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Sample records for spatial olap application

  1. Easier surveillance of climate-related health vulnerabilities through a Web-based spatial OLAP application

    PubMed Central

    Bernier, Eveline; Gosselin, Pierre; Badard, Thierry; Bédard, Yvan

    2009-01-01

    Background Climate change has a significant impact on population health. Population vulnerabilities depend on several determinants of different types, including biological, psychological, environmental, social and economic ones. Surveillance of climate-related health vulnerabilities must take into account these different factors, their interdependence, as well as their inherent spatial and temporal aspects on several scales, for informed analyses. Currently used technology includes commercial off-the-shelf Geographic Information Systems (GIS) and Database Management Systems with spatial extensions. It has been widely recognized that such OLTP (On-Line Transaction Processing) systems were not designed to support complex, multi-temporal and multi-scale analysis as required above. On-Line Analytical Processing (OLAP) is central to the field known as BI (Business Intelligence), a key field for such decision-support systems. In the last few years, we have seen a few projects that combine OLAP and GIS to improve spatio-temporal analysis and geographic knowledge discovery. This has given rise to SOLAP (Spatial OLAP) and a new research area. This paper presents how SOLAP and climate-related health vulnerability data were investigated and combined to facilitate surveillance. Results Based on recent spatial decision-support technologies, this paper presents a spatio-temporal web-based application that goes beyond GIS applications with regard to speed, ease of use, and interactive analysis capabilities. It supports the multi-scale exploration and analysis of integrated socio-economic, health and environmental geospatial data over several periods. This project was meant to validate the potential of recent technologies to contribute to a better understanding of the interactions between public health and climate change, and to facilitate future decision-making by public health agencies and municipalities in Canada and elsewhere. The project also aimed at integrating an initial

  2. Usability Evaluation of the Spatial OLAP Visualization and Analysis Tool (SOVAT)

    PubMed Central

    Scotch, Matthew; Parmanto, Bambang; Monaco, Valerie

    2015-01-01

    Increasingly sophisticated technologies, such as On-Line Analytical Processing (OLAP) and Geospatial Information Systems (GIS), are being leveraged for conducting community health assessments (CHA). Little is known about the usability of OLAP and GIS interfaces with respect to CHA. We conducted an iterative usability evaluation of the Spatial OLAP Visualization and Analysis Tool (SOVAT), a software application that combines OLAP and GIS. A total of nine graduate students and six community health researchers were asked to think-aloud while completing five CHA questions using SOVAT. The sessions were analyzed after every three participants and changes to the interface were made based on the findings. Measures included elapsed time, answers provided, erroneous actions, and satisfaction. Traditional OLAP interface features were poorly understood by participants and combined OLAP-GIS features needed to be better emphasized. The results suggest that the changes made to the SOVAT interface resulted in increases in both usability and user satisfaction. PMID:26613012

  3. A Conceptual Modeling Approach for OLAP Personalization

    NASA Astrophysics Data System (ADS)

    Garrigós, Irene; Pardillo, Jesús; Mazón, Jose-Norberto; Trujillo, Juan

    Data warehouses rely on multidimensional models in order to provide decision makers with appropriate structures to intuitively analyze data with OLAP technologies. However, data warehouses may be potentially large and multidimensional structures become increasingly complex to be understood at a glance. Even if a departmental data warehouse (also known as data mart) is used, these structures would be also too complex. As a consequence, acquiring the required information is more costly than expected and decision makers using OLAP tools may get frustrated. In this context, current approaches for data warehouse design are focused on deriving a unique OLAP schema for all analysts from their previously stated information requirements, which is not enough to lighten the complexity of the decision making process. To overcome this drawback, we argue for personalizing multidimensional models for OLAP technologies according to the continuously changing user characteristics, context, requirements and behaviour. In this paper, we present a novel approach to personalizing OLAP systems at the conceptual level based on the underlying multidimensional model of the data warehouse, a user model and a set of personalization rules. The great advantage of our approach is that a personalized OLAP schema is provided for each decision maker contributing to better satisfy their specific analysis needs. Finally, we show the applicability of our approach through a sample scenario based on our CASE tool for data warehouse development.

  4. CAMS: OLAPing Multidimensional Data Streams Efficiently

    NASA Astrophysics Data System (ADS)

    Cuzzocrea, Alfredo

    In the context of data stream research, taming the multidimensionality of real-life data streams in order to efficiently support OLAP analysis/mining tasks is a critical challenge. Inspired by this fundamental motivation, in this paper we introduce CAMS (C ube-based A cquisition model for M ultidimensional S treams), a model for efficiently OLAPing multidimensional data streams. CAMS combines a set of data stream processing methodologies, namely (i) the OLAP dimension flattening process, which allows us to obtain dimensionality reduction of multidimensional data streams, and (ii) the OLAP stream aggregation scheme, which aggregates data stream readings according to an OLAP-hierarchy-based membership approach. We complete our analytical contribution by means of experimental assessment and analysis of both the efficiency and the scalability of OLAPing capabilities of CAMS on synthetic multidimensional data streams. Both analytical and experimental results clearly connote CAMS as an enabling component for next-generation Data Stream Management Systems.

  5. The Composite OLAP-Object Data Model

    SciTech Connect

    Pourabbas, Elaheh; Shoshani, Arie

    2005-12-07

    In this paper, we define an OLAP-Object model that combines the main characteristics of OLAP and Object data models in order to achieve their functionalities in a common framework. We classify three different object classes: primitive, regular and composite. Then, we define a query language which uses the path concept in order to facilitate data navigation and data manipulation. The main feature of the proposed language is an anchor. It allows us to fix dynamically an object class (primitive, regular or composite) along the paths over the OLAP-Object data model for expressing queries. The queries can be formulated on objects, composite objects and combination of both. The power of the proposed query language is investigated through multiple query examples. The semantic of different clauses and syntax of the proposed language are investigated.

  6. Connecting traditional sciences with the OLAP and data mining paradigms

    NASA Astrophysics Data System (ADS)

    Guergachi, Aziz A.

    2003-03-01

    The paradigms of OLAP, multidimensional modeling and data mining have first emerged in the areas of market analysis and finance to address various needs of people working in these areas. Does this mean that they are useful and applicable in these areas only? Or, can they also be applicable in the other more traditional areas of science and engineering? What characterize the systems for which these paradigms are suitable? What are the goals of these paradigms? How do they relate to the traditional body of knowledge that has been developed throughout the centuries in the areas of mathematics, statistics, systems science and engineering? Where, how and to what extent can we leverage the conventional wisdom that has been accumulated in the aforementioned disciplines to develop a foundational basis for the above paradigms? The goal of this paper is to address these questions at the foundational level. We argue that the paradigms of OLAP, multidimensional modeling and data mining can also be applied successfully to complex engineering systems, such as membrane-based water/wastewater treatment plants, for example. We develop mathematically-based axiomatic definition of the concepts of 'dimension,' 'dimension level,' 'dimension hierarchy' and 'measure' using set theory and equivalence relations.

  7. Using data warehousing and OLAP in public health care.

    PubMed

    Hristovski, D; Rogac, M; Markota, M

    2000-01-01

    The paper describes the possibilities of using data warehousing and OLAP technologies in public health care in general and then our own experience with these technologies gained during the implementation of a data warehouse of outpatient data at the national level. Such a data warehouse serves as a basis for advanced decision support systems based on statistical, OLAP or data mining methods. We used OLAP to enable interactive exploration and analysis of the data. We found out that data warehousing and OLAP are suitable for the domain of public health and that they enable new analytical possibilities in addition to the traditional statistical approaches. PMID:11079907

  8. Examining the Impact of Culture and Human Elements on OLAP Tools Usefulness

    ERIC Educational Resources Information Center

    Sharoupim, Magdy S.

    2010-01-01

    The purpose of the present study was to examine the impact of culture and human-related elements on the On-line Analytical Processing (OLAP) usability in generating decision-making information. The use of OLAP technology has evolved rapidly and gained momentum, mainly due to the ability of OLAP tools to examine and query large amounts of data sets…

  9. View discovery in OLAP databases through statistical combinatorial optimization

    SciTech Connect

    Hengartner, Nick W; Burke, John; Critchlow, Terence; Joslyn, Cliff; Hogan, Emilie

    2009-01-01

    OnLine Analytical Processing (OLAP) is a relational database technology providing users with rapid access to summary, aggregated views of a single large database, and is widely recognized for knowledge representation and discovery in high-dimensional relational databases. OLAP technologies provide intuitive and graphical access to the massively complex set of possible summary views available in large relational (SQL) structured data repositories. The capability of OLAP database software systems to handle data complexity comes at a high price for analysts, presenting them a combinatorially vast space of views of a relational database. We respond to the need to deploy technologies sufficient to allow users to guide themselves to areas of local structure by casting the space of 'views' of an OLAP database as a combinatorial object of all projections and subsets, and 'view discovery' as an search process over that lattice. We equip the view lattice with statistical information theoretical measures sufficient to support a combinatorial optimization process. We outline 'hop-chaining' as a particular view discovery algorithm over this object, wherein users are guided across a permutation of the dimensions by searching for successive two-dimensional views, pushing seen dimensions into an increasingly large background filter in a 'spiraling' search process. We illustrate this work in the context of data cubes recording summary statistics for radiation portal monitors at US ports.

  10. View Discovery in OLAP Databases through Statistical Combinatorial Optimization

    SciTech Connect

    Joslyn, Cliff A.; Burke, Edward J.; Critchlow, Terence J.

    2009-05-01

    The capability of OLAP database software systems to handle data complexity comes at a high price for analysts, presenting them a combinatorially vast space of views of a relational database. We respond to the need to deploy technologies sufficient to allow users to guide themselves to areas of local structure by casting the space of ``views'' of an OLAP database as a combinatorial object of all projections and subsets, and ``view discovery'' as an search process over that lattice. We equip the view lattice with statistical information theoretical measures sufficient to support a combinatorial optimization process. We outline ``hop-chaining'' as a particular view discovery algorithm over this object, wherein users are guided across a permutation of the dimensions by searching for successive two-dimensional views, pushing seen dimensions into an increasingly large background filter in a ``spiraling'' search process. We illustrate this work in the context of data cubes recording summary statistics for radiation portal monitors at US ports.

  11. Incorporating Spatial Data into Enterprise Applications

    NASA Astrophysics Data System (ADS)

    Akiki, Pierre; Maalouf, Hoda

    The main goal of this chapter is to discuss the usage of spatial data within enterprise as well as smaller line-of-business applications. In particular, this chapter proposes new methodologies for storing and manipulating vague spatial data and provides methods for visualizing both crisp and vague spatial data. It also provides a comparison between different types of spatial data, mainly 2D crisp and vague spatial data, and their respective fields of application. Additionally, it compares existing commercial relational database management systems, which are the most widely used with enterprise applications, and discusses their deficiencies in terms of spatial data support. A new spatial extension package called Spatial Extensions (SPEX) is provided in this chapter and is tested on a software prototype.

  12. The M-OLAP Cube Selection Problem: A Hyper-polymorphic Algorithm Approach

    NASA Astrophysics Data System (ADS)

    Loureiro, Jorge; Belo, Orlando

    OLAP systems depend heavily on the materialization of multidimensional structures to speed-up queries, whose appropriate selection constitutes the cube selection problem. However, the recently proposed distribution of OLAP structures emerges to answer new globalization's requirements, capturing the known advantages of distributed databases. But this hardens the search for solutions, especially due to the inherent heterogeneity, imposing an extra characteristic of the algorithm that must be used: adaptability. Here the emerging concept known as hyper-heuristic can be a solution. In fact, having an algorithm where several (meta-)heuristics may be selected under the control of a heuristic has an intrinsic adaptive behavior. This paper presents a hyper-heuristic polymorphic algorithm used to solve the extended cube selection and allocation problem generated in M-OLAP architectures.

  13. Developing Access Control Model of Web OLAP over Trusted and Collaborative Data Warehouses

    NASA Astrophysics Data System (ADS)

    Fugkeaw, Somchart; Mitrpanont, Jarernsri L.; Manpanpanich, Piyawit; Juntapremjitt, Sekpon

    This paper proposes the design and development of Role- based Access Control (RBAC) model for the Single Sign-On (SSO) Web-OLAP query spanning over multiple data warehouses (DWs). The model is based on PKI Authentication and Privilege Management Infrastructure (PMI); it presents a binding model of RBAC authorization based on dimension privilege specified in attribute certificate (AC) and user identification. Particularly, the way of attribute mapping between DW user authentication and privilege of dimensional access is illustrated. In our approach, we apply the multi-agent system to automate flexible and effective management of user authentication, role delegation as well as system accountability. Finally, the paper culminates in the prototype system A-COLD (Access Control of web-OLAP over multiple DWs) that incorporates the OLAP features and authentication and authorization enforcement in the multi-user and multi-data warehouse environment.

  14. Multidimensional Analysis and Location Intelligence Application for Spatial Data Warehouse Hotspot in Indonesia using SpagoBI

    NASA Astrophysics Data System (ADS)

    Uswatun Hasanah, Gamma; Trisminingsih, Rina

    2016-01-01

    Spatial data warehouse refers to data warehouse which has a spatial component that represents the geographic location of the position or an object on the Earth's surface. Spatial data warehouse can be visualized in the form of a crosstab tables, graphs, and maps. Spatial data warehouse of hotspot in Indonesia has been constructed by researchers from FIRM NASA 2006-2015. This research develops multidimensional analysis module and location intelligence module using SpagoBI. The multidimensional analysis module is able to visualize online analytical processing (OLAP). The location intelligence module creates dynamic map visualization in map zone and map point. Map zone can display the different colors based on the number of hotspot in each region and map point can display different sizes of the point to represent the number of hotspots in each region. This research is expected to facilitate users in the presentation of hotspot data as needed.

  15. Spatial transformations: from fundamentals to applications

    PubMed Central

    Foster, Robert; Grant, Patrick; Hao, Yang; Hibbins, Alastair; Philbin, Thomas; Sambles, Roy

    2015-01-01

    This paper forms the introduction to this themed issue of Philosophical Transactions of the Royal Society A on ‘Spatial transformations’, arising from the Royal Society Scientific Discussion Meeting held in January 2015. The paper begins with a review of the concepts and history of spatial transformations, followed by a discussion of the contributions from the papers in this themed issue. A summary of the advantages and current limitations of spatial transformations concludes the paper, with the key challenges identified at the Scientific Discussion Meeting also given. PMID:26217061

  16. Hedonic approaches based on spatial econometrics and spatial statistics: application to evaluation of project benefits

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Morito; Seya, Hajime

    2009-12-01

    This study discusses the theoretical foundation of the application of spatial hedonic approaches—the hedonic approach employing spatial econometrics or/and spatial statistics—to benefits evaluation. The study highlights the limitations of the spatial econometrics approach since it uses a spatial weight matrix that is not employed by the spatial statistics approach. Further, the study presents empirical analyses by applying the Spatial Autoregressive Error Model (SAEM), which is based on the spatial econometrics approach, and the Spatial Process Model (SPM), which is based on the spatial statistics approach. SPMs are conducted based on both isotropy and anisotropy and applied to different mesh sizes. The empirical analysis reveals that the estimated benefits are quite different, especially between isotropic and anisotropic SPM and between isotropic SPM and SAEM; the estimated benefits are similar for SAEM and anisotropic SPM. The study demonstrates that the mesh size does not affect the estimated amount of benefits. Finally, the study provides a confidence interval for the estimated benefits and raises an issue with regard to benefit evaluation.

  17. APPLICATION OF SPATIAL INFORMATION TECHNOLOGY TO PETROLEUM RESOURCE ASSESSMENT ANALYSIS.

    USGS Publications Warehouse

    Miller, Betty M.; Domaratz, Michael A.

    1984-01-01

    Petroleum resource assessment procedures require the analysis of a large volume of spatial data. The US Geological Survey (USGS) has developed and applied spatial information handling procedures and digital cartographic techniques to a recent study involving the assessment of oil and gas resource potential for 74 million acres of designated and proposed wilderness lands in the western United States. The part of the study which dealt with the application of spatial information technology to petroleum resource assessment procedures is reviewed. A method was designed to expedite the gathering, integrating, managing, manipulating and plotting of spatial data from multiple data sources that are essential in modern resource assessment procedures.

  18. Radiographic applications of spatial frequency multiplexing

    NASA Technical Reports Server (NTRS)

    Macovski, A.

    1981-01-01

    The application of spacial frequency encoding techniques which allow different regions of the X-ray spectrum to be encoded on conventional radiographs was studied. Clinical considerations were reviewed, as were experimental studies involving the encoding and decoding of X-ray images at different energies and the subsequent processing of the data to produce images of specific materials in the body.

  19. Applications of spatially offset Raman spectroscopy to defense and security

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason; Hopkins, Rebecca

    2016-05-01

    Spatially offset Raman spectroscopy (SORS) allows for sub-surface and through barrier detection and has applications in drug analysis, cancer detection, forensic science, as well as defense and security. This paper reviews previous efforts in SORS and other through barrier Raman techniques and presents a discussion on current research in defense and security applications.

  20. Proposal of Interactive Applications to Enhance Student's Spatial Perception

    ERIC Educational Resources Information Center

    Moran, Samuel; Rubio, Ramon; Gallego, Ramon; Suarez, Javier; Martin, Santiago

    2008-01-01

    The aim of this series of applications is to enhance students' spatial perception capacity by means of exercises that require the student to concentrate on mentally recreating the figures represented. Each application is designed with an increasing level of difficulty, designed to increase the students' concentration and train their spatial…

  1. Spatial extended hazard model with application to prostate cancer survival.

    PubMed

    Li, Li; Hanson, Timothy; Zhang, Jiajia

    2015-06-01

    This article develops a Bayesian semiparametric approach to the extended hazard model, with generalization to high-dimensional spatially grouped data. County-level spatial correlation is accommodated marginally through the normal transformation model of Li and Lin (2006, Journal of the American Statistical Association 101, 591-603), using a correlation structure implied by an intrinsic conditionally autoregressive prior. Efficient Markov chain Monte Carlo algorithms are developed, especially applicable to fitting very large, highly censored areal survival data sets. Per-variable tests for proportional hazards, accelerated failure time, and accelerated hazards are efficiently carried out with and without spatial correlation through Bayes factors. The resulting reduced, interpretable spatial models can fit significantly better than a standard additive Cox model with spatial frailties. PMID:25521422

  2. Design and implementation of GGEarth spatial data service application system

    NASA Astrophysics Data System (ADS)

    Chen, Jianhua; Miao, Fang; Wang, Weihong; Wang, Huajun

    2009-06-01

    The digital earth concept has aroused strong repercussions and been arousing researches boom both at home and abroad once it is proposed. Many digital earth prototype systems have been researched and distributed in worldwide, and the Google Earth is more typical. The booming development of digital earth's research and its prototype's development bring about G/S mode timely, a novel spatial information distributing access, and organization software architecture mode. Based on native GML spatial database system and Google Earth, with G/S mode as its architecture, and combination with GML/KML compressive transport and transformation, this paper proposed and designed the software architecture of GGEarth spatial data service application system, the research content and key implementation technologies were given. This system provides functions of data presentation, query, update and spatial analysis, which uses native GML spatial database (and GML, KML documents) as the standard data center, and the client based on Google Earth COM API as the front-end. This system can be applied in fields of digital city, digital tourism and traditional Web GIS. The authors developed the GGEarth experimental system and ran it with the data of '5.12' Wenchuan earthquake timing and the model data of digital Jiuzhaigou virtual tourism. Some running screenshots are also given.

  3. Management model application at nested spatial levels in Mediterranean Basins

    NASA Astrophysics Data System (ADS)

    Lo Porto, Antonio; De Girolamo, Anna Maria; Froebrich, Jochen

    2014-05-01

    In the EU Water Framework Directive (WFD) implementation processes, hydrological and water quality models can be powerful tools that allow to design and test alternative management strategies, as well as judging their general feasibility and acceptance. Although in recent decades several models have been developed, their use in Mediterranean basins, where rivers have a temporary character, is quite complex and there is limited information in literature which can facilitate model applications and result evaluations in this region. The high spatial variability which characterizes rainfall events, soil hydrological properties and land uses of Mediterranean basin makes more difficult to simulate hydrological and water quality in this region than in other Countries. This variability also has several implications in modeling simulations results especially when simulations at different spatial scale are needed for watershed management purpose. It is well known that environmental processes operating at different spatial scale determine diverse impacts on water quality status (hydrological, chemical, ecological). Hence, the development of management strategies have to include both large scale (watershed) and local spatial scales approaches (e.g. stream reach). This paper presents the results of a study which analyzes how the spatial scale affects the results of hydrologic process and water quality of model simulations in a Mediterranean watershed. Several aspects involved in modeling hydrological and water quality processes at different spatial scale for river basin management are investigated including model data requirements, data availability, model results and uncertainty. A hydrologic and water quality model (SWAT) was used to simulate hydrologic processes and water quality at different spatial scales in the Candelaro river basin (Puglia, S-E Italy) and to design management strategies to reach as possible WFD goals. When studying a basin to assess its current status

  4. Spatial effects in real networks: Measures, null models, and applications

    NASA Astrophysics Data System (ADS)

    Ruzzenenti, Franco; Picciolo, Francesco; Basosi, Riccardo; Garlaschelli, Diego

    2012-12-01

    Spatially embedded networks are shaped by a combination of purely topological (space-independent) and space-dependent formation rules. While it is quite easy to artificially generate networks where the relative importance of these two factors can be varied arbitrarily, it is much more difficult to disentangle these two architectural effects in real networks. Here we propose a solution to this problem, by introducing global and local measures of spatial effects that, through a comparison with adequate null models, effectively filter out the spurious contribution of nonspatial constraints. Our filtering allows us to consistently compare different embedded networks or different historical snapshots of the same network. As a challenging application we analyze the World Trade Web, whose topology is known to depend on geographic distances but is also strongly determined by nonspatial constraints (degree sequence or gross domestic product). Remarkably, we are able to detect weak but significant spatial effects both locally and globally in the network, showing that our method succeeds in retrieving spatial information even when nonspatial factors dominate. We finally relate our results to the economic literature on gravity models and trade globalization.

  5. Large capacity spatially multiplexed optical memories for incoherent correlator application

    NASA Astrophysics Data System (ADS)

    Yu, Francis T.

    1987-05-01

    We have, in this research program, completed various significant aspects on the study of a Large Capacity Spatially Multiplexed Optical Correlator. They are summarized in the following paragraphs: We have quantitatively analyzed the noise performance of an incoherent optical signal processor. The effects due to temporal coherence and due to spatial coherence were studied. In this period, we have also completed research on a real-time large-capacity rapid-scanning optical correlator utilizing a rotating grating concept. We have shown that the proposed optical scanning correlator is capable of processing large-capacity optical memories with rapid spectrum scanning. With the implementation of a closed-circuit TV system the OSC system can be applied in real-world situations. A study of polychromatic correlation by spectral-spatial matched filtering has been conducted. Application of this technique to large capability spatially multiplexing matched filter synthesis is discussed. This technique offers true color signal detection, which is suitable for color image recognition and identification. We have also developed a joint transform correlation concept. This technique utilizes a magneto-optic device with a liquid crystal light valve.

  6. [Scan statistic theory and its application in spatial epidemiology].

    PubMed

    Li, Xiu-yang; Chen, Kun

    2008-08-01

    To introduce the basic concept of scan statistic, its computation method and application in the area of spatial epidemiology. Retrospective space-time permutation statistics for evaluating the clustering of disease monitoring program is illustrated, using data on recent acute onset of cardiovascular disease in Hangzhou, China. Calculations were performed with SaTScan Version 7.0.3. With 999 Monte Carlo replications, the program took 5 seconds to run on a 100-MHz Pentium PC. The geographical surveillance program on acute onset clusters of cardiovascular disease, data which showed statistical significance, would include: a) from January 1, 1997 to February 28, 2007 in Qiantan township, Jiande county (P = 0.001); b) highly significant between January 1, 1997 and February 28, 1999 for Lushan street, Lingqiao township in Fuyang county (P = 0.003); c) between March 1, 2001 and February 29, 2004 for Dayuan town, Xinyi town, Shouxiang town in Fuyang (P = 0.004); d) between March 1, 2004 and Feb 28, 2006 for Chengzhan street, Ziyang street, Hubin street, Qinbo street, Xiaoying street, Wangjiang street, Chaoming street, Changqing street, Wulin street, Tianshui street, Wenhui street and Shiqiao street in Hangzhou (P = 0.005), respectively. The retrospective space-time permutation statistics seems useful as a screening tool for identifying the cluster of disease. Scan statistics are practical and effective method for deciding which cluster alarms would merit further investigation and which clusters are probably chance occurrences in the study of spatial epidemiology. PMID:19103124

  7. A spatial haplotype copying model with applications to genotype imputation.

    PubMed

    Yang, Wen-Yun; Hormozdiari, Farhad; Eskin, Eleazar; Pasaniuc, Bogdan

    2015-05-01

    Ever since its introduction, the haplotype copy model has proven to be one of the most successful approaches for modeling genetic variation in human populations, with applications ranging from ancestry inference to genotype phasing and imputation. Motivated by coalescent theory, this approach assumes that any chromosome (haplotype) can be modeled as a mosaic of segments copied from a set of chromosomes sampled from the same population. At the core of the model is the assumption that any chromosome from the sample is equally likely to contribute a priori to the copying process. Motivated by recent works that model genetic variation in a geographic continuum, we propose a new spatial-aware haplotype copy model that jointly models geography and the haplotype copying process. We extend hidden Markov models of haplotype diversity such that at any given location, haplotypes that are closest in the genetic-geographic continuum map are a priori more likely to contribute to the copying process than distant ones. Through simulations starting from the 1000 Genomes data, we show that our model achieves superior accuracy in genotype imputation over the standard spatial-unaware haplotype copy model. In addition, we show the utility of our model in selecting a small personalized reference panel for imputation that leads to both improved accuracy as well as to a lower computational runtime than the standard approach. Finally, we show our proposed model can be used to localize individuals on the genetic-geographical map on the basis of their genotype data. PMID:25526526

  8. Spatial and statistical GIS Applications for geological and environmental courses

    NASA Astrophysics Data System (ADS)

    Marsellos, A.; Tsakiri, K.

    2012-12-01

    Building student's career through undergraduate and graduate courses integrated with modern statistical and GIS software foster a competitive curriculum for their future employment. We present examples that may be introduced in geological courses (e.g. mineralogy, geomorphology, geochronology, structural geology, tectonics, stratigraphy) and environmental courses (natural hazards, hydrology, atmospheric science). Univariate and multivariate statistical models can be used for the interpretation and mapping of the geological and environmental problems. Some of the main statistical univariate models such as the normal distribution as well as the multivariate methods such as the principal component analysis, cluster analysis and factor analysis are the basic methods for understanding the variables of the environmental and geological problems. Examples are presented describing the basic steps for the solution of the problems. Some of the geological problems in different scales are the interpretation of 3D structural data, identification of suitable outcrops for mapping shear sense kinematic indicators. categorical or cluster analysis on lineations depending on their origin, topology of mineral assemblages and spatial distribution of their c-axis, distinguishing paleo-elevations using cluster analysis in geomorphological structures using LiDAR intensity and elevation data for determination of meander evolution patterns and prediction of vulnerable sites for flooding or landsliding. Other applications in atmospheric and hydrology science are the prediction of ground level ozone and the decomposition of water use time series. Those fundamental statistical and spatial concepts may be used in the field or in the lab. In the lab, modern computers and friendly interface user software allow students to process data using advanced statistical methods and GIS techniques. Modern applications in tablets or smart phones may complement field work. Teaching those methods can

  9. Spatial processing techniques for satellite altimetry applications in continental hydrology

    NASA Astrophysics Data System (ADS)

    Maillard, Philippe; Calmant, Stéphane

    2013-10-01

    Radar-based satellite altimetry is a well recognized measuring technique with good precision for oceanographic applications. For continental hydrology, its use is complicated by a number of factors such as river width, satellite crossing angle and noise from the river banks or islands. These factors make precision vary significantly. The satellite crossing points can be made into virtual gauging stations that can complement the existing network of in situ stations. This article describes a series of spatially explicit processing to correct or exclude altimetry measurements not related to the water level. While some processing take advantage of a priori information such as the centerline of the river, other processing are based on pattern recognition to characterize the shape described by the sequence of points. These problems are dealt with by fitting a second degree polynomial curve to the sequence of points and characterizing its shape. The correction is applied by determining a weight for each point in the crossing sequence of measurements. These processing approaches have been combined into a single tool called VHSTOOL. The method is tested on a 1000 km stretch of the S˜ao Francisco River in Brazil. Data from Envisat cover the 2003-2010 period while the recently launched Altika sensor provided data for a few months in 2013. Results show that the average accuracy of 60 cm obtained (45 cm by removing outliers) is comparable to that of completely manual methods. Altika measurements could not be validated since no recent in situ data was available but initial evaluation suggests increased details should bring some improvements over Envisat data.

  10. Correlation of Spatially Filtered Dynamic Speckles in Distance Measurement Application

    SciTech Connect

    Semenov, Dmitry V.; Nippolainen, Ervin; Kamshilin, Alexei A.; Miridonov, Serguei V.

    2008-04-15

    In this paper statistical properties of spatially filtered dynamic speckles are considered. This phenomenon was not sufficiently studied yet while spatial filtering is an important instrument for speckles velocity measurements. In case of spatial filtering speckle velocity information is derived from the modulation frequency of filtered light power which is measured by photodetector. Typical photodetector output is represented by a narrow-band random noise signal which includes non-informative intervals. Therefore more or less precious frequency measurement requires averaging. In its turn averaging implies uncorrelated samples. However, conducting research we found that correlation is typical property not only of dynamic speckle patterns but also of spatially filtered speckles. Using spatial filtering the correlation is observed as a response of measurements provided to the same part of the object surface or in case of simultaneously using several adjacent photodetectors. Found correlations can not be explained using just properties of unfiltered dynamic speckles. As we demonstrate the subject of this paper is important not only from pure theoretical point but also from the point of applied speckle metrology. E.g. using single spatial filter and an array of photodetector can greatly improve accuracy of speckle velocity measurements.

  11. Bayesian spatial transformation models with applications in neuroimaging data

    PubMed Central

    Miranda, Michelle F.; Zhu, Hongtu; Ibrahim, Joseph G.

    2013-01-01

    Summary The aim of this paper is to develop a class of spatial transformation models (STM) to spatially model the varying association between imaging measures in a three-dimensional (3D) volume (or 2D surface) and a set of covariates. Our STMs include a varying Box-Cox transformation model for dealing with the issue of non-Gaussian distributed imaging data and a Gaussian Markov Random Field model for incorporating spatial smoothness of the imaging data. Posterior computation proceeds via an efficient Markov chain Monte Carlo algorithm. Simulations and real data analysis demonstrate that the STM significantly outperforms the voxel-wise linear model with Gaussian noise in recovering meaningful geometric patterns. Our STM is able to reveal important brain regions with morphological changes in children with attention deficit hyperactivity disorder. PMID:24128143

  12. Spatial filtering efficiency of monostatic biaxial lidar: analysis and applications.

    PubMed

    Agishev, Ravil R; Comeron, Adolfo

    2002-12-20

    Results of lidar modeling based on spatial-angular filtering efficiency criteria are presented. Their analysis shows that the low spatial-angular filtering efficiency of traditional visible and near-infrared systems is an important cause of low signal/background-radiation ratio (SBR) at the photodetector input The low SBR may be responsible for considerable measurement errors and ensuing the low accuracy of the retrieval of atmospheric optical parameters. As shown, the most effective protection against sky background radiation for groundbased biaxial lidars is the modifying of their angular field according to a spatial-angular filtering efficiency criterion. Some effective approaches to achieve a high filtering efficiency for the receiving system optimization are discussed. PMID:12510915

  13. GIS application on spatial landslide analysis using statistical based models

    NASA Astrophysics Data System (ADS)

    Pradhan, Biswajeet; Lee, Saro; Buchroithner, Manfred F.

    2009-09-01

    This paper presents the assessment results of spatially based probabilistic three models using Geoinformation Techniques (GIT) for landslide susceptibility analysis at Penang Island in Malaysia. Landslide locations within the study areas were identified by interpreting aerial photographs, satellite images and supported with field surveys. Maps of the topography, soil type, lineaments and land cover were constructed from the spatial data sets. There are ten landslide related factors were extracted from the spatial database and the frequency ratio, fuzzy logic, and bivariate logistic regression coefficients of each factor was computed. Finally, landslide susceptibility maps were drawn for study area using frequency ratios, fuzzy logic and bivariate logistic regression models. For verification, the results of the analyses were compared with actual landslide locations in study area. The verification results show that bivariate logistic regression model provides slightly higher prediction accuracy than the frequency ratio and fuzzy logic models.

  14. Full Spatial Resolution Infrared Sounding Application in the Preconvection Environment

    NASA Astrophysics Data System (ADS)

    Liu, C.; Liu, G.; Lin, T.

    2013-12-01

    Advanced infrared (IR) sounders such as the Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI) provide atmospheric temperature and moisture profiles with high vertical resolution and high accuracy in preconvection environments. The derived atmospheric stability indices such as convective available potential energy (CAPE) and lifted index (LI) from advanced IR soundings can provide critical information 1 ; 6 h before the development of severe convective storms. Three convective storms are selected for the evaluation of applying AIRS full spatial resolution soundings and the derived products on providing warning information in the preconvection environments. In the first case, the AIRS full spatial resolution soundings revealed local extremely high atmospheric instability 3 h ahead of the convection on the leading edge of a frontal system, while the second case demonstrates that the extremely high atmospheric instability is associated with the local development of severe thunderstorm in the following hours. The third case is a local severe storm that occurred on 7-8 August 2010 in Zhou Qu, China, which caused more than 1400 deaths and left another 300 or more people missing. The AIRS full spatial resolution LI product shows the atmospheric instability 3.5 h before the storm genesis. The CAPE and LI from AIRS full spatial resolution and operational AIRS/AMSU soundings along with Geostationary Operational Environmental Satellite (GOES) Sounder derived product image (DPI) products were analyzed and compared. Case studies show that full spatial resolution AIRS retrievals provide more useful warning information in the preconvection environments for determining favorable locations for convective initiation (CI) than do the coarser spatial resolution operational soundings and lower spectral resolution GOES Sounder retrievals. The retrieved soundings are also tested in a regional data assimilation WRF 3D-var system to evaluate the

  15. Bayesian spatial models: Applications for tropospheric ozone data

    NASA Astrophysics Data System (ADS)

    Menezes, Kim Anne

    1999-12-01

    This research addresses issues pertaining to trend estimation in tropospheric ozone data as well as estimation of the spatial correlation structure of these data collected at multiple monitoring sites. Assessing long-term trends in tropospheric ozone data is imperative because of its adverse effect on human health and on agricultural crops. Moreover, we also estimate the spatial correlation structure of such data, which is essential for spatial trend estimation, spatial prediction and for redesigning an existing network of stations. The U.S. Environmental Protection Agency's (EPA) National Ambient Air Quality Standard for ozone is stated in terms of exceedances of a specified threshold level. Therefore, the EPA is concerned with the long-term trend in the probability of an exceedance. In the first part of my dissertation we build a multivariate nonparametric probit regression model estimated within a hierarchical Bayes framework to model the probability of an exceedance after allowing for the effects of changing meteorological conditions. There are three advantages to using this model. First, the trends estimated at each site in a region can be separated into a city-wide component that is common to all sites, and a site-specific component that is unique to the individual site. Second, the hierarchical Bayes framework allows for the ``borrowing of strength'' from data collected at other monitoring sites to increase the information available regarding the trend at each individual site. Third, the nonparametric model does not require the a priori specification of the functional forms relating the probability of an exceedance to the meteorological variables. Ozone data from four Houston monitoring sites for the period 1981-1997 are analyzed. In the second part we provide a penalized likelihood approach to estimating the spatial correlation structure when the assumptions of stationarity and isotropy are violated. The spatial correlation structure under these

  16. Implementing an SIG based platform of application and service for city spatial information in Shanghai

    NASA Astrophysics Data System (ADS)

    Yu, Bailang; Wu, Jianping

    2006-10-01

    Spatial Information Grid (SIG) is an infrastructure that has the ability to provide the services for spatial information according to users' needs by means of collecting, sharing, organizing and processing the massive distributed spatial information resources. This paper presents the architecture, technologies and implementation of the Shanghai City Spatial Information Application and Service System, a SIG based platform, which is an integrated platform that serves for administration, planning, construction and development of the city. In the System, there are ten categories of spatial information resources, including city planning, land-use, real estate, river system, transportation, municipal facility construction, environment protection, sanitation, urban afforestation and basic geographic information data. In addition, spatial information processing services are offered as a means of GIS Web Services. The resources and services are all distributed in different web-based nodes. A single database is created to store the metadata of all the spatial information. A portal site is published as the main user interface of the System. There are three main functions in the portal site. First, users can search the metadata and consequently acquire the distributed data by using the searching results. Second, some spatial processing web applications that developed with GIS Web Services, such as file format conversion, spatial coordinate transfer, cartographic generalization and spatial analysis etc, are offered to use. Third, GIS Web Services currently available in the System can be searched and new ones can be registered. The System has been working efficiently in Shanghai Government Network since 2005.

  17. Spatial noise in microdisplays for near-to-eye applications

    NASA Astrophysics Data System (ADS)

    Hastings, Arthur R., Jr.; Draper, Russell S.; Wood, Michael V.; Fellowes, David A.

    2011-06-01

    Spatial noise in imaging systems has been characterized and its impact on image quality metrics has been addressed primarily with respect to the introduction of this noise at the sensor component. However, sensor fixed pattern noise is not the only source of fixed pattern noise in an imaging system. Display fixed pattern noise cannot be easily mitigated in processing and, therefore, must be addressed. In this paper, a thorough examination of the amount and the effect of display fixed pattern noise is presented. The specific manifestation of display fixed pattern noise is dependent upon the display technology. Utilizing a calibrated camera, US Army RDECOM CERDEC NVESD has developed a microdisplay (μdisplay) spatial noise data collection capability. Noise and signal power spectra were used to characterize the display signal to noise ratio (SNR) as a function of spatial frequency analogous to the minimum resolvable temperature difference (MRTD) of a thermal sensor. The goal of this study is to establish a measurement technique to characterize μdisplay limiting performance to assist in proper imaging system specification.

  18. Learning from Heterogeneous Data Sources: An Application in Spatial Proteomics

    PubMed Central

    Breckels, Lisa M.; Holden, Sean B.; Wojnar, David; Mulvey, Claire M.; Christoforou, Andy; Groen, Arnoud; Trotter, Matthew W. B.; Kohlbacher, Oliver; Lilley, Kathryn S.; Gatto, Laurent

    2016-01-01

    Sub-cellular localisation of proteins is an essential post-translational regulatory mechanism that can be assayed using high-throughput mass spectrometry (MS). These MS-based spatial proteomics experiments enable us to pinpoint the sub-cellular distribution of thousands of proteins in a specific system under controlled conditions. Recent advances in high-throughput MS methods have yielded a plethora of experimental spatial proteomics data for the cell biology community. Yet, there are many third-party data sources, such as immunofluorescence microscopy or protein annotations and sequences, which represent a rich and vast source of complementary information. We present a unique transfer learning classification framework that utilises a nearest-neighbour or support vector machine system, to integrate heterogeneous data sources to considerably improve on the quantity and quality of sub-cellular protein assignment. We demonstrate the utility of our algorithms through evaluation of five experimental datasets, from four different species in conjunction with four different auxiliary data sources to classify proteins to tens of sub-cellular compartments with high generalisation accuracy. We further apply the method to an experiment on pluripotent mouse embryonic stem cells to classify a set of previously unknown proteins, and validate our findings against a recent high resolution map of the mouse stem cell proteome. The methodology is distributed as part of the open-source Bioconductor pRoloc suite for spatial proteomics data analysis. PMID:27175778

  19. Learning from Heterogeneous Data Sources: An Application in Spatial Proteomics.

    PubMed

    Breckels, Lisa M; Holden, Sean B; Wojnar, David; Mulvey, Claire M; Christoforou, Andy; Groen, Arnoud; Trotter, Matthew W B; Kohlbacher, Oliver; Lilley, Kathryn S; Gatto, Laurent

    2016-05-01

    Sub-cellular localisation of proteins is an essential post-translational regulatory mechanism that can be assayed using high-throughput mass spectrometry (MS). These MS-based spatial proteomics experiments enable us to pinpoint the sub-cellular distribution of thousands of proteins in a specific system under controlled conditions. Recent advances in high-throughput MS methods have yielded a plethora of experimental spatial proteomics data for the cell biology community. Yet, there are many third-party data sources, such as immunofluorescence microscopy or protein annotations and sequences, which represent a rich and vast source of complementary information. We present a unique transfer learning classification framework that utilises a nearest-neighbour or support vector machine system, to integrate heterogeneous data sources to considerably improve on the quantity and quality of sub-cellular protein assignment. We demonstrate the utility of our algorithms through evaluation of five experimental datasets, from four different species in conjunction with four different auxiliary data sources to classify proteins to tens of sub-cellular compartments with high generalisation accuracy. We further apply the method to an experiment on pluripotent mouse embryonic stem cells to classify a set of previously unknown proteins, and validate our findings against a recent high resolution map of the mouse stem cell proteome. The methodology is distributed as part of the open-source Bioconductor pRoloc suite for spatial proteomics data analysis. PMID:27175778

  20. Nonparametric Spatial Models for Extremes: Application to Extreme Temperature Data.

    PubMed

    Fuentes, Montserrat; Henry, John; Reich, Brian

    2013-03-01

    Estimating the probability of extreme temperature events is difficult because of limited records across time and the need to extrapolate the distributions of these events, as opposed to just the mean, to locations where observations are not available. Another related issue is the need to characterize the uncertainty in the estimated probability of extreme events at different locations. Although the tools for statistical modeling of univariate extremes are well-developed, extending these tools to model spatial extreme data is an active area of research. In this paper, in order to make inference about spatial extreme events, we introduce a new nonparametric model for extremes. We present a Dirichlet-based copula model that is a flexible alternative to parametric copula models such as the normal and t-copula. The proposed modelling approach is fitted using a Bayesian framework that allow us to take into account different sources of uncertainty in the data and models. We apply our methods to annual maximum temperature values in the east-south-central United States. PMID:24058280

  1. SOIL PHOSPHOROUS SPATIAL DISTRIBUTION IN PASTURES RECEIVING POULTRY LITTER APPLICATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Environmentally-based P management strategies could be improved by delineating management zones incorporating the effects of landscape position on soil morphology, hydrology, and soil P distribution. Three farm pasture sites in SW Missouri receiving long-term poultry litter applications were sampled...

  2. In vivo Application of Short-lag Spatial Coherence and Harmonic Spatial Coherence Imaging in Fetal Ultrasound

    PubMed Central

    Kakkad, Vaibhav; Dahl, Jeremy; Ellestad, Sarah; Trahey, Gregg

    2014-01-01

    Fetal scanning is one of the most common applications of ultrasound imaging and serves as a source of vital information about maternal and fetal health. Visualization of clinically relevant structures, however, can be severely compromised in difficult-to-image patients due to poor resolution and the presence of high levels of acoustical noise or clutter. We have developed novel coherence-based beamforming methods called Short-Lag Spatial Coherence (SLSC) imaging and Harmonic Spatial Coherence imaging (HSCI) and applied them to suppress the effects of clutter in fetal imaging. This method is used to create images of the spatial coherence of the backscattered ultrasound as opposed to images of echo magnitude. We present the results of a patient study to assess the benefits of coherence-based beamforming in the context of first trimester fetal exams. Matched fundamental B-mode, SLSC, harmonic B-mode and HSCI images were generated using raw RF data collected on 11 volunteers in the first trimester of pregnancy. The images were compared for qualitative differences in image texture and target conspicuity as well as using quantitative imaging metrics such as SNR, CNR and contrast. SLSC and HSCI showed statistically significant improvements across all imaging metrics compared to B-mode and harmonic B-mode respectively. These improvements were greatest for poor quality B-mode images where contrast of anechoic targets was improved from 15 dB in fundamental B-mode to 27 dB in SLSC and 17 dB in harmonic B-mode to 30 dB in HSCI. CNR improved from 1.4 to 2.5 in the fundamental images and 1.4 to 3.1 in the harmonic case. These results exhibit the potential of coherence-based beamforming to improve image quality and target detectability, especially in high noise environments. PMID:25116292

  3. Application of geo-spatial technology in schistosomiasis modelling in Africa: a review.

    PubMed

    Manyangadze, Tawanda; Chimbari, Moses John; Gebreslasie, Michael; Mukaratirwa, Samson

    2015-01-01

    Schistosomiasis continues to impact socio-economic development negatively in sub-Saharan Africa. The advent of spatial technologies, including geographic information systems (GIS), Earth observation (EO) and global positioning systems (GPS) assist modelling efforts. However, there is increasing concern regarding the accuracy and precision of the current spatial models. This paper reviews the literature regarding the progress and challenges in the development and utilization of spatial technology with special reference to predictive models for schistosomiasis in Africa. Peer-reviewed papers identified through a PubMed search using the following keywords: geo-spatial analysis OR remote sensing OR modelling OR earth observation OR geographic information systems OR prediction OR mapping AND schistosomiasis AND Africa were used. Statistical uncertainty, low spatial and temporal resolution satellite data and poor validation were identified as some of the factors that compromise the precision and accuracy of the existing predictive models. The need for high spatial resolution of remote sensing data in conjunction with ancillary data viz. ground-measured climatic and environmental information, local presence/absence intermediate host snail surveys as well as prevalence and intensity of human infection for model calibration and validation are discussed. The importance of a multidisciplinary approach in developing robust, spatial data capturing, modelling techniques and products applicable in epidemiology is highlighted. PMID:26618307

  4. Parallelized genetic optimization of spatial light modulator addressing for diffractive applications.

    PubMed

    Haist, Tobias; Lingel, Christian; Adler, Rodolfo; Osten, Wolfgang

    2014-03-01

    We describe a new technique for optimizing the addressing of spatial light modulators in dynamic holographic applications. The method utilizes 200 times parallelization using imaging of subholograms in combination with genetic optimization. Compared to a fixed linear addressing curve for all different gratings, the diffraction efficiency can be improved by up to 25% for a Holoeye Pluto LCoS modulator. PMID:24663371

  5. Phase conjugation of mode scrambled optical beams Application to spatial recovery and interbeam temporal information exchange

    NASA Astrophysics Data System (ADS)

    Yahalom, Ram; Kyuma, Kazuo; Yariv, Amnon

    1987-03-01

    Coupling of temporal information between two beams is demonstrated using a combination of a multimode fiber and a photorefractive passive phase conjugation mirror. It is shown that the polarization and spatial properties are fully recovered but temporal information is exchanged. The theoretical explanation for these phenomena and possible applications are discussed.

  6. Progressive phase conjugation and its application in reconfigurable spatial-mode extraction and conversion

    NASA Astrophysics Data System (ADS)

    Okamoto, Atsushi; Maeda, Tomohiro; Hirasaki, Yuki; Tomita, Akihisa; Sato, Kunihiro

    2014-05-01

    We develop a new technology, which is referred to as progressive phase conjugation (PPC), in which phase conjugation is electrically performed without requiring a coherent reference beam by fusion using a reference-free spatial phase detection and spatial phase modulation. This method enables remote setting of a phase detector from the signal transmitter without an additional transmission line for the reference beam. It also enables realization of high-speed and dynamic wavefront compensation owing to its open-loop architecture using the single-shot phase detection method. Therefore, the PPC is applicable to a wide range of optical communication technologies, including the reconfigurable spatial-mode extraction and conversion of mode transmission in a multi-mode fiber (MMF). In our experiment, spatial modes are generated by directing a laser beam into a MMF with a 50-micron core diameter. At the output side of the optical fiber, the phase distributions of the spatial modes are detected using the reference-free phase detector constructed by combining a spatial filtering method with holographic diversity interferometry using two CCD imagers. Then, the phase conjugate distribution of the detected phase pattern is displayed on a LCOS-type SLM. We confirm that the PPC system can extract a specific mode pattern with a considerably low crosstalk of less than 1% by displaying the corresponding phase-conjugation pattern on the SLM. In addition, we demonstrated a reconfigurable spatial-mode conversion by the phase control technology using the SLM. By applying the spatial phase modulation to an optical beam incident on the SLM, the spatial mode of the output beam is flexibly changed.

  7. Assessing the quality of open spatial data for mobile location-based services research and applications

    NASA Astrophysics Data System (ADS)

    Ciepłuch, C.; Mooney, P.; Jacob, R.; Zheng, J.; Winstanely, A. C.

    2011-12-01

    New trends in GIS such as Volunteered Geographical Information (VGI), Citizen Science, and Urban Sensing, have changed the shape of the geoinformatics landscape. The OpenStreetMap (OSM) project provided us with an exciting, evolving, free and open solution as a base dataset for our geoserver and spatial data provider for our research. OSM is probably the best known and best supported example of VGI and user generated spatial content on the Internet. In this paper we will describe current results from the development of quality indicators for measures for OSM data. Initially we have analysed the Ireland OSM data in grid cells (5km) to gather statistical data about the completeness, accuracy, and fitness for purpose of the underlying spatial data. This analysis included: density of user contributions, spatial density of points and polygons, types of tags and metadata used, dominant contributors in a particular area or for a particular geographic feature type, etc. There greatest OSM activity and spatial data density is highly correlated with centres of large population. The ability to quantify and assess if VGI, such as OSM, is of sufficient quality for mobile mapping applications and Location-based services is critical to the future success of VGI as a spatial data source for these technologies.

  8. Hybrid modeling of spatial continuity for application to numerical inverse problems

    USGS Publications Warehouse

    Friedel, Michael J.; Iwashita, Fabio

    2013-01-01

    A novel two-step modeling approach is presented to obtain optimal starting values and geostatistical constraints for numerical inverse problems otherwise characterized by spatially-limited field data. First, a type of unsupervised neural network, called the self-organizing map (SOM), is trained to recognize nonlinear relations among environmental variables (covariates) occurring at various scales. The values of these variables are then estimated at random locations across the model domain by iterative minimization of SOM topographic error vectors. Cross-validation is used to ensure unbiasedness and compute prediction uncertainty for select subsets of the data. Second, analytical functions are fit to experimental variograms derived from original plus resampled SOM estimates producing model variograms. Sequential Gaussian simulation is used to evaluate spatial uncertainty associated with the analytical functions and probable range for constraining variables. The hybrid modeling of spatial continuity is demonstrated using spatially-limited hydrologic measurements at different scales in Brazil: (1) physical soil properties (sand, silt, clay, hydraulic conductivity) in the 42 km2 Vargem de Caldas basin; (2) well yield and electrical conductivity of groundwater in the 132 km2 fractured crystalline aquifer; and (3) specific capacity, hydraulic head, and major ions in a 100,000 km2 transboundary fractured-basalt aquifer. These results illustrate the benefits of exploiting nonlinear relations among sparse and disparate data sets for modeling spatial continuity, but the actual application of these spatial data to improve numerical inverse modeling requires testing.

  9. Design of data warehouse in teaching state based on OLAP and data mining

    NASA Astrophysics Data System (ADS)

    Zhou, Lijuan; Wu, Minhua; Li, Shuang

    2009-04-01

    The data warehouse and the data mining technology is one of information technology research hot topics. At present the data warehouse and the data mining technology in aspects and so on commercial, financial industry as well as enterprise's production, market marketing obtained the widespread application, but is relatively less in educational fields' application. Over the years, the teaching and management have been accumulating large amounts of data in colleges and universities, while the data can not be effectively used, in the light of social needs of the university development and the current status of data management, the establishment of data warehouse in university state, the better use of existing data, and on the basis dealing with a higher level of disposal --data mining are particularly important. In this paper, starting from the decision-making needs design data warehouse structure of university teaching state, and then through the design structure and data extraction, loading, conversion create a data warehouse model, finally make use of association rule mining algorithm for data mining, to get effective results applied in practice. Based on the data analysis and mining, get a lot of valuable information, which can be used to guide teaching management, thereby improving the quality of teaching and promoting teaching devotion in universities and enhancing teaching infrastructure. At the same time it can provide detailed, multi-dimensional information for universities assessment and higher education research.

  10. Research on spatial coding compressive spectral imaging and its applicability for rural survey

    NASA Astrophysics Data System (ADS)

    Chen, Yuheng; Ji, Yiqun; Zhou, Jiankang; Chen, Xinhua; Shen, Weimin

    Compressive spectral imaging combines traditional spectral imaging method with new concept of compressive sensing thus has the advantages such as reducing acquisition data amount, realizing snapshot imaging for large field of view and increasing image signal-to-noise and its preliminary application effectiveness has been explored by early usage on the occasions such as high-speed imaging and fluorescent imaging. In this paper, the application potentiality for spatial coding compressive spectral imaging technique on rural survey is revealed. The physical model for spatial coding compressive spectral imaging is built on which its data flow procession is analyzed and its data reconstruction issue is concluded. The existing sparse reconstruction methods are reviewed thus specific module based on the two-step iterative shrinkage/thresholding algorithm is built so as to execute the imaging data reconstruction. The simulating imaging experiment based on AVIRIS visible band data of a specific selected rural scene is carried out. The spatial identification and spectral featuring extraction capacity for different ground species are evaluated by visual judgment of both single band image and spectral curve. The data fidelity evaluation parameters (RMSE and PSNR) are put forward so as to verify the data fidelity maintaining ability of this compressive imaging method quantitatively. The application potentiality of spatial coding compressive spectral imaging on rural survey, crop monitoring, vegetation inspection and further agricultural development demand is verified in this paper.

  11. [Application of spatial relative risk estimation in communicable disease risk evaluation].

    PubMed

    Zhang, Yewu; Guo, Qing; Wang, Xiaofeng; Yu, Meng; Su, Xuemei; Dong, Yan; Zhang, Chunxi

    2015-05-01

    This paper summaries the application of adaptive kernel density algorithm in the spatial relative risk estimation of communicable diseases by using the reported data of infectious diarrhea (other than cholera, dysentery, typhoid and paratyphoid) in Ludian county and surrounding area in Yunnan province in 2013. Statistically significant fluctuations in an estimated risk function were identified through the use of asymptotic tolerance contours, and finally these data were visualized though disease mapping. The results of spatial relative risk estimation and disease mapping showed that high risk areas were in southeastern Shaoyang next to Ludian. Therefore, the spatial relative risk estimation of disease by using adaptive kernel density algorithm and disease mapping technique is a powerful method in identifying high risk population and areas. PMID:26080648

  12. Existence and continuity of bi-spatial random attractors and application to stochastic semilinear Laplacian equations

    NASA Astrophysics Data System (ADS)

    Li, Yangrong; Gu, Anhui; Li, Jia

    2015-01-01

    A concept of a bi-spatial random attractor for a random dynamical system is introduced. A unified result about existence and upper semi-continuity for a family of bi-spatial random attractors is obtained if a family of random systems is convergent, uniformly absorbing in an initial space and uniformly omega-compact in both initial and terminate spaces. The upper semi-continuity result improves all existing results even for single-spatial attractors. As an application of the abstract result, it is shown that every semilinear Laplacian equation on the entire space perturbed by a multiplicative and stochastic noise possesses an (L2, Lq)-random attractor with q > 2. Moreover, it is proved that the family of obtained attractors is upper semi-continuous at any density of noises and the family of attractors for the corresponding compact systems is both upper and lower semi-continuous at infinity under the topology of both spaces.

  13. Simulation of spatially evolving turbulence and the applicability of Taylor's hypothesis in compressible flow

    NASA Technical Reports Server (NTRS)

    Lee, Sangsan; Lele, Sanjiva K.; Moin, Parviz

    1992-01-01

    For the numerical simulation of inhomogeneous turbulent flows, a method is developed for generating stochastic inflow boundary conditions with a prescribed power spectrum. Turbulence statistics from spatial simulations using this method with a low fluctuation Mach number are in excellent agreement with the experimental data, which validates the procedure. Turbulence statistics from spatial simulations are also compared to those from temporal simulations using Taylor's hypothesis. Statistics such as turbulence intensity, vorticity, and velocity derivative skewness compare favorably with the temporal simulation. However, the statistics of dilatation show a significant departure from those obtained in the temporal simulation. To directly check the applicability of Taylor's hypothesis, space-time correlations of fluctuations in velocity, vorticity, and dilatation are investigated. Convection velocities based on vorticity and velocity fluctuations are computed as functions of the spatial and temporal separations. The profile of the space-time correlation of dilatation fluctuations is explained via a wave propagation model.

  14. Assessing spatial resolution versus sensitivity from laser speckle contrast imaging: application to frequency analysis.

    PubMed

    Bricq, Stéphanie; Mahé, Guillaume; Rousseau, David; Humeau-Heurtier, Anne; Chapeau-Blondeau, François; Varela, Julio Rojas; Abraham, Pierre

    2012-10-01

    For blood perfusion monitoring, laser speckle contrast (LSC) imaging is a recent non-contact technique that has the characteristic of delivering noise-like speckled images. To exploit LSC images for quantitative physiological measurements, we developed an approach that implements controlled spatial averaging to reduce the detrimental impact of the noise and improve measurement sensitivity. By this approach, spatial resolution and measurement sensitivity can be traded-off in a flexible way depending on the quantitative prospect of the study. As an application, detectability of the cardiac activity from LSC images of forearm using power spectrum analysis is studied through the construction of spatial activity maps offering a window on the blood flow perfusion and its regional distribution. Comparisons with results obtained with signals of laser Doppler flowmetry probes are performed. PMID:22644256

  15. The application of spatial analysis based on rough set theory and hierarchical analysis

    NASA Astrophysics Data System (ADS)

    Lin, Zhiyong; Liang, Shuang

    2009-10-01

    As the development of the theory and technology of geographical information, Geographical Information System (GIS) has been widely applied in variety of industries. It usually refers to the analytical problem of multi-factor in GIS thematic application. In this field, the determination of factors' weight is a common and important problem. It actually deals the data when processing the spatial analysis applying GIS, for example, according to the importance of some factor, assign some value to it then process spatial overlay operation using the values and finally conclude some evaluation or result. In reality, there are many factors that affect the some kind of evaluation. Usually, we choose several more important factors as the evaluation criterion in order to make convenient for research. Then we assign some weight values to these factors and process spatial analysis then conclude some decision or evaluation to make support for decision-making. We can choose the factors that can make more impaction on the evaluation or decision-making using the method of Analytical Hierarchy Process (AHP). However, it has strong subjectivity of the factors' weight values assigned by this method. Rough set theory, which can effectively remove the impaction made by artificial factors, can make up the deficiency. It can make the spatial analysis more objective and more effective combining the two methods in GIS spatial analysis.

  16. Application of a Spatial Intelligent Decision System on Self-Rated Health Status Estimation.

    PubMed

    Calzada, Alberto; Liu, Jun; Wang, Hui; Nugent, Chris; Martinez, Luis

    2015-11-01

    Self- assessed general health status is a commonly-used survey technique since it can be used as a predictor for several public health risks such as mortality, deprivation, and fear of crime or poverty. Therefore, it is a useful alternative measure to help assessing the public health situation of a neighborhood or town, and can be utilized by authorities in many decision support situations related to public health, budget allocation and general policy-making, among others. It can be considered as spatial decision problems, since both data location and spatial relationships make a prominent impact during the decision making process. This paper utilizes a recently-developed spatial intelligent decision system, named, Spatial RIMER(+), to model the self-rated health estimation decision problem using real data in the areas of Northern Ireland, UK. The goal is to learn from past or partial observations on self-rated health status to predict its future or neighborhood behavior and reference it in the map. Three scenarios in line of this goal are discussed in details, i.e., estimation of unknown, downscaling, and predictions over time. They are used to demonstrate the flexibility and applicability of the spatial decision support system and their positive capabilities in terms of accuracy, efficiency and visualization. PMID:26330224

  17. Jackson State University's Center for Spatial Data Research and Applications: New facilities and new paradigms

    NASA Technical Reports Server (NTRS)

    Davis, Bruce E.; Elliot, Gregory

    1989-01-01

    Jackson State University recently established the Center for Spatial Data Research and Applications, a Geographical Information System (GIS) and remote sensing laboratory. Taking advantage of new technologies and new directions in the spatial (geographic) sciences, JSU is building a Center of Excellence in Spatial Data Management. New opportunities for research, applications, and employment are emerging. GIS requires fundamental shifts and new demands in traditional computer science and geographic training. The Center is not merely another computer lab but is one setting the pace in a new applied frontier. GIS and its associated technologies are discussed. The Center's facilities are described. An ARC/INFO GIS runs on a Vax mainframe, with numerous workstations. Image processing packages include ELAS, LIPS, VICAR, and ERDAS. A host of hardware and software peripheral are used in support. Numerous projects are underway, such as the construction of a Gulf of Mexico environmental data base, development of AI in image processing, a land use dynamics study of metropolitan Jackson, and others. A new academic interdisciplinary program in Spatial Data Management is under development, combining courses in Geography and Computer Science. The broad range of JSU's GIS and remote sensing activities is addressed. The impacts on changing paradigms in the university and in the professional world conclude the discussion.

  18. Transmission Phase Holography: Spatial-Mode Filter Design for Quantum Information Applications

    NASA Astrophysics Data System (ADS)

    Hillmer, Rachel; Barreiro, Julio; Kwiat, Paul

    2007-03-01

    Photon spatial modes offer access to promising new applications in quantum information because they provide a higher-dimensional basis set than the usual two-dimensional one associated with polarization. Downconversion experiments have demonstrated spatial-mode entanglement [1], and even hyperentanglement in polarization and spatial mode [2]. However optical elements currently lack the refinement necessary to perform efficient, high-fidelity operations using spatial modes. Holographic filters for Laguerre-Gaussian and Hermite-Gaussian laser modes can act as modes converters, and have long been studied (under the terms ``modans'' and ``kinoforms'') for use in electrical engineering applications [3,4]. Her we present analytical refinements and optimizations of these techniques, with predicted mode fidelities over 95% and diffraction efficiencies up to 98%. Results of our experimental implementions of these solutions are presented. [1] Walborn, S.P, et al, ``Entanglement and conservation of orbital angular momentum in spontaneous parametric down-conversion,'' Phys. Rev. A 69, 023811 (2004); [2] Barreiro, J.T. et al, ``Generation of Hyperentangled Photon Pairs,'' Phys. Rev. Lett. 95, 260501 (2005); [3] Soifer, V.A., ``Methods of Computer Design of Diffractive Optical Elements,'' John Wiley & Sons, Inc., 2002; [4] Golub, M. and Soifer, V., ``Laser Beam Mode Selection by Computer Generated Holograms,'' CRC Press, Inc., 1994.

  19. A spatially filtered multilevel model to account for spatial dependency: application to self-rated health status in South Korea

    PubMed Central

    2014-01-01

    Background This study aims to suggest an approach that integrates multilevel models and eigenvector spatial filtering methods and apply it to a case study of self-rated health status in South Korea. In many previous health-related studies, multilevel models and single-level spatial regression are used separately. However, the two methods should be used in conjunction because the objectives of both approaches are important in health-related analyses. The multilevel model enables the simultaneous analysis of both individual and neighborhood factors influencing health outcomes. However, the results of conventional multilevel models are potentially misleading when spatial dependency across neighborhoods exists. Spatial dependency in health-related data indicates that health outcomes in nearby neighborhoods are more similar to each other than those in distant neighborhoods. Spatial regression models can address this problem by modeling spatial dependency. This study explores the possibility of integrating a multilevel model and eigenvector spatial filtering, an advanced spatial regression for addressing spatial dependency in datasets. Methods In this spatially filtered multilevel model, eigenvectors function as additional explanatory variables accounting for unexplained spatial dependency within the neighborhood-level error. The specification addresses the inability of conventional multilevel models to account for spatial dependency, and thereby, generates more robust outputs. Results The findings show that sex, employment status, monthly household income, and perceived levels of stress are significantly associated with self-rated health status. Residents living in neighborhoods with low deprivation and a high doctor-to-resident ratio tend to report higher health status. The spatially filtered multilevel model provides unbiased estimations and improves the explanatory power of the model compared to conventional multilevel models although there are no changes in the

  20. High-Q polymer resonators with spatially controlled photo-functionalization for biosensing applications

    NASA Astrophysics Data System (ADS)

    Beck, Torsten; Mai, Martin; Grossmann, Tobias; Wienhold, Tobias; Hauser, Mario; Mappes, Timo; Kalt, Heinz

    2013-03-01

    We demonstrate the applicability of polymeric whispering gallery mode resonators fabricated on silicon as biosensors. Optical measurements on the passive resonators in the visible spectral range yield Q-factors as high as 1.3×107. Local, covalent surface functionalization, is achieved by spatially controlled UV-exposure of a derivative of the photoreactive crosslinker benzophenone. Protein detection is shown using the specific binding of the biotin-streptavidin system.

  1. Spatially controlled electro-stimulated DNA adsorption and desorption for biochip applications.

    PubMed

    Hook, Andrew L; Thissen, Helmut; Hayes, Jason P; Voelcker, Nicolas H

    2006-05-15

    The manipulation of biomolecules at solid/liquid interfaces is important for the enhanced performance of a number of biomedical devices, including biochips. This study focuses on the spatial control of surface interactions of DNA as well as the electro-stimulated adsorption and desorption of DNA by appropriate surface modification of highly doped p-type silicon. Surface modification by plasma polymerisation of allylamine resulted in a surface that supported DNA adsorption and sustained cell attachment. Subsequent high-density grafting of poly(ethylene oxide) formed a low fouling layer resistant to biomolecule adsorption and cell attachment. Spatially controlled excimer laser ablation of the surface produced patterns of re-exposed plasma polymer with high-resolution. On patterned surfaces, preferential electro-stimulated adsorption of DNA to the allylamine plasma polymer surface and subsequent desorption by the application of a negative bias was observed. Furthermore, the concept presented here was investigated for use in transfection chips. Cell culture experiments with human embryonic kidney cells, using the expression of green fluorescent protein as a reporter, demonstrated efficient and controlled transfection of cells. Electro-stimulated desorption of DNA was shown to yield significantly enhanced solid phase transfection efficiencies to values of up to 30%. The ability to spatially control DNA adsorption combined with the ability to control the binding and release of DNA by application of a controlled voltage enables an advanced level of control over DNA bioactivity on solid substrates and lends itself to biochip applications. PMID:16303297

  2. Displaying R spatial statistics on Google dynamic maps with web applications created by Rwui

    PubMed Central

    2012-01-01

    Background The R project includes a large variety of packages designed for spatial statistics. Google dynamic maps provide web based access to global maps and satellite imagery. We describe a method for displaying directly the spatial output from an R script on to a Google dynamic map. Methods This is achieved by creating a Java based web application which runs the R script and then displays the results on the dynamic map. In order to make this method easy to implement by those unfamiliar with programming Java based web applications, we have added the method to the options available in the R Web User Interface (Rwui) application. Rwui is an established web application for creating web applications for running R scripts. A feature of Rwui is that all the code for the web application being created is generated automatically so that someone with no knowledge of web programming can make a fully functional web application for running an R script in a matter of minutes. Results Rwui can now be used to create web applications that will display the results from an R script on a Google dynamic map. Results may be displayed as discrete markers and/or as continuous overlays. In addition, users of the web application may select regions of interest on the dynamic map with mouse clicks and the coordinates of the region of interest will automatically be made available for use by the R script. Conclusions This method of displaying R output on dynamic maps is designed to be of use in a number of areas. Firstly it allows statisticians, working in R and developing methods in spatial statistics, to easily visualise the results of applying their methods to real world data. Secondly, it allows researchers who are using R to study health geographics data, to display their results directly onto dynamic maps. Thirdly, by creating a web application for running an R script, a statistician can enable users entirely unfamiliar with R to run R coded statistical analyses of health geographics

  3. Application of Alignment Methodologies to Spatial Ontologies in the Hydro Domain

    NASA Astrophysics Data System (ADS)

    Lieberman, J. E.; Cheatham, M.; Varanka, D.

    2015-12-01

    Ontologies are playing an increasing role in facilitating mediation and translation between datasets representing diverse schemas, vocabularies, or knowledge communities. This role is relatively straightforward when there is one ontology comprising all relevant common concepts that can be mapped to entities in each dataset. Frequently, one common ontology has not been agreed to. Either each dataset is represented by a distinct ontology, or there are multiple candidates for commonality. Either the one most appropriate (expressive, relevant, correct) ontology must be chosen, or else concepts and relationships matched across multiple ontologies through an alignment process so that they may be used in concert to carry out mediation or other semantic operations. A resulting alignment can be effective to the extent that entities in in the ontologies represent differing terminology for comparable conceptual knowledge. In cases such as spatial ontologies, though, ontological entities may also represent disparate conceptualizations of space according to the discernment methods and application domains on which they are based. One ontology's wetland concept may overlap in space with another ontology's recharge zone or wildlife range or water feature. In order to evaluate alignment with respect to spatial ontologies, alignment has been applied to a series of ontologies pertaining to surface water that are used variously in hydrography (characterization of water features), hydrology (study of water cycling), and water quality (nutrient and contaminant transport) application domains. There is frequently a need to mediate between datasets in each domain in order to develop broader understanding of surface water systems, so there is a practical as well theoretical value in the alignment. From a domain expertise standpoint, the ontologies under consideration clearly contain some concepts that are spatially as well as conceptually identical and then others with less clear

  4. A Visible, Spatially-Modulated Imaging Fourier Transform Spectrometer (SMIFTS) for Astronomical Applications

    NASA Astrophysics Data System (ADS)

    Rafert, J. B.; Holbert, E. T.; Rusk, E. T.; Durham, S. E.; Caudill, E.; Keating, D.; Newby, H.

