analysis of the mechanical properties. Two different precision evaluation experiments indicate that the proposed method could achieve accuracy of 0.1mm/m. Two full scale tubular joints are tested and a feasible solution for improving the load carrying capacity of the tested tubular joints is thus obtained as per the measured results. For comparison, finite element analysis is employed to predict the deformation in a traditional way. The deformation tendency measured by two methods agrees well.

  17. A Robust Spectrum Sensing Method Based on Maximum Cyclic Autocorrelation Selection for Dynamic Spectrum Access

    NASA Astrophysics Data System (ADS)

    Muraoka, Kazushi; Ariyoshi, Masayuki; Fujii, Takeo

    Spectrum sensing is an important function for dynamic spectrum access (DSA) type cognitive radio systems to detect opportunities for sharing the spectrum with a primary system. The key requirements for spectrum sensing are stability in controlling the probability of false alarm as well as detection performance of the primary signals. However, false alarms can be triggered by noise uncertainty at the secondary devices or unknown interference signals from other secondary systems in realistic radio environments. This paper proposes a robust spectrum sensing method against such uncertainties; it is a kind of cyclostationary feature detection (CFD) approaches. Our proposed method, referred to as maximum cyclic autocorrelation selection (MCAS), compares the peak and non-peak values of the cyclic autocorrelation function (CAF) to detect primary signals, where the non-peak value is the CAF value calculated at cyclic frequencies between the peaks. In MCAS, the desired probability of false alarm can be obtained by setting the number of the non-peak values. In addition, the multiple peak values are combined in MCAS to obtain noise reduction effect and coherent combining gain. Through computer simulations, we show that MCAS can control the probability of false alarm under the condition of noise uncertainty and interference. Furthermore, our method achieves better performance with much less computational complexity in comparison to conventional CFD methods.

  18. Application of spatial methods to identify areas with lime requirement in eastern Croatia

    NASA Astrophysics Data System (ADS)

    Bogunović, Igor; Kisic, Ivica; Mesic, Milan; Zgorelec, Zeljka; Percin, Aleksandra; Pereira, Paulo

    2016-04-01

    With more than 50% of acid soils in all agricultural land in Croatia, soil acidity is recognized as a big problem. Low soil pH leads to a series of negative phenomena in plant production and therefore as a compulsory measure for reclamation of acid soils is liming, recommended on the base of soil analysis. The need for liming is often erroneously determined only on the basis of the soil pH, because the determination of cation exchange capacity, the hydrolytic acidity and base saturation is a major cost to producers. Therefore, in Croatia, as well as some other countries, the amount of liming material needed to ameliorate acid soils is calculated by considering their hydrolytic acidity. For this research, several interpolation methods were tested to identify the best spatial predictor of hidrolitic acidity. The purpose of this study was to: test several interpolation methods to identify the best spatial predictor of hidrolitic acidity; and to determine the possibility of using multivariate geostatistics in order to reduce the number of needed samples for determination the hydrolytic acidity, all with an aim that the accuracy of the spatial distribution of liming requirement is not significantly reduced. Soil pH (in KCl) and hydrolytic acidity (Y1) is determined in the 1004 samples (from 0-30 cm) randomized collected in agricultural fields near Orahovica in eastern Croatia. This study tested 14 univariate interpolation models (part of ArcGIS software package) in order to provide most accurate spatial map of hydrolytic acidity on a base of: all samples (Y1 100%), and the datasets with 15% (Y1 85%), 30% (Y1 70%) and 50% fewer samples (Y1 50%). Parallel to univariate interpolation methods, the precision of the spatial distribution of the Y1 was tested by the co-kriging method with exchangeable acidity (pH in KCl) as a covariate. The soils at studied area had an average pH (KCl) 4,81, while the average Y1 10,52 cmol+ kg-1. These data suggest that liming is necessary

  19. A Method for Improving Temporal and Spatial Resolution of Carbon Dioxide Emissions

    NASA Astrophysics Data System (ADS)

    Gregg, J. S.; Andres, R. J.

    2003-12-01

    Using United States data, a method is developed to estimate the monthly consumption of solid, liquid and gaseous fossil fuels for each state in the union. This technique employs monthly sales data to estimate the relative monthly proportions of the total annual national fossil fuel use. These proportions are then used to estimate the total monthly carbon dioxide emissions for each state. To assess the success of this technique, the results from this method are compared with the data obtained from other independent methods. To determine the temporal success of the method, the resulting national time series is compared to the model produced by Carbon Dioxide Information Analysis Center (CDIAC) and the current model being developed by T. J. Blasing and C. Broniak at the Oak Ridge National Laboratory (ORNL). The University of North Dakota (UND) method fits well temporally with the results of the CDIAC and current ORNL research. To determine the success of the spatial component, the individual state results are compared to the annual state totals calculated by ORNL. Using ordinary least squares regression, the annual state totals of this method are plotted against the ORNL data. This allows a direct comparison of estimates in the form of ordered pairs against a one-to-one ideal correspondence line, and allows for easy detection of outliers in the results obtained by this estimation method. Analyzing the residuals of the linear regression model for each type of fuel permits an improved understanding of the strengths and shortcomings of the spatial component of this estimation technique. Spatially, the model is successful when compared to the current ORNL research. The primary advantages of this method are its ease of implementation and universal applicability. In general, this technique compares favorably to more labor-intensive methods that rely on more detailed data. The more detailed data is generally not available for most countries in the world. The methodology used

  20. Spatial distribution of soil heavy metal pollution estimated by different interpolation methods: accuracy and uncertainty analysis.

    PubMed

    Xie, Yunfeng; Chen, Tong-bin; Lei, Mei; Yang, Jun; Guo, Qing-jun; Song, Bo; Zhou, Xiao-yong

    2011-01-01

    Mapping the spatial distribution of contaminants in soils is the basis of pollution evaluation and risk control. Interpolation methods are extensively applied in the mapping processes to estimate the heavy metal concentrations at unsampled sites. The performances of interpolation methods (inverse distance weighting, local polynomial, ordinary kriging and radial basis functions) were assessed and compared using the root mean square error for cross validation. The results indicated that all interpolation methods provided a high prediction accuracy of the mean concentration of soil heavy metals. However, the classic method based on percentages of polluted samples, gave a pollution area 23.54-41.92% larger than that estimated by interpolation methods. The difference in contaminated area estimation among the four methods reached 6.14%. According to the interpolation results, the spatial uncertainty of polluted areas was mainly located in three types of region: (a) the local maxima concentration region surrounded by low concentration (clean) sites, (b) the local minima concentration region surrounded with highly polluted samples; and (c) the boundaries of the contaminated areas. PMID:20970158

  1. A method for selection of appropriate assistive technology for computer access.

    PubMed

    Jenko, Mojca; Matjacic, Zlatko; Vidmar, Gaj; Bester, Janez; Pogacnikb, Matevz; Zupan, Anton

    2010-12-01

    Assistive technologies (ATs) for computer access enable people with disabilities to be included in the information society. Current methods for assessment and selection of the most appropriate AT for each individual are non standardized, lengthy, subjective, and require substantial clinical experience of a multidisciplinary team.This manuscript presents and evaluates an objective approach to test and select an appropriate AT for computer access for people with disabilities. Six user interfaces(standard keyboard, mini and large joystick, mini and large trackball, and head-operated mouse and keyboard) were tested on the control group of 29 people without disabilities and on 63 people with neuromuscular and muscular diseases, using purpose-built software for testing the speed of sentence typing. Different criteria for selecting the optimal AT were tested and compared with the skilled clinician's choice. The learning curves of the people with disabilities proved to follow those of the healthy controls, but with lower performance. Daily computer use was not associated with AT selection, but corresponded nearly perfectly to the level of functional ability of upper limbs. Agreement between clinician's choice and learning-based AT selection was noteworthy,but far from perfect. If partial agreement was taken into account, that is, AT was considered as an ordinal variable based on the corresponding functional ability level, and the second best learning-based choice was taken into account,the agreement was high for highest median typing speed as AT selection criterion. In conclusion, the developed method for AT assessment and selection seems to be an efficient guide for an unskilled clinician to choose an appropriate AT. PMID:20216223

  2. Cross modulation method of transformation of the spatial coherence of pulsed laser radiation in a nonlinear medium

    SciTech Connect

    Kitsak, M A; Kitsak, A I

    2008-04-30

    The cross modulation method of transformation of the spatial coherence of low-power pulsed laser radiation in a nonlinear medium is proposed. The method is realised experimentally in a multimode optical fibre. The estimates of the degree of spatial coherence of radiation subjected to the phase cross modulation demonstrated the high efficiency of this radiation decorrelation mechanism. (control of laser radiation parameters)

  3. Frequency correction method for improved spatial correlation of hyperpolarized 13C metabolites and anatomy.

    PubMed

    Cunningham, Charles H; Dominguez Viqueira, William; Hurd, Ralph E; Chen, Albert P

    2014-02-01

    Blip-reversed echo-planar imaging (EPI) is investigated as a method for measuring and correcting the spatial shifts that occur due to bulk frequency offsets in (13)C metabolic imaging in vivo. By reversing the k-space trajectory for every other time point, the direction of the spatial shift for a given frequency is reversed. Here, mutual information is used to find the 'best' alignment between images and thereby measure the frequency offset. Time-resolved 3D images of pyruvate/lactate/urea were acquired with 5 s temporal resolution over a 1 min duration in rats (N = 6). For each rat, a second injection was performed with the demodulation frequency purposely mis-set by +35 Hz, to test the correction for erroneous shifts in the images. Overall, the shift induced by the 35 Hz frequency offset was 5.9 ± 0.6 mm (mean ± standard deviation). This agrees well with the expected 5.7 mm shift based on the 2.02 ms delay between k-space lines (giving 30.9 Hz per pixel). The 0.6 mm standard deviation in the correction corresponds to a frequency-detection accuracy of 4 Hz. A method was presented for ensuring the spatial registration between (13)C metabolic images and conventional anatomical images when long echo-planar readouts are used. The frequency correction method was shown to have an accuracy of 4 Hz. Summing the spatially corrected frames gave a signal-to-noise ratio (SNR) improvement factor of 2 or greater, compared with the highest single frame. PMID:24353129

  4. Method and device for maximizing memory system bandwidth by accessing data in a dynamically determined order

    NASA Technical Reports Server (NTRS)

    Wulf, William A. (Inventor); McKee, Sally A. (Inventor); Klenke, Robert (Inventor); Schwab, Andrew J. (Inventor); Moyer, Stephen A. (Inventor); Aylor, James (Inventor); Hitchcock, Charles Young (Inventor)

    2000-01-01

    A data processing system is disclosed which comprises a data processor and memory control device for controlling the access of information from the memory. The memory control device includes temporary storage and decision ability for determining what order to execute the memory accesses. The compiler detects the requirements of the data processor and selects the data to stream to the memory control device which determines a memory access order. The order in which to access said information is selected based on the location of information stored in the memory. The information is repeatedly accessed from memory and stored in the temporary storage until all streamed information is accessed. The information is stored until required by the data processor. The selection of the order in which to access information maximizes bandwidth and decreases the retrieval time.

  5. Early Patient Access to Medicines: Health Technology Assessment Bodies Need to Catch Up with New Marketing Authorization Methods.

    PubMed

    Leyens, Lada; Brand, Angela

    2016-01-01

    National and international medicines agencies have developed innovative methods to expedite promising new medicines to the market and facilitate early patient access. Some of these approval pathways are the conditional approval and the adaptive pathways by the European Medicines Agency (EMA); the Promising Innovative Medicine (PIM) designation and the Early Access to Medicines Scheme (EAMS) by the Medicines and Healthcare Products Regulatory Agency (MHRA), as well as the Fast Track, Breakthrough or Accelerated Approval methods by the Food and Drug Administration (FDA). However, at least in Europe, these methods cannot achieve the goal of improving timely access for patients to new medicines on their own; the reimbursement process also has to become adaptive and flexible. In the past 2 years, the effective access (national patient access) to newly approved oncology drugs ranged from 1 to 30 months, with an extremely high variability between European countries. The goal of early patient access in Europe can only be achieved if the national health technology assessment bodies, such as NICE (ENG), HAS (FR), G-BA (DE) or AIFA (IT), provide harmonized, transparent, flexible, conditional and adaptive methods that adopt the level of evidence accepted by the medicines agencies. The efforts from medicines agencies are welcome but will be in vain if health technology assessments do not follow with similar initiatives, and the European 'postcode' lottery will continue. PMID:27238553

  6. Access to Money and Relation to Women's Use of Family Planning Methods Among Young Married Women in Rural India.

    PubMed

    Reed, Elizabeth; Donta, Balaiah; Dasgupta, Anindita; Ghule, Mohan; Battala, Madhusudana; Nair, Saritha; Silverman, Jay; Jadhav, Arun; Palaye, Prajakta; Saggurti, Niranjan; Raj, Anita

    2016-06-01

    Objectives The social positioning (i.e. social status and autonomy) of women in the household facilitates women's access to and decision-making power related to family planning (FP). Women's access to spending money, which may be an indicator of greater social positioning in the household, may also be greater among women who engage in income generating activities for their families, regardless of women's status in the household. However, in both scenarios, access to money may independently afford greater opportunity to obtain family planning services among women. This study seeks to assess whether access to money is associated with FP outcomes independently of women's social positioning in their households. Methods Using survey data from married couples in rural Maharashtra, India (n = 855), crude and adjusted regression was used to assess women's access to their own spending money in relation to past 3 month use of condoms and other forms of contraceptives (pills, injectables, intrauterine device). Results Access to money (59 %) was associated with condom and other contraceptive use (AORs ranged 1.5-1.8). These findings remained significant after adjusting for women's FP decision-making power in the household and mobility to seek FP services. Conclusion While preliminary, findings suggest that access to money may increase women's ability to obtain FP methods, even in contexts where social norms to support women's power in FP decision-making may not be readily adopted. PMID:26971270

  7. Apparatus for characterizing the temporo-spatial properties of a dynamic fluid front and method thereof

    DOEpatents

    Battiste, Richard L.

    2007-12-25

    Methods and apparatus are described for characterizing the temporal-spatial properties of a dynamic fluid front within a mold space while the mold space is being filled with fluid. A method includes providing a mold defining a mold space and having one or more openings into the mold space; heating a plurality of temperature sensors that extend into the mold space; injecting a fluid into the mold space through the openings, the fluid experiencing a dynamic fluid front while filling the mold space with the fluid; and characterizing temporal-spatial properties of the dynamic fluid front by monitoring a temperature of each of the plurality of heated temperature sensors while the mold space is being filled with the fluid. An apparatus includes a mold defining a mold space; one or more openings for introducing a fluid into the mold space and filling the mold space with the fluid, the fluid experiencing a dynamic fluid front while filling the mold space; a plurality of heated temperature sensors extending into the mold space; and a computer coupled to the plurality of heated temperature sensors for characterizing the temporal-spatial properties of the dynamic fluid front.

  8. Apparatus for characterizing the temporo-spatial properties of a dynamic fluid front and method thereof

    DOEpatents

    Battiste, Richard L

    2013-12-31

    Methods and apparatus are described for characterizing the temporal-spatial properties of a dynamic fluid front within a mold space while the mold space is being filled with fluid. A method includes providing a mold defining a mold space and having one or more openings into the mold space; heating a plurality of temperature sensors that extend into the mold space; injecting a fluid into th emold space through the openings, the fluid experiencing a dynamic fluid front while filling the mold space with a fluid; and characterizing temporal-spatial properties of the dynamic fluid front by monitoring a termperature of each of the plurality of heated temperature sensors while the mold space is being filled with the fluid. An apparatus includes a mold defining a mold space; one or more openings for introducing a fluid into th emold space and filling the mold space with the fluid, the fluid experiencing a dynamic fluid front while filling the mold space; a plurality of heated temperature sensors extending into the mold space; and a computer coupled to the plurality of heated temperature sensors for characterizing the temporal-spatial properties of the dynamic fluid front.

  9. A rainfall design method for spatial flood risk assessment: considering multiple flood sources

    NASA Astrophysics Data System (ADS)

    Jiang, X.; Tatano, H.

    2015-08-01

    Information about the spatial distribution of flood risk is important for integrated urban flood risk management. Focusing on urban areas, spatial flood risk assessment must reflect all risk information derived from multiple flood sources: rivers, drainage, coastal flooding etc. that may affect the area. However, conventional flood risk assessment deals with each flood source independently, which leads to an underestimation of flood risk in the floodplain. Even in floodplains that have no risk from coastal flooding, flooding from river channels and inundation caused by insufficient drainage capacity should be considered simultaneously. For integrated flood risk management, it is necessary to establish a methodology to estimate flood risk distribution across a floodplain. In this paper, a rainfall design method for spatial flood risk assessment, which considers the joint effects of multiple flood sources, is proposed. The concept of critical rainfall duration determined by the concentration time of flooding is introduced to connect response characteristics of different flood sources with rainfall. A copula method is then adopted to capture the correlation of rainfall amount with different critical rainfall durations. Rainfall events are designed taking advantage of the copula structure of correlation and marginal distribution of rainfall amounts within different critical rainfall durations. A case study in the Otsu River Basin, Osaka prefecture, Japan was conducted to demonstrate this methodology.

  10. Spatial and Temporal Simulation of Human Evolution. Methods, Frameworks and Applications

    PubMed Central

    Benguigui, Macarena; Arenas, Miguel

    2014-01-01

    Analyses of human evolution are fundamental to understand the current gradients of human diversity. In this concern, genetic samples collected from current populations together with archaeological data are the most important resources to study human evolution. However, they are often insufficient to properly evaluate a variety of evolutionary scenarios, leading to continuous debates and discussions. A commonly applied strategy consists of the use of computer simulations based on, as realistic as possible, evolutionary models, to evaluate alternative evolutionary scenarios through statistical correlations with the real data. Computer simulations can also be applied to estimate evolutionary parameters or to study the role of each parameter on the evolutionary process. Here we review the mainly used methods and evolutionary frameworks to perform realistic spatially explicit computer simulations of human evolution. Although we focus on human evolution, most of the methods and software we describe can also be used to study other species. We also describe the importance of considering spatially explicit models to better mimic human evolutionary scenarios based on a variety of phenomena such as range expansions, range shifts, range contractions, sex-biased dispersal, long-distance dispersal or admixtures of populations. We finally discuss future implementations to improve current spatially explicit simulations and their derived applications in human evolution. PMID:25132795

  11. BIOMECHANICAL ACCESS METHOD FOR ANALYZING ISOMETRICITY IN RECONSTRUCTING THE MEDIAL PATELLOFEMORAL LIGAMENT

    PubMed Central

    Sadigursky, David; Gobbi, Riccardo Gomes; Pereira, César Augusto Martins; Pécora, José Ricardo; Camanho, Gilberto Luis

    2015-01-01

    Objective: To present a biomechanical device for evaluating medial patellofemoral ligament (MPFL) reconstruction and its isometricity. Methods: An accessible biomechanical method that allowed application of physiological and non-physiological forces to the knee using a mechanical arm and application of weights and counterweights was developed, so as to enable many different evaluations and have a very accurate measurement system for distances between different structures, for analysis on experiments. This article describes the assembly of this system, and suggests some practical applications. Six cadaver knees were studied. The knees were prepared in a testing machine developed at the Biomechanics Laboratory of IOT–HCFMUSP, which allowed dynamic evaluation of patellar behavior, with quantification of patellar lateralization between 0° and 120°. The differences between the distances found with and without load applied to the patella were grouped according to the graft fixation angle (0°, 30°, 60° or 90°) and knee position (intact, damaged or reconstructed). Results: There was a tendency for smaller lateral displacement to occur at fixation angles greater than 30 degrees of flexion, especially between the angles of 45° and 60° degrees of flexion, after the reconstruction. For the other angles, there was no statistical significance. Conclusion: The method developed is a useful tool for studies on the patellofemoral joint and the MPFL, and has a very accurate measurement system for distances between different structures. It can be used in institutions with fewer resources available. PMID:27047872

  12. A ubiquitous method for street scale spatial data collection and analysis in challenging urban environments: mapping health risks using spatial video in Haiti

    PubMed Central

    2013-01-01

    Background Fine-scale and longitudinal geospatial analysis of health risks in challenging urban areas is often limited by the lack of other spatial layers even if case data are available. Underlying population counts, residential context, and associated causative factors such as standing water or trash locations are often missing unless collected through logistically difficult, and often expensive, surveys. The lack of spatial context also hinders the interpretation of results and designing intervention strategies structured around analytical insights. This paper offers a ubiquitous spatial data collection approach using a spatial video that can be used to improve analysis and involve participatory collaborations. A case study will be used to illustrate this approach with three health risks mapped at the street scale for a coastal community in Haiti. Methods Spatial video was used to collect street and building scale information, including standing water, trash accumulation, presence of dogs, cohort specific population characteristics, and other cultural phenomena. These data were digitized into Google Earth and then coded and analyzed in a GIS using kernel density and spatial filtering approaches. The concentrations of these risks around area schools which are sometimes sources of diarrheal disease infection because of the high concentration of children and variable sanitary practices will show the utility of the method. In addition schools offer potential locations for cholera education interventions. Results Previously unavailable fine scale health risk data vary in concentration across the town, with some schools being proximate to greater concentrations of the mapped risks. The spatial video is also used to validate coded data and location specific risks within these “hotspots”. Conclusions Spatial video is a tool that can be used in any environment to improve local area health analysis and intervention. The process is rapid and can be repeated in study

  13. Caveats for the spatial arrangement method: Comment on Hout, Goldinger, and Ferguson (2013).

    PubMed

    Verheyen, Steven; Voorspoels, Wouter; Vanpaemel, Wolf; Storms, Gert

    2016-03-01

    The gold standard among proximity data collection methods for multidimensional scaling is the (dis)similarity rating of pairwise presented stimuli. A drawback of the pairwise method is its lengthy duration, which may cause participants to change their strategy over time, become fatigued, or disengage altogether. Hout, Goldinger, and Ferguson (2013) recently made a case for the Spatial Arrangement Method (SpAM) as an alternative to the pairwise method, arguing that it is faster and more engaging. SpAM invites participants to directly arrange stimuli on a computer screen such that the interstimuli distances are proportional to psychological proximity. Based on a reanalysis of the Hout et al. (2013), data we identify three caveats for SpAM. An investigation of the distributional characteristics of the SpAM proximity data reveals that the spatial nature of SpAM imposes structure on the data, invoking a bias against featural representations. Individual-differences scaling of the SpAM proximity data reveals that the two-dimensional nature of SpAM allows individuals to only communicate two dimensions of variation among stimuli properly, invoking a bias against high-dimensional scaling representations. Monte Carlo simulations indicate that in order to obtain reliable estimates of the group average, SpAM requires more individuals to be tested. We conclude with an overview of considerations that can inform the choice between SpAM and the pairwise method and offer suggestions on how to overcome their respective limitations. PMID:26881991

  14. Comparison of stochastic and deterministic methods for mapping groundwater level spatial variability in sparsely monitored basins.

    PubMed

    Varouchakis, Epsilon A; Hristopulos, D T

    2013-01-01

    In sparsely monitored basins, accurate mapping of the spatial variability of groundwater level requires the interpolation of scattered data. This paper presents a comparison of deterministic interpolation methods, i.e. inverse distance weight (IDW) and minimum curvature (MC), with stochastic methods, i.e. ordinary kriging (OK), universal kriging (UK) and kriging with Delaunay triangulation (DK). The study area is the Mires Basin of Mesara Valley in Crete (Greece). This sparsely sampled basin has limited groundwater resources which are vital for the island's economy; spatial variations of the groundwater level are important for developing management and monitoring strategies. We evaluate the performance of the interpolation methods with respect to different statistical measures. The Spartan variogram family is applied for the first time to hydrological data and is shown to be optimal with respect to stochastic interpolation of this dataset. The three stochastic methods (OK, DK and UK) perform overall better than the deterministic counterparts (IDW and MC). DK, which is herein for the first time applied to hydrological data, yields the most accurate cross-validation estimate for the lowest value in the dataset. OK and UK lead to smooth isolevel contours, whilst DK and IDW generate more edges. The stochastic methods deliver estimates of prediction uncertainty which becomes highest near the southeastern border of the basin. PMID:22311559

  15. Improving Access to Long-Acting Contraceptive Methods and Reducing Unplanned Pregnancy Among Women with Substance Use Disorders

    PubMed Central

    Black, Kirsten I.; Day, Carolyn A.

    2016-01-01

    Much has been written about the consequences of substance use in pregnancy, but there has been far less focus on the prevention of unintended pregnancies in women with substance use disorders (SUDs). We examine the literature on pregnancy incidence for women with SUDs, the clinical and economic benefits of increasing access to long-acting reversible contraceptive (LARC) methods in this population, and the current hurdles to increased access and uptake. High rates of unintended pregnancies and poor physical and psychosocial outcomes among women with SUDs underscore the need for increased access to, and uptake of, LARC methods among these women. A small number of studies that focused on improving access to contraception, especially LARC, via integrated contraception services predominantly provided in drug treatment programs were identified. However, a number of barriers remain, highlighting that much more research is needed in this area. PMID:27199563

  16. Developing a spatial-temporal method for the geographic investigation of shoeprint evidence.

    PubMed

    Lin, Ge; Elmes, Gregory; Walnoha, Mike; Chen, Xiannian

    2009-01-01

    This article examines the potential of a spatial-temporal method for analysis of forensic shoeprint data. The large volume of shoeprint evidence recovered at crime scenes results in varied success in matching a print to a known shoe type and subsequently linking sets of matched prints to suspected offenders. Unlike DNA and fingerprint data, a major challenge is to reduce the uncertainty in linking sets of matched shoeprints to a suspected serial offender. Shoeprint data for 2004 were imported from the Greater London Metropolitan Area Bigfoot database into a geographic information system, and a spatial-temporal algorithm developed for this project. The results show that by using distance and time constraints interactively, the number of candidate shoeprints that can implicate one or few suspects can be substantially reduced. It concludes that the use of space-time and other ancillary information within a geographic information system can be quite helpful for forensic investigation. PMID:19018933

  17. Spatially resolved excitation temperature measurements in a hypersonic flow using the hook method.

    PubMed

    Sandeman, R J; Ebrahim, N A

    1977-05-01

    The extension of the hook method to include spatial resolution of nonuniformities in the test plane as suggested by Huber (1971) and Sandeman (1971) is demonstrated experimentally by measurements of the variation of the integrated line density of ground state sodium in a flame. Experiments are also described in which the variations in the flow of CO(2) in a hypersonic shock tunnel are spatially resolved along the spectrometer slit. The variations in the hook separations of the 425.4-nm Cr1 resonance and the 434.4-nm CrI 1-eV lower state line are simultaneously measured. The chromium exists as an impurity in the hypersonic flow of CO(2) over a cylinder in a shock tunnel. The populations of the levels so obtained have enabled the comparison of the excitation temperature of the Cr 1-eV level with the calculated gas temperature. PMID:20168704

  18. Identification of spatially correlated excitations on a bending plate using the Virtual Fields Method

    NASA Astrophysics Data System (ADS)

    Berry, Alain; Robin, Olivier

    2016-08-01

    This paper aims at identifying the autospectral density and spatial correlation functions of random excitations acting on the surface of a thin plate, from its measured vibration response. The general framework is the Virtual Fields Method (VFM), which was previously applied by the authors to the identification of deterministic excitations on plates. In the present paper, the VFM framework is extended to the case of spatially correlated excitations. It is shown that extraction of the loading power spectral density requires measuring power spectral density functions of transverse displacements and bending curvatures, which can be typically derived from contactless Laser Doppler Vibrometry measurements. The paper details the implementation of the VFM for random excitations, presents numerical simulations and experimental results for diffuse acoustic field excitation of a plate.

  19. Global spatial sensitivity of runoff to subsurface permeability using the active subspace method

    NASA Astrophysics Data System (ADS)

    Gilbert, James M.; Jefferson, Jennifer L.; Constantine, Paul G.; Maxwell, Reed M.

    2016-06-01

    Hillslope scale runoff is generated as a result of interacting factors that include water influx rate, surface and subsurface properties, and antecedent saturation. Heterogeneity of these factors affects the existence and characteristics of runoff. This heterogeneity becomes an increasingly relevant consideration as hydrologic models are extended and employed to capture greater detail in runoff generating processes. We investigate the impact of one type of heterogeneity - subsurface permeability - on runoff using the integrated hydrologic model ParFlow. Specifically, we examine the sensitivity of runoff to variation in three-dimensional subsurface permeability fields for scenarios dominated by either Hortonian or Dunnian runoff mechanisms. Ten thousand statistically consistent subsurface permeability fields are parameterized using a truncated Karhunen-Loéve (KL) series and used as inputs to 48-h simulations of integrated surface-subsurface flow in an idealized 'tilted-v' domain. Coefficients of the spatial modes of the KL permeability fields provide the parameter space for analysis using the active subspace method. The analysis shows that for Dunnian-dominated runoff conditions the cumulative runoff volume is sensitive primarily to the first spatial mode, corresponding to permeability values in the center of the three-dimensional model domain. In the Hortonian case, runoff volume is sensitive to multiple smaller-scale spatial modes and the locus of that sensitivity is in the near-surface zone upslope from the domain outlet. Variation in runoff volume resulting from random heterogeneity configurations can be expressed as an approximately univariate function of the active variable, a weighted combination of spatial parameterization coefficients computed through the active subspace method. However, this relationship between the active variable and runoff volume is more well-defined for Dunnian runoff than for the Hortonian scenario.

  20. The Virtual Tray of Objects Task as a novel method to electrophysiologically measure visuo-spatial recognition memory.

    PubMed

    Amico, Francesco; Ambrosini, Ettore; Guillem, François; Mento, Giovanni; Power, Dermot; Pergola, Giulio; Vallesi, Antonino

    2015-12-01

    We explored a novel method to electrophysiologically measure visuo-spatial recognition memory using a modified version of the Virtual Tray of Objects Task (VTOT). Event-related potentials (ERP) were recorded from 18 healthy volunteers during performance in the VTOT. Participants were required to detect random repetitions of three-dimensional visual stimuli (OLD) and to refrain from responding to non-repeated stimuli (NEW). Differences in ERP between the NEW and OLD conditions were tested for statistical significance using assumption-free non-parametric analyses. Further, a correlation between ERP and behavioral measures was sought. Significant OLD-NEW effects were found for four ERP components showing distinct spatio-temporal characteristics: a posterior positive component appearing at 100 ms (P100), a left-lateralized negative component peaking at ≈250 ms (N250), a frontal negative component at ≈300-450 ms (FN400), and a right late frontal negativity (rLFN) at ≈500-720 ms. Moreover, individual differences in the OLD-NEW effect computed for the rLFN positively correlated with repeated stimulus recognition efficiency. However, there were no late left parietal P600 old/new effects. These findings suggest that the P100 component might reflect early visual perception processes taking place during performance in the task, whereas the N250 and FN400 components could be linked to stimulus-dependent access to visual memory representations and familiarity-related processes, respectively. In contrast, we propose that the rLFN component could be associated with higher-level cognitive functions, such as attention and monitoring processes. Altogether, our results suggest that the ERP version of the VTOT could play a role in the electrophysiological assessment of visuo-spatial memory and related sub-processes. PMID:26546862

  1. Multilingual Access for Information Systems.

    ERIC Educational Resources Information Center

    Peters, Carol; Sheridan, Paraic

    With the rapid growth of the global information society, the concept of library has evolved to embrace all kinds of information collections, on all kinds of storage media, and using many different access methods. The users of today's information networks and digital libraries, no longer restricted by geographic or spatial boundaries, want to be…

  2. Switching methods in magnetic random access memory for low power applications

    NASA Astrophysics Data System (ADS)

    Guchang, Han; Jiancheng, Huang; Cheow Hin, Sim; Tran, Michael; Sze Ter, Lim

    2015-06-01

    Effect of saturation magnetization (Ms) of the free layer (FL) on the switching current is analyzed for spin transfer torque (STT) magnetic random access memory (MRAM). For in-plane FL, critical switching current (Ic0) decreases as Ms decreases. However, reduction in Ms also results in a low thermal stability factor (Δ), which must be compensated through increasing shape anisotropy, thus limiting scalability. For perpendicular FL, Ic0 reduction by using low-Ms materials is actually at the expense of data retention. To save energy consumed by STT current, two electric field (EF) controlled switching methods are proposed. Our simulation results show that elliptical FL can be switched by an EF pulse with a suitable width. However, it is difficult to implement this type of switching in real MRAM devices due to the distribution of the required switching pulse widths. A reliable switching method is to use an Oersted field guided switching. Our simulation and experimental results show that the bi-directional magnetization switching could be realized by an EF with an external field as low as  ±5 Oe if the offset field could be removed.

  3. A spectral nudging method for the ACCESS1.3 atmospheric model

    NASA Astrophysics Data System (ADS)

    Uhe, P.; Thatcher, M.

    2014-10-01

    A convolution based method of spectral nudging of atmospheric fields is developed in the Australian Community Climate and Earth Systems Simulator (ACCESS) version 1.3 which uses the UK Met Office Unified Model version 7.3 as its atmospheric component. The use of convolutions allow flexibility in application to different atmospheric grids. An approximation using one-dimensional convolutions is applied, improving the time taken by the nudging scheme by 10 to 30 times compared with a version using a two-dimensional convolution, without measurably degrading its performance. Care needs to be taken in the order of the convolutions and the frequency of nudging to obtain the best outcome. The spectral nudging scheme is benchmarked against a Newtonian relaxation method, nudging winds and air temperature towards ERA-Interim reanalyses. We find that the convolution approach can produce results that are competitive with Newtonian relaxation in both the effectiveness and efficiency of the scheme, while giving the added flexibility of choosing which length scales to nudge.

  4. A spectral nudging method for the ACCESS1.3 atmospheric model

    NASA Astrophysics Data System (ADS)

    Uhe, P.; Thatcher, M.

    2015-06-01

    A convolution-based method of spectral nudging of atmospheric fields is developed in the Australian Community Climate and Earth Systems Simulator (ACCESS) version 1.3 which uses the UK Met Office Unified Model version 7.3 as its atmospheric component. The use of convolutions allow for flexibility in application to different atmospheric grids. An approximation using one-dimensional convolutions is applied, improving the time taken by the nudging scheme by 10-30 times compared with a version using a two-dimensional convolution, without measurably degrading its performance. Care needs to be taken in the order of the convolutions and the frequency of nudging to obtain the best outcome. The spectral nudging scheme is benchmarked against a Newtonian relaxation method, nudging winds and air temperature towards ERA-Interim reanalyses. We find that the convolution approach can produce results that are competitive with Newtonian relaxation in both the effectiveness and efficiency of the scheme, while giving the added flexibility of choosing which length scales to nudge.

  5. Harmonic Spatial Coherence Imaging: An Ultrasonic Imaging Method Based on Backscatter Coherence

    PubMed Central

    Dahl, Jeremy J; Jakovljevic, Marko; Pinton, Gianmarco F.; Trahey, Gregg E.