    1992-12-01

    We have constructed several visible, Spatially-Modulated Imaging Fourier Transform Spectrometers (SMIFTS) for spatially resolved spectral imaging in the visible wavelength region based on work by several authors including Yoshihara and Kitade (1967), Okamoto et al. (1984), Barnes (1985) and Smith and Schempp (1991). Our spectrometers require no moving parts, are compact and enjoy a number of advantages over the other spectral data collection technologies. The unique combination of characteristics define an important niche for astronomical, remote sensing, and reconnaissance spectral data acquisition. Our SMIFTS simultaneously acquires hundreds or thousands of spectral bands for hundreds or thousands of spectral channesl. This type of sensor has been called a "hyperspectral" sensor to emphasize the major quantitative difference between this type of sensor and multispectral imagers which collect only a few spectral bands. The SMIFTS consists of input optics (a telescope), a field limiting aperture, a beamsplitter which divides the input beam into two paths, two mirrors which redirect the split beams through the same path, a collimating lens which forms the interferogram of the input aperture on the detector plane, and a cylindrical imaging lens. Thus on the detector array one axis contains spatial information and the other axis contains the spectral information for each point of the spatial axis. The result of this arrangement is that each row of the detector array contains the interferogram of the corresponding point on the aperture or slit. This slit can be fixed upon the target, or the slit can be scanned across the target to build up a second axis of spatial information resulting in a data set with four dimensions: two spatial, one spectral, and one temporal. We present sample data for both astronomical and remote sensing applications taken with the Malabar SMIFTS. Barnes, T.H. "Photodiode Array Fourier Transform Spectrometer with Improved Dynamic Range", Appl

  5. The market value of cultural heritage in urban areas: an application of spatial hedonic pricing

    NASA Astrophysics Data System (ADS)

    Lazrak, Faroek; Nijkamp, Peter; Rietveld, Piet; Rouwendal, Jan

    2014-01-01

    The current literature often values intangible goods like cultural heritage by applying stated preference methods. In recent years, however, the increasing availability of large databases on real estate transactions and listed prices has opened up new research possibilities and has reduced various existing barriers to applications of conventional (spatial) hedonic analysis to the real estate market. The present paper provides one of the first applications using a spatial autoregressive model to investigate the impact of cultural heritage—in particular, listed buildings and historic-cultural sites (or historic landmarks)—on the value of real estate in cities. In addition, this paper suggests a novel way of specifying the spatial weight matrix—only prices of sold houses influence current price—in identifying the spatial dependency effects between sold properties. The empirical application in the present study concerns the Dutch urban area of Zaanstad, a historic area for which over a long period of more than 20 years detailed information on individual dwellings, and their market prices are available in a GIS context. In this paper, the effect of cultural heritage is analysed in three complementary ways. First, we measure the effect of a listed building on its market price in the relevant area concerned. Secondly, we investigate the value that listed heritage has on nearby property. And finally, we estimate the effect of historic-cultural sites on real estate prices. We find that, to purchase a listed building, buyers are willing to pay an additional 26.9 %, while surrounding houses are worth an extra 0.28 % for each additional listed building within a 50-m radius. Houses sold within a conservation area appear to gain a premium of 26.4 % which confirms the existence of a `historic ensemble' effect.

  6. Instability in spatial error models: an application to the hypothesis of convergence in the European case

    NASA Astrophysics Data System (ADS)

    Mur, Jesús; López, Fernando; Angulo, Ana

    2010-09-01

    This paper focuses on the hypothesis of stability in the mechanisms of spatial dependence that are usually employed in spatial econometric models. We propose a specification strategy for which the first step is to solve a local estimation algorithm, called the Zoom estimation. The aim of this stage is to detect problems of heterogeneity in the parameters and to identify the regimes. Then we resort to a battery of formal Lagrange Multipliers to test the assumption of stability in the processes of spatial dependence. The alternative hypothesis consists of the existence of several regimes in these parameters. A small Monte Carlo serves to confirm the behaviour of this strategy in a context of finite size samples. As an illustration, we solve an application to the case of the hypothesis of convergence for the per capita income in the European regions. Our results reveal the existence of a strong Centre-Periphery dichotomy in which instability extends to all the elements (coefficients of regression as well as parameters of spatial dependence) that intervene in a classical conditional β-convergence model.

  7. Binomial tau-leap spatial stochastic simulation algorithm for applications in chemical kinetics.

    PubMed

    Marquez-Lago, Tatiana T; Burrage, Kevin

    2007-09-14

    In cell biology, cell signaling pathway problems are often tackled with deterministic temporal models, well mixed stochastic simulators, and/or hybrid methods. But, in fact, three dimensional stochastic spatial modeling of reactions happening inside the cell is needed in order to fully understand these cell signaling pathways. This is because noise effects, low molecular concentrations, and spatial heterogeneity can all affect the cellular dynamics. However, there are ways in which important effects can be accounted without going to the extent of using highly resolved spatial simulators (such as single-particle software), hence reducing the overall computation time significantly. We present a new coarse grained modified version of the next subvolume method that allows the user to consider both diffusion and reaction events in relatively long simulation time spans as compared with the original method and other commonly used fully stochastic computational methods. Benchmarking of the simulation algorithm was performed through comparison with the next subvolume method and well mixed models (MATLAB), as well as stochastic particle reaction and transport simulations (CHEMCELL, Sandia National Laboratories). Additionally, we construct a model based on a set of chemical reactions in the epidermal growth factor receptor pathway. For this particular application and a bistable chemical system example, we analyze and outline the advantages of our presented binomial tau-leap spatial stochastic simulation algorithm, in terms of efficiency and accuracy, in scenarios of both molecular homogeneity and heterogeneity. PMID:17867731

  8. Quantitative characterization of the spatial distribution of particles in materials: Application to materials processing

    NASA Technical Reports Server (NTRS)

    Parse, Joseph B.; Wert, J. A.

    1991-01-01

    Inhomogeneities in the spatial distribution of second phase particles in engineering materials are known to affect certain mechanical properties. Progress in this area has been hampered by the lack of a convenient method for quantitative description of the spatial distribution of the second phase. This study intends to develop a broadly applicable method for the quantitative analysis and description of the spatial distribution of second phase particles. The method was designed to operate on a desktop computer. The Dirichlet tessellation technique (geometrical method for dividing an area containing an array of points into a set of polygons uniquely associated with the individual particles) was selected as the basis of an analysis technique implemented on a PC. This technique is being applied to the production of Al sheet by PM processing methods; vacuum hot pressing, forging, and rolling. The effect of varying hot working parameters on the spatial distribution of aluminum oxide particles in consolidated sheet is being studied. Changes in distributions of properties such as through-thickness near-neighbor distance correlate with hot-working reduction.

  9. Spatial variability of soil potassium in sugarcane areas subjected to the application of vinasse.

    PubMed

    De Carvalho, Laércio A; Meurer, Ismael; Da Silva Junior, Carlos A; Santos, Cristiane F B; Libardi, Paulo L

    2014-12-01

    When deposited on land the vinasse can promote improvement in fertility, however, often fertilizer application occurs in areas considered homogeneous, without taking into account the variability of the soil. The objective of this study was to evaluate the effect of vinasse application on potassium content in two classes of soils cultivated with sugarcane, and characterize the spatial variability of soil using geostatistical techniques. In the 2010 and 2011 crop year, soil samples were collected from an experimental grid at 0-0.2 and 0.2-0.4 m depth in three soils cultivated with sugarcane, totaling 90 samplings in each grid, for the determination of pH, calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P), aluminum (Al) and potential acidity (H + Al). The data have been submitted to analysis of descriptive statistics and the K attribute was subjected to geostatistical analysis. The coefficient of variation indicated medium and high variability of K for the three soils. The results showed that the spatial dependence of K increased in depth to FRce and decreased to PHlv, indicating that the attribute could have followed the pattern of distribution of clay in depth. The investigation of the spatial variability of K on the surface and subsurface soils provided the definition of management zones with different levels of fertility, which can be organized into sub-areas for a more efficient management of the resources and the environment. PMID:25590735

  10. [Application of Land-use Regression Models in Spatial-temporal Differentiation of Air Pollution].

    PubMed

    Wu, Jian-sheng; Xie, Wu-dan; Li, Jia-cheng

    2016-02-15

    With the rapid development of urbanization, industrialization and motorization, air pollution has become one of the most serious environmental problems in our country, which has negative impacts on public health and ecological environment. LUR model is one of the common methods simulating spatial-temporal differentiation of air pollution at city scale. It has broad application in Europe and North America, but not really in China. Based on many studies at home and abroad, this study started with the main steps to develop LUR model, including obtaining the monitoring data, generating variables, developing models, model validation and regression mapping. Then a conclusion was drawn on the progress of LUR models in spatial-temporal differentiation of air pollution. Furthermore, the research focus and orientation in the future were prospected, including highlighting spatial-temporal differentiation, increasing classes of model variables and improving the methods of model development. This paper was aimed to popularize the application of LUR model in China, and provide a methodological basis for human exposure, epidemiologic study and health risk assessment. PMID:27363125

  11. Applications of Spatial Technology in Schistosomiasis Control Programme in The People's Republic of China.

    PubMed

    Wang, X-Y; He, J; Yang, K; Liang, S

    2016-01-01

    Schistosomiasis, as the important parasitic disease, has caused serious threats to human health globally. The People's Republic of China has acquired significant achievements based on large-scale interventions and innovational technology. The spatial technology was introduced in 1980s and widely used in the study and control of schistosomiasis in The People's Republic of China. This chapter reviews the progress and application of spatial technology in schistosomiasis control by analysing the spatiotemporal pattern of and the impact of ecological changes on schistosomiasis transmission, which have provided the information to design and select the control strategy, and assisted the establishment of the monitoring and early warning system in The People's Republic of China, especially in the marshland and mountainous regions. PMID:27137446

  12. Transformative Relation of Kinematical Descriptive Quantities Defined by Different Spatial Referential Frame, Its Property and Application

    NASA Astrophysics Data System (ADS)

    Luo, Ji

    2012-08-01

    Quantitative transformations between corresponding kinetic quantities defined by any two spatial referential frames, whose relative kinematics relations (purely rotational and translational movement) are known, are presented based on necessarily descriptive definitions of the fundamental concepts (instant, time, spatial referential frame that distinguishes from Maths. Coordination, physical point) had being clarified by directly empirical observation with artificially descriptive purpose. Inductive investigation of the transformation reveals that all physical quantities such as charge, temperature, time, volume, length, temporal rate of the quantities and relations like temporal relation between signal source and observer as such are independent to spatial frames transformation except above kinematical quantities transformations, kinematics related dynamics such as Newton ’ s second law existing only in inertial frames and exchange of kinetic energy of mass being valid only in a selected inertial frame. From above bas is, we demonstrate a series of inferences and applications such as phase velocity of light being direct respect to medium (including vacuum) rather than to the frame, using spatial referential frame to describe any measurable field (electric field, magnetic field, gravitational field) and the field ’ s variation; and have tables to contrast and evaluate all aspects of those hypotheses related with spacetime such as distorted spacetime around massive stellar, four dimension spacetime, gravitational time dilation and non - Euclid geometry with new one. The demonstration strongly suggests all the hypotheses are invalid in capable tested concepts ’ meaning and relations. The conventional work on frame transformation and its property, hypothesized by Voigt, Heaviside, Lorentz, Poincare and Einstein a century ago with some mathematical speculation lacking rigorous definition of the fundamental concepts such as instant, time, spatial reference

  13. High dimensional spatial modeling of extremes with applications to United States Rainfalls

    NASA Astrophysics Data System (ADS)

    Zhou, Jie

    2007-12-01

    data sets with extreme value distributions involved. One of the main outcomes of this model is for producing N-year return values and return years for a given value for precipitation at a single location given climate model projections based on a grid. This is very important, because in many applications, detailed precipitation information on pointwise locations is more important that predictions averaged over grids. The second model can be applied to those large data sets and is based on transformed Gaussian processes. These processes are thresholded due to the emphasis on rainfall extremes. Keywords. Block Circulant Matrix; Extreme value theory; Fast Fourier Transform; Generalized Linear Mixed Model; Kriging; Markov Chain Monte Carlo; Spectral Representation; Spatial statistics

  14. Scalable digital spatial light modulator-micromesh heterostructures for real time wave optical applications.

    PubMed

    Jeong, Hoon; Choi, Jaewu

    2014-09-22

    For large-scale real time wave optical applications, we propose and demonstrate scalable simple digital spatial light modulator (SLM)-micromesh (μM) heterostructures, which fully harness ubiquitous well developed consumer information displays for real time large-scale SLMs and advanced patterning technologies for promoting the wave optical properties of SLMs of any size. Weakly diffractive projection mode large-scale SLMs with poor demultiplexity are transformed to highly diffractive mode heterostructures with fine patterned micromeshes as efficient demultiplexers or wave optical promoters. As a result, diffraction efficiency, diffraction angle, demultiplexity, multiplexity, reconstructed image quality and numbers of visibly reconstructed images largely increase even though the pixel pitches of the employed SLMs are many orders of magnitude larger than the wavelength of the illuminating light. The approach shown in this study can be applicable even for any sized weakly diffractive SLMs, and can simultaneously increase the effective spatial bandwidth and the physical dimension required for their wave optical applications. This can't be achieved by presently available SLMs alone. PMID:25321757

  15. Cherenkov detectors for spatial imaging applications using discrete-energy photons

    NASA Astrophysics Data System (ADS)

    Rose, Paul B.; Erickson, Anna S.

    2016-08-01

    Cherenkov detectors can offer a significant advantage in spatial imaging applications when excellent timing response, low noise and cross talk, large area coverage, and the ability to operate in magnetic fields are required. We show that an array of Cherenkov detectors with crude energy resolution coupled with monochromatic photons resulting from a low-energy nuclear reaction can be used to produce a sharp image of material while providing large and inexpensive detector coverage. The analysis of the detector response to relative transmission of photons with various energies allows for reconstruction of material's effective atomic number further aiding in high-Z material identification.

  16. Application of Image Analysis for Characterization of Spatial Arrangements of Features in Microstructure

    NASA Technical Reports Server (NTRS)

    Louis, Pascal; Gokhale, Arun M.

    1995-01-01

    A number of microstructural processes are sensitive to the spatial arrangements of features in microstructure. However, very little attention has been given in the past to the experimental measurements of the descriptors of microstructural distance distributions due to the lack of practically feasible methods. We present a digital image analysis procedure to estimate the micro-structural distance distributions. The application of the technique is demonstrated via estimation of K function, radial distribution function, and nearest-neighbor distribution function of hollow spherical carbon particulates in a polymer matrix composite, observed in a metallographic section.

  17. Spatial-scanning hyperspectral imaging probe for bio-imaging applications

    NASA Astrophysics Data System (ADS)

    Lim, Hoong-Ta; Murukeshan, Vadakke Matham

    2016-03-01

    The three common methods to perform hyperspectral imaging are the spatial-scanning, spectral-scanning, and snapshot methods. However, only the spectral-scanning and snapshot methods have been configured to a hyperspectral imaging probe as of today. This paper presents a spatial-scanning (pushbroom) hyperspectral imaging probe, which is realized by integrating a pushbroom hyperspectral imager with an imaging probe. The proposed hyperspectral imaging probe can also function as an endoscopic probe by integrating a custom fabricated image fiber bundle unit. The imaging probe is configured by incorporating a gradient-index lens at the end face of an image fiber bundle that consists of about 50 000 individual fiberlets. The necessary simulations, methodology, and detailed instrumentation aspects that are carried out are explained followed by assessing the developed probe's performance. Resolution test targets such as United States Air Force chart as well as bio-samples such as chicken breast tissue with blood clot are used as test samples for resolution analysis and for performance validation. This system is built on a pushbroom hyperspectral imaging system with a video camera and has the advantage of acquiring information from a large number of spectral bands with selectable region of interest. The advantages of this spatial-scanning hyperspectral imaging probe can be extended to test samples or tissues residing in regions that are difficult to access with potential diagnostic bio-imaging applications.

  18. A Novel Artificial Immune Algorithm for Spatial Clustering with Obstacle Constraint and Its Applications

    PubMed Central

    Sun, Liping; Luo, Yonglong; Ding, Xintao; Zhang, Ji

    2014-01-01

    An important component of a spatial clustering algorithm is the distance measure between sample points in object space. In this paper, the traditional Euclidean distance measure is replaced with innovative obstacle distance measure for spatial clustering under obstacle constraints. Firstly, we present a path searching algorithm to approximate the obstacle distance between two points for dealing with obstacles and facilitators. Taking obstacle distance as similarity metric, we subsequently propose the artificial immune clustering with obstacle entity (AICOE) algorithm for clustering spatial point data in the presence of obstacles and facilitators. Finally, the paper presents a comparative analysis of AICOE algorithm and the classical clustering algorithms. Our clustering model based on artificial immune system is also applied to the case of public facility location problem in order to establish the practical applicability of our approach. By using the clone selection principle and updating the cluster centers based on the elite antibodies, the AICOE algorithm is able to achieve the global optimum and better clustering effect. PMID:25435862

  19. Application of spatial frequency response as a criterion for evaluating thermal imaging camera performance

    NASA Astrophysics Data System (ADS)

    Lock, Andrew; Amon, Francine

    2008-04-01

    Police, firefighters, and emergency medical personnel are examples of first responders that are utilizing thermal imaging cameras in a very practical way every day. However, few performance metrics have been developed to assist first responders in evaluating the performance of thermal imaging technology. This paper describes one possible metric for evaluating spatial resolution using an application of Spatial Frequency Response (SFR) calculations for thermal imaging. According to ISO 12233, the SFR is defined as the integrated area below the Modulation Transfer Function (MTF) curve derived from the discrete Fourier transform of a camera image representing a knife-edge target. This concept is modified slightly for use as a quantitative analysis of the camera's performance by integrating the area between the MTF curve and the camera's characteristic nonuniformity, or noise floor, determined at room temperature. The resulting value, which is termed the Effective SFR, can then be compared with a spatial resolution value obtained from human perception testing of task specific situations to determine the acceptability of the performance of thermal imaging cameras. The testing procedures described herein are being developed as part of a suite of tests for possible inclusion into a performance standard on thermal imaging cameras for first responders.

  20. Optimal Spatial Resolution of Omnidirectional Imaging Systems for Pipe Inspection Applications

    NASA Astrophysics Data System (ADS)

    Dehghan Tezerjani, Abbasali; Mehrandezh, Mehran; Paranjape, Raman

    2015-10-01

    Achieving optimal spatial resolution in imaging systems plays a major role in the design of vision-based industrial inspection tools. Single-view omnidirectional imaging systems provide a cost-effective and computationally-traceable solution for real-time inspection of infrastructure with a favorable size factor. We formulate, for the first time, the spatial cylindrical resolution of omnidirectional Catadioptric and Dioptric imaging systems with the focus on pipe inspection applications. We also provide a design guideline to achieve the highest resolution in these systems. First, we deliver a comprehensive study on optimal resolution in Catadioptric imaging systems which consist of a perspective pinhole camera, a collimated laser as the light source, and a reflective surface (i.e., hyperbolic mirror). Variation of the spatial resolution in terms of the camera's focal length, the mirror curvature, and the relative position between the laser projector and the camera is fully investigated via simulation and experiments. Also, the optimal resolution in Dioptric systems, which consist of a camera with compound refractive lenses (i.e., fish-eye lens) is studied and compared with that in Catadioptric systems. Tests were conducted on a 40-cm-diameter PVC pipe in a controlled laboratory environment.

  1. 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

  2. A hierarchical spatial model of avian abundance with application to Cerulean Warblers

    USGS Publications Warehouse

    Thogmartin, W.E.; Sauer, J.R.; Knutson, M.G.

    2004-01-01

    is counts, such as animal counts, activity (e.g.,nest) counts, or species richness. The most noteworthy practical application of this spatial modeling approach is the ability to map relative species abundance. The functional relationships that we elucidated for the Cerulean Warbler provide a basis for the development of management programs and may serve to focus management and monitoring on areas and habitat variables important to Cerulean Warblers.

  3. Lack of spatial and behavioral responses to immunocontraception application in African elephants (Loxodonta africana).

    PubMed

    Delsink, Audrey K; Kirkpatrick, Jay; van Altena, J J; Bertschinger, Henk J; Ferreira, Sam M; Slotow, Robert

    2013-12-01

    Opinions are divided as to whether human intervention to control elephant (Loxodonta africana) population growth is desirable, partly because of elephant welfare concerns. Female contraception through immunization with porcine zona pellucida (PZP) proteins is viable. The effects of sustained use and application of the PZP vaccine on elephant behavioral and spatial responses were examined by evaluating herd ranging, fission-fusion dynamics, association patterns, and reproductive and sexual behaviors. Minimal change was anticipated as a result of long calf dependence on and association with cows, a reduced but not indefinite 0% growth rate and the known mechanism of action of PZP vaccines, and minimal expected change in resource requirements necessitating behavioral or spatial use adaptations. Although behavioral effects identified in previous hormonal contraceptive trials were evident, it was demonstrated that immunocontraception caused no prolonged behavioral, social, or spatial changes over the 11-yr study period. Individually identified elephants were monitored from 1999 to 2011. Minimal, short-term social disruption, with temporary changes to the herds' core ranges, was observed during the annual treatment events, particularly in the first three treatment years, when vaccinations were conducted exclusively from the ground. Thereafter, when vaccinations were conducted aerially, minor disruptions were confined to the morning of administration only. Despite sustained treatments resulting in demographic changes of fewer calves being born, treatments did not alter spatial range use, and no adverse interherd-intraherd relations were observed. Similarly, resource requirements did not change as calving still occurred, although in fewer numbers. It was concluded that PZP immunocontraception has no detectable behavioral or social consequences in elephants over the course of 11 yr, providing a convincing argument for the use of sustained immunocontraception in the medium

  4. Towards a typology of spatial relations and properties for urban applications

    NASA Astrophysics Data System (ADS)

    Bucher, B.; Falquet, G.; Clementini, E.; Sester, M.

    2012-10-01

    Relations that occur between features located in space-like the fact that a street is surrounded by very high buildings, that an airport is close to a city- as well as spatial properties of features-like the height and width of a door- play an important role for many urban applications. Digital models of cities can assist in the evaluation of these relations and properties either through visualisation or through computation, mainly based on geometrical information. Hence, considering the objective of explaining to potential users of these city models what useful information they can derive from these data and how, a possible way to address this objective lies in the usage of a pivot model composed of relevant spatial properties and relations, connected to information meaningful to the user and connected to the possible computation of them on available data. This paper firstly sets the ground for a typology of such relevant relations and properties that are shared by different applications and that can be derived/approximated from existing data. It then proposes a model to describe these properties and relations and connect them to their possible computation based on data (2D or 3D). An important aspect of this model is to distinguish between a conceptual layer where relations occur between "real world" features and an implementation layer where they are calculated based on database features and geometries.

  5. From high spatial resolution imagery to spatial indicators : Application for hydromorphy follow-up on Bourgneuf wetland

    NASA Astrophysics Data System (ADS)

    Bailly, J. S.; Puech, C.; Lukac, F.; Massé, J.

    2003-04-01

    On Atlantic coastal wetlands, the understanding of hydrological processes may refer to hydraulic surface structures characterization as small ditches or channels networks, permanent and temporary water bodies. Moreover to improve the understanding, this characerization should be realized regarding different seasons and different spatial scales: elementary parcel, managment unit and whole wetland scales. In complement to usual observations on a few local ground points, high spatial resolution remote sensing may be a good information support for extraction and characterization on elementary objects, especially water bodies, permanents or temporary ones and ditches. To carry out a floow-up on wetlands, a seasonal image acquisition rate, reachable from most of satelite systems, is in that case informative for hydrological needs. In this work, georeferencing methods on openfield wetlands have been handled with care in order to use diachronic images or combined geographical data; lack of relief, short vegetation and well structured landscape make this preprocess easier in comparison to other landscape situations. In this presentation we focus on spatial hydromorphy parameters constructed from images with specific processes. Especially, hydromorphy indicators for parcels or managment units have been developped using an IRC winter-spring-summer metric resolution set of images: these descriptors are based on water areas evolution or hydrophyl vegetations presence traducing hydrodynamic submersion behaviour in temporary water bodies. An other example presents a surface water network circulation indicator elaborated on IRC aerial photography combined with vectorized geographic database. This indicator is based on ditches width and vegetation presence : a specific process uses vectorized geo data set to define transects across ditches on which classified image analysis is carried out (supervised classification). These first results proposing hydromorphy descriptors from very

  6. Development of spatial density maps based on geoprocessing web services: application to tuberculosis incidence in Barcelona, Spain

    PubMed Central

    2011-01-01

    Background Health professionals and authorities strive to cope with heterogeneous data, services, and statistical models to support decision making on public health. Sophisticated analysis and distributed processing capabilities over geocoded epidemiological data are seen as driving factors to speed up control and decision making in these health risk situations. In this context, recent Web technologies and standards-based web services deployed on geospatial information infrastructures have rapidly become an efficient way to access, share, process, and visualize geocoded health-related information. Methods Data used on this study is based on Tuberculosis (TB) cases registered in Barcelona city during 2009. Residential addresses are geocoded and loaded into a spatial database that acts as a backend database. The web-based application architecture and geoprocessing web services are designed according to the Representational State Transfer (REST) principles. These web processing services produce spatial density maps against the backend database. Results The results are focused on the use of the proposed web-based application to the analysis of TB cases in Barcelona. The application produces spatial density maps to ease the monitoring and decision making process by health professionals. We also include a discussion of how spatial density maps may be useful for health practitioners in such contexts. Conclusions In this paper, we developed web-based client application and a set of geoprocessing web services to support specific health-spatial requirements. Spatial density maps of TB incidence were generated to help health professionals in analysis and decision-making tasks. The combined use of geographic information tools, map viewers, and geoprocessing services leads to interesting possibilities in handling health data in a spatial manner. In particular, the use of spatial density maps has been effective to identify the most affected areas and its spatial impact. This

  7. Active crop canopy sensor optimal spatial scale for in-season variable-rate nitrogen application in corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Active crop canopy reflectance sensors have shown to be an efficient method for assessing spatially-variable crop nitrogen (N) need and controlling remedial in-season N applications in wheat. Recently, these sensors have been studied for N application in corn. This study will be conducted during the...

  8. Using GIS to generate spatially balanced random survey designs for natural resource applications.

    PubMed

    Theobald, David M; Stevens, Don L; White, Denis; Urquhart, N Scott; Olsen, Anthony R; Norman, John B

    2007-07-01

    Sampling of a population is frequently required to understand trends and patterns in natural resource management because financial and time constraints preclude a complete census. A rigorous probability-based survey design specifies where to sample so that inferences from the sample apply to the entire population. Probability survey designs should be used in natural resource and environmental management situations because they provide the mathematical foundation for statistical inference. Development of long-term monitoring designs demand survey designs that achieve statistical rigor and are efficient but remain flexible to inevitable logistical or practical constraints during field data collection. Here we describe an approach to probability-based survey design, called the Reversed Randomized Quadrant-Recursive Raster, based on the concept of spatially balanced sampling and implemented in a geographic information system. This provides environmental managers a practical tool to generate flexible and efficient survey designs for natural resource applications. Factors commonly used to modify sampling intensity, such as categories, gradients, or accessibility, can be readily incorporated into the spatially balanced sample design. PMID:17546523

  9. Early non-destructive biofouling detection and spatial distribution: Application of oxygen sensing optodes.

    PubMed

    Farhat, N M; Staal, M; Siddiqui, A; Borisov, S M; Bucs, Sz S; Vrouwenvelder, J S

    2015-10-15

    Biofouling is a serious problem in reverse osmosis/nanofiltration (RO/NF) applications, reducing membrane performance. Early detection of biofouling plays an essential role in an adequate anti-biofouling strategy. Presently, fouling of membrane filtration systems is mainly determined by measuring changes in pressure drop, which is not exclusively linked to biofouling. Non-destructive imaging of oxygen concentrations (i) is specific for biological activity of biofilms and (ii) may enable earlier detection of biofilm accumulation than pressure drop. The objective of this study was to test whether transparent luminescent planar O2 optodes, in combination with a simple imaging system, can be used for early non-destructive biofouling detection. This biofouling detection is done by mapping the two-dimensional distribution of O2 concentrations and O2 decrease rates inside a membrane fouling simulator (MFS). Results show that at an early stage, biofouling development was detected by the oxygen sensing optodes while no significant increase in pressure drop was yet observed. Additionally, optodes could detect spatial heterogeneities in biofouling distribution at a micro scale. Biofilm development started mainly at the feed spacer crossings. The spatial and quantitative information on biological activity will lead to better understanding of the biofouling processes, contributing to the development of more effective biofouling control strategies. PMID:26117369

  10. Fiber-Based, Spatially and Temporally Shaped Picosecond UV Laser for Advanced RF Gun Applications

    SciTech Connect

    Shverdin, M Y; Anderson, S G; Betts, S M; Gibson, D J; Hartemann, F V; Hernandez, J E; Johnson, M; Jovanovic, I; Messerly, M; Pruet, J; Tremaine, A M; McNabb, D P; Siders, C W; Barty, C J

    2007-06-08

    The fiber-based, spatially and temporally shaped, picosecond UV laser system described here has been specifically designed for advanced rf gun applications, with a special emphasis on the production of high-brightness electron beams for free-electron lasers and Compton scattering light sources. The laser pulse can be shaped to a flat-top in both space and time with a duration of 10 ps at full width of half-maximum (FWHM) and rise and fall times under 1 ps. The expected pulse energy is 50 {micro}J at 261.75 nm and the spot size diameter of the beam at the photocathode is 2 mm. A fiber oscillator and amplifier system generates a chirped pump pulse at 1047 nm; stretching is achieved in a chirped fiber Bragg grating. A single multi-layer dielectric grating based compressor recompresses the input pulse to 250 fs FWHM and a two stage harmonic converter frequency quadruples the beam. Temporal shaping is achieved with a Michelson-based ultrafast pulse stacking device with nearly 100% throughput. Spatial shaping is achieved by truncating the beam at the 20% energy level with an iris and relay-imaging the resulting beam profile onto the photocathode. The integration of the system, as well as preliminary laser measurements will be presented.

  11. [Applicability analysis of spatially explicit model of leaf litter in evergreen broad-leaved forests].

    PubMed

    Zhao, Qing-Qing; Liu, He-Ming; Jonard, Mathieu; Wang, Zhang-Hua; Wang, Xi-Hua

    2014-11-01

    The spatially explicit model of leaf litter can help to understand its dispersal process, which is very important to predict the distribution pattern of leaves on the surface of the earth. In this paper, the spatially explicit model of leaf litter was developed for 20 tree species using litter trap data from the mapped forest plot in an evergreen broad-leaved forest in Tiantong, Zhejiang Pro- vince, eastern China. Applicability of the model was analyzed. The model assumed an allometric equation between diameter at breast height (DBH) and leaf litter amount, and the leaf litter declined exponentially with the distance. Model parameters were estimated by the maximum likelihood method. Results showed that the predicted and measured leaf litter amounts were significantly correlated, but the prediction accuracies varied widely for the different tree species, averaging at 49.3% and ranging from 16.0% and 74.0%. Model qualities of tree species significantly correlated with the standard deviations of the leaf litter amount per trap, DBH of the tree species and the average leaf dry mass of tree species. There were several ways to improve the forecast precision of the model, such as installing the litterfall traps according to the distribution of the tree to cover the different classes of the DBH and distance apart from the parent trees, determining the optimal dispersal function of each tree species, and optimizing the existing dispersal function. PMID:25898606

  12. Ultra-spatial synchrotron radiation for imaging molecular chemical structure: Applications in plant and animal studies

    DOE PAGESBeta

    Yu, Peiqiang

    2007-01-01

    Synchrotron-based Fourier transform infrared microspectroscopy (S-FTIR) has been developed as a rapid, direct, non-destructive, bioanalytical technique. This technique takes advantage of synchrotron light brightness and small effective source size and is capable of exploring the molecular chemical features and make-up within microstructures of a biological tissue without destruction of inherent structures at ultra-spatial resolutions within cellular dimension. To date there has been very little application of this advanced synchrotron technique to the study of plant and animal tissues' inherent structure at a cellular or subcellular level. In this article, a novel approach was introduced to show the potential of themore » newly developed, advanced synchrotron-based analytical technology, which can be used to reveal molecular structural-chemical features of various plant and animal tissues.« less

  13. Detection of spatially extended sources in high energy astrophysics with special application to lunar occultation

    NASA Astrophysics Data System (ADS)

    Jenke, Peter Alexander

    2009-01-01

    Occultation is a technique that enables image reconstruction and source identification with a non-imaging detector. Such an approach is well suited for a future survey mission in nuclear astrophysics. In particular, the Lunar Occultation Technique (LOT) utilizes the Moon as an occulting object and is the basis of a new gamma-ray survey mission concept, the Lunar OCcultation Observer (LOCO). Techniques utilizing the LOT to detect spatially extended emission, from the Galactic plane or Galactic Center region, have been developed. Given knowledge of detector position in lunar orbit, combined with lunar ephemeris and relevant coordinate transformations, occultation time series can be used to reconstruct skymaps of these extended Galactic emitters. Monte-Carlo Markov Chains (MCMC), incorporating the Metropolis-Hastings algorithm for parametric model testing, form the basis of the technique. Performance of the imaging methodology, and its application to nuclear astrophysics will be presented.

  14. A GIS-based approach for spatial analysis of agricultural nitrogen pollution and its application

    NASA Astrophysics Data System (ADS)

    Lu, Liping; Liu, Weidong; Sun, Lin; Qin, Zhihao

    2009-10-01

    Agricultural pollution, which has a direct impact on the water, soil and air quality, is a common but increasingly serious environmental problem nowadays. The misusage of fertilizer, high application fertilizer and low utilization rate, are the major factors of the pollution. Therefore, the pollution caused by nitrate nitrogen has posed a very serious problem to the ecological environment. Combined with the GIS technology, this paper takes Majiang County in Guizhou province that is at southwest of China as a case, to carry out the research on the calculation of the nitrogen surplus in paddy field and the dry land based on the farmland nutrient balance model using the fertilizer amount. This paper reveals the spatial distribution characteristic of the nitrogen pollution, which can help to find a reasonable crop cultivation and fertilization methods to increase the effective utilization fertilization and therefore reduce the pollution.

  15. Advanced Spatial-Division Multiplexed Measurement Systems Propositions-From Telecommunication to Sensing Applications: A Review.

    PubMed

    Weng, Yi; Ip, Ezra; Pan, Zhongqi; Wang, Ting

    2016-01-01

    The concepts of spatial-division multiplexing (SDM) technology were first proposed in the telecommunications industry as an indispensable solution to reduce the cost-per-bit of optical fiber transmission. Recently, such spatial channels and modes have been applied in optical sensing applications where the returned echo is analyzed for the collection of essential environmental information. The key advantages of implementing SDM techniques in optical measurement systems include the multi-parameter discriminative capability and accuracy improvement. In this paper, to help readers without a telecommunication background better understand how the SDM-based sensing systems can be incorporated, the crucial components of SDM techniques, such as laser beam shaping, mode generation and conversion, multimode or multicore elements using special fibers and multiplexers are introduced, along with the recent developments in SDM amplifiers, opto-electronic sources and detection units of sensing systems. The examples of SDM-based sensing systems not only include Brillouin optical time-domain reflectometry or Brillouin optical time-domain analysis (BOTDR/BOTDA) using few-mode fibers (FMF) and the multicore fiber (MCF) based integrated fiber Bragg grating (FBG) sensors, but also involve the widely used components with their whole information used in the full multimode constructions, such as the whispering gallery modes for fiber profiling and chemical species measurements, the screw/twisted modes for examining water quality, as well as the optical beam shaping to improve cantilever deflection measurements. Besides, the various applications of SDM sensors, the cost efficiency issue, as well as how these complex mode multiplexing techniques might improve the standard fiber-optic sensor approaches using single-mode fibers (SMF) and photonic crystal fibers (PCF) have also been summarized. Finally, we conclude with a prospective outlook for the opportunities and challenges of SDM

  16. Modeling diffusion-weighted MRI as a spatially variant Gaussian mixture: Application to image denoising

    PubMed Central

    Gonzalez, Juan Eugenio Iglesias; Thompson, Paul M.; Zhao, Aishan; Tu, Zhuowen

    2011-01-01

    Purpose: This work describes a spatially variant mixture model constrained by a Markov random field to model high angular resolution diffusion imaging (HARDI) data. Mixture models suit HARDI well because the attenuation by diffusion is inherently a mixture. The goal is to create a general model that can be used in different applications. This study focuses on image denoising and segmentation (primarily the former). Methods: HARDI signal attenuation data are used to train a Gaussian mixture model in which the mean vectors and covariance matrices are assumed to be independent of spatial locations, whereas the mixture weights are allowed to vary at different lattice positions. Spatial smoothness of the data is ensured by imposing a Markov random field prior on the mixture weights. The model is trained in an unsupervised fashion using the expectation maximization algorithm. The number of mixture components is determined using the minimum message length criterion from information theory. Once the model has been trained, it can be fitted to a noisy diffusion MRI volume by maximizing the posterior probability of the underlying noiseless data in a Bayesian framework, recovering a denoised version of the image. Moreover, the fitted probability maps of the mixture components can be used as features for posterior image segmentation. Results: The model-based denoising algorithm proposed here was compared on real data with three other approaches that are commonly used in the literature: Gaussian filtering, anisotropic diffusion, and Rician-adapted nonlocal means. The comparison shows that, at low signal-to-noise ratio, when these methods falter, our algorithm considerably outperforms them. When tractography is performed on the model-fitted data rather than on the noisy measurements, the quality of the output improves substantially. Finally, ventricle and caudate nucleus segmentation experiments also show the potential usefulness of the mixture probability maps for

  17. Making digital phantoms with spectral and spatial light modulators for quantitative applications of hyperspectral optical medical imaging devices

    NASA Astrophysics Data System (ADS)

    Chon, Bonghwan; Tokumasu, Fuyuki; Lee, Ji Youn; Allen, David W.; Rice, Joseph P.; Hwang, Jeeseong

    2015-03-01

    We present a procedure to generate digital phantoms with a hyperspectral image projector (HIP) consisting of two liquid crystal on silicon (LCoS) spatial light modulators (SLMs). The digital phantoms are 3D image data cubes of the spatial distribution of spectrally resolved abundances of intracellular light-absorbing oxy-hemoglobin molecules in single erythrocytes. Spectrally and spatially resolved image data indistinguishable from the real scene may be used as standards to calibrate image sensors and validate image analysis algorithms for their measurement quality, performance consistency, and inter-laboratory comparisons for quantitative biomedical imaging applications.

  18. Geodesic Information Flows: Spatially-Variant Graphs and Their Application to Segmentation and Fusion.

    PubMed

    Cardoso, M Jorge; Modat, Marc; Wolz, Robin; Melbourne, Andrew; Cash, David; Rueckert, Daniel; Ourselin, Sebastien

    2015-09-01

    Clinical annotations, such as voxel-wise binary or probabilistic tissue segmentations, structural parcellations, pathological regions-of-interest and anatomical landmarks are key to many clinical studies. However, due to the time consuming nature of manually generating these annotations, they tend to be scarce and limited to small subsets of data. This work explores a novel framework to propagate voxel-wise annotations between morphologically dissimilar images by diffusing and mapping the available examples through intermediate steps. A spatially-variant graph structure connecting morphologically similar subjects is introduced over a database of images, enabling the gradual diffusion of information to all the subjects, even in the presence of large-scale morphological variability. We illustrate the utility of the proposed framework on two example applications: brain parcellation using categorical labels and tissue segmentation using probabilistic features. The application of the proposed method to categorical label fusion showed highly statistically significant improvements when compared to state-of-the-art methodologies. Significant improvements were also observed when applying the proposed framework to probabilistic tissue segmentation of both synthetic and real data, mainly in the presence of large morphological variability. PMID:25879909

  19. A spatial application of a vegetation productivity equation for neo-soil reconstruction

    SciTech Connect

    Burley, J.B.

    1999-07-01

    Reclamation specialists are interested in the application of recently developed soil productivity equations for post-mining reclamation planning and design. This paper presents the application of one recently developed soil productivity equation to a surface coal mine site in Mercer County, North Dakota. Geographic information systems (GIS) technology (Map*Factory 1.1) was combined with a soil productivity equation developed by the author to generate a GIS script to calculate a site's pre-mining productivity per 10 meter grid cell and then summed to calculate the grand and the expected average soil productivity for the site, resulting in a pre-mining baseline numerical spatial scores. Several post-mining alternatives were evaluated to study various soil management strategies to restore post-mining soil productivity, including: an abandoned mine landscape treatment, a reconstructed topsoil treatment with graded gentile slopes, and a reconstructed topsoil treatment with soil improvements. The results indicated that the abandoned mine scenario was significantly different than the other three treatments (p{le}0.05), with the reconstructed topsoil treatment with soil amendments generating the greatest estimated productivity.

  20. Using Geo-Spatial Technologies for Field Applications in Higher Geography Education

    ERIC Educational Resources Information Center

    Karatepe, Akif

    2012-01-01

    Today's important geo-spatial technologies, GIS (Geographic Information Systems), GPS (Global Positioning Systems) and Google Earth have been widely used in geography education. Transferring spatially oriented data taken by GPS to the GIS and Google Earth has provided great benefits in terms of showing the usage of spatial technologies for field…

  1. EMCCD based luminescence imaging system for spatially resolved geo-chronometric and radiation dosimetric applications

    NASA Astrophysics Data System (ADS)

    Chauhan, N.; Adhyaru, P.; Vaghela, H.; Singhvi, A. K.

    2014-11-01

    We report the development of an Electron Multiplier Charge Coupled Device (EMCCD) based luminescence dating system. The system enables position sensitive measurements of luminescence for the estimation of spatially resolved distribution of equivalent dose for complex geological samples. The system includes: 1) a sample stimulation unit (with both thermal and optical stimulations), 2) an optics unit that comprises imaging optics and, 3) a data acquisition and processing unit. The system works in a LabVIEW environment with a graphical user interface (GUI). User specified stimulation protocols enable thermal and optical stimulation in any desired combination. The optics unit images the luminescence on to a EMCCD (512 × 512 pixels, each of 16μm × 16μm size) and maintains a unit magnification. This unit has flexible focusing and a filter housing that enables change of filters combinations without disturbing the setup. Time integrated EMCCD images of luminescence from the sample are acquired as a function of programmable dwell time and these images are processed using indigenously developed MATLAB based programs. Additionally, the programs align the acquired images using a set of control points (identifier features on the images) to a single pixel accuracy. The dose evaluation is based on integrated intensity from selected pixels followed by generation of a growth curve giving luminescence as a function of applied beta doses. Development of this EMCCD camera based luminescence system will enable in-situ luminescence measurements of the samples, without the requirement of separating mineral grains from their matrix. It will also allow age estimation of samples such as lithic artifacts/structures via dating of their surfaces, fusion crust of meteorites, pedogenic carbonates, etc and will additionally open up possibilities of application like testing spatial uniformity of doping in artificial luminescence phosphors, dating/dosimetry of inclusions etc.

  2. Spatial light modulators and applications III; Proceedings of the Meeting, San Diego, CA, Aug. 7, 8, 1989

    NASA Technical Reports Server (NTRS)

    Efron, Uzi (Editor)

    1990-01-01

    Recent advances in the technology and applications of spatial light modulators (SLMs) are discussed in review essays by leading experts. Topics addressed include materials for SLMs, SLM devices and device technology, applications to optical data processing, and applications to artificial neural networks. Particular attention is given to nonlinear optical polymers, liquid crystals, magnetooptic SLMs, multiple-quantum-well SLMs, deformable-mirror SLMs, three-dimensional optical memories, applications of photorefractive devices to optical computing, photonic neurocomputers and learning machines, holographic associative memories, SLMs as parallel memories for optoelectronic neural networks, and coherent-optics implementations of neural-network models.

  3. A spatially distributed energy balance snowmelt model for application in mountain basins

    USGS Publications Warehouse

    Marks, D.; Domingo, J.; Susong, D.; Link, T.; Garen, D.

    1999-01-01

    Snowmelt is the principal source for soil moisture, ground-water re-charge, and stream-flow in mountainous regions of the western US, Canada, and other similar regions of the world. Information on the timing, magnitude, and contributing area of melt under variable or changing climate conditions is required for successful water and resource management. A coupled energy and mass-balance model ISNOBAL is used to simulate the development and melting of the seasonal snowcover in several mountain basins in California, Idaho, and Utah. Simulations are done over basins varying from 1 to 2500 km2, with simulation periods varying from a few days for the smallest basin, Emerald Lake watershed in California, to multiple snow seasons for the Park City area in Utah. The model is driven by topographically corrected estimates of radiation, temperature, humidity, wind, and precipitation. Simulation results in all basins closely match independently measured snow water equivalent, snow depth, or runoff during both the development and depletion of the snowcover. Spatially distributed estimates of snow deposition and melt allow us to better understand the interaction between topographic structure, climate, and moisture availability in mountain basins of the western US. Application of topographically distributed models such as this will lead to improved water resource and watershed management.Snowmelt is the principal source for soil moisture, ground-water re-charge, and stream-flow in mountainous regions of the western US, Canada, and other similar regions of the world. Information on the timing, magnitude, and contributing area of melt under variable or changing climate conditions is required for successful water and resource management. A coupled energy and mass-balance model ISNOBAL is used to simulate the development and melting of the seasonal snowcover in several mountain basins in California, Idaho, and Utah. Simulations are done over basins varying from 1 to 2500 km2, with

  4. Application of Spatial Continuous Wavelet Transforms to Identify Noise in Regional Airborne Electromagnetic Data

    NASA Astrophysics Data System (ADS)

    Nenna, V.; Pidlisecky, A.

    2012-12-01

    As mapping of groundwater resources with airborne electromagnetics expands into more urban areas, it is increasingly important to identify sources of cultural noise in acquired data sets. A number of methods have been proposed to reduce the impact of cultural coupling on acquired data. While intense local calibration to increase the signal to noise ratio has been used, most often in practice, the transients associated with these noise sources are manually identified and filtered out during data processing. This can be a challenging task, particularly as datasets grow large (e.g. up to terabytes of data). In response to this, we propose a method for identifying noise in airborne electromagnetic data based on a spatial application of the continuous wavelet transform (CWT). We apply a continuous wavelet transform to three airborne electromagnetic surveys collected in the Edmonton-Calgary Corridor as part of a groundwater inventory sponsored by the Alberta Geological Survey and Environment Alberta. The three surveys consist of 210 flightlines covering approximately 18 000 linear kilometers with roughly 13 m sounding spacing. B-field and dB/dt data from a three-component 20-channel GeoTEM multicoil system, were recorded at 5 on-time and 15 off-time channels with a total measurement time of 16.664 ms per sounding. The nominal height of vertical axis transmitter was 120 m; the current pulse was 670 A, and the pulse-width was 4.045 ms. Wavelet transforms are localized in time and frequency, similar to a windowed Fourier transform, and are used to identify dominant frequencies within a signal as a function of time or space. While there are a number of options for wavelet functions, we convolve a Morlet wavelet with the data signal at 120 distance scales on a logarithmic scale from 0.1 to 30 km. We calculate the CWT along each flightline for all off-time channels. We then calculate the wavelet power normalized by the data variance, and bin results into 4 bins of spatial

  5. DOTAGWA: A CASE STUDY IN WEB-BASED ARCHITECTURES FOR CONNECTING SURFACE WATER MODELS TO SPATIALLY ENABLED WEB APPLICATIONS

    EPA Science Inventory

    The Automated Geospatial Watershed Assessment (AGWA) tool is a desktop application that uses widely available standardized spatial datasets to derive inputs for multi-scale hydrologic models (Miller et al., 2007). The required data sets include topography (DEM data), soils, clima...

  6. A spatially distributed energy balance snowmelt model for application in mountain basins

    NASA Astrophysics Data System (ADS)

    Marks, Danny; Domingo, James; Susong, Dave; Link, Tim; Garen, David

    1999-09-01

    Snowmelt is the principal source for soil moisture, ground-water re-charge, and stream-flow in mountainous regions of the western US, Canada, and other similar regions of the world. Information on the timing, magnitude, and contributing area of melt under variable or changing climate conditions is required for successful water and resource management. A coupled energy and mass-balance model ISNOBAL is used to simulate the development and melting of the seasonal snowcover in several mountain basins in California, Idaho, and Utah. Simulations are done over basins varying from 1 to 2500 km2, with simulation periods varying from a few days for the smallest basin, Emerald Lake watershed in California, to multiple snow seasons for the Park City area in Utah. The model is driven by topographically corrected estimates of radiation, temperature, humidity, wind, and precipitation. Simulation results in all basins closely match independently measured snow water equivalent, snow depth, or runoff during both the development and depletion of the snowcover. Spatially distributed estimates of snow deposition and melt allow us to better understand the interaction between topographic structure, climate, and moisture availability in mountain basins of the western US. Application of topographically distributed models such as this will lead to improved water resource and watershed management.

  7. Lighting up the World The first global application of the open source, spatial electrification toolkit (ONSSET)

    NASA Astrophysics Data System (ADS)

    Mentis, Dimitrios; Howells, Mark; Rogner, Holger; Korkovelos, Alexandros; Siyal, Shahid; Broad, Oliver; Zepeda, Eduardo; Bazilian, Morgan

    2016-04-01

    In September 2015, the international community has adopted a new set of targets, following and expanding on the millennium development goals (MDGs), the Sustainable Development Goals (SDGs). Ensuring access to affordable, reliable, sustainable and modern energy for all is one of the 17 set goals that each country should work towards realizing. According to the latest Global Tracking Framework, 15% of the global population live without access to electricity. The majority of those (87%) reside in rural areas. Countries can reach universal access through various electrification options, depending on different levels of energy intensity and local characteristics of the studied areas, such as renewable resources availability, spatially differentiated costs of diesel-fuelled electricity generation, distance from power network and major cities, population density and others, data which are usually inadequate in national databases. This general paucity of reliable energy-related information in developing countries calls for the utilization of geospatial data. This paper presents a Geographic Information Systems (GIS) based electrification analysis for all countries that have not yet reached full access to electricity (Sub-Saharan Africa, Developing Asia, Latin America and Middle East). The cost optimal mix of electrification options ranges from grid extensions to mini-grid and stand-alone applications and is identified for all relevant countries. It is illustrated how this mix is influenced by scrolling through various electrification levels and different oil prices. Such an analysis helps direct donors and investors and inform multinational actions with regards to investments related to energy access.

  8. Invariant Feature Matching for Image Registration Application Based on New Dissimilarity of Spatial Features

    PubMed Central

    Mousavi Kahaki, Seyed Mostafa; Nordin, Md Jan; Ashtari, Amir H.; J. Zahra, Sophia

    2016-01-01

    An invariant feature matching method is proposed as a spatially invariant feature matching approach. Deformation effects, such as affine and homography, change the local information within the image and can result in ambiguous local information pertaining to image points. New method based on dissimilarity values, which measures the dissimilarity of the features through the path based on Eigenvector properties, is proposed. Evidence shows that existing matching techniques using similarity metrics—such as normalized cross-correlation, squared sum of intensity differences and correlation coefficient—are insufficient for achieving adequate results under different image deformations. Thus, new descriptor’s similarity metrics based on normalized Eigenvector correlation and signal directional differences, which are robust under local variation of the image information, are proposed to establish an efficient feature matching technique. The method proposed in this study measures the dissimilarity in the signal frequency along the path between two features. Moreover, these dissimilarity values are accumulated in a 2D dissimilarity space, allowing accurate corresponding features to be extracted based on the cumulative space using a voting strategy. This method can be used in image registration applications, as it overcomes the limitations of the existing approaches. The output results demonstrate that the proposed technique outperforms the other methods when evaluated using a standard dataset, in terms of precision-recall and corner correspondence. PMID:26985996

  9. An electrostatic spatial resonance model for coaxial helical structures with applications to the filamentous bacteriophages.

    PubMed Central

    Marzec, C J; Day, L A

    1994-01-01

    A model is presented that treats the symmetry matching problem in structures made of two interacting coaxial helices of point charges. The charges are sources of a potential field that mediates a non-specific attractive interaction between the helices. The problem is represented in Fourier space, which affords the most generality. It is found that coaxial helices with optimally mated symmetries can lock into spatial resonance configurations that maximize their interaction. The resonances are represented as vectors in a discrete three-dimensional space. Two algebraic relations are given for the four symmetry parameters of two helices in resonance. One-start inner helices interacting with coaxial one-start or NR-start outer helices are considered. Applications are made to the filamentous bacteriophages Ff, Pf1, Xf, and Pf3. The interaction given by the linearized Poisson-Boltzmann equation is calculated in this formalism to allow comparison of the electrostatic free energy of interaction of different resonance structures. Experimental nucleotide/subunit ratios are accounted for, and models for the DNA-protein interfaces are presented, with particular emphasis on Pf1. PMID:7696463

  10. Design and Development of an Open Source Software Application for the Characterization of Spatially Variable Fields

    NASA Astrophysics Data System (ADS)

    Gunnell, D. K.; Osorio-Murillo, C. A.; Over, M. W.; Frystacky, H.; Ames, D. P.; Rubin, Y.

    2013-12-01

    The characterization of the structural parameters of spatially variable fields (SVFs) is essential to understanding the variability of hydrological processes such as infiltration, evapotranspiration, groundwater contaminant transport, etc. SVFs can be characterized using a Bayesian inverse method called Method of Anchored Distributions (MAD). This method characterizes the structural parameters of SVFs using prior information of structural parameter fields, indirect measurements, and simulation models allowing the transfer of valuable information to a target variable field. An example SVF in hydrology is hydraulic conductivity, which may be characterized by head pressure measurements through a simulation model such as MODFLOW. This poster will present the design and development of a free and open source inverse modeling desktop software application and extension framework called MAD# for the characterization of the structural parameters of SVFs using MAD. The developed software is designed with a flexible architecture to support different simulation models and random field generators and includes geographic information system (GIS) interfaces for representing, analyzing, and understanding SVFs. This framework has also been made compatible with Mono, a cross-platform implementation of C#, for a wider usability.

  11. On the spatial coherence in mixed sound fields and its application to signal-to-diffuse ratio estimation.

    PubMed

    Thiergart, Oliver; Del Galdo, Giovanni; Habets, Emanuël A P

    2012-10-01

    Many applications in spatial sound recording and processing model the sound scene as a sum of directional and diffuse sound components. The power ratio between both components, i.e., the signal-to-diffuse ratio (SDR), represents an important measure for algorithms which aim at performing robustly in reverberant environments. This contribution discusses the SDR estimation from the spatial coherence between two arbitrary first-order directional microphones. First, the spatial coherence is expressed as function of the SDR. For most microphone setups, the spatial coherence is a complex function where both the absolute value and phase contain relevant information on the SDR. Secondly, the SDR estimator is derived from the spatial coherence function. The estimator is discussed for different practical microphone setups including coincident setups of arbitrary first-order directional microphones and spaced setups of identical first-order directional microphones. An unbiased SDR estimation requires noiseless coherence estimates as well as information on the direction-of-arrival of the directional sound, which usually has to be estimated. Nevertheless, measurement results verify that the proposed estimator is applicable in practice and provides accurate results. PMID:23039430

  12. Spatial Double Generalized Beta Regression Models: Extensions and Application to Study Quality of Education in Colombia

    ERIC Educational Resources Information Center

    Cepeda-Cuervo, Edilberto; Núñez-Antón, Vicente

    2013-01-01

    In this article, a proposed Bayesian extension of the generalized beta spatial regression models is applied to the analysis of the quality of education in Colombia. We briefly revise the beta distribution and describe the joint modeling approach for the mean and dispersion parameters in the spatial regression models' setting. Finally, we…

  13. Measuring the value of air quality: application of the spatial hedonic model.

    PubMed

    Kim, Seung Gyu; Cho, Seong-Hoon; Lambert, Dayton M; Roberts, Roland K

    2010-03-01

    This study applies a hedonic model to assess the economic benefits of air quality improvement following the 1990 Clean Air Act Amendment at the county level in the lower 48 United States. An instrumental variable approach that combines geographically weighted regression and spatial autoregression methods (GWR-SEM) is adopted to simultaneously account for spatial heterogeneity and spatial autocorrelation. SEM mitigates spatial dependency while GWR addresses spatial heterogeneity by allowing response coefficients to vary across observations. Positive amenity values of improved air quality are found in four major clusters: (1) in East Kentucky and most of Georgia around the Southern Appalachian area; (2) in a few counties in Illinois; (3) on the border of Oklahoma and Kansas, on the border of Kansas and Nebraska, and in east Texas; and (4) in a few counties in Montana. Clusters of significant positive amenity values may exist because of a combination of intense air pollution and consumer awareness of diminishing air quality. PMID:20376167

  14. A spatial bivariate probit model for correlated binary data with application to adverse birth outcomes.

    PubMed

    Neelon, Brian; Anthopolos, Rebecca; Miranda, Marie Lynn

    2014-04-01

    Motivated by a study examining geographic variation in birth outcomes, we develop a spatial bivariate probit model for the joint analysis of preterm birth and low birth weight. The model uses a hierarchical structure to incorporate individual and areal-level information, as well as spatially dependent random effects for each spatial unit. Because rates of preterm birth and low birth weight are likely to be correlated within geographic regions, we model the spatial random effects via a bivariate conditionally autoregressive prior, which induces regional dependence between the outcomes and provides spatial smoothing and sharing of information across neighboring areas. Under this general framework, one can obtain region-specific joint, conditional, and marginal inferences of interest. We adopt a Bayesian modeling approach and develop a practical Markov chain Monte Carlo computational algorithm that relies primarily on easily sampled Gibbs steps. We illustrate the model using data from the 2007-2008 North Carolina Detailed Birth Record. PMID:22599322

  15. Expanding Scales and Applications for 2D Spatial Mapping of CO2 using GreenLITE

    NASA Astrophysics Data System (ADS)

    Erxleben, W. H.; Dobler, J. T.; Zaccheo, T. S.; Blume, N.; Braun, M.

    2015-12-01

    The Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE) system is a new measurement approach originally developed under a cooperative agreement with the Department of Energy (DOE) National Energy Technology Laboratory (NETL), Atmospheric Environmental Sciences (AER) and Exelis Inc. (now part of Harris Corp.). The original system design provides 24/7 monitoring of Ground Carbon Storage (GCS) sites, in order to help ensure worker safety and verify 99% containment. The first generation was designed to cover up to 1km2 area, and employs the Exelis Continuous Wave (CW) Intensity Modulated (IM) approach to measure differential transmission. A pair of scanning transceivers was built and combined with a series of retro reflectors, and a local weather station to provide the information required for producing estimates of the atmospheric CO2 concentration over a number of overlapping lines-of-site. The information from the transceivers, and weather station, are sent remotely to a web-based processing and storage tool, which in-turn uses the data to generate estimates of the 2D spatial distribution over the area of coverage and disseminate that information near real-time via a secure web interface. Recently, in 2015, Exelis and AER have invested in the expansion of the GreenLITE transceiver system to 5 km range, enabling areas up to 25 km2 to be evaluated with this technology, and opening new possibilities for applications such as urban scale monitoring. The 5 km system is being tested in conjunction with the National Institute of Standards and Technology at the Boulder Atmospheric Observatory in August of this year. This talk will review the initial GreenLITE system, testing and deployment of that system, and the more recent development, expansion and testing of the 5 km system.

  16. Application of spatial features to satellite land-use analysis. [spectral signature variations

    NASA Technical Reports Server (NTRS)

    Smith, J.; Hornung, R.; Berry, J.

    1975-01-01

    A Level I land-use analysis of selected training areas of the Colorado Front Range was carried out using digital ERTS-A satellite imagery. Level I land-use categories included urban, agriculture (irrigated and dryland farming), rangeland, and forests. The spatial variations in spectral response for these land-use classes were analyzed using discrete two-dimensional Fourier transforms to isolate and extract spatial features. Analysis was performed on ERTS frame 1352-17134 (July 10, 1973) and frame number 1388-17131 (August 15, 1973). On training sets, spatial features yielded 80 to 100 percent classification accuracies with commission errors ranging from 0 to 20 percent.

  17. Application of spatial Poisson process models to air mass thunderstorm rainfall

    NASA Technical Reports Server (NTRS)

    Eagleson, P. S.; Fennessy, N. M.; Wang, Qinliang; Rodriguez-Iturbe, I.

    1987-01-01

    Eight years of summer storm rainfall observations from 93 stations in and around the 154 sq km Walnut Gulch catchment of the Agricultural Research Service, U.S. Department of Agriculture, in Arizona are processed to yield the total station depths of 428 storms. Statistical analysis of these random fields yields the first two moments, the spatial correlation and variance functions, and the spatial distribution of total rainfall for each storm. The absolute and relative worth of three Poisson models are evaluated by comparing their prediction of the spatial distribution of storm rainfall with observations from the second half of the sample. The effect of interstorm parameter variation is examined.

  18. A SPATIALLY EXPLICIT HIERARCHICAL APPROACH TO MODELING COMPLEX ECOLOGICAL SYSTEMS: THEORY AND APPLICATIONS. (R827676)

    EPA Science Inventory

    Ecological systems are generally considered among the most complex because they are characterized by a large number of diverse components, nonlinear interactions, scale multiplicity, and spatial heterogeneity. Hierarchy theory, as well as empirical evidence, suggests that comp...

  19. Application of spatially weighted Technology for mapping intermediate and felsic igneous rocks in Fujian Province, China

    NASA Astrophysics Data System (ADS)

    Zhang, Daojun

    2016-04-01

    Magmatic activity is of great significance to mineralization not only for heat and fluid it provides, but also for parts of material source it brings. Due to the cover of soil and vegetation and its spatial nonuniformity detected singals from the ground's surface may be weak and of spatial variability, and this brings serious challenges to mineral exploration in these areas. Two models based on spatially weighted technology, i.e., local singularity analysis (LSA) and spatially weighted logistic regression (SWLR) are applied in this study to deal with this challenge. Coverage cannot block the migration of geochemical elements, it is possible that the geochemical features of soil above concealed rocks can be different from surrounding environment, although this kind of differences are weak; coverage may also weaken the surface expression of geophysical fields. LSA is sensitive to weak changes in density or energy, which makes it effective to map the distribution of concealed igneous rock based on geochemical and geophysical properties. Data integration can produce better classification results than any single data analysis, but spatial variability of spatial variables caused by non-stationary coverage can greatly affect the results since sometimes it is hard to establish a global model. In this paper, SWLR is used to integrate all spatial layers extracted from both geochemical and geophysical data, and the iron polymetallic metallogenic belt in sours-west of Fujian Province is used as s study case. It is found that LSA technique effectively extracts different sources of geologic anomalies; and the spatial distribution of intermediate and felsic igneous rocks delineated by SWLR shows higher accuracy compared with the result obtained via global model.

  20. Spatial pattern of 2009 dengue distribution in Kuala Lumpur using GIS application.

    PubMed

    Aziz, S; Ngui, R; Lim, Y A L; Sholehah, I; Nur Farhana, J; Azizan, A S; Wan Yusoff, W S

    2012-03-01

    In the last few years in Malaysia, dengue fever has increased dramatically and has caused huge public health concerns. The present study aimed to establish a spatial distribution of dengue cases in the city of Kuala Lumpur using a combination of Geographic Information System (GIS) and spatial statistical tools. Collation of data from 1,618 dengue cases in 2009 was obtained from Kuala Lumpur City Hall (DBKL). These data were processed and then converted into GIS format. Information on the average monthly rainfall was also used to correlate with the distribution pattern of dengue cases. To asses the spatial distribution of dengue cases, Average Nearest Neighbor (ANN) Analysis was applied together with spatial analysis with the ESRI ArcGIS V9.3 programme. Results indicated that the distribution of dengue cases in Kuala Lumpur for the year 2009 was spatially clustered with R value less than 1 (R = 0.42; z-scores = - 4.47; p < 0.001). Nevertheless, when this pattern was further analyzed according to month by each zone within Kuala Lumpur, two distinct patterns were observed which include a clustered pattern (R value < 1) between April to June and a dispersed pattern (R value > 1) between August and November. In addition, the mean monthly rainfall has not influenced the distribution pattern of the dengue cases. Implementation of control measures is more difficult for dispersed pattern compared to clustered pattern. From this study, it was found that distribution pattern of dengue cases in Kuala Lumpur in 2009 was spatially distributed (dispersed or clustered) rather than cases occurring randomly. It was proven that by using GIS and spatial statistic tools, we can determine the spatial distribution between dengue and population. Utilization of GIS tools is vital in assisting health agencies, epidemiologist, public health officer, town planner and relevant authorities in developing efficient control measures and contingency programmes to effectively combat dengue fever

  1. GWR-PM - Spatial variation relationship analysis with Geographically Weighted Regression (GWR) - An application at Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Jamhuri, J.; Azhar, B. M. S.; Puan, C. L.; Norizah, K.

    2016-06-01

    GWR-PM has been developed exclusively for decision makers in Peninsular Malaysia and the purpose is to provide them with additional flexibility in analysing spatial variation. While GWR extension analysis in ArcMap application has a universal coordinate system, GWR-PM is specifically designed with Peninsular Malaysia's coordinate system of Kertau RSO Malaya Meter. This paper presents the development of GWR-PM model by using a model builder, the application of which is to examine the forest fire risk at North Selangor Peat Swamp Forest. This model can be extended and improved by using ArcGIS language of phyton.

  2. Multilevel Modelling with Spatial Interaction Effects with Application to an Emerging Land Market in Beijing, China

    PubMed Central

    Dong, Guanpeng; Harris, Richard; Jones, Kelvyn; Yu, Jianhui

    2015-01-01

    This paper develops a methodology for extending multilevel modelling to incorporate spatial interaction effects. The motivation is that classic multilevel models are not specifically spatial. Lower level units may be nested into higher level ones based on a geographical hierarchy (or a membership structure—for example, census zones into regions) but the actual locations of the units and the distances between them are not directly considered: what matters is the groupings but not how close together any two units are within those groupings. As a consequence, spatial interaction effects are neither modelled nor measured, confounding group effects (understood as some sort of contextual effect that acts ‘top down’ upon members of a group) with proximity effects (some sort of joint dependency that emerges between neighbours). To deal with this, we incorporate spatial simultaneous autoregressive processes into both the outcome variable and the higher level residuals. To assess the performance of the proposed method and the classic multilevel model, a series of Monte Carlo simulations are conducted. The results show that the proposed method performs well in retrieving the true model parameters whereas the classic multilevel model provides biased and inefficient parameter estimation in the presence of spatial interactions. An important implication of the study is to be cautious of an apparent neighbourhood effect in terms of both its magnitude and statistical significance if spatial interaction effects at a lower level are suspected. Applying the new approach to a two-level land price data set for Beijing, China, we find significant spatial interactions at both the land parcel and district levels. PMID:26086913

  3. Monitoring survival rates of landbirds at varying spatial scales: An application of the MAPS Program

    USGS Publications Warehouse

    Rosenberg, D.K.; DeSante, D.F.; Hines, J.E.

    2000-01-01

    Survivorship is a primary demographic parameter affecting population dynamics, and thus trends in species abundance. The Monitoring Avian Productivity and Survivorship (MAPS) program is a cooperative effort designed to monitor landbird demographic parameters. A principle goal of MAPS is to estimate annual survivorship and identify spatial patterns and temporal trends in these rates. We evaluated hypotheses of spatial patterns in survival rates among a collection of neighboring sampling sites, such as within national forests, among biogeographic provinces, and between breeding populations that winter in either Central or South America, and compared these geographic-specific models to a model of a common survival rate among all sampling sites. We used data collected during 1992-1995 from Swainson's Thrush (Cathorus ustulatus) populations in the western region of the United States. We evaluated the ability to detect spatial and temporal patterns of survivorship with simulated data. We found weak evidence of spatial differences in survival rates at the local scale of 'location,' which typically contained 3 mist-netting stations. There was little evidence of differences in survival rates among biogeographic provinces or between populations that winter in either Central or South America. When data were pooled for a regional estimate of survivorship, the percent relative bias due to pooling 'locations' was 12 years of monitoring. Detection of spatial patterns and temporal trends in survival rates from local to regional scales will provide important information for management and future research directed toward conservation of landbirds.

  4. 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.

  5. A Key Concept: Spatial Organization

    ERIC Educational Resources Information Center

    Kostrowicki, Jerzy

    1975-01-01

    The application of geography to spatial planning is discussed. Concepts presented include the regional concept, the typological concept, and spatial structure, spatial processes, and spatial organization. For address of journal see SO 504 028. (Author/RM)

  6. Unsupervised Spatial Event Detection in Targeted Domains with Applications to Civil Unrest Modeling

    PubMed Central

    Zhao, Liang; Chen, Feng; Dai, Jing; Hua, Ting; Lu, Chang-Tien; Ramakrishnan, Naren

    2014-01-01

    Twitter has become a popular data source as a surrogate for monitoring and detecting events. Targeted domains such as crime, election, and social unrest require the creation of algorithms capable of detecting events pertinent to these domains. Due to the unstructured language, short-length messages, dynamics, and heterogeneity typical of Twitter data streams, it is technically difficult and labor-intensive to develop and maintain supervised learning systems. We present a novel unsupervised approach for detecting spatial events in targeted domains and illustrate this approach using one specific domain, viz. civil unrest modeling. Given a targeted domain, we propose a dynamic query expansion algorithm to iteratively expand domain-related terms, and generate a tweet homogeneous graph. An anomaly identification method is utilized to detect spatial events over this graph by jointly maximizing local modularity and spatial scan statistics. Extensive experiments conducted in 10 Latin American countries demonstrate the effectiveness of the proposed approach. PMID:25350136

  7. Application of spatially distributed water and carbon flux models over the Columbia River Basin

    SciTech Connect

    Marks, D.; Turner, D.P.

    1995-06-01

    A georeferenced database at the 1 km spatial resolution was developed to initialize and drive process-based models of water and carbon flux over the Columbia River Basin (671,579 km{sup 2}). Estimates were made at each grid cell for variables including daily solar radiation, air temperature, humidity, and precipitation as climate drivers, and topographic structure, water holding capacity, vegetation type and leaf area as physical conditions. The database has been used to compare alternative algorithms for modeling evapotranspiration, carbon flux, and snow melt at the regional scale. It also provided a means to perform scaling exercises which examine the effects of spatial aggregation on model inputs and outputs. Relatively high spatial resolution analysis of biogeochemical cycling are desirable from several perspectives and may be particularly important in the study of the potential impacts of climate change.

  8. 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

  9. Spatial quantile regression using INLA with applications to childhood overweight in Malawi.

    PubMed

    Mtambo, Owen P L; Masangwi, Salule J; Kazembe, Lawrence N M

    2015-04-01

    Analyses of childhood overweight have mainly used mean regression. However, using quantile regression is more appropriate as it provides flexibility to analyse the determinants of overweight corresponding to quantiles of interest. The main objective of this study was to fit a Bayesian additive quantile regression model with structured spatial effects for childhood overweight in Malawi using the 2010 Malawi DHS data. Inference was fully Bayesian using R-INLA package. The significant determinants of childhood overweight ranged from socio-demographic factors such as type of residence to child and maternal factors such as child age and maternal BMI. We observed significant positive structured spatial effects on childhood overweight in some districts of Malawi. We recommended that the childhood malnutrition policy makers should consider timely interventions based on risk factors as identified in this paper including spatial targets of interventions. PMID:26046633

  10. Application of adaptive optics in complicated and integrated spatial multisensor system and its measurement analysis

    NASA Astrophysics Data System (ADS)

    Ding, Quanxin; Guo, Chunjie; Cai, Meng; Liu, Hua

    2007-12-01

    Adaptive Optics Expand System is a kind of new concept spatial equipment, which concerns system, cybernetics and informatics deeply, and is key way to improve advanced sensors ability. Traditional Zernike Phase Contrast Method is developed, and Accelerated High-level Phase Contrast Theory is established. Integration theory and mathematical simulation is achieved. Such Equipment, which is based on some crucial components, such as, core optical system, multi mode wavefront sensor and so on, is established for AOES advantageous configuration and global design. Studies on Complicated Spatial Multisensor System Integratation and measurement Analysis including error analysis are carried out.

  11. A multi-equation spatial econometric model, with application to EU manufacturing productivity growth

    NASA Astrophysics Data System (ADS)

    Fingleton, Bernard

    2007-06-01

    A multi-equation spatial econometric model is used to explain variations across EU regions in manufacturing productivity growth based on recent theoretical developments in urban economics and economic geography. The paper shows that temporal and spatial parameter homogeneity is an unrealistic assumption, contrary to what is typically assumed in the literature. Constraints are imposed on parameters across time periods and between core and peripheral regions of the EU, with the significant loss of fit providing overwhelming evidence of parameter heterogeneity, although the final model does highlight increasing returns to scale, which is a central feature of contemporary theory.

  12. Application of spatially referenced regression modeling for the evaluation of total nitrogen loading in the Chesapeake Bay watershed

    USGS Publications Warehouse

    Preston, Stephen D.; Brakebill, John W.

    1999-01-01

    The reduction of stream nutrient loads is an important part of current efforts to improve water quality in the Chesapeake Bay. To design programs that will effectively reduce stream nutrient loading, resource managers need spatially detailed information that describes the location of nutrient sources and the watershed factors that affect delivery of nutrients to the Bay. To address this need, the U.S. Geological Survey has developed a set of spatially referenced regression models for the evaluation of nutrient loading in the watershed. The technique applied for this purpose is referred to as ?SPARROW? (SPAtially Referenced Regressions On Watershed attributes), which is a statistical modeling approach that retains spatial referencing for illustrating predictions, and for relating upstream nutrient sources to downstream nutrient loads. SPARROW is based on a digital stream-network data set that is composed of stream segments (reaches) that are attributed with traveltime and connectivity information. Drainage-basin boundaries are defined for each stream reach in the network data set through the use of a digital elevation model. For the Chesapeake Bay watershed, the spatial network was developed using the U.S. Environmental Protection Agency?s River Reach File 1 digital stream network, and is composed of 1,408 stream reaches and watershed segments. To develop a SPARROW model for total nitrogen in the Chesapeake Bay watershed, data sets for sources and basin characteristics were incorporated into the spatial network and related to stream-loading information by using a nonlinear regression model approach. Total nitrogen source variables that were statistically significant in the model include point sources, urban area, fertilizer application, manure generation and atmospheric deposition. Total nitrogen loss variables that were significant in the model include soil permeability and instream-loss rates for four stream-reach classes. Applications of SPARROW for evaluating

  13. 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

  14. Integration of high-resolution spatial and spectral data acquisition systems to provide complementary datasets for cultural heritage applications

    NASA Astrophysics Data System (ADS)

    Simon, Camille; Huxhagen, Uwe; Mansouri, Alamin; Heritage, Adrian; Boochs, Frank; Marzani, Franck S.

    2010-02-01

    Modern optical measuring systems are able to record objects with high spatial and spectral precision. The acquisition of spatial data is possible with resolutions of a few hundredths of a millimeter using active projection-based camera systems, while spectral data can be obtained using filter-based multispectral camera systems that can capture surface spectral reflectance with high spatial resolution. We present a methodology for combining data from these two discrete optical measuring systems by registering their individual measurements into a common geometrical frame. Furthermore, the potential for its application as a tool for the non-invasive monitoring of paintings and polychromy is evaluated. The integration of time-referenced spatial and spectral datasets is beneficial to record and monitor cultural heritage. This enables the type and extent of surface and colorimetric change to be precisely characterized and quantified over time. Together, these could facilitate the study of deterioration mechanisms or the efficacy of conservation treatments by measuring the rate, type, and amount of change over time. An interdisciplinary team of imaging scientists and art scholars was assembled to undertake a trial program of repeated data acquisitions of several valuable historic surfaces of cultural heritage objects. The preliminary results are presented and discussed.

  15. SPHARA - A Generalized Spatial Fourier Analysis for Multi-Sensor Systems with Non-Uniformly Arranged Sensors: Application to EEG

    PubMed Central

    Graichen, Uwe; Eichardt, Roland; Fiedler, Patrique; Strohmeier, Daniel; Zanow, Frank; Haueisen, Jens

    2015-01-01

    Important requirements for the analysis of multichannel EEG data are efficient techniques for signal enhancement, signal decomposition, feature extraction, and dimensionality reduction. We propose a new approach for spatial harmonic analysis (SPHARA) that extends the classical spatial Fourier analysis to EEG sensors positioned non-uniformly on the surface of the head. The proposed method is based on the eigenanalysis of the discrete Laplace-Beltrami operator defined on a triangular mesh. We present several ways to discretize the continuous Laplace-Beltrami operator and compare the properties of the resulting basis functions computed using these discretization methods. We apply SPHARA to somatosensory evoked potential data from eleven volunteers and demonstrate the ability of the method for spatial data decomposition, dimensionality reduction and noise suppression. When employing SPHARA for dimensionality reduction, a significantly more compact representation can be achieved using the FEM approach, compared to the other discretization methods. Using FEM, to recover 95% and 99% of the total energy of the EEG data, on average only 35% and 58% of the coefficients are necessary. The capability of SPHARA for noise suppression is shown using artificial data. We conclude that SPHARA can be used for spatial harmonic analysis of multi-sensor data at arbitrary positions and can be utilized in a variety of other applications. PMID:25885290

  16. Application of spatial pedotransfer functions to understand soil modulation of vegetation response to climate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A fundamental knowledge gap in understanding land-atmosphere interactions is accurate, high resolution spatial representation of soil physical and hydraulic properties. We present a novel approach to predict hydraulic soil parameters by combining digital soil mapping techniques with pedotransfer fun...

  17. Digital Hydrologic Networks Supporting Applications Related to Spatially Referenced Regression Modeling1

    PubMed Central

    Brakebill, JW; Wolock, DM; Terziotti, SE

    2011-01-01

    Abstract Digital hydrologic networks depicting surface-water pathways and their associated drainage catchments provide a key component to hydrologic analysis and modeling. Collectively, they form common spatial units that can be used to frame the descriptions of aquatic and watershed processes. In addition, they provide the ability to simulate and route the movement of water and associated constituents throughout the landscape. Digital hydrologic networks have evolved from derivatives of mapping products to detailed, interconnected, spatially referenced networks of water pathways, drainage areas, and stream and watershed characteristics. These properties are important because they enhance the ability to spatially evaluate factors that affect the sources and transport of water-quality constituents at various scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW), a process-based/statistical model, relies on a digital hydrologic network in order to establish relations between quantities of monitored contaminant flux, contaminant sources, and the associated physical characteristics affecting contaminant transport. Digital hydrologic networks modified from the River Reach File (RF1) and National Hydrography Dataset (NHD) geospatial datasets provided frameworks for SPARROW in six regions of the conterminous United States. In addition, characteristics of the modified RF1 were used to update estimates of mean-annual streamflow. This produced more current flow estimates for use in SPARROW modeling. PMID:22457575

  18. Dynamic spatially-explicit mass-balance modeling for targeted watershed phosphorus management II: Model Application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cost-effective nonpoint source phosphorus (P) control should target the land areas at greatest risk for P loss. We combined mass-balance modeling and geographic analysis to identify and map high-risk areas for P export by integrating long-term P input/output accounting with spatially variable physi...

  19. Digital Hydrologic Networks Supporting Applications Related to Spatially Referenced Regression Modeling.

    PubMed

    Brakebill, Jw; Wolock, Dm; Terziotti, Se

    2011-10-01

    Digital hydrologic networks depicting surface-water pathways and their associated drainage catchments provide a key component to hydrologic analysis and modeling. Collectively, they form common spatial units that can be used to frame the descriptions of aquatic and watershed processes. In addition, they provide the ability to simulate and route the movement of water and associated constituents throughout the landscape. Digital hydrologic networks have evolved from derivatives of mapping products to detailed, interconnected, spatially referenced networks of water pathways, drainage areas, and stream and watershed characteristics. These properties are important because they enhance the ability to spatially evaluate factors that affect the sources and transport of water-quality constituents at various scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW), a process-based/statistical model, relies on a digital hydrologic network in order to establish relations between quantities of monitored contaminant flux, contaminant sources, and the associated physical characteristics affecting contaminant transport. Digital hydrologic networks modified from the River Reach File (RF1) and National Hydrography Dataset (NHD) geospatial datasets provided frameworks for SPARROW in six regions of the conterminous United States. In addition, characteristics of the modified RF1 were used to update estimates of mean-annual streamflow. This produced more current flow estimates for use in SPARROW modeling. PMID:22457575

  20. Estimation and Application of Spatially Variable Noise Fields in Diffusion Tensor Imaging

    PubMed Central

    Landman, Bennett A.; Bazin, Pierre-Louis; Prince, Jerry L.

    2009-01-01

    Optimal interpretation of magnetic resonance image content often requires an estimate of the underlying image noise, which is typically realized as a spatially invariant estimate of the noise distribution. This is not an ideal practice in diffusion tensor imaging because the noise distribution is usually spatially varying due to the use of fast imaging and noise suppression techniques. A new estimation approach for spatially varying noise fields is proposed in this article. The approach is based on a noise invariance property in scenarios in which more than one image, each with potentially different signal levels, are acquired on each slice, as in diffusion weighted MRI. This technique leads to improved noise field estimates in simulations, phantom experiments and in vivo studies when compared to traditional noise field estimators that use regional variability or background intensity histograms. The proposed method reduces the noise field estimation error by a factor of 100 in simulations, shows a strong linear correlation (R2 = 0.99) between theoretical and estimated noise changes in phantoms, and demonstrates consistent (<5% variability) noise field estimates in vivo. The advantages of spatially varying noise field estimation are demonstrated for power analysis, outlier detection, and tensor estimation. PMID:19250784

  1. Application of spatial cross correlation to detection of migration of submarine sand dunes

    NASA Astrophysics Data System (ADS)

    Duffy, Garret P.; Hughes-Clarke, John E.

    2005-12-01

    Knowledge of migration rates of bedforms provides an indirect indication of the behavior of tidally averaged bottom currents, enables optimization of hydrographic survey frequency and may enable calculation of bedload transport rate. To measure bedform migration rate, we test the use of spatial correlation as a measurement method, which quantifies and locates a region of maximum similarity between two spatial variables. For the latter, we use consecutive eight-bit images of spatial gradient, derived from bathymetric digital terrain models, carrying out the correlation over this representation of the shape of the seabed rather than the bathymetric surface. The digital terrain models were compiled from six repeat multibeam surveys of a headland-associated bank near Saint John, New Brunswick, with a roughly 30-day interval. Vectors are drawn depicting the movement of a sand dune at time t0 toward a point in the spatial correlation array at a later time, t1. A number of different techniques of picking the end of the migration vector were used. The sinuosity of the dune crest at the scale of the correlation window has an impact on which migration vector is the better pick. Averaging of migration vectors from consecutive epochs diminishes random errors in the correlation picks using any single pair of images and creates a more accurate picture of the migration field. Migration rates and crest-relative migration directions vary substantially across the sand bank, reflecting the high gradients in bottom shear stress around the headland.

  2. Spatial variation of earthquake ground motion for application to soil-structure interaction

    SciTech Connect

    Abrahamson, N. )

    1992-03-01

    The spatial variation of strong ground motion from fifteen earthquakes recorded by the Lotung LSST strong motion array is analyzed. The earthquakes range in magnitude from 3.7 to 7.8 and in source distance from 4 to 80 km. In all a total of 533 station pairs are used with station separations ranging from 60 to 85 meters. The spatial variation of ground motion is divided into two parts: variation in the fourier phase (coherence), and variation in the Fourier amplitude. Empirical functions describing the frequency and separation distance dependence of the coherency and amplitude variation appropriate for use in engineering analyses are derived. Taken together, the spatial variation functions given in this study provide a complete description of the statistical properties of the horizontal components of the seismic wavefield assuming plane wave propagation for the S-wave window. Since the S-waves generally cause the largest shaking, these spatial variation functions are appropriate for use in engineering analyses of large structures.

  3. Spatial variation of earthquake ground motion for application to soil-structure interaction. Final report

    SciTech Connect

    Abrahamson, N.

    1992-03-01

    The spatial variation of strong ground motion from fifteen earthquakes recorded by the Lotung LSST strong motion array is analyzed. The earthquakes range in magnitude from 3.7 to 7.8 and in source distance from 4 to 80 km. In all a total of 533 station pairs are used with station separations ranging from 60 to 85 meters. The spatial variation of ground motion is divided into two parts: variation in the fourier phase (coherence), and variation in the Fourier amplitude. Empirical functions describing the frequency and separation distance dependence of the coherency and amplitude variation appropriate for use in engineering analyses are derived. Taken together, the spatial variation functions given in this study provide a complete description of the statistical properties of the horizontal components of the seismic wavefield assuming plane wave propagation for the S-wave window. Since the S-waves generally cause the largest shaking, these spatial variation functions are appropriate for use in engineering analyses of large structures.

  4. Bayesian two-part spatial models for semicontinuous data with application to emergency department expenditures.

    PubMed

    Neelon, Brian; Zhu, Li; Neelon, Sara E Benjamin

    2015-07-01

    In health services research, it is common to encounter semicontinuous data characterized by a point mass at zero and a continuous distribution of positive values. Examples include medical expenditures, in which the zeros represent patients who do not use health services, while the continuous distribution describes the level of expenditures among users. Semicontinuous data are customarily analyzed using two-part mixture models. In the spatial analysis of semicontinuous data, two-part models are especially appealing because they provide a joint picture of how health services utilization and associated expenditures vary across geographic regions. However, when applying these models, careful attention must be paid to distributional choices, as model misspecification can lead to biased and imprecise inferences. This paper introduces a broad class of Bayesian two-part models for the spatial analysis of semicontinuous data. Specific models considered include two-part lognormal, log skew-elliptical, and Bayesian non-parametric models. Multivariate conditionally autoregressive priors are used to link model components and provide spatial smoothing across neighboring regions, resulting in a joint spatial modeling framework for health utilization and expenditures. We develop a fully conjugate Gibbs sampling scheme, leading to efficient posterior computation. We illustrate the approach using data from a recent study of emergency department expenditures. PMID:25649743

  5. Assessing applicability of SWAT calibrated at multiple spatial scales from field to stream

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The capability of SWAT for simulating long-term hydrology and water quality was evaluated using data collected in subwatershed K of the Little River Experimental watershed located in South Atlantic Coastal Plain of the USA. The SWAT model was calibrated to measurements made at various spatial scales...

  6. Digital Hydrologic Networks Supporting Applications Related to Spatially Referenced Regression Modeling

    USGS Publications Warehouse

    Brakebill, J.W.; Wolock, D.M.; Terziotti, S.E.

    2011-01-01

    Digital hydrologic networks depicting surface-water pathways and their associated drainage catchments provide a key component to hydrologic analysis and modeling. Collectively, they form common spatial units that can be used to frame the descriptions of aquatic and watershed processes. In addition, they provide the ability to simulate and route the movement of water and associated constituents throughout the landscape. Digital hydrologic networks have evolved from derivatives of mapping products to detailed, interconnected, spatially referenced networks of water pathways, drainage areas, and stream and watershed characteristics. These properties are important because they enhance the ability to spatially evaluate factors that affect the sources and transport of water-quality constituents at various scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW), a process-based/statistical model, relies on a digital hydrologic network in order to establish relations between quantities of monitored contaminant flux, contaminant sources, and the associated physical characteristics affecting contaminant transport. Digital hydrologic networks modified from the River Reach File (RF1) and National Hydrography Dataset (NHD) geospatial datasets provided frameworks for SPARROW in six regions of the conterminous United States. In addition, characteristics of the modified RF1 were used to update estimates of mean-annual streamflow. This produced more current flow estimates for use in SPARROW modeling. ?? 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA.

  7. Digital hydrologic networks supporting applications related to spatially referenced regression modeling

    USGS Publications Warehouse

    Brakebill, John W.; Wolock, David M.; Terziotti, Silvia

    2011-01-01

    Digital hydrologic networks depicting surface-water pathways and their associated drainage catchments provide a key component to hydrologic analysis and modeling. Collectively, they form common spatial units that can be used to frame the descriptions of aquatic and watershed processes. In addition, they provide the ability to simulate and route the movement of water and associated constituents throughout the landscape. Digital hydrologic networks have evolved from derivatives of mapping products to detailed, interconnected, spatially referenced networks of water pathways, drainage areas, and stream and watershed characteristics. These properties are important because they enhance the ability to spatially evaluate factors that affect the sources and transport of water-quality constituents at various scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW), a process-based ⁄ statistical model, relies on a digital hydrologic network in order to establish relations between quantities of monitored contaminant flux, contaminant sources, and the associated physical characteristics affecting contaminant transport. Digital hydrologic networks modified from the River Reach File (RF1) and National Hydrography Dataset (NHD) geospatial datasets provided frameworks for SPARROW in six regions of the conterminous United States. In addition, characteristics of the modified RF1 were used to update estimates of mean-annual streamflow. This produced more current flow estimates for use in SPARROW modeling.

  8. An Analysis of Spatial Configuration and its Application to Research in Higher Education.

    ERIC Educational Resources Information Center

    Cole, Nancy S.; Cole, James W. L.

    This paper presents an analysis of the spatial configuration of variables in a multivariate system. The purpose of the analysis is to make clearer the relationships among the variables by locating them in a minimally-dimensioned space. Similarly, individuals are located in the smaller space and related to each other on the basis of the variables…

  9. SU-E-P-30: Clinical Applications of Spatially Fractionated Radiation Therapy (GRID) Using Helical Tomotherapy

    SciTech Connect

    Zhang, X; Liang, X; Penagaricano, J; Morrill, S; Corry, P; Paudel, N; Vaneerat, V Ratanatharathorn; Yan, Y; Griffin, R

    2015-06-15

    Purpose: To present the first clinical applications of Helical Tomotherapy-based spatially fractionated radiotherapy (HT-GRID) for deep seated tumors and associated dosimetric study. Methods: Ten previously treated GRID patients were selected (5 HT-GRID and 5 LINAC-GRID using a commercially available GRID block). Each case was re-planned either in HT-GRID or LINAC-GRID for a total of 10 plans for both techniques using same prescribed dose of 20 Gy to maximum point dose of GRID GTV. For TOMO-GRID, a programmable virtual TOMOGRID template mimicking a GRID pattern was generated. Dosimetric parameters compared included: GRID GTV mean dose (Dmean) and equivalent uniform dose (EUD), GRID GTV dose inhomogeneity (Ratio(valley/peak)), normal tissue Dmean and EUD, and other organs-at-risk(OARs) doses. Results: The median tumor volume was 634 cc, ranging from 182 to 4646 cc. Median distance from skin to the deepest part of tumor was 22cm, ranging from 8.9 to 38cm. The median GRID GTV Dmean and EUD was 10.65Gy (9.8–12.5Gy) and 7.62Gy (4.31–11.06Gy) for HT-GRID and was 6.73Gy (4.44–8.44Gy) and 3.95Gy (0.14–4.2Gy) for LINAC-GRID. The median Ratio(valley/peak) was 0.144(0.05–0.29) for HT-GRID and was 0.055(0.0001–0.14) for LINAC-GRID. For normal tissue in HT-GRID, the median Dmean and EUD was 1.24Gy (0.34–2.54Gy) and 5.45 Gy(3.45–6.89Gy) and was 0.61 Gy(0.11–1.52Gy) and 6Gy(4.45–6.82Gy) for LINAC-GRID. The OAR doses were comparable between the HT-GRID and LINAC-GRID. However, in some cases it was not possible to avoid a critical structure in LINAC-GRID; while HT-GRID can spare more tissue doses for certain critical structures. Conclusion: HT-GRID delivers higher GRID GTV Dmean, EUD and Ratio(valley/peak) compared to LINAC-GRID. HT-GRID delivers higher Dmean and lower EUD for normal tissue compared to LINAC-GRID. TOMOGRID template can be highly patient-specific and allows adjustment of the GRID pattern to different tumor sizes and shapes when they are deeply

  10. A Novel Fixed Low-Rank Constrained EEG Spatial Filter Estimation with Application to Movie-Induced Emotion Recognition

    PubMed Central

    Suyama, Takayuki

    2016-01-01

    This paper proposes a novel fixed low-rank spatial filter estimation for brain computer interface (BCI) systems with an application that recognizes emotions elicited by movies. The proposed approach unifies such tasks as feature extraction, feature selection, and classification, which are often independently tackled in a “bottom-up” manner, under a regularized loss minimization problem. The loss function is explicitly derived from the conventional BCI approach and solves its minimization by optimization with a nonconvex fixed low-rank constraint. For evaluation, an experiment was conducted to induce emotions by movies for dozens of young adult subjects and estimated the emotional states using the proposed method. The advantage of the proposed method is that it combines feature selection, feature extraction, and classification into a monolithic optimization problem with a fixed low-rank regularization, which implicitly estimates optimal spatial filters. The proposed method shows competitive performance against the best CSP-based alternatives. PMID:27597862

  11. A Novel Fixed Low-Rank Constrained EEG Spatial Filter Estimation with Application to Movie-Induced Emotion Recognition.

    PubMed

    Yano, Ken; Suyama, Takayuki

    2016-01-01

    This paper proposes a novel fixed low-rank spatial filter estimation for brain computer interface (BCI) systems with an application that recognizes emotions elicited by movies. The proposed approach unifies such tasks as feature extraction, feature selection, and classification, which are often independently tackled in a "bottom-up" manner, under a regularized loss minimization problem. The loss function is explicitly derived from the conventional BCI approach and solves its minimization by optimization with a nonconvex fixed low-rank constraint. For evaluation, an experiment was conducted to induce emotions by movies for dozens of young adult subjects and estimated the emotional states using the proposed method. The advantage of the proposed method is that it combines feature selection, feature extraction, and classification into a monolithic optimization problem with a fixed low-rank regularization, which implicitly estimates optimal spatial filters. The proposed method shows competitive performance against the best CSP-based alternatives. PMID:27597862

  12. Evaluation of geostatistical estimators and their applicability to characterise the spatial patterns of recreational fishing catch rates

    PubMed Central

    Aidoo, Eric N.; Mueller, Ute; Goovaerts, Pierre; Hyndes, Glenn A.

    2015-01-01

    Western Australians are heavily engaged in recreational fishing activities with a participation rate of approximately 30%. An accurate estimation of the spatial distribution of recreational catch per unit effort (catch rates) is an integral component for monitoring fish population changes and to develop strategies for ecosystem-based marine management. Geostatistical techniques such as kriging can provide useful tools for characterising the spatial distributions of recreational catch rates. However, most recreational fishery data are highly skewed, zero-inflated and when expressed as ratios are impacted by the small number problem which can influence the estimates obtained from the traditional kriging. The applicability of ordinary, indicator and Poisson kriging to recreational catch rate data was evaluated for three aquatic species with different behaviours and distribution patterns. The prediction performance of each estimator was assessed based on cross-validation. For all three species, the accuracy plot of the indicator kriging (IK) showed a better agreement between expected and empirical proportions of catch rate data falling within probability intervals of increasing size, as measured by the goodness statistic. Also, indicator kriging was found to be better in predicting the latent catch rate for the three species compared to ordinary and Poisson kriging. For each species, the spatial maps from the three estimators displayed similar patterns but Poisson kriging produced smoother spatial distributions. We show that the IK estimator may be preferable for the spatial modelling of catch rate data exhibiting these characteristics, and has the best prediction performance regardless of the life history and distribution patterns of those three species. PMID:26120221

  13. Mutual information spectrum for selection of event-related spatial components. Application to eloquent motor cortex mapping

    PubMed Central

    Ossadtchi, Alexei; Pronko, Platon; Baillet, Sylvain; Pflieger, Mark E.; Stroganova, Tatiana

    2014-01-01

    Spatial component analysis is often used to explore multidimensional time series data whose sources cannot be measured directly. Several methods may be used to decompose the data into a set of spatial components with temporal loadings. Component selection is of crucial importance, and should be supported by objective criteria. In some applications, the use of a well defined component selection criterion may provide for automation of the analysis. In this paper we describe a novel approach for ranking of spatial components calculated from the EEG or MEG data recorded within evoked response paradigm. Our method is called Mutual Information (MI) Spectrum and is based on gauging the amount of MI of spatial component temporal loadings with a synthetically created reference signal. We also describe the appropriate randomization based statistical assessment scheme that can be used for selection of components with statistically significant amount of MI. Using simulated data with realistic trial to trial variations and SNR corresponding to the real recordings we demonstrate the superior performance characteristics of the described MI based measure as compared to a more conventionally used power driven gauge. We also demonstrate the application of the MI Spectrum for the selection of task-related independent components from real MEG data. We show that the MI spectrum allows to identify task-related components reliably in a consistent fashion, yielding stable results even from a small number of trials. We conclude that the proposed method fits naturally the information driven nature of ICA and can be used for routine and automatic ranking of independent components calculated from the functional neuroimaging data collected within event-related paradigms. PMID:24478692

  14. High-fidelity spatially resolved multiphoton counting for quantum imaging applications.

    PubMed

    Chrapkiewicz, Radosław; Wasilewski, Wojciech; Banaszek, Konrad

    2014-09-01

    We present a method for spatially resolved multiphoton counting based on an intensified camera with the retrieval of multimode photon statistics fully accounting for nonlinearities in the detection process. The scheme relies on one-time quantum tomographic calibration of the detector. Faithful, high-fidelity reconstruction of single- and two-mode statistics of multiphoton states is demonstrated for coherent states and their statistical mixtures. The results consistently exhibit classical values of the Mandel parameter and the noise reduction factor in contrast to raw statistics of camera photo-events. Detector operation is reliable for illumination levels up to the average of one detected photon per an event area-substantially higher than in previous approaches to characterize quantum statistical properties of light with spatial resolution. PMID:25166081

  15. Spatial glass transition temperature variations in polymer glass: application to a maltodextrin-water system.

    PubMed

    van Sleeuwen, Rutger M T; Zhang, Suying; Normand, Valéry

    2012-03-12

    A model was developed to predict spatial glass transition temperature (T(g)) distributions in glassy maltodextrin particles during transient moisture sorption. The simulation employed a numerical mass transfer model with a concentration dependent apparent diffusion coefficient (D(app)) measured using Dynamic Vapor Sorption. The mass average moisture content increase and the associated decrease in T(g) were successfully modeled over time. Large spatial T(g) variations were predicted in the particle, resulting in a temporary broadening of the T(g) region. Temperature modulated differential scanning calorimetry confirmed that the variation in T(g) in nonequilibrated samples was larger than in equilibrated samples. This experimental broadening was characterized by an almost doubling of the T(g) breadth compared to the start of the experiment. Upon reaching equilibrium, both the experimental and predicted T(g) breadth contracted back to their initial value. PMID:22268547

  16. A Bayesian network approach to knowledge integration and representation of farm irrigation: 3. Spatial application

    NASA Astrophysics Data System (ADS)

    Robertson, D. E.; Wang, Q. J.; McAllister, A. T.; Abuzar, M.; Malano, H. M.; Etchells, T.

    2009-02-01

    Catchment managers are interested in understanding impacts of the management options they promote at both farm and regional scales. In this third paper of this series, we use Inteca-Farm, a Bayesian network model of farm irrigation in the Shepparton Irrigation Region of northern Victoria, Australia, to assess the current condition of management outcome measures and the impact of historical and future management intervention. To help overcome difficulties in comprehending modeling results that are expressed as probability distributions, to capture uncertainties, we introduce methods to spatially display and compare the output from Bayesian network models and to use these methods to compare model predictions for three management scenarios. Model predictions suggest that management intervention has made a substantial improvement to the condition of management outcome measures and that further improvements are possible. The results highlight that the management impacts are spatially variable, which demonstrates that farm modeling can provide valuable evidence in substantiating the impact of catchment management intervention.

  17. Spatial Analysis and GIS Applications for Estimating Monthly Rainfall Totals on Mauritius

    NASA Astrophysics Data System (ADS)

    Staub, C. G.; Stevens, F. R.; Waylen, P. R.

    2015-12-01

    Reliable gridded rainfall data are critical for GIS-based climate change impact assessments, water resources planning and management, design of hydraulic works and urban development. Small Island Developing States (SIDS) are highly dependent on rainfall, more sensitive, and have a lower adaptive capacity to climate change than mainland countries yet are poorly studied. Extensive hydrometeorological records exist in Mauritius, offering a unique opportunity to model rainfall distribution and produce high resolution gridded datasets for GIS-based models. Multiple regression is used to model mean annual and monthly rainfall on the island for the period 1997 - 2011 and derive a physical basis for understanding spatial rainfall patterns. The models incorporate latitude, longitude, slope, distance to coast, elevation and their interactions accounting for 68% of the variance in mean annual rainfall and 55-72% of variance in mean monthly rainfall across the island. Spatial trends are removed from observed monthly rainfall totals and ordinary kriging is applied to the residuals. The regression and kriging results are combined to produce a high resolution, physically consistent gridded time-series dataset. Estimate and variance values from each month are then used to calculate 95% confidence interval surfaces. Cross-validation reveals close correspondence between predicted and observed values. This regression kriging approach captures what is currently understood about the spatial and temporal variability of precipitation in this mountainous sub-tropical location, giving us greater confidence in the reliability of the new rainfall estimates.

  18. 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

  19. In Vivo Application of Short-Lag Spatial Coherence Imaging in Human Liver

    PubMed Central

    Jakovljevic, Marko; Trahey, Gregg E.; Nelson, Rendon C.; Dahl, Jeremy J.

    2013-01-01

    We present the results of a patient study conducted to assess the performance of two novel imaging methods, namely Short-Lag Spatial Coherence (SLSC) and Harmonic Spatial Coherence Imaging (HSCI), in in vivo liver environment. Similar in appearance to the B-mode images, SLSC and HSCI images are based solely on the spatial coherence of fundamental and harmonic echo data, respectively, and do not depend on the echo magnitude. SLSC and HSCI suppress incoherent echo signals and thus tend to reduce clutter. The SLSC and HSCI images of 17 patients demonstrate sharper delineation of blood vessel walls, suppressed clutter inside the vessel lumen, and show reduced speckle in surrounding tissue compared to matched B-modes. Target contrast and contrast-to-noise ratio (CNR) show statistically significant improvements between fundamental B-mode and SLSC imaging and between harmonic B-mode and HSCI imaging (in all cases p < 0.01). The magnitude of improvement in contrast and CNR increases as the overall quality of B-mode images decreases. Poor quality fundamental B-mode images (where image quality classification is based on both contrast and CNR) exhibit the highest improvements in both contrast and CNR (288 % improvement in contrast and 533 % improvement in CNR). PMID:23347642

  20. Extending Lkn Climate Regionalization with Spatial Regularization: AN Application to Epidemiological Research

    NASA Astrophysics Data System (ADS)

    Liss, Alexander; Gel, Yulia R.; Kulinkina, Alexandra; Naumova, Elena N.

    2016-06-01

    Regional climate is a critical factor in public health research, adaptation studies, climate change burden analysis, and decision support frameworks. Existing climate regionalization schemes are not well suited for these tasks as they rarely take population density into account. In this work, we are extending our recently developed method for automated climate regionalization (LKN-method) to incorporate the spatial features of target population. The LKN method consists of the data limiting step (L-step) to reduce dimensionality by applying principal component analysis, a classification step (K-step) to produce hierarchical candidate regions using k-means unsupervised classification algorithm, and a nomination step (N-step) to determine the number of candidate climate regions using cluster validity indexes. LKN method uses a comprehensive set of multiple satellite data streams, arranged as time series, and allows us to define homogeneous climate regions. The proposed approach extends the LKN method to include regularization terms reflecting the spatial distribution of target population. Such tailoring allows us to determine the optimal number and spatial distribution of climate regions and thus, to ensure more uniform population coverage across selected climate categories. We demonstrate how the extended LKN method produces climate regionalization can be better tailored to epidemiological research in the context of decision support framework.

  1. 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

  2. Visualization and Analysis of Wireless Sensor Network Data for Smart Civil Structure Applications Based On Spatial Correlation Technique

    NASA Astrophysics Data System (ADS)

    Chowdhry, Bhawani Shankar; White, Neil M.; Jeswani, Jai Kumar; Dayo, Khalil; Rathi, Manorma

    2009-07-01

    Disasters affecting infrastructure, such as the 2001 earthquakes in India, 2005 in Pakistan, 2008 in China and the 2004 tsunami in Asia, provide a common need for intelligent buildings and smart civil structures. Now, imagine massive reductions in time to get the infrastructure working again, realtime information on damage to buildings, massive reductions in cost and time to certify that structures are undamaged and can still be operated, reductions in the number of structures to be rebuilt (if they are known not to be damaged). Achieving these ideas would lead to huge, quantifiable, long-term savings to government and industry. Wireless sensor networks (WSNs) can be deployed in buildings to make any civil structure both smart and intelligent. WSNs have recently gained much attention in both public and research communities because they are expected to bring a new paradigm to the interaction between humans, environment, and machines. This paper presents the deployment of WSN nodes in the Top Quality Centralized Instrumentation Centre (TQCIC). We created an ad hoc networking application to collect real-time data sensed from the nodes that were randomly distributed throughout the building. If the sensors are relocated, then the application automatically reconfigures itself in the light of the new routing topology. WSNs are event-based systems that rely on the collective effort of several micro-sensor nodes, which are continuously observing a physical phenomenon. WSN applications require spatially dense sensor deployment in order to achieve satisfactory coverage. The degree of spatial correlation increases with the decreasing inter-node separation. Energy consumption is reduced dramatically by having only those sensor nodes with unique readings transmit their data. We report on an algorithm based on a spatial correlation technique that assures high QoS (in terms of SNR) of the network as well as proper utilization of energy, by suppressing redundant data transmission

  3. 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

  4. Compact, transmissive two-dimensional spatial disperser design with application in simultaneous endoscopic imaging and laser microsurgery.

    PubMed

    Metz, Philipp; Adam, Jost; Gerken, Martina; Jalali, Bahram

    2014-01-20

    Minimally invasive surgery procedures benefit from a reduced size of endoscopic devices. A prospective path to implement miniaturized endoscopy is single optical-fiber-based spectrally encoded imaging. While simultaneous spectrally encoded inertial-scan-free imaging and laser microsurgery have been successfully demonstrated in a large table setup, a highly miniaturized optical design would promote the development of multipurpose endoscope heads. This paper presents a highly scalable, entirely transmissive axial design for a spectral 2D spatial disperser. The proposed design employs a grating prism and a virtual imaged phased array (VIPA). Based on semi-analytical device modeling, we performed a systematic parameter analysis to assess the spectral disperser's manufacturability and to obtain an optimum application-specific design. We found that, in particular, a low grating period combined with a high optical input bandwidth and low VIPA tilt showed favorable results in terms of a high spatial resolution, a small device diameter, and a large field of view. Our calculations reveal that a reasonable imaging performance can be achieved with system diameters of below 5 mm, which renders the proposed 2D spatial disperser design highly suitable for use in future endoscope heads that combine mechanical-scan-free imaging and laser microsurgery. PMID:24514122

  5. 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

  6. MALDI Imaging Mass Spectrometry (MALDI-IMS)—Application of Spatial Proteomics for Ovarian Cancer Classification and Diagnosis

    PubMed Central

    Gustafsson, Johan O. R.; Oehler, Martin K.; Ruszkiewicz, Andrew; McColl, Shaun R.; Hoffmann, Peter

    2011-01-01

    MALDI imaging mass spectrometry (MALDI-IMS) allows acquisition of mass data for metabolites, lipids, peptides and proteins directly from tissue sections. IMS is typically performed either as a multiple spot profiling experiment to generate tissue specific mass profiles, or a high resolution imaging experiment where relative spatial abundance for potentially hundreds of analytes across virtually any tissue section can be measured. Crucially, imaging can be achieved without prior knowledge of tissue composition and without the use of antibodies. In effect MALDI-IMS allows generation of molecular data which complement and expand upon the information provided by histology including immuno-histochemistry, making its application valuable to both cancer biomarker research and diagnostics. The current state of MALDI-IMS, key biological applications to ovarian cancer research and practical considerations for analysis of peptides and proteins on ovarian tissue are presented in this review. PMID:21340013

  7. Spatial and Temporal Variability in Pesticide Exposure Downstream of a Heavily Irrigated Cropping Area: Application of Different Monitoring Techniques.

    PubMed

    O'Brien, Dominique; Lewis, Stephen; Davis, Aaron; Gallen, Christie; Smith, Rachael; Turner, Ryan; Warne, Michael; Turner, Scott; Caswell, Stewart; Mueller, Jochen F; Brodie, Jon

    2016-05-25

    Pesticide exposure threatens many freshwater and estuarine ecosystems around the world. This study examined the temporal and spatial trends of pesticide concentrations in a waterway within an agriculturally developed dry-tropics catchment using a combination of grab and passive sampling methods over a continuous two-year monitoring program. A total of 43 pesticide residues were detected with 7 pesticides exceeding ecologically relevant water quality guidelines/trigger values during the study period and 4 (ametryn, atrazine, diuron, and metolachlor) of these exceeding guidelines for several months. The presence and concentration of the pesticides in the stream coincided with seasonal variability in rainfall, harvest timing/cropping cycle, and management changes. The sampling approach used demonstrates that the application of these complementary sampling techniques (both grab and passive sampling methods) was effective in establishing pesticide usage patterns in upstream locations where application data are unavailable. PMID:26755130

  8. Spatial input variables applications for hydrological simulation of south Wyoming watershed: case study of Muddy Creek via MIKE SHE

    NASA Astrophysics Data System (ADS)

    Liu, T.; Miller, S. N.; Chitrakar, S.

    2013-12-01

    With the abundant online data sources, there are great advantages of hydrological simulation for the American watershed management. Not only are the conventional station-based data conveniently accessible, but also the spatial data provide the great possibility for the hydrological approaches. This case study demonstrates the possible applications and access source for the hydrological modeling, which might be used as reference. The modeling input time series or parameters origins from various sources: precipitation is from TRMM (as spatial input of hydrological model) and NOAA (station-based), evapotranspiration came from (NASA MODIS platform via ArcGIS access), temperature is delivered by NOAA database (station-based) and NASA MODIS (spatial input), the snow mask and depth also can be obtained from NOAA, NASA MODIS and NRCS, discharge data might be from USGS hydro-climate data network (HCDN). The parameters of static state are surely complete such as DEM contributed by STRM of NASA, soil related data from SSURGO and landuse related data obtained from USGS. The different institutes might focus on different aspects, temporal span, geo-locations. But supported by the various sources of data, the hydrological modeling can be setup solidly by interpolating the various data. The daily time step simulation is manually calibrated for 1 year period referred by 4 discharge gauging stations, as well as 1 year of validation period. Simulation resolution is uniformed to 200m*200m cells size according the 2600km2 of watershed domain. The case study demonstrates that the station-based and spatial data could cooperate each other and support the accurate hydrological modeling during. Based on the established model, it can be further extended for the assessment of water quality impact and sediment transportation simulation. The final goal the modeling approach is to serve the land management on hydrological response.

  9. Spatially uniform and nonuniform analyses of electroencephalographic dynamics,with application to the topography of the alpha rhythm

    NASA Astrophysics Data System (ADS)

    O'Connor, S. C.; Robinson, P. A.

    2004-07-01

    Corticothalamic dynamics are investigated using a model in which spatial nonuniformities are incorporated via the coupling of spatial eigenmodes. Comparison of spectra generated using the nonuniform analysis with those generated using a uniform one demonstrates that, for most frequencies, local activity is only weakly dependent on activity elsewhere in the cortex; however, dispersion of low-wave-number activity ensures that distant dynamics influence local dynamics at low frequencies (below approximately 2Hz ), and at the alpha frequency (approximately 10Hz ), where propagating signals are inherently weakly damped, and wavelengths are large. When certain model parameters have similar spatial profiles, as is expected from physiology, the low-frequency discrepancies tend to cancel, and the uniform analysis with local parameter values is an adequate approximation to the full nonuniform one across the whole spectrum, at least for large-scale nonuniformities. After comparing the uniform and nonuniform analyses, we consider one possible application of the nonuniform analysis: studying the phenomenon of occipital alpha dominance, whereby the alpha frequency and power are greater at the back of the head (occipitally) than at the front. In order to infer realistic nonuniformities in the model parameters, the uniform version of the model is first fitted to data recorded from 98 normal subjects in a waking, eyes-closed state. This yields a set of parameters at each of five electrode sites along the midline. The inferred parameter nonuniformities are consistent with anatomical and physiological constraints. Introducing these spatial profiles into the full nonuniform model then quantitatively reproduces observed site-dependent variations in the alpha power and frequency. The results confirm that the frequency shift is mainly due to a decrease in the corticothalamic propagation delay, but indicate that the delay nonuniformity cannot account for the observed occipital increase in

  10. Bandwidth of the contrast sensitivity function as an index of spatial vision with application to refraction.

    PubMed

    Jiang, B C; Scialfa, C T; Tyrrell, R A; Garvey, P M; Leibowitz, H W

    1990-04-01

    The contrast sensitivity function (CSF), although containing more information than traditional measures of acuity, has found difficulty gaining clinical acceptance. The hesitancy of clinicians to adopt the CSF stems, in part, from the fact that it is not as readily interpreted as is acuity. In order to facilitate such interpretation, five indices of spatial vision which are derivable from the CSF were examined in a sample of 287 persons aged 5 to 85 years. All indices were found to be both age-sensitive and strongly related to each other, but bandwidth of the CSF was chosen as a practical index for clinical settings. In a second study, acuity and CSF bandwidth were measured under 0 to +/- 1 D optical blur. It was found that the correction providing best acuity also maximized CSF bandwidth, and that bandwidth was more sensitive to optical blur than was acuity. Results support the assertion that CSF bandwidth is a readily interpreted index of spatial vision that can be measured efficiently within the context of clinical refraction. PMID:2342788

  11. SEHR-ECHO v1.0: a Spatially Explicit Hydrologic Response model for ecohydrologic applications

    NASA Astrophysics Data System (ADS)

    Schaefli, B.; Nicótina, L.; Imfeld, C.; Da Ronco, P.; Bertuzzo, E.; Rinaldo, A.

    2014-11-01

    This paper presents the Spatially Explicit Hydrologic Response (SEHR) model developed at the Laboratory of Ecohydrology of the Ecole Polytechnique Fédérale de Lausanne for the simulation of hydrological processes at the catchment scale. The key concept of the model is the formulation of water transport by geomorphologic travel time distributions through gravity-driven transitions among geomorphic states: the mobilization of water (and possibly dissolved solutes) is simulated at the subcatchment scale and the resulting responses are convolved with the travel paths distribution within the river network to obtain the hydrologic response at the catchment outlet. The model thus breaks down the complexity of the hydrologic response into an explicit geomorphological combination of dominant spatial patterns of precipitation input and of hydrologic process controls. Nonstationarity and nonlinearity effects are tackled through soil moisture dynamics in the active soil layer. We present here the basic model set-up for precipitation-runoff simulation and a detailed discussion of its parameter estimation and of its performance for the Dischma River (Switzerland), a snow-dominated catchment with a small glacier cover.

  12. Spatial analysis of electricity demand patterns in Greece: Application of a GIS-based methodological framework

    NASA Astrophysics Data System (ADS)

    Tyralis, Hristos; Mamassis, Nikos; Photis, Yorgos N.

    2016-04-01

    We investigate various uses of electricity demand in Greece (agricultural, commercial, domestic, industrial use as well as use for public and municipal authorities and street lightning) and we examine their relation with variables such as population, total area, population density and the Gross Domestic Product. The analysis is performed on data which span from 2008 to 2012 and have annual temporal resolution and spatial resolution down to the level of prefecture. We both visualize the results of the analysis and we perform cluster and outlier analysis using the Anselin local Moran's I statistic as well as hot spot analysis using the Getis-Ord Gi* statistic. The definition of the spatial patterns and relationships of the aforementioned variables in a GIS environment provides meaningful insight and better understanding of the regional development model in Greece and justifies the basis for an energy demand forecasting methodology. Acknowledgement: This research has been partly financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: ARISTEIA II: Reinforcement of the interdisciplinary and/ or inter-institutional research and innovation (CRESSENDO project; grant number 5145).

  13. Spatially resolved spectroscopic measurements of a dielectric barrier discharge plasma jet applicable for soft ionization

    NASA Astrophysics Data System (ADS)

    Olenici-Craciunescu, S. B.; Müller, S.; Michels, A.; Horvatic, V.; Vadla, C.; Franzke, J.

    2011-03-01

    An atmospheric pressure microplasma ionization source based on a dielectric barrier discharge with a helium plasma cone outside the electrode region has been developed for liquid chromatography/mass spectrometry and as ionization source for ion mobility spectrometry. It turned out that dielectric barrier discharge ionization could be regarded as a soft ionization technique characterized by only minor fragmentation similar to atmospheric pressure chemical ionization (APCI). Mainly protonated molecules were detected. In order to characterize the soft ionization mechanism spatially resolved optical emission spectrometry (OES) measurements were performed on plasma jets burning either in He or in Ar. Besides to spatial intensity distributions of noble gas spectral lines, in both cases a special attention was paid to lines of N 2+ and N 2. The obtained mapping of the plasma jet shows very different number density distributions of relevant excited species. In the case of helium plasma jet, strong N 2+ lines were observed. In contrast to that, the intensities of N 2 lines in Ar were below the present detection limit. The positions of N 2+ and N 2 distribution maxima in helium indicate the regions where the highest efficiency of the water ionization and the protonation process is expected.

  14. Development and application of a spatial hydrology model of Okefenokee Swamp, Georgia

    USGS Publications Warehouse

    Loftin, C.S.; Kitchens, W.M.; Ansay, N.

    2001-01-01

    The model described herein was used to assess effects of the Suwannee River sill (a low earthen dam constructed to impound the Suwannee River within the Okefenokee National Wildlife Refuge to eliminate wildfires) on the hydrologic environment of Okefenokee Swamp, Georgia. Developed with Arc/Info Macro Language routines in the GRID environment, the model distributes water in the swamp landscape using precipitation, inflow, evapotranspiration, outflow, and standing water. Water movement direction and rate are determined by the neighborhood topographic gradient, determined using survey grade Global Positioning Systems technology. Model data include flow rates from USGS monitored gauges, precipitation volumes and water levels measured within the swamp, and estimated evapotranspiration volumes spatially modified by vegetation type. Model output in semi-monthly time steps includes water depth, water surface elevation above mean sea level, and movement direction and volume. Model simulations indicate the sill impoundment affects 18 percent of the swamp during high water conditions when wildfires are scarce and has minimal spatial effect (increasing hydroperiods in less than 5 percent of the swamp) during low water and drought conditions when fire occurrence is high but precipitation and inflow volumes are limited.

  15. A mobile system for quantifying the spatial variability of the surface energy balance: design and application

    NASA Astrophysics Data System (ADS)

    Wohlfahrt, Georg; Tasser, Erich

    2015-05-01

    We present a mobile device for the quantification of the small-scale (a few square meters) spatial variability in the surface energy balance components and several auxiliary variables of short-statured (<1 m) canopies. The key element of the mobile device is a handheld four-component net radiometer for the quantification of net radiation, albedo and infrared surface temperature, which is complemented with measurements of air temperature, wind speed, soil temperature and soil water content. Data are acquired by a battery-powered data logger, which is mounted on a backpack together with the auxiliary sensors. The proposed device was developed to bridge between the spatial scales of satellite/airborne remote sensing and fixed, stationary tower-based measurements with an emphasis on micrometeorological, catchment hydrological and landscape-ecological research questions. The potential of the new device is demonstrated through four selected case studies, which cover the issues of net radiation heterogeneity within the footprint of eddy covariance flux measurements due to (1) land use and (2) slope and aspect of the underlying surface, (3) controls on landscape-scale variability in soil temperature and albedo and (4) the estimation of evapotranspiration based exclusively on measurements with the mobile device.

  16. A mobile system for quantifying the spatial variability of the surface energy balance: design and application

    NASA Astrophysics Data System (ADS)

    Tasser, Erich; Wohlfahrt, Georg

    2014-05-01

    We present a mobile device for the quantification of the small-scale spatial variability in the surface energy balance components and several auxiliary variables of short-statured canopies. The key element of the mobile device is a hand-held four-component net radiometer for the quantification of net radiation, albedo and infrared surface temperature, which is complemented with measurements of air temperature, wind speed, soil temperature and soil water content. Data are acquired by a battery-powered data logger, which is mounted on a backpack together with the auxiliary sensors. The proposed device was developed to bridge between the spatial scales of satellite/airborne remote sensing and fixed, stationary tower-based measurements with an emphasis on micrometeorological, catchment hydrological and landscape-ecological research questions. The potential of the new device is demonstrated through four selected case studies, which cover the issues of net radiation heterogeneity within the footprint of eddy covariance flux measurements due to (i) land use and (ii) slope and aspect of the underlying surface, (iii) controls on landscape-scale variability in soil temperature and albedo, and (iv) the estimation of evapotranspiration based exclusively on measurements with the mobile device.

  17. A mobile system for quantifying the spatial variability of the surface energy balance: design and application.

    PubMed

    Wohlfahrt, Georg; Tasser, Erich

    2015-05-01

    We present a mobile device for the quantification of the small-scale (a few square meters) spatial variability in the surface energy balance components and several auxiliary variables of short-statured (<1 m) canopies. The key element of the mobile device is a handheld four-component net radiometer for the quantification of net radiation, albedo and infrared surface temperature, which is complemented with measurements of air temperature, wind speed, soil temperature and soil water content. Data are acquired by a battery-powered data logger, which is mounted on a backpack together with the auxiliary sensors. The proposed device was developed to bridge between the spatial scales of satellite/airborne remote sensing and fixed, stationary tower-based measurements with an emphasis on micrometeorological, catchment hydrological and landscape-ecological research questions. The potential of the new device is demonstrated through four selected case studies, which cover the issues of net radiation heterogeneity within the footprint of eddy covariance flux measurements due to (1) land use and (2) slope and aspect of the underlying surface, (3) controls on landscape-scale variability in soil temperature and albedo and (4) the estimation of evapotranspiration based exclusively on measurements with the mobile device. PMID:25063050

  18. 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.

  19. Application of land use regression modelling to assess the spatial distribution of road traffic noise in three European cities.

    PubMed

    Aguilera, Inmaculada; Foraster, Maria; Basagaña, Xavier; Corradi, Elisabetta; Deltell, Alexandre; Morelli, Xavier; Phuleria, Harish C; Ragettli, Martina S; Rivera, Marcela; Thomasson, Alexandre; Slama, Rémy; Künzli, Nino

    2015-01-01

    Noise prediction models and noise maps are used to estimate the exposure to road traffic noise, but their availability and the quality of the noise estimates is sometimes limited. This paper explores the application of land use regression (LUR) modelling to assess the long-term intraurban spatial variability of road traffic noise in three European cities. Short-term measurements of road traffic noise taken in Basel, Switzerland (n=60), Girona, Spain (n=40), and Grenoble, France (n=41), were used to develop two LUR models: (a) a "GIS-only" model, which considered only predictor variables derived with Geographic Information Systems; and (b) a "Best" model, which in addition considered the variables collected while visiting the measurement sites. Both noise measurements and noise estimates from LUR models were compared with noise estimates from standard noise models developed for each city by the local authorities. Model performance (adjusted R(2)) was 0.66-0.87 for "GIS-only" models, and 0.70-0.89 for "Best" models. Short-term noise measurements showed a high correlation (r=0.62-0.78) with noise estimates from the standard noise models. LUR noise estimates did not show any systematic differences in the spatial patterns when compared with those from standard noise models. LUR modelling with accurate GIS source data can be a promising tool for noise exposure assessment with applications in epidemiological studies. PMID:25227731

  20. Application of Geo-Spatial Techniques for Precise Demarcation of Village/Panchayat Boundaries

    NASA Astrophysics Data System (ADS)

    Rao, S. S.; Banu, V.; Tiwari, A.; Bahuguna, S.; Uniyal, S.; Chavan, S. B.; Murthy, M. V. R.; Arya, V. S.; Nagaraja, R.; Sharma, J. R.

    2014-11-01

    In order to achieve the overall progress of the country with active and effective participation of all sections of society, the 12th Five Year Plan (FYP) would bring Panchayats centre-stage and achieve the inclusive growth agenda through inclusive governance. The concept of 'democratic decentralization' in the form of a three-tier administration was introduced in the name of "Panchayat Raj". Horizontally, it is a network of village Panchayats. Vertically, it is an organic growth of Panchayats rising up to national level. The Ministry of Panchayati Raj has three broad agenda: Empowerment, Enablement and Accountability. Space based Information Support for Decentralized Planning (SIS-DP) is one of the initiatives taken by Govt. of India with ISRO/DOS for generation and dissemination of spatial information for planning at the grass root level. The boundary layer for villages across different states/district/block is available with line departments. Most of these data exist at a much generalized scale. These boundaries do not overlay exactly with that of ground realities and may not be suitable for accurate analysis in terms of area, shape, position, etc. To deal with this problem, a strategy is adopted, which makes use of High Resolution Satellite Imagery (HRSI) from Indian Remote sensing satellites and cadastral maps at 1:4000 scale integrated with GIS techniques to enhance the accuracy of geo-spatial depiction of Village/Panchayat boundaries. Cadastral maps are used to depict the boundaries of land parcels and other features at the village level. These maps are registered to ortho products of HRSI using Ground Control Points. The cadastral maps are precisely overlaid on ortho-rectified HRSI and each parcel vertex is tagged with the real-world geographical coordinates. Village boundaries are extracted from the geo-referenced village cadastral maps. These boundaries are fine-tuned by considering under lap and overlap of neighboring villages and a mosaic is generated at

  1. Spatial three-dimensional landslide susceptibility mapping tool and its applications

    NASA Astrophysics Data System (ADS)

    Xie, Mowen; Tetsuro, Esaki; Qiu, Cheng; Jia, Lin

    There are three methods of zoning landslide susceptibility: qualitative, statistical methodologies, and geotechnical model. Qualitative approaches are based on the judgment of those conducting the susceptibility or hazard assessment; the statistical approach uses a predictive function or index derived from a combination of weighted factors; and the deterministic, or physically based, models are based on the physical laws of conservation of mass, energy, and momentum. Two-dimensional deterministic models are widely used in the design of civil engineering, and the infinite slope model (one-dimensional) is always employed in the deterministic-model-based landslide hazard mapping. This article presents a new GIS (Geographic Information Systems)-based landslide susceptibility mapping system which can be used to identify the three-dimensional (3-D) landslide bodies from complex topography. All slope-related spatial information (vector or raster dataset) was integrated in the system, by dividing the study area into slope units and assuming the initial slip to be the lower part of an ellipsoid. The 3-D critical slip surface in the 3-D slope stability analysis was located by minimizing the 3-D safety factor using the Monte Carlo random simulation. The failure probability of the landslide was calculated using an approximate method in which effective cohesion, effective friction angle, and 3-D safety factor were assumed to be in normal distribution. A computational program called 3-DSlopeGIS, in which a GIS Developer kit (ArcObjects of ESRI) had been used to fulfill the GIS spatial analysis function and effective data management, has been developed to implement all the calculations of the 3-D slope problem. By using the spatial analysis functions, the data management, and the visualization of GIS for processing the complicated slope-related data, the 3-D slope stability problem is easier to be studied through a friendly visual graphical user interface. The system has been

  2. Passive microwave derived snowmelt timing: significance, spatial and temporal variability, and potential applications

    NASA Astrophysics Data System (ADS)

    Semmens, Kathryn Alese

    Snow accumulation and melt are dynamic features of the cryosphere indicative of a changing climate. Spring melt and refreeze timing are of particular importance due to the influence on subsequent hydrological and ecological processes, including peak runoff and green-up. To investigate the spatial and temporal variability of melt timing across a sub-arctic region (the Yukon River Basin (YRB), Alaska/Canada) dominated by snow and lacking substantial ground instrumentation, passive microwave remote sensing was utilized to provide daily brightness temperatures (Tb) regardless of clouds and darkness. Algorithms to derive the timing of melt onset and the end of melt-refreeze, a critical transition period where the snowpack melts during the day and refreezes at night, were based on thresholds for Tb and diurnal amplitude variations (day and night difference). Tb data from the Special Sensor Microwave Imager (1988 to 2011) was used for analyzing YRB terrestrial snowmelt timing and for characterizing melt regime patterns for icefields in Alaska and Patagonia. Tb data from the Advanced Microwave Scanning Radiometer for EOS (2003 to 2010) was used for determining the occurrence of early melt events (before melt onset) associated with fog or rain on snow, for investigating the correlation between melt timing and forest fires, and for driving a flux-based snowmelt runoff model. From the SSM/I analysis: the melt-refreeze period lengthened for the majority of the YRB with later end of melt-refreeze and earlier melt onset; and positive Tb anomalies were found in recent years from glacier melt dynamics. From the AMSR-E analysis: early melt events throughout the YRB were most often associated with warm air intrusions and reflect a consistent spatial distribution; years and areas of earlier melt onset and refreeze had more forest fire occurrences suggesting melt timing's effects extend to later seasons; and satellite derived melt timing served as an effective input for model

  3. Documentation of a spatial data-base management system for monitoring pesticide application in Washington

    USGS Publications Warehouse

    Schurr, K.M.; Cox, S.E.

    1994-01-01

    The Pesticide-Application Data-Base Management System was created as a demonstration project and was tested with data submitted to the Washington State Department of Agriculture by pesticide applicators from a small geographic area. These data were entered into the Department's relational data-base system and uploaded into the system's ARC/INFO files. Locations for pesticide applica- tions are assigned within the Public Land Survey System grids, and ARC/INFO programs in the Pesticide-Application Data-Base Management System can subdivide each survey section into sixteen idealized quarter-quarter sections for display map grids. The system provides data retrieval and geographic information system plotting capabilities from a menu of seven basic retrieval options. Additionally, ARC/INFO coverages can be created from the retrieved data when required for particular applications. The Pesticide-Application Data-Base Management System, or the general principles used in the system, could be adapted to other applica- tions or to other states.

  4. Optimal steering for kinematic vehicles with applications to spatially distributed agents

    NASA Astrophysics Data System (ADS)

    Brown, Scott; Praeger, Cheryl E.; Giudici, Michael

    While there is no universal method to address control problems involving networks of autonomous vehicles, there exist a few promising schemes that apply to different specific classes of problems, which have attracted the attention of many researchers from different fields. In particular, one way to extend techniques that address problems involving a single autonomous vehicle to those involving teams of autonomous vehicles is to use the concept of Voronoi diagram. The Voronoi diagram provides a spatial partition of the environment the team of vehicles operate in, where each element of this partition is associated with a unique vehicle from the team. The partition induces a graph abstraction of the operating space that is in an one-to-one correspondence with the network abstraction of the team of autonomous vehicles; a fact that can provide both conceptual and analytical advantages during mission planning and execution. In this dissertation, we propose the use of a new class of Voronoi-like partitioning schemes with respect to state-dependent proximity (pseudo-) metrics rather than the Euclidean distance or other generalized distance functions, which are typically used in the literature. An important nuance here is that, in contrast to the Euclidean distance, state-dependent metrics can succinctly capture system theoretic features of each vehicle from the team (e.g., vehicle kinematics), as well as the environment-vehicle interactions, which are induced, for example, by local winds/currents. We subsequently illustrate how the proposed concept of state-dependent Voronoi-like partition can induce local control schemes for problems involving networks of spatially distributed autonomous vehicles by examining a sequential pursuit problem of a maneuvering target by a group of pursuers distributed in the plane. The construction of generalized Voronoi diagrams with respect to state-dependent metrics poses some significant challenges. First, the generalized distance metric

  5. Spatial, High-Accuracy, Positioning-Encoding Sensor (SHAPES) for large space system control applications

    NASA Technical Reports Server (NTRS)

    Mclauchlan, J. M.

    1982-01-01

    The Spatial, High-Accuracy, Position-Encoding Sensor is a controls sensor suitable for the determination of the static shape and vibrational motion of large space structures and similar systems and for the determination of position and velocity in rendezvous and docking. It uses a combination of electro-optical techniques to measure the three-dimensional coordinates distributed over the structure at reading rates high compared to the rates at which the coordinates are changing. The technical approach is that of measuring the distance to and the direction of points on the structure from a single sensor head. Many points can be measured simultaneously from a single head without significantly increasing the complexity of the system.

  6. Transmissive spatial light modulators with high figure-of-merit liquid crystals for foveated imaging applications

    NASA Astrophysics Data System (ADS)

    Harriman, Jamie; Gauza, Sebastian; Wu, Shin-Tson; Wick, David; Bagwell, Brett; Martinez, Ty; Payne, Don; Serati, Steven

    2006-02-01

    Unique liquid crystal (LC) spatial light modulators (SLM) are being developed for foveated imaging systems that provide wide field-of-view (FOV) coverage (+/-60° in azimuth and elevation) without requiring gimbals or other mechanical scanners. Recently, a transmissive-SLM- based system operating in the visible (532 nm) has been demonstrated. The LC SLM development is addressing implementation issues through the development of high figure-of-merit (FoM) LC materials and transmissive high-resolution SLMs. Transmissive SLM operation allows the foveated imaging configuration to be very compact using a very simple lens system. The reduction in the size, weight and cost of the imaging optics and in data acquisition/processing hardware makes the foveated approach attractive for small platforms such as unmanned airborne vehicles (UAVs) or missile seekers.

  7. Image segmentation using joint spatial-intensity-shape features: application to CT lung nodule segmentation

    NASA Astrophysics Data System (ADS)

    Ye, Xujiong; Siddique, Musib; Douiri, Abdel; Beddoe, Gareth; Slabaugh, Greg

    2009-02-01

    Automatic segmentation of medical images is a challenging problem due to the complexity and variability of human anatomy, poor contrast of the object being segmented, and noise resulting from the image acquisition process. This paper presents a novel feature-guided method for the segmentation of 3D medical lesions. The proposed algorithm combines 1) a volumetric shape feature (shape index) based on high-order partial derivatives; 2) mean shift clustering in a joint spatial-intensity-shape (JSIS) feature space; and 3) a modified expectation-maximization (MEM) algorithm on the mean shift mode map to merge the neighboring regions (modes). In such a scenario, the volumetric shape feature is integrated into the process of the segmentation algorithm. The joint spatial-intensity-shape features provide rich information for the segmentation of the anatomic structures or lesions (tumors). The proposed method has been evaluated on a clinical dataset of thoracic CT scans that contains 68 nodules. A volume overlap ratio between each segmented nodule and the ground truth annotation is calculated. Using the proposed method, the mean overlap ratio over all the nodules is 0.80. On visual inspection and using a quantitative evaluation, the experimental results demonstrate the potential of the proposed method. It can properly segment a variety of nodules including juxta-vascular and juxta-pleural nodules, which are challenging for conventional methods due to the high similarity of intensities between the nodules and their adjacent tissues. This approach could also be applied to lesion segmentation in other anatomies, such as polyps in the colon.

  8. Thermal Characterization of Defects in Aircraft Structures Via Spatially Controlled Heat Application

    NASA Technical Reports Server (NTRS)

    Cramer, K. Elliott; Winfree, William P.

    1997-01-01

    Recent advances in thermal imaging technology have spawned a number of new thermal NDE techniques that provide quantitative information about flaws in aircraft structures. Thermography has a number of advantages as an inspection technique. It is a totally noncontacting, nondestructive, imaging technology capable of inspecting a large area in a matter of a few seconds. The development of fast, inexpensive image processors have aided in the attractiveness of thermography as an NDE technique. These image processors have increased the signal to noise ratio of thermography and facilitated significant advances in post-processing. The resulting digital images enable archival records for comparison with later inspections thus providing a means of monitoring the evolution of damage in a particular structure. The National Aeronautics and Space Administration's Langley Research Center has developed a thermal NDE technique designed to image a number of potential flaws in aircraft structures. The technique involves injecting a small, spatially controlled heat flux into the outer surface of an aircraft. Images of fatigue cracking, bond integrity and material loss due to corrosion are generated from measurements of the induced surface temperature variations. This paper will present a discussion of the development of the thermal imaging system as well as the techniques used to analyze the resulting thermal images. Spatial tailoring of the heat coupled with the analysis techniques represent a significant improvement in the delectability of flaws over conventional thermal imaging. Results of laboratory experiments on fabricated crack, disbond and material loss samples will be presented to demonstrate the capabilities of the technique. An integral part of the development of this technology is the use of analytic and computational modeling. The experimental results will be compared with these models to demonstrate the utility of such an approach.

  9. Spatial deconvolution of spectropolarimetric data: an application to quiet Sun magnetic elements

    NASA Astrophysics Data System (ADS)

    Quintero Noda, C.; Asensio Ramos, A.; Orozco Suárez, D.; Ruiz Cobo, B.

    2015-07-01

    Context. One of the difficulties in extracting reliable information about the thermodynamical and magnetic properties of solar plasmas from spectropolarimetric observations is the presence of light dispersed inside the instruments, known as stray light. Aims: We aim to analyze quiet Sun observations after the spatial deconvolution of the data. We examine the validity of the deconvolution process with noisy data as we analyze the physical properties of quiet Sun magnetic elements. Methods: We used a regularization method that decouples the Stokes inversion from the deconvolution process, so that large maps can be quickly inverted without much additional computational burden. We applied the method on Hinode quiet Sun spectropolarimetric data. We examined the spatial and polarimetric properties of the deconvolved profiles, comparing them with the original data. After that, we inverted the Stokes profiles using the Stokes Inversion based on Response functions (SIR) code, which allow us to obtain the optical depth dependence of the atmospheric physical parameters. Results: The deconvolution process increases the contrast of continuum images and makes the magnetic structures sharper. The deconvolved Stokes I profiles reveal the presence of the Zeeman splitting while the Stokes V profiles significantly change their amplitude. The area and amplitude asymmetries of these profiles increase in absolute value after the deconvolution process. We inverted the original Stokes profiles from a magnetic element and found that the magnetic field intensity reproduces the overall behavior of theoretical magnetic flux tubes, that is, the magnetic field lines are vertical in the center of the structure and start to fan when we move far away from the center of the magnetic element. The magnetic field vector inferred from the deconvolved Stokes profiles also mimic a magnetic flux tube but in this case we found stronger field strengths and the gradients along the line-of-sight are larger

  10. Spatial organization of cilia tufts governs airways mucus transport: Application to severe asthma

    NASA Astrophysics Data System (ADS)

    Khelloufi, Mustapha Kamel; Gras, Delphine; Chanez, Pascal; Viallat, Annie

    2014-11-01

    We study the coupling between both density and spatial repartition of beating cilia tufts, and the coordinated transport of mucus in an in-vitro epithelial model. We use a fully differentiated model epithelium in air liquid interface (ALI) obtained from endo-bronchial biopsies from healthy subjects and patients with asthma. The asthma phenotype is known to persist in the model. Mucus transport is characterized by the trajectories and velocities of microscopic beads incorporated in the mucus layer. When the beating cilia tufts density is higher than dc = 11/100 × 100 μm2 a spherical spiral coordinated mucus transport is observed over the whole ALI chamber (radius = 6 mm). Below dc, local mucus coordinated transport is observed on small circular domains on the epithelium surface. We reveal that the radii of these domains scale with the beating cilia tufts density with a power 3.7. Surprisingly, this power law is independent on cilia beat frequency, concentration and rheological properties of mucus for healthy subject and patient with asthma. The rotating or linear mucus transport is related to dispersion of the cilia tufts on the epithelium surface. We show that impaired mucus transport observed in severe asthma model epithelia is due to a drastic lack and dysfunction of cilia tufts. The author acknowledges the support of the French Agence Nationale de la Recherche (ANR) under reference ANR-13-BSV5-0015-01.