    2012-01-01

    HSCI and SLSC imaging less sensitive to clutter because it has low spatial coherence. The method is based on the coherence of the second harmonic backscatter. Because the same signals that are used to construct harmonic B-mode images are also used to construct HSCI images, the benefits obtained with harmonic imaging are also applicable to HSCI. Harmonic imaging has been the primary tool for suppressing clutter in diagnostic ultrasound imaging, however second harmonic echoes are not necessarily immune to the effects of clutter. HSCI and SLSC imaging are less sensitive to clutter because it has low spatial coherence. Harmonic Spatial Coherence Imaging shows favorable imaging characteristics such as improved contrast-to-noise ratio (CNR), improved speckle signal-to-noise ratio (SNR), and better delineation of borders and other structures compared to fundamental and harmonic B-mode imaging. CNRs of up to 1.9 were obtained from in vivo imaging of human cardiac tissue with HSCI, compared to 0.6, 0.9, and 1.5 in fundamental B-mode, harmonic B-mode, and SLSC imaging, respectively. In vivo experiments in human liver tissue demonstrated SNRs of up to 3.4 for HSCI compared to 1.9 for harmonic B-mode. Nonlinear simulations of a heart chamber model were consistent with the in vivo experiments. PMID:22547276

  6. Analysis of spatial and temporal water pollution patterns in Lake Dianchi using multivariate statistical methods.

    PubMed

    Yang, Yong-Hui; Zhou, Feng; Guo, Huai-Cheng; Sheng, Hu; Liu, Hui; Dao, Xu; He, Cheng-Jie

    2010-11-01

    Various multivariate statistical methods including cluster analysis (CA), discriminant analysis (DA), factor analysis (FA), and principal component analysis (PCA) were used to explain the spatial and temporal patterns of surface water pollution in Lake Dianchi. The dataset, obtained during the period 2003-2007 from the Kunming Environmental Monitoring Center, consisted of 12 variables surveyed monthly at eight sites. The CA grouped the 12 months into two groups, August-September and the remainder, and divided the lake into two regions based on their different physicochemical properties and pollution levels. The DA showed the best results for data reduction and pattern recognition in both temporal and spatial analysis. It calculated four parameters (TEMP, pH, CODMn, and Chl-a) to 85.4% correct assignment in the temporal analysis and three parameters (BOD, NH₄+-N, and TN) to almost 71.7% correct assignment in spatial analysis of the two clusters. The FA/PCA applied to datasets of two special clusters of the lake calculated four factors for each region, capturing 72.5% and 62.5% of the total variance, respectively. Strong loadings included DO, BOD, TN, CODCr, CODMn, NH₄+-N, TP, and EC. In addition, box-whisker plots and GIS further facilitated and supported the multivariate analysis results. PMID:19936953

  7. A Comparison of Spatial Analysis Methods for the Construction of Topographic Maps of Retinal Cell Density

    PubMed Central

    Garza-Gisholt, Eduardo; Hemmi, Jan M.; Hart, Nathan S.; Collin, Shaun P.

    2014-01-01

    Topographic maps that illustrate variations in the density of different neuronal sub-types across the retina are valuable tools for understanding the adaptive significance of retinal specialisations in different species of vertebrates. To date, such maps have been created from raw count data that have been subjected to only limited analysis (linear interpolation) and, in many cases, have been presented as iso-density contour maps with contour lines that have been smoothed ‘by eye’. With the use of stereological approach to count neuronal distribution, a more rigorous approach to analysing the count data is warranted and potentially provides a more accurate representation of the neuron distribution pattern. Moreover, a formal spatial analysis of retinal topography permits a more robust comparison of topographic maps within and between species. In this paper, we present a new R-script for analysing the topography of retinal neurons and compare methods of interpolating and smoothing count data for the construction of topographic maps. We compare four methods for spatial analysis of cell count data: Akima interpolation, thin plate spline interpolation, thin plate spline smoothing and Gaussian kernel smoothing. The use of interpolation ‘respects’ the observed data and simply calculates the intermediate values required to create iso-density contour maps. Interpolation preserves more of the data but, consequently includes outliers, sampling errors and/or other experimental artefacts. In contrast, smoothing the data reduces the ‘noise’ caused by artefacts and permits a clearer representation of the dominant, ‘real’ distribution. This is particularly useful where cell density gradients are shallow and small variations in local density may dramatically influence the perceived spatial pattern of neuronal topography. The thin plate spline and the Gaussian kernel methods both produce similar retinal topography maps but the smoothing parameters used may affect

  8. A New Method of Assessing the Extent of Topographic Equilibrium at Different Spatial Scales

    NASA Astrophysics Data System (ADS)

    Walcott, R.

    2013-12-01

    The Earth's surface represents the current resultant state of the interaction between forces working to lower topography and those working to resist this, or to raise topography. A diversity of processes generate these forces and in some cases coupled feedbacks allow a dynamic equilibrium to emerge at certain spatial and temporal scales. Dynamic equilibrium is typically expressed by distinctive geometries (e.g., regular catchment shapes, first order geometry of an orogen, constant thickness of a soil horizon over space). However, the presence of stochastic surface and tectonic processes also means that regular geometries are rarely observed at all scales. Determining the scale and temporal range over which topography can be considered to be in equilibrium can be difficult and expensive, requiring a large range of spatially distributed data, and/or data that spans significant time periods. Here we present a new morphometric method that focuses on the product of erosive competition between catchments, that is the geometry of drainage divide intersections. We use this method to show that stable areas, with minimal tectonic disturbance and homogeneous rock types have distinctive drainage divide geometry (e.g. Eastern USA) which differs from the geometry of drainage divide intersections in other environments (e.g. tectonically active regions such as the South Island of New Zealand). With a few caveats, this method could be used to predict areas prone to drainage divide migration and river network reconfiguration.

  9. Over-constraint and a unified mobility method for general spatial mechanisms part 1: Essential principle

    NASA Astrophysics Data System (ADS)

    Zeng, Daxing; Lu, Wenjuan; Huang, Zhen

    2015-09-01

    Compared with the parallel mechanisms, the mobility analysis of the general multi-loop spatial mechanisms(GMSMs) is more difficult to obtain correct results. The reason is that its multi-loop is formed through several times of closings and there also exists motion coupling even strong coupling, where the over-constraints are concealed. However, the mobility analysis for this kind of mechanisms has been paid few attentions. A new systemic methodology for analyzing mobility is proposed for GMSMs also based on the screw theory. The key issue for mobility analysis is to recognize the over-constraint. Firstly, three theorems are given and point out: the reason and site of over-constraint occurrence, calculating the number of over-constraints by the screw theory, and how to analyze the over-constraints for a single-loop mechanism as well. Then, three closing forms for GMSMs are proposed including rigid closure, movable closure and dynamic closure, and for the three different forms the different analysis methods are also given. Especially, for the most difficult issue of GMSMs with the multi-loop closure in many times and the inevitable motion coupling, two important methods are proposed: "recognizing over-constraints by analyzing relative movement" and "recognizing over-constraints by virtual loop". The two methods are well used to solve the issue. Above-mentioned principles are not only systematic and effective but also unified. They provide a theoretical basis for the general multi-loop spatial mechanisms.

  10. Methods and spatial extent of geophysical Investigations, Mono Lake, California, 2009 to 2011

    USGS Publications Warehouse

    Jayko, A.S.; Hart, P.E.; Childs, J. R.; Cormier, M.-H.; Ponce, D.A.; Athens, N.D.; McClain, J.S.

    2013-01-01

    This report summarizes the methods and spatial extent of geophysical surveys conducted on Mono Lake and Paoha Island by U.S. Geological Survey during 2009 and 2011. The surveys include acquisition of new high resolution seismic reflection data, shipborne high resolution magnetic data, and ground magnetic and gravity data on Paoha Island. Several trials to acquire swath bathymetry and side scan sonar were conducted, but were largely unsuccessful likely due to physical properties of the water column and (or) physical properites of the highly organic bottom sediment.

  11. High order finite difference and multigrid methods for spatially evolving instability in a planar channel

    NASA Technical Reports Server (NTRS)

    Liu, C.; Liu, Z.

    1993-01-01

    The fourth-order finite-difference scheme with fully implicit time-marching presently used to computationally study the spatial instability of planar Poiseuille flow incorporates a novel treatment for outflow boundary conditions that renders the buffer area as short as one wavelength. A semicoarsening multigrid method accelerates convergence for the implicit scheme at each time step; a line-distributive relaxation is developed as a robust fast solver that is efficient for anisotropic grids. Computational cost is no greater than that of explicit schemes, and excellent agreement with linear theory is obtained.

  12. The panel-clustering method for the wave equation in two spatial dimensions

    NASA Astrophysics Data System (ADS)

    Falletta, Silvia; Sauter, Stefan A.

    2016-01-01

    We consider the numerical solution of the wave equation in a two-dimensional domain and start from a boundary integral formulation for its discretization. We employ the convolution quadrature (CQ) for the temporal and a Galerkin boundary element method (BEM) for the spatial discretization. Our main focus is the sparse approximation of the arising sequence of boundary integral operators by panel clustering. This requires the definition of an appropriate admissibility condition such that the arising kernel functions can be efficiently approximated on admissible blocks. The resulting method has a complexity of O (N (N + M) q 4 + s) , s ∈ { 0 , 1 } , where N is the number of time points, M denotes the dimension of the boundary element space, and q = O (log ⁡ (NM)) is the order of the panel-clustering expansion. Numerical experiments will illustrate the efficiency and accuracy of the proposed CQ-BEM method with panel clustering.

  13. Spatial resolution of the electrical conductance of ionic fluids using a Green-Kubo method.

    PubMed

    Jones, R E; Ward, D K; Templeton, J A

    2014-11-14

    We present a Green-Kubo method to spatially resolve transport coefficients in compositionally heterogeneous mixtures. We develop the underlying theory based on well-known results from mixture theory, Irving-Kirkwood field estimation, and linear response theory. Then, using standard molecular dynamics techniques, we apply the methodology to representative systems. With a homogeneous salt water system, where the expectation of the distribution of conductivity is clear, we demonstrate the sensitivities of the method to system size, and other physical and algorithmic parameters. Then we present a simple model of an electrochemical double layer where we explore the resolution limit of the method. In this system, we observe significant anisotropy in the wall-normal vs. transverse ionic conductances, as well as near wall effects. Finally, we discuss extensions and applications to more realistic systems such as batteries where detailed understanding of the transport properties in the vicinity of the electrodes is of technological importance. PMID:25399135

  14. Video quality assessment using content-weighted spatial and temporal pooling method

    NASA Astrophysics Data System (ADS)

    Li, Chaofeng; Pan, Feng; Wu, Xiaojun; Ju, Yiwen; Yuan, Yun-Hao; Fang, Wei

    2015-09-01

    Video quality assessment plays an important role in video processing and communication applications. We propose a full reference video quality metric by combining a content-weighted spatial pooling strategy with a temporal pooling strategy. All pixels in a frame are classified into edge, texture, and smooth regions, and their structural similarity image index (SSIM) maps are divided into increasing and saturated regions by the curve of their SSIM values, then a content weight method is applied to increasing regions to get the score of an image frame. Finally, a temporal pooling method is used to get the overall video quality. Experimental results on the LIVE and IVP video quality databases show our proposed method works well in matching subjective scores.

  15. Topological investigation of glucosyltransferase V in Shigella flexneri using the substituted cysteine accessibility method.

    PubMed

    Rusden, Anthony D; Stephenson, David P; Verma, Naresh K

    2013-04-16

    Modification of the lipopolysaccharide O-antigen of Shigella converts the serotype, which is significant as acquired immune responses are serotype specific. Glucosyltransferases (Gtrs) modify the O-antigen by the addition of glucosyl-groups; however the precise mechanism of O-antigen modification is not fully understood. This study aims to substantiate inferences made on the GtrV topological structure using the substituted cysteine accessibility method (SCAM). Twenty-one amino acid residues were tested to clarify three features of GtrV: the extramembrane regions, a proposed reentrant loop, and a membrane border region. Overall, the results agreed with a previous topology proposed for GtrV. The topology of GtrV consists of 11 extramembrane regions with a cytoplasmic N-terminus, periplasmic C-terminus and 9 transmembrane (TM) helices. The existence of a reentrant loop between TM helices IV and V was verified, and the cytoplasmic membrane border region of TM helix II was examined in depth. PMID:23534399

  16. An advanced image processing method to improve the spatial resolution of ion radiographies.

    PubMed

    Krah, N; Testa, M; Brons, S; Jäkel, O; Parodi, K; Voss, B; Rinaldi, I

    2015-11-01

    We present an optimization method to improve the spatial resolution and the water equivalent thickness (WET) accuracy of ion radiographies. The method is designed for imaging systems measuring for each actively scanned beam spot the lateral position of the pencil beam and at the same time the Bragg curve (behind the target) in discrete steps without relying on tracker detectors to determine the ion trajectory before and after the irradiated volume. Specifically, the method was used for an imaging set-up consisting of a stack of 61 parallel-plate ionization chambers (PPIC) interleaved with absorber plates of polymethyl methacrylate (PMMA) working as a range telescope. The method uses not only the Bragg peak position, but approximates the entire measured Bragg curve as a superposition of differently shifted Bragg curves. Their relative weights allow to reconstruct the distribution of thickness around each scan spot of a heterogeneous phantom. The approach also allows merging the ion radiography with the geometric information of a co-registered x-ray radiography in order to increase its spatial resolution. The method was tested using Monte Carlo simulated and experimental proton radiographies of a PMMA step phantom and an anthropomorphic head phantom. For the step phantom, the effective spatial resolution was found to be 6 and 4 times higher than the nominal resolution for the simulated and experimental radiographies, respectively. For the head phantom, a gamma index was calculated to quantify the conformity of the simulated proton radiographies with a digitally reconstructed radiography (DRR) obtained from an x-ray CT and properly converted into WET. For a distance-to-agreement (DTA) of 2.5 mm and a relative WET difference (RWET) of 2.5%, the passing ratio was 100%/85% for the optimized/non-optimized case, respectively. When the optimized proton radiography was merged with the co-registered DRR, the passing ratio was 100% at DTA  =  1.3 mm and RWET

  17. An advanced image processing method to improve the spatial resolution of ion radiographies

    NASA Astrophysics Data System (ADS)

    Krah, N.; Testa, M.; Brons, S.; Jäkel, O.; Parodi, K.; Voss, B.; Rinaldi, I.

    2015-11-01

    We present an optimization method to improve the spatial resolution and the water equivalent thickness (WET) accuracy of ion radiographies. The method is designed for imaging systems measuring for each actively scanned beam spot the lateral position of the pencil beam and at the same time the Bragg curve (behind the target) in discrete steps without relying on tracker detectors to determine the ion trajectory before and after the irradiated volume. Specifically, the method was used for an imaging set-up consisting of a stack of 61 parallel-plate ionization chambers (PPIC) interleaved with absorber plates of polymethyl methacrylate (PMMA) working as a range telescope. The method uses not only the Bragg peak position, but approximates the entire measured Bragg curve as a superposition of differently shifted Bragg curves. Their relative weights allow to reconstruct the distribution of thickness around each scan spot of a heterogeneous phantom. The approach also allows merging the ion radiography with the geometric information of a co-registered x-ray radiography in order to increase its spatial resolution. The method was tested using Monte Carlo simulated and experimental proton radiographies of a PMMA step phantom and an anthropomorphic head phantom. For the step phantom, the effective spatial resolution was found to be 6 and 4 times higher than the nominal resolution for the simulated and experimental radiographies, respectively. For the head phantom, a gamma index was calculated to quantify the conformity of the simulated proton radiographies with a digitally reconstructed radiography (DRR) obtained from an x-ray CT and properly converted into WET. For a distance-to-agreement (DTA) of 2.5 mm and a relative WET difference (RWET) of 2.5%, the passing ratio was 100%/85% for the optimized/non-optimized case, respectively. When the optimized proton radiography was merged with the co-registered DRR, the passing ratio was 100% at DTA  =  1.3 mm and RWET

  18. Joint Variable Spatial Downscaling (JVSD): A New Downscaling Method with Application to the Southeast US

    NASA Astrophysics Data System (ADS)

    Zhang, F.; Georgakakos, A. P.

    2011-12-01

    Joint Variable Spatial Downscaling (JVSD) is a new downscaling method developed to produce high resolution gridded hydrological datasets suitable for regional watershed modeling and assessments. JVSD differs from other statistical downscaling methods in that multiple climatic variables are downscaled simultaneously to produce realistic and consistent climate fields. JVSD includes two major steps: bias correction and spatial downscaling. In the bias correction step, JVSD uses a differencing process to create stationary joint cumulative frequency statistics of the variables being downscaled. Bias correction is then based on quantile-to-quantile mapping of these stationary frequency distributions probability space. The functional relationship between these statistics and those of the historical observation period is subsequently used to remove GCM bias. The original variables are recovered through summation of bias corrected differenced sequences. In the spatial disaggregation step, JVSD uses a historical analogue approach, with historical analogues identified simultaneously for all atmospheric fields and over all areas of the basin under study. Analysis and comparisons with 20th Century Climate in Coupled Models (20C3M) data show that JVSD reproduces the sub-grid climatic features as well as their temporal/spatial variability in the historical periods. Comparisons are also performed for precipitation and temperature with the North American regional climate change assessment program (NARCCAP) and other statistical downscaling methods over the southeastern US. The results show that JVSD performs favorably. JVSD is applied for all A1B and A2 CMIP3 GCM scenarios in the Apalachicola-Chattahoochee-Flint River Basin (southeast US) with the following general findings: (i) Mean monthly temperature exhibits increasing trends over the ACF basin for all seasons and all A1B and A2 scenarios; Most significant are the A2 temperature increases in the 2050 - 2099 time periods; (ii

  19. 3D micro profile measurement with the method of spatial frequency domain analysis

    NASA Astrophysics Data System (ADS)

    Xu, Yongxiang

    2015-10-01

    3D micro profiles are often needed for measurement in many fields, e.g., binary optics, electronic industry, mechanical manufacturing, aeronautic and space industry, etc. In the case where height difference between two neighboring points of a test profile is equal to or greater than λ / 4, microscopic interferometry based on laser source will no longer be applicable because of the uncertainty in phase unwrapping. As white light possesses the characteristic of interference length approximate to zero, applying it for micro profilometry can avoid the trouble and can yield accurate results. Using self-developed Mirau-type scanning interference microscope, a step-like sample was tested twice, with 128 scanning interferograms recorded for each test. To process each set of the interferograms, the method of spatial frequency domain analysis was adopted. That is, for each point, by use of Furrier transform, white-light interference intensities were decomposed in spatial frequency domain, thus obtaining phase values corresponding to different wavenumbers; by using least square fitting on phases and wave numbers, a group-velocity OPD was gained for the very point; and finally in terms of the relation between relative height and the group-velocity OPD, the profile of the test sample was obtained. Two tests yielded same profile result for the sample, and step heights obtained were 50.88 nm and 50.94 nm, respectively. Meantime, the sample was also measured with a Zygo Newview 7200 topography instrument, with same profile result obtained and step height differing by 0.9 nm. In addition, data processing results indicate that chromatic dispersion equal to and higher than 2nd order is negligible when applying spatial frequency domain analysis method.

  20. A comparison of magnetic resonance methods for spatially resolved T2 distribution measurements in porous media

    NASA Astrophysics Data System (ADS)

    Vashaee, S.; Marica, F.; Newling, B.; Balcom, B. J.

    2015-05-01

    Naturally occurring porous media are usually characterized by a distribution of pore sizes. If the material is fluid saturated, the 1H magnetic resonance (MR) signal depends on the pore size, the surface relaxivity and the fluid itself. Measurement of the transverse relaxation time T2 is a well-established technique to characterize material samples by means of MR. T2 distribution measurements, including T2 distribution mapping, are widely employed in clinical applications and in petroleum engineering. T2 distribution measurements are the most basic measurement employed to determine the fluid-matrix properties in MR core analysis. Three methods for T2 distribution mapping, namely spin-echo single point imaging (SE-SPI), DANTE-Z Carr-Purcell-Meiboom-Gill (CPMG) and adiabatic inversion CPMG are compared in terms of spatial resolution, minimum observable T2 and sensitivity. Bulk CPMG measurement is considered to be the gold standard for T2 determination. Bulk measurement of uniform samples is compared to the three spatially resolved measurements. SE-SPI is an imaging method, which measures spatially resolved T2s in samples of interest. A variant is introduced in this work that employs pre-equalized magnetic field gradient waveforms and is therefore able to measure shorter T2s than previously reported. DANTE-Z CPMG and adiabatic inversion CPMG are faster, non-imaging, local T2 distribution measurements. The DANTE-Z pulse train and adiabatic inversion pulse are compared in terms of T1 or T2 relaxation time effects during the RF pulse application, minimum pulse duration, requisite RF pulse power, and inversion profile quality. In addition to experimental comparisons, simulation results are presented.

  1. An Improved Multi-Temporal Insar Method for Increasing Spatial Resolution of Surface Deformation Measurements

    NASA Astrophysics Data System (ADS)

    Li, T.; Liu, G.; Jia, H.; Lin, H.; Zhang, R.; Yu, B.; Luo, Q.

    2013-10-01

    The multi-temporal interferometric synthetic aperture radar (InSAR) technology has proven very useful in extracting surface deformation with time series of SAR images over a study area. To increase spatial resolution of deformation information, this paper presents an improved multi-temporal InSAR (MTI) method by tracking both the point-like targets (PTs) and the distributed targets (DTs) with temporal steadiness of radar backscattering. The valid pixels corresponding to PTs and DTs are identified mainly by thresholding of the amplitude dispersion index (ADI) and the Pearson correlation coefficient (PCC). To efficiently reduce error propagation, a hierarchical analysis strategy is applied to extract deformation rates at the valid pixels. For the pixels with lower ADI values, the deformation rates are estimated on an optimized network by a least squared estimator and a region growing method. For the pixels with higher ADI values, they are classified into several groups by the ADI intervals, and the deformation rates are estimated through the multi-levels of processing. The nonlinear deformation values at all the valid pixels are estimated by spatiotemporally filtering and spatially integrating. The proposed MTI algorithm has been tested for subsidence detection over Tianjin in China using the 40 high resolution TerraSAR-X images acquired between 2009 and 2010, and validated by using the ground-based leveling measurements. The testing results indicate that the spatial resolution and coverage of subsidence data can be increased dramatically by the hierarchical analysis, and the accuracy in subsidence values derived from the MTI solution can reach up to a millimeter level.

  2. Extension of the spatial autocorrelation (SPAC) method to mixed-component correlations of surface waves

    USGS Publications Warehouse

    Haney, Matthew M.; Mikesell, T. Dylan; van Wijk, Kasper; Nakahara, Hisashi

    2012-01-01

    Using ambient seismic noise for imaging subsurface structure dates back to the development of the spatial autocorrelation (SPAC) method in the 1950s. We present a theoretical analysis of the SPAC method for multicomponent recordings of surface waves to determine the complete 3 × 3 matrix of correlations between all pairs of three-component motions, called the correlation matrix. In the case of isotropic incidence, when either Rayleigh or Love waves arrive from all directions with equal power, the only non-zero off-diagonal terms in the matrix are the vertical–radial (ZR) and radial–vertical (RZ) correlations in the presence of Rayleigh waves. Such combinations were not considered in the development of the SPAC method. The method originally addressed the vertical–vertical (ZZ), RR and TT correlations, hence the name spatial autocorrelation. The theoretical expressions we derive for the ZR and RZ correlations offer additional ways to measure Rayleigh wave dispersion within the SPAC framework. Expanding on the results for isotropic incidence, we derive the complete correlation matrix in the case of generally anisotropic incidence. We show that the ZR and RZ correlations have advantageous properties in the presence of an out-of-plane directional wavefield compared to ZZ and RR correlations. We apply the results for mixed-component correlations to a data set from Akutan Volcano, Alaska and find consistent estimates of Rayleigh wave phase velocity from ZR compared to ZZ correlations. This work together with the recently discovered connections between the SPAC method and time-domain correlations of ambient noise provide further insights into the retrieval of surface wave Green’s functions from seismic noise.

  3. Methods and apparatus for integrating, organizing, and accessing flight planning and other data on multifunction cockpit displays

    NASA Technical Reports Server (NTRS)

    Gibbs, Michael J. (Inventor); Van Omen, Debi (Inventor); Adams, Michael B. (Inventor); Chase, Karl L. (Inventor); Lewis, Daniel E. (Inventor); McCrobie, Daniel E. (Inventor)

    2003-01-01

    A method and system for displaying a flight plan such that an entire flight plan is viewable through the use of scrolling devices is disclosed. The flight plan display may also include a method and system for collapsing and expanding a flight plan display, have provisions for the conspicuous marking of changes to a flight plan, the use of tabs to switch between various displays of data, and access to a navigation database that allows a user to view information about various navigational aids. The database may also the access to the information about the navigational aids to be prioritized based on proximity to the current position of the aircraft.

  4. A combined spatial-spectral method for automated white blood cells segmentation

    NASA Astrophysics Data System (ADS)

    Li, Qingli; Wang, Yiting; Liu, Hongying; Wang, Jianbiao; Guo, Fangmin

    2013-12-01

    To overcome the shortcomings in the traditional white blood cells (WBCs) identification methods based on the color or gray images captured by light microscopy, a microscopy hyperspectral imaging system was used to analyze the blood smears. The system was developed by coupling an acousto-optic tunable filter (AOTF) adapter to a microscopy and driven by a SPF Model AOTF controller, which can capture hyperspectral images from 550 nm to 1000 nm with the spectral resolution 2-5 nm. Moreover, a combined spatial-spectral algorithm is proposed to segment the nuclei and cytoplasm of WBCs from the microscopy hyperspectral images. The proposed algorithm is based on the pixel-wise improved spectral angle mapper (ISAM) segmentation, followed by the majority voting within the active contour model regions. Experimental results show that the accuracy of the proposed algorithm is 91.06% (nuclei) and 85.59% (cytoplasm), respectively, which is higher than that of the spectral information divergence (SID) algorithm because the new method can jointly use both the spectral and spatial information of blood cells.

  5. A method of generating atmospheric turbulence with a liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Wilcox, Christopher C.; Santiago, Freddie; Martinez, Ty; Andrews, Jonathan R.; Restaino, Sergio R.; Corley, Melissa; Teare, Scott W.; Agrawal, Brij N.

    2010-08-01

    The Naval Research Laboratory has developed a new method for generating atmospheric turbulence and a testbed that simulates its aberrations far more inexpensively and with greater fidelity using a Liquid Crystal (LC) Spatial Light Modulator (SLM) than many other methods. This system allows the simulation of atmospheric seeing conditions ranging from very poor to very good and different algorithms may be easily employed on the device for comparison. These simulations can be dynamically generated and modified very quickly and easily. In addition, many models for simulating turbulence often neglect temporal transitions along with different seeing conditions. Using the statistically independent set of Karhunen-Loeve polynomials in conjunction with Kolmogorov statistics in this model provides an accurate spatial and temporal model for simulating turbulence. An added benefit to using a LC SLM is its low cost; and multiple devices can be used to simulate multiple layers of turbulence in a laboratory environment. Current testing with using multiple LC SLMs is under investigation at the Naval Research Laboratory and the Naval Postgraduate School.

  6. Different spatial discretization methods of fault systems on heat transport processes in hard rock aquifers

    NASA Astrophysics Data System (ADS)

    Kruppa, Lisa; König, Christoph M.; Becker, Martin; Seidel, Torsten

    2016-04-01

    Most hard rock aquifers, which are important for geothermal use, contain fractures of different type and scale. These fault systems are of major significance for heat flow in the groundwater. The hydrogeological characterization of fault systems must therefore be part of any site investigation in hard rock aquifers and hydraulically important fault systems need to be appropriately represented in associated numerical models. This contribution discusses different spatial discretization methods of fault systems in three-dimensional groundwater models and their impact on the simulated groundwater flow field as well as density and viscosity dependent heat transport. The analysis includes a comparison of the convergence behavior and numerical stability of the different discretization methods. To ensure defendable results, the utilized numerical model SPRING was first verified against data from the Hydrocoin Level 1 Case 2 project. After verification, the software was used to evaluate the impact of different discretization strategies on steady-state and transient groundwater flow and transport model results. The results show a significant influence of the spatial discretization strategy on predicted flow rates and subsequent mass fluxes as well as energy balances.

  7. Study on mosaic method for new mode satellite images with high spatial resolution covering urban areas

    NASA Astrophysics Data System (ADS)

    Ran, Qiong; Wang, Zhiyong; Wen, Qiang; Li, Wei; Gao, Lianru

    2014-11-01

    New imaging mode has been brought up for collecting multiple scenes in one pass, as is implemented on World View-II. This greatly helps for acquiring high spatial resolution images that cover urban areas, and is to be adopted in the coming Chinese satellites. This paper is to discuss the mosaic characteristic and propose a mosaic line generation method by integrating correlation and the road information. The mosaic line is formed by linking the unique mosaic point on each line restricted within the road. We position the starting point by connectivity analysis of the road lines, and then locate the adjacent point along the road with connectivity analysis. A weighed vector, combining correlation and distance to centre of the road, is used to pick the best point. The points are located on the road unless it is unavoidable, for example, the road ends or the line touches edge of the image. This method provides instant mosaic line generation for urban areas with road information available in most cases. By resorting to the road, the mosaic line is more applicable since many problems for mosaic of high spatial resolution images are solved, for example, tilting of the buildings, the shadows, motions of the vehicles etc. Experiments have been done with WV-II images and gained favorable results.

  8. New image analysis method for the estimation of global and spatial changes in fruit microstructure

    NASA Astrophysics Data System (ADS)

    Pieczywek, Piotr M.; Cybulska, Justyna; Dyki, Barbara; Konopacka, Dorota; Mieszczakowska-Frąc, Monika; Zdunek, Artur

    2016-04-01

    A new image analysis method for the spatial characterization of microscopy images of fruit microstructure is proposed in order to analyse the heterogeneous microstructure of unprocessed fruit and the possible inhomogeneous effects of various technological treatments on this microstructure. The micro-structure of tissue samples was characterized using the global statistics of size and shape parameters calculated for all visible objects. Global analysis was supported by a novel algorithm that allowed for drawing of the maps of the cell wall fraction from microscopy images and for the analysis of both global and local compaction or loosening of tissue. The spatial distribution of the cell wall fraction was visualised in the convenient form of bivariate histograms. To test the developed image analysis protocols, structural changes resulting from ultrasonic and osmotic treatments of apple tissue samples were studied. Peeled and cored apples were submersed in a liquid medium (distilled water or 60 °Bx sucrose solution) for 45 and 90 min with and without ultrasonic treatment. After these treatment procedures, tissue samples were cut into slices, stained and imaged using a microscope. The proposed method allowed to characterise the effects of different sample treatments.

  9. a Kernel Method Based on Topic Model for Very High Spatial Resolution (vhsr) Remote Sensing Image Classification

    NASA Astrophysics Data System (ADS)

    Wu, Linmei; Shen, Li; Li, Zhipeng

    2016-06-01

    A kernel-based method for very high spatial resolution remote sensing image classification is proposed in this article. The new kernel method is based on spectral-spatial information and structure information as well, which is acquired from topic model, Latent Dirichlet Allocation model. The final kernel function is defined as K = u1Kspec + u2Kspat + u3Kstru, in which Kspec, Kspat, Kstru are radial basis function (RBF) and u1 + u2 + u3 = 1. In the experiment, comparison with three other kernel methods, including the spectral-based, the spectral- and spatial-based and the spectral- and structure-based method, is provided for a panchromatic QuickBird image of a suburban area with a size of 900 × 900 pixels and spatial resolution of 0.6 m. The result shows that the overall accuracy of the spectral- and structure-based kernel method is 80 %, which is higher than the spectral-based kernel method, as well as the spectral- and spatial-based which accuracy respectively is 67 % and 74 %. What's more, the accuracy of the proposed composite kernel method that jointly uses the spectral, spatial, and structure information is highest among the four methods which is increased to 83 %. On the other hand, the result of the experiment also verifies the validity of the expression of structure information about the remote sensing image.

  10. A Real-Time Infrared Ultra-Spectral Signature Classification Method via Spatial Pyramid Matching

    PubMed Central

    Mei, Xiaoguang; Ma, Yong; Li, Chang; Fan, Fan; Huang, Jun; Ma, Jiayi

    2015-01-01

    The state-of-the-art ultra-spectral sensor technology brings new hope for high precision applications due to its high spectral resolution. However, it also comes with new challenges, such as the high data dimension and noise problems. In this paper, we propose a real-time method for infrared ultra-spectral signature classification via spatial pyramid matching (SPM), which includes two aspects. First, we introduce an infrared ultra-spectral signature similarity measure method via SPM, which is the foundation of the matching-based classification method. Second, we propose the classification method with reference spectral libraries, which utilizes the SPM-based similarity for the real-time infrared ultra-spectral signature classification with robustness performance. Specifically, instead of matching with each spectrum in the spectral library, our method is based on feature matching, which includes a feature library-generating phase. We calculate the SPM-based similarity between the feature of the spectrum and that of each spectrum of the reference feature library, then take the class index of the corresponding spectrum having the maximum similarity as the final result. Experimental comparisons on two publicly-available datasets demonstrate that the proposed method effectively improves the real-time classification performance and robustness to noise. PMID:26205263

  11. A Real-Time Infrared Ultra-Spectral Signature Classification Method via Spatial Pyramid Matching.

    PubMed

    Mei, Xiaoguang; Ma, Yong; Li, Chang; Fan, Fan; Huang, Jun; Ma, Jiayi

    2015-01-01

    The state-of-the-art ultra-spectral sensor technology brings new hope for high precision applications due to its high spectral resolution. However, it also comes with new challenges, such as the high data dimension and noise problems. In this paper, we propose a real-time method for infrared ultra-spectral signature classification via spatial pyramid matching (SPM), which includes two aspects. First, we introduce an infrared ultra-spectral signature similarity measure method via SPM, which is the foundation of the matching-based classification method. Second, we propose the classification method with reference spectral libraries, which utilizes the SPM-based similarity for the real-time infrared ultra-spectral signature classification with robustness performance. Specifically, instead of matching with each spectrum in the spectral library, our method is based on feature matching, which includes a feature library-generating phase. We calculate the SPM-based similarity between the feature of the spectrum and that of each spectrum of the reference feature library, then take the class index of the corresponding spectrum having the maximum similarity as the final result. Experimental comparisons on two publicly-available datasets demonstrate that the proposed method effectively improves the real-time classification performance and robustness to noise. PMID:26205263

  12. Spatial Pattern of Great Lakes Estuary Processes from Water Quality Sensing and Geostatistical Methods

    NASA Astrophysics Data System (ADS)

    Xu, W.; Minsker, B. S.; Bailey, B.; Collingsworth, P.

    2014-12-01

    Mixing of river and lake water can alter water temperature, conductivity, and other properties that influence ecological processes in freshwater estuaries of the Great Lakes. This study uses geostatistical methods to rapidly visualize and understand water quality sampling results and enable adaptive sampling to remove anomalies and explore interesting phenomena in more detail. Triaxus, a towed undulating sensor package, was used for collecting various physical and biological water qualities in three estuary areas of Lake Michigan in Summer 2011. Based on the particular sampling pattern, data quality assurance and quality control (QA/QC) processes, including sensor synchronization, upcast and downcast separation, and spatial outlier removal are first applied. An automated kriging interpolation approach that considers trend and anisotropy is then proposed to estimate data on a gridded map for direct visualization. Other methods are explored with the data to gain more insights on water quality processes. Local G statistics serve as a supplementary tool to direct visualization. The method identifies statistically high value zones (hot spots) and low value zones (cold spots) in water chemistry across the estuaries, including locations of water sources and intrusions. In addition, chlorophyll concentration distributions are different among sites. To further understand the interactions and differences between river and lake water, K-means clustering algorithm is used to spatially cluster the water based on temperature and specific conductivity. Statistical analysis indicates that clusters with significant river water can be identified from higher turbidity, specific conductivity, and chlorophyll concentrations. Different ratios between zooplankton biomass and density indicate different zooplankton structure across clusters. All of these methods can contribute to improved near real-time analysis of future sampling activity.

  13. A new method for estimating carbon dioxide emissions from transportation at fine spatial scales

    NASA Astrophysics Data System (ADS)

    Shu, Yuqin; Lam, Nina S. N.; Reams, Margaret

    2010-10-01

    Detailed estimates of carbon dioxide (CO2) emissions at fine spatial scales are useful to both modelers and decision makers who are faced with the problem of global warming and climate change. Globally, transport related emissions of carbon dioxide are growing. This letter presents a new method based on the volume-preserving principle in the areal interpolation literature to disaggregate transportation-related CO2 emission estimates from the county-level scale to a 1 km2 grid scale. The proposed volume-preserving interpolation (VPI) method, together with the distance-decay principle, were used to derive emission weights for each grid based on its proximity to highways, roads, railroads, waterways, and airports. The total CO2 emission value summed from the grids within a county is made to be equal to the original county-level estimate, thus enforcing the volume-preserving property. The method was applied to downscale the transportation-related CO2 emission values by county (i.e. parish) for the state of Louisiana into 1 km2 grids. The results reveal a more realistic spatial pattern of CO2 emission from transportation, which can be used to identify the emission 'hot spots'. Of the four highest transportation-related CO2 emission hotspots in Louisiana, high-emission grids literally covered the entire East Baton Rouge Parish and Orleans Parish, whereas CO2 emission in Jefferson Parish (New Orleans suburb) and Caddo Parish (city of Shreveport) were more unevenly distributed. We argue that the new method is sound in principle, flexible in practice, and the resultant estimates are more accurate than previous gridding approaches.

  14. A new method for estimating carbon dioxide emissions from transportation at fine spatial scales

    PubMed Central

    Shu, Yuqin; Reams, Margaret

    2016-01-01

    Detailed estimates of carbon dioxide (CO2) emissions at fine spatial scales are useful to both modelers and decision makers who are faced with the problem of global warming and climate change. Globally, transport related emissions of carbon dioxide are growing. This letter presents a new method based on the volume-preserving principle in the areal interpolation literature to disaggregate transportation-related CO2 emission estimates from the county-level scale to a 1 km2 grid scale. The proposed volume-preserving interpolation (VPI) method, together with the distance-decay principle, were used to derive emission weights for each grid based on its proximity to highways, roads, railroads, waterways, and airports. The total CO2 emission value summed from the grids within a county is made to be equal to the original county-level estimate, thus enforcing the volume-preserving property. The method was applied to downscale the transportation-related CO2 emission values by county (i.e. parish) for the state of Louisiana into 1 km2 grids. The results reveal a more realistic spatial pattern of CO2 emission from transportation, which can be used to identify the emission ‘hot spots’. Of the four highest transportation-related CO2 emission hotspots in Louisiana, high-emission grids literally covered the entire East Baton Rouge Parish and Orleans Parish, whereas CO2 emission in Jefferson Parish (New Orleans suburb) and Caddo Parish (city of Shreveport) were more unevenly distributed. We argue that the new method is sound in principle, flexible in practice, and the resultant estimates are more accurate than previous gridding approaches. PMID:26997973

  15. On the use of IT investment assessment methods in the area of spatial data infrastructure

    NASA Astrophysics Data System (ADS)

    Zwirowicz-Rutkowska, Agnieszka

    2016-06-01

    One of the important issues concerning development of spatial data infrastructures (SDIs) is the carrying out of economic and financial analysis. It is essential to determine expenses and also assess effects resulting from the development and use of infrastructures. Costs and benefits assessment could be associated with assessment of the infrastructure effectiveness and efficiency as well as the infrastructure value, understood as the infrastructure impact on economic aspects of an organisational performance, both of an organisation which realises an SDI project and all users of the infrastructure. The aim of this paper is an overview of various assessment methods of investment as well as an analysis of different types of costs and benefits used for information technology (IT) projects. Based on the literature, the analysis of the examples of the use of these methods in the area of spatial data infrastructures is also presented. Furthermore, the issues of SDI projects and investments are outlined. The results of the analysis indicate usefulness of the financial methods from different fields of management in the area of SDI building, development and use. The author proposes, in addition to the financial methods, the adaptation of the various techniques used for IT investments and their development, taking into consideration the SDI specificity for the purpose of assessment of different types of costs and benefits and integration of financial aspects with non-financial ones. Among the challenges are identification and quantification of costs and benefits, as well as establishing measures which would fit the characteristics of the SDI project and artefacts resulting from the project realisation. Moreover, aspects of subjectivity and variability in time should be taken into account as the consequences of definite goals and policies as well as business context of organisation undertaking the project or using its artefacts and also investors.

  16. Inter-comparison of spatial upscaling methods for evaluation of satellite-based soil moisture

    NASA Astrophysics Data System (ADS)

    Qin, Jun; Zhao, Long; Chen, Yingying; Yang, Kun; Yang, Yaping; Chen, Zhuoqi; Lu, Hui

    2015-04-01

    Soil moisture is a key factor in energy and water cycles. Many satellite missions have been planned and implemented for retrieving soil moisture globally. Because the spatial representativeness of a point-scale soil moisture station is rather limited, a station network needs setting up for scale-matching validation of satellite-based soil moisture products. Even so, an upscaling procedure is needed to upscale these station soil moisture values into area-wide one. However, such a procedure itself introduces uncertainties into the upscaled soil moisture. In this study, four upscaling methods (simple average, block kriging, model-based, and apparent-thermal-inertia-based) are inter-compared according to their performance stability for evaluation of soil moisture estimated by assimilating microwave signals into a land surface model. It is found that the performance of the model-based upscaling approach is the most unstable because model simulations are full of uncertainties for representing spatial variability of soil moisture. The block kriging upscaling method performs not worse than the simple averaging approach; the former may generate more representative soil moisture if the range of the soil moisture semivariogram used in the block kriging is comparable to the extent of a satellite footprint. The apparent-thermal-inertia-based upscaling is the most stable one, which has been developed with the aid of high-resolution satellite thermal data. All analyses indicate that choosing a suitable upscaling approach is important for the effective evaluation of satellite-based soil moisture. Otherwise, uncertainties hiding in the upscaling method will be incorrectly attributed to errors in satellite products, undermining our confidence in implementing them into practice.

  17. The Role of Need for Contraception in the Evaluation of Interventions to Improve Access to Family-Planning Methods

    ERIC Educational Resources Information Center

    Leon, Federico R.; Lundgren, Rebecka; Sinai, Irit; Jennings, Victoria

    2011-01-01

    A nonrandomized experiment carried out in Jharkhand, India, shows how the effects of interventions designed to improve access to family-planning methods can be erroneously regarded as trivial when contraceptive use is utilized as dependent variable, ignoring women's need for contraception. Significant effects of the intervention were observed on…

  18. 47 CFR 51.321 - Methods of obtaining interconnection and access to unbundled elements under section 251 of the Act.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... to unbundled elements under section 251 of the Act. 51.321 Section 51.321 Telecommunication FEDERAL... of Incumbent Local Exchange Carriers § 51.321 Methods of obtaining interconnection and access to... the area in which space was denied, without charge, within ten days of the receipt of the...

  19. Evaluation of angular quadrature and spatial differencing schemes for discrete ordinates method in rectangular furnaces

    SciTech Connect

    Selcuk, N.; Kayakol, N.

    1996-11-01

    Effects of order of approximation (S{sub 2} and S{sub 4}), angular quadrature (S{sub n} and S{sub n}{prime}) and spatial differencing (diamond and variable-weight) schemes, on the predictive accuracy of discrete ordinates method were investigated by predicting the distributions of radiative flux density and source term of a rectangular enclosure problem and comparing the results with exact solutions produced previously. The enclosure problem is based on data reported earlier on a large-scale experimental furnace with steep temperature gradients. It is a black-walled enclosure containing an absorbing-emitting medium of constant properties. Comparisons show that better agreement is obtained in radiative energy source terms than in flux densities and that the order of approximation plays a more significant role than angular quadrature and spatial differencing schemes in the accuracy of predicted radiative flux densities and radiative energy source terms. Only slight improvements are obtained when S{sub n} and variable-weight differencing schemes are employed.

  20. Research on large spatial coordinate automatic measuring system based on multilateral method

    NASA Astrophysics Data System (ADS)

    Miao, Dongjing; Li, Jianshuan; Li, Lianfu; Jiang, Yuanlin; Kang, Yao; He, Mingzhao; Deng, Xiangrui

    2015-10-01

    To measure the spatial coordinate accurately and efficiently in large size range, a manipulator automatic measurement system which based on multilateral method is developed. This system is divided into two parts: The coordinate measurement subsystem is consists of four laser tracers, and the trajectory generation subsystem is composed by a manipulator and a rail. To ensure that there is no laser beam break during the measurement process, an optimization function is constructed by using the vectors between the laser tracers measuring center and the cat's eye reflector measuring center, then an orientation automatically adjust algorithm for the reflector is proposed, with this algorithm, the laser tracers are always been able to track the reflector during the entire measurement process. Finally, the proposed algorithm is validated by taking the calibration of laser tracker for instance: the actual experiment is conducted in 5m × 3m × 3.2m range, the algorithm is used to plan the orientations of the reflector corresponding to the given 24 points automatically. After improving orientations of some minority points with adverse angles, the final results are used to control the manipulator's motion. During the actual movement, there are no beam break occurs. The result shows that the proposed algorithm help the developed system to measure the spatial coordinates over a large range with efficiency.

  1. Spatial memory: Theoretical basis and comparative review on experimental methods in rodents.

    PubMed

    Paul, Carrillo-Mora; Magda, Giordano; Abel, Santamaría

    2009-11-01

    The assessment of learning and memory in animal models has been widely employed in scientific research for a long time. Among these models, those representing diseases with primary processes of affected memory - such as amnesia, dementia, brain aging, etc. - studies dealing with the toxic effects of specific drugs, and other exploring neurodevelopment, trauma, epilepsy and neuropsychiatric disorders, are often called on to employ these tools. There is a diversity of experimental methods assessing animal learning and memory skills. Overall, mazes are the devices mostly used today to test memory in rodents; there are several types of them, but their real usefulness, advantages and applications remain to be fully established and depend on the particular variant selected by the experimenter. The aims of the present article are first, to briefly review the accumulated knowledge in regard to spatial memory tasks; second, to bring the reader information on the different types of rodent mazes available to test spatial memory; and third, to elucidate the usefulness and limitations of each of these devices. PMID:19467271

  2. Airborne gamma-ray spectrometer survey data application in spatial methods

    SciTech Connect

    Bresnahan, P.J.

    1996-12-31

    The purpose of this research was to develop a methodology that used geographic information system (GIS) tools to convert airborne gamma-ray spectrometer (AGRS) survey data to various spatial data formats for use in radiological hazard mapping and risk assessments. The importance of this conversion methodology results from the versatility and consistency of spatial interpolations using commercially supported software as opposed to previous methods. Maps of interpolated AGRS data provide potential radiological hazard boundaries, delineated by user-defined limits, to guide intense field surveys. Resulting GIS products may be combined with other risk assessment inputs to model and monitor hazardous environments. The AGRS data used in this research was collected during the 1991 sitewide survey at Savannah River site (SRS) as part of the comprehensive integrated remote sensing (CIRS) program conducted by EG&G for the SRS. The AGRS survey component of the program is designed to provide a database for studying the transport of manufactured radionuclides through the environment at the SRS and surrounding areas. The AGRS data have historically been presented only in hardcopy format as acetate overlays on aerial photography. Recently, digital files representing contoured isotopic response have been delivered to the SRS as GIS themes. Since AGRS data are often a collection of dense sample points, interpolation of the data has previously been conducted by connecting points in series along flight paths. To improve on the original algorithm used to contour AGRS data, a triangulated irregular network (TIN) was used as the data model for contour and raster generation.

  3. A Rapid Monitoring and Evaluation Method of Schistosomiasis Based on Spatial Information Technology.

    PubMed

    Wang, Yong; Zhuang, Dafang

    2015-12-01

    Thanks to Spatial Information Technologies (SITs) such as Remote Sensing (RS) and Geographical Information System (GIS) that are being quickly developed and updated, SITs are being used more widely in the public health field. The use of SITs to study the characteristics of the temporal and spatial distribution of Schistosoma japonicum and to assess the risk of infection provides methods for the control and prevention of schistosomiasis japonica has gradually become a hot topic in the field. The purpose of the present paper was to use RS and GIS technology to develop an efficient method of prediction and assessment of the risk of schistosomiasis japonica. We choose the Yueyang region, close to the east DongTing Lake (Hunan Province, China), as the study area, where a recent serious outbreak of schistosomiasis japonica took place. We monitored and evaluated the transmission risk of schistosomiasis japonica in the region using SITs. Water distribution data were extracted from RS images. The ground temperature, ground humidity and vegetation index were calculated based on RS images. Additionally, the density of oncomelania snails, which are the Schistosoma japonicum intermediate host, was calculated on the base of RS data and field measurements. The spatial distribution of oncomelania snails was explored using SITs in order to estimate the area surrounding the residents with transmission risk of schistosomiasis japonica. Our research result demonstrated: (1) the risk factors for the transmission of schistosomiasis japonica were closely related to the living environment of oncomelania snails. Key factors such as water distribution, ground temperature, ground humidity and vegetation index can be quickly obtained and calculated from RS images; (2) using GIS technology and a RS deduction technique along with statistical regression models, the density distribution model of oncomelania snails could be quickly built; (3) using SITs and analysis with overlaying population

  4. A Rapid Monitoring and Evaluation Method of Schistosomiasis Based on Spatial Information Technology

    PubMed Central

    Wang, Yong; Zhuang, Dafang

    2015-01-01

    Thanks to Spatial Information Technologies (SITs) such as Remote Sensing (RS) and Geographical Information System (GIS) that are being quickly developed and updated, SITs are being used more widely in the public health field. The use of SITs to study the characteristics of the temporal and spatial distribution of Schistosoma japonicum and to assess the risk of infection provides methods for the control and prevention of schistosomiasis japonica has gradually become a hot topic in the field. The purpose of the present paper was to use RS and GIS technology to develop an efficient method of prediction and assessment of the risk of schistosomiasis japonica. We choose the Yueyang region, close to the east DongTing Lake (Hunan Province, China), as the study area, where a recent serious outbreak of schistosomiasis japonica took place. We monitored and evaluated the transmission risk of schistosomiasis japonica in the region using SITs. Water distribution data were extracted from RS images. The ground temperature, ground humidity and vegetation index were calculated based on RS images. Additionally, the density of oncomelania snails, which are the Schistosoma japonicum intermediate host, was calculated on the base of RS data and field measurements. The spatial distribution of oncomelania snails was explored using SITs in order to estimate the area surrounding the residents with transmission risk of schistosomiasis japonica. Our research result demonstrated: (1) the risk factors for the transmission of schistosomiasis japonica were closely related to the living environment of oncomelania snails. Key factors such as water distribution, ground temperature, ground humidity and vegetation index can be quickly obtained and calculated from RS images; (2) using GIS technology and a RS deduction technique along with statistical regression models, the density distribution model of oncomelania snails could be quickly built; (3) using SITs and analysis with overlaying population

  5. Provider imposed restrictions to clients’ access to family planning in urban Uttar Pradesh, India: a mixed methods study

    PubMed Central

    2013-01-01

    Background Medical barriers refer to unnecessary policies or procedures imposed by health care providers that are not necessarily medically advised; these restrictions impede clients’ access to family planning (FP). This mixed methods study investigates provider imposed barriers to provision of FP using recent quantitative and qualitative data from urban Uttar Pradesh, India. Methods Baseline quantitative data were collected in six cities in Uttar Pradesh, India from service delivery points (SDP), using facility audits, exit interviews, and provider surveys; for this study, the focus is on the provider surveys. More than 250 providers were surveyed in each city. Providers were asked about the FP methods they provide, and if they restrict clients’ access to each method based on age, parity, partner consent, or marital status. For the qualitative research, we conducted one-on-one interviews with 21 service providers in four of the six cities in Uttar Pradesh. Each interview lasted approximately 45 minutes. Results The quantitative findings show that providers restrict clients’ access to spacing and long-acting and permanent methods of FP based on age, parity, partner consent and marital status. Qualitative findings reinforce that providers, at times, make judgments about their clients’ education, FP needs and ability to understand FP options thereby imposing unnecessary barriers to FP methods. Conclusions Provider restrictions on FP methods are common in these urban Uttar Pradesh sites. This means that women who are young, unmarried, have few or no children, do not have the support of their partner, or are less educated may not be able to access or use FP or their preferred method. These findings highlight the need for in-service training for staff, with a focus on reviewing current guidelines and eligibility criteria for provision of methods. PMID:24365015

  6. Study of spatial and energy characteristics of relativistic electron bursts in magnetosphere with robust methods

    NASA Astrophysics Data System (ADS)

    Zharaspayev, T. R.; Aleksandrin, S. Yu; Koldashov, S. V.

    2016-02-01

    Electron bursts are well-known phenomena of fast increase in particle fluxes in near-Earth space. Powerful local geophysical events like earthquakes or thunderstorms can induce precipitation of electrons with defined energy spectrum from the radiation belt, which would be registered as fast increase in particle count rate on board the low orbit satellite. Using particle burst energy spectrum evolution in time one can detect the area of particles precipitation. Background particles are registered by instruments too and can't be separated from burst particles. High level of background particles can have large impact on detection of the area of particles precipitation. A robust regression method to solve problem of background particles is introduced and compared with standard method of linear regression. Results of comparison between various data analysis methods in application to study of spatial and energy characteristics of relativistic electron bursts in the Earth magnetosphere are presented in this work. Robust method proved to be optimal for data analysis of energy spectrum evolution in time for search of zones of local radiation belt disturbances.

  7. Method for generating spatial and temporal synthetic hourly rainfall in the Valley of Mexico

    NASA Astrophysics Data System (ADS)

    Mendoza-Resendiz, Alejandro; Arganis-Juarez, Maritza; Dominguez-Mora, Ramon; Echavarria, Bernardo

    2013-10-01

    Hydrological risk analyses require a dense pluviometer network and a long period of records with an adequate time resolution; usually pluviometer networks have short periods of simultaneous records, so it is required to extend the number of records by means of synthetically generated rainfall events. This paper describes the development and implementation of a method based on a daily rainfall disaggregation for generating synthetic rainfall events distributed spatially and temporally. It uses the information recorded in 49 rain-gauge stations in the network of the basin of the Valley of Mexico during the rainy season from 1988 to 2006. Within various methods found in the literature, we consider that this one provides a greater simplicity for a practical implementation. The tests carried out showed that rainfall events generated with this method properly reproduce the statistical parameters of the historical records, including those that are not implicitly incorporated in the model, as is the case of the synthetic hourly rainfall, whose statistical values are virtually identical to the historical ones despite that the proposed method only uses the probability distribution of maximum daily rainfall.

  8. Method for Evaluation of Outage Probability on Random Access Channel in Mobile Communication Systems

    NASA Astrophysics Data System (ADS)

    Kollár, Martin

    2012-05-01

    In order to access the cell in all mobile communication technologies a so called random-access procedure is used. For example in GSM this is represented by sending the CHANNEL REQUEST message from Mobile Station (MS) to Base Transceiver Station (BTS) which is consequently forwarded as an CHANNEL REQUIRED message to the Base Station Controller (BSC). If the BTS decodes some noise on the Random Access Channel (RACH) as random access by mistake (so- called ‘phantom RACH') then it is a question of pure coincidence which èstablishment cause’ the BTS thinks to have recognized. A typical invalid channel access request or phantom RACH is characterized by an IMMEDIATE ASSIGNMENT procedure (assignment of an SDCCH or TCH) which is not followed by sending an ESTABLISH INDICATION from MS to BTS. In this paper a mathematical model for evaluation of the Power RACH Busy Threshold (RACHBT) in order to guaranty in advance determined outage probability on RACH is described and discussed as well. It focuses on Global System for Mobile Communications (GSM) however the obtained results can be generalized on remaining mobile technologies (ie WCDMA and LTE).

  9. A sampling method for improving the representation of spatially varying precipitation and soil moisture using the Simple Biosphere Model

    NASA Astrophysics Data System (ADS)

    Medina, Isaac D.; Denning, A. Scott; Baker, Ian T.; Ramirez, Jorge A.; Randall, David A.

    2014-03-01

    spatially varying precipitation for current grid length scales used in General Circulation Models (GCMs) is a continuing challenge. Furthermore, to fully capture the hydrologic effects of nonuniform precipitation, a representation of soil moisture heterogeneity and distribution of spatially varying precipitation must exist within the same framework. For this study, the explicit and sampling methods of Sellers et al. (2007) are tested off-line using the Simple Biosphere Model (SiB3) in an arid, semiarid, and wet site, and are numerically compared to the bulk method, which is currently used in GCMs. To carry out the numerical experiments, an arbitrary grid area was defined by (1) a single instance of SiB3 (bulk method), (2) 100 instances of SiB3 (explicit method), and (3) less than 100 instances of SiB3 (sampling method). Precipitation was randomly distributed over fractions of the grid area for the explicit and sampling methods, while the standard SiB3 exponential distribution relating precipitation intensity to the grid area wet fraction was used in the bulk method. Comparing the sampling and bulk method to the explicit method indicates that 10 instances of SiB3 in the sampling method better captures the spatial variability in soil moisture and grid area flux calculations produced by the explicit method, and deals realistically with spatially varying precipitation at little additional computational cost to the bulk method.

  10. (1 + 2)-Dimensional sub-strongly nonlocal spatial optical solitons: Perturbation method

    NASA Astrophysics Data System (ADS)

    Ren, Hongyan; Ouyang, Shigen; Guo, Qi; Wu, Lijun

    2007-07-01

    By extending the (1 + 1)-dimensional [(1 + 1)-D] perturbation method suggested by Ouyang et al. [S. Ouyang, Q. Guo, W. Hu, Phys. Rev. E. 74 (2006) 036622] to the (1 + 2)-D case, we obtain a fundamental soliton solution to the (1 + 2)-D nonlocal nonlinear Schrödinger equation (NNLSE) with a Gaussian-type response function for the sub-strongly nonlocal case. Numerical simulations show that the soliton solution obtained in this paper can describe the soliton states in both the sub-strongly nonlocal case and the strongly nonlocal case. It is found that the phase constant and the power of the (1 + 2)-D strongly nonlocal spatial optical soliton with a Gaussian-type response function are both in inverse proportion to the 4th power of its beam width.

  11. High order spatial expansion for the method of characteristics applied to 3-D geometries

    SciTech Connect

    Naymeh, L.; Masiello, E.; Sanchez, R.

    2013-07-01

    The method of characteristics is an efficient and flexible technique to solve the neutron transport equation and has been extensively used in two-dimensional calculations because it permits to deal with complex geometries. However, because of a very fast increase in storage requirements and number of floating operations, its direct application to three-dimensional routine transport calculations it is not still possible. In this work we introduce and analyze several modifications aimed to reduce memory requirements and to diminish the computing burden. We explore high-order spatial approximation, the use of intermediary trajectory-dependent flux expansions and the possibility of dynamic trajectory reconstruction from local tracking for typed subdomains. (authors)

  12. Computational methods for the identification of spatially varying stiffness and damping in beams

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Rosen, I. G.

    1986-01-01

    A numerical approximation scheme for the estimation of functional parameters in Euler-Bernoulli models for the transverse vibration of flexible beams with tip bodies is developed. The method permits the identification of spatially varying flexural stiffness and Voigt-Kelvin viscoelastic damping coefficients which appear in the hybrid system of ordinary and partial differential equations and boundary conditions describing the dynamics of such structures. An inverse problem is formulated as a least squares fit to data subject to constraints in the form of a vector system of abstract first order evolution equations. Spline-based finite element approximations are used to finite dimensionalize the problem. Theoretical convergence results are given and numerical studies carried out on both conventional (serial) and vector computers are discussed.

  13. Comparison of Statistical Methods for Assessing Spatial Correlations Between Maps of Different Arterial Properties.

    PubMed

    Rowland, Ethan M; Mohamied, Yumnah; Yean Chooi, K; Bailey, Emma L; Weinberg, Peter D

    2015-10-01

    Assessing the anatomical correlation of atherosclerosis with biomechanical localizing factors is hindered by spatial autocorrelation (SA), wherein neighboring arterial regions tend to have similar properties rather than being independent, and by the use of aggregated data, which artificially inflates correlation coefficients. Resampling data at lower resolution or reducing degrees-of-freedom in significance tests negated effects of SA but only in artificial situations where it occurred at a single length scale. Using Fourier or wavelet transforms to generate autocorrelation-preserving surrogate datasets, and thus to compute the null distribution, avoided this problem. Bootstrap methods additionally circumvented the errors caused by aggregating data. The bootstrap technique showed that wall shear stress (WSS) was significantly correlated with atherosclerotic lesion frequency and endothelial nuclear elongation, but not with the permeability of the arterial wall to albumin, in immature rabbits. PMID:26201866

  14. Method for nanoscale spatial registration of scanning probes with substrates and surfaces

    NASA Technical Reports Server (NTRS)

    Wade, Lawrence A. (Inventor)

    2010-01-01

    Embodiments in accordance with the present invention relate to methods and apparatuses for aligning a scanning probe used to pattern a substrate, by comparing the position of the probe to a reference location or spot on the substrate. A first light beam is focused on a surface of the substrate as a spatial reference point. A second light beam then illuminates the scanning probe being used for patterning. An optical microscope images both the focused light beam, and a diffraction pattern, shadow, or light backscattered by the illuminated scanning probe tip of a scanning probe microscope (SPM), which is typically the tip of the scanning probe on an atomic force microscope (AFM). Alignment of the scanning probe tip relative to the mark is then determined by visual observation of the microscope image. This alignment process may be repeated to allow for modification or changing of the scanning probe microscope tip.

  15. A method for spatially explicit representation of sub-watershed sediment yield, Southern California, USA.

    PubMed

    Booth, Derek B; Leverich, Glen; Downs, Peter W; Dusterhoff, Scott; Araya, Sebastian

    2014-05-01

    We present here a method to integrate geologic, topographic, and land-cover data in a geographic information system to provide a fine-scale, spatially explicit prediction of sediment yield to support management applications. The method is fundamentally qualitative but can be quantified using preexisting sediment-yield data, where available, to verify predictions using other independent data sets. In the 674-km(2) Sespe Creek watershed of southern California, 30 unique "geomorphic landscape units" (GLUs, defined by relatively homogenous areas of geology, hillslope gradient, and land cover) provide a framework for discriminating relative rates of sediment yield across this landscape. Field observations define three broad groupings of GLUs that are well-associated with types, relative magnitudes, and rates of erosion processes. These relative rates were then quantified using sediment-removal data from nearby debris basins, which allow relatively low-precision but robust calculations of both local and whole-watershed sediment yields, based on the key assumption that minimal sediment storage throughout most of the watershed supports near-equivalency of long-term rates of hillslope sediment production and watershed sediment yield. The accuracy of these calculations can be independently assessed using geologically inferred uplift rates and integrated suspended sediment measurements from mainstem Sespe Creek, which indicate watershed-averaged erosion rates between about 0.6-1.0 mm year(-1) and corresponding sediment yields of about 2 × 10(3) t km(-2) year(-1). A spatially explicit representation of sediment production is particularly useful in a region where wildfires, rapid urban development, and the downstream delivery of upstream sediment loads are critical drivers of both geomorphic processes and land-use management. PMID:24567071

  16. Inverse Method for Estimating the Spatial Variability of Soil Particle Size Distribution from Observed Soil Moisture

    SciTech Connect

    Pan, Feifei; Peters-lidard, Christa D.; King, Anthony Wayne

    2010-11-01

    Soil particle size distribution (PSD) (i.e., clay, silt, sand, and rock contents) information is one of critical factors for understanding water cycle since it affects almost all of water cycle processes, e.g., drainage, runoff, soil moisture, evaporation, and evapotranspiration. With information about soil PSD, we can estimate almost all soil hydraulic properties (e.g., saturated soil moisture, field capacity, wilting point, residual soil moisture, saturated hydraulic conductivity, pore-size distribution index, and bubbling capillary pressure) based on published empirical relationships. Therefore, a regional or global soil PSD database is essential for studying water cycle regionally or globally. At the present stage, three soil geographic databases are commonly used, i.e., the Soil Survey Geographic database, the State Soil Geographic database, and the National Soil Geographic database. Those soil data are map unit based and associated with great uncertainty. Ground soil surveys are a way to reduce this uncertainty. However, ground surveys are time consuming and labor intensive. In this study, an inverse method for estimating mean and standard deviation of soil PSD from observed soil moisture is proposed and applied to Throughfall Displacement Experiment sites in Walker Branch Watershed in eastern Tennessee. This method is based on the relationship between spatial mean and standard deviation of soil moisture. The results indicate that the suggested method is feasible and has potential for retrieving soil PSD information globally from remotely sensed soil moisture data.

  17. Oxide Defect Engineering Methods for Valence Change (VCM) Resistive Random Access Memories

    NASA Astrophysics Data System (ADS)

    Capulong, Jihan O.

    Electrical switching requirements for resistive random access memory (ReRAM) devices are multifaceted, based on device application. Thus, it is important to obtain an understanding of these switching properties and how they relate to the oxygen vacancy concentration and oxygen vacancy defects. Oxygen vacancy defects in the switching oxide of valence-change-based ReRAM (VCM ReRAM) play a significant role in device switching properties. Oxygen vacancies facilitate resistive switching as they form the conductive filament that changes the resistance state of the device. This dissertation will present two methods of modulating the defect concentration in VCM ReRAM composed of Pt/HfOx/Ti stack: 1) rapid thermal annealing (RTA) in Ar using different temperatures, and 2) doping using ion implantation under different dose levels. Metrology techniques such as x-ray diffractometry (XRD), x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy were utilized to characterize the HfOx switching oxide, which provided insight on the material properties and oxygen vacancy concentration in the oxide that was used to explain the changes in the electrical properties of the ReRAM devices. The resulting impact on the resistive switching characteristics of the devices, such as the forming voltage, set and reset threshold voltages, ON and OFF resistances, resistance ratio, and switching dispersion or uniformity were explored and summarized. Annealing in Ar showed significant impact on the forming voltage, with as much as 45% (from 22V to 12 V) of improvement, as the annealing temperature was increased. However, drawbacks of a higher oxide leakage and worse switching uniformity were seen with increasing annealing temperature. Meanwhile, doping the oxide by ion implantation showed significant effects on the resistive switching characteristics. Ta doping modulated the following switching properties with increasing dose: a) the reduction of the forming voltage, and Vset

  18. [Evaluating the performance of the UCLA method for spatially downscaling soil moisture products using three Ts/VI indices].

    PubMed

    Ling, Zi-Wei; He, Long-Bin; Zeng, Hui

    2014-02-01

    Soil moisture products derived from microwave remote sensing data are commonly used in the studies of large-scale water resources or climate change. However, the spatial resolutions of these products are usually too coarse to be used in regional- or watershed-scale studies. Therefore, it is necessary to spatially downscale the coarse-resolution soil moisture products for use in regional- or watershed-scale studies. The UCLA method is one of the methods for spatially downscaling soil moisture products. In this method, the spatial indices (Ts/VI indices) calculated from land surface temperature and vegetation index are used as auxiliary variables for spatial downscaling. In this paper, we compared the performance of the UCLA method for spatially downscaling the coarse-resolution AMSR-E soil moisture products, using three Ts/VI indices as auxiliary variables, i. e., the soil wetness index (SW), temperature vegetation dryness index (TVDI), and vegetation temperature condition index (VTCI). These auxiliary variables were calculated from the products of MODIS land surface temperature (MYD11A1) and MODIS vegetation index (MYD13A2). The downscaled results using the three Ts/VI indices were all reasonable. However, the downscaled results using TVDI and VTCI were better than using SW. Therefore, we concluded that TVDI and VTCI are more suitable than SW to be used as the auxiliary variable when applying the UCLA method for downscaling soil moisture products. Finally, we discussed the error sources of applying the UCLA method, such as measurement errors of coarse resolution soil products, calculation errors from spatial indices, and errors from the UCLA method itself, and we also discussed the potential improvements of future research. PMID:24830256

  19. Beyond the Test Score: A Mixed Methods Analysis of a College Access Intervention in Chile

    ERIC Educational Resources Information Center

    Treviño, Ernesto; Scheele, Judith; Flores, Stella M.