  11. Spatial filtering self-velocimeter for vehicle application using a CMOS linear image sensor

    NASA Astrophysics Data System (ADS)

    He, Xin; Zhou, Jian; Nie, Xiaoming; Long, Xingwu

    2015-03-01

    The idea of using a spatial filtering velocimeter (SFV) to measure the velocity of a vehicle for an inertial navigation system is put forward. The presented SFV is based on a CMOS linear image sensor with a high-speed data rate, large pixel size, and built-in timing generator. These advantages make the image sensor suitable to measure vehicle velocity. The power spectrum of the output signal is obtained by fast Fourier transform and is corrected by a frequency spectrum correction algorithm. This velocimeter was used to measure the velocity of a conveyor belt driven by a rotary table and the measurement uncertainty is ˜0.54%. Furthermore, it was also installed on a vehicle together with a laser Doppler velocimeter (LDV) to measure self-velocity. The measurement result of the designed SFV is compared with that of the LDV. It is shown that the measurement result of the SFV is coincident with that of the LDV. Therefore, the designed SFV is suitable for a vehicle self-contained inertial navigation system.

  12. Spatial Temporal Image Correlation Spectroscopy (STICS) for Flow Analysis with Application for Blood Flow Mapping

    SciTech Connect

    Rossow, Molly; Gratton, Enrico; Mantulin, William M.

    2009-04-19

    It is important for surgeons to be able to measure blood flow in exposed arterioles during surgery. We report our progress in the development of an optical technique that will measure blood flow in surgically exposed blood vessels and enable previously difficult measurements. By monitoring optical fluctuations, the optical technique, based on Spatial Temporal Image Correlation (STICS), will directly measure the velocity of micron-scale particles--such as red blood cells. It will complement existing technology and provide qualitative measurements that were not previously possible. It relies on the concept that blood, when viewed on a small enough scale, is an inhomogeneous substance. Individual blood cells passing between a near-infrared light source and a detector will cause fluctuations in the transmitted optical signal. The speed, direction, and flow pattern of blood cells can be determined from these optical fluctuations. We present a series of computer simulations and experiments on phantom and animal systems to test this technique's ability to map complex flow patterns.

  13. Michaelis-Menten Kinetics under Spatially Constrained Conditions: Application to Mibefradil Pharmacokinetics

    PubMed Central

    Kosmidis, Kosmas; Karalis, Vangelis; Argyrakis, Panos; Macheras, Panos

    2004-01-01

    Two different approaches were used to study the kinetics of the enzymatic reaction under heterogeneous conditions to interpret the unusual nonlinear pharmacokinetics of mibefradil. Firstly, a detailed model based on the kinetic differential equations is proposed to study the enzymatic reaction under spatial constraints and in vivo conditions. Secondly, Monte Carlo simulations of the enzyme reaction in a two-dimensional square lattice, placing special emphasis on the input and output of the substrate were applied to mimic in vivo conditions. Both the mathematical model and the Monte Carlo simulations for the enzymatic reaction reproduced the classical Michaelis-Menten (MM) kinetics in homogeneous media and unusual kinetics in fractal media. Based on these findings, a time-dependent version of the classic MM equation was developed for the rate of change of the substrate concentration in disordered media and was successfully used to describe the experimental plasma concentration-time data of mibefradil and derive estimates for the model parameters. The unusual nonlinear pharmacokinetics of mibefradil originates from the heterogeneous conditions in the reaction space of the enzymatic reaction. The modified MM equation can describe the pharmacokinetics of mibefradil as it is able to capture the heterogeneity of the enzymatic reaction in disordered media. PMID:15345531

  14. Spatial Temporal Image Correlation Spectroscopy (STICS) for Flow Analysis with Application for Blood Flow Mapping (abstract)

    NASA Astrophysics Data System (ADS)

    Rossow, Molly; Mantulin, William M.; Gratton, Enrico

    2009-04-01

    It is important for surgeons to be able to measure blood flow in exposed arterioles during surgery. We report our progress in the development of an optical technique that will measure blood flow in surgically exposed blood vessels and enable previously difficult measurements. By monitoring optical fluctuations, the optical technique, based on Spatial Temporal Image Correlation (STICS), will directly measure the velocity of micron-scale particles-such as red blood cells. It will complement existing technology and provide qualitative measurements that were not previously possible. It relies on the concept that blood, when viewed on a small enough scale, is an inhomogeneous substance. Individual blood cells passing between a near-infrared light source and a detector will cause fluctuations in the transmitted optical signal. The speed, direction, and flow pattern of blood cells can be determined from these optical fluctuations. We present a series of computer simulations and experiments on phantom and animal systems to test this technique's ability to map complex flow patterns.

  15. Patch-Based Segmentation with Spatial Consistency: Application to MS Lesions in Brain MRI

    PubMed Central

    Mechrez, Roey; Goldberger, Jacob; Greenspan, Hayit

    2016-01-01

    This paper presents an automatic lesion segmentation method based on similarities between multichannel patches. A patch database is built using training images for which the label maps are known. For each patch in the testing image, k similar patches are retrieved from the database. The matching labels for these k patches are then combined to produce an initial segmentation map for the test case. Finally an iterative patch-based label refinement process based on the initial segmentation map is performed to ensure the spatial consistency of the detected lesions. The method was evaluated in experiments on multiple sclerosis (MS) lesion segmentation in magnetic resonance images (MRI) of the brain. An evaluation was done for each image in the MICCAI 2008 MS lesion segmentation challenge. Results are shown to compete with the state of the art in the challenge. We conclude that the proposed algorithm for segmentation of lesions provides a promising new approach for local segmentation and global detection in medical images. PMID:26904103

  16. Spatial Variability and Application of Ratios between BTEX in Two Canadian Cities

    PubMed Central

    Miller, Lindsay; Xu, Xiaohong; Wheeler, Amanda; Atari, Dominic Odwa; Grgicak-Mannion, Alice; Luginaah, Isaac

    2011-01-01

    Spatial monitoring campaigns of volatile organic compounds were carried out in two similarly sized urban industrial cities, Windsor and Sarnia, ON, Canada. For Windsor, data were obtained for all four seasons at approximately 50 sites in each season (winter, spring, summer, and fall) over a three-year period (2004, 2005, and 2006) for a total of 12 sampling sessions. Sampling in Sarnia took place at 37 monitoring sites in fall 2005. In both cities, passive sampling was done using 3M 3500 organic vapor samplers. This paper characterizes benzene, toluene, ethylbenzene, o, and (m + p)-xylene (BTEX) concentrations and relationships among BTEX species in the two cities during the fall sampling periods. BTEX concentration levels and rank order among the species were similar between the two cities. In Sarnia, the relationships between the BTEX species varied depending on location. Correlation analysis between land use and concentration ratios showed a strong influence from local industries. Use one of the ratios between the BTEX species to diagnose photochemical age may be biased due to point source emissions, for example, 53 tonnes of benzene and 86 tonnes of toluene in Sarnia. However, considering multiple ratios leads to better conclusions regarding photochemical aging. Ratios obtained in the sampling campaigns showed significant deviation from those obtained at central monitoring stations, with less difference in the (m + p)/E ratio but better overall agreement in Windsor than in Sarnia. PMID:22235184

  17. Application of speed-enhanced spatial domain correlation filters for real-time security monitoring

    NASA Astrophysics Data System (ADS)

    Gardezi, Akber; Bangalore, Nagachetan; Al-Kandri, Ahmed; Birch, Philip; Young, Rupert; Chatwin, Chris

    2011-11-01

    A speed enhanced space variant correlation filer which has been designed to be invariant to change in orientation and scale of the target object but also to be spatially variant, i.e. the filter function becoming dependant on local clutter conditions within the image. The speed enhancement of the filter is due to the use of optimization techniques employing low-pass filtering to restrict kernel movement to be within regions of interest. The detection and subsequent identification capability of the two-stage process has been evaluated in highly cluttered backgrounds using both visible and thermal imagery acquired from civil and defense domains along with associated training data sets for target detection and classification. In this paper a series of tests have been conducted in multiple scenarios relating to situations that pose a security threat. Performance matrices comprised of peak-to-correlation energy (PCE) and peak-to-side lobe ratio (PSR) measurements of the correlation output have been calculated to allow the definition of a recognition criterion. The hardware implementation of the system has been discussed in terms of Field Programmable Gate Array (FPGA) chipsets with implementation bottle necks and their solution being considered.

  18. Application of high spatial resolution airborne hyperspectral remote sensing data in thematic information extraction

    NASA Astrophysics Data System (ADS)

    Xu, Hong-gen; Ma, Hong-chao; Li, De-ren; Song, Yan

    2006-10-01

    The airborne hyperspectral remote sensing data, such as PHI, OMIS, has the virtues of high spatial and spectral resolution. Hence, from the view of target classification we can consider that it can provide the ability of discriminating targets more detailedly than other data. So it's important to extract thematic information and update database using this kind of data. Whereas, the hyperspectral data has abundant bands and high between-band correlation, the traditional classification methods such as maximum likelihood classifier (MLC) and spectral angle mapper (SAM) have performed poorly in thematic information extraction. For this reason, we present a new method for thematic information extraction with hyperspectral remote sensing data. We perform classification by means of combining the self-organizing map (SOM) neural network which is considered as full-pixel technique with linear spectral mixture analysis (LSMA) which is considered as mixed-pixel technique. The SOM neural network is improved from some aspects to classify the pure data and find the mixed data. And then the mixed data are unmixed and classified by LSMA. The result of experiment shows that we can have the better performance in thematic information extraction with PHI by this means.

  19. Laser correlation velocimetry performance in diesel applications: spatial selectivity and velocity sensitivity

    NASA Astrophysics Data System (ADS)

    Hespel, Camille; Blaisot, Jean-Bernard; Gazon, Matthieu; Godard, Gilles

    2012-07-01

    The characterization of diesel jets in the near field of the nozzle exit still presents challenges for experimenters. Detailed velocity measurements are needed to characterize diesel injector performance and also to establish boundary conditions for CFD codes. The present article examines the efficiency of laser correlation velocimetry (LCV) applied to diesel spray characterization. A new optical configuration based on a long-distance microscope was tested, and special care was taken to examine the spatial selectivity of the technique. Results show that the depth of the measurement volume (along the laser beam) of LCV extends beyond the depth of field of the imaging setup. The LCV results were also found to be particularly sensitive to high-speed elements of a spray. Results from high-pressure diesel jets in a back-pressure environment indicate that this technique is particularly suited to the very near field of the nozzle exit, where the flow is the narrowest and where the velocity distribution is not too large. It is also shown that the performance of the LCV technique is controlled by the filtering and windowing parameters used in the processing of the raw signals.

  20. Application of a computable model of human spatial vision to phase discrimination

    NASA Technical Reports Server (NTRS)

    Nielsen, K. R. K.; Watson, A. B.; Ahumada, A. J., Jr.

    1985-01-01

    A computable model of human spatial vision is used to make predictions for phase-discrimination experiments. This model is being developed to deal with a broad range of problems in vision and was not specifically formulated to deal with phase discrimination. In the model, cross-correlation of the stimuli with an array of sensors produces feature vectors that are operated on by a position-uncertain ideal observer to simulate detection and discrimination experiments. In this report, the stimuli are compound sinusoidal gratings composed of a fundamental and a higher-frequency component added in various phases. Model predictions are compared with three key results from the literature: (1) the effect of the contrast of the fundamental on phase discrimination, (2) threshold phase difference as a function of the fundamental frequency, and (3) the contrast required for phase discrimination as a function of the frequency ratio of the two grating components. In the first two cases, the predictions capture the main features of the data, although quantitative discrepancies remain. In the third case, the model fails, and this failure suggests additional restrictions on the combination of information across sensors.

  1. Mapping Genetic Diversity of Cherimoya (Annona cherimola Mill.): Application of Spatial Analysis for Conservation and Use of Plant Genetic Resources

    PubMed Central

    van Zonneveld, Maarten; Scheldeman, Xavier; Escribano, Pilar; Viruel, María A.; Van Damme, Patrick; Garcia, Willman; Tapia, César; Romero, José; Sigueñas, Manuel; Hormaza, José I.

    2012-01-01

    There is a growing call for inventories that evaluate geographic patterns in diversity of plant genetic resources maintained on farm and in species' natural populations in order to enhance their use and conservation. Such evaluations are relevant for useful tropical and subtropical tree species, as many of these species are still undomesticated, or in incipient stages of domestication and local populations can offer yet-unknown traits of high value to further domestication. For many outcrossing species, such as most trees, inbreeding depression can be an issue, and genetic diversity is important to sustain local production. Diversity is also crucial for species to adapt to environmental changes. This paper explores the possibilities of incorporating molecular marker data into Geographic Information Systems (GIS) to allow visualization and better understanding of spatial patterns of genetic diversity as a key input to optimize conservation and use of plant genetic resources, based on a case study of cherimoya (Annona cherimola Mill.), a Neotropical fruit tree species. We present spatial analyses to (1) improve the understanding of spatial distribution of genetic diversity of cherimoya natural stands and cultivated trees in Ecuador, Bolivia and Peru based on microsatellite molecular markers (SSRs); and (2) formulate optimal conservation strategies by revealing priority areas for in situ conservation, and identifying existing diversity gaps in ex situ collections. We found high levels of allelic richness, locally common alleles and expected heterozygosity in cherimoya's putative centre of origin, southern Ecuador and northern Peru, whereas levels of diversity in southern Peru and especially in Bolivia were significantly lower. The application of GIS on a large microsatellite dataset allows a more detailed prioritization of areas for in situ conservation and targeted collection across the Andean distribution range of cherimoya than previous studies could do, i.e. at

  2. Mapping genetic diversity of cherimoya (Annona cherimola Mill.): application of spatial analysis for conservation and use of plant genetic resources.

    PubMed

    Zonneveld, Maarten van; Scheldeman, Xavier; Escribano, Pilar; Viruel, María A; Van Damme, Patrick; Garcia, Willman; Tapia, César; Romero, José; Sigueñas, Manuel; Hormaza, José I

    2012-01-01

    There is a growing call for inventories that evaluate geographic patterns in diversity of plant genetic resources maintained on farm and in species' natural populations in order to enhance their use and conservation. Such evaluations are relevant for useful tropical and subtropical tree species, as many of these species are still undomesticated, or in incipient stages of domestication and local populations can offer yet-unknown traits of high value to further domestication. For many outcrossing species, such as most trees, inbreeding depression can be an issue, and genetic diversity is important to sustain local production. Diversity is also crucial for species to adapt to environmental changes. This paper explores the possibilities of incorporating molecular marker data into Geographic Information Systems (GIS) to allow visualization and better understanding of spatial patterns of genetic diversity as a key input to optimize conservation and use of plant genetic resources, based on a case study of cherimoya (Annona cherimola Mill.), a Neotropical fruit tree species. We present spatial analyses to (1) improve the understanding of spatial distribution of genetic diversity of cherimoya natural stands and cultivated trees in Ecuador, Bolivia and Peru based on microsatellite molecular markers (SSRs); and (2) formulate optimal conservation strategies by revealing priority areas for in situ conservation, and identifying existing diversity gaps in ex situ collections. We found high levels of allelic richness, locally common alleles and expected heterozygosity in cherimoya's putative centre of origin, southern Ecuador and northern Peru, whereas levels of diversity in southern Peru and especially in Bolivia were significantly lower. The application of GIS on a large microsatellite dataset allows a more detailed prioritization of areas for in situ conservation and targeted collection across the Andean distribution range of cherimoya than previous studies could do, i.e. at

  3. Spatial Heat Maps from Fast Information Matching of Fast and Slow Degrees of Freedom: Application to Molecular Dynamics Simulations.

    PubMed

    Kovacs, Julio A; Wriggers, Willy

    2016-08-25

    We introduce a fast information matching (FIM) method for transforming time domain data into spatial images through handshaking between fast and slow degrees of freedom. The analytics takes advantage of the detailed time series available from biomolecular computer simulations, and it yields spatial heat maps that can be visualized on 3D molecular structures or in the form of interaction networks. The speed of our efficient mutual information solver is on the order of a basic Pearson cross-correlation calculation. We demonstrate that the FIM method is superior to linear cross-correlation for the detection of nonlinear dependence in challenging situations where measures for the global dynamics (the "activity") diverge. The analytics is applied to the detection of hinge-bending hot spots and to the prediction of pairwise contacts between residues that are relevant for the global activity exhibited by the molecular dynamics (MD) trajectories. Application examples from various MD laboratories include the millisecond bovine pancreatic trypsin inhibitor (BPTI) trajectory using canonical MD, a Gaussian accelerated MD folding trajectory of chignolin, and the heat-induced unfolding of engrailed homeodomain (EnHD). The FIM implementation will be freely disseminated with our open-source package, TimeScapes. PMID:27169521

  4. Spatial Techniques

    NASA Astrophysics Data System (ADS)

    Jabeur, Nafaa; Sahli, Nabil

    The environment, including the Earth and the immense space, is recognized to be the main source of useful information for human beings. During several decades, the acquisition of data from this environment was constrained by tools and techniques with limited capabilities. However, thanks to continuous technological advances,spatial data are available in huge quantities for different applications. The technological advances have been achieved in terms of hardware and software as well. They are allowing for better accuracy and availability, which in turn improves the quality and quantity of useful knowledge that can be extracted from the environment. They have been applied to geography, resulting in geospatial techniques. Applied to both science and technology, geospatial techniques resulted in areas of expertise, such as land surveying, cartography, navigation, remote sensing, Geographic Infor-mation Systems (GISs), and Global Positioning Systems (GPSs). They had evolved quickly with advances in computing, satellite technology and a growing demand to understand our global environment. In this chapter, we will discuss three important techniques that are widely used in spatial data acquisition and analysis: GPS and remote sensing techniques that are used to collect spatial data and a GIS that is used to store, manipulate, analyze, and visualize spatial data. Later in this book, we will discuss the techniques that are currently available for spatial knowledge discovery.

  5. Development of a web GIS application for emissions inventory spatial allocation based on open source software tools

    NASA Astrophysics Data System (ADS)

    Gkatzoflias, Dimitrios; Mellios, Giorgos; Samaras, Zissis

    2013-03-01

    Combining emission inventory methods and geographic information systems (GIS) remains a key issue for environmental modelling and management purposes. This paper examines the development of a web GIS application as part of an emission inventory system that produces maps and files with spatial allocated emissions in a grid format. The study is not confined in the maps produced but also presents the features and capabilities of a web application that can be used by every user even without any prior knowledge of the GIS field. The development of the application was based on open source software tools such as MapServer for the GIS functions, PostgreSQL and PostGIS for the data management and HTML, PHP and JavaScript as programming languages. In addition, background processes are used in an innovative manner to handle the time consuming and computational costly procedures of the application. Furthermore, a web map service was created to provide maps to other clients such as the Google Maps API v3 that is used as part of the user interface. The output of the application includes maps in vector and raster format, maps with temporal resolution on daily and hourly basis, grid files that can be used by air quality management systems and grid files consistent with the European Monitoring and Evaluation Programme Grid. Although the system was developed and validated for the Republic of Cyprus covering a remarkable wide range of pollutant and emissions sources, it can be easily customized for use in other countries or smaller areas, as long as geospatial and activity data are available.

  6. Teledetection passive et processus decisionnel a reference spatiale: Application a l'aquaculture en milieu marin

    NASA Astrophysics Data System (ADS)

    Habbane, Mohamed

    L'objectif de cette etude est d'elaborer un processus decisionnel a reference spatiale (PDRS) pour la mariculture. Le PDRS est applique aux eaux cotieres de la baie des Chaleurs, dans le golfe du Saint-Laurent (Canada). Une carte preliminaire regionale d'indices du potentiel maricole, d'une limite de resolution spatiale de 1 kmsp2, est produite avec des parametres du niveau 1. Ces parametres englobent la temperature de l'eau de surface, extraite des images AVHRR, la salinite, les courants ainsi que les pigments chlorophylliens, quantifies a l'aide de mesures in situ. Les images AVHRR, prises en 1994, ont ete utiliees comme reference primaire pour selectionner des aires pouvant supporter une activite maricole sur la cote nord de la baie des Chaleurs. La temperature de surface extraite de ces images permet une analyse mesoechelle a la fois qualitative et quantitative des processus cotiers observes pendant la periode d'acquisition des donnees. Les autres donnees, soit la salinite, les courants et les concentrations en pigments chlorophylliens, sont analysees de facon a identifier la variabilite spatio-temporelle des caracteristiques des eaux de surface. L'ensemble des informations permet de produire une carte preliminaire regionale d'indices du potentiel maricole de la partie centrale de la baie des Chaleurs. Selon cet indice (defini entre 0 et 1), le secteur de potentiel aquicole de 0,5 a 0,75 s'etend sur une superficie d'environ 300 kmsp2. La localisation de cette aire potentielle est en accord avec les fortes concentrations en pigments chlrophylliens, presentant des conditions environnementales ideales a une haute productivite biologique. Par la suite la carte preliminaire est modifiee en tenant compte des parametres du niveau 2. Ces parametres sont la geomorphologie littorale, la bathymetrie, les sediments en suspension, les vents, les vagues, le debit d'eau douce, la glace marine, le carbone organique dissous, les aires de peche et les sources de pollution. Ces

  7. Spatial Frequency Domain Imaging: Applications in Preclinical Models of Alzheimer's Disease

    NASA Astrophysics Data System (ADS)

    Lin, Alexander Justin

    A clinical challenge in Alzheimer's disease (AD) is diagnosing and treating patients earlier, before symptoms of cognitive dysfunction occur. A good screening test would be sensitive to the AD brain pathology, safe, and cost-effective. Diffuse optical imaging, which measures how non-ionizing light is absorbed and scattered in tissue, may fulfill these three parameters. We imaged the brains of transgenic AD mouse models in vivo with a quantitative, camera-based, diffuse optical imaging technology called spatial frequency domain imaging (SFDI) to characterize near-infrared (650-970nm) optical biomarkers of AD. Compared to age-matched control mice, we found a decrease in light absorption --- due to lower oxygenated and total hemoglobin concentrations in the brain --- correlating to decreased blood vessel volume and density in histology. Light scattering also increased in AD mice, correlating to brain structural changes caused by neuron loss and activation of inflammatory cells. Furthermore, inhaled gas challenges revealed brain vascular function was diminished. To investigate how AD affects the small changes in blood perfusion caused by increased brain activity, we built a new SFDI system from a commercial light-emitting diode microprojector and off-the-shelf optical components and cameras to measure optical properties in the visible range (460-632nm). Our measurements showed a reduced amplitude and duration of blood vessel dilation to increased brain activity in the AD mice. Altogether, this work increased our understanding of AD pathogenesis, explored optical biomarkers of AD, and improved technology access to other research labs. These results and technologies can further be used to facilitate longitudinal drug therapy trials in mice and provide a roadmap to diffuse optical spectroscopy studies in humans.

  8. Frequency assessment of spatially distributed generations of flood scenarios: an application on Italian territory

    NASA Astrophysics Data System (ADS)

    Lomazzi, M.; Roth, G.; Rudari, R.; Taramasso, A. C.; Ghizzoni, T.; Benedetti, R.; Espa, G.; Terpessi, C.

    2009-12-01

    The flooding risk impact on society cannot be understated: it influences land use and territorial planning and development at both physical and regulatory levels. To cope with it, a variety of actions can be put in place, involving multidisciplinary competences. Mitigation measures goes from the improvement of monitoring systems to the development of hydraulic structures, throughout land use restrictions, civil protection and insurance plans. All of those options present social and economic impacts, either positive or negative, whose proper estimate should rely on the assumption of appropriate - present and future - scenarios, i.e. quantitative event descriptions in terms of i) the flood hazard, with its probability of occurrence, extension, intensity, and duration, ii) the exposed values and iii) their vulnerability. At present, initial attention has been devoted to the design of flood scenarios, or ensembles of them, and to the evaluation of their frequency of occurrence. In the present work, a model for spatially distributed flood scenarios generation and frequency assessment is proposed and applied to the Italian territory. The study area has been divided into homogeneous regions according to their hydrologic, orographic and meteoclimatic characteristics. A statistical model for flood scenarios simulation has been implemented throughout a conditional approach based on MCMC simulations by using i) a historical flood events catalogue; ii) a homogeneous regions correlation matrix; and iii) an auxiliary variables data set. In this framework, the role of the information stored in the historical flood events catalogue "Aree Vulnerate Italiane" (AVI, http://avi.gndci.cnr.it/), produced by the Italian National Research Council, is of crucial importance.

  9. The Application of Spatial Signature Analysis to Electrical Test Data: Validation Study

    SciTech Connect

    Gleason, S.S.; Karnowski, T.P.; Lakhani, F.; Tobin, K.W.

    1999-03-15

    This paper presents the results of the Spatial Signature Analysis (SSA) Electrical-test (e-test) validation study that was conducted between February and June, 1998. SSA is an automated procedure developed by researchers at the Oak Ridge National Laboratory to address the issue of intelligent data reduction while providing feedback on current manufacturing processes. SSA was initially developed to automate the analysis of optical defect data. Optical defects can form groups, or clusters, which may have a distinct shape. These patterns can reveal information about the manufacturing process. Optical defect SSA uses image processing algorithms and a classifier system to interpret and identify these patterns, or signatures. SSA has been extended to analyze and interpret electrical test data. The algorithms used for optical defect SSA have been adapted and applied to e-test binmaps. An image of the binmap is created, and features such as geometric and invariant moments are extracted and presented to a pair-wise, fuzzy, k-NN classifier. The classifier itself was prepared by manually training, which consists of storing example signatures of interest in a library, then executing an automated process which treats the examples as prototype signatures. The training process includes a procedure for automatically determining which features are most relevant to each class. The evaluation was performed by installing the SSA software as a batch process at three SEMATECH member company sites. Feedback from member company representatives was incorporated and classifiers were built to automatically assign labels to the binmap signatures. The three sites produced memory devices (DRAM) and microprocessors in a mature process fabrication environment. For all of these products, 5,620 signatures that encompassed approximately 552 wafers were human-classified and analyzed. The performance of the SSA E-test system indicates that the approach was successful in reliably classifying binmap

  10. Application of spatial and non-spatial data analysis in determination of the factors that impact municipal solid waste generation rates in Turkey

    SciTech Connect

    Keser, Saniye; Duzgun, Sebnem; Aksoy, Aysegul

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Spatial autocorrelation exists in municipal solid waste generation rates for different provinces in Turkey. Black-Right-Pointing-Pointer Traditional non-spatial regression models may not provide sufficient information for better solid waste management. Black-Right-Pointing-Pointer Unemployment rate is a global variable that significantly impacts the waste generation rates in Turkey. Black-Right-Pointing-Pointer Significances of global parameters may diminish at local scale for some provinces. Black-Right-Pointing-Pointer GWR model can be used to create clusters of cities for solid waste management. - Abstract: In studies focusing on the factors that impact solid waste generation habits and rates, the potential spatial dependency in solid waste generation data is not considered in relating the waste generation rates to its determinants. In this study, spatial dependency is taken into account in determination of the significant socio-economic and climatic factors that may be of importance for the municipal solid waste (MSW) generation rates in different provinces of Turkey. Simultaneous spatial autoregression (SAR) and geographically weighted regression (GWR) models are used for the spatial data analyses. Similar to ordinary least squares regression (OLSR), regression coefficients are global in SAR model. In other words, the effect of a given independent variable on a dependent variable is valid for the whole country. Unlike OLSR or SAR, GWR reveals the local impact of a given factor (or independent variable) on the waste generation rates of different provinces. Results show that provinces within closer neighborhoods have similar MSW generation rates. On the other hand, this spatial autocorrelation is not very high for the exploratory variables considered in the study. OLSR and SAR models have similar regression coefficients. GWR is useful to indicate the local determinants of MSW generation rates. GWR model can be utilized to

  11. Applications of high-resolution spatial discretization scheme and Jacobian-free Newton–Krylov method in two-phase flow problems

    SciTech Connect

    Zou, Ling; Zhao, Haihua; Zhang, Hongbin

    2015-09-01

    The majority of the existing reactor system analysis codes were developed using low-order numerical schemes in both space and time. In many nuclear thermal–hydraulics applications, it is desirable to use higher-order numerical schemes to reduce numerical errors. High-resolution spatial discretization schemes provide high order spatial accuracy in smooth regions and capture sharp spatial discontinuity without nonphysical spatial oscillations. In this work, we adapted an existing high-resolution spatial discretization scheme on staggered grids in two-phase flow applications. Fully implicit time integration schemes were also implemented to reduce numerical errors from operator-splitting types of time integration schemes. The resulting nonlinear system has been successfully solved using the Jacobian-free Newton–Krylov (JFNK) method. The high-resolution spatial discretization and high-order fully implicit time integration numerical schemes were tested and numerically verified for several two-phase test problems, including a two-phase advection problem, a two-phase advection with phase appearance/disappearance problem, and the water faucet problem. Numerical results clearly demonstrated the advantages of using such high-resolution spatial and high-order temporal numerical schemes to significantly reduce numerical diffusion and therefore improve accuracy. Our study also demonstrated that the JFNK method is stable and robust in solving two-phase flow problems, even when phase appearance/disappearance exists.

  12. Application of spatial and non-spatial data analysis in determination of the factors that impact municipal solid waste generation rates in Turkey.

    PubMed

    Keser, Saniye; Duzgun, Sebnem; Aksoy, Aysegul

    2012-03-01

    In studies focusing on the factors that impact solid waste generation habits and rates, the potential spatial dependency in solid waste generation data is not considered in relating the waste generation rates to its determinants. In this study, spatial dependency is taken into account in determination of the significant socio-economic and climatic factors that may be of importance for the municipal solid waste (MSW) generation rates in different provinces of Turkey. Simultaneous spatial autoregression (SAR) and geographically weighted regression (GWR) models are used for the spatial data analyses. Similar to ordinary least squares regression (OLSR), regression coefficients are global in SAR model. In other words, the effect of a given independent variable on a dependent variable is valid for the whole country. Unlike OLSR or SAR, GWR reveals the local impact of a given factor (or independent variable) on the waste generation rates of different provinces. Results show that provinces within closer neighborhoods have similar MSW generation rates. On the other hand, this spatial autocorrelation is not very high for the exploratory variables considered in the study. OLSR and SAR models have similar regression coefficients. GWR is useful to indicate the local determinants of MSW generation rates. GWR model can be utilized to plan waste management activities at local scale including waste minimization, collection, treatment, and disposal. At global scale, the MSW generation rates in Turkey are significantly related to unemployment rate and asphalt-paved roads ratio. Yet, significances of these variables may diminish at local scale for some provinces. At local scale, different factors may be important in affecting MSW generation rates. PMID:22104614

  13. Optimising the application of multiple-capture traps for invasive species management using spatial simulation.

    PubMed

    Warburton, Bruce; Gormley, Andrew M

    2015-01-01

    Internationally, invasive vertebrate species pose a significant threat to biodiversity, agricultural production and human health. To manage these species a wide range of tools, including traps, are used. In New Zealand, brushtail possums (Trichosurus vulpecula), stoats (Mustela ermine), and ship rats (Rattus rattus) are invasive and there is an ongoing demand for cost-effective non-toxic methods for controlling these pests. Recently, traps with multiple-capture capability have been developed which, because they do not require regular operator-checking, are purported to be more cost-effective than traditional single-capture traps. However, when pest populations are being maintained at low densities (as is typical of orchestrated pest management programmes) it remains uncertain if it is more cost-effective to use fewer multiple-capture traps or more single-capture traps. To address this uncertainty, we used an individual-based spatially explicit modelling approach to determine the likely maximum animal-captures per trap, given stated pest densities and defined times traps are left between checks. In the simulation, single- or multiple-capture traps were spaced according to best practice pest-control guidelines. For possums with maintenance densities set at the lowest level (i.e. 0.5/ha), 98% of all simulated possums were captured with only a single capacity trap set at each site. When possum density was increased to moderate levels of 3/ha, having a capacity of three captures per trap caught 97% of all simulated possums. Results were similar for stoats, although only two potential captures per site were sufficient to capture 99% of simulated stoats. For rats, which were simulated at their typically higher densities, even a six-capture capacity per trap site only resulted in 80% kill. Depending on target species, prevailing density and extent of immigration, the most cost-effective strategy for pest control in New Zealand might be to deploy several single

  14. Optimising the Application of Multiple-Capture Traps for Invasive Species Management Using Spatial Simulation

    PubMed Central

    Warburton, Bruce; Gormley, Andrew M.

    2015-01-01

    Internationally, invasive vertebrate species pose a significant threat to biodiversity, agricultural production and human health. To manage these species a wide range of tools, including traps, are used. In New Zealand, brushtail possums (Trichosurus vulpecula), stoats (Mustela ermine), and ship rats (Rattus rattus) are invasive and there is an ongoing demand for cost-effective non-toxic methods for controlling these pests. Recently, traps with multiple-capture capability have been developed which, because they do not require regular operator-checking, are purported to be more cost-effective than traditional single-capture traps. However, when pest populations are being maintained at low densities (as is typical of orchestrated pest management programmes) it remains uncertain if it is more cost-effective to use fewer multiple-capture traps or more single-capture traps. To address this uncertainty, we used an individual-based spatially explicit modelling approach to determine the likely maximum animal-captures per trap, given stated pest densities and defined times traps are left between checks. In the simulation, single- or multiple-capture traps were spaced according to best practice pest-control guidelines. For possums with maintenance densities set at the lowest level (i.e. 0.5/ha), 98% of all simulated possums were captured with only a single capacity trap set at each site. When possum density was increased to moderate levels of 3/ha, having a capacity of three captures per trap caught 97% of all simulated possums. Results were similar for stoats, although only two potential captures per site were sufficient to capture 99% of simulated stoats. For rats, which were simulated at their typically higher densities, even a six-capture capacity per trap site only resulted in 80% kill. Depending on target species, prevailing density and extent of immigration, the most cost-effective strategy for pest control in New Zealand might be to deploy several single

  15. Models for assessing the spatial distribution of geodetic point patterns: application to geoid prediction quality

    NASA Astrophysics Data System (ADS)

    Hassouna, Raaed Mohamed Kamel

    2013-05-01

    In this study, some stochastic and deterministic models have been proposed for the assessment of the regularity and isotropy of geodetic point patterns. These models utilized realized point configurations within a rectangular window, leaning on stochastic geometry. As an illustrative example, the geographical extent of the Egyptian Territory was selected as a test window. The proposed models have agreed with the visual and qualitative characteristics of the investigated patterns. Also, it has been found that the stochastic and deterministic models for regularity and isotropy have very strong mutual correlation coefficients. Furthermore, the proposed models were applied to some geoid interpolation algorithms. In particular, the relationships among the data/check point distributions and the geoid interpolation accuracies, were investigated. Finally, a closed expression was proposed, which efficiently describes the relations among such features. So, it is recommended to use such approach for the pre-analysis and planning of the geographic distributions of point patterns in similar and other geodetic applications.

  16. Effect of spatial heterogeneities of water fluxes and application pattern on cadusafos fate on banana-cultivated andosols.

    PubMed

    Saison, C; Cattan, P; Louchart, X; Voltz, M

    2008-12-24

    In tropical humid environments under intensive banana production, pesticide transfer in waters can be of particular concern due to heavy rainfall, steep slopes, and soils with high infiltration capacities. The transfer in percolation and runoff waters of the nematicide cadusafos was investigated during a three month field experiment. The spatial heterogeneity of the banana plantation was taken into account by measuring percolation fluxes both under the banana plants and in the interrows with a specially designed lysimeter device installed at 60 cm depth. At the field scale, 0.34% of the pesticide applied was transferred in percolation, 0.13% in runoff. Forty-nine percent of cadusafos losses occurred by percolation under the banana plants, 23% by interrow percolation, and 28% by runoff. Losses were highest during the three weeks following cadusafos application, and this is also when dissipation in the soil was highest (calculated half-life in the soil: 7d). After this period, losses of cadusafos were low, both in soil and waters. Under the banana plant, saturated fluxes carried most of the pesticide, despite total percolation fluxes being at least five-times higher than saturated ones. Although overall pesticide transfer in water was low (0.5% of applied), it was not negligible due to the frequency of pesticide application in these areas. PMID:19053376

  17. Closed-loop adaptive optics using a spatial light modulator for sensing and compensating of optical aberrations in ophthalmic applications

    NASA Astrophysics Data System (ADS)

    Akondi, Vyas; Jewel, Md. Atikur Rahman; Vohnsen, Brian

    2014-09-01

    Sensing and compensating of optical aberrations in closed-loop mode using a single spatial light modulator (SLM) for ophthalmic applications is demonstrated. Notwithstanding the disadvantages of the SLM, in certain cases, this multitasking capability of the device makes it advantageous over existing deformable mirrors (DMs), which are expensive and in general used for aberration compensation alone. A closed-loop adaptive optics (AO) system based on a single SLM was built. Beam resizing optics were used to utilize the large active area of the device and hence make it feasible to generate 137 active subapertures for wavefront sensing. While correcting Zernike aberrations up to fourth order introduced with the help of a DM (for testing purposes), diffraction-limited resolution was achieved. It is shown that matched filter and intensity-weighted centroiding techniques stand out among others. Closed-loop wavefront correction of aberrations in backscattered light from the eyes of three healthy human subjects was demonstrated after satisfactory results were obtained using an artificial eye, which was simulated with a short focal length lens and a sheet of white paper as diffuser. It is shown that the closed-loop AO system based on a single SLM is capable of diffraction-limited correction for ophthalmic applications.

  18. Spatial services grid

    NASA Astrophysics Data System (ADS)

    Cao, Jian; Li, Qi; Cheng, Jicheng

    2005-10-01

    This paper discusses the concept, key technologies and main application of Spatial Services Grid. The technologies of Grid computing and Webservice is playing a revolutionary role in studying the spatial information services. The concept of the SSG (Spatial Services Grid) is put forward based on the SIG (Spatial Information Grid) and OGSA (open grid service architecture). Firstly, the grid computing is reviewed and the key technologies of SIG and their main applications are reviewed. Secondly, the grid computing and three kinds of SIG (in broad sense)--SDG (spatial data grid), SIG (spatial information grid) and SSG (spatial services grid) and their relationships are proposed. Thirdly, the key technologies of the SSG (spatial services grid) is put forward. Finally, three representative applications of SSG (spatial services grid) are discussed. The first application is urban location based services gird, which is a typical spatial services grid and can be constructed on OGSA (Open Grid Services Architecture) and digital city platform. The second application is region sustainable development grid which is the key to the urban development. The third application is Region disaster and emergency management services grid.

  19. DotAGWA: A case study in web-based architectures for connecting surface water models to spatially enabled web applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Automated Geospatial Watershed Assessment (AGWA) tool is a desktop application that uses widely available standardized spatial datasets to derive inputs for multi-scale hydrologic models (Miller et al., 2007). The required data sets include topography (DEM data), soils, climate, and land-cover ...

  20. The effect of application method on the temporal and spatial distribution of neonicotinoid insecticides in greenhouse zinnia and impact on aphid populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Greenhouse trials were designed to evaluate the effect the application technique would have on temporal and spatial movement of neonicotinoid insecticides imidacloprid and thiamethoxam through plant tissue. Mature Zinnia elegans plants were treated by either a soil drench of neonicotinoid insectici...

  1. Spatial organization of the gravitropic response in plants: applicability of the revised local curvature distribution model to Triticum aestivum coleoptiles.

    PubMed

    Meskauskas, A; Jurkoniene, S; Moore, D

    1999-08-01

    The revised local curvature distribution model, which provides accurate computer simulations of the gravitropic response of mushroom stems, was found to produce accurate simulations of the gravitropic reaction of wheat (Triticum aestivum) coleoptiles. The key feature of the mathematical model that enables it to approach universality of application is the assumption that the stem has an autonomic straightening reaction (curvature compensation or 'autotropism'). In the model, the local bending rate for any segment of the organ is determined by the difference between the 'bending signal' (generated by the gravitropic signal perception system) and a 'straightening signal' (which is proportional to the local curvature of the segment). The model reveals three major differences between the gravitropic reactions of wheat coleoptiles and Coprinus mushroom stems. First, in Coprinus, the capacity for autonomic straightening is much more concentrated in the apical region of the stem. Second, local perception of the gravitropic signal, which is necessary for exact simulation in Coprinus, is not needed in wheat coleoptiles (the corresponding constant in the model can be set to zero). Third, the transmission rate of the gravitropic signal is about seven times faster in wheat coleoptiles than in the mushroom stem. Thus, we demonstrate that a single model, depending on the values given to its parameters, is able to simulate the spatial organization of the gravitropic reaction of wheat coleoptiles and Coprinus mushroom stems. The model promises to be a valuable predictive tool in guiding future research into the gravitropic reaction of axial organs of all types. PMID:11542912

  2. The application of quaternions and other spatial representations to the reconstruction of re-entry vehicle motion.

    SciTech Connect

    De Sapio, Vincent

    2010-09-01

    The analysis of spacecraft kinematics and dynamics requires an efficient scheme for spatial representation. While the representation of displacement in three dimensional Euclidean space is straightforward, orientation in three dimensions poses particular challenges. The unit quaternion provides an approach that mitigates many of the problems intrinsic in other representation approaches, including the ill-conditioning that arises from computing many successive rotations. This report focuses on the computational utility of unit quaternions and their application to the reconstruction of re-entry vehicle (RV) motion history from sensor data. To this end they will be used in conjunction with other kinematic and data processing techniques. We will present a numerical implementation for the reconstruction of RV motion solely from gyroscope and accelerometer data. This will make use of unit quaternions due to their numerical efficacy in dealing with the composition of many incremental rotations over a time series. In addition to signal processing and data conditioning procedures, algorithms for numerical quaternion-based integration of gyroscope data will be addressed, as well as accelerometer triangulation and integration to yield RV trajectory. Actual processed flight data will be presented to demonstrate the implementation of these methods.

  3. Design optimization of the sensor spatial arrangement in a direct magnetic field-based localization system for medical applications.

    PubMed

    Marechal, Luc; Shaohui Foong; Zhenglong Sun; Wood, Kristin L

    2015-08-01

    Motivated by the need for developing a neuronavigation system to improve efficacy of intracranial surgical procedures, a localization system using passive magnetic fields for real-time monitoring of the insertion process of an external ventricular drain (EVD) catheter is conceived and developed. This system operates on the principle of measuring the static magnetic field of a magnetic marker using an array of magnetic sensors. An artificial neural network (ANN) is directly used for solving the inverse problem of magnetic dipole localization for improved efficiency and precision. As the accuracy of localization system is highly dependent on the sensor spatial location, an optimization framework, based on understanding and classification of experimental sensor characteristics as well as prior knowledge of the general trajectory of the localization pathway, for design of such sensing assemblies is described and investigated in this paper. Both optimized and non-optimized sensor configurations were experimentally evaluated and results show superior performance from the optimized configuration. While the approach presented here utilizes ventriculostomy as an illustrative platform, it can be extended to other medical applications that require localization inside the body. PMID:26736407

  4. Development of Knowledge Intensive Applications for Hospital

    NASA Astrophysics Data System (ADS)

    Kim, Jongho; Hong, Han-Kuk; Jang, Gil-Sang; Kim, Joung Yeon; Kim, Taehun

    Most studies of medical intelligence system have focused on the development of backend data repositories rather than frontend user applications. Also, they tend to lack systematic development models which demonstrate how user requirements inform system design and implementation. For these reasons, it is highly desirable to show the process of eliciting knowledge requirements in addition to the development process for knowledge-intensive applications. This research covers the implementation of a medical intelligence system based on analysis of knowledge requirements such as OLAP (On-line Analytical Processing) fundamental functionalities and knowledge types. The proposed medical intelligence system provides health care providers and their supporters with the ability to draw meaningful insights from very large, complex data sets. A real life case is presented to illustrate the system’s practical usage. Six application packages are defined, namely: explorer, analyzer, reporter, statistician, visualizer, and meta administrator. Finally, the study concludes with an evaluation of the developed system and future research directions.

  5. Enhancing a Low-Cost Virtual Reality Application through Constructivist Approach: The Case of Spatial Training of Middle Graders

    ERIC Educational Resources Information Center

    Samsudin, Khairulanuar; Rafi, Ahmad; Mohamad Ali, Ahmad Zamzuri; Abd. Rashid, Nazre

    2014-01-01

    The aim of this study is to develop and to test a low-cost virtual reality spatial trainer in terms of its effectiveness in spatial training. The researchers adopted three features deriving from the constructivist perspective to guide the design of the trainer, namely interaction, instruction, and support. The no control pre test post test…

  6. How Students Solve Problems in Spatial Geometry while Using a Software Application for Visualizing 3D Geometric Objects

    ERIC Educational Resources Information Center

    Widder, Mirela; Gorsky, Paul

    2013-01-01

    In schools, learning spatial geometry is usually dependent upon a student's ability to visualize three dimensional geometric configurations from two dimensional drawings. Such a process, however, often creates visual obstacles which are unique to spatial geometry. Useful software programs which realistically depict three dimensional geometric…

  7. Spatially distributed flood forecasting in flash flood prone areas: Application to road network supervision in Southern France

    NASA Astrophysics Data System (ADS)

    Naulin, J.-P.; Payrastre, O.; Gaume, E.

    2013-04-01

    SummaryAccurate flood forecasts are critical to an efficient flood event management strategy. Until now, hydro-meteorological forecasts have mainly been used to establish early-warnings in France (meteorological and flood vigilance maps) or over the world (flash-flood guidances). These forecasts are typically limited either to the main streams covered by the flood forecasting services or to watersheds with specific assets like check dams, which in most cases are well gauged river sections, thus leaving aside large parts of the territory. This paper presents a distributed hydro-meteorological forecasting approach, which makes use of the high spatial and temporal resolution rainfall estimates that are now available, to provide information at ungauged sites. The proposed system intended to detect road inundation risks had initially been developed and tested in areas of limited size. This paper presents the extension of such a system to an entire region (i.e. the Gard region in Southern France), including over 2000 crossing points between rivers and roads and its validation with respect to a large data set of actual reported road inundations observed during recent flash flood events. These initial validation results appear to be most promising. The eventual proposed tool would provide the necessary information for flood event management services to identify the areas at risk and adopt appropriate safety and rescue measures: i.e. pre-positioning of rescue equipment, interruption of the traffic on the exposed roads and determination of safe access or evacuation routes. Moreover, beyond the specific application to the supervision of a road network, the research undertaken herein also provides results for the performance of hydro-meteorological forecasts on ungauged headwaters.

  8. Spatial variation of soil salinity in the Mexicali Valley, Mexico: application of a practical method for agricultural monitoring.

    PubMed

    Judkins, Gabriel; Myint, Soe

    2012-09-01

    The degradation of irrigated lands through the process of soil salinization, or the buildup of salts in the soil, has hampered recent increases in agricultural productivity and threatens the sustainability of large-scale cultivation in critical agricultural regions of the world. Rapid detection of soil salinity on a regional basis has been identified as key for effective mitigation of such land degradation. The ability to detect regional patterns of soil salinity at an accuracy sufficient for regional-scale resource management is demonstrated using Landsat 5 Thematic Mapper (TM) imagery. A case study of the Mexicali Valley of Baja California, Mexico was selected due to the region's agricultural significance and concern for future soil salinity increases. Surface soil salinity was mapped using georeferenced field measurements of electrical conductivity (EC), collected concurrently with Landsat 5 TM imagery. Correlations between EC measurements and common indices derived from the satellite imagery were used to produce a model of soil salinity through regression analysis. Landsat band 7, TNDVI, PCA 1, Tasseled Cap 3 and Tasseled Cap 5 were found to offer the most promising correlations with surface soil salinity. Generally low levels of soil salinity were detected, however, distinct areas of elevated surface salinity were detected at levels potentially impacting sensitive crops cultivated within the region. The difficulty detecting low levels of salinity and the mid-range spatial resolution of Landsat 5 TM imagery restrict the applicability of this methodology to the study of broad regional patterns of degradation most appropriate for use by regional resource managers. PMID:22744157

  9. Application of spatial synoptic classification in evaluating links between heat stress and cardiovascular mortality and morbidity in Prague, Czech Republic

    NASA Astrophysics Data System (ADS)

    Urban, Aleš; Kyselý, Jan

    2015-09-01

    Spatial synoptic classification (SSC) is here first employed in assessing heat-related mortality and morbidity in Central Europe. It is applied for examining links between weather patterns and cardiovascular (CVD) mortality and morbidity in an extended summer season (16 May-15 September) during 1994-2009. As in previous studies, two SSC air masses (AMs)—dry tropical (DT) and moist tropical (MT)—are associated with significant excess CVD mortality in Prague, while effects on CVD hospital admissions are small and insignificant. Excess mortality for ischaemic heart diseases is more strongly associated with DT, while MT has adverse effect especially on cerebrovascular mortality. Links between the oppressive AMs and excess mortality relate also to conditions on previous days, as DT and MT occur in typical sequences. The highest CVD mortality deviations are found 1 day after a hot spell's onset, when temperature as well as frequency of the oppressive AMs are highest. Following this peak is typically DT- to MT-like weather transition, characterized by decrease in temperature and increase in humidity. The transition between upward (DT) and downward (MT) phases is associated with the largest excess CVD mortality, and the change contributes to the increased and more lagged effects on cerebrovascular mortality. The study highlights the importance of critically evaluating SSC's applicability and benefits within warning systems relative to other synoptic and epidemiological approaches. Only a subset of days with the oppressive AMs is associated with excess mortality, and regression models accounting for possible meteorological and other factors explain little of the mortality variance.

  10. Identifying Spatial Clusters of Schistosomiasis in Anhui Province of China: A Study from the Perspective of Application

    PubMed Central

    Sun, Liqian; Chen, Yue; Lynn, Henry; Wang, Qizhi; Zhang, Shiqing; Li, Rui; Xia, Congcong; Jiang, Qingwu; Hu, Yi; Gao, Fenghua; Zhang, Zhijie

    2015-01-01

    With the strategy shifting from morbidity control to transmission interruption, the burden of schistosomiasis in China has been declining over the past decade. However, further controls of the epidemic in the lake and marshland regions remain a challenge. Prevalence data at county level were obtained from the provincial surveillance system in Anhui during 1997–2010. Spatial autocorrelation analysis and spatial scan statistics were combined to assess the spatial pattern of schistosomiasis. The spatial-temporal cluster analysis based on retrospective space-time scan statistics was further used to detect risk clusters. The Global Moran’s I coefficients were mostly statistically significant during 1997–2004 but not significant during 2005–2010. The clusters detected by two spatial cluster methods occurred in Nanling, Tongling, Qingyang and Wuhu during 1997–2004, and Guichi and Wuhu from 2005 to 2010, respectively. Spatial-temporal cluster analysis revealed 2 main clusters, namely Nanling (1999–2002) and Guichi (2005–2008). The clustering regions were significantly narrowed while the spatial extent became scattered during the study period. The high-risk areas shifted from the low reaches of the Yangtze River to the upper stream, suggesting the focus of schistosomiasis control should be shifted accordingly and priority should be given to the snail habitats within the high-risk areas of schistosomiasis. PMID:26393632

  11. Developing an entropy-based model of spatial information estimation and its application in the design of precipitation gauge networks

    NASA Astrophysics Data System (ADS)

    Su, Ho-Ting; You, Gene Jiing-Yun

    2014-11-01

    This study proposed a spatial information estimation model for the analysis of precipitation gauge networks, to improve on previous methods based on information theory. The proposed model employs a two-dimensional transinformation-distance (T-D) relationship in conjunction with multivariate information approximation to estimate transinformation to ungauged locations from existing stations, while taking into consideration the influence of multiple stations and anisotropy. The proposed model is used to evaluate the spatial distribution of precipitation data and the characteristics of information transfer, which are then applied in a spatial optimization algorithm for the selection of additional station locations. This framework was implemented to investigate temporal and spatial patterns in information content in the Shihmen Reservoir watershed. The results demonstrate obvious anisotropy associated with the delivery of information. By comparing different cases, it was determined that the efficiency of information delivery dominates the spatial distribution of the information content, such that eccentricity is merely supplemental. Efficiency in information delivery is also heavily influenced by temporal scale. For data covering long intervals (monthly and annual), efficiency in the delivery of information is relatively high, while the uncertainty or heterogeneity of hourly or daily time series produces low spatial correlations due to the inefficient delivery of information. The proposed spatial optimization algorithm confirmed that the optimal location for new stations lies close to the center of low information zones. Additional stations could improve information content considerably; however, the margin of improvement decreases with the number of stations.

  12. Identifying Spatial Clusters of Schistosomiasis in Anhui Province of China: A Study from the Perspective of Application.

    PubMed

    Sun, Liqian; Chen, Yue; Lynn, Henry; Wang, Qizhi; Zhang, Shiqing; Li, Rui; Xia, Congcong; Jiang, Qingwu; Hu, Yi; Gao, Fenghua; Zhang, Zhijie

    2015-09-01

    With the strategy shifting from morbidity control to transmission interruption, the burden of schistosomiasis in China has been declining over the past decade. However, further controls of the epidemic in the lake and marshland regions remain a challenge. Prevalence data at county level were obtained from the provincial surveillance system in Anhui during 1997-2010. Spatial autocorrelation analysis and spatial scan statistics were combined to assess the spatial pattern of schistosomiasis. The spatial-temporal cluster analysis based on retrospective space-time scan statistics was further used to detect risk clusters. The Global Moran's I coefficients were mostly statistically significant during 1997-2004 but not significant during 2005-2010. The clusters detected by two spatial cluster methods occurred in Nanling, Tongling, Qingyang and Wuhu during 1997-2004, and Guichi and Wuhu from 2005 to 2010, respectively. Spatial-temporal cluster analysis revealed 2 main clusters, namely Nanling (1999-2002) and Guichi (2005-2008). The clustering regions were significantly narrowed while the spatial extent became scattered during the study period. The high-risk areas shifted from the low reaches of the Yangtze River to the upper stream, suggesting the focus of schistosomiasis control should be shifted accordingly and priority should be given to the snail habitats within the high-risk areas of schistosomiasis. PMID:26393632

  13. Spatial wildlife-vehicle collision models: a review of current work and its application to transportation mitigation projects.

    PubMed

    Gunson, Kari E; Mountrakis, Giorgos; Quackenbush, Lindi J

    2011-04-01

    In addition to posing a serious risk to motorist safety, vehicle collisions with wildlife are a significant threat for many species. Previous spatial modeling has concluded that wildlife-vehicle collisions (WVCs) exhibit clustering on roads, which is attributed to specific landscape and road-related factors. We reviewed twenty-four published manuscripts that used generalized linear models to statistically determine the influence that numerous explanatory predictors have on the location of WVCs. Our motivation was to summarize empirical WVC findings to facilitate application of this knowledge to planning, and design of mitigation strategies on roads. In addition, commonalities between studies were discussed and recommendations for future model design were made. We summarized the type and measurement of each significant predictor and whether they potentially increased or decreased the occurrence of collisions with ungulates, carnivores, small-medium vertebrates, birds, and amphibians and reptiles. WVCs commonly occurred when roads bisect favorable cover, foraging, or breeding habitat for specific species or groups of species. WVCs were generally highest on road sections with high traffic volumes, or low motorist visibility, and when roads cut through drainage movement corridors, or level terrain. Ungulates, birds, small-medium vertebrates, and carnivore collision locations were associated with road-side vegetation and other features such as salt pools. In several cases, results were spurious due to confounding and interacting predictors within the same model. For example, WVCs were less likely to occur when a road bisected steep slopes; however, steep slopes may be located along specific road-types and habitat that also influence the occurrence of WVCs. In conclusion, this review showed that much of the current literature has gleaned the obvious, broad-scale relationships between WVCs and predictors from available data sets, and localized studies can provide unique

  14. Condensation of earthquake location distributions: Optimal spatial information encoding and application to multifractal analysis of south Californian seismicity.

    PubMed

    Kamer, Yavor; Ouillon, Guy; Sornette, Didier; Wössner, Jochen

    2015-08-01

    We present the "condensation" method that exploits the heterogeneity of the probability distribution functions (PDFs) of event locations to improve the spatial information content of seismic catalogs. As its name indicates, the condensation method reduces the size of seismic catalogs while improving the access to the spatial information content of seismic catalogs. The PDFs of events are first ranked by decreasing location errors and then successively condensed onto better located and lower variance event PDFs. The obtained condensed catalog differs from the initial catalog by attributing different weights to each event, the set of weights providing an optimal spatial representation with respect to the spatially varying location capability of the seismic network. Synthetic tests on fractal distributions perturbed with realistic location errors show that condensation improves spatial information content of the original catalog, which is quantified by the likelihood gain per event. Applied to Southern California seismicity, the new condensed catalog highlights major mapped fault traces and reveals possible additional structures while reducing the catalog length by ∼25%. The condensation method allows us to account for location error information within a point based spatial analysis. We demonstrate this by comparing the multifractal properties of the condensed catalog locations with those of the original catalog. We evidence different spatial scaling regimes characterized by distinct multifractal spectra and separated by transition scales. We interpret the upper scale as to agree with the thickness of the brittle crust, while the lower scale (2.5 km) might depend on the relocation procedure. Accounting for these new results, the epidemic type aftershock model formulation suggests that, contrary to previous studies, large earthquakes dominate the earthquake triggering process. This implies that the limited capability of detecting small magnitude events cannot be used

  15. Condensation of earthquake location distributions: Optimal spatial information encoding and application to multifractal analysis of south Californian seismicity

    NASA Astrophysics Data System (ADS)

    Kamer, Yavor; Ouillon, Guy; Sornette, Didier; Wössner, Jochen

    2015-08-01

    We present the "condensation" method that exploits the heterogeneity of the probability distribution functions (PDFs) of event locations to improve the spatial information content of seismic catalogs. As its name indicates, the condensation method reduces the size of seismic catalogs while improving the access to the spatial information content of seismic catalogs. The PDFs of events are first ranked by decreasing location errors and then successively condensed onto better located and lower variance event PDFs. The obtained condensed catalog differs from the initial catalog by attributing different weights to each event, the set of weights providing an optimal spatial representation with respect to the spatially varying location capability of the seismic network. Synthetic tests on fractal distributions perturbed with realistic location errors show that condensation improves spatial information content of the original catalog, which is quantified by the likelihood gain per event. Applied to Southern California seismicity, the new condensed catalog highlights major mapped fault traces and reveals possible additional structures while reducing the catalog length by ˜25 % . The condensation method allows us to account for location error information within a point based spatial analysis. We demonstrate this by comparing the multifractal properties of the condensed catalog locations with those of the original catalog. We evidence different spatial scaling regimes characterized by distinct multifractal spectra and separated by transition scales. We interpret the upper scale as to agree with the thickness of the brittle crust, while the lower scale (2.5 km) might depend on the relocation procedure. Accounting for these new results, the epidemic type aftershock model formulation suggests that, contrary to previous studies, large earthquakes dominate the earthquake triggering process. This implies that the limited capability of detecting small magnitude events cannot be

  16. Relative impacts of the fragmentation and spatial structure of habitats on freshwater fish distributions: application on French watersheds (Invited)

    NASA Astrophysics Data System (ADS)

    Le Pichon, C.; Belliard, J.; Talès, E.; Gorges, G.; Clément, F.

    2009-12-01

    Most of the rivers of the Ile de France region, intimately linked with the megalopolis of Paris, are severely altered and freshwater fishes are exposed to habitat alteration, reduced connectivity and pollution. Several species thus present fragmented distributions and decreasing densities. In this context, the European Water Framework Directive (2000) has goals of hydrosystems rehabilitation and no further damage. In particular, the preservation and restoration of ecological connectivity of river networks is a key element for fish populations. These goals require the identification of natural and anthropological factors which influence the spatial distribution of species. We have proposed a riverscape approach, based on landscape ecology concepts, combined with a set of spatial analysis methods to assess the multiscale relationships between the spatial pattern of fish habitats and processes depending on fish movements. In particular, we used this approach to test the relative roles of spatial arrangement of fish habitats and the presence of physical barriers in explaining fish spatial distributions in a small rural watershed (106 km2). We performed a spatially continuous analysis of fish-habitat relationships. Fish habitats and physical barriers were mapped along the river network (33 km) with a GPS and imported into a GIS. In parallel, a longitudinal electrofishing survey of the distribution and abundance of fishes was made using a point abundance sampling scheme. Longitudinal arrangement of fish habitats were evaluated using spatial analysis methods: patch/distance metrics and moving window analysis. Explanatory models were developed to test the relative contribution of local environmental variables and spatial context in explaining fish presence. We have recorded about 100 physical barriers, on average one every 330 meters; most artificial barriers were road pipe culverts, falls associated with ponds and sluice gates. Contrasted fish communities and densities

  17. An application of GIS and Bayesian network in studying spatial-causal relations between enterprises and environmental factors

    NASA Astrophysics Data System (ADS)

    Shen, Tiyan; Li, Xi; Li, Maiqing

    2009-10-01

    The paper intends to employ Geographic Information System (GIS) and Bayesian Network to discover the spatial causality between enterprises and environmental factors in Beijing Metropolis. The census data of Beijing was spatialized by means of GIS in the beginning, and then the training data was made using density mapping technique. Base on the training data, the structure of a Bayesian Network was learnt with the help of Maximum Weight Spanning Tree. Eight direct relations were discussed in the end, of which, the most exciting discovery, "Enterprise-Run Society", as the symbol of the former planned economy, was emphasized in the spatial relations between heavy industry and schools. Though the final result is not so creative in economic perspective, it is of significance in technique view due to all discoveries were drawn from data, therefore leading to the realization of the importance of GIS and data mining to economic geography research.

  18. Analysis of the spatial climate structure from a viticultural perspective. Application to determine viticulture suitability and zonification in Extremadura (Spain)

    NASA Astrophysics Data System (ADS)

    Rebollo, Francisco J.; Moral, Francisco J.; Paniagua, Luís L.; García, Abelardo

    2014-05-01

    The basis for assessing the suitability for viticulture in wine regions is an accurate depiction of the temperature spatial distribution. Thus, using data for a long time internal (1980-2011) and from 117 meteorological stations, four bioclimatic indices were calculated and their spatial distribution patterns were mapped using a multivariate method, the regression-kriging technique. It was obtained that the spatial variability of climate within Extremaduran natural regions (NRs) is significant. Although the warmer conditions predominate in Extremadura, some NRs have part of their territory by up to eight climate classes; this information enables a better understanding of the viticulture suitability within each NR and delineating homogeneous zones. Finally, comparisons of Extremaduran NRs with others worlwide were conducted, which should be taken into account to select varieties and assess the possibilities of producing new wines.

  19. Calculation of spatial distribution of optical escape factor and its application to He I collisional-radiative model

    SciTech Connect

    Iida, Yohei; Kado, Shinichiro; Tanaka, Satoru

    2010-12-15

    An integral analytical formula for a spatial distribution of the optical escape factor (OEF) in an infinite cylindrical plasma is derived as a function of an arbitrary upper state spatial density profile, the temperature ratio of the upper state to the lower state, and the optical depth of the corresponding transition. Test calculations are carried out for three different upper state profiles, i.e., uniform (rectangular), parabolic, and Gaussian upper state profiles. The OEF takes on negative values at the periphery of the parabolic and Gaussian upper state profiles. These characteristics cannot be expressed by the conventional OEF formulas derived for the center of the plasma, even though the optical depth is increased. In addition to the analytical derivation of the formula, two practical formulas are proposed: an empirical formula of the spatial distribution of the OEF for the Gaussian upper state density profile and a linear formula of the OEF distribution for upper state profiles that are expressed as linear combinations. These formulas enable us to calculate the spatial distribution of the OEF for the multiple-Gaussian upper state profile without the need for time-consuming integral calculations.

  20. Spatial and temporal single-cell volume estimation by a fluorescence imaging technique with application to astrocytes in primary culture

    NASA Astrophysics Data System (ADS)

    Khatibi, Siamak; Allansson, Louise; Gustavsson, Tomas; Blomstrand, Fredrik; Hansson, Elisabeth; Olsson, Torsten

    1999-05-01

    Cell volume changes are often associated with important physiological and pathological processes in the cell. These changes may be the means by which the cell interacts with its surrounding. Astroglial cells change their volume and shape under several circumstances that affect the central nervous system. Following an incidence of brain damage, such as a stroke or a traumatic brain injury, one of the first events seen is swelling of the astroglial cells. In order to study this and other similar phenomena, it is desirable to develop technical instrumentation and analysis methods capable of detecting and characterizing dynamic cell shape changes in a quantitative and robust way. We have developed a technique to monitor and to quantify the spatial and temporal volume changes in a single cell in primary culture. The technique is based on two- and three-dimensional fluorescence imaging. The temporal information is obtained from a sequence of microscope images, which are analyzed in real time. The spatial data is collected in a sequence of images from the microscope, which is automatically focused up and down through the specimen. The analysis of spatial data is performed off-line and consists of photobleaching compensation, focus restoration, filtering, segmentation and spatial volume estimation.

  1. Correction of systematic spatial noise in push-broom hyperspectral sensors: application to CHRIS/PROBA images.

    PubMed

    Gómez-Chova, Luis; Alonso, Luis; Guanter, Luis; Camps-Valls, Gustavo; Calpe, Javier; Moreno, José

    2008-10-01

    Hyperspectral remote sensing images are affected by different types of noise. In addition to typical random noise, nonperiodic partially deterministic disturbance patterns generally appear in the data. These patterns, which are intrinsic to the image formation process, are characterized by a high degree of spatial and spectral coherence. We present a new technique that faces the problem of removing the spatially coherent noise known as vertical striping, usually found in images acquired by push-broom sensors. The developed methodology is tested on data acquired by the Compact High Resolution Imaging Spectrometer (CHRIS) onboard the Project for On-board Autonomy (PROBA) orbital platform, which is a typical example of a push-broom instrument exhibiting a relatively high noise component. The proposed correction method is based on the hypothesis that the vertical disturbance presents higher spatial frequencies than the surface radiance. A technique to exclude the contribution of the spatial high frequencies of the surface from the destriping process is introduced. First, the performance of the proposed algorithm is tested on a set of realistic synthetic images with added modeled noise in order to quantify the noise reduction and the noise estimation accuracy. Then, algorithm robustness is tested on more than 350 real CHRIS images from different sites, several acquisition modes (different spatial and spectral resolutions), and covering the full range of possible sensor temperatures. The proposed algorithm is benchmarked against the CHRIS reference algorithm. Results show excellent rejection of the noise pattern with respect to the original CHRIS images, especially improving the removal in those scenes with a natural high contrast. However, some low-frequency components still remain. In addition, the developed correction model captures and corrects the dependency of the noise patterns on sensor temperature, which confirms the robustness of the presented approach. PMID

  2. Simulating Human and Environmental Exposure from Hand-Held Knapsack Pesticide Application: Be-WetSpa-Pest, an Integrative, Spatially Explicit Modeling Approach.

    PubMed

    Binder, Claudia R; García-Santos, Glenda; Andreoli, Romano; Diaz, Jaime; Feola, Giuseppe; Wittensoeldner, Moritz; Yang, Jing

    2016-05-25

    This paper presents an integrative and spatially explicit modeling approach for analyzing human and environmental exposure from pesticide application of smallholders in the potato-producing Andean region in Colombia. The modeling approach fulfills the following criteria: (i) it includes environmental and human compartments; (ii) it contains a behavioral decision-making model for estimating the effect of policies on pesticide flows to humans and the environment; (iii) it is spatially explicit; and (iv) it is modular and easily expandable to include additional modules, crops, or technologies. The model was calibrated and validated for the Vereda La Hoya and was used to explore the effect of different policy measures in the region. The model has moderate data requirements and can be adapted relatively easily to other regions in developing countries with similar conditions. PMID:26828854

  3. Method and apparatus for spatially variable rate application of agricultural chemicals based on remotely sensed vegetation data

    NASA Technical Reports Server (NTRS)

    Hood, Kenneth Brown (Inventor); Seal, Michael R. (Inventor); Lewis, Mark David (Inventor); Johnson, James William (Inventor)

    2004-01-01

    Remotely sensed spectral image data are used to develop a Vegetation Index file which represents spatial variations of actual crop vigor throughout a field that is under cultivation. The latter information is processed to place it in a format that can be used by farm personnel to correlate and calibrate it with actually observed crop conditions existing at control points within the field. Based on the results, farm personnel formulate a prescription request, which is forwarded via email or FTP to a central processing site, where the prescription is prepared. The latter is returned via email or FTP to on-side farm personnel, who can load it into a controller on a spray rig that directly applies inputs to the field at a spatially variable rate.