    2014-01-01

    Using both quantitative and qualitative analyses, we examine the role of a college access intervention in the enrollment and persistence outcomes of low-income students in Chile modeled partially after a Texas admissions program. We find that, although students from the program have a mean cumulative GPA significantly lower than that of their…

  20. Videophone Technology and Students with Deaf-Blindness: A Method for Increasing Access and Communication

    ERIC Educational Resources Information Center

    Emerson, Judith; Bishop, John

    2012-01-01

    Introduction: Seeing the Possibilities with Videophone Technology began as research project funded by the National Center for Technology Innovation. The project implemented a face-to-face social networking program for students with deaf-blindness to investigate the potential for increasing access and communication using videophone technology.…

  1. Beyond the Repository: A Mixed Method Approach to Providing Access to Collections Online

    ERIC Educational Resources Information Center

    Garrison, Brian Wade

    2013-01-01

    After providing access to over 100 video interviews conducted by a professor with notable entertainers and personalities from film through an institutional repository, an experiment was conducted to discover whether a larger audience could be gained by adding a subset of 32 of these videos to YouTube. The results, over 400,000 views, indicate that…

  2. Usability of a Low-Cost Head Tracking Computer Access Method following Stroke.

    PubMed

    Mah, Jasmine; Jutai, Jeffrey W; Finestone, Hillel; Mckee, Hilary; Carter, Melanie

    2015-01-01

    Assistive technology devices for computer access can facilitate social reintegration and promote independence for people who have had a stroke. This work describes the exploration of the usefulness and acceptability of a new computer access device called the Nouse™ (Nose-as-mouse). The device uses standard webcam and video recognition algorithms to map the movement of the user's nose to a computer cursor, thereby allowing hands-free computer operation. Ten participants receiving in- or outpatient stroke rehabilitation completed a series of standardized and everyday computer tasks using the Nouse™ and then completed a device usability questionnaire. Task completion rates were high (90%) for computer activities only in the absence of time constraints. Most of the participants were satisfied with ease of use (70%) and liked using the Nouse™ (60%), indicating they could resume most of their usual computer activities apart from word-processing using the device. The findings suggest that hands-free computer access devices like the Nouse™ may be an option for people who experience upper motor impairment caused by stroke and are highly motivated to resume personal computing. More research is necessary to further evaluate the effectiveness of this technology, especially in relation to other computer access assistive technology devices. PMID:26427744

  3. Immigration, ethnicity, and accessibility to culturally diverse family physicians.

    PubMed

    Wang, Lu

    2007-09-01

    The study concerns ethnicity, spatial equity, and healthcare access in the context of diversity and integration. The paper first explores how Chinese immigrants in the Toronto Census Metropolitan Area choose between ethnic Chinese family physicians and other family physicians, based on a probability survey. It then applies and modifies gravity-type accessibility measures, of which a special type is the so-called floating catchment area (FCA) method, to evaluate three types of geographical accessibility in family physician utilization. The study suggests a certain degree of spatial inequality among Chinese immigrants in accessing culturally sensitive care. The paper yields important methodological and policy implications. PMID:17174590

  4. A New Method for Quantifying Compaction Rates and Their Spatial Variability in the Mississippi Delta

    NASA Astrophysics Data System (ADS)

    Chamberlain, E. L.; Shen, Z.; Tornqvist, T. E.; Mauz, B.

    2014-12-01

    Understanding the rates and drivers of subsidence in deltas is essential to manage subaerial land in these naturally ephemeral settings. Subsidence in deltaic settings may be driven by deep crustal processes including isostasy and faulting, compaction of Holocene deposits, and anthropogenic activities such as groundwater management and fluid withdrawal. Here, we offer a new method to measure compaction rates and their spatial variability in the Mississippi Delta (MD) to test the null hypotheses that compaction increases seaward and is a major driver of subsidence. Late Holocene compaction rates are measured using the mouthbar-overbank stratigraphic boundary. This boundary generally corresponds to mean low tide level; therefore its present-day height relative to coeval mean low tide level is a measure of compaction since the formation of this boundary. The age of this boundary is established through quartz OSL dating, and Holocene relative sea level history in the MD has been well-established. The common occurrence of the mouthbar-overbank boundary in progradational fluviodeltaic successions in the MD makes it possible to study the spatial variability of compaction rates. We also compare displacement rates for this boundary directly north and south of two coast-parallel normal faults. Results show that late Holocene compaction rates in the Lafourche subdelta of the MD are on the order of a few mm/yr, significantly lower than historical surface subsidence rates for the region. Therefore, the elevated historical surface subsidence rates are likely the result of human alteration of the delta such as fluid withdrawal and groundwater management. Compaction rates do not increase seaward as generally assumed, and instead seem to be driven primarily by the thickness of sediments overlying the mouthbar sands. Thus, the highest rates are documented relatively inland. In addition, we do not find a significant increase in subsidence across normal faults in our study area

  5. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    DOEpatents

    Yeung, E.S.; Chen, G.

    1990-05-01

    A method and means are disclosed for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived. 15 figs.

  6. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    DOEpatents

    Yeung, Edward S.; Chen, Guoying

    1990-05-01

    A method and means for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived.

  7. Spatial interpolation of precipitation indexes in Sierra Nevada (Spain): comparing the performance of some interpolation methods

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Oliva, Marc; Misiune, Ieva

    2015-08-01

    The objective of this paper is to examine the spatial distribution of several precipitation indexes in Sierra Nevada, Spain: mean annual number of wet days (R ≥ 1 mm), mean annual number of heavy rainy days (R ≥ 10 mm) and mean annual number of very heavy precipitation days (R ≥ 20 mm) and test the performance of several interpolation methods using these variables. In total, 17 univariate and multivariate methods were tested. A set of 36 metereological stations distributed in Sierra Nevada and neighbouring areas was analysed in this study. The original data did not followed the normal distribution; thus, a logarithm was applied to data meet normality purposes. Interpolator's performance was assessed using the root mean square error generated from cross-validation. The results showed that the mean annual R ≥ 10 mm and R ≥ 20 mm have a higher variability than R ≥ 1 mm. While the elevation and longitude did not show a significant correlation with the studied indexes, the latitude (i.e. distance to the sea) showed a significant negative correlation. The regressions carried out confirmed that elevation was the covariate with higher capacity to explain the variability of the indexes. The incorporation of elevation and longitude slightly increased the explanation capacity of the models. The data of LogR ≥ 1 mm, LogR ≥ 10 mm and LogR ≥ 20 mm displayed a clustered pattern, especially the last two indexes that also showed a strong spatial dependency attributed to the effects of local topography, slope, aspect and valley orientation. The best fitted variogram model to LogR ≥ 1 mm was the linear one while for the LogR ≥ 10 mm and LogR ≥ 20 mm, the Gaussian was the most appropriate. The best interpolator for LogR ≥ 1 mm was the local polinomyal with the power of 1, whereas for LogR ≥ 10 mm and LogR ≥ 20 mm, regression kriging (ROK) using as auxiliary variables the elevation, latitude and longitude was the most accurate. ROK methods significantly

  8. Capturing peripersonal spatial neglect: an electronic method to quantify visuospatial processes.

    PubMed

    Vaes, Nathalie; Lafosse, Christophe; Nys, Gudrun; Schevernels, Hanne; Dereymaeker, Lutgart; Oostra, Kristine; Hemelsoet, Dimitri; Vingerhoets, Guy

    2015-03-01

    Computerized as well as paper-and-pencil tasks are applied in mapping visuospatial neglect in experimental research and clinical practice. This article presents a new kind of computer-based assessment method, using an electronic pen display and user-friendly software. The approach is tailored to specific spatial processes and highlights the usefulness of a pen display in neglect patients. The advantages of the introduced method are illustrated by a recently designed battery of classic, as well as new, types of tests. The development of the appropriate stimuli and the assorted scoring systems is addressed, as well as the resulting types of task implementation and data generation. The diagnostic value of the different visuospatial neglect tests is demonstrated by comparative analyses between a neglect group and a control group. Among the benefits of the proposed assessment method are (1) the opportunity to perform standardized repeated measurements to quantify recovery, (2) online performance monitoring, (3) flexible employment, (4) the collection of exact data over a short period, and (5) the easy availability of more refined quantitative as well as interesting qualitative information, especially as compared to classic or paper-and-pencil tasks. To indicate that this method also lends itself well to measures for treatment procedures, an illustration is given with respect to specific measurements during prism adaptation. The tasks of the Visuospatial Neglect Test Battery and the prism adaptation measures are illustrated by a case study. The outlined applications are discussed with respect to experimental as well as clinical purposes. PMID:24567147

  9. A general method for spatially coarse-graining Metropolis Monte Carlo simulations onto a lattice

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Seider, Warren D.; Sinno, Talid

    2013-03-01

    A recently introduced method for coarse-graining standard continuous Metropolis Monte Carlo simulations of atomic or molecular fluids onto a rigid lattice of variable scale [X. Liu, W. D. Seider, and T. Sinno, Phys. Rev. E 86, 026708 (2012)], 10.1103/PhysRevE.86.026708 is further analyzed and extended. The coarse-grained Metropolis Monte Carlo technique is demonstrated to be highly consistent with the underlying full-resolution problem using a series of detailed comparisons, including vapor-liquid equilibrium phase envelopes and spatial density distributions for the Lennard-Jones argon and simple point charge water models. In addition, the principal computational bottleneck associated with computing a coarse-grained interaction function for evolving particle positions on the discretized domain is addressed by the introduction of new closure approximations. In particular, it is shown that the coarse-grained potential, which is generally a function of temperature and coarse-graining level, can be computed at multiple temperatures and scales using a single set of free energy calculations. The computational performance of the method relative to standard Monte Carlo simulation is also discussed.

  10. Two-dimensional radiative transfer in cloudy atmospheres - The spherical harmonic spatial grid method

    NASA Technical Reports Server (NTRS)

    Evans, K. F.

    1993-01-01

    A new two-dimensional monochromatic method that computes the transfer of solar or thermal radiation through atmospheres with arbitrary optical properties is described. The model discretizes the radiative transfer equation by expanding the angular part of the radiance field in a spherical harmonic series and representing the spatial part with a discrete grid. The resulting sparse coupled system of equations is solved iteratively with the conjugate gradient method. A Monte Carlo model is used for extensive verification of outgoing flux and radiance values from both smooth and highly variable (multifractal) media. The spherical harmonic expansion naturally allows for different levels of approximation, but tests show that the 2D equivalent of the two-stream approximation is poor at approximating variations in the outgoing flux. The model developed here is shown to be highly efficient so that media with tens of thousands of grid points can be computed in minutes. The large improvement in efficiency will permit quick, accurate radiative transfer calculations of realistic cloud fields and improve our understanding of the effect of inhomogeneity on radiative transfer in cloudy atmospheres.

  11. Convergence of Godunov type methods for a conservation law with a spatially varying discontinuous flux function

    NASA Astrophysics Data System (ADS)

    Adimurthi; Mishra, Siddhartha; Gowda, G. D. Veerappa

    2007-09-01

    We deal with single conservation laws with a spatially varying and possibly discontinuous coefficient. This equation includes as a special case single conservation laws with conservative and possibly singular source terms. We extend the framework of optimal entropy solutions for these classes of equations based on a two-step approach. In the first step, an interface connection vector is used to define infinite classes of entropy solutions. We show that each of these classes of solutions is stable in L^1 . This allows for the possibility of choosing one of these classes of solutions based on the physics of the problem. In the second step, we define optimal entropy solutions based on the solution of a certain optimization problem at the discontinuities of the coefficient. This method leads to optimal entropy solutions that are consistent with physically observed solutions in two-phase flows in heterogeneous porous media. Another central aim of this paper is to develop suitable numerical schemes for these equations. We develop and analyze a set of Godunov type finite volume methods that are based on exact solutions of the corresponding Riemann problem. Numerical experiments are shown comparing the performance of these schemes on a set of test problems.

  12. Determination of the spatial characteristics of an RF electrodeless discharge by the method of emission tomography

    SciTech Connect

    Denisova, N. V.; Revalde, G.; Skudra, A.

    2006-11-15

    The spatial distribution of the density of mercury atoms in the 7{sup 3}S state in a spherical RF electrode-less gas-discharge lamp is reconstructed by the method of emission tomography. The local values of the corresponding emission coefficients, which are proportional to the density of mercury atoms in the 7{sup 3}S state, are determined from integral (over the plasma volume) measurements of the lamp radiation at a wavelength of 546.1 nm with the help of an algorithm based on the maximum entropy method. The results obtained show that, for all of the operating modes under study, the profile of the density of mercury atoms in the 7{sup 3}S state has a minimum in the center of the lamp and a maximum near its wall. At a generator current of 100 mA and cold-spot temperature of 41 deg. C, the density of mercury atoms in the 7{sup 3}S state is observed to drop substantially both in the center of the lamp and near its wall, the density in the center being reduced to almost zero. An explanation of this phenomenon is proposed.

  13. A Spatial Overlay Ranking Method for a Geospatial Search of Text Objects

    USGS Publications Warehouse

    Lanfear, Kenneth J.

    2006-01-01

    Earth-science researchers need the capability to find relevant information by location and topic. Conventional geographic techniques that simply check whether polygons intersect can efficiently achieve a high recall on location, but can not achieve precision for ranking results in likely order of importance to the reader. A spatial overlay ranking based upon how well an object's footprint matches the search area provides a more effective way to spatially search a collection of reports, and avoids many of the problems associated with an 'in/out' (True/False) boolean search. Moreover, spatial overlay ranking appears to work well even when spatial extent is defined only by a simple bounding box.

  14. Elevated waterproof access floor system and method of making the same

    NASA Technical Reports Server (NTRS)

    Cohen, Marc M. (Inventor)

    1987-01-01

    An elevated waterproof access floor system having subfloor channels or compartments for power lines, gas lines or the like is adapted such that it can be opened and subsequently resealed without destroying the waterproofing and without destroying its aesthetic appearance. A multiplicity of tiles are supported on a support grid, and a flooring sheet is supported on the tiles. Attachment means are provided to prevent lateral but not vertical movement of the flooring sheet with respect to the tiles so that the flooring sheet can be lifted off the tiles, but when the flooring sheet is supported on the tiles, no lateral slipping will occur. The flooring sheet is made of a heat resealable material, so that it can be cut away in sections, and the tiles therebelow lifted off, to provide access to subfloor compartments.

  15. Water accessibility in a membrane-inserting peptide comparing Overhauser DNP and pulse EPR methods

    NASA Astrophysics Data System (ADS)

    Segawa, Takuya F.; Doppelbauer, Maximilian; Garbuio, Luca; Doll, Andrin; Polyhach, Yevhen O.; Jeschke, Gunnar

    2016-05-01

    Water accessibility is a key parameter for the understanding of the structure of biomolecules, especially membrane proteins. Several experimental techniques based on the combination of electron paramagnetic resonance (EPR) spectroscopy with site-directed spin labeling are currently available. Among those, we compare relaxation time measurements and electron spin echo envelope modulation (ESEEM) experiments using pulse EPR with Overhauser dynamic nuclear polarization (DNP) at X-band frequency and a magnetic field of 0.33 T. Overhauser DNP transfers the electron spin polarization to nuclear spins via cross-relaxation. The change in the intensity of the 1H NMR spectrum of H2O at a Larmor frequency of 14 MHz under a continuous-wave microwave irradiation of the nitroxide spin label contains information on the water accessibility of the labeled site. As a model system for a membrane protein, we use the hydrophobic α-helical peptide WALP23 in unilamellar liposomes of DOPC. Water accessibility measurements with all techniques are conducted for eight peptides with different spin label positions and low radical concentrations (10-20 μM). Consistently in all experiments, the water accessibility appears to be very low, even for labels positioned near the end of the helix. The best profile is obtained by Overhauser DNP, which is the only technique that succeeds in discriminating neighboring positions in WALP23. Since the concentration of the spin-labeled peptides varied, we normalized the DNP parameter ɛ, being the relative change of the NMR intensity, by the electron spin concentration, which was determined from a continuous-wave EPR spectrum.

  16. Water accessibility in a membrane-inserting peptide comparing Overhauser DNP and pulse EPR methods.

    PubMed

    Segawa, Takuya F; Doppelbauer, Maximilian; Garbuio, Luca; Doll, Andrin; Polyhach, Yevhen O; Jeschke, Gunnar

    2016-05-21

    Water accessibility is a key parameter for the understanding of the structure of biomolecules, especially membrane proteins. Several experimental techniques based on the combination of electron paramagnetic resonance (EPR) spectroscopy with site-directed spin labeling are currently available. Among those, we compare relaxation time measurements and electron spin echo envelope modulation (ESEEM) experiments using pulse EPR with Overhauser dynamic nuclear polarization (DNP) at X-band frequency and a magnetic field of 0.33 T. Overhauser DNP transfers the electron spin polarization to nuclear spins via cross-relaxation. The change in the intensity of the (1)H NMR spectrum of H2O at a Larmor frequency of 14 MHz under a continuous-wave microwave irradiation of the nitroxide spin label contains information on the water accessibility of the labeled site. As a model system for a membrane protein, we use the hydrophobic α-helical peptide WALP23 in unilamellar liposomes of DOPC. Water accessibility measurements with all techniques are conducted for eight peptides with different spin label positions and low radical concentrations (10-20 μM). Consistently in all experiments, the water accessibility appears to be very low, even for labels positioned near the end of the helix. The best profile is obtained by Overhauser DNP, which is the only technique that succeeds in discriminating neighboring positions in WALP23. Since the concentration of the spin-labeled peptides varied, we normalized the DNP parameter ϵ, being the relative change of the NMR intensity, by the electron spin concentration, which was determined from a continuous-wave EPR spectrum. PMID:27208942

  17. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks.

    PubMed

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Zhang, Xuekun

    2015-01-01

    Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks. PMID:26633421

  18. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks

    PubMed Central

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Zhang, Xuekun

    2015-01-01

    Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95% of the theoretical optimal throughput and 0.97 of fairness index especially in dynamic and dense networks. PMID:26633421

  19. Multi-instrument Method to Map Spatial and Temporal Patterns of Snowmelt Infiltration

    NASA Astrophysics Data System (ADS)

    Hyde, K.; Beverly, D.; Thayer, D.; Speckman, H. N.; Parsekian, A.; Kelleners, T.

    2015-12-01

    Mapping spatial patterns of relative soil moisture over time may improve understanding of snowmelt infiltration processes in heterogeneous systems. Conventional soil water measurement methods disturb soil properties and rocky materials generally limit installation of monitoring instruments to shallow depths in mountainous landscapes with snowmelt dominated hydrology. Modifications to existing technology combined with low impact installation methods provide high temporal and spatial resolution of relative soil moisture as well as a temperature profile and water table level. Closely spaced (10cm) electrical resistance pads are combined in a small diameter (2.54 cm) tube with temperature probes each 50cm, a pressure transducer, and a tube to extract groundwater for stable isotope analysis. This vertical probe array (VPA) extends 3.2m and is installed in a small diameter (4 cm) bore using a backpack drill limiting soil disturbance. Two VPAs are installed in the Snowy Range of Wyoming, one in a forested mountainous environment impacted by mortality by insects and disease and the other (limited to resistance pads only) in recently burned sagelands. Each VPA is co-located with meteorological stations. Eddy-covariance, sap flux, electrical resistivity, snowpack survey, and other hillslope eco-hydrology measurements accompany the fully instrumented VPA. Data are sampled and recorded at 5 or 15 minute intervals starting in December 2014. Over the winter both sites exhibit highly variable patterns of relatively dry soils with steady increase in wetness. Abrupt increases in relative wetness occurred with short periods of warming temperatures in Spring. Following a temperature increase in the forested site the relative moisture dramatically increased over a period of several hours at all depths as water level rose 1m within 8 hours. In contrast, following snowmelt relative moisture in the sageland site increased gradually and systematically with depth over a period of two weeks

  20. A quantitative method for zoning of protected areas and its spatial ecological implications.

    PubMed

    Del Carmen Sabatini, María; Verdiell, Adriana; Rodríguez Iglesias, Ricardo M; Vidal, Marta

    2007-04-01

    Zoning is a key prescriptive tool for administration and management of protected areas. However, the lack of zoning is common for most protected areas in developing countries and, as a consequence, many protected areas are not effective in achieving the goals for which they were created. In this work, we introduce a quantitative method to expeditiously zone protected areas and we evaluate its ecological implications on hypothetical zoning cases. A real-world application is reported for the Talampaya National Park, a UNESCO World Heritage Site located in Argentina. Our method is a modification of the zoning forest model developed by Bos [Bos, J., 1993. Zoning in forest management: a quadratic assignment problem solved by simulated annealing. Journal of Environmental Management 37, 127-145.]. Main innovations involve a quadratic function of distance between land units, non-reciprocal weights for adjacent land uses (mathematically represented by a non-symmetric matrix), and the possibility of imposing a connectivity constraint. Due to its intrinsic spatial dimension, the zoning problem belongs to the NP-hard class, i.e. a solution can only be obtained in non-polynomial time [Nemhausser, G., Wolsey, L., 1988. Integer and Combinatorial Optimization. John Wiley, New York.]. For that purpose, we applied a simulated annealing heuristic implemented as a FORTRAN language routine. Our innovations were effective in achieving zoning designs more compatible with biological diversity protection. The quadratic distance term facilitated the delineation of core zones for elements of significance; the connectivity constraint minimized fragmentation; non-reciprocal land use weightings contributed to better representing management decisions, and influenced mainly the edge and shape of zones. This quantitative method can assist the zoning process within protected areas by offering many zonation scheme alternatives with minimum cost, time and effort. This ability provides a new tool to

  1. Drug-Related Arrest Rates and Spatial Access to Syringe Exchange Programs in New York City Health Districts: Combined Effects on the Risk of Injection-Related Infections among Injectors

    PubMed Central

    Jarlais, Don C Des; Tempalski, Barbara; Bossak, Brian H; Ross, Zev; Friedman, Samuel R

    2011-01-01

    Drug-related law enforcement activities may undermine the protective effects of syringe exchange programs (SEPs) on local injectors’ risk of injection-related infections. We explored the spatial overlap of drug-related arrest rates and access to SEPs over time (1995-2006) in New York City health districts, and used multilevel models to investigate the relationship of these two district-level exposures to the odds of injecting with an unsterile syringe. Districts with better SEP access had higher arrest rates, and arrest rates undermined SEPs’ protective relationship with unsterile injecting. Drug-related enforcement strategies targeting drug users should be de-emphasized in areas surrounding SEPs. PMID:22047790

  2. A new method for spatial resolution enhancement of hyperspectral images using sparse coding and linear spectral unmixing

    NASA Astrophysics Data System (ADS)

    Hashemi, Nezhad Z.; Karami, A.

    2015-10-01

    Hyperspectral images (HSI) have high spectral and low spatial resolutions. However, multispectral images (MSI) usually have low spectral and high spatial resolutions. In various applications HSI with high spectral and spatial resolutions are required. In this paper, a new method for spatial resolution enhancement of HSI using high resolution MSI based on sparse coding and linear spectral unmixing (SCLSU) is introduced. In the proposed method (SCLSU), high spectral resolution features of HSI and high spatial resolution features of MSI are fused. In this case, the sparse representation of some high resolution MSI and linear spectral unmixing (LSU) model of HSI and MSI is simultaneously used in order to construct high resolution HSI (HRHSI). The fusion process of HSI and MSI is formulated as an ill-posed inverse problem. It is solved by the Split Augmented Lagrangian Shrinkage Algorithm (SALSA) and an orthogonal matching pursuit (OMP) algorithm. Finally, the proposed algorithm is applied to the Hyperion and ALI datasets. Compared with the other state-of-the-art algorithms such as Coupled Nonnegative Matrix Factorization (CNMF) and local spectral unmixing, the SCLSU has significantly increased the spatial resolution and in addition the spectral content of HSI is well maintained.

  3. An Accessible Method for Implementing Hierarchical Models with Spatio-Temporal Abundance Data

    PubMed Central

    Ross, Beth E.; Hooten, Mevin B.; Koons, David N.

    2012-01-01

    A common goal in ecology and wildlife management is to determine the causes of variation in population dynamics over long periods of time and across large spatial scales. Many assumptions must nevertheless be overcome to make appropriate inference about spatio-temporal variation in population dynamics, such as autocorrelation among data points, excess zeros, and observation error in count data. To address these issues, many scientists and statisticians have recommended the use of Bayesian hierarchical models. Unfortunately, hierarchical statistical models remain somewhat difficult to use because of the necessary quantitative background needed to implement them, or because of the computational demands of using Markov Chain Monte Carlo algorithms to estimate parameters. Fortunately, new tools have recently been developed that make it more feasible for wildlife biologists to fit sophisticated hierarchical Bayesian models (i.e., Integrated Nested Laplace Approximation, ‘INLA’). We present a case study using two important game species in North America, the lesser and greater scaup, to demonstrate how INLA can be used to estimate the parameters in a hierarchical model that decouples observation error from process variation, and accounts for unknown sources of excess zeros as well as spatial and temporal dependence in the data. Ultimately, our goal was to make unbiased inference about spatial variation in population trends over time. PMID:23166658

  4. An Accessible Method for Implementing Hierarchical Models with Spatio-Temporal Abundance Data

    USGS Publications Warehouse

    Ross, Beth E.; Hooten, Melvin B.; Koons, David N.

    2012-01-01

    A common goal in ecology and wildlife management is to determine the causes of variation in population dynamics over long periods of time and across large spatial scales. Many assumptions must nevertheless be overcome to make appropriate inference about spatio-temporal variation in population dynamics, such as autocorrelation among data points, excess zeros, and observation error in count data. To address these issues, many scientists and statisticians have recommended the use of Bayesian hierarchical models. Unfortunately, hierarchical statistical models remain somewhat difficult to use because of the necessary quantitative background needed to implement them, or because of the computational demands of using Markov Chain Monte Carlo algorithms to estimate parameters. Fortunately, new tools have recently been developed that make it more feasible for wildlife biologists to fit sophisticated hierarchical Bayesian models (i.e., Integrated Nested Laplace Approximation, ‘INLA’). We present a case study using two important game species in North America, the lesser and greater scaup, to demonstrate how INLA can be used to estimate the parameters in a hierarchical model that decouples observation error from process variation, and accounts for unknown sources of excess zeros as well as spatial and temporal dependence in the data. Ultimately, our goal was to make unbiased inference about spatial variation in population trends over time.

  5. New method for generating breast models featuring glandular tissue spatial distribution

    NASA Astrophysics Data System (ADS)

    Paixão, L.; Oliveira, B. B.; Oliveira, M. A.; Teixeira, M. H. A.; Fonseca, T. C. F.; Nogueira, M. S.

    2016-02-01

    Mammography is the main radiographic technique used for breast imaging. A major concern with mammographic imaging is the risk of radiation-induced breast cancer due to the high sensitivity of breast tissue. The mean glandular dose (DG) is the dosimetric quantity widely accepted to characterize the risk of radiation induced cancer. Previous studies have concluded that DG depends not only on the breast glandular content but also on the spatial distribution of glandular tissue within the breast. In this work, a new method for generating computational breast models featuring skin composition and glandular tissue distribution from patients undergoing digital mammography is proposed. Such models allow a more accurate way of calculating individualized breast glandular doses taking into consideration the glandular tissue fraction. Sixteen breast models of four patients with different glandularity breasts were simulated and the results were compared with those obtained from recommended DG conversion factors. The results show that the internationally recommended conversion factors may be overestimating the mean glandular dose to less dense breasts and underestimating the mean glandular dose for denser breasts. The methodology described in this work constitutes a powerful tool for breast dosimetry, especially for risk studies.

  6. Methods used to parameterize the spatially-explicit components of a state-and-transition simulation model

    USGS Publications Warehouse

    Sleeter, Rachel; Acevedo, William; Soulard, Christopher E.; Sleeter, Benjamin M.

    2015-01-01

    Spatially-explicit state-and-transition simulation models of land use and land cover (LULC) increase our ability to assess regional landscape characteristics and associated carbon dynamics across multiple scenarios. By characterizing appropriate spatial attributes such as forest age and land-use distribution, a state-and-transition model can more effectively simulate the pattern and spread of LULC changes. This manuscript describes the methods and input parameters of the Land Use and Carbon Scenario Simulator (LUCAS), a customized state-and-transition simulation model utilized to assess the relative impacts of LULC on carbon stocks for the conterminous U.S. The methods and input parameters are spatially explicit and describe initial conditions (strata, state classes and forest age), spatial multipliers, and carbon stock density. Initial conditions were derived from harmonization of multi-temporal data characterizing changes in land use as well as land cover. Harmonization combines numerous national-level datasets through a cell-based data fusion process to generate maps of primary LULC categories. Forest age was parameterized using data from the North American Carbon Program and spatially-explicit maps showing the locations of past disturbances (i.e. wildfire and harvest). Spatial multipliers were developed to spatially constrain the location of future LULC transitions. Based on distance-decay theory, maps were generated to guide the placement of changes related to forest harvest, agricultural intensification/extensification, and urbanization. We analyze the spatially-explicit input parameters with a sensitivity analysis, by showing how LUCAS responds to variations in the model input. This manuscript uses Mediterranean California as a regional subset to highlight local to regional aspects of land change, which demonstrates the utility of LUCAS at many scales and applications.

  7. A method for protecting and controlling access to JPEG2000 images

    NASA Astrophysics Data System (ADS)

    Serrão, Carlos; Serra, Antonio; Fonseca, Pedro; Salles Dias, Jose M.

    2003-11-01

    The image compression standard JPEG2000 brings not only powerful compression performance but also new functionality unavailable in previous standards (such as region of interest, scalability and random access to image data, through flexible code stream description of the image). ISO/IEC JTC1/SC29/WG1, which is the ISO Committee working group for JPEG2000 standardization is currently defining additional parts to the standard that will allow extended functionalities. One of these extensions is Part 8 JPSEC - JPEG2000 security, which deals with the protection and access control of JPEG2000 code-stream. This paper reports the JPSEC activities detailing with the three core experiments which are in progress to supply the JPEG2000 ISO Committee, with the appropriate protection technology. These core experiments are focusing on the protection of the code-stream itself and on the overall security infrastructure that is needed to manage the access rights of users and applications to that protected code-stream. Regarding the encryption/scrambling process, this one deals with the JPEG2000 code stream in such a way that only the packets, which contain image data information are encrypted. All the other code-stream data will be in clear mode. This paper will also advance details of one of the JPSEC proposed solutions for the security infrastructure - OpenSDRM (Open and Secure Digital Rights Management), which provides security and rights management from the content provider to the content final user. A use case where this security infrastructure was successfully used will also be provided.

  8. An Introductory Mixed-Methods Intersectionality Analysis of College Access and Equity: An Examination of First-Generation Asian Americans and Pacific Islanders

    ERIC Educational Resources Information Center

    Museus, Samuel D.

    2011-01-01

    In this article, the author discusses how researchers can use mixed-methods approaches and intersectional analyses to understand college access among first-generation Asian American and Pacific Islanders (AAPIs). First, he discusses the utility of mixed-methods approaches and intersectionality research in studying college access. Then, he…

  9. Method to Enhance the Operation of an Optical Inspection Instrument Using Spatial Light Modulators

    NASA Technical Reports Server (NTRS)

    Trolinger, James; Lal, Amit; Jo, Joshua; Kupiec, Stephen

    2012-01-01

    For many aspheric and freeform optical components, existing interferometric solutions require a custom computer-generated hologram (CGH) to characterize the part. The overall objective of this research is to develop hardware and a procedure to produce a combined, dynamic, Hartmann/ Digital Holographic interferometry inspection system for a wide range of advanced optical components, including aspheric and freeform optics. This new instrument would have greater versatility and dynamic range than currently available measurement systems. The method uses a spatial light modulator to pre-condition wavefronts for imaging, interferometry, and data processing to improve the resolution and versatility of an optical inspection instrument. Existing interferometers and Hartmann inspection systems have either too small a dynamic range or insufficient resolution to characterize conveniently unusual optical surfaces like aspherical and freeform optics. For interferometers, a specially produced, computer-generated holographic optical element is needed to transform the wavefront to within the range of the interferometer. A new hybrid wavefront sensor employs newly available spatial light modulators (SLMs) as programmable holographic optical elements (HOEs). The HOE is programmed to enable the same instrument to inspect an optical element in stages, first by a Hartmann measurement, which has a very large dynamic range but less resolution. The first measurement provides the information required to precondition a reference wave that avails the measurement process to the more precise phase shifting interferometry. The SLM preconditions a wavefront before it is used to inspect an optical component. This adds important features to an optical inspection system, enabling not just wavefront conditioning for null testing and dynamic range extension, but also the creation of hybrid measurement procedures. This, for example, allows the combination of dynamic digital holography and Hartmann

  10. New developments in spatial interpolation methods of Sea-Level Anomalies in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Troupin, Charles; Barth, Alexander; Beckers, Jean-Marie; Pascual, Ananda

    2014-05-01

    The gridding of along-track Sea-Level Anomalies (SLA) measured by a constellation of satellites has numerous applications in oceanography, such as model validation, data assimilation or eddy tracking. Optimal Interpolation (OI) is often the preferred method for this task, as it leads to the lowest expected error and provides an error field associated to the analysed field. However, the numerical cost of the method may limit its utilization in situations where the number of data points is significant. Furthermore, the separation of non-adjacent regions with OI requires adaptation of the code, leading to a further increase of the numerical cost. To solve these issues, the Data-Interpolating Variational Analysis (DIVA), a technique designed to produce gridded from sparse in situ measurements, is applied on SLA data in the Mediterranean Sea. DIVA and OI have been shown to be equivalent (provided some assumptions on the covariances are made). The main difference lies in the covariance function, which is not explicitly formulated in DIVA. The particular spatial and temporal distributions of measurements required adaptation in the Software tool (data format, parameter determinations, ...). These adaptation are presented in the poster. The daily analysed and error fields obtained with this technique are compared with available products such as the gridded field from the Archiving, Validation and Interpretation of Satellite Oceanographic data (AVISO) data server. The comparison reveals an overall good agreement between the products. The time evolution of the mean error field evidences the need of a large number of simultaneous altimetry satellites: in period during which 4 satellites are available, the mean error is on the order of 17.5%, while when only 2 satellites are available, the error exceeds 25%. Finally, we propose the use sea currents to improve the results of the interpolation, especially in the coastal area. These currents can be constructed from the bathymetry

  11. Spatial requirements of poultry assessed by using a colour-contrast method (KobaPlan).

    PubMed

    Spindler, B; Giersberg, M F; Briese, A; Kemper, N; Hartung, J

    2016-01-01

    Sufficient floor space is a fundamental precondition for poultry to perform normal behavioural patterns. To calculate and determine stocking densities, it is essential to know the absolute minimum surface area required by any given animal (body space). Additional space is required for characteristic behaviours (behavioural space) and for adequate inter-individual distances, group sizes and room to perform social interactions have to be taken into account. To calculate body space, planimetric measurements were carried out by the colour contrast method "KobaPlan" in various poultry species in standing and sitting positions and at a number of different ages. They included laying hens (Lohmann brown (LB), Lohmann selected Leghorn (LSL)), broiler breeders (Ross, both genders), broiler chickens (Ross 308, both genders), turkeys (BUT 6, males), Peking ducks (Cherry Valley, both genders) and Muscovy ducks (Canedins R51, males). Depending on live weight, age, plumage condition and body position, LB hens occupied an average area between 401 cm(2) and 542 cm(2), LSL hens between 353 cm(2) and 445 cm(2), broiler breeder females between 440 cm(2) and 537 cm(2), broiler breeder males 623 cm(2) up to 945 cm(2), broiler chickens up to 434 cm(2), male fattening turkeys up to 1808 cm(2), Muscovy drakes up to 873 cm(2) and Peking ducks up to 627 cm(2). The values can be regarded as necessary minimum spatial requirements for the measured poultry species and genotype. The current method offers the potential to record the area occupied by animals exhibiting species-specific behavioural patterns. PMID:26654762

  12. [Comparison on the methods for spatial interpolation of the annual average precipitation in the Loess Plateau region].