  4. Method and system for spatially variable rate application of agricultural chemicals based on remotely sensed vegetation data

    NASA Technical Reports Server (NTRS)

    Hood, Kenneth Brown (Inventor); Seal, Michael R. (Inventor); Lewis, Mark David (Inventor); Johnson, James William (Inventor)

    2007-01-01

    Remotely sensed spectral image data are used to develop a Vegetation Index file which represents spatial variations of actual crop vigor throughout a field that is under cultivation. The latter information is processed to place it in a format that can be used by farm personnel to correlate and calibrate it with actually observed crop conditions existing at control points within the field. Based on the results, farm personnel formulate a prescription request, which is forwarded via email or FTP to a central processing site, where the prescription is prepared. The latter is returned via email or FTP to on-side farm personnel, who can load it into a controller on a spray rig that directly applies inputs to the field at a spatially variable rate.

  5. SEHR-ECHO v1.0: a Spatially-Explicit Hydrologic Response model for ecohydrologic applications

    NASA Astrophysics Data System (ADS)

    Schaefli, Bettina; Nicótina, Ludovico; Da Ronco, Pierfrancesco; Bertuzzo, Enrico; Rinaldo, Andrea

    2015-04-01

    We present here the SEHR-ECHO model, which stands for Spatially Explicit Hydrologic Response (SEHR) model developed at the Laboratory of Ecohydrology (ECHO) of the Ecole Polytechnique Fédérale de Lausanne. The model is being developed for the spatially-explicit simulation of streamflow and transport processes at the catchment scale. The key concept of the model is the formulation of water transport by geomorphologic travel time distributions: the mobilization of water (and possibly dissolved solutes) is simulated at the subcatchment scale and the resulting responses are convolved with the travel paths distribution within the river network to obtain the hydrologic response at the catchment outlet. The Matlab source code of the current version for alpine streamflow simulation is already freely available. A truly free open source version using Python will become available in the future.

  6. 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

  7. Enabling multi-disciplinary climate science through the application of GIS and high-resolution spatial data

    NASA Astrophysics Data System (ADS)

    Altmann, G.; Wilson, C. J.; Gangodagamage, C.; Wullschleger, S. D.

    2013-12-01

    Multidisciplinary field studies in climate science require effective methods for communicating data needs across a broad range of spatial and temporal scales. The Next Generation Ecosystem Experiment-Arctic seeks to reduce uncertainty in climate prediction by investigating critical land-atmosphere interactions in terrestrial ecosystems of Alaska. Using high-resolution LiDAR imagery and GIS, we applied geographic visualization principles to synthesize spatial data and facilitate cross-discipline communication for field planning, instrument implementation and model data integration. We hypothesized that providing three-dimensional (3D) representation of arctic landscape features would enhance perception and provide an effective medium to better optimize further field studies and analyses. Results indicate that key landscape features, such as polygonal ground and drained thaw lake basins (DTLB), represented in 3D maps offered superior recognition and differentiation among these features than traditional 2D maps. When overlaying 3D landscape features with high-resolution spatial data, such as WorldView-2 panchromatic imagery, digital elevation models (DEM), remotely derived indexes such as NDVI, or site instrumentation, further recognition and quantification of landscape processes was attained. Conversely, we observed that data inclusion in excess resulted in poor cognition of key features and/or themes. At various scales, 3D visualization proved to be effective at characterizing both large-scale (1:50) site level characteristics (polygon/trough), as well as small-scale (1:500) regional features (high vs. low polygon terrain). We conclude that applying GIS and high-resolution spatial data to create 3D visualizations is highly effective in representing key arctic landscape features across a wide range of scales. When combining multiple data layers (in moderation), these visualizations prove to be a valuable tool for communicating data needs, refining field

  8. Spatial Data Analysis.

    PubMed

    Banerjee, Sudipto

    2016-03-18

    With increasing accessibility to geographic information systems (GIS) software, statisticians and data analysts routinely encounter scientific data sets with geocoded locations. This has generated considerable interest in statistical modeling for location-referenced spatial data. In public health, spatial data routinely arise as aggregates over regions, such as counts or rates over counties, census tracts, or some other administrative delineation. Such data are often referred to as areal data. This review article provides a brief overview of statistical models that account for spatial dependence in areal data. It does so in the context of two applications: disease mapping and spatial survival analysis. Disease maps are used to highlight geographic areas with high and low prevalence, incidence, or mortality rates of a specific disease and the variability of such rates over a spatial domain. They can also be used to detect hot spots or spatial clusters that may arise owing to common environmental, demographic, or cultural effects shared by neighboring regions. Spatial survival analysis refers to the modeling and analysis for geographically referenced time-to-event data, where a subject is followed up to an event (e.g., death or onset of a disease) or is censored, whichever comes first. Spatial survival analysis is used to analyze clustered survival data when the clustering arises from geographical regions or strata. Illustrations are provided in these application domains. PMID:26789381

  9. Approaches to Capture Variance Differences in Rest fMRI Networks in the Spatial Geometric Features: Application to Schizophrenia

    PubMed Central

    Gopal, Shruti; Miller, Robyn L.; Baum, Stefi A.; Calhoun, Vince D.

    2016-01-01

    Identification of functionally connected regions while at rest has been at the forefront of research focusing on understanding interactions between different brain regions. Studies have utilized a variety of approaches including seed based as well as data-driven approaches to identifying such networks. Most such techniques involve differentiating groups based on group mean measures. There has been little work focused on differences in spatial characteristics of resting fMRI data. We present a method to identify between group differences in the variability in the cluster characteristics of network regions within components estimated via independent vector analysis (IVA). IVA is a blind source separation approach shown to perform well in capturing individual subject variability within a group model. We evaluate performance of the approach using simulations and then apply to a relatively large schizophrenia data set (82 schizophrenia patients and 89 healthy controls). We postulate, that group differences in the intra-network distributional characteristics of resting state network voxel intensities might indirectly capture important distinctions between the brain function of healthy and clinical populations. Results demonstrate that specific areas of the brain, superior, and middle temporal gyrus that are involved in language and recognition of emotions, show greater component level variance in amplitude weights for schizophrenia patients than healthy controls. Statistically significant correlation between component level spatial variance and component volume was observed in 19 of the 27 non-artifactual components implying an evident relationship between the two parameters. Additionally, the greater spread in the distance of the cluster peak of a component from the centroid in schizophrenia patients compared to healthy controls was observed for seven components. These results indicate that there is hidden potential in exploring variance and possibly higher

  10. Statistical monitoring of spatial patterns of environmental indices for integrated ecosystem assessment: Application to the Bay of Biscay pelagic zone

    NASA Astrophysics Data System (ADS)

    Woillez, Mathieu; Petitgas, Pierre; Huret, Martin; Struski, Caroline; Léger, Fabien

    2010-10-01

    Monitoring the environment of fish is a key component of the ecosystem approach to fisheries management. Here, we propose a methodology to statistically monitor time series of maps of environmental indices. These maps were derived from a 37-year hindcast of a coupled physical-biogeochemical model. The space-time variability in the maps was decomposed using empirical orthogonal functions into time-invariant spatial patterns and time-varying amplitudes for these patterns. A statistical process control chart was then applied to the time series of the amplitudes. In that way, changes were detected with known statistical performance. The monitoring system also specified how long the changes lasted and which years, seasons and zones were affected. Results for all indices were assembled in an integrative dashboard of the detected deviations. For illustration, the procedure was applied to the Bay of Biscay pelagic zone. The selected environmental indices characterized the evolution of hydrological structures such as fronts and river plumes, as well as changes in temperature, water column stratification, horizontal current flow and primary production. A major result was that, in the last decade, sea surface temperature showed repeated significant shifts towards warming, which were largest in the northern half of the Bay, while the spatial extension of river plumes over the shelf alternated between wet and dry years. From 2005, several other indices showed repeated significant deviations: increase in sea bottom temperature, increase in the depth of the pycnocline and changes in coastal currents. The procedure provided an integrated view of ecosystem variability and change for all its components and their spatial organization.

  11. Spatial variations in the consumption of illicit stimulant drugs across Australia: A nationwide application of wastewater-based epidemiology.

    PubMed

    Lai, Foon Yin; O'Brien, Jake; Bruno, Raimondo; Hall, Wayne; Prichard, Jeremy; Kirkbride, Paul; Gartner, Coral; Thai, Phong; Carter, Steve; Lloyd, Belinda; Burns, Lucy; Mueller, Jochen

    2016-10-15

    Obtaining representative information on illicit drug use and patterns across a country remains difficult using surveys because of low response rates and response biases. A range of studies have used wastewater-based epidemiology (WBE) as a complementary approach to monitor community-wide illicit drug use. In Australia, no large-scale WBE studies have been conducted to date to reveal illicit drug use profiles in a national context. In this study, we performed the first Australia-wide WBE monitoring to examine spatial patterns in the use of three illicit stimulants (cocaine, as its human metabolite benzoylecgonine; methamphetamine; and 3,4-methylendioxymethamphetamine (MDMA)). A total of 112 daily composite wastewater samples were collected from 14 wastewater treatment plants across four states and two territories. These covered approximately 40% of the Australian population. We identified and quantified illicit drug residues using liquid chromatography coupled with tandem mass spectrometry. There were distinctive spatial patterns of illicit stimulant use in Australia. Multivariate analyses showed that consumption of cocaine and MDMA was higher in the large cities than in rural areas. Also, cocaine consumption differed significantly between different jurisdictions. Methamphetamine consumption was more similar between urban and rural locations. Only a few cities had elevated levels of use. Extrapolation of the WBE estimates suggested that the annual consumption was 3tonnes for cocaine and 9tonnes combined for methamphetamine and MDMA, which outweighed the annual seizure amount by 25 times and 45 times, respectively. These ratios imply the difficulty of detecting the trafficking of these stimulants in Australia, possibly more so for methamphetamine than cocaine. The obtained spatial pattern of use was compared with that in the most recent national household survey. Together both WBE and survey methods provide a more comprehensive evaluation of drug use that can assist

  12. Approaches to Capture Variance Differences in Rest fMRI Networks in the Spatial Geometric Features: Application to Schizophrenia.

    PubMed

    Gopal, Shruti; Miller, Robyn L; Baum, Stefi A; Calhoun, Vince D

    2016-01-01

    Identification of functionally connected regions while at rest has been at the forefront of research focusing on understanding interactions between different brain regions. Studies have utilized a variety of approaches including seed based as well as data-driven approaches to identifying such networks. Most such techniques involve differentiating groups based on group mean measures. There has been little work focused on differences in spatial characteristics of resting fMRI data. We present a method to identify between group differences in the variability in the cluster characteristics of network regions within components estimated via independent vector analysis (IVA). IVA is a blind source separation approach shown to perform well in capturing individual subject variability within a group model. We evaluate performance of the approach using simulations and then apply to a relatively large schizophrenia data set (82 schizophrenia patients and 89 healthy controls). We postulate, that group differences in the intra-network distributional characteristics of resting state network voxel intensities might indirectly capture important distinctions between the brain function of healthy and clinical populations. Results demonstrate that specific areas of the brain, superior, and middle temporal gyrus that are involved in language and recognition of emotions, show greater component level variance in amplitude weights for schizophrenia patients than healthy controls. Statistically significant correlation between component level spatial variance and component volume was observed in 19 of the 27 non-artifactual components implying an evident relationship between the two parameters. Additionally, the greater spread in the distance of the cluster peak of a component from the centroid in schizophrenia patients compared to healthy controls was observed for seven components. These results indicate that there is hidden potential in exploring variance and possibly higher

  13. Evaluating uncertainty in predicting spatially variable representative elementary scales in fractured aquifers, with application to Turkey Creek Basin, Colorado

    USGS Publications Warehouse

    Wellman, T.P.; Poeter, E.P.

    2006-01-01

    Computational limitations and sparse field data often mandate use of continuum representation for modeling hydrologic processes in large-scale fractured aquifers. Selecting appropriate element size is of primary importance because continuum approximation is not valid for all scales. The traditional approach is to select elements by identifying a single representative elementary scale (RES) for the region of interest. Recent advances indicate RES may be spatially variable, prompting unanswered questions regarding the ability of sparse data to spatially resolve continuum equivalents in fractured aquifers. We address this uncertainty of estimating RES using two techniques. In one technique we employ data-conditioned realizations generated by sequential Gaussian simulation. For the other we develop a new approach using conditioned random walks and nonparametric bootstrapping (CRWN)- We evaluate the effectiveness of each method under three fracture densities, three data sets, and two groups of RES analysis parameters. In sum, 18 separate RES analyses are evaluated, which indicate RES magnitudes may be reasonably bounded using uncertainty analysis, even for limited data sets and complex fracture structure. In addition, we conduct a field study to estimate RES magnitudes and resulting uncertainty for Turkey Creek Basin, a crystalline fractured rock aquifer located 30 km southwest of Denver, Colorado. Analyses indicate RES does not correlate to rock type or local relief in several instances but is generally lower within incised creek valleys and higher along mountain fronts. Results of this study suggest that (1) CRWN is an effective and computationally efficient method to estimate uncertainty, (2) RES predictions are well constrained using uncertainty analysis, and (3) for aquifers such as Turkey Creek Basin, spatial variability of RES is significant and complex. Copyright 2006 by the American Geophysical Union.

  14. Application of group analysis to the spatially homogeneous and isotropic Boltzmann equation with source using its Fourier image

    NASA Astrophysics Data System (ADS)

    Grigoriev, Yurii N.; Meleshko, Sergey V.; Suriyawichitseranee, Amornrat

    2015-06-01

    Group analysis of the spatially homogeneous and molecular energy dependent Boltzmann equations with source term is carried out. The Fourier transform of the Boltzmann equation with respect to the molecular velocity variable is considered. The correspondent determining equation of the admitted Lie group is reduced to a partial differential equation for the admitted source. The latter equation is analyzed by an algebraic method. A complete group classification of the Fourier transform of the Boltzmann equation with respect to a source function is given. The representation of invariant solutions and corresponding reduced equations for all obtained source functions are also presented.

  15. 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.

  16. Geographic representation in spatial analysis

    NASA Astrophysics Data System (ADS)

    Miller, Harvey J.

    Spatial analysis mostly developed in an era when data was scarce and computational power was expensive. Consequently, traditional spatial analysis greatly simplifies its representations of geography. The rise of geographic information science (GISci) and the changing nature of scientific questions at the end of the 20th century suggest a comprehensive re-examination of geographic representation in spatial analysis. This paper reviews the potential for improved representations of geography in spatial analysis. Existing tools in spatial analysis and new tools available from GISci have tremendous potential for bringing more sophisticated representations of geography to the forefront of spatial analysis theory and application.

  17. Spatial cognition

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary Kister; Remington, Roger

    1988-01-01

    Spatial cognition is the ability to reason about geometric relationships in the real (or a metaphorical) world based on one or more internal representations of those relationships. The study of spatial cognition is concerned with the representation of spatial knowledge, and our ability to manipulate these representations to solve spatial problems. Spatial cognition is utilized most critically when direct perceptual cues are absent or impoverished. Examples are provided of how human spatial cognitive abilities impact on three areas of space station operator performance: orientation, path planning, and data base management. A videotape provides demonstrations of relevant phenomena (e.g., the importance of orientation for recognition of complex, configural forms). The presentation is represented by abstract and overhead visuals only.

  18. SEHR-ECHO v1.0: a Spatially-Explicit Hydrologic Response model for ecohydrologic applications

    NASA Astrophysics Data System (ADS)

    Schaefli, B.; Nicótina, L.; Imfeld, C.; Da Ronco, P.; Bertuzzo, E.; Rinaldo, A.

    2014-03-01

    This paper presents the Spatially-Explicit Hydrologic Response (SEHR) model developed at the Laboratory of Ecohydrology of the Ecole Polytechnique Fédérale de Lausanne for the simulation of hydrological processes at the catchment scale. The key concept of the model is the formulation of water transport by geomorphologic travel time distributions through gravity-driven transitions among geomorphic states: the mobilization of water (and possibly dissolved solutes) is simulated at the sub-catchment scale and the resulting responses are convolved with the travel paths distribution within the river network to obtain the hydrologic response at the catchment outlet. The model thus breaks down the complexity of the hydrologic response into an explicit geomorphological combination of dominant spatial patterns of precipitation input and of hydrologic process controls. Nonstationarity and nonlinearity effects are tackled through soil moisture dynamics in the active soil layer. We present here the basic model set-up for precipitation-runoff simulation. The performance of the model is illustrated for a snow-dominated catchment in Switzerland with a small glacier cover.

  19. A Critical Examination of Spatial Biases Between MODIS and MISR Aerosol Products - Application for Potential AERONET Deployment

    NASA Technical Reports Server (NTRS)

    Shi, Y.; Zhang, J.; Reid, J. S.; Hyer, E. J.; Eck, T. F.; Holben, B. N.; Kahn, R. A.

    2011-01-01

    AErosol RObotic NETwork (AERONET) data are the primary benchmark for evaluating satellite-retrieved aerosol properties. However, despite its extensive coverage, the representativeness of the AERONET data is rarely discussed. Indeed, many studies have shown that satellite retrieval biases have a significant degree of spatial correlation that may be problematic for higher-level processes or inverse-emissions-modeling studies. To consider these issues and evaluate relative performance in regions of few surface observations, cross-comparisons between the Aerosol Optical Depth (AOD) products of operational MODIS Collection 5.1 Dark Target (DT) and operational MODIS Collection 5.1 Deep Blue (DB) with MISR version 22 were conducted. Through such comparisons, we can observe coherent spatial features of the AOD bias while side-stepping the full analysis required for determining when or where either retrieval is more correct. We identify regions where MODIS to MISR AOD ratios were found to be above 1.4 and below 0.7. Regions where lower boundary condition uncertainty is likely to be a dominant factor include portions of Western North America, the Andes mountains, Saharan Africa, the Arabian Peninsula, and Central Asia. Similarly, microphysical biases may be an issue in South America, and specific parts of Southern Africa, India Asia, East Asia, and Indonesia. These results help identify high-priority locations for possible future deployments of both in situ and ground based remote sensing measurements. The Supplement includes a km1 file.

  20. High-Resolution X-ray Microprobe Using a Spatial Filter and Its Application to Micro-XAFS Measurements

    SciTech Connect

    Terada, Y.; Tanida, H.; Uruga, T.; Takeuchi, A.; Suzuki, Y.; Goto, S.

    2011-09-09

    An x-ray microprobe system with total-reflection mirror optics for trace element analysis has been developed at beamline 37XU of SPring-8. To achieve sub-microprobe, a spatial filter has been installed downstream of a monochromator. Focusing tests have been performed in the x-ray energy range of 6-14 keV. A focused beam size of 0.83 {mu}m(V)x1.35 {mu}m(H) has been obtained at an x-ray energy of 10 keV, and using a spatial filter in the horizontal direction, the beam size is down to 0.84 {mu}m. Micro-x-ray absorption fine structure (XAFS) spectroscopy of submicrometer particles has been done by utilizing the total-reflection mirror optics. It was clearly observed from the nickel K-edge XAFS spectra that the oxidation state of nickel was a mixture of metal and oxide even in the single submicrometer particle.

  1. Spatial nonlinear optics anisotropy and directional growth of TbCOB crystal by micro-pulling-down for SHG application

    NASA Astrophysics Data System (ADS)

    Yuan, Dongsheng; Li, Yang; Shu, Jun; Gao, Zeliang; Jia, Zhitai; Wang, Zhengping; Tao, Xutang

    2016-01-01

    Towards the spatial optimum phase matching (PM) crystal device through a novel way, the micro-pulling-down (μ-PD) technique was used for crystal growth along second-order harmonic generation (SHG) direction for the first time to the best of our knowledge. In this paper, the spatial distribution of |deff| for a potential nonlinear optical (NLO) crystal TbCa4O(BO3)3 (TbCOB) at 1064 nm was calculated and analyzed firstly, and the PM angle (113°, 46°) was found to possess the largest deff value (type-I) being on the order of 1.39 pm/V. Along the optimum SHG direction, a rod-shape TbCOB crystal with 3 mm in diameter was successfully grown by using the μ-PD method. After simple cutting and polishing of the ends for μ-PD grown crystal, a high SHG efficiency (single-pass light reached up to 57%) was realized through a Nd:YAG pico-second laser at 1064 nm, which was comparable to that of crystal samples from Czochralski (Cz) growth. TbCOB crystals also exhibit a high laser damage threshold of >15 GW/cm2.

  2. The influence of spatial pulsed magnetic field application on neuropathic pain after tibial nerve transection in rat.

    PubMed

    Szajkowski, Sebastian; Marcol, Wiesław; Właszczuk, Adam; Cieślar, Grzegorz; Pietrucha-Dutczak, Marita; Sieroń, Aleksander; Lewin-Kowalik, Joanna

    2014-01-01

    The purpose of the study was to examine the influence of the spatial variable magnetic field (induction: 150-300 µT, 80-150 µT, 20-80 µT; frequency 40 Hz) on neuropathic pain after tibial nerve transection. The experiments were carried out on 64 male Wistar C rats. The exposure of animals to magnetic field was performed 1 d/20 min., 5 d/week, for 28 d. Behavioural tests assessing the intensity of allodynia and sensitivity to mechanical and thermal stimuli were conducted 1 d prior to surgery and 3, 7, 14, 21 and 28 d after the surgery. The extent of autotomy was examined. Histological and immunohistochemical analysis was performed. The use of extremely low-frequency magnetic fields of minimal induction values (20-80 µT/40 Hz) decreased pain in rats after nerve transection. The nociceptive sensitivity of healthy rats was not changed following the exposition to the spatial magnetic field of the low frequency. The results of histological and immunohistochemical investigations confirm those findings. Our results indicate that extremely low-frequency magnetic field may be useful in the neuropathic pain therapy. PMID:23781991

  3. Achievements of the DOT-NASA Joint Program on Remote Sensing and Spatial Information Technologies: Application to Multimodal Transportation

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This report presents three-year accomplishments from the national program on Commercial Remote Sensing and Geospatial Technology (CRSGT) application to transportation, administered by the U.S. Department of Transportation (U.S. DOT) in collaboration with the National Aeronautics and Space Administration (NASA). The joint program was authorized under Section 5113 of the Transportation Equity Act for the 21st Century (TEA-21). This is the first national program of its type focusing on transportation applications of emerging commercial remote sensing technologies. U.S. DOT's Research and Special Programs Administration manages the program in coordination with NASA's Earth Science Enterprise's application programs. The program focuses on applications of CRSGT products and systems for providing smarter and more efficient transportation operations and services. The program is performed in partnership with four major National Consortia for Remote Sensing in Transportation (NCRST). Each consortium focuses on research and development of products in one of the four priority areas for transportation application, and includes technical application and demonstration projects carried out in partnership with industries and service providers in their respective areas. The report identifies products and accomplishments from each of the four consortia in meeting the goal of providing smarter and more efficient transportation services. The products and results emerging from the program are being implemented in transportation operations and services through state and local agencies. The Environmental Assessment and Application Consortium (NCRST-E) provides leadership for developing and deploying cost effective environmental and transportation planning services, and integrates CRSGT advances for achieving smarter and cost effective corridor planning. The Infrastructure Management Consortium (NCRST-I) provides leadership in technologies that achieve smarter and cheaper ways of managing

  4. Approximate message-passing with spatially coupled structured operators, with applications to compressed sensing and sparse superposition codes

    NASA Astrophysics Data System (ADS)

    Barbier, Jean; Schülke, Christophe; Krzakala, Florent

    2015-05-01

    We study the behavior of approximate message-passing (AMP), a solver for linear sparse estimation problems such as compressed sensing, when the i.i.d matrices—for which it has been specifically designed—are replaced by structured operators, such as Fourier and Hadamard ones. We show empirically that after proper randomization, the structure of the operators does not significantly affect the performances of the solver. Furthermore, for some specially designed spatially coupled operators, this allows a computationally fast and memory efficient reconstruction in compressed sensing up to the information-theoretical limit. We also show how this approach can be applied to sparse superposition codes, allowing the AMP decoder to perform at large rates for moderate block length.

  5. Changes in fine-root production, phenology and spatial distribution in response to N application in irrigated sweet cherry trees.

    PubMed

    Artacho, Pamela; Bonomelli, Claudia

    2016-05-01

    Factors regulating fine-root growth are poorly understood, particularly in fruit tree species. In this context, the effects of N addition on the temporal and spatial distribution of fine-root growth and on the fine-root turnover were assessed in irrigated sweet cherry trees. The influence of other exogenous and endogenous factors was also examined. The rhizotron technique was used to measure the length-based fine-root growth in trees fertilized at two N rates (0 and 60 kg ha(-1)), and the above-ground growth, leaf net assimilation, and air and soil variables were simultaneously monitored. N fertilization exerted a basal effect throughout the season, changing the magnitude, temporal patterns and spatial distribution of fine-root production and mortality. Specifically, N addition enhanced the total fine-root production by increasing rates and extending the production period. On average, N-fertilized trees had a length-based production that was 110-180% higher than in control trees, depending on growing season. Mortality was proportional to production, but turnover rates were inconsistently affected. Root production and mortality was homogeneously distributed in the soil profile of N-fertilized trees while control trees had 70-80% of the total fine-root production and mortality concentrated below 50 cm depth. Root mortality rates were associated with soil temperature and water content. In contrast, root production rates were primarily under endogenous control, specifically through source-sink relationships, which in turn were affected by N supply through changes in leaf photosynthetic level. Therefore, exogenous and endogenous factors interacted to control the fine-root dynamics of irrigated sweet cherry trees. PMID:26888890

  6. Data-driven spatial b value estimation with applications to California seismicity: To b or not to b

    NASA Astrophysics Data System (ADS)

    Kamer, Yavor; Hiemer, Stefan

    2015-07-01

    In this paper we present a penalized likelihood-based method for spatial estimation of Gutenberg-Richter's b value. Our method incorporates a nonarbitrary partitioning scheme based on Voronoi tessellation, which allows for the optimal partitioning of space using a minimum number of free parameters. By random placement of an increasing number of Voronoi nodes, we are able to explore the whole solution space in terms of model complexity. We obtain an overall likelihood for each model by estimating the b values in all Voronoi regions and calculating its joint likelihood using Aki's formula. Accounting for the number of free parameters, we then calculate the Bayesian Information Criterion for all random realizations. We investigate the ensemble of the best performing models and demonstrate the robustness and validity of our method through extensive synthetic tests. We apply our method to the seismicity of California using two different time spans of the Advanced National Seismic System catalog (1984-2014 and 2004-2014). The results show that for the last decade, the b value variation in the well-instrumented parts of mainland California is limited to the range of (0.94 ± 0.04-1.15 ± 0.06). Apart from the Geysers region, the observed variation can be explained by network-related discrepancies in the magnitude estimations. Our results suggest that previously reported spatial b value variations obtained using classical fixed radius or nearest neighbor methods are likely to have been overestimated, mainly due to subjective parameter choices. We envision that the likelihood-based model selection criteria used in this study can be a useful tool for generating improved earthquake forecasting models.

  7. Spatial Displays and Spatial Instruments

    NASA Technical Reports Server (NTRS)

    Ellis, Stephen R. (Editor); Kaiser, Mary K. (Editor); Grunwald, Arthur J. (Editor)

    1989-01-01

    The conference proceedings topics are divided into two main areas: (1) issues of spatial and picture perception raised by graphical electronic displays of spatial information; and (2) design questions raised by the practical experience of designers actually defining new spatial instruments for use in new aircraft and spacecraft. Each topic is considered from both a theoretical and an applied direction. Emphasis is placed on discussion of phenomena and determination of design principles.

  8. Spatial localization of Langmuir waves generated from an electron beam propagating in an inhomogeneous plasma: Applications to the solar wind

    NASA Astrophysics Data System (ADS)

    Zaslavsky, A.; Volokitin, A. S.; Krasnoselskikh, V. V.; Maksimovic, M.; Bale, S. D.

    2010-08-01

    It is known from in situ observations that large-amplitude spatially localized Langmuir waves are frequent in the solar wind, and usually correlated with the presence of suprathermal electron beams, during type III events or close to the electron foreshock. It seems that the influence of the solar wind density fluctuations on the propagation effects of the Langmuir waves play an important role in the formation of these wave packets. In this article, we focus on the mechanism of generation of localized wave packets by electron beams propagating in an inhomogeneous medium. To this purpose, we present a theoretical model based on the resolution of the high-frequency component of the Zakharov's equation in which a source term describing the electron beam has been introduced, and show that this model is able to reproduce classical results about beam plasma instability and wave trapping in density cavities. Then we present simulation results of the generation of Langmuir wave packets in typical solar wind conditions at 1 A.U., and discuss the origin and nature of their localization.

  9. Application of Serological Tools and Spatial Analysis to Investigate Malaria Transmission Dynamics in Highland Areas of Southwest Uganda

    PubMed Central

    Lynch, Caroline A.; Cook, Jackie; Nanyunja, Sarah; Bruce, Jane; Bhasin, Amit; Drakeley, Chris; Roper, Cally; Pearce, Richard; Rwakimari, John B.; Abeku, Tarekegn A.; Corran, Patrick; Cox, Jonathan

    2016-01-01

    Serological markers, combined with spatial analysis, offer a comparatively more sensitive means by which to measure and detect foci of malaria transmission in highland areas than traditional malariometric indicators. Plasmodium falciparum parasite prevalence, seroprevalence, and seroconversion rate to P. falciparum merozoite surface protein-119 (MSP-119) were measured in a cross-sectional survey to determine differences in transmission between altitudinal strata. Clusters of P. falciparum parasite prevalence and high antibody responses to MSP-119 were detected and compared. Results show that P. falciparum prevalence and seroprevalence generally decreased with increasing altitude. However, transmission was heterogeneous with hotspots of prevalence and/or seroprevalence detected in both highland and highland fringe altitudes, including a serological hotspot at 2,200 m. Results demonstrate that seroprevalence can be used as an additional tool to identify hotspots of malaria transmission that might be difficult to detect using traditional cross-sectional parasite surveys or through vector studies. Our study findings identify ways in which malaria prevention and control can be more effectively targeted in highland or low transmission areas via serological measures. These tools will become increasingly important for countries with an elimination agenda and/or where malaria transmission is becoming patchy and focal, but receptivity to malaria transmission remains high. PMID:27022156

  10. The spatial-temporal variations in optical properties of atmosphere aerosols over China and its application in remote sensing

    NASA Astrophysics Data System (ADS)

    Chen, H.; Cheng, T.

    2013-12-01

    The atmospheric and climate response to the aerosol forcing are assessed by climate models regionally and globally under the past, present and future conditions. However, large uncertainties exist because of incomplete knowledge concerning the distribution and the physical and chemical properties of aerosols as well as aerosol-cloud interactions. Reduction in these uncertainties requires long-term monitoring of detailed properties of different aerosol types. China is one of the heavily polluted areas with high concentration of aerosols in the world. The complex source, composition of China aerosol led to the worse accuracy of aerosol radiative forcing assessment in the world, which urgently calls for improvements on the understanding of China regional aerosol properties. The spatial-temporal properties of aerosol types over China are studied using the radiance measurements and inversions data at 4 Aerosol Robotic Network (AERONET) stations. Five aerosol classes were identified including a coarse-size dominated aerosol type (presumably dust) and four fine-sized dominated aerosol types ranging from non-absorbing to highly absorbing fine aerosols. The mean optical properties of different aerosol types in China and their seasonal variations were also investigated. Based on the cluster analysis, the improved ground-based aerosol model is applied to the MODIS dark target inversion algorithm. Validation with MODIS official product and CE318 is also included.

  11. Spatial grain size sorting in eolian ripples and estimation of wind conditions on planetary surfaces: Application to Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Jerolmack, Douglas J.; Mohrig, David; Grotzinger, John P.; Fike, David A.; Watters, Wesley A.

    2006-05-01

    The landscape seen by the Mars Exploration Rover (MER) Opportunity at Meridiani Planum is dominated by eolian (wind-blown) ripples with concentrated surface lags of hematitic spherules and fragments. These ripples exhibit profound spatial grain size sorting, with well-sorted coarse-grained crests and poorly sorted, generally finer-grained troughs. These ripples were the most common bed form encountered by Opportunity in its traverse from Eagle Crater to Endurance Crater. Field measurements from White Sands National Monument, New Mexico, show that such coarse-grained ripples form by the different transport modes of coarse- and fine-grain fractions. On the basis of our field study, and simple theoretical and experimental considerations, we show how surface deposits of coarse-grained ripples can be used to place tight constraints on formative wind conditions on planetary surfaces. Activation of Meridiani Planum coarse-grained ripples requires a wind velocity of 70 m/s (at a reference elevation of 1 m above the bed). From images by the Mars Orbiter Camera (MOC) of reversing dust streaks, we estimate that modern surface winds reach a velocity of at least 40 m/s and hence may occasionally activate these ripples. The presence of hematite at Meridiani Planum is ultimately related to formation of concretions during aqueous diagenesis in groundwater environments; however, the eolian concentration of these durable particles may have led to the recognition from orbit of this environmentally significant landing site.

  12. Spectroscopic imaging and spatial localization using adiabatic pulses and applications to detect transmural metabolite distribution in the canine heart.

    PubMed

    Robitaille, P M; Merkle, H; Sublett, E; Hendrich, K; Lew, B; Path, G; From, A H; Bache, R J; Garwood, M; Uğurbil, K

    1989-04-01

    Adiabatic pulses have been employed in spectroscopic imaging and relaxation rate measurements at 4.7 T to demonstrate the feasibility of obtaining spectroscopic data from the complete sensitive volume of a surface coil using the surface coil as a transmitter and receiver. With conventional B1 sensitive pulses, spectroscopic localization or imaging techniques, such as chemical-shift imaging, yield resonance intensities that are distorted severely as a function of space, and maximal signal is detected from a small region within the complete sensitive volume of the coil. With adiabatic pulses, however, this problem is eliminated completely. In addition, a new method of spatial localization is introduced. This method, referred to as FLAX-ISIS, is a derivative of longitudinally modulated Fourier series window and ISIS approaches and utilizes adiabatic inversion and excitation pulses. The method allows construction of localized spectra for multiple regions along the surface coil axis by postacquisition data manipulation of a single set of free induction decays. These techniques were applied to the study of the myocardium using an implanted surface coil in an instrumented closed-chest canine model and in an open-chest preparation. The results demonstrate that one-dimensional techniques are adequate for transmural detection of metabolites provided signal origin is restricted to a column perpendicular to the left ventricle wall. PMID:2755331

  13. Application of Serological Tools and Spatial Analysis to Investigate Malaria Transmission Dynamics in Highland Areas of Southwest Uganda.

    PubMed

    Lynch, Caroline A; Cook, Jackie; Nanyunja, Sarah; Bruce, Jane; Bhasin, Amit; Drakeley, Chris; Roper, Cally; Pearce, Richard; Rwakimari, John B; Abeku, Tarekegn A; Corran, Patrick; Cox, Jonathan

    2016-06-01

    Serological markers, combined with spatial analysis, offer a comparatively more sensitive means by which to measure and detect foci of malaria transmission in highland areas than traditional malariometric indicators. Plasmodium falciparum parasite prevalence, seroprevalence, and seroconversion rate to P. falciparum merozoite surface protein-119 (MSP-119) were measured in a cross-sectional survey to determine differences in transmission between altitudinal strata. Clusters of P. falciparum parasite prevalence and high antibody responses to MSP-119 were detected and compared. Results show that P. falciparum prevalence and seroprevalence generally decreased with increasing altitude. However, transmission was heterogeneous with hotspots of prevalence and/or seroprevalence detected in both highland and highland fringe altitudes, including a serological hotspot at 2,200 m. Results demonstrate that seroprevalence can be used as an additional tool to identify hotspots of malaria transmission that might be difficult to detect using traditional cross-sectional parasite surveys or through vector studies. Our study findings identify ways in which malaria prevention and control can be more effectively targeted in highland or low transmission areas via serological measures. These tools will become increasingly important for countries with an elimination agenda and/or where malaria transmission is becoming patchy and focal, but receptivity to malaria transmission remains high. PMID:27022156

  14. Spatial distribution of the electrical conductivity in highly filled polymers: Experiment, modeling, and application to bipolar plates

    NASA Astrophysics Data System (ADS)

    Planes, E.; Gloaguen, F.; Albérola, N.; Flandin, L.

    2013-12-01

    A large variety of composites for electrical applications are developed worldwide on a daily basis. Most of these materials are made from carbonaceous fillers dispersed in polymers. The optimization of the formulations is complex and depends on parameters that are difficult to identify ab initio. The results might also be very sensitive to the processing conditions. There is therefore a need for a fast and accurate method to measure the electrical properties of samples with unfamiliar geometric features and without altering their shape. A four point probes method is incremented that fulfills all the above mentioned requirements. An analytical model is proposed that extends Uhlirs theory and permits to quickly determine the resistivity distribution. Experimental and theoretical approaches were performed to validate the method. An example is proposed with the measurement of samples initially designed for fuel cell-bipolar plates-application.

  15. An inventory of the emission of ammonia from agricultural fertilizer application in China for 2010 and its high-resolution spatial distribution

    NASA Astrophysics Data System (ADS)

    Xu, Peng; Zhang, Yisheng; Gong, Weiwei; Hou, Xikang; Kroeze, Carolien; Gao, Wei; Luan, Shengji

    2015-08-01

    In an agricultural county like China, agricultural fertilizers are the source of ammonia (NH3) emissions. However, the spatial variability in NH3 emissions is large, and the associated uncertainties affect the reliability of total NH3 emission estimates. In this study, an inventory is presented for NH3 emissions from China's agricultural fertilizer application at the city-level, and on a 1 × 1 km grid for croplands in 2010. We present NH3 emissions by source, the temporal and spatial patterns, and the associated uncertainties. The inventory is based on high-resolution activity data, regional emission factors (EFs) and related parameters that are derived from local studies. We compare our emissions estimates with previous inventories from EDGAR and other studies. The total NH3 emissions from China's agricultural fertilizer is 10.7 (8.9-12.3) TgNH3·yr-1. Livestock manure spreading contributes 47.5% to the total emissions, and synthetic fertilizer use by 41.9%. Rural excrement (5.0%) and cake fertilizer (5.5%) are relatively small sources. The spatial pattern of NH3 emissions from China's agricultural fertilizer were primarily concentrated in the North China Plain, the Songliao Plain, the Huaihe River Basin, the Middle-Lower Yangtze Plain, the Pearl River Delta Plain, the Sichuan Basin, the Tarim basin and the Leizhou Peninsula. Approximately 50% of the emissions are from only 76 cities. Our temporal analysis reveals a clear seasonal pattern in NH3 emissions: highest and lowest emissions are calculated for summer and winter, accounting for 42% and 14% of the total emissions, respectively. Peak emissions are calculated for July (1.7 TgNH3·yr-1) and lowest emissions for January (0.5 TgNH3·yr-1). The emissions are correlated with temperature, planting time and cultivation practices.

  16. The Spatial Distribution of Hepatitis C Virus Infections and Associated Determinants—An Application of a Geographically Weighted Poisson Regression for Evidence-Based Screening Interventions in Hotspots

    PubMed Central

    Kauhl, Boris; Heil, Jeanne; Hoebe, Christian J. P. A.; Schweikart, Jürgen; Krafft, Thomas; Dukers-Muijrers, Nicole H. T. M.

    2015-01-01

    Background Hepatitis C Virus (HCV) infections are a major cause for liver diseases. A large proportion of these infections remain hidden to care due to its mostly asymptomatic nature. Population-based screening and screening targeted on behavioural risk groups had not proven to be effective in revealing these hidden infections. Therefore, more practically applicable approaches to target screenings are necessary. Geographic Information Systems (GIS) and spatial epidemiological methods may provide a more feasible basis for screening interventions through the identification of hotspots as well as demographic and socio-economic determinants. Methods Analysed data included all HCV tests (n = 23,800) performed in the southern area of the Netherlands between 2002–2008. HCV positivity was defined as a positive immunoblot or polymerase chain reaction test. Population data were matched to the geocoded HCV test data. The spatial scan statistic was applied to detect areas with elevated HCV risk. We applied global regression models to determine associations between population-based determinants and HCV risk. Geographically weighted Poisson regression models were then constructed to determine local differences of the association between HCV risk and population-based determinants. Results HCV prevalence varied geographically and clustered in urban areas. The main population at risk were middle-aged males, non-western immigrants and divorced persons. Socio-economic determinants consisted of one-person households, persons with low income and mean property value. However, the association between HCV risk and demographic as well as socio-economic determinants displayed strong regional and intra-urban differences. Discussion The detection of local hotspots in our study may serve as a basis for prioritization of areas for future targeted interventions. Demographic and socio-economic determinants associated with HCV risk show regional differences underlining that a one

  17. Discovering fuzzy spatial association rules

    NASA Astrophysics Data System (ADS)

    Kacar, Esen; Cicekli, Nihan K.

    2002-03-01

    Discovering interesting, implicit knowledge and general relationships in geographic information databases is very important to understand and use these spatial data. One of the methods for discovering this implicit knowledge is mining spatial association rules. A spatial association rule is a rule indicating certain association relationships among a set of spatial and possibly non-spatial predicates. In the mining process, data is organized in a hierarchical manner. However, in real-world applications it may not be possible to construct a crisp structure for this data, instead some fuzzy structures should be used. Fuzziness, i.e. partial belonging of an item to more than one sub-item in the hierarchy, could be applied to the data itself, and also to the hierarchy of spatial relations. This paper shows that, strong association rules can be mined from large spatial databases using fuzzy concept and spatial relation hierarchies.

  18. Inorganic nanoparticles for the spatial and temporal control of organic reactions: Applications to radical degradation of biopolymer networks

    NASA Astrophysics Data System (ADS)

    Walker, Joan Marie

    Nanoparticles of gold and iron oxide not only possess remarkable optical and magnetic properties, respectively, but are also capable of influencing their local environment with an astounding degree of precision. Using nanoparticles to direct the reactivity of organic molecules near their surface provides a unique method of spatial and temporal control. Enediynes represent an exceptional class of compounds that are thermally reactive to produce a diradical intermediate via Bergman cycloaromatization. While natural product enediynes are famously cytotoxic, a rich chemistry of synthetic enediynes has developed utilizing creative means to control this reactivity through structure, electronics, metal chelation, and external triggering mechanisms. In a heretofore unexplored arena for Bergman cyclization, we have investigated the reactivity of enediynes in connection with inorganic nanoparticles in which the physical properties of the nanomaterial are directly excited to thermally promote aromatization. As the first example of this methodology, gold nanoparticles conjugated with (Z)-octa-4-en-2,6-diyne-1,8-dithiol were excited with 514 nm laser irradiation. The formation of aromatic and polymeric products was confirmed through Raman spectroscopy and electron microscopy. Water soluble analogues Au-PEG-EDDA and Fe3O4-PEG-EDDA (EDDA = (Z)-octa-4-en-2,6-diyne-1,8-diamine) show similar reactivity under laser irradiation or alternating magnetic field excitation, respectively. Furthermore, we have used these functionalized nanoparticles to attack proteinaceous substrates including fibrin and extracellular matrix proteins, capitalizing on the ability of diradicals to disrupt peptidic bonds. By delivering a locally high payload of reactive molecules and thermal energy to the large biopolymer, network restructuring and collapse is achieved. As a synthetic extension towards multifunctional nanoparticles, noble metal seed-decorated iron oxides have also been prepared and assessed for

  19. Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe₃O₄ nanoparticles for biomedical applications.

    PubMed

    Sadat, M E; Patel, Ronak; Sookoor, Jason; Bud'ko, Sergey L; Ewing, Rodney C; Zhang, Jiaming; Xu, Hong; Wang, Yilong; Pauletti, Giovanni M; Mast, David B; Shi, Donglu

    2014-09-01

    In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe3O4) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe3O4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent ~10nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe3O4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe3O4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems. PMID:25063092

  20. Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe3O4 nanoparticles for biomedical applications

    SciTech Connect

    Sadat, M E; Patel, Ronak; Sookoor, Jason; Bud'ko, Sergey L; Ewing, Rodney C; Zhang, Jiaming; Xu, Hong; Wang, Yilong; Pauletti, Giovanni M; Mast, David B; Shi, Donglu

    2014-09-01

    In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe3O4) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe3O4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent ~10nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe3O4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe3O4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems.

  1. Chapter J: Issues and challenges in the application of geostatistics and spatial-data analysis to the characterization of sand-and-gravel resources

    USGS Publications Warehouse

    Hack, Daniel R.

    2005-01-01

    Sand-and-gravel (aggregate) resources are a critical component of the Nation's infrastructure, yet aggregate-mining technologies lag far behind those of metalliferous mining and other sectors. Deposit-evaluation and site-characterization methodologies are antiquated, and few serious studies of the potential applications of spatial-data analysis and geostatistics have been published. However, because of commodity usage and the necessary proximity of a mine to end use, aggregate-resource exploration and evaluation differ fundamentally from comparable activities for metalliferous ores. Acceptable practices, therefore, can reflect this cruder scale. The increasing use of computer technologies is colliding with the need for sand-and-gravel mines to modernize and improve their overall efficiency of exploration, mine planning, scheduling, automation, and other operations. The emergence of megaquarries in the 21st century will also be a contributing factor. Preliminary research into the practical applications of exploratory-data analysis (EDA) have been promising. For example, EDA was used to develop a linear-regression equation to forecast freeze-thaw durability from absorption values for Lower Paleozoic carbonate rocks mined for crushed aggregate from quarries in Oklahoma. Applications of EDA within a spatial context, a method of spatial-data analysis, have also been promising, as with the investigation of undeveloped sand-and-gravel resources in the sedimentary deposits of Pleistocene Lake Bonneville, Utah. Formal geostatistical investigations of sand-and-gravel deposits are quite rare, and the primary focus of those studies that have been completed is on the spatial characterization of deposit thickness and its subsequent effect on ore reserves. A thorough investigation of a gravel deposit in an active aggregate-mining area in central Essex, U.K., emphasized the problems inherent in the geostatistical characterization of particle-size-analysis data. Beyond such factors

  2. Development of high-spatial and high-mass resolution mass spectrometric imaging (MSI) and its application to the study of small metabolites and endogenous molecules of plants

    SciTech Connect

    Jun, Ji Hyun

    2012-01-01

    High-spatial and high-mass resolution laser desorption ionization (LDI) mass spectrometric (MS) imaging technology was developed for the attainment of MS images of higher quality containing more information on the relevant cellular and molecular biology in unprecedented depth. The distribution of plant metabolites is asymmetric throughout the cells and tissues, and therefore the increase in the spatial resolution was pursued to reveal the localization of plant metabolites at the cellular level by MS imaging. For achieving high-spatial resolution, the laser beam size was reduced by utilizing an optical fiber with small core diameter (25 μm) in a vacuum matrix-assisted laser desorption ionization-linear ion trap (vMALDI-LTQ) mass spectrometer. Matrix application was greatly improved using oscillating capillary nebulizer. As a result, single cell level spatial resolution of ~ 12 μm was achieved. MS imaging at this high spatial resolution was directly applied to a whole Arabidopsis flower and the substructures of an anther and single pollen grains at the stigma and anther were successfully visualized. MS imaging of high spatial resolution was also demonstrated to the secondary roots of Arabidopsis thaliana and a high degree of localization of detected metabolites was successfully unveiled. This was the first MS imaging on the root for molecular species. MS imaging with high mass resolution was also achieved by utilizing the LTQ-Orbitrap mass spectrometer for the direct identification of the surface metabolites on the Arabidopsis stem and root and differentiation of isobaric ions having the same nominal mass with no need of tandem mass spectrometry (MS/MS). MS imaging at high-spatial and high-mass resolution was also applied to cer1 mutant of the model system Arabidopsis thaliana to demonstrate its usefulness in biological studies and reveal associated metabolite changes in terms of spatial distribution and/or abundances compared to those of wild-type. The spatial

  3. Investigation of detailed spatial structure of the Moscow urban heat island with application of the newest meteorological observations and regional climate modelling

    NASA Astrophysics Data System (ADS)

    Varentsov, Mikhail; Pavel, Konstantinov; Timofey, Samsonov

    2016-04-01

    During the last years, the network of metrological observation in Moscow megacity and its neighborhoods, forming the biggest urban agglomeration in Europe, was significantly extended. Several new weather stations and completely new dense network of air-quality monitoring appears during the last decade. In addition, several microwave meteorological profilers MTP 5, which are available to measure temperature at the heights from 0 to 1000 meters with 50-m resolution, were installed in the city and its surrounding. All these measurements allow revealing undiscovered features of Moscow urban climate and urban heat island (UHI). In our research, bases on this data, we covered several topics related to urban climatology: - Investigation of detailed spatial structure of Moscow UHI and its relationships with building features, such as land use and morphology of the street canyons, obtained by GIS-algorithms according (Samsonov et. al, 2015); - Investigation of three-dimensional structure of the UHI, including its vertical extend and influence on the stratification of the atmosphere, and three-dimensional structure of the urban heat island advection and urban heat plumes; - Application of the newest data for validation of the regional climate model COSMO-CLM, coupled with TEB urban scheme (Masson, 2000; Trusilova et. al., 2013), launched for Moscow region with 1-km spatial resolution. References: 1. Masson V. A. Physically-Based Scheme for the Urban Energy Budget in Atmospheric models. Bound. Layer Meteor. 2000. V. 94 (3). P. 357-397. 2. Trusilova K., Früh B., Brienen S., Walter A., Masson V., Pigeon G., Becker P. Implementation of an Urban Parameterization Scheme into the Regional Climate Model COSMO-CLM. J. Appl. Meteor. Climatol. V. 52. P. 2296-2311. 3. Samsonov T.E., Konstantinov P.I., Varentsov M.I. Object-oriented approach to urban canyon analysis and its applications in meteorological modeling. Urban Climate. 2015. Vol. 13. P. 122-139.

  4. Spatial and Temporal Analysis of Human Movements and Applications for Disaster Response Management Utilizing Cell Phone Usage Data

    NASA Astrophysics Data System (ADS)

    Yasumiishi, M.; Renschler, C. S.; Bittner, T. E.

    2015-07-01

    As cell phone usage becomes a norm in our daily lives, analysis and application of the data has become part of various research fields. This study focuses on the application of cell phone usage data to disaster response management. Cell phones work as a communication link between emergency responders and victims during and after a major disaster. This study recognizes that there are two kinds of disasters, one with an advance warning, and one without an advance warning. Different movement distance between a day with a blizzard (advanced warning) and a normal weather day was identified. In the scenario of a day with an extreme event without advanced warning (earthquake), factors that alter the phone users' movements were analyzed. Lastly, combining both cases, a conceptual model of human movement factors is proposed. Human movements consist of four factors that are push factors, movement-altering factors, derived attributes and constraint factors. Considering each category of factors in case of emergency, it should be necessary that we prepare different kinds of emergency response plans depending on the characteristics of a disaster.

  5. Application of an imputation method for geospatial inventory of forest structural attributes across multiple spatial scales in the Lake States, U.S.A

    NASA Astrophysics Data System (ADS)

    Deo, Ram K.

    Credible spatial information characterizing the structure and site quality of forests is critical to sustainable forest management and planning, especially given the increasing demands and threats to forest products and services. Forest managers and planners are required to evaluate forest conditions over a broad range of scales, contingent on operational or reporting requirements. Traditionally, forest inventory estimates are generated via a design-based approach that involves generalizing sample plot measurements to characterize an unknown population across a larger area of interest. However, field plot measurements are costly and as a consequence spatial coverage is limited. Remote sensing technologies have shown remarkable success in augmenting limited sample plot data to generate stand- and landscape-level spatial predictions of forest inventory attributes. Further enhancement of forest inventory approaches that couple field measurements with cutting edge remotely sensed and geospatial datasets are essential to sustainable forest management. We evaluated a novel Random Forest based k Nearest Neighbors (RF-kNN) imputation approach to couple remote sensing and geospatial data with field inventory collected by different sampling methods to generate forest inventory information across large spatial extents. The forest inventory data collected by the FIA program of US Forest Service was integrated with optical remote sensing and other geospatial datasets to produce biomass distribution maps for a part of the Lake States and species-specific site index maps for the entire Lake State. Targeting small-area application of the state-of-art remote sensing, LiDAR (light detection and ranging) data was integrated with the field data collected by an inexpensive method, called variable plot sampling, in the Ford Forest of Michigan Tech to derive standing volume map in a cost-effective way. The outputs of the RF-kNN imputation were compared with independent validation

  6. The application of line imaging velocimetry to provide high resolution spatially resolved velocity data in plate impact experiments

    NASA Astrophysics Data System (ADS)

    Philpott, M. K.; George, A.; Whiteman, G.; De'Ath, J.; Millett, J. C. F.

    2015-12-01

    A single streak camera line imaging velocimeter has been applied to Armco® iron plate impact experiments to study material response at the grain scale. The grain size and phase distribution were determined with electron back scatter diffraction. The optical system resolution and fringe size were optimised to suit the grain size distribution. Comparisons of the performance and merits of several analysis algorithms including the ‘Fourier transform’, ‘fringe tracking’, ‘quadrature’ and the ‘continuous wavelet transform’ have been made by application to synthetic data. Point heterodyne velocimetry measurements made at the same location on the target surface have been compared with the line imaging velocimetry data for confirmation.

  7. Example Applications of A Physically-Based 3D Surface-Subsurface Hydrologic Model Over Multiple Spatial and Temporal Scales

    NASA Astrophysics Data System (ADS)

    Sudicky, E. A.; Park, Y. J.; Hwang, H. T.; Berg, S.; Frey, S.

    2014-12-01

    It is now generally accepted within the scientific community that the climate is changing, and that future climate change may have significant impact on water resources in both quantity and quality. Alterations of base flow to rivers due to changing subsurface flow patterns, fluctuations in soil moisture and in the depth of the groundwater table, water levels in lakes and wetlands, and altered groundwater recharge/discharge patterns are examples of possible consequences of future climate change. In this presentation, our physically-based model, HydroGeoSphere (HGS), is first briefly described. It is a physically-based 3D control-volume finite element model representing 2D surface water flow and transport on the land surface together with 3D variably-saturated flow and transport in the subsurface. A globally implicit scheme used to solve the nonlinear surface and subsurface flow and transport equations simultaneously. The model can explicitly account for the hydrologic, solute and thermal interactions between surface and subsurface flow regimes as well as the atmospheric inputs in terms of air temperature, solar radiation and sensible/latent heat fluxes. A parallel computational framework has been implemented to facilitate model applications in high performance computing environments. The applicability of the model is demonstrated for a variety of problems, covering the hill slope scale to improve the understanding of the physical and chemical processes in the water cycle, to the assessment of the impact of climate change on water resources over the Canadian landmass in three dimensions. The climate-driven 3D basin-scale examples range from that of a highly characterized watershed in Southern Ontario having an area of about 7000 km2 to a large basin in Western Canada that covers an area of about 120,000 km2. The continental scale simulations explore the impacts of global climate change on Canada's surface and groundwater resources.

  8. Part 3. Modeling of Multipollutant Profiles and Spatially Varying Health Effects with Applications to Indicators of Adverse Birth Outcomes.

    PubMed

    Molitor, John; Coker, Eric; Jerrett, Michael; Ritz, Beate; Li, Arthur

    2016-04-01

    obtained by the estimation process generally yields smaller standard errors while inconsistent clustering is generally associated with larger errors. These multivariate methods are applied to a range of different problems related to air pollution exposures, namely an association of multipollutant profiles with indicators of poverty and to an assessment of the association between measures of various air pollutants, patterns of socioeconomic status (SES), and birth outcomes. All of these studies involve an examination of regional-level exposures, at the census tract (CT) and census block group (CBG) levels, and individual-level outcomes throughout Los Angeles (LA) County. Results indicate that effects of pollutants vary spatially and vary in a complex interconnected manner that cannot be discerned using standard additive line ar models. Results obtaine d from these studies can be used to efficiently use limited resources to inform policies in targeting are as where air pollution reductions result in maximum health benefits. PMID:27459845

  9. Application of knowledge-driven spatial modelling approaches and uncertainty management to a study of Rift Valley fever in Africa

    PubMed Central

    Clements, Archie CA; Pfeiffer, Dirk U; Martin, Vincent

    2006-01-01

    Background There are few studies that have investigated uncertainties surrounding the scientific community's knowledge of the geographical distribution of major animal diseases. This is particularly relevant to Rift Valley fever (RVF), a zoonotic disease causing destructive outbreaks in livestock and man, as the geographical range of the disease is widening to involve previously unaffected regions. In the current study we investigate the application of methods developed in the decision sciences: multiple criteria decision making using weighted linear combination and ordered weighted averages, and Dempster-Shafer theory, implemented within the geographical information system IDRISI, to obtain a greater understanding of uncertainty related to the geographical distribution of RVF. The focus is on presenting alternate methods where extensive field data are not available and traditional, model-based approaches to disease mapping are impossible to conduct. Results Using a compensatory multiple criteria decision making model based on weighted linear combination, most of sub-Saharan Africa was suitable for endemic circulation of RVF. In contrast, areas where rivers and lakes traversed semi-arid regions, such as those bordering the Sahara, were highly suitable for RVF epidemics and wet, tropical areas of central Africa had low suitability. Using a moderately non-compensatory model based on ordered weighted averages, the areas considered suitable for endemic and epidemic RVF were more restricted. Varying the relative weights of the different factors in the models did not affect suitability estimates to a large degree, but variations in model structure had a large impact on our suitability estimates. Our Dempster-Shafer analysis supported the belief that a range of semi-arid areas were suitable for RVF epidemics and the plausibility that many other areas of the continent were suitable. Areas where high levels of uncertainty were highlighted included the Ethiopian Highlands

  10. Repeated application of Modafinil and Levodopa reveals a drug-independent precise timing of spatial working memory modulation.

    PubMed

    Bezu, M; Shanmugasundaram, B; Lubec, G; Korz, V

    2016-10-01

    Cognition enhancing drugs often target the dopaminergic system, which is involved in learning and memory, including working memory that in turn involves mainly the prefrontal cortex and the hippocampus. In most animal models for modulations of working memory animals are pre-trained to a certain criterion and treated then acutely to test drugs effects on working memory. Thus, little is known regarding subchronic or chronic application of cognition enhancing drugs and working memory performance. Therefore we trained male rats over six days in a rewarded alternation test in a T-maze. Rats received daily injections of either modafinil or Levodopa (L-Dopa) at a lower and a higher dose 30min before training. Levodopa but not modafinil increased working memory performance during early training significantly at day 3 when compared to vehicle controls. Both drugs induced dose dependent differences in working memory with significantly better performance at low doses compared to high doses for modafinil, in contrast to L-Dopa where high dose treated rats performed better than low dose rats. Strikingly, these effects appeared only at day 3 for both drugs, followed by a decline in behavioral performance. Thus, a critical drug independent time window for dopaminergic effects upon working memory could be revealed. Evaluating the underlying mechanisms contributes to the understanding of temporal effects of dopamine on working memory performance. PMID:27268456

  11. Elucidating the impact of nitrate and labile carbon application on spatial heterogeneity of denitrification by 15N modelling

    NASA Astrophysics Data System (ADS)

    Cardenas, Laura; Loick, Nadine; Dixon, Liz; Matthews, Peter; Gilsanz, Claudia; Bol, Roland; Lewicka-Szczebak, Dominika; Well, Reinhard

    2016-04-01

    N2O is considered to be an important GHG with soils representing its major source and accounting for approximately 6% of the current global warming and is also implicated in the depletion of stratospheric ozone. The atmospheric N2O concentration has been increasing since the Industrial Revolution making the understanding of its sources and removal processes very important for development of mitigation strategies. Bergstermann et al. (2011) found evidence of the existence of more than one pool of nitrate undergoing denitrification in a silty clay loam arable soil amended with glucose/nitrate solution. The Rayleigh type model was used to simulate d15N of N2O using process rates and associated fractionation factors, but assumptions for some of the model parameters had to be made due to lack of available data. In this study we carried out 2 incubation experiments in order to parameterise the model. To restrict the volume of soil reached by the amendment, we used blocks containing 3 soil cores that were incubated in one vessel to measure emissions of NO, N2O, N2 and CO2 from a clay grassland soil amended with KNO3 (N) and glucose (C) in three treatments: '1C' only 1 core received N and C (the other 2 received water), '3C' 3 cores received N and C, and 'Control' (received water only). The results showed changes in the d15Nbulk trends after day 6 post amendment application, coinciding with the decrease of N2O fluxes. We also report the results in the 15N site preference (SP) and d18O. We will show the results from the model validation based on this data.

  12. Applicability of the single equivalent point dipole model to represent a spatially distributed bio-electrical source

    NASA Technical Reports Server (NTRS)

    Armoundas, A. A.; Feldman, A. B.; Sherman, D. A.; Cohen, R. J.

    2001-01-01

    Although the single equivalent point dipole model has been used to represent well-localised bio-electrical sources, in realistic situations the source is distributed. Consequently, position estimates of point dipoles determined by inverse algorithms suffer from systematic error due to the non-exact applicability of the inverse model. In realistic situations, this systematic error cannot be avoided, a limitation that is independent of the complexity of the torso model used. This study quantitatively investigates the intrinsic limitations in the assignment of a location to the equivalent dipole due to distributed electrical source. To simulate arrhythmic activity in the heart, a model of a wave of depolarisation spreading from a focal source over the surface of a spherical shell is used. The activity is represented by a sequence of concentric belt sources (obtained by slicing the shell with a sequence of parallel plane pairs), with constant dipole moment per unit length (circumferentially) directed parallel to the propagation direction. The distributed source is represented by N dipoles at equal arc lengths along the belt. The sum of the dipole potentials is calculated at predefined electrode locations. The inverse problem involves finding a single equivalent point dipole that best reproduces the electrode potentials due to the distributed source. The inverse problem is implemented by minimising the chi2 per degree of freedom. It is found that the trajectory traced by the equivalent dipole is sensitive to the location of the spherical shell relative to the fixed electrodes. It is shown that this trajectory does not coincide with the sequence of geometrical centres of the consecutive belt sources. For distributed sources within a bounded spherical medium, displaced from the sphere's centre by 40% of the sphere's radius, it is found that the error in the equivalent dipole location varies from 3 to 20% for sources with size between 5 and 50% of the sphere's radius

  13. A spatial analysis of cultural ecosystem service valuation by regional stakeholders in Florida: a coastal application of the social values for ecosystem services (SolVES) tool

    USGS Publications Warehouse

    Coffin, Alisa W.; Swett, Robert A.; Cole, Zachary D.

    2012-01-01

    Livelihoods and lifestyles of people throughout the world depend on essential goods and services provided by marine and coastal ecosystems. However, as societal demand increases and available ocean and coastal space diminish, better methods are needed to spatially and temporally allocate ocean and coastal activities such as shipping, energy production, tourism, and fishing. While economic valuation is an important mechanism for doing so, cultural ecosystem services often do not lend themselves to this method. Researchers from the U.S. Geological Survey are working collaboratively with the Florida Sea Grant College Program to map nonmonetary values of cultural ecosystem services for a pilot area (Sarasota Bay) in the Gulf of Mexico. The research seeks to close knowledge gaps about the attitudes and perceptions, or nonmonetary values, held by coastal residents toward cultural ecosystem services, and to adapt related, terrestrial-based research methods to a coastal setting. A critical goal is to integrate research results with coastal and marine spatial planning applications, thus making them relevant to coastal planners and managers in their daily efforts to sustainably manage coastal resources. Using information about the attitudes and preferences of people toward places and uses in the landscape, collected from value and preference surveys, the USGS SolVES 2.0 tool will provide quantitative models to relate social values, or perceived nonmonetary values, assigned to locations by survey respondents with the underlying environmental characteristics of those same locations. Project results will increase scientific and geographic knowledge of how Sarasota Bay residents value their area’s cultural ecosystem services.

  14. Development of a statistical model to identify spatial and meteorological drivers of elevated O3 in Nevada and its application to other rural mountainous regions.

    PubMed

    Fine, Rebekka; Miller, Matthieu B; Gustin, Mae Sexauer

    2015-10-15

    Measurements of O3 at relatively remote monitoring sites are useful for quantifying baseline O3, and subsequently the magnitude of O3 not controllable by local regulations. As the National Ambient Air Quality Standard (NAAQS) for O3 becomes more stringent, there is an increased need to quantify baseline O3 particularly in the Western US, where regional and global sources can significantly enhance O3 measured at surface sites, yielding baseline mixing ratios approaching or exceeding the NAAQS threshold. Past work has indicated that meteorological conditions as well as site specific spatial characteristics (e.g. elevation, basin size, gradient) are significantly correlated with O3 intercepted at rural monitoring sites. Here, we use 3 years of measurements from sites throughout rural Nevada to develop a categorical tree model to identify spatial and meteorological characteristics that are associated with elevated baseline O3. Data from other sites in the Intermountain Western US are used to test the applicability of the model for sites throughout the region. Our analyses indicate that increased elevation and basin size were associated with increased frequency of elevated O3. On a daily time scale, relative humidity had the strongest association with observed MDA8 O3. Seventy-four percent of MDA8 O3 observations>60 ppbv occurred when daily minimum relative humidity was <15%. Further, we found that including ancillary pollutant data did not improve the predictive accuracy for measurements >60 ppbv whereas including upper air meteorological measurements improved the accuracy of predicting periods when O3 was >60 ppbv. These findings indicate that transport, rather than local production, influences O3 measurements in Nevada, and that high elevation sites in rural Nevada, are representative of baseline conditions in the Intermountain Western US. PMID:25895623

  15. Spatial networks

    NASA Astrophysics Data System (ADS)

    Barthélemy, Marc

    2011-02-01

    Complex systems are very often organized under the form of networks where nodes and edges are embedded in space. Transportation and mobility networks, Internet, mobile phone networks, power grids, social and contact networks, and neural networks, are all examples where space is relevant and where topology alone does not contain all the information. Characterizing and understanding the structure and the evolution of spatial networks is thus crucial for many different fields, ranging from urbanism to epidemiology. An important consequence of space on networks is that there is a cost associated with the length of edges which in turn has dramatic effects on the topological structure of these networks. We will thoroughly explain the current state of our understanding of how the spatial constraints affect the structure and properties of these networks. We will review the most recent empirical observations and the most important models of spatial networks. We will also discuss various processes which take place on these spatial networks, such as phase transitions, random walks, synchronization, navigation, resilience, and disease spread.

  16. Planetary Spatial Analyst

    NASA Technical Reports Server (NTRS)

    Keely, Leslie

    2008-01-01

    This is a status report for the project entitled Planetary Spatial Analyst (PSA). This report covers activities from the project inception on October 1, 2007 to June 1, 2008. Originally a three year proposal, PSA was awarded funding for one year and required a revised work statement and budget. At the time of this writing the project is well on track both for completion of work as well as budget. The revised project focused on two objectives: build a solid connection with the target community and implement a prototype software application that provides 3D visualization and spatial analysis technologies for that community. Progress has been made for both of these objectives.

  17. Spatially Extended Modelocking

    NASA Technical Reports Server (NTRS)

    Fork, Richard L.; Diffey, William M.; Gamble, Lisa; Keys, Andrew S.

    1999-01-01

    We examine the properties of optical fields that are extended in space over transverse dimensions of several meters or more in terms of both multiple spatial modes and also multiple temporal modes. We focus attention on the task of producing and maintaining well defined phase relationships for the set of spatial and temporal modes. In particular, we address operating regimes where the optical fields are not confined within an optical resonator, but still have well defined phase relations through the use of optical field sensing and correction techniques. Special applications of interest occur in safe beaming of optical power and in approaching optical intensities capable of producing nonlinear phenomena in the vacuum.

  18. Temporal and Spatial Expression of TGF-b1 in the Early Phase of Patellar Tendon Healing after Application of Platelet Rich Plasma

    PubMed Central

    Lyras, Dimitris N.; Kazakos, Konstantinos; Tilkeridis, Konstantinos; Kokka, Anna; Ververidis, Athanasios; Botaitis, Sotirios; Agrogiannis, George

    2016-01-01

    Background: The aim of this study is to find out the spatial and temporal expression of TGF-b1 during the tendon healing, after application of Platelet Rich Plasma (PRP). Methods: A patellar tendon defect model in rabbits was used for this purpose. 48 skeletally mature New Zealand White rabbits, weighing 3.5 kg, were used for this study. Equal numbers of animals from both groups were sacrificed at 4 different time points (1st, 2nd, 3rd, and 4th week). A full thickness patellar tendon substance in the right limb of each animal was excised from its central portion during the operation. PRP with a gel form was applied and filled the tendon defect in PRP group. No PRP was applied in the tendon defect of controls. Histological sections with hematoxylin-eosin and immunohistochemical sections with an anti-TGF-b1 primary antibody were made for the evaluation of the results. Results: A differentiation of the healing process was observed in the PRP group in comparison with the control group. TGF-b1 expression was detected in various cell populations (inflammatory cells, endothelial cells, macrophages, and tenocytes). Both cytoplasmic and nuclear expressions were present. The larger amounts of immunoexpression were localized in epitenon and in the repair site. PRP group showed stronger and more extensive staining at 1st and 2nd week (P<0.0001), whereas control group showed more extensive staining at the 3rd and 4th week (P<0.0001). Conclusions: Our study demonstrates that locally application of PRP result in an alteration of TGF-b1 expression during the healing of a patellar tendon defect. PMID:27200395

  19. Spatial alexia.

    PubMed

    Ardila, A; Rosselli, M

    1994-05-01

    Twenty-one patients with right hemisphere damage were studied (11 men, 10 women; average age = 41.33; range = 19-65). Patients were divided in two groups: pre-Rolandic (six patients) and retro-Rolandic (15 patients) right hemisphere damage. A special reading test was given to each patient. The observed errors included: literal errors (substitutions, additions, and omissions of letters), substitutions of syllables and pseudowords for meaningful words, left hemispatial neglect, confabulation, splitting of words, verbal errors (substitutions, additions, and omission of words), grouping of letters belonging to two different words, misuse of punctuation marks, and errors in following lines. It was proposed that spatial alexia is characterized by: (1) some difficulties in the recognition of the spatial orientation in letters; (2) left hemispatial neglect; (3) tendency to "complete" the sense of words and sentences; (4) inability to follow lines when reading texts, and sequentially explore the spatial distribution of the written material; and (5) grouping and fragmentation of words, most likely as a consequence of the inability to interpret the relative value of spaces between letters correctly. PMID:7960468

  20. Analysing the effect of movement on local survival: a new method with an application to a spatially structured population of the arboreal gecko Gehyra variegata.