    PubMed

    Yu, Yang; Wei, Wei; Chen, Li-ding; Yang, Lei; Zhang, Han-dan

    2015-04-01

    Based on 57 years (1957-2013) daily precipitation datasets of the 85 meteorological stations in the Loess Plateau region, different spatial interpolation methods, including ordinary kriging (OK), inverse distance weighting (IDW) and radial-based function (RBF), were conducted to analyze the spatial variation of annual average precipitation regionally. Meanwhile, the mean absolute error (MAE), the root mean square error (RMSE), the accuracy (AC) and the Pearson correlation coefficient (R) were compared among the interpolation results in order to quantify the effects of different interpolation methods on spatial variation of the annual average precipitation. The results showed that the Moran's I index was 0.67 for the 57 years annual average precipitation in the Loess Plateau region. Meteorological stations exhibited strong spatial correlation. The validation results of the 63 training stations and 22 test stations indicated that there were significant correlations between the training and test values among different interpolation methods. However, the RMSE (IDW = 51.49, RBF = 43.79) and MAE (IDW = 38.98, RBF = 34.61) of the IDW and the RBF showed higher values than the OK. In addition, the comparison of the four semi-variagram models (Circular, Spherical, Exponential and Gaussian) for the OK indicated that the circular model had the lowest MAE (32.34) and the highest accuracy (0.976), while the MAE of the exponential model was the highest (33.24). In conclusion, comparing the validation between the training data and test results of the different spatial interpolation methods, the circular model of the OK method was the best one for obtaining accurate spatial interpolation of annual average precipitation in the Loess Plateau region. PMID:26259439

  13. The Versatility of SpAM: A Fast, Efficient, Spatial Method of Data Collection for Multidimensional Scaling

    PubMed Central

    Hout, Michael C.; Goldinger, Stephen D.; Ferguson, Ryan W.

    2012-01-01

    Although traditional methods to collect similarity data (for multidimensional scaling, MDS) are robust, they share a key shortcoming. Specifically, the possible pairwise comparisons in any set of objects grow rapidly as a function of set size. This leads to lengthy experimental protocols, or procedures that involve scaling stimulus subsets. We review existing methods of collecting similarity data, and critically examine a spatial arrangement method (SpAM) proposed by Goldstone (1994a), in which similarity ratings are obtained by presenting many stimuli at once. The participant moves stimuli around the computer screen, placing them at distances from one another that are proportional to subjective similarity. This provides a fast, efficient, and user-friendly method for obtaining MDS spaces. Participants gave similarity ratings to artificially constructed visual stimuli (comprising 2–3 perceptual dimensions), and non-visual stimuli (animal names) with less-defined underlying dimensions. Ratings were obtained using four methods: pairwise comparisons, spatial arrangement, and two novel hybrid methods. We compared solutions from alternative methods to the pairwise method, finding that the SpAM produces high-quality MDS solutions. Monte Carlo simulations on degraded data suggest that the method is also robust to reductions in sample sizes and granularity. Moreover, coordinates derived from SpAM solutions accurately predicted discrimination among objects in “same/different” classification. In the General Discussion, we address the benefits of using a spatial medium to collect similarity measures. PMID:22746700

  14. The versatility of SpAM: a fast, efficient, spatial method of data collection for multidimensional scaling.

    PubMed

    Hout, Michael C; Goldinger, Stephen D; Ferguson, Ryan W

    2013-02-01

    Although traditional methods to collect similarity data (for multidimensional scaling [MDS]) are robust, they share a key shortcoming. Specifically, the possible pairwise comparisons in any set of objects grow rapidly as a function of set size. This leads to lengthy experimental protocols, or procedures that involve scaling stimulus subsets. We review existing methods of collecting similarity data, and critically examine the spatial arrangement method (SpAM) proposed by Goldstone (1994a), in which similarity ratings are obtained by presenting many stimuli at once. The participant moves stimuli around the computer screen, placing them at distances from one another that are proportional to subjective similarity. This provides a fast, efficient, and user-friendly method for obtaining MDS spaces. Participants gave similarity ratings to artificially constructed visual stimuli (comprising 2-3 perceptual dimensions) and nonvisual stimuli (animal names) with less-defined underlying dimensions. Ratings were obtained with 4 methods: pairwise comparisons, spatial arrangement, and 2 novel hybrid methods. We compared solutions from alternative methods to the pairwise method, finding that the SpAM produces high-quality MDS solutions. Monte Carlo simulations on degraded data suggest that the method is also robust to reductions in sample sizes and granularity. Moreover, coordinates derived from SpAM solutions accurately predicted discrimination among objects in same-different classification. We address the benefits of using a spatial medium to collect similarity measures. PMID:22746700

  15. A Bayesian method to mine spatial data sets to evaluate the vulnerability of human beings to catastrophic risk.

    PubMed

    Li, Lianfa; Wang, Jinfeng; Leung, Hareton; Zhao, Sisi

    2012-06-01

    Vulnerability of human beings exposed to a catastrophic disaster is affected by multiple factors that include hazard intensity, environment, and individual characteristics. The traditional approach to vulnerability assessment, based on the aggregate-area method and unsupervised learning, cannot incorporate spatial information; thus, vulnerability can be only roughly assessed. In this article, we propose Bayesian network (BN) and spatial analysis techniques to mine spatial data sets to evaluate the vulnerability of human beings. In our approach, spatial analysis is leveraged to preprocess the data; for example, kernel density analysis (KDA) and accumulative road cost surface modeling (ARCSM) are employed to quantify the influence of geofeatures on vulnerability and relate such influence to spatial distance. The knowledge- and data-based BN provides a consistent platform to integrate a variety of factors, including those extracted by KDA and ARCSM to model vulnerability uncertainty. We also consider the model's uncertainty and use the Bayesian model average and Occam's Window to average the multiple models obtained by our approach to robust prediction of the risk and vulnerability. We compare our approach with other probabilistic models in the case study of seismic risk and conclude that our approach is a good means to mining spatial data sets for evaluating vulnerability. PMID:22404550

  16. REVIEW OF SIMULATION METHODS FOR SPATIALLY-EXPLICIT POPULATION-LEVEL RISK ASSESSMENT

    EPA Science Inventory

    Factors that significantly impact population dynamics, such as resource availability and exposure to stressors, frequently vary over space and thereby determine the heterogeneous spatial distributions of organisms. Considering this fact, the US Environmental Protection Agency's ...

  17. Toward safe accessibility of opioid pain medicines in Vietnam and other developing countries: a balanced policy method.

    PubMed

    Krakauer, Eric L; Nguyen, Thi Phuong Cham; Husain, Syeda Asra; Nguyen, Thi Hai Yen; Joranson, David E; Luong, Ngoc Khue; Maurer, Martha A

    2015-05-01

    Moderate or severe pain is common among people with advanced cancer and other life-threatening illnesses. Yet despite agreement that pain relief is a human right, the poorest 80% of the world's population rarely have access to strong opioid analgesics. Excessively restrictive opioid policies, especially in developing countries, both stem from and propagate misguided fears about opioids, so-called opiophobia. Because opiophobia, like any norm, is historically, socially, and culturally situated, efforts to change opiophobic policies will be most effective if guided by awareness of their historical, social, and cultural determinants. We describe some of these determinants in Vietnam and report on results of an ongoing project there to allay opiophobia and improve safe access to opioids for medical uses. We used a method that entails working with committed local partners, including a high-level official from the Ministry of Health, to review all Vietnamese policies governing opioid accessibility to identify the barriers; devising an action plan to safely reduce or circumnavigate the barriers; obtaining buy-in for the plan from all stakeholders, including drug regulators and the police; and assisting the Ministry of Health to implement the plan. Since the start of the project, morphine consumption has increased each year and as of 2010 was ninefold greater than in 2003, and the number of hospitals offering palliative care has increased from three to 15. We conclude that this balanced policy method appears to be helping to reduce barriers to opioid access in Vietnam and should be used in other developing countries. PMID:25523889

  18. [Study of access to health care and drugs in Cameroon: 1. Methods and validation].

    PubMed

    Commeyras, Christophe; Ndo, Jean Rolin; Merabet, Omar; Koné, Hamidou; Rakotondrabé, Faraniaina Patricia

    2005-01-01

    During the 1980s, an economic depression and the concomitant decrease in the national health budget modified the population's health behavior. Improvement of the economy since the late 1990s makes it possible to renew the national health policy. To prepare the highly indebted and poor countries' program (HIPC), the Minister of Health and its partners commissioned a survey to measure the population's real access to health care and the factors that determine this accessibility and to propose concrete corrective actions. To fulfill these objectives, the steering committee decided to analyze health care demand, through a national population survey, and supply capacity, through a national survey of pharmacies and other drug dispensers. A survey of persons using medications will also be conducted (Fig.1). Focusing on this component of health care is justified by these findings: 95% of persons feeling ill buy drugs, whereas only 31% consult a physician or other healthcare provider, and half of the average household's health expenditures are for drugs. Financial, geographic, social and quality indicators were defined to measure accessibility and its determining factors (Table 1). The smallest administrative unit, the health area (HA), was chosen as the sampling unit, to enable us to survey together healthcare demand, supply and consumption according to different concentrations of supply and demand . It behaves as a cluster of sampling units of different populations: drug retailers of all sectors, drug users, households, and ill persons within the households. The HA samples include Yaounde and Douala, with urban and rural sub-samples, for which sampling ratios increase with the diversity of supply and demand, according to several pre-defined factors. The study includes 400 HAs, covering more than one third of the population (Table 2). Within these HAs, 900 pharmacies and other formal drug retailers, 709 street vendors, 4,505 households, 2,532 ill persons in these households

  19. Illuminant estimation for color constancy: why spatial-domain methods work and the role of the color distribution.

    PubMed

    Cheng, Dongliang; Prasad, Dilip K; Brown, Michael S

    2014-05-01

    Color constancy is a well-studied topic in color vision. Methods are generally categorized as (1) low-level statistical methods, (2) gamut-based methods, and (3) learning-based methods. In this work, we distinguish methods depending on whether they work directly from color values (i.e., color domain) or from values obtained from the image's spatial information (e.g., image gradients/frequencies). We show that spatial information does not provide any additional information that cannot be obtained directly from the color distribution and that the indirect aim of spatial-domain methods is to obtain large color differences for estimating the illumination direction. This finding allows us to develop a simple and efficient illumination estimation method that chooses bright and dark pixels using a projection distance in the color distribution and then applies principal component analysis to estimate the illumination direction. Our method gives state-of-the-art results on existing public color constancy datasets as well as on our newly collected dataset (NUS dataset) containing 1736 images from eight different high-end consumer cameras. PMID:24979637

  20. ThermoBuild: Online Method Made Available for Accessing NASA Glenn Thermodynamic Data

    NASA Technical Reports Server (NTRS)

    McBride, Bonnie; Zehe, Michael J.

    2004-01-01

    The new Web site program "ThermoBuild" allows users to easily access and use the NASA Glenn Thermodynamic Database of over 2000 solid, liquid, and gaseous species. A convenient periodic table allows users to "build" the molecules of interest and designate the temperature range over which thermodynamic functions are to be displayed. ThermoBuild also allows users to build custom databases for use with NASA's Chemical Equilibrium with Applications (CEA) program or other programs that require the NASA format for thermodynamic properties. The NASA Glenn Research Center has long been a leader in the compilation and dissemination of up-to-date thermodynamic data, primarily for use with the NASA CEA program, but increasingly for use with other computer programs.

  1. Methods for Generating Year-Round Access to Amphioxus in the Laboratory

    PubMed Central

    Benito-Gutiérrez, Èlia; Weber, Hermann; Bryant, Diana Virginia; Arendt, Detlev

    2013-01-01

    Cephalochordates, commonly known as amphioxus, are key to understanding vertebrate origins. However, laboratory work suffers from limited access to adults and embryonic material. Here we report the design and experimental validation of an inland marine facility that allows establishing stable amphioxus colonies in the laboratory and obtaining embryos at any time of day and over almost the entire year, far exceeding natural conditions. This is achieved by mimicking the natural benthic environment, natural day- and moon- light, natural substrate and by providing a strictly controlled and seasonally fluctuating temperature regimen. Moreover, supplemented algae diets allow animals to refill their gonads in consecutive years. Spontaneous spawning, a major problem in previous setups, no longer occurs in our facility; instead, all breeding is induced and fertilization occurs fully in vitro. Our system makes amphioxus a standard laboratory animal model. PMID:23990962

  2. Methods for generating year-round access to amphioxus in the laboratory.

    PubMed

    Benito-Gutiérrez, Elia; Weber, Hermann; Bryant, Diana Virginia; Arendt, Detlev

    2013-01-01

    Cephalochordates, commonly known as amphioxus, are key to understanding vertebrate origins. However, laboratory work suffers from limited access to adults and embryonic material. Here we report the design and experimental validation of an inland marine facility that allows establishing stable amphioxus colonies in the laboratory and obtaining embryos at any time of day and over almost the entire year, far exceeding natural conditions. This is achieved by mimicking the natural benthic environment, natural day- and moon- light, natural substrate and by providing a strictly controlled and seasonally fluctuating temperature regimen. Moreover, supplemented algae diets allow animals to refill their gonads in consecutive years. Spontaneous spawning, a major problem in previous setups, no longer occurs in our facility; instead, all breeding is induced and fertilization occurs fully in vitro. Our system makes amphioxus a standard laboratory animal model. PMID:23990962

  3. Method of preliminary localization of the iris in biometric access control systems

    NASA Astrophysics Data System (ADS)

    Minacova, N.; Petrov, I.

    2015-10-01

    This paper presents a method of preliminary localization of the iris, based on the stable brightness features of the iris in images of the eye. In tests on images of eyes from publicly available databases method showed good accuracy and speed compared to existing methods preliminary localization.

  4. Utilization of a liquid crystal spatial light modulator in a gray scale detour phase method for Fourier holograms.

    PubMed

    Makey, Ghaith; El-Daher, Moustafa Sayem; Al-Shufi, Kanj

    2012-11-10

    This paper introduces a new modification for the well-known binary detour phase method, which is largely used to represent Fourier holograms; the modification utilizes gray scale level control provided by a liquid crystal spatial light modulator to improve the traditional binary detour phase. Results are shown by both simulation and experiment. PMID:23142903

  5. The Use of the Three-Dimensional Image in the Museum — The Consideration about the Spatial Imaging Methods

    NASA Astrophysics Data System (ADS)

    Ishikawa, Jun

    An exhibition is the leading role at the museum, and the three-dimensional image takes a role to deepen understanding to the exhibition contents. In a three-dimensional image, spatial imaging methods are equal to this purpose well and enable a showpiece and the seamless fusion of the image.

  6. A novel method for discovering local spatial clusters of genomic regions with functional relationships from DNA contact maps

    PubMed Central

    Hu, Xihao; Shi, Christina Huan; Yip, Kevin Y.

    2016-01-01

    Motivation: The three-dimensional structure of genomes makes it possible for genomic regions not adjacent in the primary sequence to be spatially proximal. These DNA contacts have been found to be related to various molecular activities. Previous methods for analyzing DNA contact maps obtained from Hi-C experiments have largely focused on studying individual interactions, forming spatial clusters composed of contiguous blocks of genomic locations, or classifying these clusters into general categories based on some global properties of the contact maps. Results: Here, we describe a novel computational method that can flexibly identify small clusters of spatially proximal genomic regions based on their local contact patterns. Using simulated data that highly resemble Hi-C data obtained from real genome structures, we demonstrate that our method identifies spatial clusters that are more compact than methods previously used for clustering genomic regions based on DNA contact maps. The clusters identified by our method enable us to confirm functionally related genomic regions previously reported to be spatially proximal in different species. We further show that each genomic region can be assigned a numeric affinity value that indicates its degree of participation in each local cluster, and these affinity values correlate quantitatively with DNase I hypersensitivity, gene expression, super enhancer activities and replication timing in a cell type specific manner. We also show that these cluster affinity values can precisely define boundaries of reported topologically associating domains, and further define local sub-domains within each domain. Availability and implementation: The source code of BNMF and tutorials on how to use the software to extract local clusters from contact maps are available at http://yiplab.cse.cuhk.edu.hk/bnmf/. Contact: kevinyip@cse.cuhk.edu.hk Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27307607

  7. 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

  8. [The "tunnel task": a method for examination of cognitive processes in spatial orientation performance].

    PubMed

    Schönebeck, B; Thanhäuser, J; Debus, G

    2001-01-01

    We report on the theoretical development and empirical testing of a new spatial cognition task, during which participants complete a tour through a virtual tunnel. Upon arrival they are asked to specify a "homing" vector by pointing an arrow towards the starting point of their virtual journey. Systematic experimental variations include number, length and sharpness of turns. Solving the task requires the development of a spatial representation, as alternative strategic cues (e.g., visual landmarks) are not available. Performance measures discriminate between general training effects and specific task variables. As an example, "side errors" indicate a loss of orientation and "position hits" reflect the accuracy of the spatial representation. Participants use either an egocentric or allocentric frame of reference. The task does not imply the use of egocentric vs. allocentric spatial co-ordinates, yet it allows for a reliable a-priori identification of individually preferred strategies. Our data indicate that the spatial representations formed by both groups are functionally equivalent. However, the groups differ with respect to specific patterns of orientation errors. PMID:11688148

  9. Enhancement of Spatial Understanding in AN Introductory Field Methods Project Through a Geowall Intervention

    NASA Astrophysics Data System (ADS)

    Riggs, N. R.; Kelly, M. M.

    2003-12-01

    The implementation of the GeoWall (www.geowall.org) in introductory geology labs as a visualization tool is on the increase at the undergraduate level. We report on a new project that examines how introductory field students' understanding of basic mapping skills may change after a GeoWall intervention. GLG 240 is a required field methods course for students majoring in Geology at Northern Arizona University. In this class, students learn to describe different kinds of rocks, self locate on a topographic map, use a Brunton compass, and map relatively simple geologic structures. The class is a prerequisite to upper-division classes (mineralogy, petrology, structure, etc) and is open to any student who has completed physical and historical geology. In the Fall semester 2003, we will implement the GeoWall 3D visualization technology in critical sections of GLG 240 dealing with students' perception of terrain and geologic relations. In this study we examine one of these GeoWall interventions that centers on a field exercise done on SP Crater, a young cinder cone and flow north of Flagstaff, Arizona. The goals of the exercise are an increase in student confidence in self location, a sense of how scale varies between different media (aerial photographs, topographic sheets) and distance on the ground, and an ability to follow and map contacts between Paleozoic bedrock, old and young volcanic rocks, and alluvium. This exercise has been relatively unchanged with the same instructor over the last five years. Assessment of student learning has also remained steady: rubrics were established early and applied to a student written report comprising maps, figures, and written geologic analysis. The GeoWall intervention will occur during a pre-field exercise that occurs in the laboratory. Students map contacts and describe the geologic setting of SP Crater using black and white, stereo, 1:25000 aerial photographs and mylar overlays. The intervention adds to this instruction by

  10. Image processing methods to elucidate spatial characteristics of retinal microglia after optic nerve transection.

    PubMed

    Zhang, Yudong; Peng, Bo; Wang, Shuihua; Liang, Yu-Xiang; Yang, Jiquan; So, Kwok-Fai; Yuan, Ti-Fei

    2016-01-01

    Microglia are the mononuclear phagocytes with various functions in the central nervous system, and the morphologies of microglia imply the different stages and functions. In optical nerve transection model of the retina, the retrograde degeneration of retinal ganglion cells induces microglial activations to a unique morphology termed rod microglia. A few studies described the rod microglia in the cortex and retina; however, the spatial characteristic of rod microglia is not fully understood. In this study, we built a mathematical model to characterize the spatial trait of rod microglia. In addition, we developed a Matlab-based image processing pipeline that consists of log enhancement, image segmentation, mathematical morphology based cell detection, area calculation and angle analysis. This computer program provides researchers a powerful tool to quickly analyze the spatial trait of rod microglia. PMID:26888347

  11. Image processing methods to elucidate spatial characteristics of retinal microglia after optic nerve transection

    PubMed Central

    Zhang, Yudong; Peng, Bo; Wang, Shuihua; Liang, Yu-Xiang; Yang, Jiquan; So, Kwok-Fai; Yuan, Ti-Fei

    2016-01-01

    Microglia are the mononuclear phagocytes with various functions in the central nervous system, and the morphologies of microglia imply the different stages and functions. In optical nerve transection model of the retina, the retrograde degeneration of retinal ganglion cells induces microglial activations to a unique morphology termed rod microglia. A few studies described the rod microglia in the cortex and retina; however, the spatial characteristic of rod microglia is not fully understood. In this study, we built a mathematical model to characterize the spatial trait of rod microglia. In addition, we developed a Matlab-based image processing pipeline that consists of log enhancement, image segmentation, mathematical morphology based cell detection, area calculation and angle analysis. This computer program provides researchers a powerful tool to quickly analyze the spatial trait of rod microglia. PMID:26888347

  12. Spatial accuracy of a simplified disaggregation method for traffic emissions applied in seven mid-sized Chilean cities

    NASA Astrophysics Data System (ADS)

    Ossés de Eicker, Margarita; Zah, Rainer; Triviño, Rubén; Hurni, Hans

    The spatial accuracy of top-down traffic emission inventory maps obtained with a simplified disaggregation method based on street density was assessed in seven mid-sized Chilean cities. Each top-down emission inventory map was compared against a reference, namely a more accurate bottom-up emission inventory map from the same study area. The comparison was carried out using a combination of numerical indicators and visual interpretation. Statistically significant differences were found between the seven cities with regard to the spatial accuracy of their top-down emission inventory maps. In compact cities with a simple street network and a single center, a good accuracy of the spatial distribution of emissions was achieved with correlation values>0.8 with respect to the bottom-up emission inventory of reference. In contrast, the simplified disaggregation method is not suitable for complex cities consisting of interconnected nuclei, resulting in correlation values<0.5. Although top-down disaggregation of traffic emissions generally exhibits low accuracy, the accuracy is significantly higher in compact cities and might be further improved by applying a correction factor for the city center. Therefore, the method can be used by local environmental authorities in cities with limited resources and with little knowledge on the pollution situation to get an overview on the spatial distribution of the emissions generated by traffic activities.

  13. Short communication: A method for verified access when using soft copy display.

    PubMed

    Brettle, D S; Bacon, S E

    2005-08-01

    Soft copy display is a rapidly developing area. To date, most soft copy systems can be classed by their application, e.g. review or reporting. With technology convergence this distinction is becoming less defined by the hardware and more defined by the software functionality. Although it is accepted that routine quality assurance should be conducted on soft copy monitors, this would be logistically difficult to achieve if any monitor within a hospital could be used for image review or reporting. This work proposes a simple psychophysical check to ensure optimal display performance before viewing software can be run. This is in the form of a challenge/response code constructed from letters just above the threshold of detection. This verified login would act as a portal to launching the image viewing software. The developed system was tested on three different types of monitor and five observers. Results indicate that the verified login was able to control access for displays below the optimal settings but was not as sensitive for adjustments above the optimum. However it is believed this is still of value as the lower presentation will compress the display gamma curve and reduce detail contrast. It also provides a minimum level of audit and quality control that might otherwise be missing. PMID:16046429

  14. Express Payload Project - A new method for rapid access to Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Uhran, Mark L.; Timm, Marc G.

    1993-01-01

    The deployment and permanent operation of Space Station Freedom will enable researchers to enter a new era in the 21st century, in which continuous on-orbit experimentation and observation become routine. In support of this objective, the Space Station Freedom Program Office has initiated the Express Payload Project. The fundamental project goal is to reduce the marginal cost associated with small payload development, integration, and operation. This is to be accomplished by developing small payload accommodations hardware and a new streamlined small payload integration process. Standardization of small payload interfaces, certification of small payload containers, and increased payload developer responsibility for mission success are key aspects of the Express Payload Project. As the project progresses, the principles will be applied to both pressurized payloads flown inside the station laboratories and unpressurized payloads attached to the station external structures. The increased access to space afforded by Space Station Freedom and the Express Payload Project has the potential to significantly expand the scope, magnitude, and success of future research in the microgravity environment.

  15. Sensitivity of watershed attributes to spatial resolution and interpolation method of LiDAR DEMs in three distinct landscapes

    NASA Astrophysics Data System (ADS)

    Goulden, T.; Hopkinson, C.; Jamieson, R.; Sterling, S.

    2014-03-01

    This study investigates scaling relationships of watershed area and stream networks delineated from LiDAR DEMs. The delineations are tested against spatial resolution, including 1, 5, 10, 25, and 50 m, and interpolation method, including Inverse Distance Weighting (IDW), Moving Average (MA), Universal Kriging (UK), Natural Neighbor (NN), and Triangular Irregular Networks (TIN). Study sites include Mosquito Creek, Scotty Creek, and Thomas Brook, representing landscapes with high, low, and moderate change in elevation, respectively. Results show scale-dependent irregularities in watershed area due to spatial resolution at Thomas Brook and Mosquito Creek. The highest sensitivity of watershed area to spatial resolution occurred at Scotty Creek, due to high incidence of LiDAR sensor measurement error and subtle changes in elevation. Length of drainage networks did not show a scaling relationship with spatial resolution, due to algorithmic complications of the stream initiation threshold. Stream lengths of main channels at Thomas Brook and Mosquito Creek displayed systematic increases in length with increasing spatial resolution, described through an average fractal dimension of 1.059. The scaling relationship between stream length and DEM resolution allows estimation of stream lengths from low-resolution DEMs in the absence of high-resolution DEMs. Single stream validation at Thomas Brook showed the 1 m DEM produced the lowest length error and highest spatial accuracy, at 3.7% and 71.3%, respectively. Single stream validation at Mosquito Creek showed the 25 m DEM produced the lowest length error, and the 1 m DEM the highest spatial accuracy, at 0.6% and 61.0%, respectively.

  16. Feasibility study of a high-spatial resolution x-ray computed tomography using sub-pixel shift method

    SciTech Connect

    Yoneyama, Akio Baba, Rika; Sumitani, Kazushi; Hirai, Yasuharu

    2015-02-23

    A high-spatial resolution X-ray computed tomography (CT) adopting a sub-pixel shift method has been developed. By calculating sectional images, using plural CT datasets obtained by scanning the X-ray imager, the spatial resolution can be reduced relative to the sub-pixel size of an X-ray imager. Feasibility observations of a biomedical sample were performed using 12-keV monochromatic synchrotron radiation and a photon-counting X-ray imager 174-μm pixels in size. Four CT measurements were performed to obtain datasets at different positions of the X-ray imager. Fine sectional images were obtained successfully, and the spatial resolution was estimated as 80-μm, which corresponds to just under half the pixel size of the imager. In addition, a fine 3D image was also obtained by scanning the imager two-dimensionally.

  17. Spatial frequency method and apparatus for investigating earth conductivity with high vertical resolution by induction techniques

    SciTech Connect

    Barber, T.D.

    1989-06-06

    This patent describes an induction sonde for measuring a characteristic of an earth formation traversed by a borehole comprising: a support member; transmitter means secured to the support member for transmitting an electromagnetic induction signal into the formation about the sonde; and receiver means secured to the support member a preselected distance from the transmitter means for receiving induction signals from the formation thereby determining the vertical response as a function of depth, the preselected distance being selected to provided a sonde with no zeros in the spatial frequency response in the frequency range of interest, the spatial frequency response being the Fourier transform of the vertical response.

  18. Elucidating the Functional Roles of Spatial Organization in Cross-Membrane Signal Transduction by a Hybrid Simulation Method.

    PubMed

    Chen, Jiawen; Xie, Zhong-Ru; Wu, Yinghao

    2016-07-01

    The ligand-binding of membrane receptors on cell surfaces initiates the dynamic process of cross-membrane signal transduction. It is an indispensable part of the signaling network for cells to communicate with external environments. Recent experiments revealed that molecular components in signal transduction are not randomly mixed, but spatially organized into distinctive patterns. These patterns, such as receptor clustering and ligand oligomerization, lead to very different gene expression profiles. However, little is understood about the molecular mechanisms and functional impacts of this spatial-temporal regulation in cross-membrane signal transduction. In order to tackle this problem, we developed a hybrid computational method that decomposes a model of signaling network into two simulation modules. The physical process of binding between receptors and ligands on cell surfaces are simulated by a diffusion-reaction algorithm, while the downstream biochemical reactions are modeled by stochastic simulation of Gillespie algorithm. These two processes are coupled together by a synchronization framework. Using this method, we tested the dynamics of a simple signaling network in which the ligand binding of cell surface receptors triggers the phosphorylation of protein kinases, and in turn regulates the expression of target genes. We found that spatial aggregation of membrane receptors at cellular interfaces is able to either amplify or inhibit downstream signaling outputs, depending on the details of clustering mechanism. Moreover, by providing higher binding avidity, the co-localization of ligands into multi-valence complex modulates signaling in very different ways that are closely related to the binding affinity between ligand and receptor. We also found that the temporal oscillation of the signaling pathway that is derived from genetic feedback loops can be modified by the spatial clustering of membrane receptors. In summary, our method demonstrates the functional

  19. Near surface velocity structure of Pacaya volcano using spatial autocorrelation method

    NASA Astrophysics Data System (ADS)

    Kenyon, L. M.; Waite, G. P.; Manzoni, P.

    2011-12-01

    Pacaya Volcano, Guatemala is a basaltic volcano in the Central American arc characterized by persistent degassing and nearly continuous nonharmonic tremor, coupled at times with lava effusion and/or coincident strombolian-style explosions. A moderate (VEI 2-3) eruption on 27 May 2010 destroyed part of the edifice and was followed by the opening of a new vent ~1.6 km south-southeast of the edifice. This change in activity prompted a field campaign, highlighted by the deployment of a small-aperture array of seismometers 1.1 km west of the summit in January 2011. The semi-circular array consisted of 11 short-period three-component seismometers with an aperture of 300 m and irregular radii of about 70 m and 150 m. During the deployment, we recorded primarily narrow-band tremor of volcanic and anthropogenic origin. We used the spatial auto-correlation (SPAC) method to generate band-limited dispersion curves from the tremor data and then inverted the dispersion curves for a velocity model. From 23 - 24 January we identified 16 segments of 300 s each using spectrograms, within which there were no events defined as LP, VLP or VT earthquakes. These were also periods during which there was little narrow-band tremor. The lack of directional dependence on the correlations confirms that there were no strong localized tremor sources. Because the station spacing was not ideal for SPAC analysis, we combined results for seven different radii, with a minimum of 3 station pairs each. The number of station pairs for each radius is given in parentheses after the distance: 73 (6), 82 (3), 100 (4), 133 (4), 145 (4), 153 (4) and 212 m (4). There are a total of 29 pairs of stations. The dispersion curve model found using only the vertical component shows Rayleigh wave velocities ranging from 1200 m/s at 1.5 Hz to 250 m/s at 8 Hz. The observed dispersion curve velocity range is consistent with other previously studied volcanoes where low velocities are found in the top 300 m. An analysis of

  20. Evaluation of Fuzzy-Logic Framework for Spatial Statistics Preserving Methods for Estimation of Missing Precipitation Data

    NASA Astrophysics Data System (ADS)

    El Sharif, H.; Teegavarapu, R. S.

    2012-12-01

    Spatial interpolation methods used for estimation of missing precipitation data at a site seldom check for their ability to preserve site and regional statistics. Such statistics are primarily defined by spatial correlations and other site-to-site statistics in a region. Preservation of site and regional statistics represents a means of assessing the validity of missing precipitation estimates at a site. This study evaluates the efficacy of a fuzzy-logic methodology for infilling missing historical daily precipitation data in preserving site and regional statistics. Rain gauge sites in the state of Kentucky, USA, are used as a case study for evaluation of this newly proposed method in comparison to traditional data infilling techniques. Several error and performance measures will be used to evaluate the methods and trade-offs in accuracy of estimation and preservation of site and regional statistics.

  1. Model-dependent spatial skill in pseudoproxy experiments testing climate field reconstruction methods for the Common Era

    NASA Astrophysics Data System (ADS)

    Smerdon, Jason E.; Coats, Sloan; Ault, Toby R.

    2016-03-01

    The spatial skill of four climate field reconstruction (CFR) methods is investigated using pseudoproxy experiments (PPEs) based on five last millennium and historical simulations from the Coupled and Paleo Model Intercomparison Projects Phases 5 and 3 (CMIP5/PMIP3) data archives. These simulations are used for the first time in a PPE context, the frameworks of which are constructed to test a recently assembled multiproxy network and multiple CFR techniques. The experiments confirm earlier findings demonstrating consistent methodological performance across the employed methods and spatially dependent reconstruction errors in all of the derived CFRs. Spectral biases in the reconstructed fields demonstrate that CFR methods can alone alter the ratio of spectral power at all locations in the field, independent of whether there are any spectral biases inherent in the underlying pseudoproxy series. The patterns of spectral biases are model dependent and indicate the potential for regions in the derived CFRs to be biased by changes in either low or high-frequency spectral power. CFR methods are also shown to alter the pattern of mean differences in the tropical Pacific during the Medieval Climate Anomaly and the Little Ice Age, with some model experiments indicating that CFR methodologies enhance the statistical likelihood of achieving larger mean differences between independent 300-year periods in the region. All of the characteristics of CFR performance are model dependent, indicating that CFR methods must be evaluated across multiple models and that conclusions from PPEs should be carefully connected to the spatial statistics of real-world climatic fields.

  2. A Comparison of Spatial Statistical Methods in a School Finance Policy Context

    ERIC Educational Resources Information Center

    Slagle, Mike

    2010-01-01

    A shortcoming of the conventional ordinary least squares (OLS) approaches for estimating median voter models of education demand is the inability to more fully explain the spatial relationships between neighboring school districts. Consequently, two school districts that appear to be descriptively similar in terms of conventional measures of…

  3. Technical Note: Measuring contrast- and noise-dependent spatial resolution of an iterative reconstruction method in CT using ensemble averaging

    SciTech Connect

    Yu, Lifeng Vrieze, Thomas J.; Leng, Shuai; Fletcher, Joel G.; McCollough, Cynthia H.

    2015-05-15

    Purpose: The spatial resolution of iterative reconstruction (IR) in computed tomography (CT) is contrast- and noise-dependent because of the nonlinear regularization. Due to the severe noise contamination, it is challenging to perform precise spatial-resolution measurements at very low-contrast levels. The purpose of this study was to measure the spatial resolution of a commercially available IR method using ensemble-averaged images acquired from repeated scans. Methods: A low-contrast phantom containing three rods (7, 14, and 21 HU below background) was scanned on a 128-slice CT scanner at three dose levels (CTDI{sub vol} = 16, 8, and 4 mGy). Images were reconstructed using two filtered-backprojection (FBP) kernels (B40 and B20) and a commercial IR method (sinogram affirmed iterative reconstruction, SAFIRE, Siemens Healthcare) with two strength settings (I40-3 and I40-5). The same scan was repeated 100 times at each dose level. The modulation transfer function (MTF) was calculated based on the edge profile measured on the ensemble-averaged images. Results: The spatial resolution of the two FBP kernels, B40 and B20, remained relatively constant across contrast and dose levels. However, the spatial resolution of the two IR kernels degraded relative to FBP as contrast or dose level decreased. For a given dose level at 16 mGy, the MTF{sub 50%} value normalized to the B40 kernel decreased from 98.4% at 21 HU to 88.5% at 7 HU for I40-3 and from 97.6% to 82.1% for I40-5. At 21 HU, the relative MTF{sub 50%} value decreased from 98.4% at 16 mGy to 90.7% at 4 mGy for I40-3 and from 97.6% to 85.6% for I40-5. Conclusions: A simple technique using ensemble averaging from repeated CT scans can be used to measure the spatial resolution of IR techniques in CT at very low contrast levels. The evaluated IR method degraded the spatial resolution at low contrast and high noise levels.

  4. Technical Note: Measuring contrast- and noise-dependent spatial resolution of an iterative reconstruction method in CT using ensemble averaging

    PubMed Central

    Yu, Lifeng; Vrieze, Thomas J.; Leng, Shuai; Fletcher, Joel G.; McCollough, Cynthia H.

    2015-01-01

    Purpose: The spatial resolution of iterative reconstruction (IR) in computed tomography (CT) is contrast- and noise-dependent because of the nonlinear regularization. Due to the severe noise contamination, it is challenging to perform precise spatial-resolution measurements at very low-contrast levels. The purpose of this study was to measure the spatial resolution of a commercially available IR method using ensemble-averaged images acquired from repeated scans. Methods: A low-contrast phantom containing three rods (7, 14, and 21 HU below background) was scanned on a 128-slice CT scanner at three dose levels (CTDIvol = 16, 8, and 4 mGy). Images were reconstructed using two filtered-backprojection (FBP) kernels (B40 and B20) and a commercial IR method (sinogram affirmed iterative reconstruction, SAFIRE, Siemens Healthcare) with two strength settings (I40-3 and I40-5). The same scan was repeated 100 times at each dose level. The modulation transfer function (MTF) was calculated based on the edge profile measured on the ensemble-averaged images. Results: The spatial resolution of the two FBP kernels, B40 and B20, remained relatively constant across contrast and dose levels. However, the spatial resolution of the two IR kernels degraded relative to FBP as contrast or dose level decreased. For a given dose level at 16 mGy, the MTF50% value normalized to the B40 kernel decreased from 98.4% at 21 HU to 88.5% at 7 HU for I40-3 and from 97.6% to 82.1% for I40-5. At 21 HU, the relative MTF50% value decreased from 98.4% at 16 mGy to 90.7% at 4 mGy for I40-3 and from 97.6% to 85.6% for I40-5. Conclusions: A simple technique using ensemble averaging from repeated CT scans can be used to measure the spatial resolution of IR techniques in CT at very low contrast levels. The evaluated IR method degraded the spatial resolution at low contrast and high noise levels. PMID:25979020

  5. A probabilistic spatial dengue fever risk assessment by a threshold-based-quantile regression method.

    PubMed

    Chiu, Chuan-Hung; Wen, Tzai-Hung; Chien, Lung-Chang; Yu, Hwa-Lung

    2014-01-01

    Understanding the spatial characteristics of dengue fever (DF) incidences is crucial for governmental agencies to implement effective disease control strategies. We investigated the associations between environmental and socioeconomic factors and DF geographic distribution, are proposed a probabilistic risk assessment approach that uses threshold-based quantile regression to identify the significant risk factors for DF transmission and estimate the spatial distribution of DF risk regarding full probability distributions. To interpret risk, return period was also included to characterize the frequency pattern of DF geographic occurrences. The study area included old Kaohsiung City and Fongshan District, two areas in Taiwan that have been affected by severe DF infections in recent decades. Results indicated that water-related facilities, including canals and ditches, and various types of residential area, as well as the interactions between them, were significant factors that elevated DF risk. By contrast, the increase of per capita income and its associated interactions with residential areas mitigated the DF risk in the study area. Nonlinear associations between these factors and DF risk were present in various quantiles, implying that water-related factors characterized the underlying spatial patterns of DF, and high-density residential areas indicated the potential for high DF incidence (e.g., clustered infections). The spatial distributions of DF risks were assessed in terms of three distinct map presentations: expected incidence rates, incidence rates in various return periods, and return periods at distinct incidence rates. These probability-based spatial risk maps exhibited distinct DF risks associated with environmental factors, expressed as various DF magnitudes and occurrence probabilities across Kaohsiung, and can serve as a reference for local governmental agencies. PMID:25302582

  6. A Probabilistic Spatial Dengue Fever Risk Assessment by a Threshold-Based-Quantile Regression Method

    PubMed Central

    Chiu, Chuan-Hung; Wen, Tzai-Hung; Chien, Lung-Chang; Yu, Hwa-Lung

    2014-01-01

    Understanding the spatial characteristics of dengue fever (DF) incidences is crucial for governmental agencies to implement effective disease control strategies. We investigated the associations between environmental and socioeconomic factors and DF geographic distribution, are proposed a probabilistic risk assessment approach that uses threshold-based quantile regression to identify the significant risk factors for DF transmission and estimate the spatial distribution of DF risk regarding full probability distributions. To interpret risk, return period was also included to characterize the frequency pattern of DF geographic occurrences. The study area included old Kaohsiung City and Fongshan District, two areas in Taiwan that have been affected by severe DF infections in recent decades. Results indicated that water-related facilities, including canals and ditches, and various types of residential area, as well as the interactions between them, were significant factors that elevated DF risk. By contrast, the increase of per capita income and its associated interactions with residential areas mitigated the DF risk in the study area. Nonlinear associations between these factors and DF risk were present in various quantiles, implying that water-related factors characterized the underlying spatial patterns of DF, and high-density residential areas indicated the potential for high DF incidence (e.g., clustered infections). The spatial distributions of DF risks were assessed in terms of three distinct map presentations: expected incidence rates, incidence rates in various return periods, and return periods at distinct incidence rates. These probability-based spatial risk maps exhibited distinct DF risks associated with environmental factors, expressed as various DF magnitudes and occurrence probabilities across Kaohsiung, and can serve as a reference for local governmental agencies. PMID:25302582

  7. Expanding Access to the Intrauterine Device in Public Health Facilities in Ethiopia: A Mixed-Methods Study

    PubMed Central

    Tilahun, Yewondwossen; Mehta, Sarah; Zerihun, Habtamu; Lew, Candace; Brooks, Mohamad I; Nigatu, Tariku; Hagos, Kidest Lulu; Asnake, Mengistu; Tasissa, Adeba; Ali, Seid; Desalegn, Ketsela; Adane, Girmay

    2016-01-01

    ABSTRACT In Ethiopia, modern contraceptive prevalence among currently married women nearly tripled over the last decade, but the method mix remains skewed toward short-acting methods. Since 2011, the Integrated Family Health Program (IFHP+), jointly implemented by Pathfinder International and John Snow Inc., has supported the Federal Ministry of Health to introduce intrauterine devices (IUDs) in more than 800 health centers across 4 regions to improve access to a wider range of methods. Between March and August 2014, Pathfinder conducted a mixed-methods study in 40 purposively selected health centers to assess shifts in the contraceptive method mix following introduction of IUDs using data from family planning registers; determine the characteristics of IUD users through a cross-sectional survey of 2,943 family planning clients who accepted the IUD; explore reasons for method discontinuation among 165 clients seeking IUD removal services; and identify facilitators and barriers to IUD use through focus group discussions (N = 115 clients) and key informant interviews (N = 36 providers, facility heads, and health office heads). Introduction of IUDs into the 40 health centers participating in the study was correlated with a statistically significant increase in the contribution of all long-acting reversible contraceptives (LARCs)—both IUDs and implants—to the method mix, from 6.9% in 2011 to 20.5% in 2014 (P<.001). Our study found that latent demand for the IUD was more prevalent than anticipated and that the method was acceptable to a broad cross-section of women. Of the 2,943 women who sought IUDs during the 6-month study period, 18.0% were new contraceptive users (i.e., those using a contraceptive method for the first time ever), 44.7% reported no educational attainment, 62.5% were from rural areas, and 59.3% were younger than 30 years old, with almost 3 in 10 (27.7%) under the age of 25. The most commonly cited reason for seeking IUD removal services

  8. Expanding Access to the Intrauterine Device in Public Health Facilities in Ethiopia: A Mixed-Methods Study.

    PubMed

    Tilahun, Yewondwossen; Mehta, Sarah; Zerihun, Habtamu; Lew, Candace; Brooks, Mohamad I; Nigatu, Tariku; Hagos, Kidest Lulu; Asnake, Mengistu; Tasissa, Adeba; Ali, Seid; Desalegn, Ketsela; Adane, Girmay

    2016-03-01

    In Ethiopia, modern contraceptive prevalence among currently married women nearly tripled over the last decade, but the method mix remains skewed toward short-acting methods. Since 2011, the Integrated Family Health Program (IFHP+), jointly implemented by Pathfinder International and John Snow Inc., has supported the Federal Ministry of Health to introduce intrauterine devices (IUDs) in more than 800 health centers across 4 regions to improve access to a wider range of methods. Between March and August 2014, Pathfinder conducted a mixed-methods study in 40 purposively selected health centers to assess shifts in the contraceptive method mix following introduction of IUDs using data from family planning registers; determine the characteristics of IUD users through a cross-sectional survey of 2,943 family planning clients who accepted the IUD; explore reasons for method discontinuation among 165 clients seeking IUD removal services; and identify facilitators and barriers to IUD use through focus group discussions (N = 115 clients) and key informant interviews (N = 36 providers, facility heads, and health office heads). Introduction of IUDs into the 40 health centers participating in the study was correlated with a statistically significant increase in the contribution of all long-acting reversible contraceptives (LARCs)-both IUDs and implants-to the method mix, from 6.9% in 2011 to 20.5% in 2014 (P<.001). Our study found that latent demand for the IUD was more prevalent than anticipated and that the method was acceptable to a broad cross-section of women. Of the 2,943 women who sought IUDs during the 6-month study period, 18.0% were new contraceptive users (i.e., those using a contraceptive method for the first time ever), 44.7% reported no educational attainment, 62.5% were from rural areas, and 59.3% were younger than 30 years old, with almost 3 in 10 (27.7%) under the age of 25. The most commonly cited reason for seeking IUD removal services was a desire to

  9. Into the environment of mosquito-borne disease: A spatial analysis of vector distribution using traditional and remotely sensed methods

    NASA Astrophysics Data System (ADS)

    Brown, Heidi E.

    Spatially explicit information is increasingly available for infectious disease modeling. However, such information is reluctantly or inappropriately incorporated. My dissertation research uses spatially explicit data to assess relationships between landscape and mosquito species distribution and discusses challenges regarding accurate predictive risk modeling. The goal of my research is to use remotely sensed environmental information and spatial statistical methods to better understand mosquito-borne disease epidemiology for improvement of public health responses. In addition to reviewing the progress of spatial infectious disease modeling, I present four research projects. I begin by evaluating the biases in surveillance data and build up to predictive modeling of mosquito species presence. In the first study I explore how mosquito surveillance trap types influence estimations of mosquito populations. Then. I use county-based human surveillance data and landscape variables to identify risk factors for West Nile virus disease. The third study uses satellite-based vegetation indices to identify spatial variation among West Nile virus vectors in an urban area and relates the variability to virus transmission dynamics. Finally, I explore how information from three satellite sensors of differing spatial and spectral resolution can be used to identify and distinguish mosquito habitat across central Connecticut wetlands. Analyses presented here constitute improvements to the prediction of mosquito distribution and therefore identification of disease risk factors. Current methods for mosquito surveillance data collection are labor intensive and provide an extremely limited, incomplete picture of the species composition and abundance. Human surveillance data offers additional challenges with respect to reporting bias and resolution, but is nonetheless informative in identifying environmental risk factors and disease transmission dynamics. Remotely sensed imagery supports

  10. Method and Apparatus to Access Optimum Strength During Processing of Precipitation Strengthened Alloys

    NASA Technical Reports Server (NTRS)

    Cantrell, John H. (Inventor); Yost, William T. (Inventor)

    2001-01-01

    A method and apparatus are provided which enable the nondestructive testing of strength of a heat treated alloy. An alloy is insonified with an ultrasonic signal. The resulting convoluted signal is detected and the acoustic nonlinearity parameter is determined. The acoustic nonlinearity parameter shows a peak corresponding to a peak in material strength.

  11. Suitability analysis for siting MSW landfills and its multicriteria spatial decision support system: method, implementation and case study.

    PubMed

    Demesouka, O E; Vavatsikos, A P; Anagnostopoulos, K P

    2013-05-01

    Multicriteria spatial decision support systems (MC-SDSS) have emerged as an integration of geographical information systems (GIS) and multiple criteria decision analysis (MCDA) methods for incorporating conflicting objectives and decision makers' (DMs') preferences into spatial decision models. This article presents a raster-based MC-SDSS that combines the analytic hierarchy process (AHP) and compromise programming methods, such as TOPSIS (technique for order preference by similarity to the ideal solution) and Ideal Point Methods. To the best of our knowledge it is the first time that a synergy of AHP and compromise programming methods is implemented in raster-driven GIS-based landfill suitability analysis. This procedure is supported by a spatial decision support system (SDSS) that was developed within a widely used commercial GIS software package. A real case study in the Thrace region in northeast Greece serves as a guide on how to conduct a suitability analysis for a MSW landfill site with the proposed MC-SDSS. Moreover, the procedure for identifying MSW disposal sites is accomplished by performing four computational models for synthesizing the DMs per criterion preferential system. Based on the case study results, a comparison analysis is performed according to suitability index estimations. According to them Euclidean distance metric and TOPSIS present strong similarities. When compared with Euclidean distance metric, TOPSIS seems to generate results closer to that derived by Manhattan distance metric. The comparison of Chebychev distance metric with all the other approaches revealed the greatest deviations. PMID:23453354

  12. Accessing indoor fungal contamination using conventional and molecular methods in Portuguese poultries.

    PubMed

    Viegas, C; Malta-Vacas, J; Sabino, R; Viegas, S; Veríssimo, C

    2014-03-01

    Epidemiological studies showed increased prevalence of respiratory symptoms and adverse changes in pulmonary function parameters in poultry workers, corroborating the increased exposure to risk factors, such as fungal load and their metabolites. This study aimed to determine the occupational exposure threat due to fungal contamination caused by the toxigenic isolates belonging to the complex of the species of Aspergillus flavus and also isolates from Aspergillus fumigatus species complex. The study was carried out in seven Portuguese poultries, using cultural and molecular methodologies. For conventional/cultural methods, air, surfaces, and litter samples were collected by impaction method using the Millipore Air Sampler. For the molecular analysis, air samples were collected by impinger method using the Coriolis μ air sampler. After DNA extraction, samples were analyzed by real-time PCR using specific primers and probes for toxigenic strains of the Aspergillus flavus complex and for detection of isolates from Aspergillus fumigatus complex. Through conventional methods, and among the Aspergillus genus, different prevalences were detected regarding the presence of Aspergillus flavus and Aspergillus fumigatus species complexes, namely: 74.5 versus 1.0 % in the air samples, 24.0 versus 16.0 % in the surfaces, 0 versus 32.6 % in new litter, and 9.9 versus 15.9 % in used litter. Through molecular biology, we were able to detect the presence of aflatoxigenic strains in pavilions in which Aspergillus flavus did not grow in culture. Aspergillus fumigatus was only found in one indoor air sample by conventional methods. Using molecular methodologies, however, Aspergillus fumigatus complex was detected in seven indoor samples from three different poultry units. The characterization of fungal contamination caused by Aspergillus flavus and Aspergillus fumigatus raises the concern of occupational threat not only due to the detected fungal load but also because of the

  13. Novel Scheme of Carrier Tri-reuse and Distribution Fiber Protection Based on Round Shift Method in Optical Access Network

    NASA Astrophysics Data System (ADS)

    Chen, Haibin; Gan, Chaoqin; Yin, Maojun; Ni, Cuiping

    2015-06-01

    A novel architecture of optical access network based on round shift method is proposed. Round shift method is composed by round service mode of carriers and cycle characteristic of 2×N arrayed waveguide grating (AWG). By utilizing the round service mode, every carrier is tri-reused to provide service for three different optical network units. Besides, in remote node, the 2×3N AWG can be replaced by three 2×N AWGs and AWGs' channel spacing is increased. So, the demand on RN's AWGs is decreased. Furthermore, based on the cycle characteristic of 2×N AWG, a 1+1 protection scheme is presented to provide independent protection for distribution fibers. Simulation and analysis show the proposed scheme works well.

  14. Over-constraints and a unified mobility method for general spatial mechanisms Part 2: Application of the principle

    NASA Astrophysics Data System (ADS)

    Lu, Wenjuan; Zeng, Daxing; Huang, Zhen

    2016-01-01

    The pre-research on mobility analysis presented a unified-mobility formula and a methodology based on reciprocal screw theory by HUANG, which focused on classical and modern parallel mechanisms. However its range of application needs to further extend to general multi-loop spatial mechanism. This kind of mechanism is not only more complex in structure but also with strong motion coupling among loops, making the mobility analysis even more complicated, and the relevant research has long been ignored. It is focused on how to apply the new principle for general spatial mechanism to those various multi-loop spatial mechanisms, and some new meaningful knowledge is further found. Several typical examples of the general multi-loop spatial mechanisms with motion couple even strong motion couple are considered. These spatial mechanisms include different closing way: over-constraint appearing in rigid closure, in movable closure, and in dynamic closure as well; these examples also include two different new methods to solve this kind of issue: the way to recognize over-constraints by analyzing relative movement between two connected links and by constructing a virtual loop to recognize over-constraints. In addition, over-constraint determination tabulation is brought to analyze the motion couple. The researches above are all based upon the screw theory. All these multi-loop spatial mechanisms with different kinds of structures can completely be solved by following the directions and examples, and the new mobility theory based on the screw theory is also proved to be valid. This study not only enriches and develops the theory and makes the theory more universal, but also has a special meaning for innovation in mechanical engineering.

  15. The spatial association between community air pollution and mortality: a new method of analyzing correlated geographic cohort data.

    PubMed Central

    Burnett, R; Ma, R; Jerrett, M; Goldberg, M S; Cakmak, S; Pope, C A; Krewski, D

    2001-01-01

    We present a new statistical model for linking spatial variation in ambient air pollution to mortality. The model incorporates risk factors measured at the individual level, such as smoking, and at the spatial level, such as air pollution. We demonstrate that the spatial autocorrelation in community mortality rates, an indication of not fully characterizing potentially confounding risk factors to the air pollution-mortality association, can be accounted for through the inclusion of location in the model assessing the effects of air pollution on mortality. Our methods are illustrated with an analysis of the American Cancer Society cohort to determine whether all cause mortality is associated with concentrations of sulfate particles. The relative risk associated with a 4.2 microg/m(3) interquartile range of sulfate distribution for all causes of death was 1.051 (95% confidence interval 1.036-1.066) based on the Cox proportional hazards survival model, assuming subjects were statistically independent. Inclusion of community-based random effects yielded a relative risk of 1.055 (1.033, 1.077), which represented a doubling in the residual variance compared to that estimated by the Cox model. Residuals from the random-effects model displayed strong evidence of spatial autocorrelation (p = 0.0052). Further inclusion of a location surface reduced the sulfate relative risk and the evidence for autocorrelation as the complexity of the location surface increased, with a range in relative risks of 1.055-1.035. We conclude that these data display both extravariation and spatial autocorrelation, characteristics not captured by the Cox survival model. Failure to account for extravariation and spatial autocorrelation can lead to an understatement of the uncertainty of the air pollution association with mortality. PMID:11427386

  16. An Innovative Method of Measuring Changes in Access to Healthful Foods in School Lunch Programs: Findings from a Pilot Evaluation

    PubMed Central

    Hawkes, Allison P.; Weinberg, Stacy L.; Janusz, Ruth; Demont-Heinrich, Christine; Vogt, Richard L.

    2016-01-01

    Introduction A large local health department in Colorado partnered with 15 school districts to develop an approach to evaluate changes in access to healthy foods in reimbursable school lunches and a la carte offerings. Materials and Methods School district nutrition managers were engaged at the start of this project. Health department dietitians developed criteria to classify food items as “Lower Fat and less added Sugar” (LFS) and “Higher Fat and more added Sugar” (HFS) based on the percentage of calories from fat and grams of added sugar. Lunch production sheets were obtained for two time periods, food items and the number of planned servings recorded. LFS and HFS planned servings were summed for each time period, and a LFS to HFS ratio calculated by dividing LFS planned servings by HFS planned servings. Additional analyses included calculating LFS: HFS ratios by school district, and for a la carte offerings. Results In 2009, the LFS: HFS ratio was 2.08, in 2011, 3.71 (P<0.0001). The method also detected changes in ratios at the school district level. For a la carte items, in 2009 the ratio of LFS: HFS was 0.53, and in 2011, 0.61 (not statistically significant). Conclusions This method detected an increase in the LFS: HFS ratio over time and demonstrated that the school districts improved access to healthful food/drink by changing the contents of reimbursable school lunches. The evaluation method discussed here can generate information that districts can use in helping sustain and expand their efforts to create healthier environments for children and adults. Although federal regulations now cover all food and beverages served during the school day, there are still opportunities to improve and measure changes in food served in other settings such as child care centers, youth correction facilities, or in schools not participating in the National School Lunch Program. PMID:26800523

  17. Spatially varying embedded stochastic galerkin methods for steady-state PDEs.

    SciTech Connect

    Cyr, Eric Christopher

    2013-07-01

    Existing discretizations for stochastic PDEs, based on a tensor product between the deterministic basis and the stochastic basis, treat the required resolution of uncertainty as uniform across the physical domain. However, solutions to many PDEs of interest exhibit spatially localized features that may result in uncertainty being severely over or under-resolved by existing discretizations. In this report, we explore the mechanics and accuracy of using a spatially varying stochastic expansion. This is achieved through an adaptive refinement algorithm where simple error estimates are used to independently drive refinement of the stochastic basis at each point in the physical domain. Results are presented comparing the accuracy of the adaptive techinque to the accuracy achieved using uniform refinement.

  18. On methods of access to the structure of social representations: the example of Europe.

    PubMed

    Castel, Philippe; Morlot, Rachel; Lacassagne, Marie-Françoise

    2012-11-01

    The aim of this study is to identify the logic behind a range of statistical methods used to reveal the structure of social representations. Subjects (N = 317) were asked to answer the following question: "For each category of European person, please indicate which other European he would most like to have contact with". The results of the similarity analysis lead us to the conclusion that there is an ethnocentric bias, and reveal the central factor of the representation. The representation obtained by factorial correspondence analysis seems closer to current reality and enables us to understand the divisions that have structured Europe and remained embedded in the subjects. Thus, the choice of analytical method is not merely anecdotal, given that representations obtained from the same data can vary immensely. PMID:23156927

  19. Information Accessibility of the Charcoal Burning Suicide Method in Mainland China

    PubMed Central

    Cheng, Qijin; Chang, Shu-Sen; Guo, Yingqi; Yip, Paul S. F.

    2015-01-01

    Background There has been a marked rise in suicide by charcoal burning (CB) in some East Asian countries but little is known about its incidence in mainland China. We examined media-reported CB suicides and the availability of online information about the method in mainland China. Methods We extracted and analyzed data for i) the characteristics and trends of fatal and nonfatal CB suicides reported by mainland Chinese newspapers (1998–2014); ii) trends and geographic variations in online searches using keywords relating to CB suicide (2011–2014); and iii) the content of Internet search results. Results 109 CB suicide attempts (89 fatal and 20 nonfatal) were reported by newspapers in 13 out of the 31 provinces or provincial-level-municipalities in mainland China. There were increasing trends in the incidence of reported CB suicides and in online searches using CB-related keywords. The province-level search intensities were correlated with CB suicide rates (Spearman’s correlation coefficient = 0.43 [95% confidence interval: 0.08–0.68]). Two-thirds of the web links retrieved using the search engine contained detailed information about the CB suicide method, of which 15% showed pro-suicide attitudes, and the majority (86%) did not encourage people to seek help. Limitations The incidence of CB suicide was based on newspaper reports and likely to be underestimated. Conclusions Mental health and suicide prevention professionals in mainland China should be alert to the increased use of this highly lethal suicide method. Better surveillance and intervention strategies need to be developed and implemented. PMID:26474297

  20. Hybrid methods for improving information access in clinical documents: concept, assertion, and relation identification

    PubMed Central

    Minard, Anne-Lyse; Ligozat, Anne-Laure; Ben Abacha, Asma; Bernhard, Delphine; Cartoni, Bruno; Deléger, Louise; Grau, Brigitte; Rosset, Sophie; Zweigenbaum, Pierre

    2011-01-01

    Objective This paper describes the approaches the authors developed while participating in the i2b2/VA 2010 challenge to automatically extract medical concepts and annotate assertions on concepts and relations between concepts. Design The authors'approaches rely on both rule-based and machine-learning methods. Natural language processing is used to extract features from the input texts; these features are then used in the authors' machine-learning approaches. The authors used Conditional Random Fields for concept extraction, and Support Vector Machines for assertion and relation annotation. Depending on the task, the authors tested various combinations of rule-based and machine-learning methods. Results The authors'assertion annotation system obtained an F-measure of 0.931, ranking fifth out of 21 participants at the i2b2/VA 2010 challenge. The authors' relation annotation system ranked third out of 16 participants with a 0.709 F-measure. The 0.773 F-measure the authors obtained on concept extraction did not make it to the top 10. Conclusion On the one hand, the authors confirm that the use of only machine-learning methods is highly dependent on the annotated training data, and thus obtained better results for well-represented classes. On the other hand, the use of only a rule-based method was not sufficient to deal with new types of data. Finally, the use of hybrid approaches combining machine-learning and rule-based approaches yielded higher scores. PMID:21597105

  1. Numerical method for solution of systems of non-stationary spatially one-dimensional nonlinear differential equations

    NASA Technical Reports Server (NTRS)

    Morozov, S. K.; Krasitskiy, O. P.

    1978-01-01

    A computational scheme and a standard program is proposed for solving systems of nonstationary spatially one-dimensional nonlinear differential equations using Newton's method. The proposed scheme is universal in its applicability and its reduces to a minimum the work of programming. The program is written in the FORTRAN language and can be used without change on electronic computers of type YeS and BESM-6. The standard program described permits the identification of nonstationary (or stationary) solutions to systems of spatially one-dimensional nonlinear (or linear) partial differential equations. The proposed method may be used to solve a series of geophysical problems which take chemical reactions, diffusion, and heat conductivity into account, to evaluate nonstationary thermal fields in two-dimensional structures when in one of the geometrical directions it can take a small number of discrete levels, and to solve problems in nonstationary gas dynamics.

  2. Implementing Direct Access to Low-Dose Computed Tomography in General Practice—Method, Adaption and Outcome

    PubMed Central

    Guldbrandt, Louise Mahncke; Rasmussen, Torben Riis; Rasmussen, Finn; Vedsted, Peter

    2014-01-01

    Background Early detection of lung cancer is crucial as the prognosis depends on the disease stage. Chest radiographs has been the principal diagnostic tool for general practitioners (GPs), but implies a potential risk of false negative results, while computed tomography (CT) has a higher sensitivity. The aim of this study was to describe the implementation of direct access to low-dose CT (LDCT) from general practice. Methods We conducted a cohort study nested in a randomised study. A total of 119 general practices with 266 GPs were randomised into two groups. Intervention GPs were offered direct access to chest LDCT combined with a Continuing Medical Education (CME) meeting on lung cancer diagnosis. Results During a 19-month period, 648 patients were referred to LDCT (0.18/1000 adults on GP list/month). Half of the patients needed further diagnostic work-up, and 15 (2.3%, 95% CI: 1.3–3.8%) of the patients had lung cancer; 60% (95% CI: 32.3–83.7%) in a localised stage. The GP referral rate was 61% higher for CME participants compared to non-participants. Conclusion Of all patients referred to LDCT, 2.3% were diagnosed with lung cancer with a favourable stage distribution. Half of the referred patients needed additional diagnostic work-up. There was an association between participation in CME and use of CT scan. The proportion of cancers diagnosed through the usual fast-track evaluation was 2.2 times higher in the group of CME-participating GPs. The question remains if primary care case-finding with LDCT is a better option for patients having signs and symptoms indicating lung cancer than a screening program. Whether open access to LDCT may provide earlier diagnosis of lung cancer is yet unknown and a randomised trial is required to assess any effect on outcome. Trial Registration Clinicaltrials.gov NCT01527214 PMID:25383780

  3. Modeling Spatial Structure of Rock Fracture Surfaces Before and After Shear Test: A Method for Estimating Morphology of Damaged Zones

    NASA Astrophysics Data System (ADS)

    Babanouri, Nima; Karimi Nasab, Saeed

    2015-05-01

    This paper deals with the structural analysis of rock fracture roughness, and accordingly, a method is developed for estimating/predicting the post-shearing 3D geometry of the fracture surface. For this purpose, surfaces of three natural rock fractures were digitized and studied before and after the direct shear test. The variogram analysis of the surfaces indicated a strong non-linear trend in the topography data. Hence, the spatial variability of the rock fracture surfaces was decomposed to: one deterministic component, characterized by a high-order polynomial representing the large-scale undulations, and one stochastic component, described by the variogram of residuals representing the small-scale roughness. Using an image-processing technique, a total of 343 damage zones with different sizes, shapes, initial roughness characteristics, local stress fields, and/or asperity strength values were spatially located and clustered. In order to characterize the overall spatial structure of the degraded zones, the concept of the `pseudo-zonal variogram' was introduced. The results showed that the spatial continuity at the damage zones increases due to the asperity degradation. The increase in the variogram range is anisotropic and tends to be higher along the shearing. Consequently, the direction of maximum continuity rotates towards the shear direction. After modeling the evolution of the spatial structure with shearing and detecting boundaries of the degraded areas, a methodology was presented to provide a regression-kriging estimate of the morphology of sheared surfaces. The proposed method can be considered as a cost-free and reasonably accurate alternative to expensive techniques of scanning the rock fracture surface after the shear test.

  4. Efficient data extraction method for near-infrared spectroscopy (NIRS) systems with high spatial and temporal resolution.

    PubMed

    Choi, Jong-Kwan; Choi, Min-Gyu; Kim, Jae-Myoung; Bae, Hyeon-Min

    2013-04-01

    An hardware-efficient method for the extraction of hemodynamic responses in near-infrared spectroscopy systems is proposed to increase the spatial and temporal resolution. The performance improvement is attributed to high signal-to-noise ratio receivers, a modulation scheme, and a multi-input-multi-output based data extraction algorithm. The proposed system shows more than twofold improvement in the figure of merit compared to conventional designs. Experimental results support the validity of the proposed system. PMID:23853299

  5. Interferometric method for phase calibration in liquid crystal spatial light modulators using a self-generated diffraction-grating.

    PubMed

    Fuentes, José Luis Martínez; Fernández, Enrique J; Prieto, Pedro M; Artal, Pablo

    2016-06-27

    An auto-referenced interferometric method for calibrating phase modulation of parallel-aligned liquid crystal (PAL) spatial light modulators (SLM) is described. The method is experimentally straightforward, robust, and requires solely of a collimated beam, with no need of additional optics. This method uses the SLM itself to create a tilted plane wave and a reference wave which mutually interfere. These waves are codified by means of a binary diffraction grating and a uniformly distributed gray level area (piston) into the SLM surface. Phase shift for each gray level addressed to the piston section can then be evaluated. Phase modulation on the SLM can also be retrieved with the proposed method over spatially resolved portions of the surface. Phase information obtained with this novel method is compared to other well established calibration procedures, requiring extra elements and more elaborated optical set-ups. The results show a good agreement with previous methods. The advantages of the new method include high mechanical stability, faster performance, and a significantly easier practical implementation. PMID:27410574

  6. An improved k-NN method based on multiple-point statistics for classification of high-spatial resolution imagery

    NASA Astrophysics Data System (ADS)

    Tang, Y.; Jing, L.; Li, H.; Liu, Q.; Ding, H.

    2016-04-01

    In this paper, the potential of multiple-point statistics (MPS) for object-based classification is explored using a modified k-nearest neighbour (k-NN) classification method (MPk-NN). The method first utilises a training image derived from a classified map to characterise the spatial correlation between multiple points of land cover classes, overcoming the limitations of two-point geostatistical methods, and then the spatial information in the form of multiple-point probability is incorporated into the k-NN classifier. The remotely sensed image of an IKONOS subscene of the Beijing urban area was selected to evaluate the method. The image was object-based classified using the MPk-NN method and several alternatives, including the traditional k-NN, the geostatistically weighted k-NN, the Bayesian method, the decision tree classifier (DTC), and the support vector machine classifier (SVM). It was demonstrated that the MPk-NN approach can achieve greater classification accuracy relative to the alternatives, which are 82.05% and 89.12% based on pixel and object testing data, respectively. Thus, the proposed method is appropriate for object-based classification.

  7. A Novel, Open Access Method to Assess Sleep Duration Using a Wrist-Worn Accelerometer

    PubMed Central

    Anderson, Kirstie N.; Denton, Sarah J.; Oliver, James; Catt, Michael; Abell, Jessica G.; Kivimäki, Mika; Trenell, Michael I.; Singh-Manoux, Archana

    2015-01-01

    Wrist-worn accelerometers are increasingly being used for the assessment of physical activity in population studies, but little is known about their value for sleep assessment. We developed a novel method of assessing sleep duration using data from 4,094 Whitehall II Study (United Kingdom, 2012–2013) participants aged 60–83 who wore the accelerometer for 9 consecutive days, filled in a sleep log and reported sleep duration via questionnaire. Our sleep detection algorithm defined (nocturnal) sleep as a period of sustained inactivity, itself detected as the absence of change in arm angle greater than 5 degrees for 5 minutes or more, during a period recorded as sleep by the participant in their sleep log. The resulting estimate of sleep duration had a moderate (but similar to previous findings) agreement with questionnaire based measures for time in bed, defined as the difference between sleep onset and waking time (kappa = 0.32, 95%CI:0.29,0.34) and total sleep duration (kappa = 0.39, 0.36,0.42). This estimate was lower for time in bed for women, depressed participants, those reporting more insomnia symptoms, and on weekend days. No such group differences were found for total sleep duration. Our algorithm was validated against data from a polysomnography study on 28 persons which found a longer time window and lower angle threshold to have better sensitivity to wakefulness, while the reverse was true for sensitivity to sleep. The novelty of our method is the use of a generic algorithm that will allow comparison between studies rather than a “count” based, device specific method. PMID:26569414

  8. Comparison of methods to assess the enzyme accessibility and hydrolysis of pretreated lignocellulosic substrates.

    PubMed

    Chandra, Richard P; Ewanick, Shannon M; Chung, Pablo A; Au-Yeung, Kathy; Del Rio, Luis; Mabee, Warren; Saddler, Jack N

    2009-08-01

    Fiber size analysis, water retention value, and Simons' stain measurements were assessed for their potential to predict the susceptibility of a given substrate to enzymatic hydrolysis. Slight modifications were made to the fiber size analysis and water retention protocols to adapt these measurements to evaluate substrates for cellulolytic hydrolysis rather than pulps for papermaking. Lodgepole pine was pretreated by the steam and ethanol-organosolv processes under varying conditions. The Simons' stain procedure proved to be an effective method for indicating the potential ease of enzymatic hydrolysis of substrates pretreated by either process or when the pretreatment conditions were altered. PMID:19357812

  9. An impedance method for spatial sensing of 3D cell constructs--towards applications in tissue engineering.

    PubMed

    Canali, C; Mazzoni, C; Larsen, L B; Heiskanen, A; Martinsen, Ø G; Wolff, A; Dufva, M; Emnéus, J

    2015-09-01

    We present the characterisation and validation of multiplexed 4-terminal (4T) impedance measurements as a method for sensing the spatial location of cell aggregates within large three-dimensional (3D) gelatin scaffolds. The measurements were performed using an array of four rectangular chambers, each having eight platinum needle electrodes for parallel analysis. The electrode positions for current injection and voltage measurements were optimised by means of finite element simulations to maximise the sensitivity field distribution and spatial resolution. Eight different 4T combinations were experimentally tested in terms of the spatial sensitivity. The simulated sensitivity fields were validated using objects (phantoms) with different conductivity and size placed in different positions inside the chamber. This provided the detection limit (volume sensitivity) of 16.5%, i.e. the smallest detectable volume with respect to the size of the measurement chamber. Furthermore, the possibility for quick single frequency analysis was demonstrated by finding a common frequency of 250 kHz for all the presented electrode combinations. As final proof of concept, a high density of human hepatoblastoma (HepG2) cells were encapsulated in gelatin to form artificial 3D cell constructs and detected when placed in different positions inside large gelatin scaffolds. Taken together, these results open new perspectives for impedance-based sensing technologies for non-invasive monitoring in tissue engineering applications providing spatial information of constructs within biologically relevant 3D environments. PMID:26198701

  10. An EPR spin probe method for characterizing changes in the accessible regions of coal upon oxidation

    SciTech Connect

    Sady, W.; Kispert, L.D.; Spears, D.R.