    PubMed

    Gruber, Bernd; Henle, Klaus

    2008-01-01

    Mortality during movement between habitat patches is the most obvious cost of dispersal, but rarely it has been demonstrated empirically. An approach is presented, which uses capture-mark-recapture data of an arboreal gecko species to determine the effect of individual movement on local survival in a spatially structured population. Because capture-mark-recapture data are widely available for a range of animal species, it should be possible to extend their application to other species. The method is based on the assumption that the tendency to be a territorial animal or to be a floating animal is fixed during the study period. The advantage of our approach is that only one additional parameter has to be estimated for describing movement risks. We further tested the power of our approach to detect an association of movement and mortality with simulated capture histories. The study revealed a strong negative effect of movement on local survival. Hence, animals that moved more often between trees had a lower survival rate. Interestingly, the mean movement rate for males was significantly higher than for females, which should lead to a biased sex ratio towards females in the population. As there was an even sex ratio in the population, we discuss not mutually exclusive explanations for this finding like differences in emigration rates between sexes, differences in survival rates between sexes, or a skewed sex ratio in offspring. PMID:17938971

  1. 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

  2. Spatially 2D-selective RF excitations using the PROPELLER trajectory: basic principles and application to MR spectroscopy of irregularly shaped single voxel.

    PubMed

    Busch, Martin G; Finsterbusch, Jürgen

    2011-11-01

    Spatially two-dimensional selective radio frequency (2DRF) excitations are able to excite arbitrarily-shaped profiles in their excitation plane and, hence, can be used to minimize partial volume effects in single-voxel magnetic resonance spectroscopy. In this study, 2DRF excitations based on the PROPELLER trajectory which consists of blades of parallel lines that are rotated against each other, are presented. Because the k-space center is covered with each segment, the trajectory yields a high signal efficiency which, e.g., is considerably improved compared to a segmented blipped-planar approach. It is shown that a sampling density correction based on the PROPELLER trajectory's Voronoi diagram suppresses unwanted side excitations. Off-resonance effects like chemical-shift displacement artifacts, can be minimized by applying nonselective refocusing radio frequency pulses between the lines of a blade. With half-Fourier segments, the 2DRF's echo time contribution can be shortened considerably. Thus, robust 2DRF excitations capable of exciting high-resolution profiles at short echo times with high signal efficiency are obtained. Their applicability to MR spectroscopy of an arbitrarily-shaped single voxel is demonstrated in a two-bottle phantom and in the human brain in vivo on a 3 T whole-body MR system. PMID:21465546

  3. Towards spatially distributed flood forecasts in flash flood prone areas: application to the supervision of a road network in the South of France

    NASA Astrophysics Data System (ADS)

    Naulin, Jean-Philippe; Payrastre, Olivier; Gaume, Eric; Delrieu, Guy

    2013-04-01

    Accurate flood forecasts are crucial for an efficient flood event management. Until now, hydro-meteorological forecasts have been mainly used for early-warnings in France (Meteorological and flood vigilance maps) or over the world (Flash-flood guidances). These forecasts are generally limited to the main streams covered by the flood forecasting services or to specific watersheds with particular assets like check dams which are in most cases well gauged river sections, leaving aside large parts of the territory. A distributed hydro-meteorological forecasting approach will be presented, able to take advantage of the high spatial and temporal resolution rainfall estimates that are now available to provide information at ungauged sites. The proposed system aiming at detecting road inundation risks had been initially developed and tested in areas of limited size. Its extension to a whole region (the Gard region in the South of France) will be presented, including over 2000 crossing points between rivers and roads and its validation against a large data set of actually reported road inundations observed during recent flash-flood events. These first validation results appear promising. Such a tool would provide the necessary information for flood event management services to identify the areas at risk and to take the appropriate safety and rescue measures: pre-positioning of rescue means, stopping of the traffic on exposed roads, determination of safe accesses or evacuation routes. Moreover, beyond the specific application to the supervision of a road network, this work provides also results concerning the performances of hydro-meteorological forecasts for ungauged headwaters.

  4. Application of Dempster-Shafer theory, spatial analysis and remote sensing for groundwater potentiality and nitrate pollution analysis in the semi-arid region of Khuzestan, Iran.

    PubMed

    Rahmati, Omid; Melesse, Assefa M

    2016-10-15

    Effective management and sustainable development of groundwater resources of arid and semi-arid environments require monitoring of groundwater quality and quantity. The aim of this paper is to develop a reasonable methodological framework for producing the suitability map for drinking water through the geographic information system, remote sensing and field surveys of the Andimeshk-Dezful, Khozestan province, Iran as a semi-arid region. This study investigated the delineation of groundwater potential zone based on Dempster-Shafer (DS) theory of evidence and evaluate its applicability for groundwater potentiality mapping. The study also analyzed the spatial distribution of groundwater nitrate concentration; and produced the suitability map for drinking water. The study has been carried out with the following steps: i) creation of maps of groundwater conditioning factors; ii) assessment of groundwater occurrence characteristics; iii) creation of groundwater potentiality map (GPM) and model validation; iv) collection and chemical analysis of water samples; v) assessment of groundwater nitrate pollution; and vi) creation of groundwater potentiality and quality map. The performance of the DS was also evaluated using the receiver operating characteristic (ROC) curve method and pumping test data to ensure its generalization ability, which eventually, the GPM showed 87.76% accuracy. The detailed analysis of groundwater potentiality and quality revealed that the 'non acceptable' areas covers an area of about 1479km(2) (60%). The study will provide significant information for groundwater management and exploitation in areas where groundwater is a major source of water and its exploration is critical to support drinking water need. PMID:27358196

  5. Thermodynamic Model of Spatial Memory

    NASA Astrophysics Data System (ADS)

    Kaufman, Miron; Allen, P.

    1998-03-01

    We develop and test a thermodynamic model of spatial memory. Our model is an application of statistical thermodynamics to cognitive science. It is related to applications of the statistical mechanics framework in parallel distributed processes research. Our macroscopic model allows us to evaluate an entropy associated with spatial memory tasks. We find that older adults exhibit higher levels of entropy than younger adults. Thurstone's Law of Categorical Judgment, according to which the discriminal processes along the psychological continuum produced by presentations of a single stimulus are normally distributed, is explained by using a Hooke spring model of spatial memory. We have also analyzed a nonlinear modification of the ideal spring model of spatial memory. This work is supported by NIH/NIA grant AG09282-06.

  6. Fusion and clustering algorithms for spatial data

    NASA Astrophysics Data System (ADS)

    Kuntala, Pavani

    Spatial clustering is an approach for discovering groups of related data points in spatial data. Spatial clustering has attracted a lot of research attention due to various applications where it is needed. It holds practical importance in application domains such as geographic knowledge discovery, sensors, rare disease discovery, astronomy, remote sensing, and so on. The motivation for this work stems from the limitations of the existing spatial clustering methods. In most conventional spatial clustering algorithms, the similarity measurement mainly considers the geometric attributes. However, in many real applications, users are concerned about both the spatial and the non-spatial attributes. In conventional spatial clustering, the input data set is partitioned into several compact regions and data points that are similar to one another in their non-spatial attributes may be scattered over different regions, thus making the corresponding objective difficult to achieve. In this dissertation, a novel clustering methodology is proposed to explore the clustering problem within both spatial and non-spatial domains by employing a fusion-based approach. The goal is to optimize a given objective function in the spatial domain, while satisfying the constraint specified in the non- spatial attribute domain. Several experiments are conducted to provide insights into the proposed methodology. The algorithm first captures the spatial cores having the highest structure and then employs an iterative, heuristic mechanism to find the optimal number of spatial cores and non-spatial clusters that exist in the data. Such a fusion-based framework allows for the handling of data streams and provides a framework for comparing spatial clusters. The correctness and efficiency of the proposed clustering model is demonstrated on real world and synthetic data sets.

  7. Development of a spatially universal framework for classifying stream assemblages with application to conservation planning for Great Lakes lotic fish communities

    USGS Publications Warehouse

    McKenna, James E., Jr.; Schaeffer, Jeffrey S.; Stewart, Jana S.; Slattery, Michael T.

    2015-01-01

    Classifications are typically specific to particular issues or areas, leading to patchworks of subjectively defined spatial units. Stream conservation is hindered by the lack of a universal habitat classification system and would benefit from an independent hydrology-guided spatial framework of units encompassing all aquatic habitats at multiple spatial scales within large regions. We present a system that explicitly separates the spatial framework from any particular classification developed from the framework. The framework was constructed from landscape variables that are hydrologically and biologically relevant, covered all space within the study area, and was nested hierarchically and spatially related at scales ranging from the stream reach to the entire region; classifications may be developed from any subset of the 9 basins, 107 watersheds, 459 subwatersheds, or 10,000s of valley segments or stream reaches. To illustrate the advantages of this approach, we developed a fish-guided classification generated from a framework for the Great Lakes region that produced a mosaic of habitat units which, when aggregated, formed larger patches of more general conditions at progressively broader spatial scales. We identified greater than 1,200 distinct fish habitat types at the valley segment scale, most of which were rare. Comparisons of biodiversity and species assemblages are easily examined at any scale. This system can identify and quantify habitat types, evaluate habitat quality for conservation and/or restoration, and assist managers and policymakers with prioritization of protection and restoration efforts. Similar spatial frameworks and habitat classifications can be developed for any organism in any riverine ecosystem.

  8. Spatial Manipulation with Microfluidics

    PubMed Central

    Lin, Benjamin; Levchenko, Andre

    2015-01-01

    Biochemical gradients convey information through space, time, and concentration, and are ultimately capable of spatially resolving distinct cellular phenotypes, such as differentiation, proliferation, and migration. How these gradients develop, evolve, and function during development, homeostasis, and various disease states is a subject of intense interest across a variety of disciplines. Microfluidic technologies have become essential tools for investigating gradient sensing in vitro due to their ability to precisely manipulate fluids on demand in well-controlled environments at cellular length scales. This review will highlight their utility for studying gradient sensing along with relevant applications to biology. PMID:25905100

  9. Spatial manipulation with microfluidics.

    PubMed

    Lin, Benjamin; Levchenko, Andre

    2015-01-01

    Biochemical gradients convey information through space, time, and concentration, and are ultimately capable of spatially resolving distinct cellular phenotypes, such as differentiation, proliferation, and migration. How these gradients develop, evolve, and function during development, homeostasis, and various disease states is a subject of intense interest across a variety of disciplines. Microfluidic technologies have become essential tools for investigating gradient sensing in vitro due to their ability to precisely manipulate fluids on demand in well-controlled environments at cellular length scales. This review will highlight their utility for studying gradient sensing along with relevant applications to biology. PMID:25905100

  10. SMART: A Spatially Explicit Bio-Economic Model for Assessing and Managing Demersal Fisheries, with an Application to Italian Trawlers in the Strait of Sicily

    PubMed Central

    Russo, Tommaso; Parisi, Antonio; Garofalo, Germana; Gristina, Michele; Cataudella, Stefano; Fiorentino, Fabio

    2014-01-01

    Management of catches, effort and exploitation pattern are considered the most effective measures to control fishing mortality and ultimately ensure productivity and sustainability of fisheries. Despite the growing concerns about the spatial dimension of fisheries, the distribution of resources and fishing effort in space is seldom considered in assessment and management processes. Here we propose SMART (Spatial MAnagement of demersal Resources for Trawl fisheries), a tool for assessing bio-economic feedback in different management scenarios. SMART combines information from different tasks gathered within the European Data Collection Framework on fisheries and is composed of: 1) spatial models of fishing effort, environmental characteristics and distribution of demersal resources; 2) an Artificial Neural Network which captures the relationships among these aspects in a spatially explicit way and uses them to predict resources abundances; 3) a deterministic module which analyzes the size structure of catches and the associated revenues, according to different spatially-based management scenarios. SMART is applied to demersal fishery in the Strait of Sicily, one of the most productive fisheries of the Mediterranean Sea. Three of the main target species are used as proxies for the whole range exploited by trawlers. After training, SMART is used to evaluate different management scenarios, including spatial closures, using a simulation approach that mimics the recent exploitation patterns. Results evidence good model performance, with a noteworthy coherence and reliability of outputs for the different components. Among others, the main finding is that a partial improvement in resource conditions can be achieved by means of nursery closures, even if the overall fishing effort in the area remains stable. Accordingly, a series of strategically designed areas of trawling closures could significantly improve the resource conditions of demersal fisheries in the Strait of

  11. Geographic Information Systems and Libraries: Patrons, Maps, and Spatial Information. Papers presented at the Clinic on Library Applications of Data Processing (Champaign, Illinois, April 10-12, 1995).

    ERIC Educational Resources Information Center

    Smith, Linda C., Ed.; Gluck, Myke, Ed.

    This document assembles conference papers which focus on how electronic technologies are creating new ways of meeting user needs for spatial and cartographic information. Contents include: (1) "Mapping Technology in Transition" (Mark Monmonier); (2) "Cataloging Planetospatial Data in Digital Form: Old Wine, New Bottles--New Wine, Old Bottles"…

  12. A component-based, integrated spatially distributed hydrologic/water quality model: AgroEcoSystem-Watershed (AgES-W) overview and application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    AgroEcoSystem-Watershed (AgES-W) is a modular, Java-based spatially distributed model which implements hydrologic/water quality simulation components. The AgES-W model was previously evaluated for streamflow and recently has been enhanced with the addition of nitrogen (N) and sediment modeling compo...

  13. A Bayesian mixed shrinkage prior procedure for spatial-stochastic basis selection and evaluation of gPC expansions: Applications to elliptic SPDEs

    NASA Astrophysics Data System (ADS)

    Karagiannis, Georgios; Konomi, Bledar A.; Lin, Guang

    2015-03-01

    We propose a new fully Bayesian method to efficiently obtain the spectral representation of a spatial random field, which can conduct spatial-stochastic basis selection and evaluation of generalized Polynomial Chaos (gPC) expansions when the number of the available basis functions is significantly larger than the size of the training data-set. We develop a fully Bayesian stochastic procedure, called mixed shrinkage prior (MSP), which performs both basis selection and coefficient evaluation simultaneously. MSP involves assigning a prior probability to the gPC structure and assigning conjugate priors to the expansion coefficients that can be thought of as mixtures of Ridge-LASSO shrinkage priors, in augmented form. The method offers a number of advantages over existing compressive sensing methods in gPC literature, such that it recovers possible sparse structures in both stochastic and spatial domains while the resulting expansion can be re-used directly to economically obtain results at any spatial input values. Yet, it inherits all the advantages of Bayesian model uncertainty methods, e.g. accounts for uncertainty about basis significance and provides interval estimation through posterior distributions. A unique highlight of the MSP procedure is that it can address heterogeneous sparsity in the spatial domain for different random dimensions. Furthermore, it yields a compromise between Ridge and LASSO regressions, and hence combines a weak (l2-norm) and strong (l1-norm) shrinkage, in an adaptive, data-driven manner. We demonstrate the good performance of the proposed method, and compare it against other existing compressive sensing ones on elliptic stochastic partial differential equations.

  14. Geostatistical Modeling of the Spatial Distribution of Soil Dioxins in the Vicinity of an Incinerator. 1. Theory and Application to Midland, Michigan

    PubMed Central

    Goovaerts, Pierre; Trinh, Hoa T.; Demond, Avery; Franzblau, Alfred; Garabrant, David; Gillespie, Brenda; Lepkowski, James; Adriaens, Peter

    2008-01-01

    Deposition of pollutants around point sources of contamination, such as incinerators, can display complex spatial patterns depending on prevailing weather conditions, the local topography and the characteristics of the source. Deterministic dispersion models often fail to capture the complexity observed in the field, resulting in uncertain predictions that might hamper subsequent decision-making, such as delineation of areas targeted for additional sampling or remediation. This paper describes a geostatistical simulation-based methodology that combines the detailed process-based modeling of atmospheric deposition from an incinerator with the probabilistic modeling of residual variability of field samples. The approach is used to delineate areas with high level of dioxin TEQDF-WHO98 (Toxic Equivalents) around an incinerator, accounting for 53 field data and the output of the EPA Industrial Source Complex (ISC3) dispersion model. The dispersion model explains 43.7% of the variance in soil TEQ data, while the regression residuals are spatially correlated with a range of 776 meters. One hundred realizations of soil TEQ values are simulated on a grid with a 50 meter spacing. The benefit of stochastic simulation over spatial interpolation is twofold: 1) maps of simulated point TEQ values can easily be aggregated to the geography that is the most relevant for decision making (e.g. census block, ZIP codes); and 2) the uncertainty at the larger scale is simply modeled by the empirical distribution of block-averaged simulated values. Incorporating the output of the atmospheric deposition model as spatial trend yields a more realistic prediction of the spatial distribution of TEQ value than lognormal kriging using only the field data, in particular in sparsely sampled areas away from the incinerator. The geostatistical model provided guidance for the study design (census block-based population sampling) of the University of Michigan Dioxin Exposure Study (UMDES), focused on

  15. Alternative spatial configurations to reflect landscape structure in a hydrological model: SUMMA applications to the Reynolds Creek Watershed and the Columbia River Basin

    NASA Astrophysics Data System (ADS)

    Nijssen, Bart; Clark, Martyn; Mizukami, Naoki; Chegwidden, Oriana

    2016-04-01

    Most existing hydrological models use a fixed representation of landscape structure. For example, high-resolution, spatially-distributed models may use grid cells that exchange moisture through the saturated subsurface or may divide the landscape into hydrologic response units that only exchange moisture through surface channels. Alternatively, many regional models represent the landscape through coarse elements that do not model any moisture exchange between these model elements. These spatial organizations are often represented at a low-level in the model code and its data structures, which makes it difficult to evaluate different landscape representations using the same hydrological model. Instead, such experimentation requires the use of multiple, different hydrological models, which in turn complicates the analysis, because differences in model outcomes are no longer constrained by differing spatial representations. This inflexibility in the representation of landscape structure also limits a model's capability for scaling local processes to regional outcomes. In this study, we used the Structure for Unifying Multiple Modeling Alternatives (SUMMA) to evaluate different model spatial configurations to represent landscape structure and to evaluate scaling behavior. SUMMA can represent the moisture exchange between arbitrarily shaped landscape elements in a number of different ways, while using the same model parameterizations for vertical fluxes. This allows us to isolate the effects of changes in landscape representations on modeled hydrological fluxes and states. We examine the effects of spatial configuration in Reynolds Creek, Idaho, USA, which is a research watershed with gaged areas from 1-20 km2. We then use the same modeling system to evaluate scaling behavior in simulated hydrological fluxes in the Columbia River Basin, Pacific Northwest, USA. This basin drains more than 500,000 km2 and includes the Reynolds Creek Watershed.

  16. Spatial Encounters: Exercises in Spatial Awareness.

    ERIC Educational Resources Information Center

    New Mexico Univ., Albuquerque.

    This series of activities on spatial relationships was designed to help users acquire the skills of spatial visualization and orientation and to improve their effectiveness in applying those skills. The series contains an introduction to spatial orientation with several self-directed activities to help improve that skill. It also contains seven…

  17. Mathematical Modeling of spatial disease variables by Spatial Fuzzy Logic for Spatial Decision Support Systems

    NASA Astrophysics Data System (ADS)

    Platz, M.; Rapp, J.; Groessler, M.; Niehaus, E.; Babu, A.; Soman, B.

    2014-11-01

    A Spatial Decision Support System (SDSS) provides support for decision makers and should not be viewed as replacing human intelligence with machines. Therefore it is reasonable that decision makers are able to use a feature to analyze the provided spatial decision support in detail to crosscheck the digital support of the SDSS with their own expertise. Spatial decision support is based on risk and resource maps in a Geographic Information System (GIS) with relevant layers e.g. environmental, health and socio-economic data. Spatial fuzzy logic allows the representation of spatial properties with a value of truth in the range between 0 and 1. Decision makers can refer to the visualization of the spatial truth of single risk variables of a disease. Spatial fuzzy logic rules that support the allocation of limited resources according to risk can be evaluated with measure theory on topological spaces, which allows to visualize the applicability of this rules as well in a map. Our paper is based on the concept of a spatial fuzzy logic on topological spaces that contributes to the development of an adaptive Early Warning And Response System (EWARS) providing decision support for the current or future spatial distribution of a disease. It supports the decision maker in testing interventions based on available resources and apply risk mitigation strategies and provide guidance tailored to the geo-location of the user via mobile devices. The software component of the system would be based on open source software and the software developed during this project will also be in the open source domain, so that an open community can build on the results and tailor further work to regional or international requirements and constraints. A freely available EWARS Spatial Fuzzy Logic Demo was developed wich enables a user to visualize risk and resource maps based on individual data in several data formats.

  18. Combination of remote sensing data products to derive spatial climatologies of "degree days" and downscale meteorological reanalyses: application to the Upper Indus Basin

    NASA Astrophysics Data System (ADS)

    Forsythe, N. D.; Rutter, N.; Brock, B. W.; Fowler, H. J.; Blenkinsop, S.

    2014-12-01

    Lack of observations for the full range of required variables is a critical reason why many cryosphere-dominated hydrological modelling studies adopt a temperature index (degree day) approach to meltwater simulation rather than resolving the full surface energy balance. Thus spatial observations of "degree days" would be extremely useful in constraining model parameterisations. Even for models implementing a full energy balance, "degree day" observations provide a characterisation of the spatial distribution of climate inputs to the cryosphere-hydrological system. This study derives "degree days" for the Upper Indus Basin by merging remote sensing data products: snow cover duration (SCD), from MOD10A1 and land surface temperature (LST), from MOD11A1 and MYD11A1. Pixel-wise "degree days" are calculated, at imagery-dependent spatial resolution, by multiplying SCD by (above-freezing) daily LST. This is coherent with the snowpack-energy-to-runoff conversion used in temperature index algorithms. This allows assessment of the spatial variability of mass inputs (accumulated snowpack) because in nival regime areas - where complete ablation is regularly achieved - mass is the limiting constraint. The GLIMS Randolph Glacier Inventory is used to compare annual totals and seasonal timings of "degree days" over glaciated and nival zones. Terrain-classified statistics (by elevation and aspect) for the MODIS "degree-day" hybrid product are calculated to characterise of spatial precipitation distribution. While MODIS data products provide detailed spatial resolution relative to tributary catchment areas, the limited instrument record length is inadequate for assessing climatic trends and greatly limits use for hydrological model calibration and validation. While multi-decadal MODIS equivalent data products may be developed in the coming years, at present alternative methods are required for "degree day" trend analysis. This study thus investigates the use of the hybrid MODIS

  19. Multi-beam second-harmonic generation in beta barium borate with a spatial light modulator and application to internal structuring in poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Liu, D.; Perrie, W.; Kuang, Z.; Scully, P. J.; Baum, A.; Liang, S.; Edwardson, S. P.; Fearon, E.; Dearden, G.; Watkins, K. G.

    2012-06-01

    Parallel beam frequency doubling of 170 fs, NIR pulses is demonstrated by placing a thin beta barium borate (BBO) nonlinear crystal after a spatial light modulator. Computer-generated holograms applied to the spatial light modulator create 18 parallel diffracted beams at the fundamental wavelength λ=775 nm, then frequency doubled to λ=387 nm and focussed inside the poly(methyl methacrylate) (PMMA) substrate for refractive index structuring. This procedure, demonstrated for the first time in PMMA, requires careful attention to phase matching of multiple beams and opens up dynamic parallel processing at UV wavelengths where nematic liquid crystal devices are more sensitive to optical damage. By overlapping filamentary modifications, an efficient, stable volume phase grating with dimensions 5×5×2.0 mm3 and pitch Λ=15 μm was fabricated in 18 minutes and reached a first-order diffraction efficiency of 70 % at the Bragg angle.

  20. Experimental demonstration of an intensity minimum at the focus of a laser beam created by spatial coherence: application to the optical trapping of dielectric particles.

    PubMed

    Raghunathan, Shreyas B; van Dijk, Thomas; Peterman, Erwin J G; Visser, Taco D

    2010-12-15

    In trying to manipulate the intensity distribution of a focused field, one typically uses amplitude or phase masks. Here we explore an approach, namely, varying the state of spatial coherence of the incident field. We experimentally demonstrate that the focusing of a Bessel-correlated beam produces an intensity minimum at the geometric focus rather than a maximum. By varying the spatial coherence width of the field, which can be achieved by merely changing the size of an iris, it is possible to change this minimum into a maximum in a continuous manner. This method can be used, for example, in novel optical trapping schemes, to selectively manipulate particles with either a low or high index of refraction. PMID:21165125

  1. Quantifying spatial patterns and timescales of fine sediment redistribution in river basins: application of a sediment budget model with fallout radionuclide tracers

    NASA Astrophysics Data System (ADS)

    Smith, Hugh; Blake, William; Taylor, Alex

    2013-04-01

    Improved understanding of fine sediment and associated contaminant redistribution within river basins requires information on the sources and rates of sediment supply alongside the timescales of downstream sediment transfer. Sediment budgets are an effective tool for examining these patterns. While small, intensively monitored research catchments may provide such information, the examination of larger scale patterns of sediment transfer often requires the use of modelling-based approaches. Furthermore, knowledge of timescales of fine sediment transfer in river basins is limited. Few studies link sediment budgets with explicit information on the residence or travel times of fine sediment. This information is essential for understanding contemporary patterns of river basin sediment redistribution, and has implications for predicting possible recovery times of rivers affected by contaminated sediment from historic or recent pollution. Against this background, we aim to quantify the spatial patterns and timescales of suspended sediment transfer through a river basin (917 km2) situated in south-west England. We apply a spatially-distributed sediment budget model (SedNet) in conjunction with high-resolution spatial data and long-term rainfall and river flow measurements. Model outputs provide an indication of mean annual patterns of sediment redistribution and yields, which were computed for three land cover surveys. This modelling was coupled with techniques for estimating fine sediment residence times, which are based on differences in the decay rates of three fallout radionuclides (Be-7, excess Pb-210 and Cs-137). Findings from this study demonstrate the need for more integrated approaches to better understand spatial patterns and timescales of sediment redistribution in river basins.

  2. A geostatistical framework for quantifying the reach-scale spatial structure of river morphology: 2. Application to restored and natural channels

    NASA Astrophysics Data System (ADS)

    Legleiter, Carl J.

    2014-01-01

    Alluvial rivers are shaped by interactions between the bed topography, the flow field, and the movement of sediment. To help refine our understanding of these connections between form and process, I developed a geostatistical framework for quantifying the reach-scale spatial structure of river morphology, described in a companion paper. In this study, I applied this approach to a restored channel and three disparate reaches of a dynamic, natural stream. Repeat topographic surveys of each site were used to examine relationships between channel change and the variability and organization of the topography. For the restored river, the development of point bars increased overall morphologic diversity, primarily because of greater cross-sectional asymmetry. The three natural reaches experienced a variety of adjustments ranging from 1) gradual bar growth and bank erosion to; 2) extensive deposition followed by channel abandonment; and 3) chute cutoff and incision of a new channel. In both the restored and natural streams, geostatistical analysis, which involved variogram modeling, calculation of integral metrics, and inspection of variogram maps, provided an effective, informative summary of the observed channel changes. The use of dimensionless variables accounted for channel size, highlighted differences in spatial structure, and enabled a comparison among sites — the restored reach had not yet achieved the same degree of heterogeneity as the more pristine channels. Emphasizing variability and spatial pattern via this geostatistical framework could yield insight on form-process interactions and help to quantify geomorphic complexity and habitat heterogeneity in the applied context of river restoration.

  3. Spatial analysis of soybean canopy response to soybean cyst nematodes (Heterodera glycines) in eastern Arkansas: An approach to future precision agriculture technology application

    NASA Astrophysics Data System (ADS)

    Kulkarni, Subodh

    2008-10-01

    Heterodera glycines Ichinohe, commonly known as soybean cyst nematode (SCN) is a serious widespread pathogen of soybean in the US. Present research primarily investigated feasibility of detecting SCN infestation in the field using aerial images and ground level spectrometric sensing. Non-spatial and spatial linear regression analyses were performed to correlate SCN population densities with Normalized Difference Vegetation Index (NDVI) and Green NDVI (GNDVI) derived from soybean canopy spectra. Field data were obtained from two fields; Field A and B under different nematode control strategies in 2003 and 2004. Analysis of aerial image data from July 18, 2004 from the Field A showed a significant relationship between SCN population at planting and the GNDVI (R2=0.17 at p=0.0006). Linear regression analysis revealed that SCN had a little effect on yield (R2 =0.14, at p=0.0001, RMSEP=1052.42 kg ha-1) and GNDVI (R 2=0.17 at p=0.0006, RMSEP=0.087) derived from the aerial imagery on a single date. However, the spatial regression analysis based on spherical semivariogram showed that the RMSEP was 0.037 for the GNDVI on July 18, 2004 and 427.32 kg ha-1 for yield on October 14, 2003 indicating better model performance. For July 18, 2004 data from Field B, a relationship between NDVI and the cyst counts at planting was significant (R2=0.5 at p=0.0468). Non-spatial analyses of the ground level spectrometric data for the first field showed that NDVI and GNDVI were correlated with cyst counts at planting (R 2=0.34 and 0.27 at p=0.0015 and 0.0127, respectively), and GNDVI was correlated with eggs count at planting (R2= 0.27 at p=0.0118). Both NDVI and GNDVI were correlated with egg counts at flowering (R 2=0.34 and 0.27 at p=0.0013 and 0.0018, respectively). However, paired T test to validate the above relationships showed that, predicted values of NDVI and GNDVI were significantly different. The statistical evidences suggested that variability in vegetation indices was caused

  4. SOLAP technology: Merging business intelligence with geospatial technology for interactive spatio-temporal exploration and analysis of data

    NASA Astrophysics Data System (ADS)

    Rivest, Sonia; Bédard, Yvan; Proulx, Marie-Josée; Nadeau, Martin; Hubert, Frederic; Pastor, Julien

    To support their analytical processes, today's organizations deploy data warehouses and client tools such as OLAP (On-Line Analytical Processing) to access, visualize, and analyze their integrated, aggregated and summarized data. Since a large part of these data have a spatial component, better client tools are required to take full advantage of the geometry of the spatial phenomena or objects being analyzed. With this regard, Spatial OLAP (SOLAP) technology offers promising possibilities. A SOLAP tool can be defined as "a type of software that allows rapid and easy navigation within spatial databases and that offers many levels of information granularity, many themes, many epochs and many display modes synchronized or not: maps, tables and diagrams" [Bédard, Y., Proulx, M.J., Rivest, S., 2005. Enrichissement du OLAP pour l'analyse géographique: exemples de réalisation et différentes possibilités technologiques. In: Bentayeb, F., Boussaid, O., Darmont, J., Rabaseda, S. (Eds.), Entrepôts de Données et Analyse en ligne, RNTI B_1. Paris: Cépaduès, pp. 1-20]. SOLAP tools offer a new user interface and are meant to be client applications sitting on top of multi-scale spatial data warehouses or datacubes. As they are based on the multidimensional paradigm, they facilitate the interactive spatio-temporal exploration of data. The purpose of this paper is to discuss how SOLAP concepts support spatio-temporal exploration of data and then to present the geovisualization, interactivity, and animation features of the SOLAP software developed by our research group. This paper first reviews the general concepts behind OLAP and SOLAP systems. This is followed by a discussion of how these SOLAP concepts support spatio-temporal exploration of data. In the subsequent section, SOLAP software is introduced along with features that enable geovisualization, interactivity and animation.

  5. Spatial attention systems in spatial neglect.

    PubMed

    Karnath, Hans-Otto

    2015-08-01

    It has been established that processes relating to 'spatial attention' are implemented at cortical level by goal-directed (top-down) and stimulus-driven (bottom-up) networks. Spatial neglect in brain-damaged individuals has been interpreted as a distinguished exemplar for a disturbance of these processes. The present paper elaborates this assumption. Functioning of the two attentional networks seem to dissociate in spatial neglect; behavioral studies of patients' orienting and exploration behavior point to a disturbed stimulus-driven but preserved goal-directed attention system. When a target suddenly appears somewhere in space, neglect patients demonstrate disturbed detection and orienting if it is located in contralesional direction. In contrast, if neglect patients explore a scene with voluntarily, top-down controlled shifts of spatial attention, they perform movements that are oriented into all spatial directions without any direction-specific disturbances. The paper thus argues that not the top-down control of spatial attention itself, rather a body-related matrix on top of which this process is executed, seems affected. In that sense, the traditional role of spatial neglect as a stroke model for 'spatial attention' requires adjustment. Beyond its insights into the human stimulus-driven attentional system, the disorder most notably provides vistas in how our brain encodes topographical information and organizes spatially oriented action - including the top-down control of spatial attention - in relation to body position. PMID:26004064

  6. Spatial-Operator Algebra For Robotic Manipulators

    NASA Technical Reports Server (NTRS)

    Rodriguez, Guillermo; Kreutz, Kenneth K.; Milman, Mark H.

    1991-01-01

    Report discusses spatial-operator algebra developed in recent studies of mathematical modeling, control, and design of trajectories of robotic manipulators. Provides succinct representation of mathematically complicated interactions among multiple joints and links of manipulator, thereby relieving analyst of most of tedium of detailed algebraic manipulations. Presents analytical formulation of spatial-operator algebra, describes some specific applications, summarizes current research, and discusses implementation of spatial-operator algebra in the Ada programming language.

  7. Approximate spatial reasoning

    NASA Technical Reports Server (NTRS)

    Dutta, Soumitra

    1988-01-01

    A model for approximate spatial reasoning using fuzzy logic to represent the uncertainty in the environment is presented. Algorithms are developed which can be used to reason about spatial information expressed in the form of approximate linguistic descriptions similar to the kind of spatial information processed by humans. Particular attention is given to static spatial reasoning.

  8. A compute-Efficient Bitmap Compression Index for Database Applications

    SciTech Connect

    Wu, Kesheng; Shoshani, Arie

    2006-01-01

    FastBit: A Compute-Efficient Bitmap Compression Index for Database Applications The Word-Aligned Hybrid (WAH) bitmap compression method and data structure is highly efficient for performing search and retrieval operations on large datasets. The WAH technique is optimized for computational efficiency. The WAH-based bitmap indexing software, called FastBit, is particularly appropriate to infrequently varying databases, including those found in the on-line analytical processing (OLAP) industry. Some commercial database products already include some Version of a bitmap index, which could possibly be replaced by the WAR bitmap compression techniques for potentially large operational speedup. Experimental results show performance improvements by an average factor of 10 over bitmap technology used by industry, as well as increased efficiencies in constructing compressed bitmaps. FastBit can be use as a stand-alone index, or integrated into a database system. ien integrated into a database system, this technique may be particularly useful for real-time business analysis applications. Additional FastRit applications may include efficient real-time exploration of scientific models, such as climate and combustion simulations, to minimize search time for analysis and subsequent data visualization. FastBit was proven theoretically to be time-optimal because it provides a search time proportional to the number of elements selected by the index.

  9. A compute-Efficient Bitmap Compression Index for Database Applications

    Energy Science and Technology Software Center (ESTSC)

    2006-01-01

    FastBit: A Compute-Efficient Bitmap Compression Index for Database Applications The Word-Aligned Hybrid (WAH) bitmap compression method and data structure is highly efficient for performing search and retrieval operations on large datasets. The WAH technique is optimized for computational efficiency. The WAH-based bitmap indexing software, called FastBit, is particularly appropriate to infrequently varying databases, including those found in the on-line analytical processing (OLAP) industry. Some commercial database products already include some Version of a bitmap index,more » which could possibly be replaced by the WAR bitmap compression techniques for potentially large operational speedup. Experimental results show performance improvements by an average factor of 10 over bitmap technology used by industry, as well as increased efficiencies in constructing compressed bitmaps. FastBit can be use as a stand-alone index, or integrated into a database system. ien integrated into a database system, this technique may be particularly useful for real-time business analysis applications. Additional FastRit applications may include efficient real-time exploration of scientific models, such as climate and combustion simulations, to minimize search time for analysis and subsequent data visualization. FastBit was proven theoretically to be time-optimal because it provides a search time proportional to the number of elements selected by the index.« less

  10. Application of spatial analysis and multivariate analysis techniques in distribution and source study of polycyclic aromatic hydrocarbons in the topsoil of Beijing, China

    NASA Astrophysics Data System (ADS)

    Wang, Kaiyan; Shen, Yating; Zhang, Shucai; Ye, Youbin; Shen, Qiong; Hu, Jundong; Wang, Xuejun

    2009-01-01

    Surface soil samples were collected from 161 sites throughout the downtown and suburban area of Beijing, China. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) concentrations. Through Kriging analysis, five heavily contaminated zones were identified in the study area. Sources of PAHs in the soil were apportioned using principal factor analysis and multiple linear regression. Three factors were identified representing coal combustion/vehicle emission, coking emission, and petroleum sources, respectively. The relative contributions of the three sources were 48% for coal/vehicle emission, 28% for coking emission, and 24% for petroleum sources. The contributions of total PAHs from the three sources were 16.4, 4.63 and 3.70 ng g-1, respectively. Spatial analysis indicated that the contribution of coal/vehicle sources was higher in the downtown area than in the suburban area, the petroleum sources had a high contribution in the urban area, and the contribution of coking sources was high in the suburban area. The results indicated that PAH contamination in the surface soil in Beijing was closely related to the spatial characteristics of energy consumption and functional zoning. Improvement of the energy consumption structure and relocation of industries with heavy pollution are effective ways to control PAH contamination in surface soil in the area.

  11. Rapid thermal annealing effect on the spatial resistivity distribution of AZO thin films deposited by pulsed-direct-current sputtering for solar cells applications

    NASA Astrophysics Data System (ADS)

    Ayachi, Boubakeur; Aviles, Thomas; Vilcot, Jean-Pierre; Sion, Cathy

    2016-03-01

    Room temperature deposited aluminium-doped zinc oxide thin films on glass substrate, using pulsed-DC magnetron sputtering, have shown high optical transmittance and low electrical resistivity with high uniformity of its spatial distribution after they were exposed to a rapid thermal annealing process at 400 °C under N2H2 atmosphere. It is particularly interesting to note that such an annealing process of AZO thin films for only 30 s was sufficient, on one hand to improve their optical transmittance from 73% to 86%, on the other hand to both decrease their resistivity from 1.7 × 10-3 Ω cm to 5.1 × 10-4 Ω cm and achieve the highest uniformity spatial distribution. To understand the mechanisms behind such improvements of the optoelectronic properties, electrical, optical, structural and morphological changes as a function of annealing time have been investigated by using hall measurement, UV-visible spectrometry, X-ray diffraction and scanning electron microscope imaging, respectively.

  12. Spatial representation of soundscape

    NASA Astrophysics Data System (ADS)

    Boubezari, Mohammed; Bento Coelho, Jos-Luis

    2001-05-01

    For the last 30 years the concept of soundscape has been largely adopted in many scientific disciplines and by the urban experts for the benefit of a better comprehension and management of the sound environment. However, the spatial representation of the soundscape as a simple tool for the description, management or composition of sound environment is always needed. In this article a method is presented for the spatial sound representation with differentiated sources. The first results are shown. This method gives an account of the soundscape as close as possible to the way it can be perceived by the listener in each location. This method generates qualitative sound maps in a reduced urban scale, based on in situ measurements and on the implication of the measuring subject perception. The maps are sufficient enough to isolate many sound sources of the overall sound field. In this manner, sound quality refers to the sound attribute of a perceived object. It is neither an aesthetic judgment nor traditional psychoacoustics criteria. Concrete examples of application to squares in the city of Lisbon will be shown and discussed. The limits and the prospects of such a qualitative representation will also be presented and discussed.

  13. THE SPATIAL AND TEMPORAL DISTRIBUTION OF CHLORPYRIFOS IN THE U.S. EPA INDOOR AIR QUALITY (IAQ) TEST HOUSE FOLLOWING CRACK AND CREVICE TYPE APPLICATIONS

    EPA Science Inventory

    Pesticides found in homes may result from indoor applications to control household pests or by translocation from outdoor sources. Pesticides disperse according to their physical properties and other factors such as human activity, air exchange, temperature and humidity. Insect...

  14. Spatial Standard Observer

    NASA Technical Reports Server (NTRS)

    Watson, Andrw B. (Inventor)

    2010-01-01

    The present invention relates to devices and methods for the measurement and/or for the specification of the perceptual intensity of a visual image. or the perceptual distance between a pair of images. Grayscale test and reference images are processed to produce test and reference luminance images. A luminance filter function is convolved with the reference luminance image to produce a local mean luminance reference image . Test and reference contrast images are produced from the local mean luminance reference image and the test and reference luminance images respectively, followed by application of a contrast sensitivity filter. The resulting images are combined according to mathematical prescriptions to produce a Just Noticeable Difference, JND value, indicative of a Spatial Standard Observer. SSO. Some embodiments include masking functions. window functions. special treatment for images lying on or near border and pre-processing of test images.

  15. Spatial Standard Observer

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B. (Inventor)

    2012-01-01

    The present invention relates to devices and methods for the measurement and/or for the specification of the perceptual intensity of a visual image, or the perceptual distance between a pair of images. Grayscale test and reference images are processed to produce test and reference luminance images. A luminance filter function is convolved with the reference luminance image to produce a local mean luminance reference image. Test and reference contrast images are produced from the local mean luminance reference image and the test and reference luminance images respectively, followed by application of a contrast sensitivity filter. The resulting images are combined according to mathematical prescriptions to produce a Just Noticeable Difference, JND value, indicative of a Spatial Standard Observer, SSO. Some embodiments include masking functions, window functions, special treatment for images lying on or near borders and pre-processing of test images.

  16. Application of spatially distributed coupled glacio-hydrological model to predict the effect of glacier recession on the flow of the Upper Bow River, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Naz, B. S.; Frans, C. D.; Clarke, G. K.; Nolin, A. W.; Lettenmaier, D. P.; Istanbulluoglu, E.; Burns, P. J.

    2011-12-01

    Several recent studies have suggested that observed decreases in summer flows in Canada's South Saskatchewan River are partly due to retreat of glaciers in the river's headwaters. Despite the risk posed by declining glaciers to water supply in the high mountain river systems, our ability to accurately predict runoff contribution from partially glacierized basins is limited. Modeling the effect of glacier changes on streamflow response in such basins is complicated due to limited availability of high resolution gridded meteorological data, lack of long term measurements of glaciological parameters and most importantly glacier dynamics are not linked to hydrological processes in many existing physically-based distributed hydrologic models. We investigate the effect of glacier recession on streamflow variations for the Upper Bow River basin, a tributary of the South Saskatchewan, near Lake Louise, Alberta, using the Distributed Hydrology Soil Vegetation Model (DHSVM) coupled with the spatially distributed glacier dynamics model. The coupled model is forced with the North American Regional Reanalysis (NARR) climate data for the period of 1979 - 2010 at a 3-hourly time step. The NARR data are adjusted for spatial variability in precipitation and temperature using the Parameter-elevation Regressions on Independent Slopes Model (PRISM) monthly data at 2.5 arcmin resolution made available through the Climate Western North America (ClimateWNA) database (Wang et al. 2006). Using known subglacial bed topography information, a multidecade spin-up run of the stand alone glacier model is first conducted until the beginning of the simulation period for the coupled model to accurately predict ice thickness confirmed through comparison of modeled ice margins with observed glacier extent. The integrated model initialized with already estimated glacier thickness and ice extent is then run to predict glacier evolution, including spatial extent in combination with other hydrologic

  17. Policy applications of a highly resolved spatial and temporal onroad carbon dioxide emissions data product for the U.S.: Analyses and their implications for mitigation

    NASA Astrophysics Data System (ADS)

    Mendoza Lebrun, Daniel

    Onroad CO2 emissions were analyzed as part of overall GHG emissions, but those studies have suffered from one or more of these five shortcomings: 1) the spatial resolution was coarse, usually encompassing a region, or the entire U.S.; 2) the temporal resolution was coarse (annual or monthly); 3) the study region was limited, usually a metropolitan planning organization (MPO) or state; 4) fuel sales were used as a proxy to quantify fuel consumption instead of focusing on travel; 5) the spatial heterogeneity of fleet and road network composition was not considered and instead national averages are used. Normalized vehicle-type state-level spatial biases range from 2.6% to 8.1%, while the road type classification biases range from -6.3% to 16.8%. These biases are found to cause errors in reduction estimates as large as ±60%, corresponding to ±0.2 MtC, for a national-average emissions mitigation strategy focused on a 10% emissions reduction from a single vehicle class. Temporal analysis shows distinct emissions seasonality that is particularly visible in the northernmost latitudes, demonstrating peak-to-peak deviations from the annual mean of up to 50%. The hourly structure shows peak-to-peak deviation from a weekly average of up to 200% for heavy-duty (HD) vehicles and 140% for light-duty (LD) vehicles. The present study focuses on reduction of travel and fuel economy improvements by putting forth several mitigation scenarios aimed at reducing VMT and increasing vehicle fuel efficiency. It was found that the most effective independent reduction strategies are those that increase fuel efficiency by extending standards proposed by the corporate average fuel economy (CAFE) or reduction of fuel consumption due to price increases. These two strategies show cumulative emissions reductions of approximately 11% and 12%, respectively, from a business as usual (BAU) approach over the 2000-2050 period. The U.S. onroad transportation sector is long overdue a comprehensive study

  18. Spatial information semantic query based on SPARQL

    NASA Astrophysics Data System (ADS)

    Xiao, Zhifeng; Huang, Lei; Zhai, Xiaofang

    2009-10-01

    How can the efficiency of spatial information inquiries be enhanced in today's fast-growing information age? We are rich in geospatial data but poor in up-to-date geospatial information and knowledge that are ready to be accessed by public users. This paper adopts an approach for querying spatial semantic by building an Web Ontology language(OWL) format ontology and introducing SPARQL Protocol and RDF Query Language(SPARQL) to search spatial semantic relations. It is important to establish spatial semantics that support for effective spatial reasoning for performing semantic query. Compared to earlier keyword-based and information retrieval techniques that rely on syntax, we use semantic approaches in our spatial queries system. Semantic approaches need to be developed by ontology, so we use OWL to describe spatial information extracted by the large-scale map of Wuhan. Spatial information expressed by ontology with formal semantics is available to machines for processing and to people for understanding. The approach is illustrated by introducing a case study for using SPARQL to query geo-spatial ontology instances of Wuhan. The paper shows that making use of SPARQL to search OWL ontology instances can ensure the result's accuracy and applicability. The result also indicates constructing a geo-spatial semantic query system has positive efforts on forming spatial query and retrieval.

  19. A high-spatial-resolution fiber-optic-coupled CMOS imager with novel scintillator for high-energy x-ray applications

    NASA Astrophysics Data System (ADS)

    Baur, Robin M.; Tate, Mark W.; Dale, Darren S.; Gruner, Sol M.

    2013-03-01

    A fast, high-spatial-resolution detector for high-energy microscopy work is presented. The detector uses a 2160 × 2560 CMOS chip for fast framing (up to 100 Hz in full-frame mode), coupled by a fiber optic taper to a scintillating Terbium-doped fiber optic plate for excellent stopping power even at high energies. The field of view is 7mm × 8.6mm with a resolution of 9 microns. The sensitivity is 1 e-/x-ray at 35 keV, with a read noise of 2.5 e-/pixel. Standard characterization metrics including dark current, sensitivity, modulation transfer function, and detective quantum efficiency are presented, along with preliminary experimental results.

  20. Differentiating Spatial Memory from Spatial Transformations

    ERIC Educational Resources Information Center

    Street, Whitney N.; Wang, Ranxiao Frances

    2014-01-01

    The perspective-taking task is one of the most common paradigms used to study the nature of spatial memory, and better performance for certain orientations is generally interpreted as evidence of spatial representations using these reference directions. However, performance advantages can also result from the relative ease in certain…

  1. Application of global positioning system methods for the study of obesity and hypertension risk among low-income housing residents in New York City: a spatial feasibility study.

    PubMed

    Duncan, Dustin T; Regan, Seann D; Shelley, Donna; Day, Kristen; Ruff, Ryan R; Al-Bayan, Maliyhah; Elbel, Brian

    2014-11-01

    The purpose of this study was to evaluate the feasibility of using global positioning system (GPS) methods to understand the spatial context of obesity and hypertension risk among a sample of low-income housing residents in New York City (n = 120). GPS feasibility among participants was measured with a pre- and post-survey as well as adherence to a protocol which included returning the GPS device as well as objective data analysed from the GPS devices. We also conducted qualitative interviews with 21 of the participants. Most of the sample was overweight (26.7%) or obese (40.0%). Almost one-third (30.8%) was pre-hypertensive and 39.2% was hypertensive. Participants reported high ratings of GPS acceptability, ease of use and low levels of wear-related concerns in addition to few concerns related to safety, loss or appearance, which were maintained after the baseline GPS feasibility data collection. Results show that GPS feasibility increased over time. The overall GPS return rate was 95.6%. Out of the total of 114 participants with GPS, 112 (98.2%) delivered at least one hour of GPS data for one day and 84 (73.7%) delivered at least one hour on 7 or more days. The qualitative interviews indicated that overall, participants enjoyed wearing the GPS devices, that they were easy to use and charge and that they generally forgot about the GPS device when wearing it daily. Findings demonstrate that GPS devices may be used in spatial epidemiology research in low-income and potentially other key vulnerable populations to understand geospatial determinants of obesity, hypertension and other diseases that these populations disproportionately experience. PMID:25545926

  2. Application of global positioning system methods for the study of obesity and hypertension risk among low-income housing residents in New York City: a spatial feasibility study

    PubMed Central

    Duncan, Dustin T.; Regan, Seann D.; Shelley, Donna; Day, Kristen; Ruff, Ryan R.; Al-Bayan, Maliyhah; Elbel, Brian

    2016-01-01

    The purpose of this study was to evaluate the feasibility of using global positioning system (GPS) methods to understand the spatial context of obesity and hypertension risk among a sample of low-income housing residents in New York City (n = 120). GPS feasibility among participants was measured with a pre- and post-survey as well as adherence to a protocol which included returning the GPS device as well as objective data analysed from the GPS devices. We also conducted qualitative interviews with 21 of the participants. Most of the sample was overweight (26.7%) or obese (40.0%). Almost one-third (30.8%) was pre-hypertensive and 39.2% was hypertensive. Participants reported high ratings of GPS acceptability, ease of use and low levels of wear-related concerns in addition to few concerns related to safety, loss or appearance, which were maintained after the baseline GPS feasibility data collection. Results show that GPS feasibility increased over time. The overall GPS return rate was 95.6%. Out of the total of 114 participants with GPS, 112 (98.2%) delivered at least one hour of GPS data for one day and 84 (73.7%) delivered at least one hour on 7 or more days. The qualitative interviews indicated that overall, participants enjoyed wearing the GPS devices, that they were easy to use and charge and that they generally forgot about the GPS device when wearing it daily. Findings demonstrate that GPS devices may be used in spatial epidemiology research in low-income and potentially other key vulnerable populations to understand geospatial determinants of obesity, hypertension and other diseases that these populations disproportionately experience. PMID:25545926

  3. From plane to spatial angles: PTB's spatial angle autocollimator calibrator

    NASA Astrophysics Data System (ADS)

    Kranz, Oliver; Geckeler, Ralf D.; Just, Andreas; Krause, Michael; Osten, Wolfgang

    2015-10-01

    Electronic autocollimators are utilised versatilely for non-contact angle measurements in applications like straightness measurements and profilometry. Yet, no calibration of the angle measurement of an autocollimator has been available when both its measurement axes are engaged. Additionally, autocollimators have been calibrated at fixed distances to the reflector, although its distance may vary during the use of an autocollimator. To extend the calibration capabilities of the Physikalisch-Technische Bundesanstalt (PTB) regarding spatial angles and variable distances, a novel calibration device has been set up: the spatial angle autocollimator calibrator (SAAC). In this paper, its concept and its mechanical realisation will be presented. The focus will be on the system's mathematical modelling and its application in spatial angle calibrations. The model considers the misalignments of the SAAC's components, including the non-orthogonalities of the measurement axes of the autocollimators and of the rotational axes of the tilting unit. It allows us to derive specific measurement procedures to determine the misalignments in situ and, in turn, to correct the measurements of the autocollimators. Finally, the realisation and the results of a traceable spatial angle calibration of an autocollimator will be presented. This is the first calibration of this type worldwide.

  4. Assessment of the water self-purification capacity on a river affected by organic pollution: application of chemometrics in spatial and temporal variations.

    PubMed

    González, S Oliva; Almeida, C A; Calderón, M; Mallea, M A; González, P

    2014-09-01

    Water pollution caused by organic matter is a major global problem which requires continuous evaluation. Multivariate statistical analysis was applied to assess spatial and temporal changes caused by natural and anthropogenic phenomena along Potrero de los Funes River. Cluster analysis (CA), principal component analysis (PCA) and analysis of variance (ANOVA) were applied to a data set collected throughout a period of 3 years (2010-2012), which monitored 22 physical, chemical and biological parameters. Content of dissolved oxygen in water and biochemical oxygen demand in a watercourse are indicators of pollution caused by organic matter. For this reason, the Streeter-Phelps model was used to evaluate the water self-purification capacity. Hierarchical cluster analysis grouped the sampling sites based on the similarity of water quality characteristics. PCA resulted in two latent factors explaining 75.2 and 17.6 % of the total variance in water quality data sets. Multidimensional ANOVA suggested that organic pollution is mainly due to domestic wastewater run-offs and anthropogenic influence as a consequence of increasing urbanization and tourist influx over the last years. Besides, Streeter-Phelps parameters showed a low reaeration capacity before dam with low concentration of dissolved oxygen. Furthermore, self-purification capacity loss was correlated with the decrease of the Benthic Index. This measurement suggested that biological samplings complement the physical-chemical analysis of water quality. PMID:24888622

  5. Quantitative assessment of a spatial multicriteria model for highly pathogenic avian influenza H5N1 in Thailand, and application in Cambodia

    PubMed Central

    Paul, Mathilde C.; Goutard, Flavie L.; Roulleau, Floriane; Holl, Davun; Thanapongtharm, Weerapong; Roger, François L.; Tran, Annelise

    2016-01-01

    The Highly Pathogenic Avian Influenza H5N1 (HPAI) virus is now considered endemic in several Asian countries. In Cambodia, the virus has been circulating in the poultry population since 2004, with a dramatic effect on farmers’ livelihoods and public health. In Thailand, surveillance and control are still important to prevent any new H5N1 incursion. Risk mapping can contribute effectively to disease surveillance and control systems, but is a very challenging task in the absence of reliable disease data. In this work, we used spatial multicriteria decision analysis (MCDA) to produce risk maps for HPAI H5N1 in poultry. We aimed to i) evaluate the performance of the MCDA approach to predict areas suitable for H5N1 based on a dataset from Thailand, comparing the predictive capacities of two sources of a priori knowledge (literature and experts), and ii) apply the best method to produce a risk map for H5N1 in poultry in Cambodia. Our results showed that the expert-based model had a very high predictive capacity in Thailand (AUC = 0.97). Applied in Cambodia, MCDA mapping made it possible to identify hotspots suitable for HPAI H5N1 in the Tonlé Sap watershed, around the cities of Battambang and Kampong Cham, and along the Vietnamese border. PMID:27489997

  6. Analysing urban resilience through alternative stormwater management options: application of the conceptual Spatial Decision Support System model at the neighbourhood scale.

    PubMed

    Balsells, M; Barroca, B; Amdal, J R; Diab, Y; Becue, V; Serre, D

    2013-01-01

    Recent changes in cities and their environments, caused by rapid urbanisation and climate change, have increased both flood probability and the severity of flooding. Consequently, there is a need for all cities to adapt to climate and socio-economic changes by developing new strategies for flood risk management. Following a risk paradigm shift from traditional to more integrated approaches, and considering the uncertainties of future urban development, one of the main emerging tasks for city managers becomes the development of resilient cities. However, the meaning of the resilience concept and its operability is still not clear. The goal of this research is to study how urban engineering and design disciplines can improve resilience to floods in urban neighbourhoods. This paper presents the conceptual Spatial Decision Support System (DS3) model which we consider a relevant tool to analyse and then implement resilience into neighbourhood design. Using this model, we analyse and discuss alternative stormwater management options at the neighbourhood scale in two specific areas: Rotterdam and New Orleans. The results obtained demonstrate that the DS3 model confirmed in its framework analysis that stormwater management systems can positively contribute to the improved flood resilience of a neighbourhood. PMID:24334895

  7. A software tool to model genetic regulatory networks. Applications to the modeling of threshold phenomena and of spatial patterning in Drosophila.

    PubMed

    Dilão, Rui; Muraro, Daniele

    2010-01-01

    We present a general methodology in order to build mathematical models of genetic regulatory networks. This approach is based on the mass action law and on the Jacob and Monod operon model. The mathematical models are built symbolically by the Mathematica software package GeneticNetworks. This package accepts as input the interaction graphs of the transcriptional activators and repressors of a biological process and, as output, gives the mathematical model in the form of a system of ordinary differential equations. All the relevant biological parameters are chosen automatically by the software. Within this framework, we show that concentration dependent threshold effects in biology emerge from the catalytic properties of genes and its associated conservation laws. We apply this methodology to the segment patterning in Drosophila early development and we calibrate the genetic transcriptional network responsible for the patterning of the gap gene proteins Hunchback and Knirps, along the antero-posterior axis of the Drosophila embryo. In this approach, the zygotically produced proteins Hunchback and Knirps do not diffuse along the antero-posterior axis of the embryo of Drosophila, developing a spatial pattern due to concentration dependent thresholds. This shows that patterning at the gap genes stage can be explained by the concentration gradients along the embryo of the transcriptional regulators. PMID:20523731

  8. Discussing State-of-the-Art Spatial Visualization Techniques Applicable for the Epidemiological Surveillance Data on the Example of Campylobacter spp. in Raw Chicken Meat.

    PubMed

    Plaza-Rodríguez, C; Appel, B; Kaesbohrer, A; Filter, M

    2016-08-01

    Within the European activities for the 'Monitoring and Collection of Information on Zoonoses', annually EFSA publishes a European report, including information related to the prevalence of Campylobacter spp. in Germany. Spatial epidemiology becomes here a fundamental tool for the generation of these reports, including the representation of prevalence as an essential element. Until now, choropleth maps are the default visualization technique applied in epidemiological monitoring and surveillance reports made by EFSA and German authorities. However, due to its limitations, it seems to be reasonable to explore alternative chart type. Four maps including choropleth, cartogram, graduated symbols and dot-density maps were created to visualize real-world sample data on the prevalence of Campylobacter spp. in raw chicken meat samples in Germany in 2011. In addition, adjacent and coincident maps were created to visualize also the associated uncertainty. As an outcome, we found that there is not a single data visualization technique that encompasses all the necessary features to visualize prevalence data alone or prevalence data together with their associated uncertainty. All the visualization techniques contemplated in this study demonstrated to have both advantages and disadvantages. To determine which visualization technique should be used for future reports, we recommend to create a dialogue between end-users and epidemiologists on the basis of sample data and charts. The final decision should also consider the knowledge and experience of end-users as well as the specific objective to be achieved with the charts. PMID:26404056

  9. Quantitative assessment of a spatial multicriteria model for highly pathogenic avian influenza H5N1 in Thailand, and application in Cambodia.

    PubMed

    Paul, Mathilde C; Goutard, Flavie L; Roulleau, Floriane; Holl, Davun; Thanapongtharm, Weerapong; Roger, François L; Tran, Annelise

    2016-01-01

    The Highly Pathogenic Avian Influenza H5N1 (HPAI) virus is now considered endemic in several Asian countries. In Cambodia, the virus has been circulating in the poultry population since 2004, with a dramatic effect on farmers' livelihoods and public health. In Thailand, surveillance and control are still important to prevent any new H5N1 incursion. Risk mapping can contribute effectively to disease surveillance and control systems, but is a very challenging task in the absence of reliable disease data. In this work, we used spatial multicriteria decision analysis (MCDA) to produce risk maps for HPAI H5N1 in poultry. We aimed to i) evaluate the performance of the MCDA approach to predict areas suitable for H5N1 based on a dataset from Thailand, comparing the predictive capacities of two sources of a priori knowledge (literature and experts), and ii) apply the best method to produce a risk map for H5N1 in poultry in Cambodia. Our results showed that the expert-based model had a very high predictive capacity in Thailand (AUC = 0.97). Applied in Cambodia, MCDA mapping made it possible to identify hotspots suitable for HPAI H5N1 in the Tonlé Sap watershed, around the cities of Battambang and Kampong Cham, and along the Vietnamese border. PMID:27489997

  10. An application of remotely derived climatological fields for risk assessment of vector-borne diseases : a spatial study of filariasis prevalence in the Nile Delta, Egypt.

    SciTech Connect

    Crombie, M. K.; Gillies, R. R.; Arvidson, R. E.; Brookmeyer, P.; Weil, G. J.; Sultan, M.; Harb, M.; Environmental Research; Washington Univ.; Utah State Univ.; Egyptian Ministry of Health

    1999-12-01

    This paper applies a relatively straightforward remote sensing method that is commonly used to derive climatological variables. Measurements of surface reflectance and surface radiant temperature derived from Landsat Thematic Mapper data were used to create maps of fractional vegetation and surface soil moisture availability for the southern Nile delta in Egypt. These climatological variables were subsequently used to investigate the spatial distribution of the vector borne disease Bancroftian filariasis in the Nile delta where it is focally endemic and a growing problem. Averaged surface soil moisture values, computed for a 5-km border area around affected villages, were compared to filariasis prevalence rates. Prevalence rates were found to be negligible below a critical soil moisture value of 0.2, presumably because of a lack of appropriate breeding sites for the Culex Pipiens mosquito species. With appropriate modifications to account for local conditions and vector species, this approach should be useful as a means to map, predict, and control insect vector-borne diseases that critically depend on wet areas for propagation. This type of analysis may help governments and health agencies that are involved in filariasis control to better focus limited resources to identifiable high-risk areas.

  11. Measurements of the temporal and spatial phase variations of a 33 GHz pulsed free electron laser amplifier and application to high gradient RF acceleration

    SciTech Connect

    Volfbeyn, P.; Bekefi, G.

    1995-12-31

    We report the results of temporal and spatial measurements of phase of a pulsed free electron laser amplifier (FEL) operating in combined wiggler and axial guide magnetic fields. The 33 GHz FEL is driven by a mildly relativistic electron beam (750 kV, 90-300 A, 30 ns) and generates 61 MW of radiation with a high power magnetron as the input source. The phase is measured by an interferometric technique from which frequency shifting is determined. The results are simulated with a computer code. Experimental studies on a CERN-CLIC 32.98 GHz 26-cell high gradient accelerating section (HGA) were carried out for input powers from 0.1 MW to 35 MW. The FEL served as the r.f. power source for the HGA. The maximum power in the transmitted pulse was measured to be 15 MW for an input pulse of 35 MW. The theoretically calculated shunt impedance of 116 M{Omega}/m predicts a field gradient of 65 MeV/m inside the HGA. For power levels >3MW the pulse transmitted through the HGA was observed to be shorter than the input pulse and pulse shortening became more serious with increasing power input. At the highest power levels the output pulse length (about 5 nsec) was about one quarter of the input pulse length. Various tests suggest that these undesirable effects occur in the input coupler to the HGA. Light and X-ray production inside the HGA have been observed.

  12. Nitroreductase-mediated cell/tissue ablation in zebrafish: a spatially and temporally controlled ablation method with applications in developmental and regeneration studies

    PubMed Central

    Curado, Silvia; Stainier, Didier Y R; Anderson, Ryan M

    2009-01-01

    Ablation studies are used to elucidate cell lineage relationships, developmental roles for specific cells during embryogenesis and mechanisms of tissue regeneration. Previous chemical and genetic approaches to directed cell ablation have been hampered by poor specificity, limited efficacy, irreversibility, hypersensitivity to promoter leakiness, restriction to proliferating cells, slow inducibility or complex genetics. Here, we provide a step-by-step protocol for a hybrid chemical-genetic cell ablation method in zebrafish that, by combining spatial and temporal control, is cell-type specific, inducible, reversible, rapid and scaleable. Bacterial Nitroreductase (NTR) is used to catalyze the reduction of the innocuous prodrug metrodinazole (Mtz), thereby producing a cytotoxic product that induces cell death. Based on this principle, NTR is expressed in transgenic zebrafish using a tissue-specific promoter. Subsequent exposure to Mtz by adding it to the media induces cell death exclusively within NTR+ cells. This approach can be applied to regeneration studies, as removing Mtz by washing permits tissue recovery. Using this protocol, cell ablation can be achieved in 12–72 h, depending on the transgenic line used, and recovery initiates within the following 24 h. PMID:18536643

  13. A spatially explicit model of runoff, evaporation, and lake extent: Application to modern and late Pleistocene lakes in the Great Basin region, western United States

    NASA Astrophysics Data System (ADS)

    Matsubara, Yo; Howard, Alan D.

    2009-06-01

    A spatially explicit hydrological model was applied to the Great Basin in the western United States to predict runoff magnitude and lake distributions under modern and late Pleistocene conditions. The model iteratively routes runoff through depression to find a steady state solution and was calibrated with mean annual precipitation, pan evaporation, temperature, and stream runoff data. The predicted lake distribution provides a close match to present-day lakes. For the late Pleistocene, the sizes of lakes Bonneville and Lahontan are well predicted by linear combinations of 0.2°-5.8°C decreases in temperature and corresponding increases in precipitation from 2.0 to 1.0 times modern values. This corresponds to runoff depths ranging from 1.7 to 4.1 times the present values and yearly evaporation from 0.4 to 1 times modern values. To reproduce Lake Manly, however, combinations of temperature decreases up to 9°C or precipitation up to 2.8 times the present values were required.

  14. Part II: temporal and spatial distribution of multiclass pesticide residues in lake sediments of northern Greece: application of an optimized MAE-LC-MS/MS pretreatment and analytical method.

    PubMed

    Kalogridi, Eleni-Chrysoula; Christophoridis, Christophoros; Bizani, Erasmia; Drimaropoulou, Garyfallia; Fytianos, Konstantinos

    2014-06-01

    The development and application of an analytical methodology for the pretreatment and determination of 253 multiclass pesticides, in lake sediment samples, using liquid chromatography coupled with mass spectrometry (LC-MS/MS) are described in this work. Sediments of lakes Volvi, Doirani, and Kerkini, located in northern Greece, were collected in two-time periods (fall/winter 2010 and spring/summer 2011) and analyzed, applying the developed analytical methodology. Microwave-assisted extraction (MAE) was applied to extract the pesticide residues from lake sediment samples. Analytical results were stored, categorized, and visualized using geographical information systems, in order to assess and observe spatial and temporal variations of the pollution. Main pesticides that were detected included the following: amitrole, tebuconazole, phoxim, diniconazole, sethoxydim, temephos, tetrachlorvinphos, pendimethalin, boscalid, disulfoton sulfone, lenacil, propiconazole, cycloxydim, pyridaben, and terbuthylazine. Amitrole, diniconazole, and tebuconazole were found to be common in all three lakes. Lakes Kerkini and Doirani exhibited increased concentrations during the first sampling period (winter 2010) with predominant pesticide classes, triazines/triazoles and organophosphates. Pollution is mainly located near the populated villages of the lakes and the nearby cultivations. During the second sampling period, pesticide concentrations appear lower and located in sediments near the center of the lake. Lake Volvi exhibits increased pesticide concentrations during the second sampling period, temporal and spatial variations and different pesticide profile pattern. Increased pollution occurs near the center of the lake during the first sampling period, mainly comprised by triazines/triazoles and organophosphates. During the second sampling period, the majority of the sediment samples demonstrated a different pesticide profile dominated by unclassified pesticides and triazines

  15. Spatial and temporal heterogeneity explain disease dynamics in a spatially explicit network model.

    PubMed

    Brooks, Christopher P; Antonovics, Janis; Keitt, Timothy H

    2008-08-01

    There is an increasing recognition that individual-level spatial and temporal heterogeneity may play an important role in metapopulation dynamics and persistence. In particular, the patterns of contact within and between aggregates (e.g., demes) at different spatial and temporal scales may reveal important mechanisms governing metapopulation dynamics. Using 7 years of data on the interaction between the anther smut fungus (Microbotryum violaceum) and fire pink (Silene virginica), we show how the application of spatially explicit and implicit network models can be used to make accurate predictions of infection dynamics in spatially structured populations. Explicit consideration of both spatial and temporal organization reveals the role of each in spreading risk for both the host and the pathogen. This work suggests that the application of spatially explicit network models can yield important insights into how heterogeneous structure can promote the persistence of species in natural landscapes. PMID:18662121

  16. Effects of spatial resolution

    NASA Technical Reports Server (NTRS)

    Abrams, M.