    1992-01-01

    Eight Argonne Premium Coal Samples (APCS) were weathered in air and the structural and chemical changes that upon swelling with toluene and pyridine were, examined by an EPR spin probe method developed in this laboratory. Under mild oxidation conditions and swelling with toluene large structural changes were observed for lignite (Beulah-Zap) which suggested the collapse of the coal structure. This did not occur for higher rank coal. Upon oxidation and swelling with toluene and pyridine an increase occurred in the amino substituted spin probe concentration for coals with the carbon percent above 80%. A maximum was found for the creation of 5 {Angstrom} diameter pores upon swelling with pyridine at 85% C.

  11. A compensation method for the full phase retardance nonuniformity in phase-only liquid crystal on silicon spatial light modulators.

    PubMed

    Teng, Long; Pivnenko, Mike; Robertson, Brian; Zhang, Rong; Chu, Daping

    2014-10-20

    A simple and efficient compensation method for the full correction of both the anisotropic and isotropic nonuniformity of the light phase retardance in a liquid crystal (LC) layer is presented. This is achieved by accurate measurement of the spatial variation of the LC layer's thickness with the help of a calibrated liquid crystal wedge, rather than solely relying on the light intensity profile recorded using two crossed polarizers. Local phase retardance as a function of the applied voltage is calculated with its LC thickness and a set of reference data measured from the intensity of the reflected light using two crossed polarizers. Compensation of the corresponding phase nonuniformity is realized by applying adjusted local voltage signals for different grey levels. To demonstrate its effectiveness, the proposed method is applied to improve the performance of a phase-only liquid crystal on silicon (LCOS) spatial light modulator (SLM). The power of the first diffraction order measured with the binary phase gratings compensated by this method is compared with that compensated by the conventional crossed-polarizer method. The results show that the phase compensation method proposed here can increase the dynamic range of the first order diffraction power significantly from 15~21 dB to over 38 dB, while the crossed-polarizer method can only increase it to 23 dB. PMID:25401672

  12. Voxelization algorithms for geospatial applications: Computational methods for voxelating spatial datasets of 3D city models containing 3D surface, curve and point data models.

    PubMed

    Nourian, Pirouz; Gonçalves, Romulo; Zlatanova, Sisi; Ohori, Ken Arroyo; Vu Vo, Anh

    2016-01-01

    Voxel representations have been used for years in scientific computation and medical imaging. The main focus of our research is to provide easy access to methods for making large-scale voxel models of built environment for environmental modelling studies while ensuring they are spatially correct, meaning they correctly represent topological and semantic relations among objects. In this article, we present algorithms that generate voxels (volumetric pixels) out of point cloud, curve, or surface objects. The algorithms for voxelization of surfaces and curves are a customization of the topological voxelization approach [1]; we additionally provide an extension of this method for voxelization of point clouds. The developed software has the following advantages:•It provides easy management of connectivity levels in the resulting voxels.•It is not dependant on any external library except for primitive types and constructs; therefore, it is easy to integrate them in any application.•One of the algorithms is implemented in C++ and C for platform independence and efficiency. PMID:27408832

  13. Spatial convergence properties of the diamond difference method in x,y geometry

    SciTech Connect

    Larsen, E.W.

    1982-04-01

    It is shown, for a model numerical experiment, that the diamond difference (DD) solution of the x,y geometry discrete ordinates equations, with a fixed angular quadrature set, converges in the norm with less than a second-order convergence rate as the spatial mesh is refined, and that the value of this convergence rate depends on the definition of the error norm. However, this same experiment suggests that numerical integrals of DD solution do converge with a second-order convergence rate.

  14. A Method for Manipulating Blood Glucose and Measuring Resulting Changes in Cognitive Accessibility of Target Stimuli.

    PubMed

    Prokosch, Marjorie L; Hill, Sarah E

    2016-01-01

    Much research in social psychology has investigated the impact of bodily energy need on cognition and decision-making. As such, blood glucose, the body's primary energy source, has been of special interest to researchers for years. Fluctuations in blood glucose have been linked to a variety of changes in cognitive and behavioral processes, such as self-control, political attitudes, and eating behavior. To help meet growing interest in the links between bodily energy need and these processes, this manuscript offers a simple methodology to experimentally manipulate blood glucose using a fasting procedure followed by administration of a sugar-sweetened, unsweetened, or artificially-sweetened beverage. This is followed by presentation of a method for measuring resulting changes in implicit cognition using a lexical decision-task. In this task, participants are asked to identify whether strings of letters are words or non-words and response latencies are recorded. Sample results from a recent publication are presented as an example of the applications for the experimental manipulation of blood glucose and the lexical decision task measures. PMID:27585282

  15. New tools and methods for direct programmatic access to the dbSNP relational database

    PubMed Central

    Saccone, Scott F.; Quan, Jiaxi; Mehta, Gaurang; Bolze, Raphael; Thomas, Prasanth; Deelman, Ewa; Tischfield, Jay A.; Rice, John P.

    2011-01-01

    Genome-wide association studies often incorporate information from public biological databases in order to provide a biological reference for interpreting the results. The dbSNP database is an extensive source of information on single nucleotide polymorphisms (SNPs) for many different organisms, including humans. We have developed free software that will download and install a local MySQL implementation of the dbSNP relational database for a specified organism. We have also designed a system for classifying dbSNP tables in terms of common tasks we wish to accomplish using the database. For each task we have designed a small set of custom tables that facilitate task-related queries and provide entity-relationship diagrams for each task composed from the relevant dbSNP tables. In order to expose these concepts and methods to a wider audience we have developed web tools for querying the database and browsing documentation on the tables and columns to clarify the relevant relational structure. All web tools and software are freely available to the public at http://cgsmd.isi.edu/dbsnpq. Resources such as these for programmatically querying biological databases are essential for viably integrating biological information into genetic association experiments on a genome-wide scale. PMID:21037260

  16. Application of finite-element methods to dynamic analysis of flexible spatial and co-planar linkage systems, part 2

    NASA Technical Reports Server (NTRS)

    Dubowsky, Steven

    1989-01-01

    An approach is described to modeling the flexibility effects in spatial mechanisms and manipulator systems. The method is based on finite element representations of the individual links in the system. However, it should be noted that conventional finite element methods and software packages will not handle the highly nonlinear dynamic behavior of these systems which results form their changing geometry. In order to design high-performance lightweight systems and their control systems, good models of their dynamic behavior which include the effects of flexibility are required.

  17. A comparison of spatial interpolation methods for soil temperature over a complex topographical region

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Tang, Xiao-Ping; Ma, Xue-Qing; Liu, Hong-Bin

    2015-06-01

    Soil temperature variability data provide valuable information on understanding land-surface ecosystem processes and climate change. This study developed and analyzed a spatial dataset of monthly mean soil temperature at a depth of 10 cm over a complex topographical region in southwestern China. The records were measured at 83 stations during the period of 1961-2000. Nine approaches were compared for interpolating soil temperature. The accuracy indicators were root mean square error (RMSE), modelling efficiency (ME), and coefficient of residual mass (CRM). The results indicated that thin plate spline with latitude, longitude, and elevation gave the best performance with RMSE varying between 0.425 and 0.592 °C, ME between 0.895 and 0.947, and CRM between -0.007 and 0.001. A spatial database was developed based on the best model. The dataset showed that larger seasonal changes of soil temperature were from autumn to winter over the region. The northern and eastern areas with hilly and low-middle mountains experienced larger seasonal changes.

  18. a Comparison Study of Different Marker Selection Methods for Spectral-Spatial Classification of Hyperspectral Images

    NASA Astrophysics Data System (ADS)

    Akbari, D.; Safari, A. R.; Homayouni, S.; Khazai, S.

    2015-12-01

    An effective approach based on the Minimum Spanning Forest (MSF), grown from automatically selected markers using Support Vector Machines (SVM), has been proposed for spectral-spatial classification of hyperspectral images by Tarabalka et al. This paper aims at improving this approach by using image segmentation to integrate the spatial information into marker selection process. In this study, the markers are extracted from the classification maps, obtained by both SVM and segmentation algorithms, and then are used to build the MSF. The segmentation algorithms are the watershed, expectation maximization (EM) and hierarchical clustering. These algorithms are used in parallel and independently to segment the image. Moreover, the pixels of each class, with the largest population in the classification map, are kept for each region of the segmentation map. Lastly, the most reliable classified pixels are chosen from among the exiting pixels as markers. Two benchmark urban hyperspectral datasets are used for evaluation: Washington DC Mall and Berlin. The results of our experiments indicate that, compared to the original MSF approach, the marker selection using segmentation algorithms leads in more accurate classification maps.

  19. A comparison of spatial interpolation methods for soil temperature over a complex topographical region

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Tang, Xiao-Ping; Ma, Xue-Qing; Liu, Hong-Bin

    2016-08-01

    Soil temperature variability data provide valuable information on understanding land-surface ecosystem processes and climate change. This study developed and analyzed a spatial dataset of monthly mean soil temperature at a depth of 10 cm over a complex topographical region in southwestern China. The records were measured at 83 stations during the period of 1961-2000. Nine approaches were compared for interpolating soil temperature. The accuracy indicators were root mean square error (RMSE), modelling efficiency (ME), and coefficient of residual mass (CRM). The results indicated that thin plate spline with latitude, longitude, and elevation gave the best performance with RMSE varying between 0.425 and 0.592 °C, ME between 0.895 and 0.947, and CRM between -0.007 and 0.001. A spatial database was developed based on the best model. The dataset showed that larger seasonal changes of soil temperature were from autumn to winter over the region. The northern and eastern areas with hilly and low-middle mountains experienced larger seasonal changes.

  20. Comparison of four methods of calculating the symmetry of spatial-temporal parameters of gait.

    PubMed

    Błażkiewicz, Michalina; Wiszomirska, Ida; Wit, Andrzej

    2014-01-01

    Although gait symmetry is being evaluated and reported in the literature with increasing frequency, there is still no generally accepted standard for assessing symmetry, making it difficult to compare studies and establish criteria to guide clinical decision-making. The purpose of this study was to ascertain whether gait symmetry in healthy subjects is consistent when assessed using various coefficients (RI, SI, GA, and SA), and if possible to identify a gait symmetry coefficient with the highest diagnostic utility. The study involved a group of 58 healthy university-level students of physical education and secondary school students aged 20.03±0.97. Measurements of spatial-temporal gait parameters were conducted using the ZEBRIS platform. Our analysis supports existing recommendations that the symmetry index (SI) should be used as the most sensitive assessment of gait symmetry on the basis of spatial-temporal parameters in healthy subjects. Moreover, we developed normative values of individual features for diagnostic purposes. PMID:24708092

  1. A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes

    USGS Publications Warehouse

    Shanafield, Margaret; Niswonger, Richard G.; Prudic, David E.; Pohll, Greg; Susfalk, Richard; Panday, Sorab

    2014-01-01

    Infiltration along ephemeral channels plays an important role in groundwater recharge in arid regions. A model is presented for estimating spatial variability of seepage due to streambed heterogeneity along channels based on measurements of streamflow-front velocities in initially dry channels. The diffusion-wave approximation to the Saint-Venant equations, coupled with Philip's equation for infiltration, is connected to the groundwater model MODFLOW and is calibrated by adjusting the saturated hydraulic conductivity of the channel bed. The model is applied to portions of two large water delivery canals, which serve as proxies for natural ephemeral streams. Estimated seepage rates compare well with previously published values. Possible sources of error stem from uncertainty in Manning's roughness coefficients, soil hydraulic properties and channel geometry. Model performance would be most improved through more frequent longitudinal estimates of channel geometry and thalweg elevation, and with measurements of stream stage over time to constrain wave timing and shape. This model is a potentially valuable tool for estimating spatial variability in longitudinal seepage along intermittent and ephemeral channels over a wide range of bed slopes and the influence of seepage rates on groundwater levels.

  2. Spatial dynamics of farming practices in the Seine basin: methods for agronomic approaches on a regional scale.

    PubMed

    Mignolet, C; Schott, C; Benoît, M

    2007-04-01

    A research procedure is proposed which aims to analyse the agricultural spatial dynamics during the last thirty years using two levels of organisation of farming activity: the agricultural production system and the cropping system. Based on methods of statistical mapping and data mining, this procedure involves modelling the diversity of production systems and cropping systems (crop successions and sequences of cultural practices for each crop) in the form of classes independently of their localisation within the basin. It identifies homogeneous regions made up of groups of contiguous agricultural districts which exhibit similar combinations of production systems, crop successions or cultural practices during a given period of time. The results show a major increase in arable farms since 1970 at the expense of dairy farms and mixed cropping/livestock. This trend however appeared to be greatly spatially differentiated according to the agricultural districts, since livestock remained important on the edges of the basin, whereas it practically disappeared in its centre. The crop successions practiced in the basin and the cultural practices used on them also appear to be spatially differentiated, although the link to the production systems is not always clear. Thus it appears pertinent to combine the analysis of the two levels of organisation of the agriculture (methods of land use described by the concept of cropping system, and also the production systems into which the cropping systems fit) in the context of an environmental problem. PMID:17316763

  3. An inverse method for determining the spatially resolved properties of viscoelastic–viscoplastic three-dimensional printed materials

    PubMed Central

    Chen, X.; Ashcroft, I. A.; Wildman, R. D.; Tuck, C. J.

    2015-01-01

    A method using experimental nanoindentation and inverse finite-element analysis (FEA) has been developed that enables the spatial variation of material constitutive properties to be accurately determined. The method was used to measure property variation in a three-dimensional printed (3DP) polymeric material. The accuracy of the method is dependent on the applicability of the constitutive model used in the inverse FEA, hence four potential material models: viscoelastic, viscoelastic–viscoplastic, nonlinear viscoelastic and nonlinear viscoelastic–viscoplastic were evaluated, with the latter enabling the best fit to experimental data. Significant changes in material properties were seen in the depth direction of the 3DP sample, which could be linked to the degree of cross-linking within the material, a feature inherent in a UV-cured layer-by-layer construction method. It is proposed that the method is a powerful tool in the analysis of manufacturing processes with potential spatial property variation that will also enable the accurate prediction of final manufactured part performance. PMID:26730216

  4. Spatially adaptive stochastic methods for fluid–structure interactions subject to thermal fluctuations in domains with complex geometries

    SciTech Connect

    Plunkett, Pat; Hu, Jonathan; Siefert, Christopher; Atzberger, Paul J.

    2014-11-15

    We develop stochastic mixed finite element methods for spatially adaptive simulations of fluid–structure interactions when subject to thermal fluctuations. To account for thermal fluctuations, we introduce a discrete fluctuation–dissipation balance condition to develop compatible stochastic driving fields for our discretization. We perform analysis that shows our condition is sufficient to ensure results consistent with statistical mechanics. We show the Gibbs–Boltzmann distribution is invariant under the stochastic dynamics of the semi-discretization. To generate efficiently the required stochastic driving fields, we develop a Gibbs sampler based on iterative methods and multigrid to generate fields with O(N) computational complexity. Our stochastic methods provide an alternative to uniform discretizations on periodic domains that rely on Fast Fourier Transforms. To demonstrate in practice our stochastic computational methods, we investigate within channel geometries having internal obstacles and no-slip walls how the mobility/diffusivity of particles depends on location. Our methods extend the applicability of fluctuating hydrodynamic approaches by allowing for spatially adaptive resolution of the mechanics and for domains that have complex geometries relevant in many applications.

  5. Spatially adaptive stochastic methods for fluid-structure interactions subject to thermal fluctuations in domains with complex geometries

    SciTech Connect

    Plunkett, Pat; Hu, Jonathan; Siefert, Christopher; Atzberger, Paul J.

    2014-08-07

    We develop stochastic mixed finite element methods for spatially adaptive simulations of fluid–structure interactions when subject to thermal fluctuations. To account for thermal fluctuations, we introduce a discrete fluctuation–dissipation balance condition to develop compatible stochastic driving fields for our discretization. We also perform analysis that shows our condition is sufficient to ensure results consistent with statistical mechanics. We show the Gibbs–Boltzmann distribution is invariant under the stochastic dynamics of the semi-discretization. To generate efficiently the required stochastic driving fields, we develop a Gibbs sampler based on iterative methods and multigrid to generate fields with O(N) computational complexity. Our stochastic methods provide an alternative to uniform discretizations on periodic domains that rely on Fast Fourier Transforms. To demonstrate in practice our stochastic computational methods, we investigate within channel geometries having internal obstacles and no-slip walls how the mobility/diffusivity of particles depends on location. Furthermore, our methods extend the applicability of fluctuating hydrodynamic approaches by allowing for spatially adaptive resolution of the mechanics and for domains that have complex geometries relevant in many applications.

  6. Model-Dependent Spatial Skill in Pseudoproxy Experiments Testing Climate Field Reconstruction Methods for the Common Era

    NASA Astrophysics Data System (ADS)

    Smerdon, Jason; Coats, Sloan; Ault, Toby

    2015-04-01

    The spatial skill of four climate field reconstruction (CFR) methods is investigated using pseudoproxy experiments (PPEs) based on five Last Millennium (LM) and historical simulations from the Coupled and Paleo Model Intercomparison Projects Phases 5 and 3 (CMIP5/PMIP3) data archives. These simulations are used for the first time in a PPE context, the pseudoproxy frameworks of which are constructed to test a recently assembled multiproxy network and multiple CFR techniques. The experiments confirm earlier findings demonstrating consistent methodological performance across all of the employed methods and spatially dependent reconstruction errors in the derived CFRs. Spectral biases in the reconstructed fields demonstrate that reconstruction methods can alone alter the ratio of spectral power at all locations in the field, independent of whether there are spectral biases inherent in the underlying proxy series. The patterns of spectral biases are model dependent and indicate the potential for regions in the derived CFRs to be biased by changes in either low or high-frequency spectral power. CFR methods are also shown to alter the pattern of mean differences in the tropical Pacific during the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA), with some model experiments indicating that CFR methodologies enhance the statistical likelihood of achieving a larger mean difference between the MCA and LIA in the region. All of the characteristics of reconstruction performance are model dependent, indicating that CFR methods must be evaluated across multiple models and that conclusions from PPEs should be carefully connected to the spatial statistics of real-world climatic fields.

  7. Temporal and spatial PM10 concentration distribution using an inverse distance weighted method in Klang Valley, Malaysia

    NASA Astrophysics Data System (ADS)

    Tarmizi, S. N. M.; Asmat, A.; Sumari, S. M.

    2014-02-01

    PM10 is one of the air contaminants that can be harmful to human health. Meteorological factors and changes of monsoon season may affect the distribution of these particles. The objective of this study is to determine the temporal and spatial particulate matter (PM10) concentration distribution in Klang Valley, Malaysia by using the Inverse Distance Weighted (IDW) method at different monsoon season and meteorological conditions. PM10 and meteorological data were obtained from the Malaysian Department of Environment (DOE). Particles distribution data were added to the geographic database on a seasonal basis. Temporal and spatial patterns of PM10 concentration distribution were determined by using ArcGIS 9.3. The higher PM10 concentrations are observed during Southwest monsoon season. The values are lower during the Northeast monsoon season. Different monsoon seasons show different meteorological conditions that effect PM10 distribution.

  8. A method for the selection of relevant pattern indices for monitoring of spatial forest cover pattern at a regional scale

    NASA Astrophysics Data System (ADS)

    De Clercq, Eva M.; Vandemoortele, Femke; De Wulf, Robert R.

    2006-06-01

    When signing Agenda 21, several countries agreed to monitor the status of forests to ensure their sustainable use. For reporting on the change in spatial forest cover pattern on a regional scale, pattern metrics are widely used. These indices are not often thoroughly evaluated as to their sensitivity to remote sensing data characteristics. Hence, one would not know whether the change in the metric values was due to actual landscape pattern changes or to characteristic variation of multitemporal remote sensing data. The objective of this study is to empirically test an array of pattern metrics for the monitoring of spatial forest cover. Different user requirements are used as point of departure. This proved to be a straightforward method for selecting relevant pattern indices. We strongly encourage the systematic screening of these indices prior to use in order to get a deeper understanding of the results obtained by them.

  9. Measurement of wavefront distortions by the method of aperture sounding with spatially separated channels

    SciTech Connect

    Prilepskiy, Boris V; Alikhanov, Alexey N; Berchenko, Evgeniy A; Kiselev, Vladimir Yu; Narusbek, Ernest A; Filatov, Aleksander S

    2005-08-31

    Features of the formation of signals in wavefront sensors with the single-frequency light wave phase modulation and spatial separation of control channels are considered. Analysis is performed for sensors in which phase modulation is governed by a controlled element located in the pupil of the optical system of a sensor or in the focal plane of the objective of this system. Peculiarities of the signal formation for a tilted wavefront are considered separately for internal points of the exit pupil in the case of light wave phase modulation in the pupil. It is shown that a signal at the modulation frequency in these wavefront sensors for points located far from the pupil boundaries is determined by the wavefront curvature. (laser applications and other topics in quantum electronics)

  10. On the Spatial and Temporal Accuracy of Overset Grid Methods for Moving Body Problems

    NASA Technical Reports Server (NTRS)

    Meakin, Robert L.

    1996-01-01

    A study of numerical attributes peculiar to an overset grid approach to unsteady aerodynamics prediction is presented. Attention is focused on the effect of spatial error associated with interpolation of intergrid boundary conditions and temporal error associated with explicit update of intergrid boundary points on overall solution accuracy. A set of numerical experiments are used to verify whether or not the use of simple interpolation for intergrid boundary conditions degrades the formal accuracy of a conventional second-order flow solver, and to quantify the error associated with explicit updating of intergrid boundary points. Test conditions correspond to the transonic regime. The validity of the numerical results presented here are established by comparison with existing numerical results of documented accuracy, and by direct comparison with experimental results.

  11. Review of Methods for Determining the Spatial Resolution of Uav Sensors

    NASA Astrophysics Data System (ADS)

    Orych, A.

    2015-08-01

    The ground resolved distance (GRD) of an imaging sensor, i.e. the size of the smallest element distinguishable on acquired imagery, is one of the most important sensor quality assessment factors, as it is directly linked to the amount of information that can be derived from the end product. The paper is a review of a wide variety of calibration targets used for determining the spatial resolution of remote sensing sensors. The author provides a description of calibration targets used historically and then moves on to high-frequency targets used for high-resolution remote sensing imaging equipment. As analysis is made which of these types of targets are best suited for UAV sensors, taking into account parameters very specific to UAVs: frame size, small GSD values and low flight stability.

  12. Two-Dimensional Planar Lightwave Circuit Integrated Spatial Filter Array and Method of Use Thereof

    NASA Technical Reports Server (NTRS)

    Ai, Jun (Inventor); Dimov, Fedor (Inventor)

    2015-01-01

    A large coherent two-dimensional (2D) spatial filter array (SFA), 30 by 30 or larger, is produced by coupling a 2D planar lightwave circuit (PLC) array with a pair of lenslet arrays at the input and output side. The 2D PLC array is produced by stacking a plurality of chips, each chip with a plural number of straight PLC waveguides. A pupil array is coated onto the focal plane of the lenslet array. The PLC waveguides are produced by deposition of a plural number of silica layers on the silicon wafer, followed by photolithography and reactive ion etching (RIE) processes. A plural number of mode filters are included in the silica-on-silicon waveguide such that the PLC waveguide is transparent to the fundamental mode but higher order modes are attenuated by 40 dB or more.

  13. A multiple-direction Trefftz method for solving the multi-dimensional wave equation in an arbitrary spatial domain

    NASA Astrophysics Data System (ADS)

    Liu, Chein-Shan; Kuo, Chung-Lun

    2016-09-01

    In this paper we first express the wave equation in terms of the Minkowskian polar coordinates and generate a set of complete hyperbolic type Trefftz bases: rk cosh ⁡ (kθ) and rk sinh ⁡ (kθ), which are further transformed to wave polynomials as the trial solution bases for the one-dimensional wave equation. In order to stably solve the wave propagation problems long-term we develop a multiple-scale Trefftz method (MSTM), of which the scales are determined a priori by the collocation points. Then we derive a very simple method of multi-dimensional wave polynomials, equipped with different spatial directions which being the normalized wavenumber vectors, as the polynomial Trefftz bases for solving the multi-dimensional wave equations, which is named a multiple-direction Trefftz method (MDTM). Several numerical examples of two- and three-dimensional wave equations demonstrate that the present method is efficient and stable.

  14. Groundwater modelling: Towards an estimation of the acceleration factors of iterative methods via an analysis of the transmissivity spatial variability

    NASA Astrophysics Data System (ADS)

    Benali, Abdelmajid

    2013-01-01

    When running a groundwater flow model, a recurrent and seemingly subsidiary question arises at the starting step of computations: what value of acceleration parameter do we need to optimize the numerical solver? A method is proposed to provide a practical estimate of the optimal acceleration parameter via a geostatistical analysis of the spatial variability of the logarithm of the transmissivity field Y. The background of the approach is illustrated on the successive over-relaxation method (SOR) used, either as a stand-alone solver, or as a symmetric preconditioner (SSOR) to the gradient conjugate method, or as a smoother in multigrid methods. It shows that this optimum acceleration factor is a function of the standard deviation and the correlation length of Y. This provides an easy-to-use heuristic procedure to estimate the acceleration factors, which could even be incorporated in the software package. A case study illustrates the steps needed to perform this estimation.

  15. Mapping of the SecA signal peptide binding site and dimeric interface by using the substituted cysteine accessibility method.

    PubMed

    Bhanu, Meera K; Zhao, Ping; Kendall, Debra A

    2013-10-01

    SecA is an ATPase nanomotor critical for bacterial secretory protein translocation. Secretory proteins carry an amino-terminal signal peptide that is recognized and bound by SecA followed by its transfer across the SecYEG translocon. While this process is crucial for the onset of translocation, exactly where the signal peptide interacts with SecA is unclear. SecA protomers also interact among themselves to form dimers in solution, yet the oligomeric interface and the residues involved in dimerization are unknown. To address these issues, we utilized the substituted cysteine accessibility method (SCAM); we generated a library of 23 monocysteine SecA mutants and probed for the accessibility of each mutant cysteine to maleimide-(polyethylene glycol)2-biotin (MPB), a sulfhydryl-labeling reagent, both in the presence and absence of a signal peptide. Dramatic differences in MPB labeling were observed, with a select few mutants located at the preprotein cross-linking domain (PPXD), the helical wing domain (HWD), and the helical scaffold domain (HSD), indicating that the signal peptide binds at the groove formed between these three domains. The exposure of this binding site is varied under different conditions and could therefore provide an ideal mechanism for preprotein transfer into the translocon. We also identified residues G793, A795, K797, and D798 located at the two-helix finger of the HSD to be involved in dimerization. Adenosine-5'-(γ-thio)-triphosphate (ATPγS) alone and, more extensively, in conjunction with lipids and signal peptides strongly favored dimer dissociation, while ADP supports dimerization. This study provides key insight into the structure-function relationships of SecA preprotein binding and dimer dissociation. PMID:23935053

  16. A numerical method to optimise the spatial dose distribution in carbon ion radiotherapy planning.

    PubMed

    Grzanka, L; Korcyl, M; Olko, P; Waligorski, M P R

    2015-09-01

    The authors describe a numerical algorithm to optimise the entrance spectra of a composition of pristine carbon ion beams which delivers a pre-assumed dose-depth profile over a given depth range within the spread-out Bragg peak. The physical beam transport model is based on tabularised data generated using the SHIELD-HIT10A Monte-Carlo code. Depth-dose profile optimisation is achieved by minimising the deviation from the pre-assumed profile evaluated on a regular grid of points over a given depth range. This multi-dimensional minimisation problem is solved using the L-BFGS-B algorithm, with parallel processing support. Another multi-dimensional interpolation algorithm is used to calculate at given beam depths the cumulative energy-fluence spectra for primary and secondary ions in the optimised beam composition. Knowledge of such energy-fluence spectra for each ion is required by the mixed-field calculation of Katz's cellular Track Structure Theory (TST) that predicts the resulting depth-survival profile. The optimisation algorithm and the TST mixed-field calculation are essential tools in the development of a one-dimensional kernel of a carbon ion therapy planning system. All codes used in the work are generally accessible within the libamtrack open source platform. PMID:25948835

  17. Experimental research of methods for clustering and selecting image fragments using spatial invariant equivalent models

    NASA Astrophysics Data System (ADS)

    Krasilenko, Vladimir G.; Lazarev, Alexander A.; Nikitovich, Diana V.

    2014-08-01

    In the paper, we show that the nonlinear spatial non-linear equivalency functions on the basis of continuous logic equivalence (nonequivalence) operations have better discriminatory properties for comparing images. Further, using the equivalent model of multiport neural networks and associative memory, (including matrix-matrix and matrix-tensor with adaptive-weighted correlation, multi-port neural-net auto-associative and hetero-associative memory (MP NN AAM and HAM ) and the proposed architecture based on them, we show how we can modify these models and architectures for space-invariant associative recognition and clustering (high performance parallel clustering processing) images. We consider possible implementations of 2D image classifiers, devices for partitioning image fragments into clusters and their architectures. The main base unit of such architectures is a matrix-matrix or matrix-tensor equivalentor, which can be implemented on the basis of two traditional correlators. We show that the classifiers based on the equivalency paradigm and optoelectronic architectures with space-time integration and parallel-serial 2D images processing have advantages such as increased memory capacity (more than ten times of the number of neurons!), High performance in different modes . We present the results of associative significant dimension (128x128, 610x340) image recognition - renewal modeling. It will be shown that these models are capable to recognize images with a significant percentage (20- 30%) damaged pixels. The experimental results show that such models can be successfully used for auto-and heteroassociative pattern recognition. We show simulation results of using these modifications for clustering and learning models and algorithms for cluster analysis of specific images and divide them into categories of the array. Show example of a cluster division of image fragments, letters and graphics for clusters with simultaneous formation of the outputweighted spatial

  18. Structure having spatially separated photo-excitable electron-hole pairs and method of manufacturing same

    DOEpatents

    Liang, Yong [Richland, WA; Daschbach, John L [Richland, WA; Su, Yali [Richland, WA; Chambers, Scott A [Kennewick, WA

    2003-03-18

    A method for producing quantum dots. The method includes cleaning an oxide substrate and separately cleaning a metal source. The substrate is then heated and exposed to the source in an oxygen environment. This causes metal oxide quantum dots to form on the surface of the substrate.

  19. Structure having spatially separated photo-excitable electron-hole pairs and method of manufacturing same

    DOEpatents

    Liang, Yong; Daschbach, John L.; Su, Yali; Chambers, Scott A.

    2006-08-22

    A method for producing quantum dots. The method includes cleaning an oxide substrate and separately cleaning a metal source. The substrate is then heated and exposed to the source in an oxygen environment. This causes metal oxide quantum dots to form on the surface of the substrate.

  20. Access to a polymerase chain reaction assay method targeting 13 respiratory viruses can reduce antibiotics: a randomised, controlled trial

    PubMed Central

    2011-01-01

    Background Viral respiratory infections are common worldwide and range from completely benign disease to life-threatening illness. Symptoms can be unspecific, and an etiologic diagnosis is rarely established because of a lack of suitable diagnostic tools. Improper use of antibiotics is common in this setting, which is detrimental in light of the development of bacterial resistance. It has been suggested that the use of diagnostic tests could reduce antibiotic prescription rates. The objective of this study was to evaluate whether access to a multiplex polymerase chain reaction (PCR) assay panel for etiologic diagnosis of acute respiratory tract infections (ARTIs) would have an impact on antibiotic prescription rate in primary care clinical settings. Methods Adult patients with symptoms of ARTI were prospectively included. Nasopharyngeal and throat swabs were analysed by using a multiplex real-time PCR method targeting thirteen viruses and two bacteria. Patients were recruited at 12 outpatient units from October 2006 through April 2009, and samples were collected on the day of inclusion (initial visit) and after 10 days (follow-up visit). Patients were randomised in an open-label treatment protocol to receive a rapid or delayed result (on the following day or after eight to twelve days). The primary outcome measure was the antibiotic prescription rate at the initial visit, and the secondary outcome was the total antibiotic prescription rate during the study period. Results A total sample of 447 patients was randomised. Forty-one were excluded, leaving 406 patients for analysis. In the group of patients randomised for a rapid result, 4.5% (9 of 202) of patients received antibiotics at the initial visit, compared to 12.3% (25 of 204) (P = 0.005) of patients in the delayed result group. At follow-up, there was no significant difference between the groups: 13.9% (28 of 202) in the rapid result group and 17.2% (35 of 204) in the delayed result group (P = 0

  1. Determining spatial variability of dry spells: a Markov-based method, applied to the Makanya catchment, Tanzania

    NASA Astrophysics Data System (ADS)

    Fischer, B. M. C.; Mul, M. L.; Savenije, H. H. G.

    2013-06-01

    With a growing world population and a trend towards more resource-intensive diets, pressure on land and water resources for food production will continue to increase in the coming decades. Large parts of the world rely on rainfed agriculture for their food security. In Africa, 90% of the food production is from rainfed agriculture, generally with low yields and a high risk of crop failure. One of the main reasons for crop failure is the occurrence of dry spells during the growing season. Key indicators are the critical dry spell duration and the probability of dry spell occurrence. In this paper a new Markov-based framework is presented to spatially map the length of dry spells for fixed probabilities of non-exceedance. The framework makes use of spatially varying Markov coefficients that are correlated to readily available spatial information such as elevation and distance to the sea. The dry spell map thus obtained is compared to the spatially variable critical dry spell duration, based on soil properties and crop water requirements, to assess the probability of crop failure in different locations. The results show that in the Makanya catchment the length of dry spell occurrence is highly variable in space, even over relatively short distances. In certain areas the probability of crop failure reaches levels that make rainfed agricultural unsustainable, even close to areas where currently rainfed agriculture is successfully being practised. This method can be used to identify regions that are vulnerable to dry spells and, subsequently, to develop strategies for supplementary irrigation or rainwater harvesting.

  2. Using the Electromagnetic Induction Method to Connect Spatial Vegetation Distributions with Soil Water and Salinity Dynamics on Steppe Grassland

    NASA Astrophysics Data System (ADS)

    Jiang, Z.; Li, X.; Wu, H.

    2014-12-01

    In arid and semi-arid areas, plant growth and productivity are obviously affected by soil water and salinity. But it is not easy to acquire the spatial and temporal dynamics of soil water and salinity by traditional field methods because of the heterogeneity in their patterns. Electromagnetic induction (EMI), for its rapid character, can provide a useful way to solve this problem. Grassland dominated by Achnatherum splendens is an important ecosystem near the Qinghai-Lake watershed on the Qinghai-Tibet Plateau in northwestern China. EMI surveys were conducted for electrical conductivity (ECa) at an intermediate habitat scale (a 60×60 m experimental area) of A. splendens steppe for 18 times (one day only for one time) during the 2013 growing season. And twenty sampling points were established for the collection of soil samples for soil water and salinity, which were used for calibration of ECa. In addition, plant species, biomass and spatial patterns of vegetation were also sampled. The results showed that ECa maps exhibited distinctly spatial differences because of variations in soil moisture. And soil water was the main factor to drive salinity patterns, which in turn affected ECa values. Moreover, soil water and salinity could explain 82.8% of ECa changes due to there was a significant correlation (P<0.01) between ECa, soil water and salinity. Furthermore, with higher ECa values closer to A. splendens patches at the experimental site, patterns of ECa images showed clearly temporal stability, which were extremely corresponding with the spatial pattern of vegetation. A. splendens patches that accumulated infiltrating water and salinity and thus changed long-term soil properties, which were considered as "reservoirs" and were deemed responsible for the temporal stability of ECa images. Hence, EMI could be an indicator to locate areas of decreasing or increasing of water and to reveal soil water and salinity dynamics through repeated ECa surveys.

  3. Evaluating Medical Marijuana Dispensary Policies: Spatial Methods for the Study of Environmentally-Based Interventions

    PubMed Central

    Freisthler, Bridget; Kepple, Nancy J.; Sims, Revel; Martin, Scott E.

    2013-01-01

    In 1996, California was the first state to pass a Compassionate Use Act allowing for the legal use of marijuana for medical purposes. Here we review several current policy and land use environmental interventions designed to limit problems related to the influx of medical marijuana dispensaries across California cities. Then we discuss the special challenges, solutions, and techniques used for studying the effects of these place-based policies. Finally, we present some of the advanced spatial analytic techniques that can be used to evaluate the effectiveness of environmental interventions, such as those related to reducing problems associated with the proliferation of medical marijuana dispensaries. Further, using data from a premise survey of all the dispensaries in Sacramento, this study will examine what characteristics and practices of these dispensaries are related to crime within varying distances from the dispensaries (e.g., 100, 250, 500, and 1000 feet). We find that some security measures, such as security cameras and having a door man outside, implemented by medical marijuana dispensary owners might be effective at reducing crime within the immediate vicinity of the dispensaries. PMID:22821130

  4. Spatial stochastic modeling of intracellular Ca2+ dynamics using two-regime methods

    NASA Astrophysics Data System (ADS)

    Dobramysl, Ulrich; Robinson, Martin; Erban, Radek

    2014-03-01

    The signaling pathways in many cell types depend on the controlled release of calcium ions from the endoplasmatic reticulum (ER) into the cytoplasm, via clusters of inisitol triphosphate (IP3) receptor channels. At low concentrations, Ca2+ ions facilitate channel activation, while acting as inhibitory agents at high concentrations. An activation event causes the opening of other channels in a cluster, resulting in a calcium puff. We simulate calcium ion dynamics using a recently-developed hybrid two-regime technique, wherein the positions of calcium ions in the vicinity of a channel cluster are tracked by employing an off-lattice Brownian dynamics algorithm. An efficient compartment-based algorithm is used in the remainder of the computational domain to correctly capture the diffusive spread of ions. We characterize calcium puffs via the distributions of inter-puff times and amplitudes and investigate the influence of diffusive noise on the puff characteristics by comparing our results with data obtained from an effective non-spatial model. The research leading to these results has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement no. 239870.

  5. [Research on spatially modulated Fourier transform imaging spectrometer data processing method].

    PubMed

    Huang, Min; Xiangli, Bin; Lü, Qun-Bo; Zhou, Jin-Song; Jing, Juan-Juan; Cui, Yan

    2010-03-01

    Fourier transform imaging spectrometer is a new technic, and has been developed very rapidly in nearly ten years. The data catched by Fourier transform imaging spectrometer is indirect data, can not be used by user, and need to be processed by various approaches, including data pretreatment, apodization, phase correction, FFT, and spectral radicalization calibration. No paper so far has been found roundly to introduce this method. In the present paper, the author will give an effective method to process the interfering data to spectral data, and with this method we can obtain good result. PMID:20496726

  6. INTEGRATION OF SPATIAL DATA: METHODS EVALUATION WITH REGARD TO DATA ISSUES AND ASSESSMENT QUESTIONS

    EPA Science Inventory

    EPA's Regional Vulnerability Assessment (REVA) Program is developing and demonstrating approaches to assess current and future environmental vulnerabilities at a regional scale. An initial effort within this research program has been to develop and evaluate methods to synthesize ...

  7. A method to visualize the evolution of multiple interacting spatial systems

    NASA Astrophysics Data System (ADS)

    Heitzler, Magnus; Hackl, Jürgen; Adey, Bryan T.; Iosifescu-Enescu, Ionut; Lam, Juan Carlos; Hurni, Lorenz

    2016-07-01

    Integrated modeling approaches are being increasingly used to simulate the behavior of, and the interaction between, several interdependent systems. They are becoming more and more important in many fields, including, but not being limited to, civil engineering, hydrology and climate impact research. It is beneficial when using these approaches to be able to visualize both, the intermediary and final results of scenario-based analyses that are conducted in both, space and time. This requires appropriate visualization techniques that enable to efficiently navigate between multiple such scenarios. In recent years, several innovative visualization techniques have been developed that allow for such navigation purposes. These techniques, however, are limited to the representation of one system at a time. Improvements are possible with respect to the ability to visualize the results related to multiple scenarios for multiple interdependent spatio-temporal systems. To address this issue, existing multi-scenario navigation techniques based on small multiples and line graphs are extended by multiple system representations and inter-system impact representations. This not only allows to understand the evolution of the systems under consideration but also eases identifying events where one system influences another system significantly. In addition, the concept of selective branching is described that allows to remove otherwise redundant information from the visualization by considering the logical and temporal dependencies between these systems. This visualization technique is applied to a risk assessment methodology that allows to determine how different environmental systems (i.e. precipitation, flooding, and landslides) influence each other as well as how their impact on civil infrastructure affects society. The results of this work are concepts for improved visualization techniques for multiple interacting spatial systems. The successful validation with domain experts of

  8. A new method for spatially selective, non-invasive activation of neurons: concept and computer simulation.

    PubMed

    Konings, Maurits K

    2007-01-01

    Currently available non-invasive neurostimulation devices, using skin electrodes or externally applied magnetic coils, are not capable of producing a local stimulation maximum deep inside a homogeneous conductor, because of a fundamental limitation inherent to the Laplace equation. In this paper, a new neurostimulation method (the DeepFocus method) is presented, which avoids this limitation by using an indirect method of producing electric currents inside tissues: First, cylinder-shaped ferromagnetic rotating disks of non-permanent magnetic material are placed near the skin and magnetized by a non-rotating magnetic coil. Each of the disks rotates at high speed around its own axis of symmetry, thus producing a purely electric Lorentz force field having a non-zero divergence outside the disk, and therefore giving rise to charge accumulations inside the tissues. Subsequently, the magnetic field is switched off suddenly, causing a re-distribution of charge, and hence short-lived electrical currents, which can be used to activate neurons. Two magnet configurations are presented in this paper, and analyzed by computer simulation, showing that the DeepFocus method produces a maximum current density (the 'focus') deep inside the conducting body. The field strength thus created in the focus (7.9 V/m) is strong enough to activate thick myelinated fibers, but can be kept below the threshold for C-fibers, which makes the new method a possible tool for pain mitigation by targeted neurostimulation. PMID:17186214

  9. Comparison of deterministic and stochastic methods to predict spatial variation of groundwater depth

    NASA Astrophysics Data System (ADS)

    Adhikary, Partha Pratim; Dash, Ch. Jyotiprava

    2014-11-01

    Accurate and reliable interpolation of groundwater depth over a region is a pre-requisite for efficient planning and management of water resources. The performance of two deterministic, such as inverse distance weighting (IDW) and radial basis function (RBF) and two stochastic, i.e., ordinary kriging (OK) and universal kriging (UK) interpolation methods was compared to predict spatio-temporal variation of groundwater depth. Pre- and post-monsoon groundwater level data for the year 2006 from 110 different locations over Delhi were used. Analyses revealed that OK and UK methods outperformed the IDW method, and UK performed better than OK. RBF also performed better than IDW and OK. IDW and RBF methods slightly underestimated and both the kriging methods slightly overestimated the prediction of water table depth. OK, RBF and UK yielded 27.52, 27.66 and 51.11 % lower RMSE, 27.49, 35.34 and 51.28 % lower MRE, and 14.21, 16.12 and 21.36 % higher R 2 over IDW. The isodepth-area curves indicated the possibility of exploitation of groundwater up to a depth of 20 m.

  10. Method for estimating spatially variable seepage loss and hydraulic conductivity in intermittent and ephemeral streams

    USGS Publications Warehouse

    Niswonger, R.G.; Prudic, D.E.; Fogg, G.E.; Stonestrom, D.A.; Buckland, E.M.

    2008-01-01

    A method is presented for estimating seepage loss and streambed hydraulic conductivity along intermittent and ephemeral streams using streamflow front velocities in initially dry channels. The method uses the kinematic wave equation for routing streamflow in channels coupled to Philip's equation for infiltration. The coupled model considers variations in seepage loss both across and along the channel. Water redistribution in the unsaturated zone is also represented in the model. Sensitivity of the streamflow front velocity to parameters used for calculating seepage loss and for routing streamflow shows that the streambed hydraulic conductivity has the greatest sensitivity for moderate to large seepage loss rates. Channel roughness, geometry, and slope are most important for low seepage loss rates; however, streambed hydraulic conductivity is still important for values greater than 0.008 m/d. Two example applications are presented to demonstrate the utility of the method. Copyright 2008 by the American Geophysical Union.

  11. Spatial homogenization methods for pin-by-pin neutron transport calculations

    NASA Astrophysics Data System (ADS)

    Kozlowski, Tomasz

    For practical reactor core applications low-order transport approximations such as SP3 have been shown to provide sufficient accuracy for both static and transient calculations with considerably less computational expense than the discrete ordinate or the full spherical harmonics methods. These methods have been applied in several core simulators where homogenization was performed at the level of the pin cell. One of the principal problems has been to recover the error introduced by pin-cell homogenization. Two basic approaches to treat pin-cell homogenization error have been proposed: Superhomogenization (SPH) factors and Pin-Cell Discontinuity Factors (PDF). These methods are based on well established Equivalence Theory and Generalized Equivalence Theory to generate appropriate group constants. These methods are able to treat all sources of error together, allowing even few-group diffusion with one mesh per cell to reproduce the reference solution. A detailed investigation and consistent comparison of both homogenization techniques showed potential of PDF approach to improve accuracy of core calculation, but also reveal its limitation. In principle, the method is applicable only for the boundary conditions at which it was created, i.e. for boundary conditions considered during the homogenization process---normally zero current. Therefore, there exists a need to improve this method, making it more general and environment independent. The goal of proposed general homogenization technique is to create a function that is able to correctly predict the appropriate correction factor with only homogeneous information available, i.e. a function based on heterogeneous solution that could approximate PDFs using homogeneous solution. It has been shown that the PDF can be well approximated by least-square polynomial fit of non-dimensional heterogeneous solution and later used for PDF prediction using homogeneous solution. This shows a promise for PDF prediction for off

  12. Two-wavelength method for endoscopic shape measurement by spatial phase-shifting speckle-interferometry.

    PubMed

    Kandulla, Jochen; Kemper, Björn; Knoche, Sabine; von Bally, Gert

    2004-10-10

    A two-wavelength method for endoscopic topography reconstruction is introduced that can be applied to out-of-plane sensitive electronic-speckle-pattern interferometry systems based on rigid endoscope imaging systems. The surface measurement is performed by detection of the phase-difference distribution affected by a change in the applied laser wavelength. Furthermore, the off-axis endoscopic illumination geometry is taken into account by an approximation. Experimental results of the characterization of the endoscopic surface reconstruction technique and the measurement accuracy obtained are described and discussed. Finally, the applicability of the method is demonstrated with results from the topographic reconstruction of a free-form surface. PMID:15508598

  13. A nonfitting method using a spatial sine window transform for inhomogeneous effective-diffusion measurements by FRAP.

    PubMed

    Orlova, Darya Y; Bártová, Eva; Maltsev, Valeri P; Kozubek, Stanislav; Chernyshev, Andrei V

    2011-01-19

    Determining averaged effective diffusion constants from experimental measurements of fluorescent proteins in an inhomogeneous medium in the presence of ligand-receptor interactions poses problems of analytical tractability. Here, we introduced a nonfitting method to evaluate the averaged effective diffusion coefficient of a region of interest (which may include a whole nucleus) by mathematical processing of the entire cellular two-dimensional spatial pattern of recovered fluorescence. Spatially and temporally resolved measurements of protein transport inside cells were obtained using the fluorescence recovery after photobleaching technique. Two-dimensional images of fluorescence patterns were collected by laser-scanning confocal microscopy. The method was demonstrated by applying it to an estimation of the mobility of green fluorescent protein-tagged heterochromatin protein 1 in the nuclei of living mouse embryonic fibroblasts. This approach does not require the mathematical solution of a corresponding system of diffusion-reaction equations that is typical of conventional fluorescence recovery after photobleaching data processing, and is most useful for investigating highly inhomogeneous areas, such as cell nuclei, which contain many protein foci and chromatin domains. PMID:21244847

  14. A Nonfitting Method Using a Spatial Sine Window Transform for Inhomogeneous Effective-Diffusion Measurements by FRAP

    PubMed Central

    Orlova, Darya Y.; Bártová, Eva; Maltsev, Valeri P.; Kozubek, Stanislav; Chernyshev, Andrei V.

    2011-01-01

    Determining averaged effective diffusion constants from experimental measurements of fluorescent proteins in an inhomogeneous medium in the presence of ligand-receptor interactions poses problems of analytical tractability. Here, we introduced a nonfitting method to evaluate the averaged effective diffusion coefficient of a region of interest (which may include a whole nucleus) by mathematical processing of the entire cellular two-dimensional spatial pattern of recovered fluorescence. Spatially and temporally resolved measurements of protein transport inside cells were obtained using the fluorescence recovery after photobleaching technique. Two-dimensional images of fluorescence patterns were collected by laser-scanning confocal microscopy. The method was demonstrated by applying it to an estimation of the mobility of green fluorescent protein-tagged heterochromatin protein 1 in the nuclei of living mouse embryonic fibroblasts. This approach does not require the mathematical solution of a corresponding system of diffusion-reaction equations that is typical of conventional fluorescence recovery after photobleaching data processing, and is most useful for investigating highly inhomogeneous areas, such as cell nuclei, which contain many protein foci and chromatin domains. PMID:21244847

  15. Novel Microbiological and Spatial Statistical Methods to Improve Strength of Epidemiological Evidence in a Community-Wide Waterborne Outbreak

    PubMed Central

    Jalava, Katri; Rintala, Hanna; Ollgren, Jukka; Maunula, Leena; Gomez-Alvarez, Vicente; Revez, Joana; Palander, Marja; Antikainen, Jenni; Kauppinen, Ari; Räsänen, Pia; Siponen, Sallamaari; Nyholm, Outi; Kyyhkynen, Aino; Hakkarainen, Sirpa; Merentie, Juhani; Pärnänen, Martti; Loginov, Raisa; Ryu, Hodon; Kuusi, Markku; Siitonen, Anja; Miettinen, Ilkka; Santo Domingo, Jorge W.; Hänninen, Marja-Liisa; Pitkänen, Tarja

    2014-01-01

    Failures in the drinking water distribution system cause gastrointestinal outbreaks with multiple pathogens. A water distribution pipe breakage caused a community-wide waterborne outbreak in Vuorela, Finland, July 2012. We investigated this outbreak with advanced epidemiological and microbiological methods. A total of 473/2931 inhabitants (16%) responded to a web-based questionnaire. Water and patient samples were subjected to analysis of multiple microbial targets, molecular typing and microbial community analysis. Spatial analysis on the water distribution network was done and we applied a spatial logistic regression model. The course of the illness was mild. Drinking untreated tap water from the defined outbreak area was significantly associated with illness (RR 5.6, 95% CI 1.9–16.4) increasing in a dose response manner. The closer a person lived to the water distribution breakage point, the higher the risk of becoming ill. Sapovirus, enterovirus, single Campylobacter jejuni and EHEC O157:H7 findings as well as virulence genes for EPEC, EAEC and EHEC pathogroups were detected by molecular or culture methods from the faecal samples of the patients. EPEC, EAEC and EHEC virulence genes and faecal indicator bacteria were also detected in water samples. Microbial community sequencing of contaminated tap water revealed abundance of Arcobacter species. The polyphasic approach improved the understanding of the source of the infections, and aided to define the extent and magnitude of this outbreak. PMID:25147923

  16. A novel method for detecting abrupt dynamic change based on the changing Hurst exponent of spatial images

    NASA Astrophysics Data System (ADS)

    He, Wen-Ping; Liu, Qun-Qun; Gu, Bin; Zhao, Shan-Shan

    2016-01-01

    The climate system is a classical spatiotemporal evolutionary dynamic system with spatiotemporal correlation characteristics. Based on this, two-dimensional detrended fluctuation analysis (TD-DFA) is used to estimate the Hurst exponent of two-dimensional images. Then, we monitored the change of the Hurst exponent of the images to identify an abrupt dynamic change. We tested the performance of this method with a coupled spatiotemporal dynamic model and found that it works well. The changes in the Hurst exponents of the spatial images are stable when there is no dynamic change in the system, but there will be a clear non-stationary change of the Hurst exponents; for example, the abrupt mean values change if the dynamics of the system change. Thus, the TD-DFA method is suitable for detecting an abrupt dynamic change from natural and artificial images. The spatial images of the NCEP reanalysis of the daily average temperature exhibited fractality. Based on this, we found three non-stationary changes in the Hurst exponents for the NCEP reanalysis of the daily average temperature or for the annual average temperature in the region (60°S-60°N). It can be concluded that the climate system may have incurred three dynamic changes since 1961 on decadal timescales, i.e., in approximately the mid-1970s, the mid-1980s, and between the late 1990s and the early 2000s.

  17. Science in the clouds: UAVs and cloud computing methods for spatial diffuse pollution risk assessment (Invited)

    NASA Astrophysics Data System (ADS)

    Reaney, S. M.

    2010-12-01

    The processes related to diffuse pollution can be understood within a 'source -> mobilisation -> pathway -> impact' framework. Recently our ability to monitor the impact section of this framework has significantly increased. This has been achieved through the measurement of flow and water quality (e.g. Nitrogen and Phosphorus) on a continuous 10 minute basis. However, our ability to observe and understand the 'source', 'mobilisation' and 'pathway' sections has not progressed at the same rate. This lack of information of the source term is due to the larger spatial areas involved and the difficulty in performing repeat surveys. Within an agricultural catchment, there are two key, temporally dynamic factors that affect the diffuse pollution export [source-mobilisation-pathway]: 1. vegetation cover and 2. agricultural management. These factors influence the amount of bare soil, vulnerable to erosion (source) and the creation of flow pathways, for example, due to tractor wheelings (tram lines). Information on these factors could be acquired through the use of satellite remote sensing or light aircraft based aerial photography. However, to acquire images on a fine temporal scale (monthly) there are significant cost and practical barriers (e.g. cloud cover). A potential solution to the problem could be the use of small semi- autonomous helicopters (UAV) and is the approach that has been investigated in this research. The UAV helicopter that has been used in this research is a Microdrones MD4-200 and is capable of autonomously flying a pre-programmed route and acquiring images at set locations at heights of up to 120 metres. The use of the pre-programmed routes enables the acquisition of repeat images at the same locations. These images contain information on the vegetation cover that can be extracted with the use of standard image processing techniques. However, the images also contain a large amount of implicit information that may help to explain water quality trends

  18. A new method of spatial analysis of irregularly spaced HLB data and biological implications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field data on intensity of plant diseases is very often irregularly spaced (i.e., there are varying amounts of distance between rows, ponds, voids, roads, houses, or other land areas). A new method of analysis, sometimes called second-generation wavelet analysis, can be used on this type of irregula...

  19. Novice Drafters' Spatial Visualization Development: Influence of Instructional Methods and Individual Learning Styles

    ERIC Educational Resources Information Center

    Scribner, Shauna A.; Anderson, Marcia A.

    2005-01-01

    According to Farrell and Kotrlik (2003), educators can become more effective teachers by assessing their students' preferred learning styles. This assessment can help in planning the curriculum and in selecting appropriate instructional methods. Thus, research is needed to determine if there is a link between students' learning styles and their…

  20. Open Access and beyond.

    PubMed

    Mathur, Shawn; Schmidt, Christian; Das, Chhaya; Tucker, Philip W

    2006-01-01

    Uncensored exchange of scientific results hastens progress. Open Access does not stop at the removal of price and permission barriers; still, censorship and reading disabilities, to name a few, hamper access to information. Here, we invite the scientific community and the public to discuss new methods to distribute, store and manage literature in order to achieve unfettered access to literature. PMID:16956402

  1. [Spatial-temporal evolution characterization of land subsidence by multi-temporal InSAR method and GIS technology].

    PubMed

    Chen, Bei-Bei; Gong, Hui-Li; Li, Xiao-Juan; Lei, Kun-Chao; Duan, Guang-Yao; Xie, Jin-Rong

    2014-04-01

    Long-term over-exploitation of underground resources, and static and dynamic load increase year by year influence the occurrence and development of regional land subsidence to a certain extent. Choosing 29 scenes Envisat ASAR images covering plain area of Beijing, China, the present paper used the multi-temporal InSAR method incorporating both persistent scatterer and small baseline approaches, and obtained monitoring information of regional land subsidence. Under different situation of space development and utilization, the authors chose five typical settlement areas; With classified information of land-use, multi-spectral remote sensing image, and geological data, and adopting GIS spatial analysis methods, the authors analyzed the time series evolution characteristics of uneven settlement. The comprehensive analysis results suggests that the complex situations of space development and utilization affect the trend of uneven settlement; the easier the situation of space development and utilization, the smaller the settlement gradient, and the less the uneven settlement trend. PMID:25007621

  2. Stochastic weighted particle methods for population balance equations with coagulation, fragmentation and spatial inhomogeneity

    NASA Astrophysics Data System (ADS)

    Lee, Kok Foong; Patterson, Robert I. A.; Wagner, Wolfgang; Kraft, Markus

    2015-12-01

    This paper introduces stochastic weighted particle algorithms for the solution of multi-compartment population balance equations. In particular, it presents a class of fragmentation weight transfer functions which are constructed such that the number of computational particles stays constant during fragmentation events. The weight transfer functions are constructed based on systems of weighted computational particles and each of it leads to a stochastic particle algorithm for the numerical treatment of population balance equations. Besides fragmentation, the algorithms also consider physical processes such as coagulation and the exchange of mass with the surroundings. The numerical properties of the algorithms are compared to the direct simulation algorithm and an existing method for the fragmentation of weighted particles. It is found that the new algorithms show better numerical performance over the two existing methods especially for systems with significant amount of large particles and high fragmentation rates.

  3. A systematic method for studying the spatial distribution of water molecules around nucleic acid bases.

    PubMed Central

    Schneider, B; Cohen, D M; Schleifer, L; Srinivasan, A R; Olson, W K; Berman, H M

    1993-01-01

    A new method to analyze the distribution of water molecules around the bases in DNA is presented. This method relies on the notion of a "hydrated building block," which represents the joint observed hydration around all bases of a particular type, in structures of a particular conformation type. The hydrated building blocks were constructed using atomic coordinates from 40 structures contained in the Nucleic Acid Database. Pseudoelectron densities were calculated for water molecules in each hydrated building block using standard crystallographic procedures. The electron densities were fitted to obtain "average building blocks," which represent bases with waters only at average or probable positions. Both types of building blocks were used to construct models of hydrated DNA oligomers. The essential features of the solvent structure around d(CGCGAATTCGCG)2 in the B form and d(CGCGCG)2 in the Z form were reproduced. Images FIGURE 4 FIGURE 5 PMID:8312469

  4. Endoscopic ultrasonography (EUS) as a method used in spatial localization of digestive tract tumors

    NASA Astrophysics Data System (ADS)

    Skrzywanek, Pawel; Sowier, Aleksander; Cysewska-Sobusiak, Anna R.

    2004-07-01

    The subject of the paper is devoted to a modern diagnostic method called the endoscopic ultrasonography (EUS) that is still not widely implemented in many countries. This method bases on two imaging techniques: videoendoscopy and ultrasonography, making possible effective aiding of diagnostics as well as evaluating possibilities of performing radical surgical therapy. Rotating USG probes enable acquiring images vertical to an axis for the round angle area. Small diameters and adequate frequencies of these microprobes make possible their deep penetration into such difficult sites as the biliary and pancreatic ducts. The EUS advantages are presented here on the basis of several examples of real minimally invasive interventions as well diagnostic procedures practiced by the authors. EUS has allowed precise diagnostics without disturbances occurring at conventional ultrasound imaging. The presented images concern EUS used for examination of different digestive tract diseases, including biliary and pancreatic ducts.

  5. Discrete ordinates methods in xy geometry with spatially varying angular discretization

    SciTech Connect

    Bal, G.; Warin, X.

    1997-10-01

    The efficiency of a new quadrature rule adapted to the numerical resolution of a neutron transport problem in xy geometry is presented based on the use of the discrete ordinates method for the angular variable. The purpose of introducing this quadrature rule is to couple two different angular discretizations used on two nonoverlapping subdomains, which is useful for performing local refinement. This coupling and some numerical results of source problems are presented.

  6. Environmental determinants of the spatial distribution of Mesocestoides spp. and sensitivity of flotation method for the diagnosis of mesocestoidosis.

    PubMed

    Széll, Z; Tolnai, Z; Sréter, T

    2015-09-15

    Mesocestoides spp. are zoonotic cestodes of wild and domesticated carnivores. Although the adult stages are relatively harmless intestinal parasites, the metacestode stages (tetrathyridia) can be responsible for life-threatening peritonitis and pleuritis in several species including dogs, cats, non-human primates and probably man. The aim of the present study was to reveal the spatial distribution pattern of Mesocestoides spp. in the most important final hosts, red foxes (Vulpes vulpes), to analyse the relationship of these patterns with landscape and climate by geographical information systems and to evaluate faecal flotation method for the detection of infection in the final host. Fox carcasses, representing 0.5% of the total fox population were randomly selected out of all the foxes of Hungary. The intestinal tract was examined by sedimentation and counting technique. The sensitivity of the flotation method was evaluated by the testing of the faecal samples of 180 foxes infected with Mesocestoides spp. The prevalence of infection was high in foxes (45.8%; 95% CI=41.0-50.6%), and the parasite was detected in all areas of Hungary. The high prevalence of the parasite in foxes suggests that the infection might also be common in outdoor dogs and cats. Mesocestoides infection could not be detected in any of the foxes by flotation method indicating that the sensitivity of the method is less than 0.6%. Therefore, almost all canine and feline infections remain undetected in the veterinary practice. Based on the statistical analysis, the altitude was the only determinant of the spatial distribution of Mesocestoides spp. indicating that infections in carnivores including dogs and cats can be expected mainly in midland regions (150-750 m above sea level). It might be attributed to the altitude-dependent species richness and abundance of the intermediate and final hosts of the parasite. PMID:26150263

  7. A method for spatially resolved local intracellular mechanochemical sensing and organelle manipulation.

    PubMed

    Shekhar, S; Cambi, A; Figdor, C G; Subramaniam, V; Kanger, J S

    2012-08-01

    Because both the chemical and mechanical properties of living cells play crucial functional roles, there is a strong need for biophysical methods to address these properties simultaneously. Here we present a novel (to our knowledge) approach to measure local intracellular micromechanical and chemical properties using a hybrid magnetic chemical biosensor. We coupled a fluorescent dye, which serves as a chemical sensor, to a magnetic particle that is used for measurement of the viscoelastic environment by studying the response of the particle to magnetic force pulses. As a demonstration of the potential of this approach, we applied the method to study the process of phagocytosis, wherein cytoskeletal reorganization occurs in parallel with acidification of the phagosome. During this process, we measured the shear modulus and viscosity of the phagosomal environment concurrently with the phagosomal pH. We found that it is possible to manipulate phagocytosis by stalling the centripetal movement of the phagosome using magnetic force. Our results suggest that preventing centripetal phagosomal transport delays the onset of acidification. To our knowledge, this is the first report of manipulation of intracellular phagosomal transport without interfering with the underlying motor proteins or cytoskeletal network through biochemical methods. PMID:22947855

  8. Landscape object-based analysis of wetland plant functional types: the effects of spatial scale, vegetation classes and classifier methods

    NASA Astrophysics Data System (ADS)

    Dronova, I.; Gong, P.; Wang, L.; Clinton, N.; Fu, W.; Qi, S.

    2011-12-01

    Remote sensing-based vegetation classifications representing plant function such as photosynthesis and productivity are challenging in wetlands with complex cover and difficult field access. Recent advances in object-based image analysis (OBIA) and machine-learning algorithms offer new classification tools; however, few comparisons of different algorithms and spatial scales have been discussed to date. We applied OBIA to delineate wetland plant functional types (PFTs) for Poyang Lake, the largest freshwater lake in China and Ramsar wetland conservation site, from 30-m Landsat TM scene at the peak of spring growing season. We targeted major PFTs (C3 grasses, C3 forbs and different types of C4 grasses and aquatic vegetation) that are both key players in system's biogeochemical cycles and critical providers of waterbird habitat. Classification results were compared among: a) several object segmentation scales (with average object sizes 900-9000 m2); b) several families of statistical classifiers (including Bayesian, Logistic, Neural Network, Decision Trees and Support Vector Machines) and c) two hierarchical levels of vegetation classification, a generalized 3-class set and more detailed 6-class set. We found that classification benefited from object-based approach which allowed including object shape, texture and context descriptors in classification. While a number of classifiers achieved high accuracy at the finest pixel-equivalent segmentation scale, the highest accuracies and best agreement among algorithms occurred at coarser object scales. No single classifier was consistently superior across all scales, although selected algorithms of Neural Network, Logistic and K-Nearest Neighbors families frequently provided the best discrimination of classes at different scales. The choice of vegetation categories also affected classification accuracy. The 6-class set allowed for higher individual class accuracies but lower overall accuracies than the 3-class set because

  9. Detecting spatial structures in throughfall data: the effect of extent, sample size, sampling design, and variogram estimation method

    NASA Astrophysics Data System (ADS)

    Voss, Sebastian; Zimmermann, Beate; Zimmermann, Alexander

    2016-04-01

    In the last three decades, an increasing number of studies analyzed spatial patterns in throughfall to investigate the consequences of rainfall redistribution for biogeochemical and hydrological processes in forests. In the majority of cases, variograms were used to characterize the spatial properties of the throughfall data. The estimation of the variogram from sample data requires an appropriate sampling scheme: most importantly, a large sample and an appropriate layout of sampling locations that often has to serve both variogram estimation and geostatistical prediction. While some recommendations on these aspects exist, they focus on Gaussian data and high ratios of the variogram range to the extent of the study area. However, many hydrological data, and throughfall data in particular, do not follow a Gaussian distribution. In this study, we examined the effect of extent, sample size, sampling design, and calculation methods on variogram estimation of throughfall data. For our investigation, we first generated non-Gaussian random fields based on throughfall data with heavy outliers. Subsequently, we sampled the fields with three extents (plots with edge lengths of 25 m, 50 m, and 100 m), four common sampling designs (two grid-based layouts, transect and random sampling), and five sample sizes (50, 100, 150, 200, 400). We then estimated the variogram parameters by method-of-moments and residual maximum likelihood. Our key findings are threefold. First, the choice of the extent has a substantial influence on the estimation of the variogram. A comparatively small ratio of the extent to the correlation length is beneficial for variogram estimation. Second, a combination of a minimum sample size of 150, a design that ensures the sampling of small distances and variogram estimation by residual maximum likelihood offers a good compromise between accuracy and efficiency. Third, studies relying on method-of-moments based variogram estimation may have to employ at least

  10. Thermal conductivity profile determination in proton-irradiated ZrC by spatial and frequency scanning thermal wave methods

    NASA Astrophysics Data System (ADS)

    Jensen, C.; Chirtoc, M.; Horny, N.; Antoniow, J. S.; Pron, H.; Ban, H.

    2013-10-01

    Using complementary thermal wave methods, the irradiation damaged region of zirconium carbide (ZrC) is characterized by quantifiably profiling the thermophysical property degradation. The ZrC sample was irradiated by a 2.6 MeV proton beam at 600 °C to a dose of 1.75 displacements per atom. Spatial scanning techniques including scanning thermal microscopy (SThM), lock-in infrared thermography (lock-in IRT), and photothermal radiometry (PTR) were used to directly map the in-depth profile of thermal conductivity on a cross section of the ZrC sample. The advantages and limitations of each system are discussed and compared, finding consistent results from all techniques. SThM provides the best resolution finding a very uniform thermal conductivity envelope in the damaged region measuring ˜52 ± 2 μm deep. Frequency-based scanning PTR provides quantification of the thermal parameters of the sample using the SThM measured profile to provide validation of a heating model. Measured irradiated and virgin thermal conductivities are found to be 11.9 ± 0.5 W m-1