    1982-01-01

    Studies of the effects of spatial resolution on extraction of geologic information are woefully lacking but spatial resolution effects can be examined as they influence two general categories: detection of spatial features per se; and the effects of IFOV on the definition of spectral signatures and on general mapping abilities.

  17. Spatial Language Learning

    ERIC Educational Resources Information Center

    Fu, Zhengling

    2016-01-01

    Spatial language constitutes part of the basic fabric of language. Although languages may have the same number of terms to cover a set of spatial relations, they do not always do so in the same way. Spatial languages differ across languages quite radically, thus providing a real semantic challenge for second language learners. The essay first…

  18. Spatial Solitons in Algaas Waveguides

    NASA Astrophysics Data System (ADS)

    Kang, Jin Ung

    In this work, by measuring the two-, three-photon absorption, and the nonlinear refractive index coefficients, a useful bandwidth for an all-optical switching applications in the AlGaAs below half the band gap is identified. Operating in this material system, several types of spatial solitons such as fundamental bright solitons, Vector solitons, and Manakov solitons are experimentally demonstrated. The propagation and the interaction behaviors of these solitons are studied experimentally and numerically. The distinct properties of each soliton are discussed along with some possible applications. Some applications, such as all -optical switching based on spatial soliton dragging and the efficient guiding of orthogonally polarized femtosecond pulses by a bright spatial soliton, are experimentally demonstrated. The signal gain due to an ultrafast polarization coupling, better known as Four Wave Mixing (FWM) is demonstrated in a channel waveguide. The effects of FWM are studied experimentally and numerically. This effect is also used to demonstrate polarization switching. The linear and nonlinear properties of AlGaAs/GaAs multiple quantum well waveguides are measured. Anisotropic two photon absorption and nonlinear refractive indices near half the band gap are measured along with the linear birefringence for several different quantum well structures. The usefulness of multiple quantum well structures for an all -optical switching because of anisotropic nature of this material system is discussed.

  19. Application of Spatial and Closed Capture-Recapture Models on Known Population of the Western Derby Eland (Taurotragus derbianus derbianus) in Senegal

    PubMed Central

    Jůnek, Tomáš; Jůnková Vymyslická, Pavla; Hozdecká, Kateřina; Hejcmanová, Pavla

    2015-01-01

    Camera trapping with capture-recapture analyses has provided estimates of the abundances of elusive species over the last two decades. Closed capture-recapture models (CR) based on the recognition of individuals and incorporating natural heterogeneity in capture probabilities are considered robust tools; however, closure assumption is often questionable and the use of an Mh jackknife estimator may fail in estimations of real abundance when the heterogeneity is high and data is sparse. A novel, spatially explicit capture-recapture (SECR) approach based on the location-specific capture histories of individuals overcomes the limitations of closed models. We applied both methods on a closed population of 16 critically endangered Western Derby elands in the fenced 1,060-ha Fathala reserve, Senegal. We analyzed the data from 30 cameras operating during a 66-day sampling period deployed in two densities in grid and line arrays. We captured and identified all 16 individuals in 962 trap-days. Abundances were estimated in the programs CAPTURE (models M0, Mh and Mh Chao) and R, package secr (basic Null and Finite mixture models), and compared with the true population size. We specified 66 days as a threshold in which SECR provides an accurate estimate in all trapping designs within the 7-times divergent density from 0.004 to 0.028 camera trap/ha. Both SECR models showed uniform tendency to overestimate abundance when sampling lasted shorter with no major differences between their outputs. Unlike the closed models, SECR performed well in the line patterns, which indicates promising potential for linear sampling of properly defined habitats of non-territorial and identifiable herbivores in dense wooded savanna conditions. The CR models provided reliable estimates in the grid and we confirmed the advantage of Mh Chao estimator over Mh jackknife when data appeared sparse. We also demonstrated the pooling of trapping occasions with an increase in the capture probabilities

  20. Development and application of methods to quantify spatial and temporal hyperpolarized 3He MRI ventilation dynamics: preliminary results in chronic obstructive pulmonary disease

    NASA Astrophysics Data System (ADS)

    Kirby, Miranda; Wheatley, Andrew; McCormack, David G.; Parraga, Grace

    2010-03-01

    Hyperpolarized helium-3 (3He) magnetic resonance imaging (MRI) has emerged as a non-invasive research method for quantifying lung structural and functional changes, enabling direct visualization in vivo at high spatial and temporal resolution. Here we described the development of methods for quantifying ventilation dynamics in response to salbutamol in Chronic Obstructive Pulmonary Disease (COPD). Whole body 3.0 Tesla Excite 12.0 MRI system was used to obtain multi-slice coronal images acquired immediately after subjects inhaled hyperpolarized 3He gas. Ventilated volume (VV), ventilation defect volume (VDV) and thoracic cavity volume (TCV) were recorded following segmentation of 3He and 1H images respectively, and used to calculate percent ventilated volume (PVV) and ventilation defect percent (VDP). Manual segmentation and Otsu thresholding were significantly correlated for VV (r=.82, p=.001), VDV (r=.87 p=.0002), PVV (r=.85, p=.0005), and VDP (r=.85, p=.0005). The level of agreement between these segmentation methods was also evaluated using Bland-Altman analysis and this showed that manual segmentation was consistently higher for VV (Mean=.22 L, SD=.05) and consistently lower for VDV (Mean=-.13, SD=.05) measurements than Otsu thresholding. To automate the quantification of newly ventilated pixels (NVp) post-bronchodilator, we used translation, rotation, and scaling transformations to register pre-and post-salbutamol images. There was a significant correlation between NVp and VDV (r=-.94 p=.005) and between percent newly ventilated pixels (PNVp) and VDP (r=- .89, p=.02), but not for VV or PVV. Evaluation of 3He MRI ventilation dynamics using Otsu thresholding and landmark-based image registration provides a way to regionally quantify functional changes in COPD subjects after treatment with beta-agonist bronchodilators, a common COPD and asthma therapy.

  1. Application of a spatially distributed water balance model for assessing surface water and groundwater resources in the Geba basin, Tigray, Ethiopia

    NASA Astrophysics Data System (ADS)

    Gebreyohannes, Tesfamichael; De Smedt, Florimond; Walraevens, Kristine; Gebresilassie, Solomon; Hussien, Abdelwasie; Hagos, Miruts; Amare, Kasa; Deckers, Jozef; Gebrehiwot, Kindeya

    2013-08-01

    The Geba basin is one of the most water-stressed areas of Ethiopia, with only a short rainy period from mid-June to mid-September. Because rainfall in this region has been consistently erratic in the last decades, both in time and space, rain-fed agriculture has become problematic. Hence, in order to supplement rain-fed agriculture by irrigation, a detailed understanding of local and regional surface water and groundwater resources is important. The main objective of this study is to assess the available water resources in the Geba basin using a spatially distributed water balance model (WetSpass). Relevant input data for the model is prepared in the form of digital maps using remote sensing images, GIS tools, FAO and NASA databases, field reconnaissance and processing of meteorological and hydrological observations. The model produces digital maps of long-term average, seasonal and annual surface runoff, evapotranspiration and groundwater recharge. Results of the model show that 76% of the precipitation in the basin is lost through evapotranspiration, 18% becomes surface runoff and only 6% recharges the groundwater system. Model predictions are verified against river flow observations and are shown to be reliable. Additional maps are derived of accumulated surface runoff, safe yield for groundwater abstraction and water deficit for crop growth. Comparison of existing reservoirs with the accumulated runoff map shows that many reservoirs have failed because their design capacity is much higher than the actual inflow. Comparison of the safe yield map with the crop water deficit map shows that in most areas groundwater can be safely abstracted to supplement the water deficit for crop growth during the wet summer season. However, in the dry winter season the crop water deficit is too high to be supplemented by groundwater abstraction in a sustainable way.

  2. Temporal and spatial variability of tidal-fluvial dynamics in the St. Lawrence fluvial estuary: An application of nonstationary tidal harmonic analysis

    NASA Astrophysics Data System (ADS)

    Matte, Pascal; Secretan, Yves; Morin, Jean

    2014-09-01

    Predicting tides in upstream reaches of rivers is a challenge, because tides are highly nonlinear and nonstationary, and accurate short-time predictions of river flow are hard to obtain. In the St. Lawrence fluvial estuary, tide forecasts are produced using a one-dimensional model (ONE-D), forced downstream with harmonic constituents, and upstream with daily discharges using 30 day flow forecasts from Lake Ontario and the Ottawa River. Although this operational forecast system serves its purpose of predicting water levels, information about nonstationary tidal-fluvial processes that can be gained from it is limited, particularly the temporal changes in mean water level and tidal properties (i.e., constituent amplitudes and phases), which are function of river flow and ocean tidal range. In this paper, a harmonic model adapted to nonstationary tides, NS_TIDE, was applied to the St. Lawrence fluvial estuary, where the time-varying external forcing is directly built into the tidal basis functions. Model coefficients from 13 analysis stations were spatially interpolated to allow tide predictions at arbitrary locations as well as to provide insights into the spatiotemporal evolution of tides. Model hindcasts showed substantial improvements compared to classical harmonic analyses at upstream stations. The model was further validated by comparison with ONE-D predictions at a total of 32 stations. The slightly lower accuracy obtained with NS_TIDE is compensated by model simplicity, efficiency, and capacity to represent stage and tidal variations in a very compact way and thus represents a new means for understanding tidal rivers.

  3. Application of Spatial and Closed Capture-Recapture Models on Known Population of the Western Derby Eland (Taurotragus derbianus derbianus) in Senegal.

    PubMed

    Jůnek, Tomáš; Jůnková Vymyslická, Pavla; Hozdecká, Kateřina; Hejcmanová, Pavla

    2015-01-01

    Camera trapping with capture-recapture analyses has provided estimates of the abundances of elusive species over the last two decades. Closed capture-recapture models (CR) based on the recognition of individuals and incorporating natural heterogeneity in capture probabilities are considered robust tools; however, closure assumption is often questionable and the use of an Mh jackknife estimator may fail in estimations of real abundance when the heterogeneity is high and data is sparse. A novel, spatially explicit capture-recapture (SECR) approach based on the location-specific capture histories of individuals overcomes the limitations of closed models. We applied both methods on a closed population of 16 critically endangered Western Derby elands in the fenced 1,060-ha Fathala reserve, Senegal. We analyzed the data from 30 cameras operating during a 66-day sampling period deployed in two densities in grid and line arrays. We captured and identified all 16 individuals in 962 trap-days. Abundances were estimated in the programs CAPTURE (models M0, Mh and Mh Chao) and R, package secr (basic Null and Finite mixture models), and compared with the true population size. We specified 66 days as a threshold in which SECR provides an accurate estimate in all trapping designs within the 7-times divergent density from 0.004 to 0.028 camera trap/ha. Both SECR models showed uniform tendency to overestimate abundance when sampling lasted shorter with no major differences between their outputs. Unlike the closed models, SECR performed well in the line patterns, which indicates promising potential for linear sampling of properly defined habitats of non-territorial and identifiable herbivores in dense wooded savanna conditions. The CR models provided reliable estimates in the grid and we confirmed the advantage of Mh Chao estimator over Mh jackknife when data appeared sparse. We also demonstrated the pooling of trapping occasions with an increase in the capture probabilities

  4. Spatially-Heterodyned Holography

    SciTech Connect

    Thomas, Clarence E; Hanson, Gregory R

    2006-02-21

    A method of recording a spatially low-frequency heterodyne hologram, including spatially heterodyne fringes for Fourier analysis, includes: splitting a laser beam into a reference beam and an object beam; interacting the object beam with an object; focusing the reference beam and the object beam at a focal plane of a digital recorder to form a spatially low-frequency heterodyne hologram including spatially heterodyne fringes for Fourier analysis; digital recording the spatially low-frequency heterodyne hologram; Fourier transforming axes of the recorded spatially low-frequency heterodyne hologram including spatially heterodyne fringes in Fourier space to sit on top of a heterodyne carrier frequency defined by an angle between the reference beam and the object beam; cutting off signals around an origin; and performing an inverse Fourier transform.

  5. Spatial profiling using a Time of Flight Diagnostic and applications of deuterim-deuterium fusion in Inertial Electrostatic Confinement fusion devices

    NASA Astrophysics Data System (ADS)

    Donovan, David C.

    2011-12-01

    The Inertial Electrostatic Confinement (IEC) Fusion Research Group at the University of Wisconsin-Madison utilizes IEC devices as small-scale neutron generators using D-D fusion to create 2.45 MeV neutrons for the purpose of detecting clandestine material. Detection of explosives in particular can be accomplished using thermal neutron capture methods to identify characteristic nitrogen signatures in explosive material. Research has been conducted to increase reliability of detection, decrease interrogation time, and increase the steady-state operational time. Efforts have also been made to increase the neutron production rate of the device. Optimization studies have varied the configuration and design of the electrodes and have resulted in system configurations with up to 50 percent higher neutron production rates than have previously been utilized. A new feedthrough design has been constructed that is intended to increase the maximum operating voltage from 175 kV with the previous feedthrough to 300 kV. Neutron production rates scale almost linearly with both current and voltage, so the IEC device will be capable of operation at higher neutron producing regimes than have ever before been achieved. The optimization efforts involve the use of several new diagnostic tools developed at UW, which are the Fusion Ion Doppler (FIDO) Diagnostic and the Time of Flight (TOF) Diagnostic. FIDO provides the energy spectra of the charged fusion products and reactants created in the IEC device. The FIDO Diagnostic was originally only capable of studying D-D fusion, but with recent advancements is now able to study both D-D and D-3He fusion. The TOF Diagnostic provides spatial information along with the energy resolution of where the fusion reactions are occurring in the IEC device. Development of the diagnostics has involved the implementation of timing electronics, alignment systems, data acquisition software, computational post-processing, and upgrades to the experimental

  6. Application of a two-dimensional model to describe the CO2 exchange between a spatially non-uniform forest stand and the atmosphere

    NASA Astrophysics Data System (ADS)

    Mukhartova, Yulia; Olchev, Alexander; Shapkina, Natalia

    2014-05-01

    Within the framework of the study a two dimensional hydrodynamic high-resolution model of the energy, H2O, CO2 turbulent exchange was developed and applied to describe effect of the horizontal and vertical heterogeneity of a forest canopy on CO2exchange between soil surface, forest stand and the atmosphere under different weather conditions. Most attention in the study was paid to analyze the influence of forest clearing, windthrow of different sizes, forest edges, etc. on turbulent exchange rate and CO2 flux partitioning between forest overstorey, understorey and soil surface. The modeling experiments were provided under different wind conditions, thermal stratification of the atmospheric boundary layer, incoming solar radiation, etc. To quantify effect of spatial heterogeneity on total ecosystem fluxes the modeling results were compared with CO2 fluxes modeled for a spatially uniform forest canopy under similar ambient conditions. The averaged system of hydrodynamic equations is used for calculating the components of the mean velocity →V = {V1, V2}: ( ( ) ) δVi+ V δVi= - 1-δδP- - -δ- δ E - K δVi-+ δVj- + F, δVi = 0, δt jδxj ρ0 δxi δxj ij δxj δxi i δxi where E is the turbulent kinetic energy (TKE), K is the turbulent diffusivity, δP is the deviation of pressure from the hydrostatic distribution and ρ0→F is the averaged force of air flow interaction with vegetation. F→ was parameterized as →F = -cd ·LAD ·| | ||V→||·→V, where cd is the drag coefficient and LAD is the leaf area density. The turbulent diffusivity K can be expressed by means of TKE and the velocity of TKE dissipation ɛ as follows: K = CμE2ɛ-1, where Cμ is the proportionality coefficient. One of the ways to obtain E and ɛ is to solve the additional system of two differential equations of diffusion-transport type: ( ) ( ) δE- -δE- -δ- -K-δE- δ-ϕ δϕ- -δ- K-δϕ -ϕ ( 1 2 ) δt +Vjδxj = δxi σE δxi +PE - ɛ, δt +Vj δxj = δxi σϕδxi +E C ϕPE - C

  7. Development of online Spatial Multi-Criteria Decision Analyst application: Case study on determining area suitability for school location in Surabaya, Indonesia

    NASA Astrophysics Data System (ADS)

    HaryPrasetyo, Daniel; Muhamad, Jamilah; Fauzi, Rosmadi

    2016-06-01

    A decision sometimes needs to consider many aspects and to be judged by many people. Presenting a case of finding a suitable location for a new school this research proposes seven factors which its emphasis will be differently sorted by various people perspective. Each factor comes in a form of a multi-polygon layer that valued from 0 to 9, representing the suitability value of the certain aspect in the whole city area. The Public and some expert will judge by using the pair-wise comparison of those aspects. This research will provide web GIS application that will use by the public and the expert in this justification process and analyzing the result.

  8. Rethinking the linear regression model for spatial ecological data.

    PubMed

    Wagner, Helene H

    2013-11-01

    The linear regression model, with its numerous extensions including multivariate ordination, is fundamental to quantitative research in many disciplines. However, spatial or temporal structure in the data may invalidate the regression assumption of independent residuals. Spatial structure at any spatial scale can be modeled flexibly based on a set of uncorrelated component patterns (e.g., Moran's eigenvector maps, MEM) that is derived from the spatial relationships between sampling locations as defined in a spatial weight matrix. Spatial filtering thus addresses spatial autocorrelation in the residuals by adding such component patterns (spatial eigenvectors) as predictors to the regression model. However, space is not an ecologically meaningful predictor, and commonly used tests for selecting significant component patterns do not take into account the specific nature of these variables. This paper proposes "spatial component regression" (SCR) as a new way of integrating the linear regression model with Moran's eigenvector maps. In its unconditioned form, SCR decomposes the relationship between response and predictors by component patterns, whereas conditioned SCR provides an alternative method of spatial filtering, taking into account the statistical properties of component patterns in the design of statistical hypothesis tests. Application to the well-known multivariate mite data set illustrates how SCR may be used to condition for significant residual spatial structure and to identify additional predictors associated with residual spatial structure. Finally, I argue that all variance is spatially structured, hence spatial independence is best characterized by a lack of excess variance at any spatial scale, i.e., spatial white noise. PMID:24400490

  9. Application of thermal analysis to measure the spatial heterogeneity of organic matter degradation after wildfire: implications for post-fire rehabilitation treatments

    NASA Astrophysics Data System (ADS)

    Merino, Agustin; Fonturbel, M. Teresa; Vega, Jose A.

    2015-04-01

    Severe wildfires can cause drastic changes in SOM content and quality with important implications for soil conservation and global C balance. Soil heating usually leads to loss of the most labile SOM compounds (e.g. carbohydrates, lipids and peptides) and to generation of aromatic substances. However, these fire-related damages are not uniform over large areas, because of the spatial heterogeneity of different factors such as fire type and environmental conditions. Rapid diagnosis of soil burn severity is required to enable the design of emergency post-fire rehabilitation treatments. The study was conducted in soils from NW Spain, an Atlantic-climate zone that is particularly prone to wildfires. Intact soil cores (forest floor and uppermost mineral soil layer) were taken from a soil developed under granitic rock and subjected to experimental burning (in a bench positioned at the outlet of a wind tunnel). Soil temperature during fire was monitorised and five visual levels of soil burn severity (SBS) were recorded immediately after fire. Solid-state 13C CP-MAS NMR spectroscopy analyses were performed in an Agilent (Varian) VNMRS-500-WB spectrometer. The samples were analyzed by differential scanning calorimetry and thermogravimetry (TGA/DSC, Mettler-Toledo Intl. Inc.). The analyses were performed with 4 mg of samples placed in open aluminium pans under dry air (flow rate, 50 mL-1) and at a scanning rate of 10 °C min-1. The temperature ranged between 50 and 600 °C. In the organic layer, the temperature reached during fire influenced the formation and characteristics of charred material. These materials showed an increasing degree of carbonization/aromatization in relation to the increase of temperature during burning. Burning also led to compounds of higher thermal recalcitrance (increases in T50 values -the temperature at which 50% of the energy stored in SOM is released-). However, values recorded in some samples were lower than those measured in highly

  10. Application of Spatial Data Modeling and Geographical Information Systems (GIS) for Identification of Potential Siting Options for Various Electrical Generation Sources

    SciTech Connect

    Mays, Gary T; Belles, Randy; Blevins, Brandon R; Hadley, Stanton W; Harrison, Thomas J; Jochem, Warren C; Neish, Bradley S; Omitaomu, Olufemi A; Rose, Amy N

    2012-05-01

    Oak Ridge National Laboratory (ORNL) initiated an internal National Electric Generation Siting Study, which is an ongoing multiphase study addressing several key questions related to our national electrical energy supply. This effort has led to the development of a tool, OR-SAGE (Oak Ridge Siting Analysis for power Generation Expansion), to support siting evaluations. The objective in developing OR-SAGE was to use industry-accepted approaches and/or develop appropriate criteria for screening sites and employ an array of Geographic Information Systems (GIS) data sources at ORNL to identify candidate areas for a power generation technology application. The initial phase of the study examined nuclear power generation. These early nuclear phase results were shared with staff from the Electric Power Research Institute (EPRI), which formed the genesis and support for an expansion of the work to several other power generation forms, including advanced coal with carbon capture and storage (CCS), solar, and compressed air energy storage (CAES). Wind generation was not included in this scope of work for EPRI. The OR-SAGE tool is essentially a dynamic visualization database. The results shown in this report represent a single static set of results using a specific set of input parameters. In this case, the GIS input parameters were optimized to support an economic study conducted by EPRI. A single set of individual results should not be construed as an ultimate energy solution, since US energy policy is very complex. However, the strength of the OR-SAGE tool is that numerous alternative scenarios can be quickly generated to provide additional insight into electrical generation or other GIS-based applications. The screening process divides the contiguous United States into 100 x 100 m (1-hectare) squares (cells), applying successive power generation-appropriate site selection and evaluation criteria (SSEC) to each cell. There are just under 700 million cells representing the

  11. Development of EMC-based empirical model for estimating spatial distribution of pollutant loads and its application in rural areas of Korea.

    PubMed

    Yi, Qitao; Li, Hui; Lee, Jin-Woo; Kim, Youngchul

    2015-09-01

    An integrated approach to easily calculate pollutant loads from agricultural watersheds is suggested and verified in this research. The basic concepts of this empirical tool were based on the assumption that variations in event mean concentrations (EMCs) of pollutants from a given agricultural watershed during rainstorms were only attributable to the rainfall pattern. Fifty one sets of EMC values were obtained from nine different watersheds located in the rural areas of Korea, and these data were used to develop predictive tools for the EMCs in rainfall runoff. The results of statistical tests of these formulas show that they are fairly good in predicting actual EMC values of some parameters, and useful in terms of calculating pollutant loads for any rainfall event time span such as daily, weekly, monthly, and yearly. This model was further checked in for its field applicability in a reservoir receiving stormwater after a cleanup of the sediments, covering 17 consecutive rainfall events from 1 July to 15 August in 2007. Overall the predicted values matched the observed values, indicating the feasibility of this empirical tool as a simple and useful solution in evaluating timely distribution of nonpoint source pollution loads from small rural watersheds of Korea. PMID:26354686

  12. Risk assessment of down-the-drain chemicals at large spatial scales: Model development and application to contaminants originating from urban areas in the Saint Lawrence River Basin.

    PubMed

    Grill, Günther; Khan, Usman; Lehner, Bernhard; Nicell, Jim; Ariwi, Joseph

    2016-01-15

    Chemicals released into freshwater systems threaten ecological functioning and may put aquatic life and the health of humans at risk. We developed a new contaminant fate model (CFM) that follows simple, well-established methodologies and is unique in its cross-border, seamless hydrological and geospatial framework, including lake routing, a critical component in northern environments. We validated the model using the pharmaceutical Carbamazepine and predicted eco-toxicological risk for 15 pharmaceuticals in the Saint-Lawrence River Basin, Canada. The results indicated negligible to low environmental risk for the majority of tested chemicals, while two pharmaceuticals showed elevated risk in up to 13% of rivers affected by municipal effluents. As an integrated model, our CFM is designed for application at very large scales with the primary goal of detecting high risk zones. In regulatory frameworks, it can help screen existing or new chemicals entering the market regarding their potential impact on human and environmental health. Due to its high geospatial resolution, our CFM can also facilitate the prioritization of actions, such as identifying regions where reducing contamination sources or upgrading treatment plants is most pertinent to achieve targeted pollutant removal or to protect drinking water resources. PMID:26437353

  13. Detecting of transient vibration signatures using an improved fast spatial-spectral ensemble kurtosis kurtogram and its applications to mechanical signature analysis of short duration data from rotating machinery

    NASA Astrophysics Data System (ADS)

    Chen, BinQiang; Zhang, ZhouSuo; Zi, YanYang; He, ZhengJia; Sun, Chuang

    2013-10-01

    Detecting transient vibration signatures is of vital importance for vibration-based condition monitoring and fault detection of the rotating machinery. However, raw mechanical signals collected by vibration sensors are generally mixtures of physical vibrations of the multiple mechanical components installed in the examined machinery. Fault-generated incipient vibration signatures masked by interfering contents are difficult to be identified. The fast kurtogram (FK) is a concise and smart gadget for characterizing these vibration features. The multi-rate filter-bank (MRFB) and the spectral kurtosis (SK) indicator of the FK are less powerful when strong interfering vibration contents exist, especially when the FK are applied to vibration signals of short duration. It is encountered that the impulsive interfering contents not authentically induced by mechanical faults complicate the optimal analyzing process and lead to incorrect choosing of the optimal analysis subband, therefore the original FK may leave out the essential fault signatures. To enhance the analyzing performance of FK for industrial applications, an improved version of fast kurtogram, named as "fast spatial-spectral ensemble kurtosis kurtogram", is presented. In the proposed technique, discrete quasi-analytic wavelet tight frame (QAWTF) expansion methods are incorporated as the detection filters. The QAWTF, constructed based on dual tree complex wavelet transform, possesses better vibration transient signature extracting ability and enhanced time-frequency localizability compared with conventional wavelet packet transforms (WPTs). Moreover, in the constructed QAWTF, a non-dyadic ensemble wavelet subband generating strategy is put forward to produce extra wavelet subbands that are capable of identifying fault features located in transition-band of WPT. On the other hand, an enhanced signal impulsiveness evaluating indicator, named "spatial-spectral ensemble kurtosis" (SSEK), is put forward and utilized

  14. Modularizing Spatial Ontologies for Assisted Living Systems

    NASA Astrophysics Data System (ADS)

    Hois, Joana

    Assisted living systems are intended to support daily-life activities in user homes by automatizing and monitoring behavior of the environment while interacting with the user in a non-intrusive way. The knowledge base of such systems therefore has to define thematically different aspects of the environment mostly related to space, such as basic spatial floor plan information, pieces of technical equipment in the environment and their functions and spatial ranges, activities users can perform, entities that occur in the environment, etc. In this paper, we present thematically different ontologies, each of which describing environmental aspects from a particular perspective. The resulting modular structure allows the selection of application-specific ontologies as necessary. This hides information and reduces complexity in terms of the represented spatial knowledge and reasoning practicability. We motivate and present the different spatial ontologies applied to an ambient assisted living application.

  15. Minimising Mortality in Endangered Raptors Due to Power Lines: The Importance of Spatial Aggregation to Optimize the Application of Mitigation Measures

    PubMed Central

    Guil, Francisco; Fernández-Olalla, Mariana; Moreno-Opo, Rubén; Mosqueda, Ignacio; Gómez, María Elena; Aranda, Antonio; Arredondo, Ángel; Guzmán, José; Oria, Javier; González, Luis Mariano; Margalida, Antoni

    2011-01-01

    Electrocution by power lines is one of the main causes of non-natural mortality in birds of prey. In an area in central Spain, we surveyed 6304 pylons from 333 power lines to determine electrocution rates, environmental and design factors that may influence electrocution and the efficacy of mitigation measures used to minimise electrocution cases. A total of 952 electrocuted raptors, representing 14 different species, were observed. Electrocuted raptors were concentrated in certain areas and the environmental factors associated with increased electrocution events were: greater numbers of prey animals; greater vegetation cover; and shorter distance to roads. The structural elements associated with electrocutions were shorter strings of insulators, one or more phases over the crossarm, cross-shaped design and pylon function. Of the 952 carcasses found, 148 were eagles, including golden eagle (Aquila chrysaetos), Spanish imperial eagle (Aquila adalberti) and Bonelli's eagle (Aquila fasciata). Electrocuted eagles were clustered in smaller areas than other electrocuted raptors. The factors associated with increased eagle electrocution events were: pylons function, shorter strings of insulators, higher slopes surrounding the pylon, and more numerous potential prey animals. Pylons with increased string of insulators had lower raptor electrocution rates than unimproved pylons, although this technique was unsuccessful for eagles. Pylons with cable insulation showed higher electrocution rates than unimproved pylons, both for raptors and eagles, despite this is the most widely used and recommended mitigation measure in several countries. To optimize the application of mitigation measures, our results recommend the substitution of pin-type insulators to suspended ones and elongating the strings of insulators. PMID:22140549

  16. Spatial capture-recapture

    USGS Publications Warehouse

    Royle, J. Andrew; Chandler, Richard B.; Sollmann, Rahel; Gardner, Beth

    2013-01-01

    Spatial Capture-Recapture provides a revolutionary extension of traditional capture-recapture methods for studying animal populations using data from live trapping, camera trapping, DNA sampling, acoustic sampling, and related field methods. This book is a conceptual and methodological synthesis of spatial capture-recapture modeling. As a comprehensive how-to manual, this reference contains detailed examples of a wide range of relevant spatial capture-recapture models for inference about population size and spatial and temporal variation in demographic parameters. Practicing field biologists studying animal populations will find this book to be a useful resource, as will graduate students and professionals in ecology, conservation biology, and fisheries and wildlife management.

  17. Deformable Surface Spatial Light Modulator

    NASA Astrophysics Data System (ADS)

    Hess, K.; Dandliker, R.; Thalmann, R.

    1987-05-01

    A spatial light modulator (SLM) based on a deformable gel surface is presented. It has remarkable optical properties and its construction and operation are comparatively simple. It can be optically addressed through a photoconductor layer. The surface relief pattern is read out by total reflection and a schlieren optical system. The device provides good wavefront quality (X/10 over the whole aperture of 30 x 50 mm2) and has a spatial resolution of 10 line pairs/mm. Contrast ratios for modulation up to 40:1 were measured. The input sensitivity is typically 0.3 mW/cm2. The rise and decay times are both approximately 20 ms. Besides its primary application as a light valve in large screen TV projection, it can be used in optical information processing systems, e.g., as an incoherent-to-coherent transducer. Combined with a CRT, the SLM can be addressed electronically.

  18. Part I: temporal and spatial distribution of multiclass pesticide residues in lake waters of Northern Greece: application of an optimized SPE-UPLC-MS/MS pretreatment and analytical method.

    PubMed

    Kalogridi, Eleni-Chrysoula; Christophoridis, Christophoros; Bizani, Erasmia; Drimaropoulou, Garyfallia; Fytianos, Konstantinos

    2014-06-01

    The present work describes the application of an analytical procedure, utilizing ultra performance liquid chromatography (UPLC) coupled with mass spectrometry instrumentation, for the determination of 253 multiclass pesticides, classified in six different groups. Solid phase extraction was applied for the isolation and pre-concentration of target compounds in water samples. Surface waters of the lakes located in Northern Greece (Volvi, Doirani, and Kerkini), were collected in two time periods (fall/winter 2010 and spring/summer 2011) and analyzed, applying the developed analytical methods. Spatial distribution of detected pesticides was visualized using interpolation methods and geographical information systems (GIS). Pesticides with maximum concentrations were amitrole, propoxur, simazine, chlorpyrifos, carbendazim, triazophos, disulfoton-sulfone, pyridaben, sebuthylazine, terbuthylazine, atrazine, atrazine-desethyl, bensulfuron-methyl, metobromuron, metribuzin, rotenone, pyriproxyfen, and rimsulfuron. In Lake Kerkini, mainly carbamates and triazines were determined at elevated concentrations, near the coastal point of the NW side of the lake. Seasonal variations were strong among the applied pesticide classes and determined concentrations, indicating the contribution of pesticide application patterns and rainfall. Lake Doirani exhibited organophosphate pesticides at higher concentrations mainly at coastal points, while triazines emerged as the main pollutant during spring sampling. Lake Volvi exhibited the highest pesticide concentrations, mostly triazines and ureas at the central part of the lake. The occurrence of extreme values and nonconstant seasonal variations indicated that the concentrations were increased disproportionately during the second sampling, as a result of the varying contribution of pollution sources right after the application period. In all cases, the total concentration of pesticides increased during the second sampling period. PMID

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

    NASA Astrophysics Data System (ADS)

    Wang, J.; Cai, X.

    2007-12-01

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

  20. Parcellating connectivity in spatial maps

    PubMed Central

    Beck, Diane M.; Fei-Fei, Li

    2015-01-01

    A common goal in biological sciences is to model a complex web of connections using a small number of interacting units. We present a general approach for dividing up elements in a spatial map based on their connectivity properties, allowing for the discovery of local regions underlying large-scale connectivity matrices. Our method is specifically designed to respect spatial layout and identify locally-connected clusters, corresponding to plausible coherent units such as strings of adjacent DNA base pairs, subregions of the brain, animal communities, or geographic ecosystems. Instead of using approximate greedy clustering, our nonparametric Bayesian model infers a precise parcellation using collapsed Gibbs sampling. We utilize an infinite clustering prior that intrinsically incorporates spatial constraints, allowing the model to search directly in the space of spatially-coherent parcellations. After showing results on synthetic datasets, we apply our method to both functional and structural connectivity data from the human brain. We find that our parcellation is substantially more effective than previous approaches at summarizing the brain’s connectivity structure using a small number of clusters, produces better generalization to individual subject data, and reveals functional parcels related to known retinotopic maps in visual cortex. Additionally, we demonstrate the generality of our method by applying the same model to human migration data within the United States. This analysis reveals that migration behavior is generally influenced by state borders, but also identifies regional communities which cut across state lines. Our parcellation approach has a wide range of potential applications in understanding the spatial structure of complex biological networks. PMID:25737822

  1. Modeling of Students' Profile and Learning Chronicle with Data Cubes

    ERIC Educational Resources Information Center

    Ola, Ade G.; Bai, Xue; Omojokun, Emmanuel E.

    2014-01-01

    Over the years, companies have relied on On-Line Analytical Processing (OLAP) to answer complex questions relating to issues in business environments such as identifying profitability, trends, correlations, and patterns. This paper addresses the application of OLAP in education and learning. The objective of the research presented in the paper is…

  2. Individual Differences in Spatial Text Processing: High Spatial Ability Can Compensate for Spatial Working Memory Interference

    ERIC Educational Resources Information Center

    Meneghetti, Chiara; Gyselinck, Valerie; Pazzaglia, Francesca; De Beni, Rossana

    2009-01-01

    The present study investigates the relation between spatial ability and visuo-spatial and verbal working memory in spatial text processing. In two experiments, participants listened to a spatial text (Experiments 1 and 2) and a non-spatial text (Experiment 1), at the same time performing a spatial or a verbal concurrent task, or no secondary task.…

  3. Merging OLTP and OLAP - Back to the Future

    NASA Astrophysics Data System (ADS)

    Lehner, Wolfgang

    When the terms "Data Warehousing" and "Online Analytical Processing" were coined in the 1990s by Kimball, Codd, and others, there was an obvious need for separating data and workload for operational transactional-style processing and decision-making implying complex analytical queries over large and historic data sets. Large data warehouse infrastructures have been set up to cope with the special requirements of analytical query answering for multiple reasons: For example, analytical thinking heavily relies on predefined navigation paths to guide the user through the data set and to provide different views on different aggregation levels.Multi-dimensional queries exploiting hierarchically structured dimensions lead to complex star queries at a relational backend, which could hardly be handled by classical relational systems.

  4. Spatial interpolation approach based on IDW with anisotropic spatial structures

    NASA Astrophysics Data System (ADS)

    Li, Jia; Duan, Ping; Sheng, Yehua; Lv, Haiyang

    2015-12-01

    In many interpolation methods, with its simple interpolation principle, Inverse distance weighted (IDW) interpolation is one of the most common interpolation method. There are anisotropic spatial structures with actual geographical spatial phenomenon. When the IDW interpolation is used, anisotropic spatial structures should be considered. Geostatistical theory has a characteristics of exploring anisotropic spatial structures. In this paper, spatial interpolation approach based on IDW with anisotropic spatial structures is proposed. The DEM data is tested in this paper to prove reliability of the IDW interpolation considering anisotropic spatial structures. Experimental results show that IDW interpolation considering anisotropic spatial structures can improve interpolation precision when sampling data has anisotropic spatial structures feature.

  5. Robustness of spatial micronetworks

    NASA Astrophysics Data System (ADS)

    McAndrew, Thomas C.; Danforth, Christopher M.; Bagrow, James P.

    2015-04-01

    Power lines, roadways, pipelines, and other physical infrastructure are critical to modern society. These structures may be viewed as spatial networks where geographic distances play a role in the functionality and construction cost of links. Traditionally, studies of network robustness have primarily considered the connectedness of large, random networks. Yet for spatial infrastructure, physical distances must also play a role in network robustness. Understanding the robustness of small spatial networks is particularly important with the increasing interest in microgrids, i.e., small-area distributed power grids that are well suited to using renewable energy resources. We study the random failures of links in small networks where functionality depends on both spatial distance and topological connectedness. By introducing a percolation model where the failure of each link is proportional to its spatial length, we find that when failures depend on spatial distances, networks are more fragile than expected. Accounting for spatial effects in both construction and robustness is important for designing efficient microgrids and other network infrastructure.

  6. Robustness of spatial micronetworks.

    PubMed

    McAndrew, Thomas C; Danforth, Christopher M; Bagrow, James P

    2015-04-01

    Power lines, roadways, pipelines, and other physical infrastructure are critical to modern society. These structures may be viewed as spatial networks where geographic distances play a role in the functionality and construction cost of links. Traditionally, studies of network robustness have primarily considered the connectedness of large, random networks. Yet for spatial infrastructure, physical distances must also play a role in network robustness. Understanding the robustness of small spatial networks is particularly important with the increasing interest in microgrids, i.e., small-area distributed power grids that are well suited to using renewable energy resources. We study the random failures of links in small networks where functionality depends on both spatial distance and topological connectedness. By introducing a percolation model where the failure of each link is proportional to its spatial length, we find that when failures depend on spatial distances, networks are more fragile than expected. Accounting for spatial effects in both construction and robustness is important for designing efficient microgrids and other network infrastructure. PMID:25974553

  7. The spatial rotator.

    PubMed

    Rasmusson, A; Hahn, U; Larsen, J O; Gundersen, H J G; Jensen, E B Vedel; Nyengaard, J R

    2013-05-01

    This paper presents a new local volume estimator, the spatial rotator, which is based on measurements on a virtual 3D probe, using computer assisted microscopy. The basic design of the probe builds upon the rotator principle which requires only a few manual intersection markings, thus making the spatial rotator fast to use. Since a 3D probe is involved, it is expected that the spatial rotator will be more efficient than the the nucleator and the planar rotator, which are based on measurements in a single plane. An extensive simulation study shows that the spatial rotator may be more efficient than the traditional local volume estimators. Furthermore, the spatial rotator can be seen as a further development of the Cavalieri estimator, which does not require randomization of sectioning or viewing direction. The tissue may thus be sectioned in any arbitrary direction, making it easy to identify the specific tissue region under study. In order to use the spatial rotator in practice, however, it is necessary to be able to identify intersection points between cell boundaries and test rays in a series of parallel focal planes, also at the peripheral parts of the cell boundaries. In cases where over- and underprojection phenomena are not negligible, they should therefore be corrected for if the spatial rotator is to be applied. If such a correction is not possible, it is needed to avoid these phenomena by using microscopy with increased resolution in the focal plane. PMID:23488880

  8. Children's Spatial Thinking: Does Talk about the Spatial World Matter?

    ERIC Educational Resources Information Center

    Pruden, Shannon M.; Levine, Susan C.; Huttenlocher, Janellen

    2011-01-01

    In this paper we examine the relations between parent spatial language input, children's own production of spatial language, and children's later spatial abilities. Using a longitudinal study design, we coded the use of spatial language (i.e. words describing the spatial features and properties of objects; e.g. big, tall, circle, curvy, edge) from…

  9. Bootstrap percolation on spatial networks

    NASA Astrophysics Data System (ADS)

    Gao, Jian; Zhou, Tao; Hu, Yanqing

    2015-10-01

    Bootstrap percolation is a general representation of some networked activation process, which has found applications in explaining many important social phenomena, such as the propagation of information. Inspired by some recent findings on spatial structure of online social networks, here we study bootstrap percolation on undirected spatial networks, with the probability density function of long-range links’ lengths being a power law with tunable exponent. Setting the size of the giant active component as the order parameter, we find a parameter-dependent critical value for the power-law exponent, above which there is a double phase transition, mixed of a second-order phase transition and a hybrid phase transition with two varying critical points, otherwise there is only a second-order phase transition. We further find a parameter-independent critical value around -1, about which the two critical points for the double phase transition are almost constant. To our surprise, this critical value -1 is just equal or very close to the values of many real online social networks, including LiveJournal, HP Labs email network, Belgian mobile phone network, etc. This work helps us in better understanding the self-organization of spatial structure of online social networks, in terms of the effective function for information spreading.

  10. Bootstrap percolation on spatial networks

    PubMed Central

    Gao, Jian; Zhou, Tao; Hu, Yanqing

    2015-01-01

    Bootstrap percolation is a general representation of some networked activation process, which has found applications in explaining many important social phenomena, such as the propagation of information. Inspired by some recent findings on spatial structure of online social networks, here we study bootstrap percolation on undirected spatial networks, with the probability density function of long-range links’ lengths being a power law with tunable exponent. Setting the size of the giant active component as the order parameter, we find a parameter-dependent critical value for the power-law exponent, above which there is a double phase transition, mixed of a second-order phase transition and a hybrid phase transition with two varying critical points, otherwise there is only a second-order phase transition. We further find a parameter-independent critical value around −1, about which the two critical points for the double phase transition are almost constant. To our surprise, this critical value −1 is just equal or very close to the values of many real online social networks, including LiveJournal, HP Labs email network, Belgian mobile phone network, etc. This work helps us in better understanding the self-organization of spatial structure of online social networks, in terms of the effective function for information spreading. PMID:26423347

  11. Entropy, complexity, and spatial information

    NASA Astrophysics Data System (ADS)

    Batty, Michael; Morphet, Robin; Masucci, Paolo; Stanilov, Kiril

    2014-10-01

    We pose the central problem of defining a measure of complexity, specifically for spatial systems in general, city systems in particular. The measures we adopt are based on Shannon's (in Bell Syst Tech J 27:379-423, 623-656, 1948) definition of information. We introduce this measure and argue that increasing information is equivalent to increasing complexity, and we show that for spatial distributions, this involves a trade-off between the density of the distribution and the number of events that characterize it; as cities get bigger and are characterized by more events—more places or locations, information increases, all other things being equal. But sometimes the distribution changes at a faster rate than the number of events and thus information can decrease even if a city grows. We develop these ideas using various information measures. We first demonstrate their applicability to various distributions of population in London over the last 100 years, then to a wider region of London which is divided into bands of zones at increasing distances from the core, and finally to the evolution of the street system that characterizes the built-up area of London from 1786 to the present day. We conclude by arguing that we need to relate these measures to other measures of complexity, to choose a wider array of examples, and to extend the analysis to two-dimensional spatial systems.

  12. Entropy, complexity, and spatial information

    NASA Astrophysics Data System (ADS)

    Batty, Michael; Morphet, Robin; Masucci, Paolo; Stanilov, Kiril

    2014-09-01

    We pose the central problem of defining a measure of complexity, specifically for spatial systems in general, city systems in particular. The measures we adopt are based on Shannon's (in Bell Syst Tech J 27:379-423, 623-656, 1948) definition of information. We introduce this measure and argue that increasing information is equivalent to increasing complexity, and we show that for spatial distributions, this involves a trade-off between the density of the distribution and the number of events that characterize it; as cities get bigger and are characterized by more events—more places or locations, information increases, all other things being equal. But sometimes the distribution changes at a faster rate than the number of events and thus information can decrease even if a city grows. We develop these ideas using various information measures. We first demonstrate their applicability to various distributions of population in London over the last 100 years, then to a wider region of London which is divided into bands of zones at increasing distances from the core, and finally to the evolution of the street system that characterizes the built-up area of London from 1786 to the present day. We conclude by arguing that we need to relate these measures to other measures of complexity, to choose a wider array of examples, and to extend the analysis to two-dimensional spatial systems.

  13. Spatially branched hierarchical ZnO nanorod-TiO2 nanotube array heterostructures for versatile photocatalytic and photoelectrocatalytic applications: towards intimate integration of 1D-1D hybrid nanostructures.

    PubMed

    Xiao, Fang-Xing; Hung, Sung-Fu; Tao, Hua Bing; Miao, Jianwei; Yang, Hong Bin; Liu, Bin

    2014-12-21

    Hierarchically ordered ZnO nanorods (NRs) decorated nanoporous-layer-covered TiO2 nanotube array (ZnO NRs/NP-TNTAs) nanocomposites have been prepared by an efficient, two-step anodization route combined with an electrochemical deposition strategy, by which monodispersed one-dimensional (1D) ZnO NRs were uniformly grown on the framework of NP-TNTAs. The crystal phases, morphologies, optical properties, photocatalytic as well as photoelectrocatalytic performances of the well-defined ZnO NRs/NP-TNTAs heterostructures were systematically explored to clarify the structure-property correlation. It was found that the ZnO NRs/NP-TNTAs heterostructure exhibits significantly enhanced photocatalytic and photoelectrocatalytic performances, along with favorable photostability toward degradation of organic pollutants under UV light irradiation, as compared to the single component counterparts. The remarkably enhanced photoactivity of ZnO NRs/NP-TNTAs heterostructure is ascribed to the intimate interfacial integration between ZnO NRs and NP-TNTAs substrate imparted by the unique spatially branched hierarchical structure, thereby contributing to the efficient transfer and separation of photogenerated electron-hole charge carriers. Moreover, the specific active species during the photocatalytic process was unambiguously determined and photocatalytic mechanism was tentatively presented. It is anticipated that our work could provide new insights for the construction of various hierarchical 1D-1D hybrid nanocomposites for extensive photocatalytic applications. PMID:25363649

  14. Spatial Light Amplifier Modulators

    NASA Technical Reports Server (NTRS)

    Eng, Sverre T.; Olsson, N. Anders

    1992-01-01

    Spatial light amplifier modulators (SLAM's) are conceptual devices that effect two-dimensional spatial modulation in optical computing and communication systems. Unlike current spatial light modulators, these provide gain. Optical processors incorporating SLAM's designed to operate in reflection or transmission mode. Each element of planar SLAM array is optical amplifier - surface-emitting diode laser. Array addressed electrically with ac modulating signals superimposed on dc bias currents supplied to lasers. SLAM device provides both desired modulation and enough optical gain to enable splitting of output signal into many optical fibers without excessive loss of power.

  15. Electromagnetic spatial coherence wavelets.

    PubMed

    Castaneda, Roman; Garcia-Sucerquia, Jorge

    2006-01-01

    The recently introduced concept of spatial coherence wavelets is generalized to describe the propagation of electromagnetic fields in the free space. For this aim, the spatial coherence wavelet tensor is introduced as an elementary amount, in terms of which the formerly known quantities for this domain can be expressed. It allows for the analysis of the relationship between the spatial coherence properties and the polarization state of the electromagnetic wave. This approach is completely consistent with the recently introduced unified theory of coherence and polarization for random electromagnetic beams, but it provides further insight about the causal relationship between the polarization states at different planes along the propagation path. PMID:16478063

  16. Quantify spatial relations to discover handwritten graphical symbols

    NASA Astrophysics Data System (ADS)

    Li, Jinpeng; Mouchère, Harold; Viard-Gaudin, Christian

    2012-01-01

    To model a handwritten graphical language, spatial relations describe how the strokes are positioned in the 2-dimensional space. Most of existing handwriting recognition systems make use of some predefined spatial relations. However, considering a complex graphical language, it is hard to express manually all the spatial relations. Another possibility would be to use a clustering technique to discover the spatial relations. In this paper, we discuss how to create a relational graph between strokes (nodes) labeled with graphemes in a graphical language. Then we vectorize spatial relations (edges) for clustering and quantization. As the targeted application, we extract the repetitive sub-graphs (graphical symbols) composed of graphemes and learned spatial relations. On two handwriting databases, a simple mathematical expression database and a complex flowchart database, the unsupervised spatial relations outperform the predefined spatial relations. In addition, we visualize the frequent patterns on two text-lines containing Chinese characters.

  17. Spatial Data Supply Chains

    NASA Astrophysics Data System (ADS)

    Varadharajulu, P.; Azeem Saqiq, M.; Yu, F.; McMeekin, D. A.; West, G.; Arnold, L.; Moncrieff, S.

    2015-06-01

    This paper describes current research into the supply of spatial data to the end user in as close to real time as possible via the World Wide Web. The Spatial Data Infrastructure paradigm has been discussed since the early 1990s. The concept has evolved significantly since then but has almost always examined data from the perspective of the supplier. It has been a supplier driven focus rather than a user driven focus. The current research being conducted is making a paradigm shift and looking at the supply of spatial data as a supply chain, similar to a manufacturing supply chain in which users play a significant part. A comprehensive consultation process took place within Australia and New Zealand incorporating a large number of stakeholders. Three research projects that have arisen from this consultation process are examining Spatial Data Supply Chains within Australia and New Zealand and are discussed within this paper.

  18. Spatial Visualizing in Children

    ERIC Educational Resources Information Center

    Smothergill, Daniel W.; And Others

    1975-01-01

    Reports four experiments with preschool and elementary school children. The first study involved a localization task and the remaining three required the mental manipulation of spatial information. (Author/SDH)

  19. Geologic spatial analysis

    SciTech Connect

    Thiessen, R.L.; Eliason, J.R.

    1989-01-01

    This report describes the development of geologic spatial analysis research which focuses on conducting comprehensive three-dimensional analysis of regions using geologic data sets that can be referenced by latitude, longitude, and elevation/depth. (CBS)

  20. Bibliography of spatial interferometry in optical astronomy

    NASA Technical Reports Server (NTRS)

    Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude

    1990-01-01

    The Bibliography of Spatial Interferometry in Optical Astronomy is a guide to the published literature in applications of spatial interferometry techniques to astronomical observations, theory and instrumentation at visible and infrared wavelengths. The key words spatial and optical define the scope of this discipline, distinguishing it from spatial interferometry at radio wavelengths, interferometry in the frequency domain applied to spectroscopy, or more general electro-optics theoretical and laboratory research. The main bibliography is a listing of all technical articles published in the international scientific literature and presented at the major international meetings and workshops attended by the spatial interferometry community. Section B summarizes publications dealing with the basic theoretical concepts and algorithms proposed and applied to optical spatial interferometry and imaging through a turbulent atmosphere. The section on experimental techniques is divided into twelve categories, representing the most clearly identified major areas of experimental research work. Section D, Observations, identifies publications dealing specifically with observations of astronomical sources, in which optical spatial interferometry techniques have been applied.

  1. Bibliography of spatial interferometry in optical astronomy

    NASA Astrophysics Data System (ADS)

    Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude

    1990-02-01

    The Bibliography of Spatial Interferometry in Optical Astronomy is a guide to the published literature in applications of spatial interferometry techniques to astronomical observations, theory and instrumentation at visible and infrared wavelengths. The key words spatial and optical define the scope of this discipline, distinguishing it from spatial interferometry at radio wavelengths, interferometry in the frequency domain applied to spectroscopy, or more general electro-optics theoretical and laboratory research. The main bibliography is a listing of all technical articles published in the international scientific literature and presented at the major international meetings and workshops attended by the spatial interferometry community. Section B summarizes publications dealing with the basic theoretical concepts and algorithms proposed and applied to optical spatial interferometry and imaging through a turbulent atmosphere. The section on experimental techniques is divided into twelve categories, representing the most clearly identified major areas of experimental research work. Section D, Observations, identifies publications dealing specifically with observations of astronomical sources, in which optical spatial interferometry techniques have been applied.

  2. Navigation in spatial networks: A survey

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Chen, Shengyong; Wang, Wanliang

    2014-01-01

    The study on the navigation process in spatial networks has attracted much attention in recent years due to the universal applications in real communication networks. This article surveys recent advances of the navigation problem in spatial networks. Due to the ability to overcome scaling limitations in utilizing geometric information for designing navigation algorithms in spatial networks, we summarize here several important navigation algorithms based on geometric information on both homogeneous and heterogeneous spatial networks. Due to the geometric distance employed, the cost associated with the lengths of additional long-range connections is also taken into account in this survey. Therefore, some contributions reporting how the distribution of long-range links’ lengths affects the average navigation time are summarized. We also briefly discuss two other related processes, i.e. the random walk process and the transportation process. Finally, a few open discussions are included at the end of this survey.

  3. A spatial light modulator for terahertz beams

    SciTech Connect

    Chen, Hou-tong; Taylor, Antoinette J

    2009-01-01

    Spatial light modulators that control the spatial transmission of a terahertz beam either electrically or optically, have been difficult to build due to the lack of suitable materials. Here we propose the use of active terahertz metamaterials for the construction of a multi-pixel spatial modulator for terahertz beams. Our first-generation device consists of a 4 x 4 pixel array, where each pixel is an array of sub-wavelength-sized split-ring resonator elements fabricated on a semiconductor substrate, and is independently controlled by applying an external voltage. Through terahertz transmission experiments, we show that the spatial modulator has a uniform modulation depth of around 40 percent across all pixels at the resonant frequency. Around this operating frequency, the crosstalk between pixels is negligible. This device can operate under small voltage levels, at room temperature, with low power consumption and reasonably high switching speed, and can therefore benefit future applications in terahertz imaging and communications.

  4. Architectural Implications for Spatial Object Association Algorithms

    SciTech Connect

    Kumar, V S; Kurc, T; Saltz, J; Abdulla, G; Kohn, S R; Matarazzo, C

    2009-01-29

    Spatial object association, also referred to as cross-match of spatial datasets, is the problem of identifying and comparing objects in two or more datasets based on their positions in a common spatial coordinate system. In this work, we evaluate two crossmatch algorithms that are used for astronomical sky surveys, on the following database system architecture configurations: (1) Netezza Performance Server R, a parallel database system with active disk style processing capabilities, (2) MySQL Cluster, a high-throughput network database system, and (3) a hybrid configuration consisting of a collection of independent database system instances with data replication support. Our evaluation provides insights about how architectural characteristics of these systems affect the performance of the spatial crossmatch algorithms. We conducted our study using real use-case scenarios borrowed from a large-scale astronomy application known as the Large Synoptic Survey Telescope (LSST).

  5. Architectural Implications for Spatial Object Association Algorithms*

    PubMed Central

    Kumar, Vijay S.; Kurc, Tahsin; Saltz, Joel; Abdulla, Ghaleb; Kohn, Scott R.; Matarazzo, Celeste

    2013-01-01

    Spatial object association, also referred to as crossmatch of spatial datasets, is the problem of identifying and comparing objects in two or more datasets based on their positions in a common spatial coordinate system. In this work, we evaluate two crossmatch algorithms that are used for astronomical sky surveys, on the following database system architecture configurations: (1) Netezza Performance Server®, a parallel database system with active disk style processing capabilities, (2) MySQL Cluster, a high-throughput network database system, and (3) a hybrid configuration consisting of a collection of independent database system instances with data replication support. Our evaluation provides insights about how architectural characteristics of these systems affect the performance of the spatial crossmatch algorithms. We conducted our study using real use-case scenarios borrowed from a large-scale astronomy application known as the Large Synoptic Survey Telescope (LSST). PMID:25692244

  6. Spatial Heterogeneity in the Tumor Microenvironment.

    PubMed

    Yuan, Yinyin

    2016-01-01

    Recent developments in studies of tumor heterogeneity have provoked new thoughts on cancer management. There is a desperate need to understand influence of the tumor microenvironment on cancer development and evolution. Applying principles and quantitative methods from ecology can suggest novel solutions to fulfil this need. We discuss spatial heterogeneity as a fundamental biological feature of the microenvironment, which has been largely ignored. Histological samples can provide spatial context of diverse cell types coexisting within the microenvironment. Advanced computer-vision techniques have been developed for spatial mapping of cells in histological samples. This has enabled the applications of experimental and analytical tools from ecology to cancer research, generating system-level knowledge of microenvironmental spatial heterogeneity. We focus on studies of immune infiltrate and tumor resource distribution, and highlight statistical approaches for addressing the emerging challenges based on these new approaches. PMID:27481837

  7. Arbitrary manipulation of spatial amplitude and phase using phase-only spatial light modulators

    PubMed Central

    Zhu, Long; Wang, Jian

    2014-01-01

    Spatial structure of a light beam is an important degree of freedom to be extensively explored. By designing simple configurations with phase-only spatial light modulators (SLMs), we show the ability to arbitrarily manipulate the spatial full field information (i.e. amplitude and phase) of a light beam. Using this approach to facilitating arbitrary and independent control of spatial amplitude and phase, one can flexibly generate different special kinds of light beams for different specific applications. Multiple collinear orbital angular momentum (OAM) beams, Laguerre-Gaussian (LG) beams, and Bessel beams, having both spatial amplitude and phase distributions, are successfully generated in the experiments. Some arbitrary beams with odd-shaped intensity are also generated in the experiments. PMID:25501584

  8. Spatial decision support system for tobacco enterprise based on spatial data mining

    NASA Astrophysics Data System (ADS)

    Mei, Xin; Liu, Junyi; Zhang, Xuexia; Cui, Weihong

    2007-11-01

    Tobacco enterprise is a special enterprise, which has strong correlation to regional geography. But in the past research and application, the combination between tobacco and GIS is limited to use digital maps to assist cigarette distribution. How to comprehensively import 3S technique and spatial data mining (SDM) to construct spatial decision support system (SDSS) of tobacco enterprise is the main research aspect in this paper. The paper concretely analyzes the GIS requirements in tobacco enterprise for planning location of production, monitoring production management and product sale at the beginning. Then holistic solution is presented and frame design for tobacco enterprise spatial decision based on SDM is given. This paper describes how to use spatial analysis and data mining to realize the spatial decision processing such as monitoring tobacco planted acreage, analyzing and planning the cigarette sale network and so on.

  9. Extreme Learning Machines for spatial environmental data

    NASA Astrophysics Data System (ADS)

    Leuenberger, Michael; Kanevski, Mikhail

    2015-12-01

    The use of machine learning algorithms has increased in a wide variety of domains (from finance to biocomputing and astronomy), and nowadays has a significant impact on the geoscience community. In most real cases geoscience data modelling problems are multivariate, high dimensional, variable at several spatial scales, and are generated by non-linear processes. For such complex data, the spatial prediction of continuous (or categorical) variables is a challenging task. The aim of this paper is to investigate the potential of the recently developed Extreme Learning Machine (ELM) for environmental data analysis, modelling and spatial prediction purposes. An important contribution of this study deals with an application of a generic self-consistent methodology for environmental data driven modelling based on Extreme Learning Machine. Both real and simulated data are used to demonstrate applicability of ELM at different stages of the study to understand and justify the results.

  10. Diffusion on spatial network

    NASA Astrophysics Data System (ADS)

    Hui, Zi; Tang, Xiaoyue; Li, Wei; Greneche, Jean-Marc; Wang, Qiuping A.

    2015-04-01

    In this work, we study the problem of diffusing a product (idea, opinion, disease etc.) among agents on spatial network. The network is constructed by random addition of nodes on the planar. The probability for a previous node to be connected to the new one is inversely proportional to their spatial distance to the power of α. The diffusion rate between two connected nodes is inversely proportional to their spatial distance to the power of β as well. Inspired from the Fick's first law, we introduce the diffusion coefficient to measure the diffusion ability of the spatial network. Using both theoretical analysis and Monte Carlo simulation, we get the fact that the diffusion coefficient always decreases with the increasing of parameter α and β, and the diffusion sub-coefficient follows the power-law of the spatial distance with exponent equals to -α-β+2. Since both short-range diffusion and long-range diffusion exist, we use anomalous diffusion method in diffusion process. We get the fact that the slope index δ in anomalous diffusion is always smaller that 1. The diffusion process in our model is sub-diffusion.

  11. Spatial Knowledge Capture Library

    Energy Science and Technology Software Center (ESTSC)

    2005-05-16

    The Spatial Knowledge Capture Library is a set of algorithms to capture regularities in shapes and trajectories through space and time. We have applied Spatial Knowledge Capture to model the actions of human experts in spatial domains, such as an AWACS Weapons Director task simulation. The library constructs a model to predict the expert’s response to sets of changing cues, such as the movements and actions of adversaries on a battlefield, The library includes amore » highly configurable feature extraction functionality, which supports rapid experimentation to discover causative factors. We use k-medoid clustering to group similar episodes of behavior, and construct a Markov model of system state transitions induced by agents’ actions.« less

  12. The Spatial Standard Observer

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Ahumada, Albert J, Jr.

    2006-01-01

    The spatial standard observer is a computational model that provides a measure of the visibility of a target in a uniform background image or of the visual discriminability of two images. Standard observers have long been used in science and industry to quantify the discriminability of colors. Color standard observers address the spectral characteristics of visual stimuli, while the spatial standard observer (SSO), as its name indicates, addresses spatial characteristics. The SSO is based on a model of human vision. The SSO was developed in a process that included evaluation of a number of earlier mathematical models that address optical, physiological, and psychophysical aspects of spatial characteristics of human visual perception. Elements of the prior models are incorporated into the SSO, which is formulated as a compromise between accuracy and simplicity. The SSO operates on a digitized monochrome still image or on a pair of such images. The SSO consists of three submodels that operate sequentially on the input image(s): 1. A contrast model, which converts an input monochrome image to a luminance contrast image, wherein luminance values are expressed as excursions from, and normalized to, a mean; 2. A contrast-sensitivity-filter model that includes an oblique-effect filter (which accounts for the decline in contrast sensitivity at oblique viewing angles); and 3. A spatial summation model, in which responses are spatially pooled by raising each pixel to the power beta, adding the results, and raising the sum to the 1/b power. In this model, b=2.9 was found to be a suitable value. The net effect of the SSO is to compute a numerical measure of the perceptual strength of the single image, or of the visible difference (denoted the perceptual distance) between two images. The unit of a measure used in the SSO is the just noticeable difference (JND), which is a standard measure of perceptual discriminability. A target that is just visible has a measure of 1 JND.

  13. Embodied spatial cognition.

    PubMed

    Trafton, J Gregory; Harrison, Anthony M

    2011-10-01

    We present a spatial system called Specialized Egocentrically Coordinated Spaces embedded in an embodied cognitive architecture (ACT-R Embodied). We show how the spatial system works by modeling two different developmental findings: gaze-following and Level 1 perspective taking. The gaze-following model is based on an experiment by Corkum and Moore (1998), whereas the Level 1 visual perspective-taking model is based on an experiment by Moll and Tomasello (2006). The models run on an embodied robotic system. PMID:25164505

  14. Spatial fluctuation theorem

    NASA Astrophysics Data System (ADS)

    Pérez-Espigares, Carlos; Redig, Frank; Giardinà, Cristian

    2015-08-01

    For non-equilibrium systems of interacting particles and for interacting diffusions in d-dimensions, a novel fluctuation relation is derived. The theorem establishes a quantitative relation between the probabilities of observing two current values in different spatial directions. The result is a consequence of spatial symmetries of the microscopic dynamics, generalizing in this way the Gallavotti-Cohen fluctuation theorem related to the time-reversal symmetry. This new perspective opens up the possibility of direct experimental measurements of fluctuation relations of vectorial observables.

  15. Spatial reconstruction of single-cell gene expression

    PubMed Central

    Satija, Rahul; Farrell, Jeffrey A.; Gennert, David; Schier, Alexander F.; Regev, Aviv

    2015-01-01

    Spatial localization is a key determinant of cellular fate and behavior, but spatial RNA assays traditionally rely on staining for a limited number of RNA species. In contrast, single-cell RNA-seq allows for deep profiling of cellular gene expression, but established methods separate cells from their native spatial context. Here we present Seurat, a computational strategy to infer cellular localization by integrating single-cell RNA-seq data with in situ RNA patterns. We applied Seurat to spatially map 851 single cells from dissociated zebrafish (Danio rerio) embryos, inferring a transcriptome-wide map of spatial patterning. We confirmed Seurat’s accuracy using several experimental approaches, and used it to identify a set of archetypal expression patterns and spatial markers. Additionally, Seurat correctly localizes rare subpopulations, accurately mapping both spatially restricted and scattered groups. Seurat will be applicable to mapping cellular localization within complex patterned tissues in diverse systems. PMID:25867923

  16. Heredity Factors in Spatial Visualization.

    ERIC Educational Resources Information Center

    Vandenberg, S. G.

    Spatial visualization is not yet clearly understood. Some researchers have concluded that two factors or abilities are involved, spatial orientation and spatial visualization. Different definitions and different tests have been proposed for these two abilities. Several studies indicate that women generally perform more poorly on spatial tests than…

  17. Chunking in Spatial Memory

    ERIC Educational Resources Information Center

    Sargent, Jesse; Dopkins, Stephen; Philbeck, John; Chichka, David

    2010-01-01

    In order to gain insight into the nature of human spatial representations, the current study examined how those representations are affected by blind rotation. Evidence was sought on the possibility that whereas certain environmental aspects may be updated independently of one another, other aspects may be grouped (or chunked) together and updated…

  18. Handbook of Spatial Cognition

    ERIC Educational Resources Information Center

    Waller, David, Ed.; Nadel, Lynn, Ed.

    2012-01-01

    Spatial cognition is a branch of cognitive psychology that studies how people acquire and use knowledge about their environment to determine where they are, how to obtain resources, and how to find their way home. Researchers from a wide range of disciplines, including neuroscience, cognition, and sociology, have discovered a great deal about how…

  19. Grounded spatial belief revision.

    PubMed

    Nejasmic, Jelica; Bucher, Leandra; Knauff, Markus

    2015-05-01

    Beliefs frequently undergo revisions, especially when new pieces of information are true but inconsistent with current beliefs. In previous studies, we showed that linguistic asymmetries provided by relational statements, play a crucial role in spatial belief revision. Located objects (LO) are preferably revised compared to reference objects (RO), known as the LO-principle. Here we establish a connection between spatial belief revision and grounded cognition. In three experiments, we explored whether imagined physical object properties influence which object is relocated and which remains at its initial position. Participants mentally revised beliefs about the arrangements of objects which could be envisaged as light and heavy (Experiment 1), small and large (Experiment 2), or movable and immovable (Experiment 3). The results show that intrinsic object properties are differently taken into account during spatial belief revision. Object weight did not alter the LO-principle (Experiment 1), whereas object size was found to influence which object was preferably relocated (Experiment 2). Object movability did not affect relocation preferences but had an effect on relocation durations (Experiment 3). The findings support the simulation hypothesis within the grounded cognition approach and create new connections between the spatial mental model theory of reasoning and the idea of grounded cognition. PMID:25796056

  20. Bayesian Spatial Quantile Regression

    PubMed Central

    Reich, Brian J.; Fuentes, Montserrat; Dunson, David B.

    2013-01-01

    Tropospheric ozone is one of the six criteria pollutants regulated by the United States Environmental Protection Agency under the Clean Air Act and has been linked with several adverse health effects, including mortality. Due to the strong dependence on weather conditions, ozone may be sensitive to climate change and there is great interest in studying the potential effect of climate change on ozone, and how this change may affect public health. In this paper we develop a Bayesian spatial model to predict ozone under different meteorological conditions, and use this model to study spatial and temporal trends and to forecast ozone concentrations under different climate scenarios. We develop a spatial quantile regression model that does not assume normality and allows the covariates to affect the entire conditional distribution, rather than just the mean. The conditional distribution is allowed to vary from site-to-site and is smoothed with a spatial prior. For extremely large datasets our model is computationally infeasible, and we develop an approximate method. We apply the approximate version of our model to summer ozone from 1997–2005 in the Eastern U.S., and use deterministic climate models to project ozone under future climate conditions. Our analysis suggests that holding all other factors fixed, an increase in daily average temperature will lead to the largest increase in ozone in the Industrial Midwest and Northeast. PMID:23459794

  1. Bayesian Spatial Quantile Regression.

    PubMed

    Reich, Brian J; Fuentes, Montserrat; Dunson, David B

    2011-03-01

    Tropospheric ozone is one of the six criteria pollutants regulated by the United States Environmental Protection Agency under the Clean Air Act and has been linked with several adverse health effects, including mortality. Due to the strong dependence on weather conditions, ozone may be sensitive to climate change and there is great interest in studying the potential effect of climate change on ozone, and how this change may affect public health. In this paper we develop a Bayesian spatial model to predict ozone under different meteorological conditions, and use this model to study spatial and temporal trends and to forecast ozone concentrations under different climate scenarios. We develop a spatial quantile regression model that does not assume normality and allows the covariates to affect the entire conditional distribution, rather than just the mean. The conditional distribution is allowed to vary from site-to-site and is smoothed with a spatial prior. For extremely large datasets our model is computationally infeasible, and we develop an approximate method. We apply the approximate version of our model to summer ozone from 1997-2005 in the Eastern U.S., and use deterministic climate models to project ozone under future climate conditions. Our analysis suggests that holding all other factors fixed, an increase in daily average temperature will lead to the largest increase in ozone in the Industrial Midwest and Northeast. PMID:23459794

  2. ECOREGION SPATIAL DATABASE

    EPA Science Inventory

    This spatial database contains boundaries and attributes describing Level III ecoregions in EPA Region 8. The ecoregions shown here have been derived from Omernik (1987) and from refinements of Omernik's framework that have been made for other projects. These ongoing or re...

  3. Reconstructing Spatial Distributions from Anonymized Locations

    SciTech Connect

    Horey, James L; Forrest, Stephanie; Groat, Michael

    2012-01-01

    Devices such as mobile phones, tablets, and sensors are often equipped with GPS that accurately report a person's location. Combined with wireless communication, these devices enable a wide range of new social tools and applications. These same qualities, however, leave location-aware applications vulnerable to privacy violations. This paper introduces the Negative Quad Tree, a privacy protection method for location aware applications. The method is broadly applicable to applications that use spatial density information, such as social applications that measure the popularity of social venues. The method employs a simple anonymization algorithm running on mobile devices, and a more complex reconstruction algorithm on a central server. This strategy is well suited to low-powered mobile devices. The paper analyzes the accuracy of the reconstruction method in a variety of simulated and real-world settings and demonstrates that the method is accurate enough to be used in many real-world scenarios.

  4. Crop growth and soil water spatial variability under a variable rate center pivot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precision agriculture has mostly emphasized variable-rate nutrients, seeding, and pesticide applications. More recently, variable-rate irrigation equipment has been developed to explore the potential for managing irrigation spatially. Managing irrigation spatially can enhance water conservation and ...

  5. MAPPING SPATIAL ACCURACY AND ESTIMATING LANDSCAPE INDICATORS FROM THEMATIC LAND COVER MAPS USING FUZZY SET THEORY

    EPA Science Inventory

    The accuracy of thematic map products is not spatially homogenous, but instead variable across most landscapes. Properly analyzing and representing the spatial distribution (pattern) of thematic map accuracy would provide valuable user information for assessing appropriate applic...

  6. Spatial Autocorrelation in Mass Spectrometry Imaging.

    PubMed

    Cassese, Alberto; Ellis, Shane R; Ogrinc Potočnik, Nina; Burgermeister, Elke; Ebert, Matthias; Walch, Axel; van den Maagdenberg, Arn M J M; McDonnell, Liam A; Heeren, Ron M A; Balluff, Benjamin

    2016-06-01

    Mass spectrometry imaging (MSI) is a powerful molecular imaging technique. In microprobe MSI, images are created through a grid-wise interrogation of individual spots by mass spectrometry across a surface. Classical statistical tests for within-sample comparisons fail as close-by measurement spots violate the assumption of independence of these tests, which can lead to an increased false-discovery rate. For spatial data, this effect is referred to as spatial autocorrelation. In this study, we investigated spatial autocorrelation in three different matrix-assisted laser desorption/ionization MSI data sets. These data sets cover different molecular classes (metabolites/drugs, lipids, and proteins) and different spatial resolutions ranging from 20 to 100 μm. Significant spatial autocorrelation was detected in all three data sets and found to increase with decreasing pixel size. To enable statistical testing for differences in mass signal intensities between regions of interest within MSI data sets, we propose the use of Conditional Autoregressive (CAR) models. We show that, by accounting for spatial autocorrelation, discovery rates (i.e., the ratio between the features identified and the total number of features) could be reduced between 21% and 69%. The reliability of this approach was validated by control mass signals based on prior knowledge. In light of the advent of larger MSI data sets based on either an increased spatial resolution or 3D data sets, accounting for effects due to spatial autocorrelation becomes even more indispensable. Here, we propose a generic and easily applicable workflow to enable within-sample statistical comparisons. PMID:27180608

  7. Proximal soil sensing to parameterize spatial environmental modeling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatially explicit models are important tools to understand the effects of the interaction of management and landscape factors on water and soil quality. One challenge to application of such models is the need to know spatially-distributed values for input parameters. Some such data can come from av...

  8. Spatial reasoning in remotely sensed data

    NASA Technical Reports Server (NTRS)

    Campbell, J.; Ehrich, R. W.; Elliott, D.; Haralick, R. M.; Wang, S.

    1981-01-01

    Photointerpreters employ a variety of implicit spatial models to provide interpretations from remotely sensed aerial or satellite imagery. In this paper one application is illustrated: how ridges and valleys can be automatically interpreted from Landsat imagery of a mountainous area, and how a relative elevation terrain model can be constructed from this interpretation. How to examine valleys for the possible presence of streams or rivers is shown, and how a spatial relational model can be set up to make a final interpretation of the river drainage network is explored.

  9. Natural Resources and Spatial Spillovers

    NASA Astrophysics Data System (ADS)

    Batbold, Dulguun

    Regions going through a natural resource boom tend to have higher average incomes and employment relative to the rest of the country. For policy analysis, a question that often needs to be answered is to what extent the economic growth in the extraction region spills over to neighboring areas. This thesis develops a detailed methodology for analyzing the economic effects of geographically localized shocks within the framework of a parsimonious spatial general equilibrium model, including various methods for estimating key parameters. This model-based approach is being offered as a complementary tool for applied researchers conducting economic impact analysis. Existing empirical methods such as input-output analysis or difference-in-difference estimation techniques are often not optimal for analyzing spatially correlated data, and this model-based methodology can be used to overcome their limitations. Another important advantage of this methodology is that it is computationally tractable and has a relatively low data requirement, which can make a particularly big difference in studying developing countries where data quality and availability can often be an insurmountable challenge. Following the exposition of the methodology, this thesis presents two separate applications, one involving a developed nation and the other a developing one. In the first case, the methodology is applied to analyze the economic impact of the shale energy boom that's been occurring in and around Bakken counties in western North Dakota and eastern Montana over the past decade. In the second case, the methodology is used to analyze the economic impact of the Oyu Tolgoi copper-gold mining project in the Southern Gobi region of Mongolia. A common conclusion that is drawn from the two applications mentioned above is that economic booms fueled by natural resource extracting industries are largely local and have limited spillover effects on neighboring regions.

  10. 1985 NAPAP EMISSIONS INVENTORY: DEVELOPMENT OF SPATIAL ALLOCATION FACTORS

    EPA Science Inventory

    The report documents the development and application of spatial allocation factors for the 1985 National Acid Precipitation Assessment program(NAPAP) Emissions Inventory (Version 2). The 1985 annual inventory and related modelers' inventory represent the most comprehensive and hi...

  11. The impact of spatial scales and spatial smoothing on the outcome of bayesian spatial model.

    PubMed

    Kang, Su Yun; McGree, James; Mengersen, Kerrie

    2013-01-01

    Discretization of a geographical region is quite common in spatial analysis. There have been few studies into the impact of different geographical scales on the outcome of spatial models for different spatial patterns. This study aims to investigate the impact of spatial scales and spatial smoothing on the outcomes of modelling spatial point-based data. Given a spatial point-based dataset (such as occurrence of a disease), we study the geographical variation of residual disease risk using regular grid cells. The individual disease risk is modelled using a logistic model with the inclusion of spatially unstructured and/or spatially structured random effects. Three spatial smoothness priors for the spatially structured component are employed in modelling, namely an intrinsic Gaussian Markov random field, a second-order random walk on a lattice, and a Gaussian field with Matérn correlation function. We investigate how changes in grid cell size affect model outcomes under different spatial structures and different smoothness priors for the spatial component. A realistic example (the Humberside data) is analyzed and a simulation study is described. Bayesian computation is carried out using an integrated nested Laplace approximation. The results suggest that the performance and predictive capacity of the spatial models improve as the grid cell size decreases for certain spatial structures. It also appears that different spatial smoothness priors should be applied for different patterns of point data. PMID:24146799

  12. Spatial strategies for managing visitor impacts in National Parks

    USGS Publications Warehouse

    Leung, Y.-F.; Marion, J.L.

    1999-01-01

    effective in minimizing resource impacts. Spatial configuration was only minimally evaluated, as it was not included in the survey. The proposed typology of spatial strategies offers a useful means of organizing and understanding the wide variety of management strategies and actions applied in managing visitor impacts in parks and protected areas. Examples from U.S. national parks demonstrate the diversity of these basic strategies and their flexibility in implementation at various spatial scales. Documentation of these examples helps illustrate their application and inform managers of the multitude of options. Further analysis from the spatial perspective is needed Io extend the applicability of this typology to other recreational activities and management issues.

  13. Dealing with spatial heterogeneity

    NASA Astrophysics Data System (ADS)

    Marsily, Gh.; Delay, F.; Gonçalvès, J.; Renard, Ph.; Teles, V.; Violette, S.

    2005-03-01

    Heterogeneity can be dealt with by defining homogeneous equivalent properties, known as averaging, or by trying to describe the spatial variability of the rock properties from geologic observations and local measurements. The techniques available for these descriptions are mostly continuous Geostatistical models, or discontinuous facies models such as the Boolean, Indicator or Gaussian-Threshold models and the Markov chain model. These facies models are better suited to treating issues of rock strata connectivity, e.g. buried high permeability channels or low permeability barriers, which greatly affect flow and, above all, transport in aquifers. Genetic models provide new ways to incorporate more geology into the facies description, an approach that has been well developed in the oil industry, but not enough in hydrogeology. The conclusion is that future work should be focused on improving the facies models, comparing them, and designing new in situ testing procedures (including geophysics) that would help identify the facies geometry and properties. A world-wide catalog of aquifer facies geometry and properties, which could combine site genesis and description with methods used to assess the system, would be of great value for practical applications. On peut aborder le problème de l'hétérogénéité en s'efforçant de définir une perméabilité équivalente homogène, par prise de moyenne, ou au contraire en décrivant la variation dans l'espace des propriétés des roches à partir des observations géologiques et des mesures locales. Les techniques disponibles pour une telle description sont soit continues, comme l'approche Géostatistique, soit discontinues, comme les modèles de faciès, Booléens, ou bien par Indicatrices ou Gaussiennes Seuillées, ou enfin Markoviens. Ces modèles de faciès sont mieux capables de prendre en compte la connectivité des strates géologiques, telles que les chenaux enfouis à forte perméabilité, ou au contraire les faci

  14. Dealing with spatial heterogeneity

    NASA Astrophysics Data System (ADS)

    Marsily, Gh.; Delay, F.; Gonçalvès, J.; Renard, Ph.; Teles, V.; Violette, S.

    2005-03-01

    Heterogeneity can be dealt with by defining homogeneous equivalent properties, known as averaging, or by trying to describe the spatial variability of the rock properties from geologic observations and local measurements. The techniques available for these descriptions are mostly continuous Geostatistical models, or discontinuous facies models such as the Boolean, Indicator or Gaussian-Threshold models and the Markov chain model. These facies models are better suited to treating issues of rock strata connectivity, e.g. buried high permeability channels or low permeability barriers, which greatly affect flow and, above all, transport in aquifers. Genetic models provide new ways to incorporate more geology into the facies description, an approach that has been well developed in the oil industry, but not enough in hydrogeology. The conclusion is that future work should be focused on improving the facies models, comparing them, and designing new in situ testing procedures (including geophysics) that would help identify the facies geometry and properties. A world-wide catalog of aquifer facies geometry and properties, which could combine site genesis and description with methods used to assess the system, would be of great value for practical applications. On peut aborder le problème de l'hétérogénéité en s'efforçant de définir une perméabilité équivalente homogène, par prise de moyenne, ou au contraire en décrivant la variation dans l'espace des propriétés des roches à partir des observations géologiques et des mesures locales. Les techniques disponibles pour une telle description sont soit continues, comme l'approche Géostatistique, soit discontinues, comme les modèles de faciès, Booléens, ou bien par Indicatrices ou Gaussiennes Seuillées, ou enfin Markoviens. Ces modèles de faciès sont mieux capables de prendre en compte la connectivité des strates géologiques, telles que les chenaux enfouis à forte perméabilité, ou au contraire les faci

  15. The importance of scale for spatial-confounding bias and precision of spatial regression estimators

    PubMed Central

    Paciorek, Christopher J

    2010-01-01

    Residuals in regression models are often spatially correlated. Prominent examples include studies in environmental epidemiology to understand the chronic health effects of pollutants. I consider the effects of residual spatial structure on the bias and precision of regression coefficients, developing a simple framework in which to understand the key issues and derive informative analytic results. When unmeasured confounding introduces spatial structure into the residuals, regression models with spatial random effects and closely-related models such as kriging and penalized splines are biased, even when the residual variance components are known. Analytic and simulation results show how the bias depends on the spatial scales of the covariate and the residual: one can reduce bias by fitting a spatial model only when there is variation in the covariate at a scale smaller than the scale of the unmeasured confounding. I also discuss how the scales of the residual and the covariate affect efficiency and uncertainty estimation when the residuals are independent of the covariate. In an application on the association between black carbon particulate matter air pollution and birth weight, controlling for large-scale spatial variation appears to reduce bias from unmeasured confounders, while increasing uncertainty in the estimated pollution effect. PMID:21528104

  16. Optical vortex array in spatially varying lattice

    NASA Astrophysics Data System (ADS)

    Kapoor, Amit; Kumar, Manish; Senthilkumaran, P.; Joseph, Joby

    2016-04-01

    We present an experimental method based on a modified multiple beam interference approach to generate an optical vortex array arranged in a spatially varying lattice. This method involves two steps which are: numerical synthesis of a consistent phase mask by using two-dimensional integrated phase gradient calculations and experimental implementation of produced phase mask by utilizing a phase only spatial light modulator in an optical 4f Fourier filtering setup. This method enables an independent variation of the orientation and period of the vortex lattice. As working examples, we provide the experimental demonstration of various spatially variant optical vortex lattices. We further confirm the existence of optical vortices by formation of fork fringes. Such lattices may find applications in size dependent trapping, sorting, manipulation and photonic crystals.

  17. Spatial audio through a bone conduction interface.

    PubMed

    MacDonald, Justin A; Henry, Paula P; Letowski, Tomasz R

    2006-10-01

    Headphones are the standard presentation device for radio communication in the military. Although bone conduction devices possess several advantages over headphones for some military applications, they are generally considered inappropriate for inclusion in a multi-channel system. The current study tested the feasibility of a multi-channel bone conduction system by measuring the localizability of spatialized auditory stimuli presented through a pair of bone conduction vibrators. Listeners localized a Gaussian noise stimulus spatialized with individualized head-related transfer functions (HRTFs). The sounds were presented from eight virtual locations on the horizontal plane (0, +/-45, +/-90, +/-135, and 180 degrees ) through either stereo headphones or a stereo bone conduction system. Localization performance was found to be nearly identical for both audio systems, indicating that bone conduction systems can be effectively used for displaying spatial information. PMID:17062501

  18. Some topics in the spatial bispectra

    SciTech Connect

    Sullivan, E.

    1994-11-15

    The bispectrum can be defined as the triple fourier transform of the third order cumulant of a data series. Up to the present, except in image analysis, most work on the bispectrum has treated time series. Recently, however, there has been interest in using the bispectrum in acoustic array processing. After a look at some issues involving sampling frequencies and symmetries of the bispectrum in general, two applications of the spatial bispectrum to underwater acoustic array processing will be discussed. One is a method of processing against loss of spatial coherence in towed arrays, which takes the form of a one-dimensional image, and the other is a look at the role of spatial bispectra in matched-field processing, which is a form of model-based processing used for the localization of acoustic sound sources.

  19. Spatial pattern of diarrhea based on regional economic and environment by spatial autoregressive model

    NASA Astrophysics Data System (ADS)

    Bekti, Rokhana Dwi; Nurhadiyanti, Gita; Irwansyah, Edy

    2014-10-01

    The diarrhea case pattern information, especially for toddler, is very important. It is used to show the distribution of diarrhea in every region, relationship among that locations, and regional economic characteristic or environmental behavior. So, this research uses spatial pattern to perform them. This method includes: Moran's I, Spatial Autoregressive Models (SAR), and Local Indicator of Spatial Autocorrelation (LISA). It uses sample from 23 sub districts of Bekasi Regency, West Java, Indonesia. Diarrhea case, regional economic, and environmental behavior of households have a spatial relationship among sub district. SAR shows that the percentage of Regional Gross Domestic Product is significantly effect on diarrhea at α = 10%. Therefore illiteracy and health center facilities are significant at α = 5%. With LISA test, sub districts in southern Bekasi have high dependencies with Cikarang Selatan, Serang Baru, and Setu. This research also builds development application that is based on java and R to support data analysis.

  20. Particle detector spatial resolution

    DOEpatents

    Perez-Mendez, Victor

    1992-01-01

    Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector.

  1. Spatial Organization of Epigenomes

    PubMed Central

    Dubé, Jonathan Christopher; Wang, Xue Qing David; Dostie, Josée

    2016-01-01

    The role of genome architecture in transcription regulation has become the focus of an increasing number of studies over the past decade. Chromatin organization can have a significant impact on gene expression by promoting or restricting the physical proximity between regulatory DNA elements. Given that any change in chromatin state has the potential to alter DNA folding and the proximity between control elements, the spatial organization of chromatin is inherently linked to its molecular composition. In this review, we explore how modulators of chromatin state and organization might keep gene expression in check. We discuss recent findings and present some of the less well-studied aspects of spatial genome organization such as chromatin dynamics and regulation by non-coding RNAs. PMID:26986719

  2. Spatial Phase Imaging

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Frequently, scientists grow crystals by dissolving a protein in a specific liquid solution, and then allowing that solution to evaporate. The methods used next have been, variously, invasive (adding a dye that is absorbed by the protein), destructive (crushing protein/salt-crystal mixtures and observing differences between the crushing of salt and protein), or costly and time-consuming (X-ray crystallography). In contrast to these methods, a new technology for monitoring protein growth, developed in part through NASA Small Business Innovation Research (SBIR) funding from Marshall Space Flight Center, is noninvasive, nondestructive, rapid, and more cost effective than X-ray analysis. The partner for this SBIR, Photon-X, Inc., of Huntsville, Alabama, developed spatial phase imaging technology that can monitor crystal growth in real time and in an automated mode. Spatial phase imaging scans for flaws quickly and produces a 3-D structured image of a crystal, showing volumetric growth analysis for future automated growth.

  3. Making a Place for Space: Spatial Thinking in Social Science

    PubMed Central

    Logan, John R.

    2013-01-01

    New technologies and multilevel data sets that include geographic identifiers have heightened sociologists’ interest in spatial analysis. I review several of the key concepts, measures, and methods that are brought into play in this work, and offer examples of their application in a variety of substantive fields. I argue that the most effective use of the new tools requires greater emphasis on spatial thinking. A device as simple as an illustrative map requires some understanding of how people respond to visual cues; models as complex as HLM with spatial lags require thoughtful measurement decisions and raise questions about what a spatial effect represents. PMID:24273374

  4. Compatible Spatial Discretizations for Partial Differential Equations

    SciTech Connect

    Arnold, Douglas, N, ed.

    2004-11-25

    From May 11--15, 2004, the Institute for Mathematics and its Applications held a hot topics workshop on Compatible Spatial Discretizations for Partial Differential Equations. The numerical solution of partial differential equations (PDE) is a fundamental task in science and engineering. The goal of the workshop was to bring together a spectrum of scientists at the forefront of the research in the numerical solution of PDEs to discuss compatible spatial discretizations. We define compatible spatial discretizations as those that inherit or mimic fundamental properties of the PDE such as topology, conservation, symmetries, and positivity structures and maximum principles. A wide variety of discretization methods applied across a wide range of scientific and engineering applications have been designed to or found to inherit or mimic intrinsic spatial structure and reproduce fundamental properties of the solution of the continuous PDE model at the finite dimensional level. A profusion of such methods and concepts relevant to understanding them have been developed and explored: mixed finite element methods, mimetic finite differences, support operator methods, control volume methods, discrete differential forms, Whitney forms, conservative differencing, discrete Hodge operators, discrete Helmholtz decomposition, finite integration techniques, staggered grid and dual grid methods, etc. This workshop seeks to foster communication among the diverse groups of researchers designing, applying, and studying such methods as well as researchers involved in practical solution of large scale problems that may benefit from advancements in such discretizations; to help elucidate the relations between the different methods and concepts; and to generally advance our understanding in the area of compatible spatial discretization methods for PDE. Particular points of emphasis included: + Identification of intrinsic properties of PDE models that are critical for the fidelity of numerical

  5. Moment equations in spatial evolutionary ecology.

    PubMed

    Lion, Sébastien

    2016-09-21

    How should we model evolution in spatially structured populations? Here, I review an evolutionary ecology approach based on the technique of spatial moment equations. I first provide a mathematical underpinning to the derivation of equations for the densities of various spatial configurations in network-based models. I then show how this spatial ecological framework can be coupled with an adaptive dynamics approach to compute the invasion fitness of a rare mutant in a resident population at equilibrium. Under the additional assumption that mutations have small phenotypic effects, I show that the selection gradient can be expressed as a function of neutral measures of genetic and demographic structure. I discuss the connections between this approach and inclusive fitness theory, as well as the applicability and limits of this technique. My main message is that spatial moment equations can be used as a means to obtain compact qualitative arguments about the evolution of life-history traits for a variety of life cycles. PMID:26555844

  6. Dynamic Scene Classification Using Redundant Spatial Scenelets.

    PubMed

    Du, Liang; Ling, Haibin

    2016-09-01

    Dynamic scene classification started drawing an increasing amount of research efforts recently. While existing arts mainly rely on low-level features, little work addresses the need of exploring the rich spatial layout information in dynamic scene. Motivated by the fact that dynamic scenes are characterized by both dynamic and static parts with spatial layout priors, we propose to use redundant spatial grouping of a large number of spatiotemporal patches, named scenelet, to represent a dynamic scene. Specifically, each scenelet is associated with a category-dependent scenelet model to encode the likelihood of a specific scene category. All scenelet models for a scene category are jointly learned to encode the spatial interactions and redundancies among them. Subsequently, a dynamic scene sequence is represented as a collection of category likelihoods estimated by these scenelet models. Such presentation effectively encodes the spatial layout prior together with associated semantic information, and can be used for classifying dynamic scenes in combination with a standard learning algorithm such as k -nearest neighbor or linear support vector machine. The effectiveness of our approach is clearly demonstrated using two dynamic scene benchmarks and a related application for violence video classification. In the nearest neighbor classification framework, for dynamic scene classification, our method outperforms previous state-of-the-arts on both Maryland "in the wild" dataset and "stabilized" dynamic scene dataset. For violence video classification on a benchmark dataset, our method achieves a promising classification rate of 87.08%, which significantly improves previous best result of 81.30%. PMID:26302526

  7. Optimization techniques for integrating spatial data

    USGS Publications Warehouse

    Herzfeld, U.C.; Merriam, D.F.

    1995-01-01

    Two optimization techniques ta predict a spatial variable from any number of related spatial variables are presented. The applicability of the two different methods for petroleum-resource assessment is tested in a mature oil province of the Midcontinent (USA). The information on petroleum productivity, usually not directly accessible, is related indirectly to geological, geophysical, petrographical, and other observable data. This paper presents two approaches based on construction of a multivariate spatial model from the available data to determine a relationship for prediction. In the first approach, the variables are combined into a spatial model by an algebraic map-comparison/integration technique. Optimal weights for the map comparison function are determined by the Nelder-Mead downhill simplex algorithm in multidimensions. Geologic knowledge is necessary to provide a first guess of weights to start the automatization, because the solution is not unique. In the second approach, active set optimization for linear prediction of the target under positivity constraints is applied. Here, the procedure seems to select one variable from each data type (structure, isopachous, and petrophysical) eliminating data redundancy. Automating the determination of optimum combinations of different variables by applying optimization techniques is a valuable extension of the algebraic map-comparison/integration approach to analyzing spatial data. Because of the capability of handling multivariate data sets and partial retention of geographical information, the approaches can be useful in mineral-resource exploration. ?? 1995 International Association for Mathematical Geology.

  8. GENERATING SOPHISTICATED SPATIAL SURROGATES USING THE MIMS SPATIAL ALLOCATOR

    EPA Science Inventory

    The Multimedia Integrated Modeling System (MIMS) Spatial Allocator is open-source software for generating spatial surrogates for emissions modeling, changing the map projection of Shapefiles, and performing other types of spatial allocation that does not require the use of a comm...

  9. Spatial symmetry breaking in rapidly rotating convective spherical shells

    NASA Technical Reports Server (NTRS)

    Zhang, Keke; Schubert, Gerald

    1995-01-01

    Many problems in geophysical and astrophysical convection systems are characterized by fast rotation and spherical shell geometry. The combined effects of Coriolis forces and spherical shell geometry produce a unique spatial symmetry for the convection pattern in a rapidly rotating spherical shell. In this paper, we first discuss the general spatial symmetries for rotating spherical shell convection. A special model, a spherical shell heated from below, is then used to illustrate how and when the spatial symmetries are broken. Symmetry breaking occurs via a sequence of spatial transitions from the primary conducting state to the complex multiple-layered columnar structure. It is argued that, because of the dominant effects of rotation, the sequence of spatial transitions identified from this particular model is likely to be generally valid. Applications of the spatial symmetry breaking to planetary convection problems are also discussed.

  10. Different Dimensions of Spatial Ability.

    ERIC Educational Resources Information Center

    Eliot, John; Hauptman, Anna

    1981-01-01

    Indicates that spatial ability describes a variety of different behaviors and briefly reviews efforts to define intelligence factors and identify processes involved in solving tasks requiring spatial ability. (DS)

  11. Robust quantum spatial search

    NASA Astrophysics Data System (ADS)

    Tulsi, Avatar

    2016-07-01

    Quantum spatial search has been widely studied with most of the study focusing on quantum walk algorithms. We show that quantum walk algorithms are extremely sensitive to systematic errors. We present a recursive algorithm which offers significant robustness to certain systematic errors. To search N items, our recursive algorithm can tolerate errors of size O(1{/}√{ln N}) which is exponentially better than quantum walk algorithms for which tolerable error size is only O(ln N{/}√{N}). Also, our algorithm does not need any ancilla qubit. Thus our algorithm is much easier to implement experimentally compared to quantum walk algorithms.

  12. Robust quantum spatial search

    NASA Astrophysics Data System (ADS)

    Tulsi, Avatar

    2016-04-01

    Quantum spatial search has been widely studied with most of the study focusing on quantum walk algorithms. We show that quantum walk algorithms are extremely sensitive to systematic errors. We present a recursive algorithm which offers significant robustness to certain systematic errors. To search N items, our recursive algorithm can tolerate errors of size O(1{/}√{N}) which is exponentially better than quantum walk algorithms for which tolerable error size is only O(ln N{/}√{N}) . Also, our algorithm does not need any ancilla qubit. Thus our algorithm is much easier to implement experimentally compared to quantum walk algorithms.

  13. Spatial Premise Integration in Hindi

    ERIC Educational Resources Information Center

    Mishra, Ramesh Kumar

    2007-01-01

    Spatial reasoning or locating objects in a spatial space has long been an important area of research in cognitive science because analyzing space categorically and finding objects is a fundamental act of mental perception and cognition. Premise integration in tasks of spatial reasoning has recently received considerable research attention. This is…

  14. Contour Integration across Spatial Frequency

    ERIC Educational Resources Information Center

    Persike, Malte; Olzak, Lynn A.; Meinhardt, Gunter

    2009-01-01

    Association field models of contour integration suggest that local band-pass elements are spatially grouped to global contours within limited bands of spatial frequency (Field, Hayes, & Hess, 1993). While results for local orientation and spacing variation render support for AF models, effects of spatial frequency (SF) have rarely been addressed.…

  15. RADSS: an integration of GIS, spatial statistics, and network service for regional data mining

    NASA Astrophysics Data System (ADS)

    Hu, Haitang; Bao, Shuming; Lin, Hui; Zhu, Qing

    2005-10-01

    Regional data mining, which aims at the discovery of knowledge about spatial patterns, clusters or association between regions, has widely applications nowadays in social science, such as sociology, economics, epidemiology, crime, and so on. Many applications in the regional or other social sciences are more concerned with the spatial relationship, rather than the precise geographical location. Based on the spatial continuity rule derived from Tobler's first law of geography: observations at two sites tend to be more similar to each other if the sites are close together than if far apart, spatial statistics, as an important means for spatial data mining, allow the users to extract the interesting and useful information like spatial pattern, spatial structure, spatial association, spatial outlier and spatial interaction, from the vast amount of spatial data or non-spatial data. Therefore, by integrating with the spatial statistical methods, the geographical information systems will become more powerful in gaining further insights into the nature of spatial structure of regional system, and help the researchers to be more careful when selecting appropriate models. However, the lack of such tools holds back the application of spatial data analysis techniques and development of new methods and models (e.g., spatio-temporal models). Herein, we make an attempt to develop such an integrated software and apply it into the complex system analysis for the Poyang Lake Basin. This paper presents a framework for integrating GIS, spatial statistics and network service in regional data mining, as well as their implementation. After discussing the spatial statistics methods involved in regional complex system analysis, we introduce RADSS (Regional Analysis and Decision Support System), our new regional data mining tool, by integrating GIS, spatial statistics and network service. RADSS includes the functions of spatial data visualization, exploratory spatial data analysis, and

  16. An object-oriented spatial data model for virtual geographical environment

    NASA Astrophysics Data System (ADS)

    Wang, Yongjun; Che, Weitao; Cao, Rui; Shen, Jingwei

    2008-10-01

    This paper presents a spatial data model used for modeling geospatial data in virtual geographical environment. Most traditional spatial data modeling approach in geographical information system abstracts physical world with spatial entity and relationship between each other, put emphases on representing spatial feature and their topologies, whilst virtual reality system focus on capacity of keeping vivid rendering, i.e. high fidelity. Taking into account both topological characteristic of spatial data model in GIS and spaghetti characteristic of in VR, We introduce here an integrated spatial data model which could represent both topological and non-topological spatial data and underpin both various spatial analysis functions and real-time rending visualization effectively. This object-oriented method model topological feature separately from geometrical data and links them by a couple link, by which user can access different aspect of spatial data in specific application context. A virtual geographical scene management framework based on above spatial data model is introduced at the last.

  17. Approximate spatial reasoning

    NASA Technical Reports Server (NTRS)

    Dutta, Soumitra

    1988-01-01

    Much of human reasoning is approximate in nature. Formal models of reasoning traditionally try to be precise and reject the fuzziness of concepts in natural use and replace them with non-fuzzy scientific explicata by a process of precisiation. As an alternate to this approach, it has been suggested that rather than regard human reasoning processes as themselves approximating to some more refined and exact logical process that can be carried out with mathematical precision, the essence and power of human reasoning is in its capability to grasp and use inexact concepts directly. This view is supported by the widespread fuzziness of simple everyday terms (e.g., near tall) and the complexity of ordinary tasks (e.g., cleaning a room). Spatial reasoning is an area where humans consistently reason approximately with demonstrably good results. Consider the case of crossing a traffic intersection. We have only an approximate idea of the locations and speeds of various obstacles (e.g., persons and vehicles), but we nevertheless manage to cross such traffic intersections without any harm. The details of our mental processes which enable us to carry out such intricate tasks in such apparently simple manner are not well understood. However, it is that we try to incorporate such approximate reasoning techniques in our computer systems. Approximate spatial reasoning is very important for intelligent mobile agents (e.g., robots), specially for those operating in uncertain or unknown or dynamic domains.

  18. Spatial cyclotron damping

    NASA Technical Reports Server (NTRS)

    Olson, C. L.

    1970-01-01

    To examine spatial electron cyclotron damping in a uniform Vlasov plasma, it is noted that the plasma response to a steady-state transverse excitation consists of several terms (dielectric-pole, free-streaming, and branch-cut), but that the cyclotron-damped pole term is the dominant term for z l = c/w sub ce provided (w sub pe/w sub ce) squared (c/a) is much greater than 1. If the latter inequality does not hold, then the free-streaming and branch-cut terms persist well past z = c/w sub ce as w sub 1 approaches w sub ce, making experimental measurement of cyclotron damping essentially impossible. Considering only (w sub pe/w sub ce) squared (c/a) is much greater than 1, it is shown how collisional effects should be estimated and how a finite-width excitation usually has little effect on the cyclotron-damped part of the response. Criteria is established concerning collisional damping, measurable damping length sizes, and allowed uncertainty in the magnetic field Beta. Results of numerical calculations, showing the regions in the appropriate parameter spaces that meet these criteria, are presented. From these results, one can determine the feasibility of, or propose parameter values for, an experiment designed to measure spatial cyclotron damping. It is concluded that the electron temperature T sub e should be at least 1 ev., and preferably 10 ev. or higher, for a successful experiment.

  19. Spatial Models for Virtual Networks

    NASA Astrophysics Data System (ADS)

    Janssen, Jeannette

    This paper discusses the use of spatial graph models for the analysis of networks that do not have a direct spatial reality, such as web graphs, on-line social networks, or citation graphs. In a spatial graph model, nodes are embedded in a metric space, and link formation depends on the relative position of nodes in the space. It is argued that spatial models form a good basis for link mining: assuming a spatial model, the link information can be used to infer the spatial position of the nodes, and this information can then be used for clustering and recognition of node similarity. This paper gives a survey of spatial graph models, and discusses their suitability for link mining.

  20. Spatial organization of cooperation

    NASA Astrophysics Data System (ADS)

    Desprat, Nicolas

    The structure of the environment spatially confines bacteria inside groups where they live and evolve with their siblings. This population structure may not only select for individual abilities but also for group properties that would eventually enhance the fitness of the colony. In poor media, we might think that maximizing the contact with the environment would maximize the fitness of individual cells. However, we will show that the microcolony of P. aeruginosa adapts its morphogenesis to maximize cell-cell contacts rather than cell-environment interactions when iron becomes scarce in the environment. In this case, reducing the surface of exchange with the environment allows to limit the loss of secreted molecules required to efficiently fetch extracelllular iron at very low concentration.

  1. Spatial cognition and navigation

    NASA Technical Reports Server (NTRS)

    Aretz, Anthony J.

    1989-01-01

    An experiment that provides data for the development of a cognitive model of pilot flight navigation is described. The experiment characterizes navigational awareness as the mental alignment of two frames of reference: (1) the ego centered reference frame that is established by the forward view out of the cockpit and (2) the world centered reference frame that is established by the aircraft's location on a map. The data support a model involving at least two components: (1) the perceptual encoding of the navigational landmarks and (2) the mental rotation of the map's world reference frame into alignment with the ego centered reference frame. The quantitative relationships of these two factors are provided as possible inputs for a computational model of spatial cognition during flight navigation.

  2. Spatial Pinning Control

    NASA Astrophysics Data System (ADS)

    Frasca, Mattia; Buscarino, Arturo; Rizzo, Alessandro; Fortuna, Luigi

    2012-05-01

    In this Letter, we introduce the concept of spatial pinning control for a network of mobile chaotic agents. In a planar space, N agents move as random walkers and interact according to a time-varying r-disk proximity graph. A control input is applied only to those agents which enter a given area, called control region. The control is effective in driving all the agents to a reference evolution and has better performance than pinning control on a fixed set of agents. We derive analytical conditions on the relative size of the control region and the agent density for the global convergence of the system to the reference evolution and study the system under different regimes inherited by the velocity.

  3. Application of the semi-empirical method to determine the spatial distribution function for thermalized photoelectrons created by vacuum ultraviolet or high-energy irradiation of some nonpolar dielectric liquids

    NASA Astrophysics Data System (ADS)

    Guelfucci, J. P.; Fitte-Rey, J.; Casanovas, J.; Baird, J. K.

    1997-06-01

    A semi-empirical method is tested to determine the spatial distribution function of the thermalized photoelectrons, created by vacuum ultraviolet (VUV) or γ irradiations of some liquid alkanes. It seems that modified exponentials must be associated to the thermalization process on VUV irradiation. A Gaussian distribution function could be used for high-energy irradiation. The partial inadequacy of the method in the case of high-energy irradiation can be imputed to the existence of multiple ion pair recombinations.

  4. Testing for spatial association of qualitative data using symbolic dynamics

    NASA Astrophysics Data System (ADS)

    Ruiz, Manuel; López, Fernando; Páez, Antonio

    2010-09-01

    Qualitative spatial variables are important in many fields of research. However, unlike the decades-worth of research devoted to the spatial association of quantitative variables, the exploratory analysis of spatial qualitative variables is relatively less developed. The objective of the present paper is to propose a new test ( Q) for spatial independence. This is a simple, consistent, and powerful statistic for qualitative spatial independence that we develop using concepts from symbolic dynamics and symbolic entropy. The Q test can be used to detect, given a spatial distribution of events, patterns of spatial association of qualitative variables in a wide variety of settings. In order to enable hypothesis testing, we give a standard asymptotic distribution of an affine transformation of the symbolic entropy under the null hypothesis of independence in the spatial qualitative process. We include numerical experiments to demonstrate the finite sample behaviour of the test, and show its application by means of an empirical example that explores the spatial association of fast food establishments in the Greater Toronto Area in Canada.

  5. Solutions for medical databases optimal exploitation

    PubMed Central

    Branescu, I; Purcarea, VL; Dobrescu, R

    2014-01-01

    The paper discusses the methods to apply OLAP techniques for multidimensional databases that leverage the existing, performance-enhancing technique, known as practical pre-aggregation, by making this technique relevant to a much wider range of medical applications, as a logistic support to the data warehousing techniques. The transformations have practically low computational complexity and they may be implemented using standard relational database technology. The paper also describes how to integrate the transformed hierarchies in current OLAP systems, transparently to the user and proposes a flexible, “multimodel" federated system for extending OLAP querying to external object databases. PMID:24653769

  6. Spatial search by quantum walk

    SciTech Connect

    Childs, Andrew M.; Goldstone, Jeffrey

    2004-08-01

    Grover's quantum search algorithm provides a way to speed up combinatorial search, but is not directly applicable to searching a physical database. Nevertheless, Aaronson and Ambainis showed that a database of N items laid out in d spatial dimensions can be searched in time of order {radical}(N) for d>2, and in time of order {radical}(N) poly(log N) for d=2. We consider an alternative search algorithm based on a continuous-time quantum walk on a graph. The case of the complete graph gives the continuous-time search algorithm of Farhi and Gutmann, and other previously known results can be used to show that {radical}(N) speedup can also be achieved on the hypercube. We show that full {radical}(N) speedup can be achieved on a d-dimensional periodic lattice for d>4. In d=4, the quantum walk search algorithm takes time of order {radical}(N) poly(log N), and in d<4, the algorithm does not provide substantial speedup.

  7. Spatial filtering improved tomographic PIV

    NASA Astrophysics Data System (ADS)

    Discetti, Stefano; Natale, Andrea; Astarita, Tommaso

    2013-04-01

    Tomographic reconstruction accuracy is of fundamental importance to obtain reliable three-dimensional three-components velocity field measurements when implementing tomographic particle image velocimetry. Algebraic methods (Herman and Lent 1976) are quite well established to handle the problem in case of high spatial frequency spots on a dark background imaged by a limited number of simultaneous views; however, their efficacy is limited in case of dense distributions to be reconstructed. In the present work, an easy implementable modified version of the commonly used multiplicative algebraic reconstruction technique is proposed, allowing a remarkable improvement of the tomographic reconstruction quality only slightly increasing the computational cost. The technique is based on artificial diffusion applied by Gaussian smoothing after each iteration of the reconstruction procedure. Numerical simulations show that the increase in the reconstruction quality leads to a significant reduction of the modulation effects in the velocity measurement due to the coherent ghost particles motion. An experimental application in fractal grid turbulence highlights an improvement of the signal strength and a reduction of the uncertainty in the velocity measurement.

  8. Non-uniform spatial response of the LCoS spatial light modulator

    NASA Astrophysics Data System (ADS)

    Lopez, Víctor; González-Vega, Arturo; Aguilar, Alberto; Landgrave, J. E. A.; García-Márquez, Jorge

    2016-05-01

    Liquid crystal on silicon (LCoS) spatial light modulators have been considered for a wide variety of scientific applications, due to their phase modulation capability and high spatial resolution. Nevertheless, their intrinsic characteristics, like the extensively studied depolarization and phase shift fluctuations, can make their behavior significantly distant from the ideal and somewhat unpredictable. Here, we present the characterization of a different source of uncertainty: the non-uniform spatial response of the LCoS, which is fundamentally different to the static aberrations of the panel. We measured local deviations of ±22% from the expected phase shift, resulting in non-negligible effects for phase modulation measurements, phase shifting interferometry, wavefront correction, and speckle interferometry.

  9. Chemistry with spatial control using particles and streams†

    PubMed Central

    Kalinin, Yevgeniy V.; Murali, Adithya

    2012-01-01

    Spatial control of chemical reactions, with micro- and nanometer scale resolution, has important consequences for one pot synthesis, engineering complex reactions, developmental biology, cellular biochemistry and emergent behavior. We review synthetic methods to engineer this spatial control using chemical diffusion from spherical particles, shells and polyhedra. We discuss systems that enable both isotropic and anisotropic chemical release from isolated and arrayed particles to create inhomogeneous and spatially patterned chemical fields. In addition to such finite chemical sources, we also discuss spatial control enabled with laminar flow in 2D and 3D microfluidic networks. Throughout the paper, we highlight applications of spatially controlled chemistry in chemical kinetics, reaction-diffusion systems, chemotaxis and morphogenesis. PMID:23145348

  10. Modeling structural change in spatial system dynamics: A Daisyworld example

    PubMed Central

    Neuwirth, C.; Peck, A.; Simonović, S.P.

    2015-01-01

    System dynamics (SD) is an effective approach for helping reveal the temporal behavior of complex systems. Although there have been recent developments in expanding SD to include systems’ spatial dependencies, most applications have been restricted to the simulation of diffusion processes; this is especially true for models on structural change (e.g. LULC modeling). To address this shortcoming, a Python program is proposed to tightly couple SD software to a Geographic Information System (GIS). The approach provides the required capacities for handling bidirectional and synchronized interactions of operations between SD and GIS. In order to illustrate the concept and the techniques proposed for simulating structural changes, a fictitious environment called Daisyworld has been recreated in a spatial system dynamics (SSD) environment. The comparison of spatial and non-spatial simulations emphasizes the importance of considering spatio-temporal feedbacks. Finally, practical applications of structural change models in agriculture and disaster management are proposed. PMID:26109906

  11. Quadratic spatial soliton interactions

    NASA Astrophysics Data System (ADS)

    Jankovic, Ladislav

    Quadratic spatial soliton interactions were investigated in this Dissertation. The first part deals with characterizing the principal features of multi-soliton generation and soliton self-reflection. The second deals with two beam processes leading to soliton interactions and collisions. These subjects were investigated both theoretically and experimentally. The experiments were performed by using potassium niobate (KNBO 3) and periodically poled potassium titanyl phosphate (KTP) crystals. These particular crystals were desirable for these experiments because of their large nonlinear coefficients and, more importantly, because the experiments could be performed under non-critical-phase-matching (NCPM) conditions. The single soliton generation measurements, performed on KNBO3 by launching the fundamental component only, showed a broad angular acceptance bandwidth which was important for the soliton collisions performed later. Furthermore, at high input intensities multi-soliton generation was observed for the first time. The influence on the multi-soliton patterns generated of the input intensity and beam symmetry was investigated. The combined experimental and theoretical efforts indicated that spatial and temporal noise on the input laser beam induced multi-soliton patterns. Another research direction pursued was intensity dependent soliton routing by using of a specially engineered quadratically nonlinear interface within a periodically poled KTP sample. This was the first time demonstration of the self-reflection phenomenon in a system with a quadratic nonlinearity. The feature investigated is believed to have a great potential for soliton routing and manipulation by engineered structures. A detailed investigation was conducted on two soliton interaction and collision processes. Birth of an additional soliton resulting from a two soliton collision was observed and characterized for the special case of a non-planar geometry. A small amount of spiraling, up to 30

  12. ALGORITHM DEVELOPMENT FOR SPATIAL OPERATORS.

    USGS Publications Warehouse

    Claire, Robert W.

    1984-01-01

    An approach is given that develops spatial operators about the basic geometric elements common to spatial data structures. In this fashion, a single set of spatial operators may be accessed by any system that reduces its operands to such basic generic representations. Algorithms based on this premise have been formulated to perform operations such as separation, overlap, and intersection. Moreover, this generic approach is well suited for algorithms that exploit concurrent properties of spatial operators. The results may provide a framework for a geometry engine to support fundamental manipulations within a geographic information system.

  13. Spatial Query for Planetary Data

    NASA Technical Reports Server (NTRS)

    Shams, Khawaja S.; Crockett, Thomas M.; Powell, Mark W.; Joswig, Joseph C.; Fox, Jason M.

    2011-01-01

    Science investigators need to quickly and effectively assess past observations of specific locations on a planetary surface. This innovation involves a location-based search technology that was adapted and applied to planetary science data to support a spatial query capability for mission operations software. High-performance location-based searching requires the use of spatial data structures for database organization. Spatial data structures are designed to organize datasets based on their coordinates in a way that is optimized for location-based retrieval. The particular spatial data structure that was adapted for planetary data search is the R+ tree.

  14. Spatial Aspects of Interspecific Competition

    NASA Technical Reports Server (NTRS)

    Durrett, Rick; Levin, Simon

    1998-01-01

    Using several variants of a stochastic spatial model introduced by Silvertown et al., we investigate the effect of spatial distribution of individuals on the outcome of competition. First, we prove rigorously that if one species has a competitive advantage over each of the others, then eventually it takes over all the sites in the system. Second, we examine tradeoffs between competition and dispersal distance in a two-species system. Third, we consider a cyclic competitive relationship between three types. In this case, a nonspatial treatment leads to densities that follow neutrally stable cycles or even unstable spiral solutions, while a spatial model yields a stationary distribution with an interesting spatial structure.

  15. Auditory Spatial Layout

    NASA Technical Reports Server (NTRS)

    Wightman, Frederic L.; Jenison, Rick

    1995-01-01

    All auditory sensory information is packaged in a pair of acoustical pressure waveforms, one at each ear. While there is obvious structure in these waveforms, that structure (temporal and spectral patterns) bears no simple relationship to the structure of the environmental objects that produced them. The properties of auditory objects and their layout in space must be derived completely from higher level processing of the peripheral input. This chapter begins with a discussion of the peculiarities of acoustical stimuli and how they are received by the human auditory system. A distinction is made between the ambient sound field and the effective stimulus to differentiate the perceptual distinctions among various simple classes of sound sources (ambient field) from the known perceptual consequences of the linear transformations of the sound wave from source to receiver (effective stimulus). Next, the definition of an auditory object is dealt with, specifically the question of how the various components of a sound stream become segregated into distinct auditory objects. The remainder of the chapter focuses on issues related to the spatial layout of auditory objects, both stationary and moving.

  16. One Spatial Map or Many? Spatial Coding of Connected Environments

    ERIC Educational Resources Information Center

    Han, Xue; Becker, Suzanna

    2014-01-01

    We investigated how humans encode large-scale spatial environments using a virtual taxi game. We hypothesized that if 2 connected neighborhoods are explored jointly, people will form a single integrated spatial representation of the town. However, if the neighborhoods are first learned separately and later observed to be connected, people will…

  17. Entangling the spatial properties of laser beams.

    PubMed

    Wagner, Katherine; Janousek, Jiri; Delaubert, Vincent; Zou, Hongxin; Harb, Charles; Treps, Nicolas; Morizur, Jean François; Lam, Ping Koy; Bachor, Hans A

    2008-07-25

    Position and momentum were the first pair of conjugate observables explicitly used to illustrate the intricacy of quantum mechanics. We have extended position and momentum entanglement to bright optical beams. Applications in optical metrology and interferometry require the continuous measurement of laser beams, with the accuracy fundamentally limited by the uncertainty principle. Techniques based on spatial entanglement of the beams could overcome this limit, and high-quality entanglement is required. We report a value of 0.51 for inseparability and 0.62 for the Einstein-Podolsky-Rosen criterion, both normalized to a classical limit of 1. These results are a conclusive optical demonstration of macroscopic position and momentum quantum entanglement and also confirm that the resources for spatial multimode protocols are available. PMID:18653887

  18. The Spatial Infrared Imaging Telescope III.

    NASA Astrophysics Data System (ADS)

    Bartschi, B. Y.; Morse, D. E.; Woolston, T. L.

    1996-06-01

    The Spatial Infrared Imaging Telescope III (SPIRIT III) is a mid- through long-wave infrared instrumentation package built and managed by the Space Dynamics Laboratory at Utah State University for the Midcourse Space Experiment. SPIRIT III contains a radiometer and an auto-aligning interferometer-spectrometer that share a telescope designed for high off-axis rejection. A solid-hydrogen cryostat, the first of its kind to be used in a space/satellite application, cools the entire sensor system to cryogenic operating temperatures. This hardware will measure the spectral, spatial, temporal, and intensity characteristics of Earth-limb backgrounds, celestial objects, and other upper atmospheric phenomena. Collected data will provide answers to fundamental questions about Department of Defense surveillance systems and supply invaluable information for system planners and designers of future threat detection systems.

  19. Recording of brain activity across spatial scales.

    PubMed

    Lewis, C M; Bosman, C A; Fries, P

    2015-06-01

    Brain activity reveals exquisite coordination across spatial scales, from local microcircuits to brain-wide networks. Understanding how the brain represents, transforms and communicates information requires simultaneous recordings from distributed nodes of whole brain networks with single-cell resolution. Realizing multi-site recordings from communicating populations is hampered by the need to isolate clusters of interacting cells, often on a day-to-day basis. Chronic implantation of multi-electrode arrays allows long-term tracking of activity. Lithography on thin films provides a means to produce arrays of variable resolution, a high degree of flexibility, and minimal tissue displacement. Sequential application of surface arrays to monitor activity across brain-wide networks and subsequent implantation of laminar arrays to target specific populations enables continual refinement of spatial scale while maintaining coverage. PMID:25544724

  20. Spatial uncertainty analysis: Propagation of interpolation errors in spatially distributed models

    USGS Publications Warehouse

    Phillips, D.L.; Marks, D.G.

    1996-01-01

    In simulation modelling, it is desirable to quantify model uncertainties and provide not only point estimates for output variables but confidence intervals as well. Spatially distributed physical and ecological process models are becoming widely used, with runs being made over a grid of points that represent the landscape. This requires input values at each grid point, which often have to be interpolated from irregularly scattered measurement sites, e.g., weather stations. Interpolation introduces spatially varying errors which propagate through the model We extended established uncertainty analysis methods to a spatial domain for quantifying spatial patterns of input variable interpolation errors and how they propagate through a model to affect the uncertainty of the model output. We applied this to a model of potential evapotranspiration (PET) as a demonstration. We modelled PET for three time periods in 1990 as a function of temperature, humidity, and wind on a 10-km grid across the U.S. portion of the Columbia River Basin. Temperature, humidity, and wind speed were interpolated using kriging from 700- 1000 supporting data points. Kriging standard deviations (SD) were used to quantify the spatially varying interpolation uncertainties. For each of 5693 grid points, 100 Monte Carlo simulations were done, using the kriged values of temperature, humidity, and wind, plus random error terms determined by the kriging SDs and the correlations of interpolation errors among the three variables. For the spring season example, kriging SDs averaged 2.6??C for temperature, 8.7% for relative humidity, and 0.38 m s-1 for wind. The resultant PET estimates had coefficients of variation (CVs) ranging from 14% to 27% for the 10-km grid cells. Maps of PET means and CVs showed the spatial patterns of PET with a measure of its uncertainty due to interpolation of the input variables. This methodology should be applicable to a variety of spatially distributed models using interpolated

  1. Spatial Database Modeling for Indoor Navigation Systems

    NASA Astrophysics Data System (ADS)

    Gotlib, Dariusz; Gnat, Miłosz

    2013-12-01

    For many years, cartographers are involved in designing GIS and navigation systems. Most GIS applications use the outdoor data. Increasingly, similar applications are used inside buildings. Therefore it is important to find the proper model of indoor spatial database. The development of indoor navigation systems should utilize advanced teleinformation, geoinformatics, geodetic and cartographical knowledge. The authors present the fundamental requirements for the indoor data model for navigation purposes. Presenting some of the solutions adopted in the world they emphasize that navigation applications require specific data to present the navigation routes in the right way. There is presented original solution for indoor data model created by authors on the basis of BISDM model. Its purpose is to expand the opportunities for use in indoor navigation.

  2. Low Voltage Spatial Light Modulator

    SciTech Connect

    Papavasiliou, A

    2003-02-19

    This project studied the feasibility of a Low-Voltage actuator technology that promises to reduce the switched voltage requirements and linearize the response of spatial light modulators. We created computer models that demonstrate substantial advantages offered by this technology, and fabricated and tested those devices. SLMs are electro-optic devices for modulating the phase, amplitude or angle of light beams, laser or other. Applications for arrays of SLMs include turbulence correction for high-speed optical communications, imaging through distorting media, input devices for holographic memories, optical manipulation of DNA molecules, and optical computers. Devices based on micro electro-mechanical systems (MEMS) technology have recently become of special interest because of their potential for greatly improved performance at a much lower cost than piezoelectric or liquid crystal based devices. The new MEMS-based SLM devices could have important applications in high-speed optical communication and remote optical sensing, in support of DoD and DOE missions. Virtually all previously demonstrated MEMS SLMs are based on parallel-plate capacitors where an applied voltage causes a mirror attached to a suspended electrode to move towards a fixed electrode. They require relatively high voltages, typically on the order of 100 V, resulting in (1) large transistor sizes, available only from specialized foundries at significant cost and limiting the amount/sophistication of electronics under each SLM pixel, and (2) large power dissipation/area, resulting in a heat removal issue because of the optical precision required ({approx} 1/50-th of a wavelength). The actuator described in this process uses an advanced geometry that was invented at LLNL and is currently still proprietary. The new geometry allows the application of a bias voltage. This applied bias voltage results in a reduction of the required switched voltage and a linearization of the response curve. When this

  3. Demonstration of polarization-insensitive spatial light modulation using a single polarization-sensitive spatial light modulator

    PubMed Central

    Liu, Jun; Wang, Jian

    2015-01-01

    We present a simple configuration incorporating a single polarization-sensitive phase-only liquid crystal spatial light modulator (LC-SLM) to facilitate polarization-insensitive spatial light modulation. The polarization-insensitive configuration is formed by a polarization beam splitter (PBS), a polarization-sensitive phase-only LC-SLM, a half-wave plate (HWP), and a mirror in a loop structure. We experimentally demonstrate polarization-insensitive spatial light modulations for incident linearly polarized beams with different polarization states and polarization-multiplexed beams. Polarization-insensitive spatial light modulations generating orbital angular momentum (OAM) beams are demonstrated in the experiment. The designed polarization-insensitive configuration may find promising applications in spatial light modulations accommodating diverse incident polarizations. PMID:26146032

  4. Digital phantoms generated by spectral and spatial light modulators

    NASA Astrophysics Data System (ADS)

    Chon, Bonghwan; Tokumasu, Fuyuki; Lee, Ji Youn; Allen, David W.; Rice, Joseph P.; Hwang, Jeeseong

    2015-12-01

    A hyperspectral image projector (HIP) based on liquid crystal on silicon spatial light modulators is explained and demonstrated to generate data cubes. The HIP-constructed data cubes are three-dimensional images of the spatial distribution of spectrally resolved abundances of intracellular light-absorbing oxyhemoglobin molecules in single erythrocytes. Spectrally and spatially resolved image data indistinguishable from the real scene may be used as standard data cubes, so-called digital phantoms, to calibrate image sensors and validate image analysis algorithms for their measurement quality, performance consistency, and interlaboratory comparisons for quantitative biomedical imaging applications.

  5. Digital phantoms generated by spectral and spatial light modulators.

    PubMed

    Chon, Bonghwan; Tokumasu, Fuyuki; Lee, Ji Youn; Allen, David W; Rice, Joseph P; Hwang, Jeeseong

    2015-01-01

    A hyperspectral image projector (HIP) based on liquid crystal on silicon spatial light modulators is explained and demonstrated to generate data cubes. The HIP-constructed data cubes are three-dimensional images of the spatial distribution of spectrally resolved abundances of intracellular light-absorbing oxyhemoglobin molecules in single erythrocytes. Spectrally and spatially resolved image data indistinguishable from the real scene may be used as standard data cubes, so-called digital phantoms, to calibrate image sensors and validate image analysis algorithms for their measurement quality, performance consistency, and interlaboratory comparisons for quantitative biomedical imaging applications. PMID:26361340

  6. Digital phantoms generated by spectral and spatial light modulators.

    PubMed

    Chon, Bonghwan; Tokumasu, Fuyuki; Lee, Ji Youn; Allen, David W; Rice, Joseph P; Hwang, Jeeseong

    2015-12-01

    A hyperspectral image projector (HIP) based on liquid crystal on silicon spatial light modulators is explained and demonstrated to generate data cubes. The HIP-constructed data cubes are three-dimensional images of the spatial distribution of spectrally resolved abundances of intracellular light-absorbing oxyhemoglobin molecules in single erythrocytes. Spectrally and spatially resolved image data indistinguishable from the real scene may be used as standard data cubes, so-called digital phantoms, to calibrate image sensors and validate image analysis algorithms for their measurement quality, performance consistency, and interlaboratory comparisons for quantitative biomedical imaging applications. PMID:26502383

  7. Spatial vulnerability assessments by regression kriging

    NASA Astrophysics Data System (ADS)

    Pásztor, László; Laborczi, Annamária; Takács, Katalin; Szatmári, Gábor

    2016-04-01

    information representing IEW or GRP forming environmental factors were taken into account to support the spatial inference of the locally experienced IEW frequency and measured GRP values respectively. An efficient spatial prediction methodology was applied to construct reliable maps, namely regression kriging (RK) using spatially exhaustive auxiliary data on soil, geology, topography, land use and climate. RK divides the spatial inference into two parts. Firstly the deterministic component of the target variable is determined by a regression model. The residuals of the multiple linear regression analysis represent the spatially varying but dependent stochastic component, which are interpolated by kriging. The final map is the sum of the two component predictions. Application of RK also provides the possibility of inherent accuracy assessment. The resulting maps are characterized by global and local measures of its accuracy. Additionally the method enables interval estimation for spatial extension of the areas of predefined risk categories. All of these outputs provide useful contribution to spatial planning, action planning and decision making. Acknowledgement: Our work was partly supported by the Hungarian National Scientific Research Foundation (OTKA, Grant No. K105167).

  8. Programmable fabrication of spatial structures in a gas jet by laser machining with a spatial light modulator

    SciTech Connect

    Lin, M.-W.; Chen, Y.-M.; Pai, C.-H.; Kuo, C.-C.; Lee, K.-H.; Wang, J.; Chen, S.-Y.; Lin, J.-Y.

    2006-11-15

    Programmable fabrication of longitudinal spatial structures in a gas jet was achieved by using laser machining with a liquid-crystal spatial light modulator as the pattern mask. By this technique single-shot fabrication of arbitrary gas and/or plasma structures is demonstrated, which establishes the crucial step toward raising the designs and applications of high-field plasma devices to the level of adaptive feedback optimization.

  9. Manakov spatial solitons

    NASA Astrophysics Data System (ADS)

    Kang, J. U.; Stegeman, G. I.; Aitchison, J. S.; Akhmediev, N.

    1996-12-01

    The Manakov soliton is a two-component soliton that was first considered by Manakov in the early 1970s.1 Based on the work of Zakharov and Shabat,2 Manakov found that the coupled nonlinear Schrodinger (CNSE) equations with special choice of the coefficients in front of nonlinear terms can be solved exactly. This system is integrable and solitons have therefore a number of special properties which might be useful in practice. In particular, for same total power, the soliton of a single nonlinear Schrodinger equation and the Manakov soliton behave similarly. There are certain conditions for the integrability of the CNSE. Namely, for the coupled set of equations with cubic nonlinearity, the ratio between the self-phase modulation (SPM) to the cross-phase modulation coefficients has to be equal to unity, and the SPM coefficients need to be equal for the two polarizations. Moreover, the energy exchange terms or four-wave mixing (FWM) terms must be zero. Physically, the Manakov soliton is a mutually trapped state of two orthogonally polarized beams where each component of the soliton experiences exactly the same index potential which is proportional to the total intensity of the beam. There are no crystal symmetries that a priori lead to a SPM/XPM ratio of unity. Thus, the Manakov soliton has not been observed experimentally prior to the work we reported.3 Based on our previous work, we found that in AlGaAs, for photon energies just below half the band gap, the conditions for integrability can be satisfied. This led to the first experimental observation of spatial Manakov solitons.

  10. Automated Verification of Spatial Resolution in Remotely Sensed Imagery

    NASA Technical Reports Server (NTRS)

    Davis, Bruce; Ryan, Robert; Holekamp, Kara; Vaughn, Ronald

    2011-01-01

    Image spatial resolution characteristics can vary widely among sources. In the case of aerial-based imaging systems, the image spatial resolution characteristics can even vary between acquisitions. In these systems, aircraft altitude, speed, and sensor look angle all affect image spatial resolution. Image spatial resolution needs to be verified with estimators that include the ground sample distance (GSD), the modulation transfer function (MTF), and the relative edge response (RER), all of which are key components of image quality, along with signal-to-noise ratio (SNR) and dynamic range. Knowledge of spatial resolution parameters is important to determine if features of interest are distinguishable in imagery or associated products, and to develop image restoration algorithms. An automated Spatial Resolution Verification Tool (SRVT) was developed to rapidly determine the spatial resolution characteristics of remotely sensed aerial and satellite imagery. Most current methods for assessing spatial resolution characteristics of imagery rely on pre-deployed engineered targets and are performed only at selected times within preselected scenes. The SRVT addresses these insufficiencies by finding uniform, high-contrast edges from urban scenes and then using these edges to determine standard estimators of spatial resolution, such as the MTF and the RER. The SRVT was developed using the MATLAB programming language and environment. This automated software algorithm assesses every image in an acquired data set, using edges found within each image, and in many cases eliminating the need for dedicated edge targets. The SRVT automatically identifies high-contrast, uniform edges and calculates the MTF and RER of each image, and when possible, within sections of an image, so that the variation of spatial resolution characteristics across the image can be analyzed. The automated algorithm is capable of quickly verifying the spatial resolution quality of all images within a data

  11. Analyzing spatial and temporal (222)Rn trends in Maine.

    PubMed

    Farah, Christopher; Beard, Kate; Hess, C T; Hock, Janet M

    2012-02-01

    Prolonged radon exposure has been linked to lung cancer. Cancer registry data indicates excess risk for age-adjusted lung cancer in Maine. Maine's mean residential radon activity exceeds the EPA maximum contaminant level (MCL). This paper describes the application of spatial autocorrelation methods to retrospective data as a means of analyzing radon activity in Maine. Retrospective air and well water radon activity data, sampled throughout Maine between 1993 and 2008, are standardized and geocoded for analysis. Three spatial autocorrelation algorithms-local Getis-Ord, local Moran, and spatial scan statistic-are used to identify spatial, temporal, and spatiotemporal radon activity clusters and/or outliers. Spatial clusters of high air- and well water-Rn activity are associated with Maine's Lucerne and Sebago granitic formations. Spatial clusters of low air- and well water-Rn activity are associated with Biddeford Granite and the metamorphic bedrock formation Silurian Ordovician Vassalboro. Space-time analysis indicates that most spatial clusters persist over the period of sampling. No significant temporal clusters are identified. Persistent spatial variations in radon may help to better understand and predict radon-related health risks associated with Maine residences. PMID:22217584

  12. Bayesian Integration of Spatial Information

    ERIC Educational Resources Information Center

    Cheng, Ken; Shettleworth, Sara J.; Huttenlocher, Janellen; Rieser, John J.

    2007-01-01

    Spatial judgments and actions are often based on multiple cues. The authors review a multitude of phenomena on the integration of spatial cues in diverse species to consider how nearly optimally animals combine the cues. Under the banner of Bayesian perception, cues are sometimes combined and weighted in a near optimal fashion. In other instances…

  13. The Space in Spatial Language

    ERIC Educational Resources Information Center

    Carlson, Laura A.; Van Deman, Shannon R.

    2004-01-01

    Projective spatial terms such as ''below'' specify the location of one object by indicating its spatial relation with respect to a reference object. These relations are defined via a reference frame that consists of a number of parameters (orientation, direction, origin, and distance) whose settings configure the space surrounding the reference…

  14. Mechanisms for Human Spatial Competence

    NASA Astrophysics Data System (ADS)

    Gunzelmann, Glenn; Lyon, Don R.

    Research spanning decades has generated a long list of phenomena associated with human spatial information processing. Additionally, a number of theories have been proposed about the representation, organization and processing of spatial information by humans. This paper presents a broad account of human spatial competence, integrated with the ACT-R cognitive architecture. Using a cognitive architecture grounds the research in a validated theory of human cognition, enhancing the plausibility of the overall account. This work posits a close link of aspects of spatial information processing to vision and motor planning, and integrates theoretical perspectives that have been proposed over the history of research in this area. In addition, the account is supported by evidence from neuropsychological investigations of human spatial ability. The mechanisms provide a means of accounting for a broad range of phenomena described in the experimental literature.

  15. Marine spatial planning in practice

    NASA Astrophysics Data System (ADS)

    Collie, Jeremy S.; (Vic) Adamowicz, W. L.; Beck, Michael W.; Craig, Bethany; Essington, Timothy E.; Fluharty, David; Rice, Jake; Sanchirico, James N.

    2013-01-01

    Multiple competing uses of continental-shelf environments have led to a proliferation of marine spatial planning initiatives, together with expert guidance on marine spatial planning. This study provides an empirical review of marine spatial plans, their attributes, and the extent to which the expert guidance is actually being followed. We performed a structured review of 16 existing marine spatial plans and created an idealized marine spatial plan from the steps included in recent expert papers. A cluster analysis of the yes/no answers to 28 questions was used to ordinate the 16 marine spatial plans and to compare them with the idealized plan. All the plans that have been implemented have a high-level government mandate and the authority to implement spatial planning vested in existing institutions. Almost all the plans used data with clear criteria for data inclusion. Stakeholders were included in almost all the plans; they did not participate in all stages of the planning process but their roles were generally clearly defined. Decision-support tools were applied inconsistently across plans and were seldom used dynamically over time. Most spatial planning processes did not select specific outcomes, such as preferred use scenarios. Success is defined inconsistently across plans; in half the cases there are no metrics of success with reference benchmarks. Although monitoring is included in the majority of plans, only in some cases do monitoring results feed back into management decisions. The process of marine spatial planning had advanced in that some of the more recent plans were developed more quickly and contain more desirable attributes than earlier plans. Even so, existing marine spatial plans are heterogeneous—there are essential ingredients, but no single recipe for success.

  16. Six Myths About Spatial Thinking

    NASA Astrophysics Data System (ADS)

    Newcombe, Nora S.; Stieff, Mike

    2012-04-01

    Visualizations are an increasingly important part of scientific education and discovery. However, users often do not gain knowledge from them in a complete or efficient way. This article aims to direct research on visualizations in science education in productive directions by reviewing the evidence for widespread assumptions that learning styles, sex differences, developmental stages, and spatial language determine the impact of visualizations on science learning. First, we examine the assumption that people differ in their verbal versus visual learning style. Due to the lack of rigorous evaluation, there is no current support for this distinction. Future research should distinguish between two different kinds of visual learning style. Second, we consider the belief that there are large and intractable sex differences in spatial ability resultant from immutable biological reasons. Although there are some spatial sex differences (in some types of spatial tests although not all), there is actually only very mixed support for biological causation. Most important, there is conclusive evidence that spatial skills can be improved through training and education. Third, we explore educators' use of Piaget's ideas about spatial development to draw conclusions about 'developmental appropriateness'. However, recent research on spatial development has focused on identifying sequences that begin with early starting points of skill, and spatial education is possible in some form at all ages. Fourth, although spatial language does not determine spatial thought, it does frame attention in a way that can have impact on learning and understanding. We examine the empirical support for each assumption and its relevance to future research on visualizations in science education.

  17. Black Sea spectral bio-optical models based on satellite data and their applications for assessment of spatial and temporal variability in waters transparency, chlorophyll a content and primary production

    NASA Astrophysics Data System (ADS)

    Churilova, T.; Suslin, V.

    2012-04-01

    Satellite observations of ocean color provide a unique opportunity in oceanography to assess productivity of the sea on different spatial and temporal scales. However it has been shown that the standard SeaWiFS algorithm generally overestimates summer chlorophyll concentration and underestimates pigment content during spring phytoplankton bloom in comparison with in situ measurements. It is required to develop regional algorithms which are based on biooptical characteristics typical for the Sea and consequently could be used for correct transformation of spectral features of water-leaving radiance to chlorophyll a concentrations (Chl), light absorption features of suspended and dissolved organic matter (CDM), downwelling light attenuation coefficient/euphotic zone depth (PAR1%) and rate of primary synthesis of organic substances (PP). The numerous measurements of light absorption spectra of phytoplankton, non-algal particles and coloured dissolved organic matter carried out since 1996 in different seasons and regions of the Black Sea allowed to make a parameterization of the light absorption by all optically active components. Taking into account regional peculiarities of the biooptical parameters, their difference between seasons, shallow and deep-waters, their depth-dependent variability within photosynthetic zone regional spectral models for estimation of chlorophyll a concentration (Chl Model), colored dissolved and suspended organic matter absorption (CDM Model), downwelling irradiance (PAR Model) and primary production (PP Model) have been developed based on satellite data. Test of validation of models showed appropriate accuracy of the models. The developed models have been applied for estimation of spatial/temporal variability of chlorophyll a, dissolved organic matter concentrations, waters transparency, euphotic zone depth and primary production based on SeaWiFS data. Two weeks averaged maps of spatial distribution of these parameters have been composed

  18. 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